Single-layer nano-carbon film, diamond film, and diamond/nano-carbon composite film field emission performance comparison

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Xiaoping, E-mail: wxpchina64@aliyun.com, E-mail: wxpchina@sohu.com; Shanghai Key Laboratory of Modern Optical System, Shanghai 200093; Wang, Jinye

A series of single-layer nano-carbon (SNC) films, diamond films, and diamond/nano-carbon (D/NC) composite films have been prepared on the highly doped silicon substrate by using microwave plasma chemical vapor deposition techniques. The films were characterised by scanning electron microscopy, Raman spectroscopy, and field emission I-V measurements. The experimental results indicated that the field emission maximum current density of D/NC composite films is 11.8–17.8 times that of diamond films. And the field emission current density of D/NC composite films is 2.9–5 times that of SNC films at an electric field of 3.0 V/μm. At the same time, the D/NC composite film exhibitsmore » the advantage of improved reproducibility and long term stability (both of the nano-carbon film within the D/NC composite cathode and the SNC cathode were prepared under the same experimental conditions). And for the D/NC composite sample, a high current density of 10 mA/cm{sup 2} at an electric field of 3.0 V/μm was obtained. Diamond layer can effectively improve the field emission characteristics of nano-carbon film. The reason may be due to the diamond film acts as the electron acceleration layer.« less

Electrical Conductance Tuning and Bistable Switching in Poly(N-vinylcarbazole)-Carbon Nanotube Composite Films.

PubMed

Liu, Gang; Ling, Qi-Dan; Teo, Eric Yeow Hwee; Zhu, Chun-Xiang; Chan, D Siu-Hung; Neoh, Koon-Gee; Kang, En-Tang

2009-07-28

By varying the carbon nanotube (CNT) content in poly(N-vinylcarbazole) (PVK) composite thin films, the electrical conductance behavior of an indium-tin oxide/PVK-CNT/aluminum (ITO/PVK-CNT/Al) sandwich structure can be tuned in a controlled manner. Distinctly different electrical conductance behaviors, such as (i) insulator behavior, (ii) bistable electrical conductance switching effects (write-once read-many-times (WORM) memory effect and rewritable memory effect), and (iii) conductor behavior, are discernible from the current density-voltage characteristics of the composite films. The turn-on voltage of the two bistable conductance switching devices decreases and the ON/OFF state current ratio of the WORM device increases with the increase in CNT content of the composite film. Both the WORM and rewritable devices are stable under a constant voltage stress or a continuous pulse voltage stress, with an ON/OFF state current ratio in excess of 10(3). The conductance switching effects of the composite films have been attributed to electron trapping in the CNTs of the electron-donating/hole-transporting PVK matrix.

Piezoelectric response and electrical properties of Pb(Zr1-xTix)O3 thin films: The role of imprint and composition

NASA Astrophysics Data System (ADS)

Cornelius, T. W.; Mocuta, C.; Escoubas, S.; Merabet, A.; Texier, M.; Lima, E. C.; Araujo, E. B.; Kholkin, A. L.; Thomas, O.

2017-10-01

The compositional dependence of the piezoelectric properties of self-polarized PbZr1-xTixO3 (PZT) thin films deposited on Pt/TiO2/SiO2/Si substrates (x = 0.47, 0.49 and 0.50) was investigated by in situ synchrotron X-ray diffraction and electrical measurements. The latter evidenced an imprint effect in the studied PZT films, which is pronounced for films with the composition of x = 0.50 and tends to disappear for x = 0.47. These findings were confirmed by in situ X-ray diffraction along the crystalline [100] and [110] directions of the films with different compositions revealing asymmetric butterfly loops of the piezoelectric strain as a function of the electric field; the asymmetry is more pronounced for the PZT film with a composition of x = 0.50, thus indicating a higher built-in electric field. The enhancement of the dielectric permittivity and the effective piezoelectric coefficient at compositions around the morphotropic phase boundary were interpreted in terms of the polarization rotation mechanism and the monoclinic phase in the studied PZT thin films.

The Effect of Film Composition on the Texture and Grain Size of CuInS2 Prepared by Spray Pyrolysis

NASA Technical Reports Server (NTRS)

Jin, Michael H.; Banger, Kulinder K.; Harris, Jerry D.; Hepp, Aloysius F.

2003-01-01

Ternary single-source precursors were used to deposit CuInS2 thin films using chemical spray pyrolysis. We investigated the effect of the film composition on texture, secondary phase formation, and grain size. As-grown films were most often In-rich. They became more (204/220)-oriented as indium concentration increased, and always contained a yet unidentified secondary phase. The (112)-prefened orientation became more pronounced as the film composition became more Cu-rich. The secondary phase was determined to be an In-rich compound based on composition analysis and Raman spectroscopy. In addition, as-grown Cu-rich (112)-oriented films did not exhibit the In-rich compound. Depositing a thin Cu layer prior to the growth of CuInS2 increased the maximum grain size from - 0.5 micron to - 1 micron, and prevented the formation of the In-rich secondary phase.

Microcontact printing for patterning carbon nanotube/polymer composite films with electrical conductivity.

PubMed

Ogihara, Hitoshi; Kibayashi, Hiro; Saji, Tetsuo

2012-09-26

Patterned carbon nanotube (CNT)/acrylic resin composite films were prepared using microcontact printing (μCP). To prepare ink for μCP, CNTs were dispersed into propylene glycol monomethyl ether acetate (PGMEA) solution in which acrylic resin and a commercially available dispersant (Disperbyk-2001) dissolved. The resulting ink were spin-coated onto poly(dimethylsiloxane) (PDMS) stamps. By drying solvent components from the ink, CNT/polymer composite films were prepared over PDMS stamps. Contact between the stamps and glass substrates provided CNT/polymer composite patternings on the substrates. The transfer behavior of the CNT/polymer composite films depended on the thermal-treatment temperature during μCP; thermal treatment at temperatures near the glass-transition temperature (T(g)) of the acrylic resin was effective to form uniform patternings on substrates. Moreover, contact area between polymer and substrates also affect the transfer behavior. The CNT/polymer composite films showed high electrical conductivity, despite the nonconductivity of polymer components, because CNTs in the films were interconnected. The electrical conductivity of the composite films increased as CNT content in the film became higher; as a result, the composite patternings showed almost as high electrical conductivity as previously reported CNT/polymer bulk composites.

Photocatalytic properties of P25-doped TiO2 composite film synthesized via sol-gel method on cement substrate.

PubMed

Guo, Xiang; Rao, Lei; Wang, Peifang; Wang, Chao; Ao, Yanhui; Jiang, Tao; Wang, Wanzhong

2018-04-01

TiO 2 films have received increasing attention for the removal of organic pollutants via photocatalysis. To develop a simple and effective method for improving the photodegradation efficiency of pollutants in surface water, we herein examined the preparation of a P25-TiO 2 composite film on a cement substrate via a sol-gel method. In this case, Rhodamine B (RhB) was employed as the target organic pollutant. The self-generated TiO 2 film and the P25-TiO 2 composite film were characterized by X-ray diffraction (XRD), N 2 adsorption/desorption measurements, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and diffuse reflectance spectroscopy (DRS). The photodegradation efficiencies of the two films were studied by RhB removal in water under UV (ultraviolet) irradiation. Over 4day exposure, the P25-TiO 2 composite film exhibited higher photocatalytic performance than the self-generated TiO 2 film. The photodegradation rate indicated that the efficiency of the P25-TiO 2 composite film was enhanced by the addition of the rutile phase Degussa P25 powder. As such, cooperation between the anatase TiO 2 and rutile P25 nanoparticles was beneficial for separation of the photo-induced electrons and holes. In addition, the influence of P25 doping on the P25-TiO 2 composite films was evaluated. We found that up to a certain saturation point, increased doping enhanced the photodegradation ability of the composite film. Thus, we herein demonstrated that the doping of P25 powders is a simple but effective strategy to prepare a P25-TiO 2 composite film on a cement substrate, and the resulting film exhibits excellent removal efficiency in the degradation of organic pollutants. Copyright © 2017. Published by Elsevier B.V.

Composite films from pectin and fish skin gelatin or soybean flour protein.

PubMed

Liu, LinShu; Liu, Cheng-Kung; Fishman, Marshall L; Hicks, Kevin B

2007-03-21

Composite films were prepared from pectin and fish skin gelatin (FSG) or pectin and soybean flour protein (SFP). The inclusion of protein promoted molecular interactions, resulting in a well-organized homogeneous structure, as revealed by scanning electron microscopy and fracture-acoustic emission analysis. The resultant composite films showed an increase in stiffness and strength and a decrease in water solubility and water vapor transmission rate, in comparison with films cast from pectin alone. The composite films inherited the elastic nature of proteins, thus being more flexible than the pure pectin films. Treating the composite films with glutaraldehyde/methanol induced chemical cross-linking with the proteins and reduced the interstitial spaces among the macromolecules and, consequently, improved their mechanical properties and water resistance. Treating the protein-free pectin films with glutaraldehyde/methanol also improved the Young's modulus and tensile strength, but showed little effect on the water resistance, because the treatment caused only dehydration of the pectin films and the dehydration is reversible. The composite films were biodegradable and possessed moderate mechanical properties and a low water vapor transmission rate. Therefore, the films are considered to have potential applications as packaging or coating materials for food or drug industries.

Preparation of hybrid nano biocomposite κ-carrageenan/cellulose nanocrystal/nanoclay

NASA Astrophysics Data System (ADS)

Zakuwan, Siti Zarina; Ahmad, Ishak; Ramli, Nazaruddin

2013-11-01

Biodegradable composites film based on κ-carrageenan and nano particles as filler was prepared to study the mechanical strength of carrageenan composites. Solution casting technique was used to prepare_this biocomposite. Preparation of composite film and nano filler involve two stages, preparation of cellulose nanocrystals (CNC) from kenaf with alkali treatment, bleaching, and hydrolysis followed by the preparation of two types of nano composite. Tensile test was carried on the composite film based on κ-carrageenan with the variation percentage of CNC and nano clay to obtain the optimum CNC and nano clay loading. After that hybrid nano-biocomposite film based on κ-carrageenan with the variation percentage of CNC/nano clay (OMMT) according to optimum value of composite carrageenan/CNC and composite carrageenan/nano clay film was prepared. The effect of nano filler on the mechanical properties of carrageenan films was examined. κ-carrageenan biocomposite increased with the optimum at 4% CNC and nano clay composition. Additional improvement of tensile strength with hybridization of CNC and nanoclay indicated better mechanical properties.

Thin Semiconductor/Metal Films For Infrared Devices

NASA Technical Reports Server (NTRS)

Lamb, James L.; Nagendra, Channamallappa L.

1995-01-01

Spectral responses of absorbers and reflectors tailored. Thin cermet films composites of metals and semiconductors undergoing development for use as broadband infrared reflectors and absorbers. Development extends concepts of semiconductor and dielectric films used as interference filters for infrared light and visible light. Composite films offer advantages over semiconductor films. Addition of metal particles contributes additional thermal conductivity, reducing thermal gradients and associated thermal stresses, with resultant enhancements of thermal stability. Because values of n in composite films made large, same optical effects achieved with lesser thicknesses. By decreasing thicknesses of films, one not only decreases weights but also contributes further to reductions of thermal stresses.

Moisture Absorption Behaviour of Biopolymer Polycapralactone (PCL) / Organo Modified Montmorillonite Clay (OMMT) biocomposite films

NASA Astrophysics Data System (ADS)

Malik, Neetu; Shrivastava, Sharad; Bandhu Ghosh, Subrata

2018-04-01

Bio composite materials were fabricated using mixing biodegradable polymer polycaptalactone (PCL) and Organo Modified Montmorillonite Clay (OMMT) through solution casting. Various samples of bio composite films were prepared by varying the OMMT wt% composition by 0.1%, 0.5%, 1% and 1.5%. Thereafter, the density and water absorption of the composites were investigated with respect to immersion time in water. The moisture absorption results show that with an increase in weight percentage (from 0.1 to wt 1.5%) of OMMT within the bio polymer films, the absorption value of bio-nanocomposite films reduced rapidly from 34.4% to 22.3%. The density of hybrid composites also increased with increase in weight percentage of OMMT. The swelling characteristic of PCL increased with increasing % of OMMT clay. These results indicate that the optimized composition of constituents in composite membrane could effectively reduce the anhydrous conditions of bio-composite film.

Composition variations in pulsed-laser-deposited Y-Ba-Cu-O thin films as a function of deposition parameters

NASA Technical Reports Server (NTRS)

Foote, M. C.; Jones, B. B.; Hunt, B. D.; Barner, J. B.; Vasquez, R. P.; Bajuk, L. J.

1992-01-01

The composition of pulsed-ultraviolet-laser-deposited Y-Ba-Cu-O films was examined as a function of position across the substrate, laser fluence, laser spot size, substrate temperature, target conditioning, oxygen pressure and target-substrate distance. Laser fluence, laser spot size, and substrate temperature were found to have little effect on composition within the range investigated. Ablation from a fresh target surface results in films enriched in copper and barium, both of which decrease in concentration until a steady state condition is achieved. Oxygen pressure and target-substrate distance have a significant effect on film composition. In vacuum, copper and barium are slightly concentrated at the center of deposition. With the introduction of an oxygen background pressure, scattering results in copper and barium depletion in the deposition center, an effect which increases with increasing target-substrate distance. A balancing of these two effects results in stoichiometric deposition.

Fabrication and characterization of compositionally-graded shape memory alloy films

NASA Astrophysics Data System (ADS)

Cole, Daniel Paul

2009-12-01

The miniaturization of engineering devices has created interest in new actuation methods capable of high power and high frequency responses. Shape memory alloy (SMA) thin films have exhibited one of the highest power densities of any material used in these actuation schemes. However, they currently require complex thermomechanical training in order to be actuated, which becomes more difficult as devices approach the microscale. Previous studies have indicated that SMA films with compositional gradients have the added feature of an intrinsic two-way shape memory effect (SME). In this work, a new method for processing and characterizing compositionally-graded transformable thin films is presented. Graded NiTi SMA films were processed using magnetron sputtering. Single and multilayer graded films were deposited onto bulk NiTi substrates and single crystal silicon substrates, respectively. Annealing the films naturally produced a compositional gradient across the film-substrate or film-film interface through diffusion modification. The films were directly characterized using a combination of atomic force microscopy (AFM), x-ray diffraction and Auger electron spectroscopy. The compositional gradient was indirectly characterized by measuring the variation in mechanical properties as a function of depth using nanoindentation. The similarity of the indentation response on graded films of varying thickness was used to estimate the width of the graded interface. The nanoindentation response was predicted using an analysis that accounted for the transformation effects occurring under the tip during loading and the variation of elastic modulus resulting from the compositional gradient. The recovery mechanisms of the graded films are compared with homogeneous films using a new nanoscale technique. An AFM integrated with a heating and cooling stage was used to observe the recovery of inelastic deformation caused through nanoindentation. The graded films exhibited a two-way SME with a reduced hysteresis, while the homogeneous films exhibited the classical one-way SME. The fabrication and characterization techniques developed in this work have the potential to be applied to general graded and multi-layer film systems.

Cosputtering crystal growth of zinc oxide-based composite films: From the effects of doping to phase on photoactivity and gas sensing properties

NASA Astrophysics Data System (ADS)

Liang, Yuan-Chang; Lee, Chia-Min

2016-10-01

ZnO-In2O3 (InO) composite thin films were grown by radio frequency cosputtering ZnO and InO ceramic targets in this study. The indium content of the composite films was varied from 1.7 at. % to 8.2 at. % by varying the InO sputtering power during cosputtering thin-film growth. X-ray diffraction and transmission electron microscopy analysis results show that the high indium content leads to the formation of a separated InO phase in the ZnO matrix. The surface crystallite size and roughness of the ZnO-InO composite films grown here increased with an increasing indium content. Furthermore, under the conditions of a higher indium content and InO sputtering power, the number of crystal defects in the composite films increased, and the optical absorbance edge of the composite films broadened. The photoactivity and ethanol gas sensing response of the ZnO-InO composite films increased as their indium content increased; this finding is highly correlated with the microstructural evolution of ZnO-InO composite films of various indium contents, which is achieved by varying the InO sputtering power during cosputtering.

Synthesis and characterization of Au-MWCNT/PEDOT: PSS composite film for optoelectronic applications

NASA Astrophysics Data System (ADS)

Jasna, M.; Anjana, R.; Jayaraj, M. K.

2017-08-01

Recently, flexible organic optoelectronics have got great attention because of their light weight, mechanical flexibility and cost effective fabrication process. Conjugated polymers like PEDOT: PSS are widely used for the transparent electrode applications due to its chemical stability, high conductivity, flexibility and optical transparency in the visible region. Conductivity of the PEDOT: PSS polymer can be enhanced by adding organic solvents or conducting nano fillers like CNT, graphene, etc. Carbon nanotubes are good nano fillers to enhance the conductivity and mechanical strength of PEDOT: PSS composite film. Inthe present work, the effect of gold nano particles in PEDOT: PSS/CNT composite is studied. The conductivity enhancement in PEDOT: PSS/CNT thin films can be attributed to the formation of CNT network in the polymer matrix and conformational change of the PEDOT from benzoid to quinoid structure. Even though the conductivity was enhanced, the transparency of the composite thin films decreased with increase in CNT concentration. To overcome this problem, gold nano particles were attached to CNT walls via chemical route. AuMWCNT/PEDOT: PSS composite films were prepared by spin coating method. TEM images confirmed the decoration of gold nano particles on CNT walls. Electrical and optical properties of the composite films were studied. This simple solution processed conducting films are suitable for optoelectronic applications

Effects of antibacterial nanostructured composite films on vascular stents: hemodynamic behaviors, microstructural characteristics, and biomechanical properties.

PubMed

Cheng, Han-Yi; Hsiao, Wen-Tien; Lin, Li-Hsiang; Hsu, Ya-Ju; Sinrang, Andi Wardihan; Ou, Keng-Liang

2015-01-01

The purpose of this research was to investigate stresses resulting from different thicknesses and compositions of hydrogenated Cu-incorporated diamond-like carbon (a-C:H/Cu) films at the interface between vascular stent and the artery using three-dimensional reversed finite element models (FEMs). Blood flow velocity variation in vessels with plaques was examined by angiography, and the a-C:H/Cu films were characterized by transmission electron microscopy to analyze surface morphology. FEMs were constructed using a computer-aided reverse design system, and the effects of antibacterial nanostructured composite films in the stress field were investigated. The maximum stress in the vascular stent occurred at the intersections of net-like structures. Data analysis indicated that the stress decreased by 15% in vascular stents with antibacterial nanostructured composite films compared to the control group, and the stress decreased with increasing film thickness. The present results confirmed that antibacterial nanostructured composite films improve the biomechanical properties of vascular stents and release abnormal stress to prevent restenosis. The results of the present study offer the clinical benefit of inducing superior biomechanical behavior in vascular stents. © 2014 Wiley Periodicals, Inc.

The Effect of the Melt Viscosity and Impregnation of a Film on the Mechanical Properties of Thermoplastic Composites

PubMed Central

Kim, Jong Won; Lee, Joon Seok

2016-01-01

Generally, to produce film-type thermoplastic composites with good mechanical properties, high-performance reinforcement films are used. In this case, films used as a matrix are difficult to impregnate into tow due to their high melt viscosity and high molecular weight. To solve the problem, in this paper, three polypropylene (PP) films with different melt viscosities were used separately to produce film-type thermoplastic composites. A film with a low melt viscosity was stacked so that tow was impregnated first and a film with a higher melt viscosity was then stacked to produce the composite. Four different composites were produced by regulating the pressure rising time. The thickness, density, fiber volume fraction (Vf), and void content (Vc) were analyzed to identify the physical properties and compare them in terms of film stacking types. The thermal properties were identified by using differential scanning calorimetry (DSC) and dynamical mechanical thermal analysis (DMTA). The tensile property, flexural property, interlaminar shear strength (ILSS), and scanning electron microscopy (SEM) were performed to identify the mechanical properties. For the films with low molecular weight, impregnation could be completed fast but showed low strength. Additionally, the films with high molecular weight completed impregnation slowly but showed high strength. Therefore, appropriate films should be used considering the forming process time and their mechanical properties to produce film-type composites. PMID:28773572

Effect of cocoa pod husk filler loading on tensile properties of cocoa pod husk/polylactic acid green biocomposite films

NASA Astrophysics Data System (ADS)

Sanyang, M. L.; Sapuan, S. M.; Haron, M.

2017-10-01

Over the years, cocoa-pod husk (CPH) generation significantly increased due to the growing global demand of chocolate products, since cocoa bean is the main ingredient for chocolate production. Proper utilization of CPH as natural filler for reinforcement of polymer composites provides economic advantages as well as environmental solutions for CPH waste disposal problems. In this study, CPH filled PLA composite films were developed using solution casting method. The effect of CPH loading on the tensile properties of CPH/PLA composite films were investigated. The obtained results manifested that increasing CPH loading from 0% to 10 % significantly increased tensile strength of CPH/PLA composite. However, further addition of CPH loading up to 15 % decreased the tensile strength of film samples. As CPH loading increased from 0% to 15%, tensile modulus of CPH/PLA composite films also increased from 1.5MPa to 10.4MPa, whereas their elongation at break reduced from 190% to 90%. These findings points out CPH as a potential natural filler for reinforcing thermoplastic polymer composites.

Compositional and moisture content effects on the biodegradability of zein/ethylcellulose films.

PubMed

Romero-Bastida, Claudia A; Flores-Huicochea, Eduardo; Martin-Polo, Martha O; Velazquez, Gonzalo; Torres, J Antonio

2004-04-21

The effect of moisture content and film composition on biodegradability is the focus of this study. Flexible films were first characterized for the effect on water sorption isotherms of relative humidity, temperature, zein content, and the addition of the plasticizers stearic acid, poly(ethylene glycol), or etoxylated ricine oil. Zein/ethylcellulose (EC) mixture films had a behavior between that for pure zein and EC films, which had the lowest water sorption. For films with plasticizer, the lowest water sorption at 25 degrees C was observed for those with stearic acid. Biodegradability of zein/EC films, evaluated using bacterial cultures selected for their zein proteolytic activity and isolated from a local solid waste landfill and a lagoon, showed no plasticizer effect even though its effect on moisture content was significant. Large differences were observed at different film zein concentration with the highest biodegradability for 100% zein. However, biodegradability did not mimic the water sorption behavior of zein/EC mixture films.

Effect of composition on SILAR deposited CdxZn1-xS thin films

NASA Astrophysics Data System (ADS)

Ashith V., K.; Gowrish Rao, K.

2018-04-01

In the group of II-VI compound semiconductor, cadmium zinc sulphide (CdxZn1-xS) thin films have broad application in photovoltaic, optoelectronic devices etc. For heterojunction aspects, CdxZn1-xS thin film can be used as heterojunction partner for CdTe as the absorber layer. In this work, CdZnS thin films prepared on glass substrates by Successive Ion Layer Adsorption and Reaction (SILAR) method by varying the composition. The XRD patterns of deposited films showed polycrystalline with the hexagonal phase. The crystallite size of the films was estimated from W-H plot. The bond length of the film varied w.r.to the composition of the CdxZn1-xS films. The urbach energy of the films was calcualted from absorbance data.

Hybrid Composites for LH2 Fuel Tank Structure

NASA Technical Reports Server (NTRS)

Grimsley, Brian W.; Cano, Roberto J.; Johnston, Norman J.; Loos, Alfred C.; McMahon, William M.

2001-01-01

The application of lightweight carbon fiber reinforced plastics (CFRP) as structure for cryogenic fuel tanks is critical to the success of the next generation of Reusable Launch Vehicles (RLV). The recent failure of the X-33 composite fuel tank occurred in part due to microcracking of the polymer matrix, which allowed cryogen to permeate through the inner skin to the honeycomb core. As part of an approach to solve these problems, NASA Langley Research Center (LaRC) and Marshall Space Flight Center (MSFC) are working to develop and investigate polymer films that will act as a barrier to the permeation of LH2 through the composite laminate. In this study two commercially available films and eleven novel LaRC films were tested in an existing cryogenics laboratory at MSFC to determine the permeance of argon at room temperature. Several of these films were introduced as a layer in the composite to form an interleaved, or hybrid, composite to determine the effects on permeability. In addition, the effects of the interleaved layer thickness, number, and location on the mechanical properties of the composite laminate were investigated. In this initial screening process, several of the films were found to exhibit lower permeability to argon than the composite panels tested.

Improved thermal stability of polylactic acid (PLA) composite film via PLA-β-cyclodextrin-inclusion complex systems.

PubMed

Byun, Youngjae; Rodriguez, Katia; Han, Jung H; Kim, Young Teck

2015-11-01

The effects of the incorporation of PLA-β-cyclodextrin-inclusion complex (IC) and β-cyclodextrin (β-CD) on biopolyester PLA films were investigated. Thermal stability, surface morphology, barrier, and mechanical properties of the films were measured at varying IC (1, 3, 5, and 7%) and β-CD (1 and 5%) concentrations. The PLA-IC-composite films (IC-PLA-CFs) showed uniform morphological structure, while samples containing β-CD (β-CD-PLA-CFs) showed high agglomeration of β-CD due to poor interfacial interaction between β-CD and PLA moieties. According to the thermal property analysis, the 5% IC-PLA-CFs showed 6.6 times lower dimensional changes (6.5%) at the temperature range of 20-80°C than that of pure PLA film (43.0%). The increase of IC or β-CD content in the PLA-composite films shifted the glass transition and crystallization temperature to higher temperature regions. The crystallinity of both composite films improved by increasing IC or β-CD content. Both composite films had higher oxygen and water vapor permeability as IC or β-CD content increased in comparison to pure PLA film. All the composite films had less flexibility and lower tensile strength than the pure PLA film. In conclusion, this study shows that the IC technique is valuable to improve the thermal expansion stability of PLA-based films. Published by Elsevier B.V.

Decrease and enhancement of third-order optical nonlinearity in metal-dielectric composite films

NASA Astrophysics Data System (ADS)

Ning, Tingyin; Lu, Heng; Zhou, Yueliang; Man, Baoyuan

2018-04-01

We investigate third-order optical nonlinearity in gold nanoparticles embedded in CaCu3Ti4O12 (CCTO) films using the Z-scan method. We observe that the effective third-order nonlinear optical susceptibilities in such composite films can not only be enhanced, in line with the conventional behavior, but also be decreased, depending on the volume concentration of gold. In particular, the nonlinear absorption behavior can be changed from saturable absorption in pure CCTO films to reversed saturable absorption in composite films, and theoretically, even zero nonlinear absorption could be obtained. These results indicate that it should be possible to tune the third-order optical nonlinearity in Au:CCTO composite films by altering the gold concentration, thus making them suitable for applications in photonic devices.

Graphene Oxide-Polymer Composite Langmuir Films Constructed by Interfacial Thiol-Ene Photopolymerization

NASA Astrophysics Data System (ADS)

Luo, Xiaona; Ma, Kai; Jiao, Tifeng; Xing, Ruirui; Zhang, Lexin; Zhou, Jingxin; Li, Bingbing

2017-02-01

The effective synthesis and self-assembly of graphene oxide (GO) nanocomposites are of key importance for a broad range of nanomaterial applications. In this work, a one-step chemical strategy is presented to synthesize stable GO-polymer Langmuir composite films by interfacial thiol-ene photopolymerization at room temperature, without use of any crosslinking agents and stabilizing agents. It is discovered that photopolymerization reaction between thiol groups modified GO sheets and ene in polymer molecules is critically responsible for the formation of the composite Langmuir films. The film formed by Langmuir assembly of such GO-polymer composite films shows potential to improve the mechanical and chemical properties and promotes the design of various GO-based nanocomposites. Thus, the GO-polymer composite Langmuir films synthesized by interfacial thiol-ene photopolymerization with such a straightforward and clean manner, provide new alternatives for developing chemically modified GO-based hybrid self-assembled films and nanomaterials towards a range of soft matter and graphene applications.

Development and characterisation of composite films made of kefiran and starch.

PubMed

Motedayen, Ali Akbar; Khodaiyan, Faramarz; Salehi, Esmail Atai

2013-02-15

In this study, new edible composite films were prepared by blending kefiran with corn starch. Film-forming solutions of different ratios of kefiran to corn starch (100/0, 70/30, 50/50, 30/70) were cast at room temperature. The effects of starch addition on the resulting films' physical, mechanical and water-vapor permeability (WVP) properties were investigated. Increasing starch content from 0% to 50% (v/v) decreased the WVP of films; however, with further starch addition the WVP increased. Also, this increase in starch content increased the tensile strength and extensibility of the composite films. However, these mechanical properties decreased at higher starch contents. Dynamic mechanical thermal analysis (DMTA) curves showed that addition of starch at all levels increased the glass transition temperature of films. The electron scanning micrograph for the composite film was homogeneous, without signs of phase separation between the components. Thus, it was observed that these two film-forming components were compatible, and that an interaction existed between them. Copyright © 2012 Elsevier Ltd. All rights reserved.

TiN films fabricated by reactive gas pulse sputtering: A hybrid design of multilayered and compositionally graded structures

NASA Astrophysics Data System (ADS)

Yang, Jijun; Zhang, Feifei; Wan, Qiang; Lu, Chenyang; Peng, Mingjing; Liao, Jiali; Yang, Yuanyou; Wang, Lumin; Liu, Ning

2016-12-01

Reactive gas pulse (RGP) sputtering approach was used to prepare TiN thin films through periodically changing the N2/Ar gas flow ratio. The obtained RGPsbnd TiN film possessed a hybrid architecture containing compositionally graded and multilayered structures, composed of hcp Ti-phase and fcc TiN-phase sublayers. Meanwhile, the RGP-TiN film exhibited a composition-oscillation along the film thickness direction, where the Ti-phase sublayer had a compositional gradient and the TiN-phase retained a constant stoichiometric ratio of Ti:N ≈ 1. The film modulation ratio λ (the thicknesses ratio of the Ti and TiN-phase sublayer) can be effectively tuned by controlling the undulation behavior of the N2 partial flow rate. Detailed analysis showed that this hybrid structure originated from a periodic transition of the film growth mode during the reactive sputtering process.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verma, Shweta, E-mail: shwetaverma@rrcat.gov.in; Rao, B. T.; Detty, A. P.

We studied localized surface plasmon resonances (LSPR) at different compositions, substrate temperatures, and mass thicknesses of Ag-Au alloy nanoparticle films grown by sequential pulsed laser deposition. The LSPRs were pronounced at all compositions of the films grown at high substrate temperature of about 300 °C as compared to those grown at room temperature. The alloy formation and composition of the films were determined using X-ray photoelectron and energy dispersive spectroscopy. Films' mass thickness and compositional uniformity along the thickness were determined using X-ray reflectometry and secondary ion mass spectroscopy. Atomic force microscopic analysis revealed the formation of densely packed nanoparticles ofmore » increasing size with the number of laser ablation pulses. The LSPR wavelength red shifted with increasing either Au percentage or film mass thickness and corresponding LSPR tuning was obtained in the range of 450 to 690 nm. The alloy dielectric functions obtained from three different models were compared and the optical responses of the nanoparticle films were calculated from modified Yamaguchi effective medium theory. The tuning of LSPR was found to be due to combined effect of change in intrinsic and extrinsic parameters mainly the composition, morphology, particle-particle, and particle-substrate interactions.« less

High Dielectric Performance of Solution-Processed Aluminum Oxide-Boron Nitride Composite Films

NASA Astrophysics Data System (ADS)

Yu, Byoung-Soo; Ha, Tae-Jun

2018-04-01

The material compositions of oxide films have been extensively investigated in an effort to improve the electrical characteristics of dielectrics which have been utilized in various electronic devices such as field-effect transistors, and storage capacitors. Significantly, solution-based compositions have attracted considerable attention as a highly effective and practical technique to replace vacuum-based process in large-area. Here, we demonstrate solution-processed composite films consisting of aluminum oxide (Al2O3) and boron nitride (BN), which exhibit remarkable dielectric properties through the optimization process. The leakage current of the optimized Al2O3-BN thin films was decreased by a factor of 100 at 3V, compared to pristine Al2O3 thin film without a loss of the dielectric constant or degradation of the morphological roughness. The characterization by X-ray photoelectron spectroscopy measurements revealed that the incorporation of BN with an optimized concentration into the Al2O3 dielectric film reduced the density of oxygen vacancies which act as defect states, thereby improving the dielectric characteristics.

Effect of annealing temperature on the structural, morphological, and mechanical properties of polycrystalline zirconium oxynitride composite films deposited by plasma focus device

NASA Astrophysics Data System (ADS)

Khan, Ijaz A.; Kashif, Muhammad; Farid, Amjad; Rawat, Rajdeep S.; Ahmad, Riaz

2017-12-01

In this article, we reveal the post deposition annealing effect on the structural, morphological, and mechanical properties of polycrystalline zirconium oxynitride (P-ZrON) composite films deposited for 40 focus shots using a plasma focus device. The development of Zr(101), ZrN(111), ZrN(200), Zr3N4(320), ZrN0.28(002), and m-ZrO2(200) diffraction peaks confirms the deposition of P-ZrON composite films. The peak intensity, crystallite size, dislocation density, compressive stress, and texture coefficient of the Zr3N4(320) plane and the microstructural features such as the shape, size and distribution of nanoparticles as well as the film compactness are influenced by the annealing temperature. Elemental analysis confirms the presence of Zr, N, and O in the deposited films. The microhardness of the P-ZrON composite film annealed at 500 °C is found to be 11.87 GPa which is 7.8 times that of virgin zirconium.

Fabrication and optical nonlinearities of composite films derived from the water-soluble Keplerate-type polyoxometalate and chloroform-soluble porphyrin.

PubMed

Shi, Zonghai; Zhou, Yunshan; Zhang, Lijuan; Yang, Di; Mu, Cuncun; Ren, Haizhou; Shehzad, Farooq Khurum; Li, Jiaqi

2015-03-07

Composite films derived from the water-soluble Keplerate-type polyoxometalate (NH4)42[Mo132O372(CH3COO)30(H2O)72]·ca. 300H2O·ca. 10CH3COONH4 (denoted (NH4)42{Mo132}) and chloroform-soluble tetraphenylporphyrin perchlorate [H2TPP](ClO4)2 are successfully fabricated by a layer-by-layer self-assembly method and characterized by UV-vis spectroscopy and X-ray photoelectron spectroscopy (XPS). The structure of the {Mo132} and [H2TPP](2+) in the films remain intact in light of the results of UV-vis spectroscopy and XPS. UV-vis spectra measurements reveal that the amounts of deposition of {Mo132} and [H2TPP](2+) remain constant in every adsorption cycle in the composite films assembly process. Nonlinear optical properties of the composite films have been investigated by using the Z-scan technique at a wavelength of 532 nm and pulse width of 7 ns. The results show that the composite films have notable nonlinear saturated absorption and self-defocusing effects. The combination of {Mo132} with [H2TPP](2+) can result in composite films with remarkably enhanced optical nonlinearities. The interfacial charge transfer induced by laser from porphyrin to POM in the films is thought to play a key role in the enhancement of NLO response. The third-order NLO susceptibility χ((3)) of the composite films increases with the increase of film thickness.

Properties of polyvinyl alcohol/xylan composite films with citric acid.

PubMed

Wang, Shuaiyang; Ren, Junli; Li, Weiying; Sun, Runcang; Liu, Shijie

2014-03-15

Composite films of xylan and polyvinyl alcohol were produced with citric acid as a new plasticizer or a cross-linking agent. The effects of citric acid content and polyvinyl alcohol/xylan weight ratio on the mechanical properties, thermal stability, solubility, degree of swelling and water vapor permeability of the composite films were investigated. The intermolecular interactions and morphology of composite films were characterized by FTIR spectroscopy and SEM. The results indicated that polyvinyl alcohol/xylan composite films had good compatibility. With an increase in citric acid content from 10% to 50%, the tensile strength reduced from 35.1 to 11.6 MPa. However, the elongation at break increased sharply from 15.1% to 249.5%. The values of water vapor permeability ranged from 2.35 to 2.95 × 10(-7)g/(mm(2)h). Interactions between xylan and polyvinyl alcohol in the presence of citric acid become stronger, which were caused by hydrogen bond and ester bond formation among the components during film forming. Copyright © 2013. Published by Elsevier Ltd.

Preparation of Surlyn films reinforced with cellulose nanofibres and feasibility of applying the transparent composite films for organic photovoltaic encapsulation

PubMed Central

Lertngim, Anantaya; Phiriyawirut, Manisara; Yuwawech, Kitti; Sangkhun, Weradesh; Kumnorkaew, Pisist; Muangnapoh, Tanyakorn

2017-01-01

This research concerns the development of Surlyn film reinforced with micro-/nanofibrillated celluloses (MFC) for use as an encapsulant in organic photovoltaic (OPV) cells. The aim of this work was to investigate the effects of fibre types and the mixing methods on the structure–properties of the composite films. Three types of cellulose micro/nanofibrils were prepared: the as-received MFC, the dispersed MFC and the esterified MFC. The fibres were mixed with Surlyn via an extrusion process, using two different mixing methods. It was found that the extent of fibre disintegration and tensile modulus of the composite films prepared by the master-batching process was superior to that of the composite system prepared by the direct mixing method. Using the esterified MFC as a reinforcement, compatibility between polymer and the fibre increased, accompanied with the improvement of the percentage elongation of the Surlyn composite film. The percentage of light transmittance of the Surlyn/MFC films was above 88, regardless of the fibre types and fibre concentrations. The water vapour transmission rate of the Surlyn/esterified MFC film was 65% lower than that of the neat Surlyn film. This contributed to the longer lifetime of the OPV encapsulated with the Surlyn/esterified MFC film. PMID:29134083

Preparation of Surlyn films reinforced with cellulose nanofibres and feasibility of applying the transparent composite films for organic photovoltaic encapsulation

NASA Astrophysics Data System (ADS)

Lertngim, Anantaya; Phiriyawirut, Manisara; Wootthikanokkhan, Jatuphorn; Yuwawech, Kitti; Sangkhun, Weradesh; Kumnorkaew, Pisist; Muangnapoh, Tanyakorn

2017-10-01

This research concerns the development of Surlyn film reinforced with micro-/nanofibrillated celluloses (MFC) for use as an encapsulant in organic photovoltaic (OPV) cells. The aim of this work was to investigate the effects of fibre types and the mixing methods on the structure-properties of the composite films. Three types of cellulose micro/nanofibrils were prepared: the as-received MFC, the dispersed MFC and the esterified MFC. The fibres were mixed with Surlyn via an extrusion process, using two different mixing methods. It was found that the extent of fibre disintegration and tensile modulus of the composite films prepared by the master-batching process was superior to that of the composite system prepared by the direct mixing method. Using the esterified MFC as a reinforcement, compatibility between polymer and the fibre increased, accompanied with the improvement of the percentage elongation of the Surlyn composite film. The percentage of light transmittance of the Surlyn/MFC films was above 88, regardless of the fibre types and fibre concentrations. The water vapour transmission rate of the Surlyn/esterified MFC film was 65% lower than that of the neat Surlyn film. This contributed to the longer lifetime of the OPV encapsulated with the Surlyn/esterified MFC film.

Preparation and properties of biodegradable films from Sterculia urens short fiber/cellulose green composites.

PubMed

Jayaramudu, J; Reddy, G Siva Mohan; Varaprasad, K; Sadiku, E R; Sinha Ray, S; Varada Rajulu, A

2013-04-02

The development of commercially viable "green products", based on natural resources for the matrices and reinforcements, in a wide range of applications, is on the rise. The present paper focuses on Sterculia urens short fiber reinforced pure cellulose matrix composite films. The morphologies of the untreated and 5% NaOH (alkali) treated S. urens fibers were observed by SEM. The effect of 5% NaOH treated S. urens fiber (5, 10, 15 and 20% loading) on the mechanical properties and thermal stability of the composites films is discussed. This paper presents the developments made in the area of biodegradable S. urens short fiber/cellulose (SUSF/cellulose) composite films, buried in the soil and later investigated by the (POM), before and after biodegradation has taken place. SUSF/cellulose composite films have great potential in food packaging and for medical applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

Preparation of smooth, flexible and stable silver nanowires- polyurethane composite transparent conductive films by transfer method

NASA Astrophysics Data System (ADS)

Bai, Shengchi; Wang, Haifeng; Yang, Hui; Zhang, He; Guo, Xingzhong

2018-02-01

Silver nanowires (AgNWs)-polyurethane (PU) composite transparent conductive films were fabricated via transfer method using AgNWs conductive inks and polyurethane as starting materials, and the effects of post-treatments including heat treatment, NaCl solution bath and HCl solution bath for AgNWs film on the sheet resistance and transmittance of the composite films were respectively investigated in detail. AgNWs networks are uniformly embedded in the PU layer to improve the adhesion and reduce the surface roughness of AgNWs-PU composite films. Heat treatment can melt and weld the nanowires, and NaCl and HCl solution baths promote the dissolution and re-deposition of silver and the dissolving of the polymer, both which form conduction pathways and improve contact of AgNWs for reducing the sheet resistance. Smooth and flexible AgNWs-PU composite film with a transmittance of 85% and a sheet resistance of 15 Ω · sq‑1 is obtained after treated in 0.5 wt% HCl solution bath for 60 s, and the optoelectronic properties of the resultant composite film can maintain after 1000 cycles of bending and 100 days.

Development and characterization of an edible composite film based on chitosan and virgin coconut oil with improved moisture sorption properties.

PubMed

Binsi, P K; Ravishankar, C N; Srinivasa Gopal, T K

2013-04-01

An edible composite film was prepared from an emulsion system based on chitosan and virgin coconut oil (VCO). The effect of incorporation of VCO was evaluated at various concentrations and the optimum concentration was chosen based on resultant changes in the properties of the film. Addition of VCO in film forming solution resulted in increase in film thickness and marginal reduction in film transparency. Compatibility of VCO with chitosan was better at lower concentration of VCO as indicated by the microstructure of composite film in scanning electron micrographs. Phase separation was evident at higher level of oil incorporation and the optimal oil/chitosan ratio was determined to be at 0.5 to 1 mL/g chitosan. Furthermore, chemical interaction took place between VCO and chitosan as revealed by Fourier transform infrared spectroscopy data. Even though control chitosan films exhibited superior gas barrier properties, composite film with optimum VCO concentration revealed better mechanical and moisture sorption properties. © 2013 Institute of Food Technologists®

Effect of interface structure regulation caused by variation of imidization rate on conduction current characteristics of PI/nano-Al2O3 three-layer composite films

NASA Astrophysics Data System (ADS)

Ma, Xinyu; Liu, Lizhu; Zhang, Xiaorui; He, Hongju

2018-06-01

A series of sandwich structure PI films were prepared by different imidization process, with pure PI film as the interlayer and PI/Al2O3 composite films as outer layers. The imidization rate of the film with different cured processes was calculated by characterizing by infrared spectrum (FT-IR), and the morphology of interlayer interface with different imidization rates by scanning electron microscope (SEM). When the imidization conditions of the first and second films were 260 °C/120 min, the composite films displayed better interface structure and higher imidization rate (ID) than others. Moreover, results also showed that the conduction current of three-layer composite film steadily improved with increased ID and temperature, and was higher than that of the pure film. At the temperature of 30 °C, the electrical aging threshold at different ID was obtained. When the ID reached the maximum value of 78.9%, the electrical aging threshold reached the maximum 41.69 kV/mm.

Substrate bias effects on composition and coercivity of CoCrTa/Cr thin films on canasite and glass

NASA Astrophysics Data System (ADS)

Deng, Y.; Lambeth, D. N.; Sui, X.; Lee, L.-L.; Laughlin, D. E.

1993-05-01

CoCrTa/Cr thin films were prepared by rf diode sputtering onto canasite and glass substrates at various bias voltages from two targets of different compositions (Co82.8Cr14.6Ta2.6 and Co86Cr12Ta2). While Auger depth profile analysis indicates that there is some broadening at the CoCrTa-Cr interface, x-ray fluorescence spectroscopy reveals that changes in alloy composition due to the resputtering processes are even more prominent. For both targets, as the substrate bias increases the Co content in the films declines, and the magnetization decreases. The maximum film coercivity appears to correlate to the final film composition. By investigating the results from both targets, it is concluded that the coercivity reaches a maximum when the film composition is in the neighborhood of Co84Cr13Ta3. Thus, to optimize the coercivity different bias voltages are required for each target. Excessive substrate bias, however, leads to films with low magnetization and coercivity.

Electrical and optical percolations in PMMA/GNP composite films

NASA Astrophysics Data System (ADS)

Arda, Ertan; Mergen, Ömer Bahadır; Pekcan, Önder

2018-05-01

Effects of graphene nanoplatelet (GNP) addition on the electrical conductivity and optical absorbance of poly(methyl methacrylate)/graphene nanoplatelet (PMMA/GNP) composite films were studied. Optical absorbance and two point probe resistivity techniques were used to determine the variations of the optical and electrical properties of the composites, respectively. Absorbance intensity, A, and surface resistivity, Rs, of the composite films were monitored as a function of GNP mass fraction (M) at room temperature. Absorbance intensity values of the composites were increased and surface resistivity values were decreased by increasing the content of GNP in the composite. Electrical and optical percolation thresholds of composite films were determined as Mσ = 27.5 wt.% and Mop = 26.6 wt.%, respectively. The conductivity and the optical results were attributed to the classical and site percolation theories, respectively. Optical (βop) and electrical (βσ) critical exponents were calculated as 0.40 and 1.71, respectively.

Through-thickness thermal conductivity enhancement of graphite film/epoxy composite via short duration acidizing modification

NASA Astrophysics Data System (ADS)

Wang, Han; Wang, Shaokai; Lu, Weibang; Li, Min; Gu, Yizhou; Zhang, Yongyi; Zhang, Zuoguang

2018-06-01

Graphite films have excellent in-plane thermal conductivity but extremely low through-thickness thermal conductivity because of their intrinsic inter-layer spaces. To improve the inter-layer heat transfer of graphite films, we developed a simple interfacial modification with a short duration mixed-acid treatment. The effects of the mixture ratio of sulfuric and nitric acids and treatment time on the through-thickness thermal properties of graphite films were studied. The modification increased the through-thickness thermal conductivity by 27% and 42% for the graphite film and its composite, respectively. X-ray photoelectron spectroscopy, X-ray powder diffraction, and scanning electron microscopy results indicated that the acidification process had two competing effects: the positive contribution made by the enhanced interaction between the graphite layers induced by the functional groups and the negative effect from the destruction of the graphite layers. As a result, an optimal acidification method was found to be sulfuric/nitric acid treatment with a mixture ratio of 3:1 for 15 min. The resultant through-thickness thermal conductivity of the graphite film could be improved to 0.674 W/mK, and the corresponding graphite/epoxy composite shows a through-thickness thermal conductivity of 0.587 W/mK. This method can be directly used for graphite films and their composite fabrication to improve through-thickness thermal conductivity.

Effect of TiO2 nanoparticles doping on structural and electrical properties of PVA: NaBr polymer electrolyte

NASA Astrophysics Data System (ADS)

Sagar, Rohan N.; Ravindrachary, V.; Guruswamy, B.; Hegde, Shreedatta; Mahanthesh, B. K.; Kumari, R. Padma

2018-05-01

The effect of TiO2 nanoparticles on morphology and electrical properties of PVA: NaBr composite films were carried out using various techniques. The pure and TiO2 nanoparticle doped PVA: NaBr composite films were prepared using solvent casting method. The FTIR spectral studies shows that the Ti+ ions of TiO2 interacts with hydroxyl group (OH) of PVA via hydrogen bonding and forms the charge transfer complexes (CTC). These interactions are of inter/intra molecular type and affects the surface morphology as well as the electrical properties of composite films. XRD study shows that the crystallinity of the composite increases with doping level. SEM studies shows that the increase in roughness of the surface of the composite films and uniform dispersion of nanofillers in polymer matrix. Electrical properties are analyzed using impedance analyzer and higher conductivity (10-4Scm-1) is achieved for 5 wt % TiO2 doping concentration.

Functionalized low defect graphene nanoribbons and polyurethane composite film for improved gas barrier and mechanical performances.

PubMed

Xiang, Changsheng; Cox, Paris J; Kukovecz, Akos; Genorio, Bostjan; Hashim, Daniel P; Yan, Zheng; Peng, Zhiwei; Hwang, Chih-Chau; Ruan, Gedeng; Samuel, Errol L G; Sudeep, Parambath M; Konya, Zoltan; Vajtai, Robert; Ajayan, Pulickel M; Tour, James M

2013-11-26

A thermoplastic polyurethane (TPU) composite film containing hexadecyl-functionalized low-defect graphene nanoribbons (HD-GNRs) was produced by solution casting. The HD-GNRs were well distributed within the polyurethane matrix, leading to phase separation of the TPU. Nitrogen gas effective diffusivity of TPU was decreased by 3 orders of magnitude with only 0.5 wt % HD-GNRs. The incorporation of HD-GNRs also improved the mechanical properties of the composite films, as predicted by the phase separation and indicated by tensile tests and dynamic mechanical analyses. The improved properties of the composite film could lead to potential applications in food packaging and lightweight mobile gas storage containers.

Effect of Gallic acid on mechanical and water barrier properties of zein-oleic acid composite films.

PubMed

Masamba, Kingsley; Li, Yue; Hategekimana, Joseph; Liu, Fei; Ma, Jianguo; Zhong, Fang

2016-05-01

In this study, the effect of gallic acid on mechanical and water barrier properties of zein-oleic acid 0-4 % composite films was investigated. Molecular weight distribution analysis was carried out to confirm gallic acid induced cross linking through change in molecular weight in fraction containing zein proteins. Results revealed that gallic acid treatment increased tensile strength from 17.9 MPa to 26.0 MPa, decreased water vapour permeability from 0.60 (g mm m(-2) h(-1) kPa(-1)) to 0.41 (g mm m(-2) h(-1) kPa(-1)), increased solubility from 6.3 % to 10.2 % and marginally increased elongation at break from 3.7 % to 4.2 % in zein films only. However, gallic acid treatment in zein-oleic composite films did not significantly influence mechanical and water barrier properties and in most instances irrespective of oleic acid concentration, the properties were negatively affected. Results from scanning electron microscopy showed that both gallic acid treated and untreated zein films and composite films containing 3 % oleic acid had a compact and homogeneous structure while those containing 4 % oleic acid had inhomogeneous structure. The findings have demonstrated that gallic acid treatment can significantly improve mechanical and water barrier properties especially in zein films only as opposed to when used in composite films using zein and oleic acid.

Hysteresis heating based induction bonding of composite materials

NASA Astrophysics Data System (ADS)

Suwanwatana, Witchuda

The viability of using magnetic particulate susceptor materials for induction heating during bonding of polymer matrix composites is well established in this work. The unique ability to offer localized heating, geometric flexibility, and self-controlled temperature is the major advantage of this technique. Hysteresis heating is tailored through careful design of the microstructure of nickel particulate polymer films (Ni/PSU). An excellent heating rate can be attained in the frequency range of 1 to 10 MHz for particle volume fraction below percolation of 0.26. The diameter of nickel particle should be kept between 65 nm to 10 mum to ensure multi-domain heating, Curie temperature control, negligible shielding effect, minimum eddy current, and slight particle oxidation. The hysteresis heating behavior of the Ni/PSU films is found to be volumetric in nature and proportional to the cube of applied magnetic field. On the other hand, heat generation is inversely proportional to the size of the multi-domain particles. The frequency effect; however, provide maximum heat generation at the domain wall resonance frequency. Curie temperature control is observed when sufficiently high magnetic fields (˜138 Oe) are applied. The master curves of AC heat generation in Ni/PSU films are established and show a strong particle size effect. Hysteresis fusion bonding of glass/polyphenylene sulfide thermoplastic composites using a magnetic film as the thermoplastic adhesive shows that the bond strength of hysteresis-welded materials is comparable to that of autoclave-welded materials while offering an order of magnitude reduction in cycle time. The relative contribution of the intimate contact and healing mechanisms to the fusion bonding process indicates that hysteresis bonding is controlled by intimate contact. The macroscopic failure modes vary from mostly adhesive composite/film (low bond strength) to a combination of adhesive composite/film, cohesive film, cohesive composite and mostly cohesive composite (high bond strength). Inspection of the microscopic failure at the nickel particle/polymer interface in the film indicates quasi-brittle failure mode. The amount of adhesive failure increases with decreasing particle size and increasing particle volume fraction. The XPS peaks confirm nickel oxide in the form of NiO on the failure surface of particle/polymer debonding of hysteresis susceptor film.

Fiber optic humidity sensor based on the graphene oxide/PVA composite film

NASA Astrophysics Data System (ADS)

Wang, Youqing; Shen, Changyu; Lou, Weimin; Shentu, Fengying

2016-08-01

Fiber optic humidity sensor based on an in-fiber Mach-Zehnder interferometer (MZI) coated with graphene oxide (GO)/PVA composite film was investigated. The MZI is constructed of two waist-enlarged tapers. The length between two waist-enlarged tapers is 20 mm. By comparing the experiment results of MZI coated with different GO/PVA composite films, composite film formed by the ratio of 0.3 g PVA mixed with 10 ml GO dispersion shows a better performance of relative humidity sensing. By using the molecular structure model of the composited GO/PVA, the operation mechanism between GO/PVA composite film and water molecules was illustrated. The sensitivity of 0.193 dB/%RH with a linear correlation coefficient of 99.1% and good stability under the relative humidity range of 25-80% was obtained. Temperature effect on the proposed fiber optic humidity sensor was also considered and analyzed. According to the repetitive experimental results, the proposed humidity sensor shows a good repeatability.

Properties of cellulose/Thespesia lampas short fibers bio-composite films.

PubMed

Ashok, B; Reddy, K Obi; Madhukar, K; Cai, J; Zhang, L; Rajulu, A Varada

2015-01-01

Cellulose was dissolved in pre cooled environment friendly solvent (aq.7% sodium hydroxide+12% urea) and regenerated with 5%H2SO4 as coagulation bath. Using cellulose as matrix and alkali treated short natural fibers extracted from the newly identified Thespesia lampas plant as fillers the green composite films were prepared. The films were found to be non toxic. The effect of fiber loading on the tensile properties and thermal stability was studied. The fractographs indicated better interfacial bonding between the fibers and cellulose. The crystallinity of the composite films was found to be lower than the matrix and decreased with increasing fiber content. In spite of better interfacial bonding, the tensile properties of the composites were found to be lower than those of the matrix and decreased with increasing fiber content and this behavior was attributed to the random orientation of the fibers in the composites. The thermal stability of the composite films was higher than the matrix and increased with fiber content. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of slurry composition on the chemical mechanical polishing of thin diamond films

NASA Astrophysics Data System (ADS)

Werrell, Jessica M.; Mandal, Soumen; Thomas, Evan L. H.; Brousseau, Emmanuel B.; Lewis, Ryan; Borri, Paola; Davies, Philip R.; Williams, Oliver A.

2017-12-01

Nanocrystalline diamond (NCD) thin films grown by chemical vapour deposition have an intrinsic surface roughness, which hinders the development and performance of the films' various applications. Traditional methods of diamond polishing are not effective on NCD thin films. Films either shatter due to the combination of wafer bow and high mechanical pressures or produce uneven surfaces, which has led to the adaptation of the chemical mechanical polishing (CMP) technique for NCD films. This process is poorly understood and in need of optimisation. To compare the effect of slurry composition and pH upon polishing rates, a series of NCD thin films have been polished for three hours using a Logitech Ltd. Tribo CMP System in conjunction with a polyester/polyurethane polishing cloth and six different slurries. The reduction in surface roughness was measured hourly using an atomic force microscope. The final surface chemistry was examined using X-ray photoelectron spectroscopy and a scanning electron microscope. It was found that of all the various properties of the slurries, including pH and composition, the particle size was the determining factor for the polishing rate. The smaller particles polishing at a greater rate than the larger ones.

Electrodeposition of MWNT/Bi2Te3 Composite Thermoelectric Films

NASA Astrophysics Data System (ADS)

Xu, Han; Wang, Wei

2013-07-01

The effect of multiwalled carbon nanotubes (MWNTs) on the electrochemical behavior of the Bi-Te binary system in nitric acid baths was investigated by means of cyclic voltammetry and electrochemical impedance spectroscopy. Based on the results, MWNT/Bi2Te3 composite thermoelectric films were prepared by potentiostatic electrodeposition at room temperature. The morphology, composition, and structure of the MWNT/Bi2Te3 composite films were analyzed by environmental scanning electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction. The results show that addition of MWNTs to the electrolyte did not change the electrochemical reduction mechanisms of Bi3+, HTeO{2/+} or their mixture, but the reduction processes of Bi3+, HTeO{2/+}, and their mixture become easier. MWNT/Bi2Te3 composite thermoelectric films can be obtained by potentiostatic electrodeposition at a wide range of potentials with subsequent annealing. The MWNTs in the films act as nucleation sites for Bi2Te3 compound and thereby elevate the film deposition rate. The content of Bi element and MWNTs in the films increased as the potential was shifted negatively. In addition, the MWNTs can enhance the crystallization of Bi2Te3 film.

Effect of adjustable molecular chain structure and pure silica zeolite nanoparticles on thermal, mechanical, dielectric, UV-shielding and hydrophobic properties of fluorinated copolyimide composites

NASA Astrophysics Data System (ADS)

Li, Qing; Liao, Guangfu; Zhang, Shulai; Pang, Long; Tong, Hao; Zhao, Wenzhe; Xu, Zushun

2018-01-01

A series of polyimide (PI) films, polyimide/pure silica zeolite nanoparticles (PSZN) blend films and polyimide/amine-functionalized pure silica zeolite nanoparticles (APSZN) composite films were successfully prepared by random copolycondensation. Thereinto, PSZN were synthesized by hydrothermal method. The polyimides were derived from 4,4‧-diaminodiphenyl ether (ODA), and three adjustable molar ratios (3:1, 1:1, 1:3) of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl] propane dianhydride (BPADA) and 4,4‧-(hexafluoroisopropylidene) diphthalic anhydride (6FDA). The effects of PSZN, APSZN and different chain structure on PI films were specifically evaluated in terms of morphology, thermal, mechanical, dielectric and UV-shielding properties, etc. Comparison was given among pure PI flims, PI/PSZN blend films and PI/APSZN composite flims. The results showed that the thermal and mechanical properties of PI films were drastically impaired after adding PSZN. On the contrary, the strength, toughness and thermal stability were improved after adding APSZN. Moreover, the dielectric constants of the PI/APSZN composite flims were lowered but UV-shielding properties were enhanced. Interestingly, we found that the greatest effects were obtained through introducing APSZN in PI derived by the 1:1 ratio of BPADA:6FDA. The corresponding PI/APSZN composite flim exhibited the most reinforced and toughened properties, the largest decrement of dielectric constant and the best UV-shielding efficiency, which made the composite flim be used as ultraviolet shielding material in outer space filled with high temperature and intensive ultraviolet light. Meanwhile, this work also provided a facile way to synthesize composite materials with adjustable performance.

Elastic Moduli of Nanoparticle-Polymer Composite Thin Films via Buckling on Elastomeric Substrates

NASA Astrophysics Data System (ADS)

Yuan, Hongyi; Karim, Alamgir; University of Akron Team

2011-03-01

Polymeric thin films find applications in diverse areas such as coatings, barriers and packaging. The dispersion of nanoparticles into the films was proven to be an effective method to generate tunable properties, particularly mechanical strength. However, there are very few methods for mechanical characterization of the composite thin films with high accuracy. In this study, nanometric polystyrene and polyvinyl alcohol films with uniformly dispersed cobalt and Cloisite nanoparticles at varying concentrations were synthesized via flow-coating and then transferred to crosslinked polydimethylsiloxane (PDMS) flexible substrates. The technique of Strain-Induced Elastic Buckling Instability for Mechanical Measurements (SIEBIMM) was employed to determine the elastic moduli of the films, which were calculated from the buckling patterns generated by applying compressive stresses. Results on moduli of films as a function of the concentrations of nanoparticles and the thicknesses of the composite films will be presented. *Corresponding author: alamgir@uakron.edu

New intelligent multifunctional SiO2/VO2 composite films with enhanced infrared light regulation performance, solar modulation capability, and superhydrophobicity

NASA Astrophysics Data System (ADS)

Wang, Chao; Zhao, Li; Liang, Zihui; Dong, Binghai; Wan, Li; Wang, Shimin

2017-12-01

Highly transparent, energy-saving, and superhydrophobic nanostructured SiO2/VO2 composite films have been fabricated using a sol-gel method. These composite films are composed of an underlying infrared (IR)-regulating VO2 layer and a top protective layer that consists of SiO2 nanoparticles. Experimental results showed that the composite structure could enhance the IR light regulation performance, solar modulation capability, and hydrophobicity of the pristine VO2 layer. The transmittance of the composite films in visible region (Tlum) was higher than 60%, which was sufficient to meet the requirements of glass lighting. Compared with pristine VO2 films and tungsten-doped VO2 film, the near IR control capability of the composite films was enhanced by 13.9% and 22.1%, respectively, whereas their solar modulation capability was enhanced by 10.9% and 22.9%, respectively. The water contact angles of the SiO2/VO2 composite films were over 150°, indicating superhydrophobicity. The transparent superhydrophobic surface exhibited a high stability toward illumination as all the films retained their initial superhydrophobicity even after exposure to 365 nm light with an intensity of 160 mW.cm-2 for 10 h. In addition, the films possessed anti-oxidation and anti-acid properties. These characteristics are highly advantageous for intelligent windows or solar cell applications, given that they can provide surfaces with anti-fogging, rainproofing, and self-cleaning effects. Our technique offers a simple and low-cost solution to the development of stable and visible light transparent superhydrophobic surfaces for industrial applications.

Nacre-mimic Reinforced Ag@reduced Graphene Oxide-Sodium Alginate Composite Film for Wound Healing.

PubMed

Yan, Xu; Li, Fei; Hu, Kang-Di; Xue, Jingzhe; Pan, Xiao-Feng; He, Tao; Dong, Liang; Wang, Xiang-Ying; Wu, Ya-Dong; Song, Yong-Hong; Xu, Wei-Ping; Lu, Yang

2017-10-23

With the emerging of drug-resistant bacterial and fungal pathogens, there raise the interest of utilizing versatile antimicrobial biomaterials to treat the acute wound. Herein, we report the spraying mediated assembly of a bio-inspired Ag@reduced graphene-sodium alginate (AGSA) composite film for effective wound healing. The obtained film displayed lamellar microstructures similar to the typical "brick-and-mortar" structure in nacre. In this nacre-mimic structure, there are abundant interfacial interactions between nanosheets and polymeric matrix, leading to remarkable reinforcement. As a result, the tensile strength, toughness and Young's modulus have been improved 2.8, 2.3 and 2.7 times compared with pure sodium alginate film, respectively. In the wound healing study, the AGSA film showed effective antimicrobial activities towards Pseudomonas aeruginosa, Escherichia coli and Candida albicans, demonstrating the ability of protecting wound from pathogenic microbial infections. Furthermore, in vivo experiments on rats suggested the effect of AGSA film in promoting the recovery of wound sites. According to MTT assays, heamolysis evaluation and in vivo toxicity assessment, the composite film could be applied as a bio-compatible material in vitro and in vivo. Results from this work indicated such AGSA film has promising performance for wound healing and suggested great potential for nacre-mimic biomaterials in tissue engineering applications.

Novel green nano composites films fabricated by indigenously synthesized graphene oxide and chitosan.

PubMed

Khan, Younus H; Islam, Atif; Sarwar, Afsheen; Gull, Nafisa; Khan, Shahzad M; Munawar, Muhammad A; Zia, Saba; Sabir, Aneela; Shafiq, Muhammad; Jamil, Tahir

2016-08-01

Graphene oxide (GO) was indigenously synthesized from graphite using standard Hummers method. Chitosan-graphene oxide green composite films were fabricated by mixing aqueous solution of chitosan and GO using dilute acetic acid as a solvent for chitosan. Chitosan of different viscosity and calculated molecular weight was used keeping amount of GO constant in each composite film. The structural properties, thermal stability and mechanical properties of the composite films were investigated using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and tensile test. FTIR studies revealed the successful synthesis of GO from graphite powder and it was confirmed that homogenous blending of chitosan and GO was promising due to oxygenated functional groups on the surface of GO. XRD indicated effective conversion of graphite to GO as its strong peak observed at 11.06° as compared to pristine graphite which appeared at 26°. Moreover, mechanical analysis confirmed the effect of molecular weight on the mechanical properties of chitosan-GO composites showing that higher molecular weight chitosan composite (GOCC-1000) showed best strength (higher than 3GPa) compared to other composite films. Thermal stability of GOCC-1000 was enhanced for which residual content increased up to 56% as compared to the thermal stability of GOCC-200 whose residue was restricted to only 24%. The morphological analysis of the composites sheets by SEM was smooth having dense structure and showed excellent interaction, miscibility, compatibility and dispersion of GO with chitosan. The prepared composite films find their applications as biomaterials in different biomedical fields. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of assistant rf field on phase composition of iron nitride film prepared by magnetron sputtering process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, W.L.; Zheng, F.; Fei, W.D.

2006-01-15

Fe-N thin films were fabricated using a direct current magnetron sputtering process assisted by a radio-frequency (rf) field. The effect of the rf field on the phase composition of the films was investigated. The results indicate that with the assistance of the rf field, various kinds of iron nitrides can be obtained in the films, including {alpha}{sup '}-Fe-N, {alpha}{sup ''}-Fe{sub 16}N{sub 2}, {xi}-Fe{sub 2}N, {epsilon}-Fe{sub 3}N, and {gamma}{sup ''}-FeN with ZnS structure. It was found that the rf field greatly benefits the formation of iron nitrides in the Fe-N films.

Investigation of polypyrrole/polyvinyl alcohol-titanium dioxide composite films for photo-catalytic applications

NASA Astrophysics Data System (ADS)

Cao, Shaoqiang; Zhang, Hongyang; Song, Yuanqing; Zhang, Jianling; Yang, Haigang; Jiang, Long; Dan, Yi

2015-07-01

Polypyrrole/polyvinyl alcohol-titanium dioxide (PPy/PVA-TiO2) composite films used as photo-catalysts were fabricated by combining TiO2 sol with PPy/PVA solution in which PPy was synthesized by in situ polymerization of pyrrole (Py) in polyvinyl alcohol (PVA) matrix and loaded on glass. The prepared photo-catalysts were investigated by X-ray diffraction (XRD), ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectra and photoluminescence (PL). The results indicate that the composites have same crystal structure as the TiO2 and extend the optic absorption from UV region to visible light region. By detecting the variation ratio, detected by ultraviolet-vis spectroscopy, of model pollutant rhodamine B (RhB) solution in the presence of the composite films under both UV and visible light irradiation, the photo-catalytic performance of the composite films was investigated. The results show that the PPy/PVA-TiO2 composite films show better photo-catalytic properties than TiO2 film both under UV and visible light irradiation, and the photo-catalytic degradation of RhB follows the first-order kinetics. The effects of the composition of composite films and the concentration of RhB on the photo-catalytic performance, as well as the possible photo-catalytic mechanism, were also discussed. By photo-catalytic recycle experiments, the structure stability of the PPy/PVA-TiO2 composite film was investigated and the results show that the photo-catalytic activity under both UV and visible light irradiation have no significant decrease after four times of recycle experiments, suggesting that the photo-catalyst film is stable during the photo-catalytic process, which was also confirmed by the XRD pattern and FT-IR spectra of the composite film before and after photo-catalytic.

Layer-by-layer composite film of nickel phthalocyanine and montmorillonite clay for synergistic effect on electrochemical detection of dopamine

NASA Astrophysics Data System (ADS)

de Lucena, Nathalia C.; Miyazaki, Celina M.; Shimizu, Flávio M.; Constantino, Carlos J. L.; Ferreira, Marystela

2018-04-01

Dopamine (DA) abnormal levels are related to diseases which makes important the development of fast, reliable, low-cost and sensitive devices for diagnosis and pharmaceutical controls. Nanostructured film composite of sodium montmorillonite clay (Na+MMT) and nickel phthalocyanine (NiTsPc) was self-assembled by layer-by-layer (LbL) technique and applied as electrochemical sensor for DA in the presence of common natural interferents as ascorbic acid (AA) and uric acid (UA). Three different LbL architecture films were investigated: LbL films of clay (PEI/Na+MMT) and phthalocyanine (PEI/NiTsPc) in a bilayer structure with a conventional polyelectrolyte (PEI) and a composite film formed by both materials to verify the synergistic effect in the LbL film in a quadri-layer assembly (PEI/Na+MMT/PEI/NiTsPc). Structural characterization indicated molecular level interactions between the layers forming the LbL films. The ITO/(PEI/Na+MMT/PEI/NiTsPc)10 electrode exhibited a LOD of 1.0 μmol L-1 and linear range 5-150 μmol L-1.

Optical, mechanical and structural properties of PMMA/SiO2 nanocomposite thin films

NASA Astrophysics Data System (ADS)

Soni, Gyanesh; Srivastava, Subodh; Soni, Purushottam; Kalotra, Pankaj; Vijay, Y. K.

2018-01-01

We have fabricated PMMA/SiO2 nanocomposite flexible thin films of 60 μm thicknesses by using solution casting method in the presence of transverse electric field. In this paper, we have investigated the effect of SiO2 nanoparticle (NP) loading on optical and mechanical properties of the composite thin film. The SEM images show that nanocomposite thin films have a smoother and uniform morphology. The transmittance peak near 1103 cm-1 in FT-IR spectrum confirms the presence of SiO2 NPs in the composite thin film. It is observed that optical bandgap decreases with an increase in the SiO2 NP concentration. Dynamic mechanical analysis shows that presence of SiO2 NP enhances the mechanical strength of the composite thin film.

Formation of high-temperature superconductor films during the nonstationary laser heating of liquid metal carboxylate solutions

NASA Astrophysics Data System (ADS)

Borman, V. D.; Dudko, S. A.; Sinitsyn, I. V.; Troian, V. I.; Filippov, E. A.

1989-01-01

It has been shown in earlier studies that high-temperature superconductor films can be produced through the decomposition of metal (Y, Ba, Cu) carboxylates in a liquid solution film. In the present study, the effect of nonstationary laser heating on the composition and properties of the complex oxide films formed by this method is examined with reference to experimental results obtained for YBa2Cu3O(x) films. It is shown that the chemical composition and properties of films formed in metal carboxylate solutions can be controlled by varying the time of laser heating.

High Performance Piezoelectric Thin Films for Shape Control in Large Inflatable Structures

NASA Technical Reports Server (NTRS)

Neurgaonkar, R. R.; Nelson, J. G.

1999-01-01

The objective of this research and development program was to develop PbZr(1-x)Ti(x)O3 (PZT) and Pb(1-x)Ba(x)Nb2O6 (PBN) materials with large piezoelectric response which are suitable for shape control in large inflatable structures. Two approaches were to be considered: (1) direct deposition of PZT and PBN films on flexible plastic or thin metal foil substrates, and (2) deposition on Si followed by fabrication of hybrid structures on mylar or kapton. Testing in shape control concepts was carried out at JPL and based on their results, the required modifications were made in the final film compositions and deposition techniques. The program objective was to identify and then optimize piezoelectric materials for NASA shape control applications. This involved the bulk piezoelectric and photovoltaic responses and the compatibility of the thin films with appropriate substrate structures. Within the PZT system, Rockwell has achieved the highest reported piezoelectric coefficient (d(sub 33) greater than 100 pC/N) of any ceramic composition. We used this experience in piezoelectric technology to establish compositions that can effectively address the issues of this program. The performance of piezoelectric thin films depends directly on d(sub ij) and Epsilon. The challenge was to find PZT compositions that maintained high d(sub ij) and Epsilon, while also exhibiting a large photovoltaic effect and integrate thin films of this composition into the system structure necessary to meet shape control applications. During the course of this program, several PZT and PLZT compositions were identified that meet these requirements. Two such compositions were successfully used in electrical and optical actuation studies of thin film structures.

High Performance Piezoelectric Thin Films for Shape Control in Large Inflatable Structures

NASA Technical Reports Server (NTRS)

Neurgaonkar, R. R.; Nelson, J. G.

1999-01-01

The objective of this research and development program was to develop PbZr(1-x)Ti(x)O3 (PZT) and Pb(1-x)Ba(x)Nb2O6 (PBN) materials with large piezoelectric response which are suitable for shape control in large inflatable structures. Two approaches were to be considered: (1) direct deposition of PZT and PBN films on flexible plastic or thin metal foil substrates, and (2) deposition on Si followed by fabrication of hybrid structures on mylar or kapton. Testing in shape control concepts was carried out at JPL and based on their results, the required modifications were made in the final film compositions and deposition techniques. The program objective was to identify and then optimize piezoelectric materials for NASA shape control applications. This involved the bulk piezoelectric and photovoltaic responses and the compatibility of the thin films with appropriate substrate structures. Within the PZT system, Rockwell has achieved the highest reported piezoelectric coefficient (d(sub 33) greater than 100 pC/N) of any ceramic composition. We used this experience in piezoelectric technology to establish compositions that can effectively address the issues of this program. The performance of piezoelectric thin films depends directly on d(sub ij) and epsilin. The challenge was to find PZT compositions that maintained high d(sub ij) and epsilon, while also exhibiting a large photovoltaic effect and integrate thin films of this composition into the system structure necessary to meet shape control applications. During the course of this program, several PZT and PLZT compositions were identified that meet these requirements. Two such compositions were successfully used in electrical and optical actuation studies of thin film structures.

Effect of Plasticizers on Physicochemical and Mechanical Properties of Chitosan-Gelatin Films

NASA Astrophysics Data System (ADS)

Manshor, N. Mohammed; Rezali, M. I.; Jai, J.; Yahya, A.

2018-05-01

Composite chitosan-gelatin films were produced to investigate the effect of plasticizer and composition of chitosan and gelatin on physicochemical and mechanical properties of the films. The films were prepared according to ratio of chitosan: gelatin of 1:1, 1:2 and 2:1. For each film, glycerol, sorbitol and sucrose were added as plasticizer. The film forming solution was poured on a glass plate and dried for 12 hours in an oven at 60°C. The highest tensile strength was 4.04 MPa for films of ratio 2:1 plasticized with glycerol compared to sorbitol and sucrose which were 3.94 MPa and 3.84 MPa, respectively. However, films plasticized with sorbitol at ratio of 1:2 had the highest percent elongation which was 68.20%, followed by glycerol and sucrose which were 26.51% and 24.08%, respectively.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doyle, J.P.; Roy, R.A.; Cuomo, J.J.

We have investigated the effects of low energy bombardment on the microstructural, compositional, and electrical characteristics of ion beam sputtered thin films of Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub {ital x}}. During deposition, secondary bombardment of the growing film was performed using a Kaufman or ECR type ion source with energy ranging up to 125 eV. Microstructural changes have been characterized by TEM and XRD. Ion channeling has been performed to characterize the degree of orientation of the films. The effects of bombardment on the composition of the films were studied by RBS. It has been found that the use of anmore » ECR microwave oxygen ion source trained on the growing films induces as-deposited superconductivity and also play a role in the texturing of the films. The effects of ion bombardment on the critical current (J{sub {ital c}}) and temperature (T{sub {ital c}}) are also reported.« less

Effects of Polypropylene Orientation on Mechanical and Heat Seal Properties of Polymer-Aluminum-Polymer Composite Films for Pouch Lithium-Ion Batteries.

PubMed

Zeng, Fangxinyu; Chen, Jinyao; Yang, Feng; Kang, Jian; Cao, Ya; Xiang, Ming

2018-01-16

In this study, polyamide-aluminum foil-polypropylene (PA-Al-PP) composite films with different orientation status of the PP layer were prepared, and their morphology, tensile, peeling and heat seal behavior were studied. The comparative study of tensile and fracture behaviors of single-layer film of PA, Al and PP, as well as the composite films of PA-Al, PP-Al and PA-Al-PP revealed that in PA-Al-PP composite film, the PA layer with the highest tensile strength can share the tensile stress from the Al layer during stretching, while the PP layer with the lowest tensile strength can prevent further development of the small cracks on boundary of the Al layer during stretching. Moreover, the study of heat seal behavior suggested that both the orientation status and the heat seal conditions were important factors in determining the heat seal strength ( HSS ) and failure behavior of the sample. Four failure types were observed, and a clear correspondence between HSS and failure types was found. The results also elucidated that for the composite film, only in the cases where the tensile stress was efficiently released by each layer during HSS measurement could the composite film exhibit desired high HSS that was even higher than its tensile strength.

Effect of the composition on the superconducting properties of IBAD-MgO SmBCO coated conductors with superconducting film directly deposited on epi-MgO layer

NASA Astrophysics Data System (ADS)

Kim, H. S.; Oh, S. S.; Lee, N. J.; Jang, S. H.; Min, C. H.; Ha, H. S.; Chung, K. C.; Youm, D. J.; Moon, S. H.; Park, C.

2011-11-01

Sm1+xBa2-xCu3+yO7-δ (SmBCO) films were directly deposited on the epi-MgO/IBAD-MgO/Y2O3/Al2O3/Hastelloy template by co-evaporation using the evaporation using drum in dual chambers (EDDC) system without the buffer layer in order to investigate the effect of the composition ratios on superconducting property, microstructure and texture of SmBCO film. The films with gradient composition ratios of Sm:Ba:Cu were deposited using a shield with an opening which was placed between the substrate and the boats. The highest Ic of 52 A (corresponding to Jc = 1.6 MA/cm2 and a thickness of 800 nm) was observed at 77 K in self field at a composition x = 0.01-0.05 and y = -0.23 to -0.46. When the composition ratio is outside this range, the Ic value rapidly decreased. The superconducting critical current was highly dependent on the composition ratio. As the composition ratio is farther away from that of the highest Ic, the SmBCO (1 0 3) peak intensity increased and the amount of a-axis oriented parts increased. A dense microstructure with round-shape grains was observed in the region showing the highest Ic. The optimum composition ratio can be found by analyzing films deposited with variable deposition rates of each depositing element.

Characterization of MgO/Al2O3 Composite Film Prepared by DC Magnetron Sputtering and Its Secondary Electron Emission Properties

NASA Astrophysics Data System (ADS)

Wang, Feifei; Zhou, Fan; Wang, Jinshu; Liu, Wei; Zhang, Quan; Yin, Qiao

2018-07-01

Magnesium oxide (MgO) and MgO/Al2O3 composite thin films were prepared on silver substrates by DC magnetron sputtering technique and their secondary electron yields ( δ) and working durability under constant electron bombardment were investigated. X-ray photoelectron spectroscopy and Auger electron spectroscopy analyses reveal that uniform MgO/Al2O3 composite films were developed and residual Al exists in the films after sputtering of the Mg-Al alloy in an Ar-O2 mixed atmosphere on silver substrates heated at 400°C. The MgO/Al2O3 composite films show superior δ as high as 11.6 and much better resistance to electron bombardment than that of pure MgO films. Good secondary electron emission (SEE) properties of the MgO/Al2O3 film are probably due to the presence of alumina in the film, which has higher bond dissociation energy than MgO, as well as the presence of residual Al in the film, which contributes to effective electron transport in the film and diminished surface charging during SEE. With superior SEE performance, MgO/Al2O3 films have potential for practical electron multipliers in various vacuum electron devices.

The application of electrospun titania nanofibers in dye-sensitized solar cells.

PubMed

Krysova, Hana; Zukal, Arnost; Trckova-Barakova, Jana; Chandiran, Aravind Kumar; Nazeeruddin, Mohammad Khaja; Grätzel, Michael; Kavan, Ladislav

2013-01-01

Titania nanofibers were fabricated using the industrial Nanospider(TM) technology. The preparative protocol was optimized by screening various precursor materials to get pure anatase nanofibers. Composite films were prepared by mixing a commercial paste of nanocrystalline anatase particles with the electrospun nanofibers, which were shortened by milling. The composite films were sensitized by Ru-bipyridine dye (coded C106) and the solar conversion efficiency was tested in a dye-sensitized solar cell filled with iodide-based electrolyte solution (coded Z960). The solar conversion efficiency of a solar cell with the optimized composite electrode (η = 7.53% at AM 1.5 irradiation) outperforms that of a solar cell with pure nanoparticle film (η = 5.44%). Still larger improvement was found for lower light intensities. At 10% sun illumination, the best composite electrode showed η = 7.04%, referenced to that of pure nanoparticle film (η = 4.69%). There are non-monotonic relations between the film's surface area, dye sorption capacity and solar performance of nanofiber-containing composite films, but the beneficial effect of the nanofiber morphology for enhancement of the solar efficiency has been demonstrated.

Characterization and mechanical properties investigation of TiN-Ag films onto Ti-6Al-4V

NASA Astrophysics Data System (ADS)

Du, Dongxing; Liu, Daoxin; Zhang, Xiaohua; Tang, Jingang; Xiang, Dinggen

2016-03-01

To investigate their effect on fretting fatigue (FF) resistance of a Ti-6Al-4V alloy, hard solid lubricating composite films of TiN with varying silver contents (TiN-Ag) were deposited on a Ti-6Al-4V alloy using ion-assisted magnetron sputtering. The surface morphology and structure were analyzed by atomic force microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, and transmission electron microscopy. The hardness, bonding strength, and toughness of films were tested using a micro-hardness tester, scratch tester, and a repeated press-press test system that was manufactured in-house, respectively. The FF resistance of TiN-Ag composite films was studied using self-developed devices. The results show that the FF resistance of a titanium alloy can be improved by TiN-Ag composite films, which were fabricated using hard TiN coating doped with soft Ag. The FF life of Ag0.5, Ag2, Ag5, Ag10 and Ag20 composite films is 2.41, 3.18, 3.20, 2.94 and 2.87 times as great as that of the titanium alloy, respectively. This is because the composite films have the better toughness, friction lubrication, and high bonding strength. When the atomic fraction of Ag changes from 2% to 5%, the FF resistance of the composite films shows the best performance. This is attributed to the surface integrity of the composite film is sufficiently fine to prevent the initiation and early propagation of FF cracks.

Design of plasmonic Ag-TiO2/H3PW12O40 composite film with enhanced sunlight photocatalytic activity towards o-chlorophenol degradation.

PubMed

Lu, Nan; Wang, Yaqi; Ning, Shiqi; Zhao, Wenjing; Qian, Min; Ma, Ying; Wang, Jia; Fan, Lingyun; Guan, Jiunian; Yuan, Xing

2017-12-11

A series of plasmonic Ag-TiO 2 /H 3 PW 12 O 40 composite films were fabricated and immobilized by validated preparation technique. The chemical composition and phase, optical, SPR effect and pore-structure properties together with the morphology of as-prepared composite film are well-characterized. The multi-synergies of as-prepared composite films were gained by combined action of electron-capture action via H 3 PW 12 O 40 , visible-response induced by Ag, and Schottky-junction formed between TiO 2 -Ag. Under simulated sunlight, the maximal K app of o-chlorophenol (o-CP) reached 0.0075 min -1 which was 3.95-fold larger than that of TiO 2 film, while it was restrained obviously under acid condition. In the photocatalytic degradation process, ·OH and ·O 2 - attacked preferentially ortho and para position of o-CP molecule, and accordingly the specific degradation pathways were speculated. The novel composite film exhibited an excellent applicability due to self-regeneration of H 3 PW 12 O 40 , well-protection of metal Ag° and favorable immobilization.

Design of smart optical sensor using polyvinyl alcohol/Fluorescein sodium salt: Laser filters and optical limiting effect

NASA Astrophysics Data System (ADS)

Yahia, I. S.; Bouzidi, A.; Zahran, H. Y.; Jilani, W.; AlFaify, S.; Algarni, H.; Guermazi, H.

2018-03-01

Pure poly (vinyl alcohol) (PVA) and PVA doped Fluorescein-Sodium salt (FSS/PVA composite films) have synthesized on wide scale laser optical filters. The investigated polymeric composite films have been characterized using several methods. The XRD patterns exhibit a decrease of the average crystalline size and an increase of the internal strain, which explained the imperfection and distortion in the prepared films. The optical characterizations showed a decrease in the transmission of the incident light for different samples, which may be explained to the layer formed by intermolecular hydrogen bonding between the PVA matrix and the FSS particles. The FSS/PVA polymeric composite films are being a completely blocking in the UV-Vis light at the range between 190 and 560 nm, agreement with the optical limiting effect, which makes the composite films suitable for CUT-OFF laser filters applications. The decrease in its, directly and indirectly, allowed transition band gaps were controlled by the added FSS dyes molecules. The variation of the exponent frequency (s) of the power law for FSS/PVA polymeric composite films has been characterized to improve the hopping conduction mechanism in the materials. The dielectric permittivity (e‧) and dielectric loss (e'') have been decreased with increasing the applied frequency, and the incorporated FSS molecules due to the DC electric conductivity can cause the decreases of the polarization of the as-prepared films over the studied ranges.

New intelligent multifunctional SiO2/VO2 composite films with enhanced infrared light regulation performance, solar modulation capability, and superhydrophobicity.

PubMed

Wang, Chao; Zhao, Li; Liang, Zihui; Dong, Binghai; Wan, Li; Wang, Shimin

2017-01-01

Highly transparent, energy-saving, and superhydrophobic nanostructured SiO 2 /VO 2 composite films have been fabricated using a sol-gel method. These composite films are composed of an underlying infrared (IR)-regulating VO 2 layer and a top protective layer that consists of SiO 2 nanoparticles. Experimental results showed that the composite structure could enhance the IR light regulation performance, solar modulation capability, and hydrophobicity of the pristine VO 2 layer. The transmittance of the composite films in visible region ( T lum ) was higher than 60%, which was sufficient to meet the requirements of glass lighting. Compared with pristine VO 2 films and tungsten-doped VO 2 film, the near IR control capability of the composite films was enhanced by 13.9% and 22.1%, respectively, whereas their solar modulation capability was enhanced by 10.9% and 22.9%, respectively. The water contact angles of the SiO 2 /VO 2 composite films were over 150°, indicating superhydrophobicity. The transparent superhydrophobic surface exhibited a high stability toward illumination as all the films retained their initial superhydrophobicity even after exposure to 365 nm light with an intensity of 160 mW . cm -2 for 10 h. In addition, the films possessed anti-oxidation and anti-acid properties. These characteristics are highly advantageous for intelligent windows or solar cell applications, given that they can provide surfaces with anti-fogging, rainproofing, and self-cleaning effects. Our technique offers a simple and low-cost solution to the development of stable and visible light transparent superhydrophobic surfaces for industrial applications.

New intelligent multifunctional SiO2/VO2 composite films with enhanced infrared light regulation performance, solar modulation capability, and superhydrophobicity

PubMed Central

Wang, Chao; Zhao, Li; Liang, Zihui; Dong, Binghai; Wan, Li; Wang, Shimin

2017-01-01

Abstract Highly transparent, energy-saving, and superhydrophobic nanostructured SiO2/VO2 composite films have been fabricated using a sol–gel method. These composite films are composed of an underlying infrared (IR)-regulating VO2 layer and a top protective layer that consists of SiO2 nanoparticles. Experimental results showed that the composite structure could enhance the IR light regulation performance, solar modulation capability, and hydrophobicity of the pristine VO2 layer. The transmittance of the composite films in visible region (T lum) was higher than 60%, which was sufficient to meet the requirements of glass lighting. Compared with pristine VO2 films and tungsten-doped VO2 film, the near IR control capability of the composite films was enhanced by 13.9% and 22.1%, respectively, whereas their solar modulation capability was enhanced by 10.9% and 22.9%, respectively. The water contact angles of the SiO2/VO2 composite films were over 150°, indicating superhydrophobicity. The transparent superhydrophobic surface exhibited a high stability toward illumination as all the films retained their initial superhydrophobicity even after exposure to 365 nm light with an intensity of 160 mW.cm−2 for 10 h. In addition, the films possessed anti-oxidation and anti-acid properties. These characteristics are highly advantageous for intelligent windows or solar cell applications, given that they can provide surfaces with anti-fogging, rainproofing, and self-cleaning effects. Our technique offers a simple and low-cost solution to the development of stable and visible light transparent superhydrophobic surfaces for industrial applications. PMID:28970866

Effect of composition and strain on the electrical properties of LaNiO3 thin films

NASA Astrophysics Data System (ADS)

Zhu, Mingwei; Komissinskiy, Philipp; Radetinac, Aldin; Vafaee, Mehran; Wang, Zhanjie; Alff, Lambert

2013-09-01

The Ni content of LaNi1-xO3 epitaxial thin films grown by pulsed laser deposition has been varied by ablation from targets with different composition. While tensile strain and Ni substoichiometry reduce the conductivity, nearly stoichiometric and unstrained films show reproducibly resistivities below 100 μΩ × cm. Since the thermodynamic instability of the Ni3+ state drives defect formation, Ni defect engineering is the key to obtain highly conducting LaNiO3 thin films.

Improvement of the Heat Resistance of Prussian Blue Nanoparticles in a Clay Film Composed of Smectite Clay and ε-Caprolactam.

PubMed

Ono, Kenta; Nakamura, Takashi; Ebina, Takeo; Ishizaki, Manabu; Kurihara, Masato

2018-06-04

Prussian blue (PB) is limited in its application by its breakdown at elevated temperatures. To improve the heat resistance of PB, we prepared a composite film comprising PB nanoparticles (NPs), smectite clay, and an organic compound. The composite film had a microstructure in which PB NPs were intercalated between smectite/organic compound layers. The predominant oxidation temperature of the PB NPs in the composite film was around 500 °C in air, higher than the oxidation temperature of bulk PB in air (250 °C). This improvement in the oxidation temperature may be due to the composite film acting as a barrier to oxygen gas. These results indicate the effectiveness of clay materials for the improvement of heat resistance for low-temperature decomposition compounds, not only PB but also other porous coordination polymers.

Cassava/sugar palm fiber reinforced cassava starch hybrid composites: Physical, thermal and structural properties.

PubMed

Edhirej, Ahmed; Sapuan, S M; Jawaid, Mohammad; Zahari, Nur Ismarrubie

2017-08-01

A hybrid composite was prepared from cassava bagasse (CB) and sugar palm fiber (SPF) using casting technique with cassava starch (CS) as matrix and fructose as a plasticizer. Different loadings of SPF (2, 4, 6 and 8% w/w of dry starch) were added to the CS/CB composite film containing 6% CB. The addition of SPF significantly influenced the physical properties. It increased the thickness while decreasing the density, water content, water solubility and water absorption. However, no significant effect was noticed on the thermal properties of the hybrid composite film. The incorporation of SPF increased the relative crystallinity up to 47%, compared to 32% of the CS film. SEM micrographs indicated that the filler was incorporated in the matrix. The film with a higher concentration of SPF (CS-CB/SPF8) showed a more heterogeneous surface. It could be concluded that the incorporation of SPF led to changes in cassava starch film properties, potentially affecting the film performances. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of slurry composition on the chemical mechanical polishing of thin diamond films

PubMed Central

Werrell, Jessica M.; Mandal, Soumen; Thomas, Evan L. H.; Brousseau, Emmanuel B.; Lewis, Ryan; Borri, Paola; Davies, Philip R.; Williams, Oliver A.

2017-01-01

Nanocrystalline diamond (NCD) thin films grown by chemical vapour deposition have an intrinsic surface roughness, which hinders the development and performance of the films’ various applications. Traditional methods of diamond polishing are not effective on NCD thin films. Films either shatter due to the combination of wafer bow and high mechanical pressures or produce uneven surfaces, which has led to the adaptation of the chemical mechanical polishing (CMP) technique for NCD films. This process is poorly understood and in need of optimisation. To compare the effect of slurry composition and pH upon polishing rates, a series of NCD thin films have been polished for three hours using a Logitech Ltd. Tribo CMP System in conjunction with a polyester/polyurethane polishing cloth and six different slurries. The reduction in surface roughness was measured hourly using an atomic force microscope. The final surface chemistry was examined using X-ray photoelectron spectroscopy and a scanning electron microscope. It was found that of all the various properties of the slurries, including pH and composition, the particle size was the determining factor for the polishing rate. The smaller particles polishing at a greater rate than the larger ones. PMID:29057022

Effect of Cu2O morphology on photocatalytic hydrogen generation and chemical stability of TiO2/Cu2O composite.

PubMed

Zhu, Lihong; Zhang, Junying; Chen, Ziyu; Liu, Kejia; Gao, Hong

2013-07-01

Improving photocatalytic activity and stability of TiO2/Cu2O composite is a challenge in generating hydrogen from water. In this paper, the TiO2 film/Cu2O microgrid composite was prepared via a microsphere lithography technique, which possesses a remarkable performance of producing H2 under UV-vis light irradiation, in comparison with pure TiO2 film, Cu2O film and TiO2 film/Cu2O film. More interesting is that in TiO2 film/Cu2O microgrid, photo-corrosion of Cu2O can be retarded. After deposition of Pt on its surface, the photocatalytic activity of TiO2/Cu2O microgrid in producing H2 is improved greatly.

Microstructure and dielectric properties of cellulose acetate-ZnO/ITO composite films based on water hyacinth

NASA Astrophysics Data System (ADS)

Diantoro, M.; Mustikasari, A. A.; Wijayanti, N.; Yogihati, C.; Taufiq, A.

2017-05-01

The electrical properties of Cellulose Acetate (CA), especially extracted from water hyacinth, is rarely informed. CA is generally more stable compared to its cellulose. It has a good potential for electronic application with specific modifications such as inducing metal oxide. A combination of intrinsic properties of Zinc Oxide (ZnO) and CA is expected as a great potential for electrical and optical applications. CA-ZnO/ITO composite film was investigated in relation with its structure, dielectric constant, and the effect of light intensity on their dielectric constant. CA-ZnO composite films were prepared with different mass of ZnO i.e. 0; 0,02; 0,04; 0,06 and 0,08 grams. CA-ZnO solution was synthesized via the mixing method with PEG:DMF solvents by using a magnetic hotplate stirrer with the rotation rate of 1500 rpm at 80°C. The CA-ZnO solution was then deposited onto ITO/glass substrate by using spin coating technique. The CA-ZnO/ITO films were annealed at 160°C to remove the remaining solvents. The effects of ZnO composition on the structure (crystallinity and morphology) and dielectric constant properties were investigated by using X-Ray Diffractometer, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and LCR meter. It was shown that cellulose can be isolated from water hyacinth with the yield of 67,72 % by Chesson method and can further be transformed into CA. The X-ray diffraction pattern showed that there are 2 phases formed i.e. CA and ZnO. Furthermore, greater ZnO amount increased the crystallinity of composite films. The CA-ZnO films exhibit porous films with ZnO distributed on the CA surface films. Therefore, ZnO increases the dielectric constant of CA-ZnO composite films.

Effect of Tunable Surface Potential on the Structure of Spin-Cast Polymeric Blend Films

NASA Astrophysics Data System (ADS)

Hawker, C.; Huang, E.; Russell, T. P.

1998-03-01

The demixing of binary polymeric mixtures has been studied with various surface potentials. This was performed by spin casting polystyrene/poly(methyl methacrylate) mixtures on to silicon substrates that had been modified with an end-grafted random copolymer brush layer. The composition of the random copolymer brush, containing the same monomeric components as the homopolymers can be varied in a precise manner over the entire concentration range. Atomic force and optical microscopy were used to study the morphology formed during spin casting and after annealing. Further insight into the structure was gained by rinsing these films with preferential solvents to remove one of the constituents and by performing the microscopy measurements. Finally, x-ray photoelectron spectroscopy, XPS, was used to elucidate the composition of the film near the air/polymer interface. Our data show that the resulting thin film structure depends strongly on the composition of the end grafted random copolymer film. Furthermore, the effect of thickness, solvent used in casting, and annealing conditions will be addressed.

Cellulose-glycerol-polyvinyl alcohol composite films for food packaging: Evaluation of water adsorption, mechanical properties, light-barrier properties and transparency.

PubMed

Cazón, Patricia; Vázquez, Manuel; Velazquez, Gonzalo

2018-09-01

Nowadays consumers are aware of environmental problems. As an alternative to petrochemical polymers for food packaging, researchers have been focused on biopolymeric materials as raw material. The aim of this study was to evaluate mechanical properties (toughness, burst strength and distance to burst), water adsorption, light-barrier properties and transparency of composite films based on cellulose, glycerol and polyvinyl alcohol. Scanning electron microscopy, spectral analysis (FT-IR and UV-VIS-NIR) and differential scanning calorimetry were performed to explain the morphology, structural and thermal properties of the films. Results showed that polyvinyl alcohol enhances the toughness of films up to 44.30 MJ/m 3 . However, toughness decreases when glycerol concentration is increased (from 23.41 to 10.55 MJ/m 3 ). Water adsorption increased with increasing polyvinyl alcohol concentration up to 222%. Polyvinyl alcohol increased the film thickness. The films showed higher burst strength (up to 12014 g) than other biodegradable films. The films obtained have optimal values of transparency like those values of synthetic polymers. Glycerol produced a UV protective effect in the films, an important effect for food packaging to prevent lipid oxidative deterioration. Results showed that it is feasible to obtain cellulose-glycerol-polyvinyl alcohol composite films with improved properties. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effects of hydrogenation on thermal conductivity of ultrananocrystalline diamond/amorphous carbon composite films prepared via coaxial arc plasma deposition

NASA Astrophysics Data System (ADS)

Takeichi, Satoshi; Nishiyama, Takashi; Tabara, Mitsuru; Kawawaki, Shuichi; Kohno, Masamichi; Takahashi, Koji; Yoshitake, Tsuyoshi

2018-06-01

Ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite (UNCD/a-C:H) and UNCD/non-hydrogenated amorphous carbon (a-C) composite (UNCD/a-C) films were prepared via coaxial arc plasma deposition, and their thermal conductivity and interfacial conductance in grain boundaries were measured using a time-domain thermoreflectance method. The interfacial conductance was estimated to be 1,010 and 4,892 MW/(m2·K) for UNCD/a-C:H and UNCD/a-C films, respectively. The reasons for the hydrogenated film having lower interfacial conductance than the non-hydrogenated film are 1) the reduced number of carriers that contribute to heat transport and 2) the hydrogen atoms, which are preferentially located at the grain boundaries and enhance phonon scattering.

Preparation of Chitin-PLA laminated composite for implantable application.

PubMed

Nasrin, Romana; Biswas, Shanta; Rashid, Taslim Ur; Afrin, Sanjida; Jahan, Rumana Akhter; Haque, Papia; Rahman, Mohammed Mizanur

2017-12-01

The present study explores the possibilities of using locally available inexpensive waste prawn shell derived chitin reinforced and bioabsorbable polylactic acid (PLA) laminated composites to develop new materials with excellent mechanical and thermal properties for implantable application such as in bone or dental implant. Chitin at different concentration (1-20% of PLA) reinforced PLA films (CTP) were fabricated by solvent casting process and laminated chitin-PLA composites (LCTP) were prepared by laminating PLA film (obtained by hot press method) with CTP also by hot press method at 160 °C. The effect of variation of chitin concentration on the resulting laminated composite's behavior was investigated. The detailed physico-mechanical, surface morphology and thermal were assessed with different characterization technique such as FT-IR, XRD, SEM and TGA. The FTIR spectra showed the characteristic peaks for chitin and PLA in the composites. SEM images showed an excellent dispersion of chitin in the films and composites. Thermogravimetric analysis (TGA) showed that the complete degradation of chitin, PLA film, 5% chitin reinforced PLA film (CTP2) and LCTP are 98%, 95%, 87% and 98% respectively at temperature of 500 °C. The tensile strength of the LCTP was found 25.09 MPa which is significantly higher than pure PLA film (18.55 MPa) and CTP2 film (8.83 MPa). After lamination of pure PLA and CTP2 film, the composite (LCTP) yielded 0.265-1.061% water absorption from 30 min to 24 h immerse in water that is much lower than PLA and CTP. The increased mechanical properties of the laminated films with the increase of chitin content indicated good dispersion of chitin into PLA and strong interfacial actions between the polymer and chitin. The improvement of mechanical properties and the results of antimicrobial and cytotoxicity of the composites also evaluated and revealed the composite would be a suitable candidate for implant application in biomedical sector.

Preparation of reduced graphene oxide/gelatin composite films with reinforced mechanical strength

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Wenchao; Wang, Zhipeng; School of Chemical Engineering, Tianjin University, Tianjin

2012-09-15

Highlights: ► We used and compared different proportion of gelatin and chitosan as reducing agents. ► The mechanical properties of the films are investigated, especially the wet films. ► The cell toxicity of the composite films as biomaterial is carried out. ► The water absorption capabilities of the composite films also studied. -- Abstract: Graphene oxide (GO) was reduced by chitosan/gelatin solution and added to gelatin (Gel) to fabricate reduced graphene oxide/gelatin (RGO/Gel) films by a solvent-casting method using genipin as cross-linking agent. The structure and properties of the films were characterized by scanning electron microscopy (SEM), X-ray powder diffractionmore » (XRD), thermogravimetric analysis (TGA) and UV–vis spectroscopy. The addition of RGO increased the tensile strength of the RGO/Gel films in both dry and wet states, but decreased their elongation at break. The incorperation of RGO also decreased the swelling ability of the films in water. Cell cultures were carried out in order to test the cytotoxicity of the films. The cells grew and reproduced well on the RGO/Gel films, indicating that the addition of RGO has no negative effect on the compatibility of the gelatin. Therefore, the reduced graphene oxide/gelatin composite is a promising biomaterial with excellent mechanical properties and good cell compatibility.« less

Biodegradation of poly(hydroxy butanoic acid) copolymer mulch films in soil

NASA Astrophysics Data System (ADS)

Kukade, Pranav

Agricultural mulch films that are used to cover soil of crop rows contribute to earlier maturation of crops and higher yield. Incineration and landfill disposals are the most common means of disposal of the incumbent polyethylene (PE) mulch films; however, these are not environment friendly options. Biodegradable mulch films that can be rototilled into the soil after crop harvest are a promising alternative to offset problems such as landfill disposal, film retrieval and disposal costs. In this study, an in-house laboratory scale test method was developed in which the rate of disintegration, as a result of biodegradation of films based on polyhydroxybutanoic acid (PHB) copolymers was investigated in a soil environment using the residual weight loss method. The influence of soil composition, moisture levels in the soil, and industry-standard anti-microbial additive in the film composition on the rate of disintegration of PHB copolymer films was investigated. The soil composition has significant effect on the disintegration kinetics of PHB copolymer films, since the increasing compost levels in the soil lowered the rate of disintegration of the film. Also, with the increase in moisture level up to a threshold limit, the microbial activity and, hence, the rate of disintegration increased. Lastly, the developed lab-scale test protocol was found to be sensitive to even small concentrations of industry-standard antimicrobial additive in the film composition.

Effects of Polypropylene Orientation on Mechanical and Heat Seal Properties of Polymer-Aluminum-Polymer Composite Films for Pouch Lithium-Ion Batteries

PubMed Central

Chen, Jinyao; Yang, Feng; Kang, Jian; Cao, Ya; Xiang, Ming

2018-01-01

In this study, polyamide-aluminum foil-polypropylene (PA-Al-PP) composite films with different orientation status of the PP layer were prepared, and their morphology, tensile, peeling and heat seal behavior were studied. The comparative study of tensile and fracture behaviors of single-layer film of PA, Al and PP, as well as the composite films of PA-Al, PP-Al and PA-Al-PP revealed that in PA-Al-PP composite film, the PA layer with the highest tensile strength can share the tensile stress from the Al layer during stretching, while the PP layer with the lowest tensile strength can prevent further development of the small cracks on boundary of the Al layer during stretching. Moreover, the study of heat seal behavior suggested that both the orientation status and the heat seal conditions were important factors in determining the heat seal strength (HSS) and failure behavior of the sample. Four failure types were observed, and a clear correspondence between HSS and failure types was found. The results also elucidated that for the composite film, only in the cases where the tensile stress was efficiently released by each layer during HSS measurement could the composite film exhibit desired high HSS that was even higher than its tensile strength. PMID:29337881

Effect of laser processing on physical properties of (Ba0.85Ca0.15Ti0.9Zr0.1O3) lead-free thick films fabricated by the electrophoretic deposition

NASA Astrophysics Data System (ADS)

Ramana, E. Venkata; Ferreira, N. M.; Mahajan, A.; Ferro, Marta C.; Figueiras, F.; Graça, M. P. F.; Valente, M. A.

2018-02-01

In this work, we have fabricated lead-free piezoelectric Ba0.85Ca0.15Ti0.9Zr0.1O3 thick films by the electrophoretic deposition (EPD) followed by a continuous-wave CO2 laser annealing and demonstrated the effect of laser energy on the quality of the final product. Thick films annealed under optimized conditions, 50 W/15 min, show a controlled microstructure/density compared to those derived from higher laser power/annealing time/conventional sintering. The increase in laser power above this limit affects the grain growth kinetics and results in the compositional heterogeneities. From the results of Raman spectra, it was found that the film annealed under optimized conditions has a high degree of crystallinity and tetragonality, while the increase in laser fluence results in the growth of A1g mode. The controlled composition and microstructure, thus has resulted in the improved ferroelectricity with a remanent polarization 12 μC/cm2, on par with the bulk or larger than the films grown by the chemical solution deposition techniques. From the piezoresponse studies, we found that the film annealed at 75 W/5 min has weak ferroelectric nature with no switchable ferroelectric domains compared to those under optimized conditions. Subtle differences in phase transition temperatures and drop in ferroelectric polarization, for films annealed conventionally or at higher laser fluence, are related to porosity or site defects as well as compositional heterogeneities. Our study demonstrates that the combination of EPD and laser annealing is an effective way to achieve high quality piezoelectric thick films with a controlled composition, useful for energy harvesting applications.

Physicochemical properties of marine collagen-alginate biomaterial

NASA Astrophysics Data System (ADS)

Soon, K. S.; Hii, S. L.; Wong, C. L.; Leong, L. K.; Woo, K. K.

2017-12-01

Collagen base biomaterials are widely applied in the field of tissue engineering. However, these fibrous proteins in animal connective tissues are insufficient to fulfill the mechanical properties for such applications. Therefore, alginate as a natural polysaccharide was incorporated. In this study, Smooth wolf herring skins was collected from the local fish ball processing industry for collagen extraction using acid solubilisation method. On the other hand, alginate from brown seaweed (Sargassum polycystum) was extracted with calcium carbonate at 50 °C. The composite films of different collagen and alginate ratio were prepared by lyophilisation with pure collagen film as control. The effects of alginate on swelling behaviour, porosity, collagenase degradation and tensile strength of the composite films were investigated. Swelling behaviour increased with alginate content, 50 % alginate film achieved 1254.75 % swelling after 24 h. All composite films achieved more than 80 % porosity except the film with 80 % collagen (65.41 %). Porosity was highest in 100 % alginate (94.30 %). Highest tensile strength (1585.87 kPa) and young modulus (27.05 MPa) was found in 50 % alginate film. In addition, resistance to collagenase degradation was improved with alginate content, lowest degradation rate was determined in 80 % alginate film. Results indicated alginate is efficient in improving some mechanical properties of the composite film.

Development of Biopolymer Composite Films Using a Microfluidization Technique for Carboxymethylcellulose and Apple Skin Particles

PubMed Central

Choi, Inyoung; Chang, Yoonjee; Shin, So-Hyang; Joo, Eunmi; Song, Hyun Ju; Eom, Haeyoung; Han, Jaejoon

2017-01-01

Biopolymer films based on apple skin powder (ASP) and carboxymethylcellulose (CMC) were developed with the addition of apple skin extract (ASE) and tartaric acid (TA). ASP/CMC composite films were prepared by mixing CMC with ASP solution using a microfluidization technique to reduce particle size. Then, various concentrations of ASE and TA were incorporated into the film solution as an antioxidant and an antimicrobial agent, respectively. Fourier transform infrared (FTIR), optical, mechanical, water barrier, and solubility properties of the developed films were then evaluated to determine the effects of ASE and TA on physicochemical properties. The films were also analyzed for antioxidant effect on 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and antimicrobial activities against Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica, and Shigella flexneri. From the results, the ASP/CMC film containing ASE and TA was revealed to enhance the mechanical, water barrier, and solubility properties. Moreover, it showed the additional antioxidant and antimicrobial properties for application as an active packaging film. PMID:28617325

Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of ultrathin block copolymer films.

PubMed

Huang, Changchun; Wen, Gangyao; Li, Jingdan; Wu, Tao; Wang, Lina; Xue, Feifei; Li, Hongfei; Shi, Tongfei

2016-09-15

Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of spin-coated polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films (<20nm thick) were mainly investigated by atomic force microscopy. Surface chemical analysis of the ultrathin films annealed for different times were performed using X-ray photoelectron spectroscopy and contact angle measurement. With the annealing of acetone vapor, dewetting of the films with different thicknesses occur via the spinodal dewetting and the nucleation and growth mechanisms, respectively. The PS-b-PMMA films rupture into droplets which first coalesce into large ones to reduce the surface free energy. Then the large droplets rupture into small ones to increase the contact area between PMMA blocks and acetone molecules resulting from ultimate migration of PMMA blocks to droplet surface, which is a novel dewetting process observed in spin-coated films for the first time. Copyright © 2016 Elsevier Inc. All rights reserved.

Two-component spin-coated Ag/CNT composite films based on a silver heterogeneous nucleation mechanism adhesion-enhanced by mechanical interlocking and chemical grafting.

PubMed

Zhang, Yang; Kang, Zhixin; Bessho, Takeshi

2017-03-10

In this paper, a new method for the synthesis of silver carbon nanotube (Ag/CNT) composite films as conductive connection units for flexible electronic devices is presented. This method is about a two-component solution process by spin coating with an after-treatment annealing process. In this method, multi-walled carbon nanotubes (MWCNTs) act as the core of silver heterogeneous nucleation, which can be observed and analyzed by a field-emission scanning electron microscope. With the effects of mechanical interlocking, chemical grafting, and annealing, the interfacial adhesive strength between films and PET sheets was enhanced to 12 N cm -1 . The tensile strength of the Ag/CNT composite films was observed to increase by 38% by adding 5 g l -1 MWCNTs. In the four-probe method, the resistivity of Ag/CNT-5 declined by 78.2% compared with pristine Ag films. The anti-fatigue performance of the Ag/CNT composite films was monitored by cyclic bending deformation and the results revealed that the growth rate of electrical resistance during the deformation was obviously retarded. As for industrial application, this method provides an efficient low-cost way to prepare Ag/CNT composite films and can be further applied to other coating systems.

Fabrication and notable optical nonlinearities of ultrathin composite films derived from water-soluble Keggin-type polyoxometalates and water-insoluble phthalocyanine.

PubMed

Shehzad, Farooq Khurum; Qu, Ningning; Zhou, Yunshan; Zhang, Lijuan; Ji, Huanyao; Shi, Zonghai; Li, Jiaqi; Hassan, Sadaf Ul

2016-11-28

Composite films with the general formula (POM/CuTAPc) n derived from water-soluble Keggin-type polyoxometalates (POMs = H 5 PMo 10 V 2 O 40 , H 4 SiW 12 O 40 , H 3 PMo 12 O 40 and H 3 PW 12 O 40 ) and water-insoluble 4,9,16,23-copper tetraaminophthalocyanine (denoted CuTAPc) are successfully fabricated by a layer-by-layer self-assembly technique and systematically characterized. The structure of the polyoxometalate anions in the multilayers is kept intact; the deposition amounts of POM and CuTAPc remain constant in every adsorption cycle of the composite film assembly process. The nonlinear optical properties of the composite films were studied by a Z-scan technique at a wavelength of 532 nm and a pulse width of 7 ns. The results not only show that the composite films exhibit notable optical nonlinear self-defocusing behavior and a saturated absorption effect with the nonlinear optical absorption co-efficient β, refractive index n 2 , and third-order NLO susceptibility χ (3) of the films increasing with the increase in number of layers of the films, but also reveal importantly that the discrepancy of LUMO levels between CuTAPc and POMs is proportional to their third-order NLO response.

Influence of 20 MeV electron irradiation on the optical properties and phase composition of SiOx thin films

NASA Astrophysics Data System (ADS)

Hristova-Vasileva, Temenuga; Petrik, Peter; Nesheva, Diana; Fogarassy, Zsolt; Lábár, János; Kaschieva, Sonia; Dmitriev, Sergei N.; Antonova, Krassimira

2018-05-01

Homogeneous films from SiO1.3 (250 nm thick) were deposited on crystalline Si substrates by thermal evaporation of silicon monoxide. A part of the films was further annealed at 700 °C to grow amorphous Si (a-Si) nanoclusters in an oxide matrix, thus producing composite a-Si-SiO1.8 films. Homogeneous as well as composite films were irradiated by 20-MeV electrons at fluences of 7.2 × 1014 and 1.44 × 1015 el/cm2. The film thicknesses and optical constants were explored by spectroscopic ellipsometry. The development of the phase composition of the films caused by the electron-beam irradiation was studied by transmission electron microscopy. The ellipsometric and electron microscopy results have shown that the SiOx films are optically homogeneous and the electron irradiation with a fluence of 7.2 × 1014 el/cm2 has led to small changes in the optical constants and the formation of very small a-Si nanoclusters. The irradiation of the a-Si-SiOx composite films caused a decrease in the effective refractive index and, at the same time, an increase in the refractive index of the oxide matrix. Irradiation induced increase in the optical band gap and decrease in the absorption coefficient of the thermally grown amorphous Si nanoclusters have also been observed. The obtained results are discussed in terms of the formation of small amorphous silicon nanoclusters in the homogeneous layers and electron irradiation induced reduction in the nanocluster size in the composite films. The conclusion for the nanoparticle size reduction is supported by infrared transmittance results.

One-Step Synthesis of Silver Nanoparticles on Polydopamine-Coated Sericin/Polyvinyl Alcohol Composite Films for Potential Antimicrobial Applications.

PubMed

Cai, Rui; Tao, Gang; He, Huawei; Song, Kai; Zuo, Hua; Jiang, Wenchao; Wang, Yejing

2017-04-30

Silk sericin has great potential as a biomaterial for biomedical applications due to its good hydrophilicity, reactivity, and biodegradability. To develop multifunctional sericin materials for potential antibacterial application, a one-step synthesis method for preparing silver nanoparticles (AgNPs) modified on polydopamine-coated sericin/polyvinyl alcohol (PVA) composite films was developed. Polydopamine (PDA) acted as both metal ion chelating and reducing agent to synthesize AgNPs in situ on the sericin/PVA composite film. Scanning electron microscopy and energy dispersive spectroscopy analysis revealed that polydopamine could effectively facilitate the high-density growth of AgNPs as a 3-D matrix. X-ray diffractometry studies suggested the synthesized AgNPs formed good face-centered cubic crystalline structures. Contact angle measurement and mechanical test indicated AgNPs modified PDA-sericin/PVA composite film had good hydrophilicity and mechanical property. The bacterial growth curve and inhibition zone assays showed the AgNPs modified PDA-sericin/PVA composite film had long-term antibacterial activities. This work develops a new method for the preparation of AgNPs modified PDA-sericin/PVA film with good hydrophilicity, mechanical performance and antibacterial activities for the potential antimicrobial application in biomedicine.

Controlled release of tocopherols from polymer blend films

NASA Astrophysics Data System (ADS)

Obinata, Noe

Controlled release packaging has great potential to increase storage stability of foods by releasing active compounds into foods continuously over time. However, a major limitation in development of this technology is the inability to control the release and provide rates useful for long term storage of foods. Better understanding of the factors affecting active compound release is needed to overcome this limitation. The objective of this research was to investigate the relationship between polymer composition, polymer processing method, polymer morphology, and release properties of active compounds, and to provide proof of principle that compound release is controlled by film morphology. A natural antioxidant, tocopherol was used as a model active compound because it is natural, effective, heat stable, and soluble in most packaging polymers. Polymer blend films were produced from combination of linear low density polyethylene (LLDPE) and high density polyethylene (HDPE), polypropylene (PP), or polystyrene (PS) with 3000 ppm mixed tocopherols using conventional blending method and innovative blending method, smart blending with a novel mixer using chaotic advection. Film morphologies were visualized with scanning electron microscopy (SEM). Release of tocopherols into 95% ethanol as a food simulant was measured by UV/Visible spectrophotometry or HPLC, and diffusivity of tocopherols in the polymers was estimated from this data. Polymer composition (blend proportions) and processing methods have major effects on film morphology. Four different types of morphologies, dispersed, co-continuous, fiber, and multilayer structures were developed by either conventional extrusion or smart blending. With smart blending of fixed polymer compositions, different morphologies were progressively developed with fixed polymer composition as the number of rod rotations increased, providing a way to separate effects of polymer composition and morphology. The different morphologies obtained using conventional and smart blending greatly affected tocopherol release. Strong correlation was observed between morphology and release rate: multilayer, slow release; co-continuous and fiber, moderate; disperse: fast release. Results indicate that morphology can be manipulated by polymer composition and processing method, and release rates of tocopherols are varied with polymer morphology. Manipulating polymer compositions and film morphologies may provide a means to control the release of tocopherols from food contact films.

Bioactive films of zein/magnetite magnetically stimuli-responsive for controlled drug release

NASA Astrophysics Data System (ADS)

Marín, Tíffany; Montoya, Paula; Arnache, Oscar; Pinal, Rodolfo; Calderón, Jorge

2018-07-01

The Zein films in two configurations with magnetite nanoparticles (zein/NPs) and magnetite-acetaminophen (zein/NPs/Drug) were used as magnetically stimuli-responsive systems to propose a model of controlled release by dissolution and diffusion mechanism. Composite material films of zein/NPs and zein/NPs/Drug were made by dispersion of magnetite nanoparticles into zein solution then solvent casting of the solution on a flat Teflon substrate. The properties of composite films were analyzed by magnetization curves of (MvsH) and measurements of magnetic force microscopy (MFM). Drug release from the zein/NPs/Drug composite films was determined using a type II dissolution apparatus for a period of 2 h under applied magnetic field conditions. In addition, the diffusion mechanism was tested with zein/NPs films into diffusion cell containing acetaminophen solution for 24 h and using a permanent magnet as a remote trigger device. The results showed that the magnetite nanoparticles contained in the zein/NPs and zein/NPs/Drug composite films are stable, i.e., they do not undergo sufficiently high levels of oxidation as to alter their magnetic properties. Furthermore, the dissolution and diffusion results lead us to conclude that zein composite films effectively behave as stimuli-responsive systems triggered by an external magnetic field applied. The result is a model controlled release system whereby drug release can be controlled by adjusting the magnitude of the applied magnetic field.

Polycarbonate-Based Blends for Optical Non-linear Applications.

PubMed

Stanculescu, F; Stanculescu, A

2016-12-01

This paper presents some investigations on the optical and morphological properties of the polymer (matrix):monomer (inclusion) composite materials obtained from blends of bisphenol A polycarbonate and amidic monomers. For the preparation of the composite films, we have selected monomers characterised by a maleamic acid structure and synthesised them starting from maleic anhydride and aniline derivatives with -COOH, -NO2, -N(C2H5)2 functional groups attached to the benzene ring. The composite films have been deposited by spin coating using a mixture of two solutions, one containing the matrix and the other the inclusion, both components of the composite system being dissolved in the same solvent. The optical transmission and photoluminescence properties of the composite films have been investigated in correlation with the morphology of the films. The scanning electron microscopy and atomic force microscopy have revealed a non-uniform morphology characterised by the development of two distinct phases. We have also investigated the generation of some optical non-linear (ONL) phenomena in these composite systems. The composite films containing as inclusions monomers characterised by the presence of one -COOH or two -NO2 substituent groups to the aromatic nucleus have shown the most intense second-harmonic generation (SHG). The second-order optical non-linear coefficients have been evaluated for these films, and the effect of the laser power on the ONL behaviour of these materials has also been emphasised.

Polycarbonate-Based Blends for Optical Non-linear Applications

NASA Astrophysics Data System (ADS)

Stanculescu, F.; Stanculescu, A.

2016-02-01

This paper presents some investigations on the optical and morphological properties of the polymer (matrix):monomer (inclusion) composite materials obtained from blends of bisphenol A polycarbonate and amidic monomers. For the preparation of the composite films, we have selected monomers characterised by a maleamic acid structure and synthesised them starting from maleic anhydride and aniline derivatives with -COOH, -NO2, -N(C2H5)2 functional groups attached to the benzene ring. The composite films have been deposited by spin coating using a mixture of two solutions, one containing the matrix and the other the inclusion, both components of the composite system being dissolved in the same solvent. The optical transmission and photoluminescence properties of the composite films have been investigated in correlation with the morphology of the films. The scanning electron microscopy and atomic force microscopy have revealed a non-uniform morphology characterised by the development of two distinct phases. We have also investigated the generation of some optical non-linear (ONL) phenomena in these composite systems. The composite films containing as inclusions monomers characterised by the presence of one -COOH or two -NO2 substituent groups to the aromatic nucleus have shown the most intense second-harmonic generation (SHG). The second-order optical non-linear coefficients have been evaluated for these films, and the effect of the laser power on the ONL behaviour of these materials has also been emphasised.

Impact resistance performance of diamond film on a curved molybdenum substrate

NASA Astrophysics Data System (ADS)

Chen, Yang; Gou, Li

2017-08-01

Diamond films with different thicknesses were deposited on flat and curved molybdenum substrate by the microwave plasma chemical vapour deposition (MPCVD) method. Scanning electronic microscopy, atomic force microscopy and Raman spectroscopy were employed to characterise the morphology, the surface roughness and the composition of the films, respectively. A NanoTest system was used for hardness, elastic modulus and nanoimpact tests. The curved surface and ductility of the molybdenum substrate allow large deformation for the thinner films. The substrate has less effect on impact for the thicker film, the deformation of which is mainly determined by the film composition. Under a load of 50 mN and 75 cycles, less deformation occurred for the 22 μm thick film on the curved molybdenum substrate.

Calcinated tea and cellulose composite films and its dielectric and lead adsorption properties.

PubMed

Jayaramudu, Tippabattini; Varaprasad, Kokkarachedu; Kim, Hyun Chan; Kafy, Abdullahil; Kim, Jung Woong; Kim, Jaehwan

2017-09-01

In this paper, calcinated tea and cellulose composite (CTCC) films were fabricated via solution casting method. Chemical structure, morphology, crystallinity and thermal stability of the fabricated films were characterized by using Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and thermogravimetric analysis. The effect of calcinated tea loading on the properties of the prepared CTCC films was studied. The results suggest that the prepared CTCC films show higher mechanical properties, thermal stability and dielectric constant than the neat cellulose film. In addition, the CTCC films adsorb Pb 2+ ions and its adsorption performance depends on the calcinated tea content and pH level. The CTCC films are useful for sensors, flexible capacitor as well as lead adsorption applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Correlation between optical properties and chemical composition of sputter-deposited germanium oxide (GeOx) films

NASA Astrophysics Data System (ADS)

Murphy, N. R.; Grant, J. T.; Sun, L.; Jones, J. G.; Jakubiak, R.; Shutthanandan, V.; Ramana, C. V.

2014-05-01

Germanium oxide (GeOx) films were grown on (1 0 0) Si substrates by reactive Direct-Current (DC) magnetron sputter-deposition using an elemental Ge target. The effects of oxygen gas fraction, Г = O2/(Ar + O2), on the deposition rate, structure, chemical composition and optical properties of GeOx films have been investigated. The chemistry of the films exhibits an evolution from pure Ge to mixed Ge + GeO + GeO2 and then finally to GeO2 upon increasing Г from 0.00 to 1.00. Grazing incidence X-ray analysis indicates that the GeOx films grown were amorphous. The optical properties probed by spectroscopic ellipsometry indicate that the effect of Г is significant on the optical constants of the GeOx films. The measured index of refraction (n) at a wavelength (λ) of 550 nm is 4.67 for films grown without any oxygen, indicating behavior characteristic of semiconducting Ge. The transition from germanium to mixed Ge + GeO + GeO2 composition is associated with a characteristic decrease in n (λ = 550 nm) to 2.62 and occurs at Г = 0.25. Finally n drops to 1.60 for Г = 0.50-1.00, where the films become GeO2. A detailed correlation between Г, n, k and stoichiometry in DC sputtered GeOx films is presented and discussed.

Ionizing Organic Compound Based Nanocomposites for Efficient Gamma-Ray Sensor

NASA Technical Reports Server (NTRS)

Singh, N. B.; Dayal, Vishall; Su, Ching-Hua; Arnold, Bradley; Choa, Fow-Sen; Kabandana, Monia G. K.; House, David

2017-01-01

Thin film and nanocrystalline materials of oxides have been very attractive choice as low cost option for gamma-ray detection and have shown great promise. Our studies on pure oxide films indicated that thickness and microstructure have pronounced effect on sensitivity. Since the interaction of gamma-ray with composites involves all three interaction processes; photoelectric effect, Compton scattering, and pair production, composites containing ionic organics have better chance for enhancing sensitivity. In the composites of ionizing organics oxidation effect of unusual oxides changes much faster and hence increases the sensitivity of radiation. In this study, we have used nickel oxide and titanium oxide in ionic organics to develop composite materials for low energy gamma-ray sensing. We prepared composites containing ethylene carbonate and evaluated the effect of commercial Cs-137 radiation source by studying current-voltage relationship at several frequencies. Radiated samples showed higher resistivity compared to as prepared composites.

P(VDF-TrFE)/BaTiO3 Nanoparticle Composite Films Mediate Piezoelectric Stimulation and Promote Differentiation of SH-SY5Y Neuroblastoma Cells.

PubMed

Genchi, Giada Graziana; Ceseracciu, Luca; Marino, Attilio; Labardi, Massimiliano; Marras, Sergio; Pignatelli, Francesca; Bruschini, Luca; Mattoli, Virgilio; Ciofani, Gianni

2016-07-01

Poly(vinylidene fluoride-trifluoroethylene, P(VDF-TrFE)) and P(VDF-TrFE)/barium titanate nanoparticle (BTNP) films are prepared and tested as substrates for neuronal stimulation through direct piezoelectric effect. Films are characterized in terms of surface, mechanical, and piezoelectric features before in vitro testing on SH-SY5Y cells. In particular, BTNPs significantly improve piezoelectric properties of the films (4.5-fold increased d31 ). Both kinds of films support good SH-SY5Y viability and differentiation. Ultrasound (US) stimulation is proven to elicit Ca(2+) transients and to enhance differentiation in cells grown on the piezoelectric substrates. For the first time in the literature, this study demonstrates the suitability of polymer/ceramic composite films and US for neuronal stimulation through direct piezoelectric effect. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Orodispersible films: Product transfer from lab-scale to continuous manufacturing.

PubMed

Thabet, Yasmin; Breitkreutz, Joerg

2018-01-15

Orodispersible films have been described as new beneficial dosage forms for special patient populations. Due to various production settings, different requirements on film formulations are required for non- continuous and continuous manufacturing. In this study, a continuous coating machine was qualified in regards of the process conditions for film compositions and their effects on the formed films. To investigate differences between both manufacturing processes, various film formulations of hydrochlorothiazide and hydroxypropylcellulose (HPC) or hydroxypropylmethycellulose (HPMC) as film formers were produced and the resulting films were characterized. The qualification of the continuously operating coating machine reveals no uniform heat distribution during drying. Coating solutions for continuous manufacturing should provide at least a dynamic viscosity of 1 Pa*s (wet film thickness of 500 μm, velocity of 15.9 cm/min). HPC films contain higher residuals of ethanol or acetone in bench-scale than in continuous production mode. Continuous production lead to lower drug content of the films. All continuously produced films disintegrate within less than 30 s. There are observed significant effects of the production process on the film characteristics. When transferring film manufacturing from lab-scale to continuous mode, film compositions, processing conditions and suitable characterization methods have to be carefully selected and adopted. Copyright © 2017 Elsevier B.V. All rights reserved.

Processing, Characteristics, and Optical Properties of Wet Chemically Derived Planar Dielectric Waveguides.

NASA Astrophysics Data System (ADS)

Weisenbach, Lori Ann

An experimental study of the processing and attenuation characteristics of solution derived, thin film, planar waveguides was made. In this study, the densification and attenuation characteristics of a variety of compositions were compared. To insure that the effects measured reflected compositional differences and not processing artifacts, guidelines for the reproducible fabrication of optical quality layers, irrespective of composition, were established. A broad range of compositions were prepared and an effort was made to keep the various solution syntheses as simple and similar as possible. The densification and attenuation of binary SiO _2-TiO_2 compositions was measured, then compared to the densification and attenuation of SiO_2-TiO_2 -R_{rm x}O _{rm y} (where R = Al or Zn) ternary compositions. Film densification was not strongly dependent upon composition, and was successfully modelled using the Lorentz-Lorenz relation, assuming the open volume in the undensified films were filled with adsorbed water. The attenuation measured at 632.8 nm did not vary with composition, except for the Zn ternary samples. Waveguides with losses of <1dB/cm could be fabricated from all other compositions. Waveguide attenuation was measured for films of different thickness, and compared to modelled predictions. The attenuation increased as layer thickness decreased, suggesting the predominance of the surface scattering contribution. To confirm that absorption losses were negligible, the wavelength dependence of the waveguides was measured. The wavelength dependence varied with composition, suggesting the absorption varied with composition. Possible mechanisms of absorption in the waveguides were discussed; the interaction of the atmosphere with the film structure is proposed as the cause of the deterioration. Film development for the binary SiO_2 -TiO_2 films was also studied as a function of increased firing time at 500^ circC. Multiple firings at 500^ circC increased the film density and the resistance to deterioration, but also increased the surface roughness of the films. Increased surface roughness, increased the scattering losses measured for the guide. The application of solution derived thin films was demonstrated with the successful fabrication of a novel optical device. The fabrication of the Single Leakage -Channel Grating Coupler illustrated specific design tolerances could be met and the resulting device performance near the theoretical maximum.

Preparation of nanocellulose from micro-crystalline cellulose: The effect on the performance and properties of agar-based composite films.

PubMed

Shankar, Shiv; Rhim, Jong-Whan

2016-01-01

A facile approach has been performed to prepare nanocellulose (NC) from micro-crystalline cellulose (MCC) and test their effect on the performance properties of agar-based composite films. The NC was characterized by STEM, XRD, FTIR, and TGA. The NC was well dispersed in distilled water after sonication and their size was in the range of 100-500nm. The XRD results revealed the crystallinity of NC. The crystallinity index of NC (0.71) was decreased compared to the MCC (0.81). The effect of NC or MCC content (1, 3, 5 and 10wt% based on agar) on the mechanical, water vapor permeability (WVP), and thermal properties of the composites were studied. The NC obtained from MCC can be used as a reinforcing agent for the preparation of biodegradable composites films for their potential use in the development of biodegradable food packaging materials. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of polyethyleneimine modified graphene on the mechanical and water vapor barrier properties of methyl cellulose composite films.

PubMed

Liu, Hongyu; Liu, Cuiyun; Peng, Shuge; Pan, Bingli; Lu, Chang

2018-02-15

A series of novel methyl cellulose (MC) composite films were prepared using polyethyleneimine reduced graphene oxide (PEI-RGO) as an effective filler for water vapor barrier application. The as-prepared PEI-RGO/MC composites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, tensile test and scanning electron microscopy. The experimental and theoretical results exhibited that PEI-RGO was uniformly dispersed in the MC matrix without aggregation and formed an aligned dispersion. The addition of PEI-RGO resulted in an enhanced surface hydrophobicity and a tortuous diffusion pathway for water molecules. Water vapor permeability of PEI-RGO/MC with loading of 3.0% of surface modified graphene was as low as 5.98×10 -11 gmm -2 s -1 Pa -1 . The synergistic effects of enhanced surface hydrophobicity and tortuous diffusion pathway were accounted for the improved water vapor barrier performance of the PEI-RGO/MC composite films. Copyright © 2017 Elsevier Ltd. All rights reserved.

a Facile Synthesis of Fully Porous Tazo Composite and its Remarkable Gas Sensitive Performance

NASA Astrophysics Data System (ADS)

Liang, Dongdong; Liu, Shimin; Wang, Zhinuo; Guo, Yu; Jiang, Weiwei; Liu, Chaoqian; Ding, Wanyu; Wang, Hualin; Wang, Nan; Zhang, Zhihua

The composite of a nanocrystalline SnO2 thick film deposited on an Al-doped ZnO ceramic substrate was firstly proposed. This study also provided a simple, fast and cost effective method to prepare SnO2 thick film and Al-doped ZnO ceramic as well as the final composite. The crystal structure, morphology, composition, pore size distribution and gas sensitivity of the composite were investigated by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, Barrett-Joyner-Halenda analysis and gas sensitive measurement system. Results indicated that the composite was fully porous consisted of SnO2, ZnO and ZnAl2O4 crystal phases. The macrosized pores generated in the composite could enhance the gas infiltration into the sensing layers effectively. In this way, combining a high gas-transporting-capability and a nanocrystalline SnO2 thick film, the composite showed very impressive performance. The gas sensitivity of the composite was high enough for ethanol vapor with different concentrations, which was comparable to other kinds of reported SnO2 gas sensors, while showing two straight lines with a turning point at 1000ppm. Finally, the gas sensitive mechanism was proposed based on the microstructure and composition of the composite.

Physicochemical, microstructural, and antibacterial properties of β-chitosan and kudzu starch composite films.

PubMed

Zhong, Yu; Li, Yunfei; Zhao, Yanyun

2012-10-01

This study investigated physicochemical, microstructural, and antibacterial properties of β-chitosan-kudzu starch composite films with addition of 0%, 20%, 60%, or 100% kudzu starch (w starch/w chitosan) in 1% chitosan solution. Molecular interactions between chitosan and kudzu starch and the crystal structure of the films were also determined. Adding 60% kudzu starch reduced water vapor permeability and solubility of pure β-chitosan film by about 15% and 20%, respectively, whereas mechanical strength and flexibility of the film were increased about 50% and 25%, respectively. Micrograph showed that β-chitosan film was totally amorphous, and the composite films generally became rougher with more starch added. Fourier transform infrared and X-ray diffraction spectra showed that the 2 film-forming components were compatible with each other. Pure β-chitosan film resulted in 9.5 and 11.5 log CFU/mL reduction in Escherichia coli and Listeria innocua based on plate count method, respectively. Addition of kudzu starch reduced the antibacterial activity of film, but still achieved 8.3 and 10.3 log CFU/mL reduction in E. coli and L. innocua, respectively when kudzu starch to chitosan weight ratio was 1:1. Reduced antibacterial activity might attribute to the interaction of amino groups in β-chitosan with the hydroxyl groups in kudzu starch. This study demonstrated that kudzu starch effectively improved water barrier of β-chitosan film, and the composite films retained strong antibacterial ability. One percent of β-chitosan containing 60% kudzu starch (w/w chitosan) composite films possessed better mechanical and water barrier properties than pure β-chitosan films, and showed strong antibacterial activity against both Gram-positive and Gram-negative bacteria. The films may be used as wraps or coatings to prolong the shelf life of different foods or other similar applications. © 2012 Institute of Food Technologists®

Effect of Hydroxyl Concentration on Chemical Sensitivity of Polyvinyl Alcohol/Carbon-Black Composite Chemiresistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hughes, Robert C.; Patel, Sanjay V.; Yelton, W. Graham

1999-05-19

The sensitivity and selectivity of polyvinyl alcohol (PVA) / carbon black composite films have been found to vary depending upon the hydroxylation percentage ("-OH") of the polymer. These chemiresistors made from PVA films whose polymer backbone is 88% hydroxylated (PVA88) have a high sensitivity to water, while chemiresistors made from PVA75 have a higher sensitivity to methanol. The minor differences in polymer composition result in films with different Hildebrand volubility parameters. The relative responses of several different PVA-based chemiresistors to solvents with different volubility parameters are presented. In addition, polyvinyl acetate (PVAC) films with PVA88 are used in an arraymore » to distinguish the responses to methanol-water mixtures.« less

Antimicrobial property and microstructure of micro-emulsion edible composite films against Listeria.

PubMed

Guo, Mingming; Jin, Tony Z; Yadav, Madhav P; Yang, Ruijin

2015-09-02

Edible antimicrobial composite films from micro-emulsions containing all natural compounds were developed and their antimicrobial properties and microstructures were investigated. Chitosan, allyl isothiocyanate (AIT), barley straw arabinoxylan (BSAX), and organic acids (acetic, lactic and levulinic acids) were used as film-forming agent, antimicrobial agent, emulsifier, and solvent, respectively. Micro-emulsions were obtained using high pressure homogenization (HPH) processing at 138MPa for 3cycles. The composite films made from the micro-emulsions significantly (p<0.05) inactivated Listeria innocua in tryptic soy broth (TSB) and on the surface of ready-to-eat (RTE) meat samples, achieving microbial reductions of over 4logCFU/ml in TSB after 2days at 22°C and on meat samples after 35days at 10°C. AIT was a major contributor to the antimicrobial property of the films and HPH processing further enhanced its antimicrobial efficacy, while the increase of chitosan from 1.5% to 3%, or addition of acetic acid to the formulations didn't result in additional antimicrobial effects. This study demonstrated an effective approach to developing new edible antimicrobial films and coatings used for food applications. Published by Elsevier B.V.

Optical properties of MgF2 nano-composite films dispersed with noble metal nanoparticles synthesized by sol-gel method

NASA Astrophysics Data System (ADS)

Wakaki, Moriaki; Soujima, Nobuaki; Shibuya, Takehisa

2015-03-01

Porous MgF2 films synthesized by a sol-gel method exhibit the lowest refractive index among the dielectric optical materials and are the most useful materials for the anti-reflection coatings. On the other hand, surface plasmon resonance (SPR) absorptions of noble metal nanoparticles in various solid matrices have been extensively studied. New functional materials like a SERS (Surface Enhanced Raman Spectroscopy) tips are expected by synthesizing composite materials between porous MgF2 films featured by the network of MgF2 nanoparticles and noble metal nanoparticles introduced within the network. In this study, fundamental physical properties including morphology and optical properties are characterized for these materials to make clear the potential of the composite system. Composite materials of MgF2 films dispersed with noble metal (Ag, Au) nanoparticles were prepared using the sol-gel technique with various annealing temperatures and densities of noble metal nanoparticles. The structural morphology was analyzed by an X-ray diffractometer (XRD) and a scanning electron microscope (SEM). The size and shape distributions of the metal nanoparticles were observed using a transmission electron microscope (TEM). The optical properties of fabricated composite films were characterized by UV-Vis-NIR and FT-IR spectrophotometers. The absorption spectra due to the surface plasmon resonance (SPR) of the metal nanoparticles were analyzed using the dielectric function considering the effective medium approximation, typically Maxwell-Garnett model. The Raman scattering spectra were also studied to check the enhancement effect of specimen dropped on the MgF2: Ag nano-composite films deposited on Si substrate. Enhancement of the Raman intensity of pyridine solution specimen was observed.

The Effect of Film Composition on the Texture and Grain Size of CuInS2 Prepared by Spray Pyrolysis

NASA Technical Reports Server (NTRS)

Jin, Michael H.-C.; Banger, Kulbinder K.; Harris, Jerry D.; Hepp, Aloysius F.

2003-01-01

CuInS2 was deposited by spray pyrolysis using single-source precursors synthesized in-house. Films with either (112) or (204/220) preferred orientation always showed Cu-rich and In-rich composition respectively. The In-rich (204/220)-oriented films always contained a secondary phase evaluated as an In-rich compound, and the hindrance of (112)-oriented grain growth was confirmed by glancing angle X-ray diffraction. In conclusion, only the Cu-rich (112)-oriented films with dense columnar grains can be prepared without the secondary In-rich compound. The effect of extra Cu on the grain size and the solar cell results will be also presented.

Electrochemical synthesis of Sm2O3 nanoparticles: Application in conductive polymer composite films for supercapacitors.

PubMed

Mohammad Shiri, Hamid; Ehsani, Ali; Jalali Khales, Mina

2017-11-01

A novel electrosynthetic method was introduced to synthesize of Sm 2 O 3 nanoparticles and furthermore, for improving the electrochemical performance of conductive polymer, hybrid POAP/Sm 2 O 3 films have then been fabricated by POAP electropolymerization in the presence of Sm 2 O 3 nanoparticles as active electrodes for electrochemical supercapacitors. The structure, morphology, chemical composition of Sm 2 O 3 nanoparticles was examined. Surface and electrochemical analyses have been used for characterization of Sm 2 O 3 and POAP/Sm 2 O 3 composite films. Different electrochemical methods including galvanostatic charge discharge experiments, cyclic voltammetry and electrochemical impedance spectroscopy have been applied to study the system performance. The supercapacity behavior of the composite film was attributed to the (i) high active surface area of the composite, (ii) charge transfer along the polymer chain due to the conjugation form of the polymer and finally (iii) synergism effect between conductive polymer and Sm 2 O 3 nanoparticles. Copyright © 2017 Elsevier Inc. All rights reserved.

Superconducting properties of Nb-Cu nano-composites and nano-alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parab, Pradnya, E-mail: pradnyaprb@gmail.com; Kumar, Sanjeev; Bhui, Prabhjyot

The evolution of the superconducting transition temperature (T{sub c}) in nano-composite and nano-alloys of Nb-Cu, grown by DC magnetron co-sputtering are investigated. Microstructure of these films depends less strongly on the ratio of Nb:Cu but more on the growth temperature. At higher growth temperature, phase separated granular films of Nb and Cu were formed which showed superconducting transition temperatures (T{sub c}) of ~ 7.2±0.5 K, irrespective of the composition. Our results show that this is primarily influenced by the microstructure of the films determined during growth which rules out the superconducting proximity effect expected in these systems. At room temperaturemore » growth, films with nano-scale alloying were obtained at the optimal compositional range of 45-70 atomic% (At%) of Nb. These were also superconducting with a T{sub c} of 3.2 K.« less

Effect of solution concentration on MEH-PPV thin films

NASA Astrophysics Data System (ADS)

Affendi, I. H. H.; Sarah, M. S. P.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2018-05-01

MEH-PPV thin films were prepared with a mixture of THF (tetrahydrofuran) solution deposited by spin coating method. The surface topology of MEH-PPV thin film were characterize by atomic force microscopy (AFM) and optical properties of absorption spectra were characterized by using Ultraviolet-visible-near-infrared (UV-Vis-NIR). The MEH-PPV concentration variation affects the surface and optical properties of the thin film where 0.5 mg/ml MEH-PPV concentration have a good surface topology provided the same film also gives the highest absorption coefficient were then deposited to a TiO2 thin film forming composite layer. The composite layer then shows low current flow of short circuit current of Isc = -5.313E-7 A.

Electrochemical synthesis of poly(pyrrole-co-o-anisidine)/chitosan composite films

NASA Astrophysics Data System (ADS)

Yalçınkaya, Süleyman; Çakmak, Didem

2017-05-01

In this study, poly(pyrrole-co-o-anisidine)/chitosan composite films were electrochemically synthesized in various monomers feed ratio (pyrrole: o-anisidine; 9:1, 7:3, 1:1, 3:7 and 1:9) of pyrrole and o-anisidine on the platinum electrode. Electrochemical synthesis of the composite films was carried out via cyclic voltammetry technique. They were characterized by FT-IR, cyclic voltammetry, SEM micrographs, digital images, TGA and DSC techniques. The SEM results indicated that the particle size of the composite decreased with increasing o-anisidine ratio and the films became more likely to be smooth morphology. The TGA results proved that the film of the composite with 1:1 ratio showed highest final degradation temperature and lowest weight loss (83%) compared to copolymer and 9:1 1:9 composite films. The 1:1 composite film had higher thermal stability than copolymer and the other composite films (9:1 1:9). Meanwhile, electrochemical studies exhibited that the 1/9 composite film had good electrochemical stability as well.

Effect of Sn Content in a CuSnZn Metal Precursor on Formation of MoSe2 Film during Selenization in Se+SnSe Vapor

PubMed Central

Yao, Liyong; Ao, Jianping; Jeng, Ming-Jer; Bi, Jinlian; Gao, Shoushuai; Sun, Guozhong; He, Qing; Zhou, Zhiqiang; Sun, Yun; Chang, Liann-Be

2016-01-01

The preparation of Cu2ZnSnSe4 (CZTSe) thin films by the selenization of an electrodeposited copper–tin–zinc (CuSnZn) precursor with various Sn contents in low-pressure Se+SnSex vapor was studied. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) measurements revealed that the Sn content of the precursor that is used in selenization in a low-pressure Se+SnSex vapor atmosphere only slightly affects the elemental composition of the formed CZTSe films. However, the Sn content of the precursor significantly affects the grain size and surface morphology of CZTSe films. A metal precursor with a very Sn-poor composition produces CZTSe films with large grains and a rough surface, while a metal precursor with a very Sn-rich composition procures CZTSe films with small grains and a compact surface. X-ray diffraction (XRD) and SEM revealed that the metal precursor with a Sn-rich composition can grow a thicker MoSe2 thin film at CZTSe/Mo interface than one with a Sn-poor composition, possibly because excess Sn in the precursor may catalyze the formation of MoSe2 thin film. A CZTSe solar cell with an efficiency of 7.94%was realized by using an electrodeposited metal precursor with a Sn/Cu ratio of 0.5 in selenization in a low-pressure Se+SnSex vapor. PMID:28773366

Conducting polymer composite film incorporated with aligned carbon nanotubes for transparent, flexible and efficient supercapacitor

PubMed Central

Lin, Huijuan; Li, Li; Ren, Jing; Cai, Zhenbo; Qiu, Longbin; Yang, Zhibin; Peng, Huisheng

2013-01-01

Polyaniline composite films incorporated with aligned multi-walled carbon nanotubes (MWCNTs) are synthesized through an easy electrodeposition process. These robust and electrically conductive films are found to function as effective electrodes to fabricate transparent and flexible supercapacitors with a maximum specific capacitance of 233 F/g at a current density of 1 A/g. It is 36 times of bare MWCNT sheet, 23 times of pure polyaniline and 3 times of randomly dispersed MWCNT/polyaniline film under the same conditions. The novel supercapacitors also show a high cyclic stability. PMID:23443325

Fabrication de couches minces a memoire de forme et effets de l'irradiation ionique

NASA Astrophysics Data System (ADS)

Goldberg, Florent

1998-09-01

Nickel and titanium when combined in the right stoichiometric proportion (1:1) can form alloys showing the shape memory effect. Within the scope of this thesis, thin films of such alloys have been successfully produced by sputtering. Precise control of composition is crucial in order to obtain the shape memory effect. A combination of analytical tools which can accurately determine the behavior of such materials is also required (calorimetric analysis, crystallography, composition analysis, etc.). Rutherford backscattering spectrometry has been used for quantitative composition analysis. Thereafter irradiation of films with light ions (He+) of few MeV was shown to allow lowering of the characteristic premartensitic transformation temperatures while preserving the shape memory effect. Those results open the door to a new field of research, particularly for ion irradiation and its potential use as a tool to modify the thermomechanical behavior of shape memory thin film actuators.

Antibacterial Composite Film-Based Triboelectric Nanogenerator for Harvesting Walking Energy.

PubMed

Gu, Guang Qin; Han, Chang Bao; Tian, Jing Jing; Lu, Cun Xin; He, Chuan; Jiang, Tao; Li, Zhou; Wang, Zhong Lin

2017-04-05

As a green and eco-friendly technology, triboelectric nanogenerator (TENG) can harvest energy from human motion to generate electricity, so TENGs have been widely applied in wearable electronic devices to replace traditional batteries. However, the surface of these TENGs is easily contaminated and breeds bacteria, which is a threat to human health. Here, we report an antibacterial composite film-based triboelectric nanogenerator (ACF-TENG) that uses Ag-exchanged zeolite (Ag-zeolite) and polypropylene (PP) composite film as the triboelectric layer. Adding a small amount of Ag-zeolite with excellent antibacterial properties can increase the dielectric permittivity and improve the surface charge density of composite films, which enhances the output performance of the ACF-TENG. The open-circuit voltage (V OC ), short-circuit current (I SC ), and transferred charge (Q Tr ) of the ACF-TENG are about 193.3, 225.4, and 233.3% of those of a pure PP film-based TENG, respectively. Because of the silver in the Ag-zeolite, the ACF-TENG can effectively kill Escherichia coli and fungi. When used in insoles, the ACF-TENG can resist the athlete's foot fungus effectively and work as a power source to light up light-emitting diodes and charge capacitors. The ACF-TENG has wide application prospects in self-powered medical and healthcare electronics.

Chitosan/alginate multilayer film for controlled release of IDM on Cu/LDPE composite intrauterine devices.

PubMed

Tian, Kuan; Xie, Changsheng; Xia, Xianping

2013-09-01

To reduce such side effects as pain and bleeding caused by copper-containing intrauterine device (Cu-IUD), a novel medicated intrauterine device, which is coated with an indomethacin (IDM) delivery system on the surface of copper/low-density polyethylene (Cu/LDPE) composite intrauterine device, has been proposed and developed in the present work. The IDM delivery system is a polyelectrolyte multilayer film, which is composed of IDM containing chitosan and alginate layer by layer, is prepared by using self-assembled polyelectrolyte multilayer method, and the number of the layers of this IDM containing chitosan/alginate multilayer film can be tailored by controlling the cyclic repetition of the deposition process. After the IDM containing chitosan/alginate multilayer film is obtained on the surface of Cu/LDPE composite intrauterine device, its release behavior of both IDM and cupric ion has been studied in vitro. The results show that the release duration of IDM increase with the increasing of thickness of the IDM containing chitosan/alginate multilayer film, and the initial burst release of cupric ion cannot be found in this novel medicated Cu/LDPE composite IUD. These results can be applied to guide the design of novel medicated Cu-IUD with minimal side effects for the future clinical use. Copyright © 2013 Elsevier B.V. All rights reserved.

Effect of counterface material type and its topography on the tribological properties of polyimide composites

NASA Technical Reports Server (NTRS)

Fusaro, R. L.

1985-01-01

Graphite fiber reinforced polyimide composite pins were slid against seven different counterfaces to determine the effect of material type on the tribological properties of polymer composites. In addition, the effect of sliding a new pin on a pre-established transfer film was investigated. The results indicated that almost a five order of magnitude difference in composite wear rate can occur just by varying the counterface material. An attempt to make all surfaces as smooth as possible was made, but due to differences in material composition this was not possible and a range of surface roughnesses were obtained. The results indicate that the smoother the surface, the lower the composite wear rate; but that small protrusions (not discernible with arithmetic surface roughness measurements) can markedly increase wear rates. A pre-established transfer film improved both run in and steady state wear rates.

99 Films on Drugs.

ERIC Educational Resources Information Center

Weber, David O., Ed.

This catalog describes and evaluates 16-millimeter films about various aspects of drug use. Among the subjects covered by the 99 films are the composition and effects of different drugs, reasons why people use drugs, life in the drug culture, the problem of law enforcement, and various means of dealing with drug users. Each film is synopsized. Two…

Effects of glycine and current density on the mechanism of electrodeposition, composition and properties of Ni-Mn films prepared in ionic liquid

NASA Astrophysics Data System (ADS)

Guo, Jiacheng; Guo, Xingwu; Wang, Shaohua; Zhang, Zhicheng; Dong, Jie; Peng, Liming; Ding, Wenjiang

2016-03-01

The effects of glycine on the mechanism of electrodeposition of Ni-Mn alloy film prepared in ChCl-urea ionic liquid were studied in order to control the composition, microstructure and properties of the film. The cyclic voltammograms revealed that the presence of glycine in the ionic liquid can inhibit the reduction of Ni2+ ions but promote the reduction of Mn2+ ions in the cathodic scan. However, it promoted the dissolution of both Ni and Mn deposits in the ChCl-urea ionic liquids during the reverse scan. Glycine changed the mode of Ni-Mn film growth from Volmer-Weber mode into Stranski-Krastanov mode. The Mn content in the Ni-Mn film increased with the increase of concentration of glycine and current density. The Ni-Mn alloy film with 3.1 at.% Mn exhibited the lowest corrosion current density of 3 × 10-7 A/cm2 compared with other films prepared and exhibited better corrosion resistance than pure Ni film in 3.5 wt.% NaCl solution.

Effect of post-treatments and concentration of cotton linter cellulose nanocrystals on the properties of agar-based nanocomposite films.

PubMed

Oun, Ahmed A; Rhim, Jong-Whan

2015-12-10

Cellulose nanocrystals (CNCs) were prepared by acid hydrolysis of cotton linter pulp fibers and three different purification methods, i.e., without post purification (CNC1), dialyzed against distilled water (CNC2), and neutralized with NaOH (CNC3), and their effect on film properties was evaluated by preparation of agar/CNCs composite films. All the CNCs were rod in shape with diameter of 15-50 nm and length of 210-480 nm. FTIR result indicated that there was no distinctive differences in the chemical structure between CNCs and cotton linter cellulose fiber. No significant relationship was observed between the sulfate content and crystallinity index of CNCs. The CNC3 showed higher thermal stability than the other type of CNCs due to the less adverse effect on the thermal stability of sulfate groups induced by the neutralization with NaOH. The tensile strength (TS) of agar film increased by 15% with incorporation of 5 wt% of CNC3, on the contrary, it decreased by 10% and 15% with incorporation of CNC1 and CNC2, respectively. Other performance properties of agar/CNCs composite films such as optical and water vapor barrier properties showed that the CNC3 was more effective filler than the other CNCs. In the range of concentration of CNC3 tested (1-10 wt%), inclusion of 5 wt% of CNC3 was the maximum concentration for improving or maintaining film properties of the composite films. The neutralization of acid hydrolyzed cellulose using NaOH was simple and convenient for the preparation of CNC and bionanocomposite films. Copyright © 2015 Elsevier Ltd. All rights reserved.

Erosion of fluorinated diamond-like carbon films by exposure to soft X-rays

NASA Astrophysics Data System (ADS)

Kanda, Kazuhiro; Takamatsu, Hiroki; Miura-Fujiwara, Eri; Akasaka, Hiroki; Saiga, Akihiro; Tamada, Koji

2018-04-01

The effects of soft X-ray irradiation on fluorinated diamond-like carbon (F-DLC) films were investigated using synchrotron radiation (SR). The Vickers hardness of the F-DLC films substantially increased from an initial value of about 290 to about 800 HV at a dose of 50 mA·h and the remained constant at about 1100 HV at doses of more than 300 mA·h. This dose dependence was consistent with those of the film thickness and elemental composition. The depth profile of the elemental composition inside each F-DLC film obtained by the measurement of the X-ray photoelectron spectrum (XPS) during sputtering showed that the composition ratio of fluorine was approximately constant from the surface to the neighborhood of the substrate. Namely, fluorine atoms were desorbed by SR irradiation from not only the surface but also the substrate neighborhood. Modification by SR irradiation was found to occur in the entire F-DLC film of about 200 nm thickness.

The effect of chitosan and whey proteins-chitosan films on the growth of Penicillium expansum in apples.

PubMed

Simonaitiene, Dovile; Brink, Ieva; Sipailiene, Ausra; Leskauskaite, Daiva

2015-05-01

Penicillium expansum causes a major post-harvest disease of apples. The aim of this study was to investigate the inhibition effect of chitosan and whey proteins-chitosan films containing different amounts of quince and cranberry juice against P. expansum on the simulation medium and on apples. The mechanical properties of films were also evaluated. The presence of cranberry and quince juice in the composition of chitosan and whey proteins-chitosan films caused a significant (P ≤ 0.05) increase in elasticity and decrease in tensile strength of films. Chitosan and whey proteins-chitosan films with quince and cranberry juice demonstrated a significant (P ≤ 0.05) inhibition effect against P. expansum growth on the simulated medium and apples. The presence of cranberry juice in the composition of chitosan and whey proteins-chitosan films resulted in a longer lag phase and a lower P. expansum growth rate on the simulation medium in comparison with films made with the addition of quince juice. These differences were not evident when experiment was conducted with apples. Addition of quince and cranberry juice to the chitosan and whey proteins-chitosan films as natural antifungal agents has some potential for prolonging the shelf life of apples. © 2014 Society of Chemical Industry.

Correlation Between Optical Properties And Chemical Composition Of Sputter-deposited Germanium Cxide (GeO x) Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murphy, Neil R.; Grant, J. T.; Sun, L.

2014-03-18

Germanium oxide (GeO x) films were grown on (1 0 0) Si substrates by reactive Direct-Current (DC) magnetron sputter-deposition using an elemental Ge target. The effects of oxygen gas fraction, Г = O 2/(Ar + O 2), on the deposition rate, structure, chemical composition and optical properties of GeOx films have been investigated. The chemistry of the films exhibits an evolution from pure Ge to mixed Ge + GeO + GeO 2 and then finally to GeO 2 upon increasing Г from 0.00 to 1.00. Grazing incidence X-ray analysis indicates that the GeO x films grown were amorphous. The opticalmore » properties probed by spectroscopic ellipsometry indicate that the effect of Г is significant on the optical constants of the GeO x films. The measured index of refraction (n) at a wavelength (λ) of 550 nm is 4.67 for films grown without any oxygen, indicating behavior characteristic of semiconducting Ge. The transition from germanium to mixed Ge + GeO + GeO 2 composition is associated with a characteristic decrease in n (λ = 550 nm) to 2.62 and occurs at Г = 0.25. Finally n drops to 1.60 for Г = 0.50–1.00, where the films become GeO 2. A detailed correlation between Г, n, k and stoichiometry in DC sputtered GeO x films is presented and discussed.« less

Characteristic of EBT-XD and EBT3 radiochromic film dosimetry for photon and proton beams

NASA Astrophysics Data System (ADS)

Khachonkham, Suphalak; Dreindl, Ralf; Heilemann, Gerd; Lechner, Wolfgang; Fuchs, Hermann; Palmans, Hugo; Georg, Dietmar; Kuess, Peter

2018-03-01

Recently, a new type of radiochromic film, the EBT-XD film, has been introduced for high dose radiotherapy. The EBT-XD film contains the same structure as the EBT3 film but has a slightly different composition and a thinner active layer. This study benchmarks the EBT-XD against EBT3 film for 6 MV and 10 MV photon beams, as well as for 97.4 MeV and 148.2 MeV proton beams and 15-100 kV x-rays. Dosimetric and film reading characteristics, such as post irradiation darkening, film orientation effect, lateral response artifact (LRA), film sensitivity, energy and beam quality dependency were investigated. Furthermore, quenching effects in the Bragg peak were investigated for a single proton beam energy for both film types, in addition measurements were performed in a spread-out Bragg peak. EBT-XD films showed the same characteristic on film darkening as EBT3. The effects between portrait and landscape orientation were reduced by 3.1% (in pixel value) for EBT-XD compared to EBT3 at a dose of 2000 cGy. The LRA is reduced for EBT-XD films for all investigated dose ranges. The sensitivity of EBT-XD films is superior to EBT3 for doses higher than 500 cGy. In addition, EBT-XD showed a similar dosimetric response for photon and proton irradiation with low energy and beam quality dependency. A quenching effect of 10% was found for both film types. The slight decrease in the thickness of the active layer and different composition configuration of EBT-XD resulted in a reduced film orientation effect and LRA, as well as a sensitivity increase in high-dose regions for both photon and proton beams. Overall, the EBT-XD film improved regarding film reading characteristics and showed advantages in the high-dose region for photon and proton beams.

Characteristic of EBT-XD and EBT3 radiochromic film dosimetry for photon and proton beams.

PubMed

Khachonkham, Suphalak; Dreindl, Ralf; Heilemann, Gerd; Lechner, Wolfgang; Fuchs, Hermann; Palmans, Hugo; Georg, Dietmar; Kuess, Peter

2018-03-15

Recently, a new type of radiochromic film, the EBT-XD film, has been introduced for high dose radiotherapy. The EBT-XD film contains the same structure as the EBT3 film but has a slightly different composition and a thinner active layer. This study benchmarks the EBT-XD against EBT3 film for 6 MV and 10 MV photon beams, as well as for 97.4 MeV and 148.2 MeV proton beams and 15-100 kV x-rays. Dosimetric and film reading characteristics, such as post irradiation darkening, film orientation effect, lateral response artifact (LRA), film sensitivity, energy and beam quality dependency were investigated. Furthermore, quenching effects in the Bragg peak were investigated for a single proton beam energy for both film types, in addition measurements were performed in a spread-out Bragg peak. EBT-XD films showed the same characteristic on film darkening as EBT3. The effects between portrait and landscape orientation were reduced by 3.1% (in pixel value) for EBT-XD compared to EBT3 at a dose of 2000 cGy. The LRA is reduced for EBT-XD films for all investigated dose ranges. The sensitivity of EBT-XD films is superior to EBT3 for doses higher than 500 cGy. In addition, EBT-XD showed a similar dosimetric response for photon and proton irradiation with low energy and beam quality dependency. A quenching effect of 10% was found for both film types. The slight decrease in the thickness of the active layer and different composition configuration of EBT-XD resulted in a reduced film orientation effect and LRA, as well as a sensitivity increase in high-dose regions for both photon and proton beams. Overall, the EBT-XD film improved regarding film reading characteristics and showed advantages in the high-dose region for photon and proton beams.

Large-scale fabrication of linear low density polyethylene/layered double hydroxides composite films with enhanced heat retention, thermal, mechanical, optical and water vapor barrier properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Jiazhuo; Zhang, Kun; Zhao, Qinghua

Novel LDH intercalated with organic aliphatic long-chain anion was large-scale synthesized innovatively by high-energy ball milling in one pot. The linear low density polyethylene (LLDPE)/layered double hydroxides (LDH) composite films with enhanced heat retention, thermal, mechanical, optical and water vapor barrier properties were fabricated by melt blending and blowing process. FT IR, XRD, SEM results show that LDH particles were dispersed uniformly in the LLDPE composite films. Particularly, LLDPE composite film with 1% LDH exhibited the optimal performance among all the composite films with a 60.36% enhancement in the water vapor barrier property and a 45.73 °C increase in themore » temperature of maximum mass loss rate compared with pure LLDPE film. Furthermore, the improved infrared absorbance (1180–914 cm{sup −1}) of LLDPE/LDH films revealed the significant enhancement of heat retention. Therefore, this study prompts the application of LLDPE/LDH films as agricultural films with superior heat retention. - Graphical abstract: The fabrication process of LLDPE/LDH composite films. - Highlights: • LDH with basal spacing of 4.07 nm was synthesized by high-energy ball milling. • LLDPE composite films with homogeneous LDH dispersion were fabricated. • The properties of LLDPE/LDH composite films were improved. • LLDPE/LDH composite films show superior heat retention property.« less

Study on preferred crystal orientations of Mg-Zr-O composite protective layer in AC-PDP

NASA Astrophysics Data System (ADS)

Bingang, G.; Chunliang, L.; Zhongxiao, S.; Liu, L.; Yufeng, F.; Xing, X.; Duowang, F.

2006-11-01

In order to study the preferred crystal orientations of Mg-Zr-O composite protective layers in PDP, Mg-Zr-O composite protective layers were deposited by Electron-beam Evaporator using (MgO+ZrO{2}) powder mixture as evaporation source material. X-ray diffractometer (XRD) was used to determine preferred crystal orientations of Mg-Zr-O composite protective layers, surface morphologies of films were analyzed by FESEM and voltage characteristics were examined in a testing macroscopic discharge cell of AC-PDP. On the basis of experimental analysis, the influence of oxide addition and deposition conditions on preferred orientations of Mg-Zr-O composite protective layers were investigated. The results showed that the preferred orientations of Mg-Zr-O films were determined by lattice distortion of MgO crystal. The deposition conditions have great effects on the preferred orientations of Mg-Zr-O films. The preferred orientations affect voltage characteristics through affecting surface morphology of Mg-Zr-O films. A small amount of Zr solution in MgO can decrease firing voltage compared with using pure MgO film. Firing voltage is closely related with the [ ZrO{2}/(MgO+ZrO{2})] ratio of evaporation source materials.

Room-temperature wide-range luminescence and structural, optical, and electrical properties of SILAR deposited Cu-Zn-S nano-structured thin films

NASA Astrophysics Data System (ADS)

Jose, Edwin; Kumar, M. C. Santhosh

2016-09-01

We report the deposition of nanostructured Cu-Zn-S composite thin films by Successive Ionic Layer Adsorption and Reaction (SILAR) method on glass substrates at room temperature. The structural, morphological, optical, photoluminescence and electrical properties of Cu-Zn-S thin films are investigated. The results of X-ray diffraction (XRD) and Raman spectroscopy studies indicate that the films exhibit a ternary Cu-Zn-S structure rather than the Cu xS and ZnS binary composite. Scanning electron microscope (SEM) studies show that the Cu-Zn-S films are covered well over glass substrates. The optical band gap energies of the Cu-Zn-S films are calculated using UV-visible absorption measurements, which are found in the range of 2.2 to 2.32 eV. The room temperature photoluminescence studies show a wide range of emissions from 410 nm to 565 nm. These emissions are mainly due to defects and vacancies in the composite system. The electrical studies using Hall effect measurements show that the Cu-Zn-S films are having p-type conductivity.

Giant negative electrocaloric effect in PbZrO3/0.88BaTiO3-0.12Bi(Mg1/2,Ti1/2)O3 multilayered composite ferroelectric thin film for solid-state refrigeration

NASA Astrophysics Data System (ADS)

Huang, D.; Wang, J. B.; Zhong, X. L.; Li, B.; Zhang, Y.; Jin, C.; Zheng, D. F.; Meng, X. J.

2017-11-01

A giant negative electrocaloric (EC) effect in a PbZrO3/(0.88BaTiO3-0.12 Bi(Mg1/2,Ti1/2)O3) (PZ/(BT-BMT)) multilayered composite ferroelectric (MCFE) thin film which is grown on Pt(111)/Ti/SiO2/Si(100) substrates by the sol-gel method is investigated in this work. The negative EC effect in the PZ/(BMT-BT) MCFE thin film is greatly higher than that in the PZ AFE thin film with an adiabatic temperature change (ATC) ΔT = 1.5 K. The ATC ΔT of the PZ/(BMT-BT) MCFE thin film is -32 K under the applied electric field change ΔE = 1151 kV/cm. The result is conducive to enhance the EC refrigeration efficiency greatly.

Enhanced photocathodic protection performance of Ag/graphene/TiO2 composite for 304SS under visible light.

PubMed

Li, Hong; Wang, Xiutong; Wei, Qinyi; Liu, Xueqing; Qian, Zhouhai; Hou, Baorong

2017-06-02

Ag and graphene co-sensitized TiO 2 composites were successfully fabricated and used as photoanodes for photogenerated cathodic protection of 304 stainless steel (304SS) under visible light. Graphene films was firstly deposited onto the TiO 2 nanotube (NT) films via cyclic voltammetric electrodeposition. Ag/graphene/TiO 2 films were then fabricated via dipping and photoreduction method. The morphology, composition and optical response of the Ag/graphene/TiO 2 NT composites were characterized by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, UV-vis diffusion reflectance spectroscopy, respectively. The photocathodic protection performance of the Ag/graphene/TiO 2 composites were systematically studied through open-circuit potential and potentiodynamic polarization measurements in 3.5 wt% NaCl solution under visible light (λ > 400 nm). The composites exhibited enhanced photogenerated cathodic protection performance for 304SS under visible light irradiation compared to pure TiO 2 . Graphene and Ag have a synergistic effect on the enhancement of photocathodic protection performance of TiO 2 . The composites prepared with 30-cycle graphene film and 15 mM AgNO 3 solution showed the optimal corrosion protection performance.

Enhanced photocathodic protection performance of Ag/graphene/TiO2 composite for 304SS under visible light

NASA Astrophysics Data System (ADS)

Li, Hong; Wang, Xiutong; Wei, Qinyi; Liu, Xueqing; Qian, Zhouhai; Hou, Baorong

2017-06-01

Ag and graphene co-sensitized TiO2 composites were successfully fabricated and used as photoanodes for photogenerated cathodic protection of 304 stainless steel (304SS) under visible light. Graphene films was firstly deposited onto the TiO2 nanotube (NT) films via cyclic voltammetric electrodeposition. Ag/graphene/TiO2 films were then fabricated via dipping and photoreduction method. The morphology, composition and optical response of the Ag/graphene/TiO2 NT composites were characterized by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, UV-vis diffusion reflectance spectroscopy, respectively. The photocathodic protection performance of the Ag/graphene/TiO2 composites were systematically studied through open-circuit potential and potentiodynamic polarization measurements in 3.5 wt% NaCl solution under visible light (λ > 400 nm). The composites exhibited enhanced photogenerated cathodic protection performance for 304SS under visible light irradiation compared to pure TiO2. Graphene and Ag have a synergistic effect on the enhancement of photocathodic protection performance of TiO2. The composites prepared with 30-cycle graphene film and 15 mM AgNO3 solution showed the optimal corrosion protection performance.

Nanocomposite film of TiO{sub 2} nanotube and polyoxometalate towards photocatalytic degradation of nitrobenzene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Zhixia; Zhao, Mingliang; Li, Fengyan, E-mail: lify525@nenu.edu.cn

2014-12-15

Highlights: • The film of POMs and TiO{sub 2} nanotubes was prepared by electrodeposition. • The photocatalytic activity of the composite film for nitrobenzene was investigated. • The composite film showed higher photocatalytic activity than pure TiO{sub 2} nanotubes. • The introduction of POMs into TiO{sub 2} could retard electron–hole recombination. - Abstract: The composite film based on polyoxometalates (POMs)-modified TiO{sub 2} nanotubes was prepared by electrodeposition method for the photocatalytic degradation of nitrobenzene. The composite film was characterized by field-emission scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, which indicated that the POMs weremore » well introduced into the TiO{sub 2} nanotubes. Furthermore, the photocatalytic properties of the TiO{sub 2} nanotubes and POMs-modified TiO{sub 2} nanotubes were evaluated by the decomposition of nitrobenzene. POMs-modified TiO{sub 2} nanotubes showed much higher photocatalytic activity than pure TiO{sub 2} nanotubes. These results provide a promising route to effectively photocatalytic degradation of nitrobenzene by POMs-modified TiO{sub 2} nanotubes.« less

Z-scan measurement for nonlinear absorption property of rGO/ZnO:Al thin film

NASA Astrophysics Data System (ADS)

Sreeja, V. G.; Anila, E. I.

2018-04-01

We report the fabrication of reduced graphene oxide integrated aluminium doped zinc oxide (rGO/ZnO:Al) composite thin film on a glass substrate by spin coating technique. The effect of rGO on structural and linear optical properties of rGO/ZnO:Al composite thin film was explored with the help of X-Ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-Vis absorption spectroscopy. Structural studies reveals that the composite film has hexagonal wurtzite structure with a strong bonding between rGO and ZnO:Al material. The band gap energy of ZnO:Al thin film was red shifted by the addition of rGO. The Nonlinear absorption property was investigated by open aperture Z-scan technique by using Q switched Nd-YAG laser at 532nm. The Z-scan results showed that the composite film demonstrates reverse saturable absorption property with a nonlinear absorption coefficient, β, of 12.75×10-7m/w. The results showed that investigated rGO/ZnO:Al thin film is a promising material suitable for the applications in absorbing type optical devices such as optical limiters, optical switches and protection of the optical sensors in the field of nonlinear optics.

Rare-earth substitution in (BiYCa)3(FeSiGe)5O12 bubble films

NASA Technical Reports Server (NTRS)

Luther, L. C.; Slusky, S. E. G.; Brandle, C. D.; Norelli, M. P.

1987-01-01

The substitution of Y by Sm, Tb, Gd, and Ho in (BiYCa)3 FeSiGe)5O12 bubble garnet is shown to have large effects on the growth-induced anisotropy (GIA). The presently accepted film composition intended for 6-or 8-micron-period bubble memory devices demands partial substitution of Y by Gd and Ho. However, comparing films grown under the same growth conditions, it is observed that YGdHoBilG films posess less (GIA) than their Gd, Ho-free counterparts. Thus, to satisfy (GIA) requirements, the supercooling during growth must be increased by 20 K to 80 K with undesirable effects on defect densities. A new film composition containing Sm, Tb, and Gd has been formulated to satisfy all known material property specifications for 6- or 8-micron-period memory devices. It can be grown with only 45-50 K supercooling.

Effect of SiO2 addition on photocatalytic activity, water contact angle and mechanical stability of visible light activated TiO2 thin films applied on stainless steel by a sol gel method

NASA Astrophysics Data System (ADS)

Momeni, Mansour; Saghafian, Hasan; Golestani-Fard, Farhad; Barati, Nastaran; Khanahmadi, Amirhossein

2017-01-01

Nanostructured N doped TiO2/20%SiO2 thin films were developed on steel surface via sol gel method using a painting airbrush. Thin films then were calcined at various temperatures in a range of 400-600 °C. The effect of SiO2 addition on phase composition and microstructural evolution of N doped TiO2 films were studied using XRD and FESEM. Optical properties, visible light photocatalytic activity, hydrophilic behavior, and mechanical behavior of the films were also investigated by DRS, methylene blue degradation, water contact angle measurements, and nanoscratch testing. Results indicated that the band gap energy of N doped TiO2/SiO2 was increased from 2.93 to 3.09 eV. Crack formation during calcination was also significantly promoted in the composite films. All composite films demonstrated weaker visible light photocatalytic activities and lower mechanical stability in comparison with N doped TiO2 films. Moreover, the N doped TiO2/SiO2 film calcined at 600 °C showed undesirable hydrophilic behavior with a water contact angle of 57° after 31 h of visible light irradiation. Outcomes of the present study reveal some different results to previous reports on TiO2/SiO2 films. In general, we believe the differences in substrate material as well as application in visible light are the main reasons for the above mentioned contradiction.

Development of tea extracts and chitosan composite films for active packaging materials.

PubMed

Peng, Yong; Wu, Yan; Li, Yunfei

2013-08-01

The effects of 0.5%, 1% and 2% green tea extracts (GTE) and black tea extracts (BTE) on the physical, structural and antioxidant properties of chitosan films were investigated. Results showed that the addition of tea extracts significantly decreased water vapour permeability and increased the antioxidant ability of films. The DPPH radical scavenging ability of GTE films was stronger than that of BTE films in all food simulants (0%, 20%, 75% and 95% ethanol). The equilibration time in different food simulants decreased with the increased ethanol concentration. DSC and FTIR spectra analysis indicated that there was strong interaction in film matrix, which could be reflected by the physical and mechanical properties of composite films. This study revealed that an active chitosan film could be obtained by incorporation of tea extracts, which may provide new formulation options for developing an antioxidant active packaging. Copyright © 2013 Elsevier B.V. All rights reserved.

Polymeric Luminescent Compositions Doped with Beta-Diketonates Boron Difluoride as Material for Luminescent Solar Concentrator

NASA Astrophysics Data System (ADS)

Khrebtov, A. A.; Fedorenko, E. V.; Reutov, V. A.

2017-11-01

In this paper we investigated polymeric luminescent compositions based on polystyrene doped with beta diketonates boron difluoride. Transparent films with effective absorption in the ultraviolet and blue regions of the spectrum were obtained. Polymeric luminescent compositions based on the mixture of dyes allow expanding the absorption region and increase the radiation shift. A luminescent solar concentrator consisting of a glass plate coated with such film can be used for photovoltaic window application.

Magnetic field-induced strain and magnetoelectric effects in sandwich composite of ferromagnetic shape memory Ni-Mn-Ga crystal and piezoelectric PVDF polymer.

PubMed

Zeng, Min; Or, Siu Wing; Chan, Helen Lai Wa

2010-10-01

A sandwich composite consisting of one layer of ferromagnetic shape memory Ni-Mn-Ga crystal plate bonded between two layers of piezoelectric PVDF polymer film was fabricated, and its magnetic field-induced strain (MFIS) and magnetoelectric (ME) effects were investigated, together with a monolithic Ni-Mn-Ga crystal, as functions of magnetic fields and mechanical load. The load-free dc- and ac-MFISs were 0.35 and 0.05% in the composite, and 5.6 and 0.3% in the monolithic crystal, respectively. The relatively smaller load-free MFISs in the composite than the monolithic crystal resulted from the clamping of martensitic twin-boundary motion in the Ni-Mn-Ga plate by the PVDF films. The largest ME coefficient (α(E)) was 0.58 V/cm·Oe at a magnetic bias field (H(Bias)) of 8.35 kOe under load-free condition. The mechanism of the ME effect originated from the mechanically mediated MFIS effect in the Ni-Mn-Ga plate and piezoelectric effect in the PVDF films. The measured α(E)-H(Bias) responses under different loads showed good agreement with the model prediction.

Development and characterization of an LDPE/chitosan composite antimicrobial film for chilled fish storage.

PubMed

Reesha, K V; Panda, Satyen Kumar; Bindu, J; Varghese, T O

2015-08-01

An antimicrobial packaging material was developed by uniformly embedding 1, 3 and 5% chitosan (w/w) in low density polyethylene matrix using maleic anhydride grafted LDPE as a compatible agent. The materials were mixed by compounding and blown into monolayer films via blown film extrusion. The developed films showed good barrier properties against oxygen. Characterization of the composite films with Fourier transform infrared spectroscopy revealed that chitosan and LDPE interacted well with each other. Overall migration showed better release of chitosan adduct from the LDPE matrix which enhanced the antibacterial properties of the films. The interaction between the LDPE/CS and maleic anhydride grafted LDPE had a decreasing effect on the tensile strength and heat sealing properties. Investigation on antimicrobial properties of LDPE/CS films showed 85-100% inhibition of Escherichia coli. Efficacy of LDPE/CS films was evaluated by using them as packaging material for chilled storage of Tilapia (Oreochromis mossambicus). Analysis of storage quality indices (peroxide value, free fatty acid, total volatile base nitrogen and aerobic plate count) revealed good antibacterial property and extension of shelf life of Tilapia in the chitosan incorporated novel composite films compared to virgin LDPE film. Copyright © 2015 Elsevier B.V. All rights reserved.

Composition- and crystallinity-dependent thermoelectric properties of ternary BixSb2-xTey films

NASA Astrophysics Data System (ADS)

Kim, Jiwon; Lim, Jae-Hong; Myung, Nosang V.

2018-01-01

BixSb2-xTey films with controlled compositions were synthesized by a simple and cost-effective electrodeposition technique followed by post-annealing, for thermoelectric applications. Tailoring the chemical composition of ternary BixSb2-xTey materials is critical to adjust the carrier concentration and carrier type, which are crucial to determine their thermoelectric performance. Herein, the composition of electrodeposited BixSb2-xTey film was simply tailored by controlling the [Sb]/[Bi] ratio in the electrolytes while maintaining their dense and uniform morphology. Crystallographic properties of the BixSb2-xTey films, such as crystallinity and grain size changes, were confirmed by X-ray diffraction. Room-temperature measurements of electrical conductivity, Hall mobility, and carrier concentration revealed that the substitution of Bi with Sb decreased the carrier concentration, and increased the mobility. The Seebeck coefficient of the ternary BixSb2-xTey films transitioned between p- and n-type characteristics with an increase in the Bi content. Moreover, the mobility-dependent electrical conductivity of the Bi10Sb30Te60 film resulted in a high Seebeck coefficient owing to decreased carrier concentration of the film, leading to a power factor (PF) of ∼490 μW/m K2. This is more than 10 times higher than the PF values of binary nanocrystalline Sb2Te3 films.

Effect of substrate porosity on photoluminescence properties of ZnS films prepared on porous Si substrates by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Wang, Cai-Feng; Li, Qing-Shan; Zhang, Li-Chun; Lv, Lei; Qi, Hong-Xia

2007-05-01

ZnS films were deposited on porous Si (PS) substrates with different porosities by pulsed laser deposition. The photoluminescence spectra of the samples were measured to study the effect of substrate porosity on luminescence properties of ZnS/porous Si composites. After deposition of ZnS films, the red photoluminescence peak of porous Si shows a slight blueshift compared with as-prepared porous Si samples. With an increase of the porosity, a green emission at about 550 nm was observed which may be ascribed to the defect-center luminescence of ZnS films, and the photoluminescence of ZnS/porous Si composites is very close to white light. Good crystal structures of the samples were observed by x-ray diffraction, showing that ZnS films were grown in preferred orientation. Due to the roughness of porous Si surface, some cracks appear in ZnS films, which could be seen from scanning electron microscope images.

Effect Of Chromium Underlayer On The Properties Of Nano-Crystalline Diamond Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garratt, Elias; AlFaify, Salem; Yoshitake, T.

2013-01-11

This paper investigated the effect of chromium underlayer on the structure, microstructure and composition of the nano-crystalline diamond films. Nano-crystalline diamond thin films were deposited at high temperature in microwave-induced plasma diluted with nitrogen, on silicon substrate with a thin film of chromium as an underlayer. The composition, structure and microstructure of the deposited layers were analyzed using non-Rutherford Backscattering Spectrometry, Raman Spectroscopy, Near-Edge X-Ray Absorption Fine Structure, X-ray Diffraction and Atomic Force Microscopy. Nanoindentation studies showed that the films deposited on chromium underlayer have higher hardness values compared to those deposited on silicon without an underlayer. Diamond and graphiticmore » phases of the films evaluated by x-ray and optical spectroscopic analysis determined consistency between sp2 and sp3 phases of carbon in chromium sample to that of diamond grown on silicon. Diffusion of chromium was observed using ion beam analysis which was correlated with the formation of chromium complexes by x-ray diffraction.« less

Processing and property evaluation of tungsten-based mixed oxides for photovoltaics and optoelectronics

NASA Astrophysics Data System (ADS)

Vargas, Mirella

Tungsten Oxide (WO3) films and low-dimensional structures have proven to be promising candidates in the fields of photonics and electronics. WO3 is a well-established n-type semiconductor characterized by unique electrochromic behavior, an ideal optical band gap that permits transparency over a wide spectral range, and high chemical integrity. The plethora of diverse properties endow WO3 to be highly effective in applications related to electrochromism, gas sensing, and deriving economical energy. Compared to the bulk films, a materials system involving WO3 and a related species (elements or metal oxides) offer the opportunity to tailor the electrochromic response, and an overall enhancement of the physio-chemical and optical properties. In the present case, WO3 and TiO2 composite films have been fabricated by reactive magnetron sputtering employing W/Ti alloy targets, and individual W and Ti targets for co-sputtering. Composite WO3-TiO2 films were fabricated with variable chemical composition and the effect of variable bulk chemistry on film structure, surface/interface chemistry and chemical valence state of the W and Ti cations was investigated in detail. The process-property relationships between composition and physical properties for the films deposited by using W/Ti alloy targets of variable Ti content are associated with decreases in the deposition rate of the WO3-TiO2 films due to the lower sputter yield of the strongly bonded TiO2 formed on the target surface. Additionally, for the co-sputtered films using variable tungsten power, the optical properties demonstrate unique optical modulation. The changes associated with the physical color of the films demonstrate the potential to tailor the optical behavior for the design and fabrication of multilayer photovoltaic and catalytic devices. The process-structure-property correlation derived in this work will provide a road-map to optimize and produce W-Ti-O thin films with desired properties for a given technological application.

The behavior of MC3T3-E1 cells on chitosan/poly-L-lysine composite films: effect of nanotopography, surface chemistry, and wettability.

PubMed

Zheng, Zhenhuan; Zhang, Ling; Kong, Lijun; Wang, Aijun; Gong, Yandao; Zhang, Xiufang

2009-05-01

In the present work, a series of composite films were produced from chitosan/poly-L-lysine blend solutions. The surface topography, chemistry, and wettability of composite films were characterized by atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and contact angle assay, respectively. For all composite films, blending with poly-L-lysine induced changes in surface chemistry and wettability. Interestingly, it was also found that increasing poly-L-lysine weight fraction in blend solutions could result in different nanoscaled surface topographic features, which displayed particle-, granule-, or fiber-dominant morphologies. MC3T3-E1 osteoblast-like cells were cultured on all composite films to evaluate the effects of surface nanotopography, chemistry, and wettability on cell behavior. The observations indicated that MC3T3-E1 cell behavior was affected by surface topography, chemistry, and wettability simultaneously and that cells showed strong responses to surface topography. On fiber-dominant surface, cells fully spread with obvious cytoskeleton organization and exhibited significantly higher level of adhesion and proliferation compared with particle- or granule-dominant surfaces. Furthermore, fiber-dominant surface also induced greater expression of mature osteogenic marker osteocalcin and higher mineralization based on RT-PCR and von Kossa staining. The results suggest that topographic modification of chitosan substratum at the nanoscale may be exploited in regulating cell behavior for its applications in tissue engineering.

The Effect of Cu:Ag Atomic Ratio on the Properties of Sputtered Cu–Ag Alloy Thin Films

PubMed Central

Hsieh, Janghsing; Hung, Shunyang

2016-01-01

Cu–Ag thin films with various atomic ratios were prepared using a co-sputtering technique, followed by rapid thermal annealing at various temperatures. The films’ structural, mechanical, and electrical properties were then characterized using X-ray diffractometry (XRD), atomic force microscopy (AFM), FESEM, nano-indentation, and TEM as functions of compositions and annealing conditions. In the as-deposited condition, the structure of these films transformed from a one-phase to a dual-phase state, and the resistivity shows a twin-peak pattern, which can be explained in part by Nordheim’s Rule and the miscibility gap of Cu–Ag alloy. After being annealed, the films’ resistivity followed the mixture rule in general, mainly due to the formation of a dual-phase structure containing Ag-rich and Cu-rich phases. The surface morphology and structure also varied as compositions and annealing conditions changed. The recrystallization of these films varied depending on Ag–Cu compositions. The annealed films composed of 40 at % to 60 at % Cu had higher hardness and lower roughness than those with other compositions. Particularly, the Cu50Ag50 film had the highest hardness after being annealed. From the dissolution testing, it was found that the Cu-ion concentration was about 40 times higher than that of Ag. The galvanic effect and over-saturated state could be the cause of the accelerated Cu dissolution and the reduced dissolution of the Ag. PMID:28774033

Controllable degradation of medical magnesium by electrodeposited composite films of mussel adhesive protein (Mefp-1) and chitosan.

PubMed

Jiang, Ping-Li; Hou, Rui-Qing; Chen, Cheng-Dong; Sun, Lan; Dong, Shi-Gang; Pan, Jin-Shan; Lin, Chang-Jian

2016-09-15

To control the degradation rate of medical magnesium in body fluid environment, biocompatible films composed of Mussel Adhesive Protein (Mefp-1) and chitosan were electrodeposited on magnesium surface in cathodic constant current mode. The compositions and structures of the films were characterized by atomic force microscope (AFM), scanning electron microscope (SEM) and infrared reflection absorption spectroscopy (IRAS). And the corrosion protection performance was investigated using electrochemical measurements and immersion tests in simulated body fluid (Hanks' solution). The results revealed that Mefp-1 and chitosan successfully adhered on the magnesium surface and formed a protective film. Compared with either single Mefp-1 or single chitosan film, the composite film of chitosan/Mefp-1/chitosan (CPC (chitosan/Mefp-1/chitosan)) exhibited lower corrosion current density, higher polarization resistance and more homogenous corrosion morphology and thus was able to effectively control the degradation rate of magnesium in simulated body environment. In addition, the active attachment and spreading of MC3T3-E1 cells on the CPC film coated magnesium indicated that the CPC film was significantly able to improve the biocompatibility of the medical magnesium. Copyright © 2016 Elsevier Inc. All rights reserved.

Gelatin-hydroxypropyl methylcellulose water-in-water emulsions as a new bio-based packaging material.

PubMed

Esteghlal, Sara; Niakosari, Mehrdad; Hosseini, Seyed Mohammad Hashem; Mesbahi, Gholam Reza; Yousefi, Gholam Hossein

2016-05-01

Gelatin and hydroxypropyl methylcellulose (HPMC) are two incompatible and immiscible biopolymers which cannot form homogeneous composite films using usual methods. In this study, to prevent phase separation, gelatin-HPMC water-in-water (W/W) emulsion was utilized to from transparent composite films by entrapment the HPMC dispersed droplets in gelatin continuous network. The physicochemical and mechanical properties of emulsion-based films containing different amounts (5-30%) of dispersed phase were determined and compared with those of individual polymer-based films. Incorporating HPMC into W/W emulsion-based films had no significant effect on the tensile strength. The flexibility of composite films decreased at HPMC concentrations below 20%. The depletion layer at the droplets interface reduced the diffusion of water vapor molecules because of its hydrophobic nature, so the water vapor permeability remained constant. Increasing the HPMC content in the emulsion films increased the swelling and decreased the transparency. The entrapment of HPMC in continuous gelatin phase decreased its solubility. Therefore, W/W emulsions are capable of holding two incompatible polymers alongside each other within a homogeneous film network without weakening the physical properties. Copyright © 2016 Elsevier B.V. All rights reserved.

Films based on neutralized chitosan citrate as innovative composition for cosmetic application.

PubMed

Libio, Illen C; Demori, Renan; Ferrão, Marco F; Lionzo, Maria I Z; da Silveira, Nádya P

2016-10-01

In this work, citrate and acetate buffers, were investigated as neutralizers to chitosan salts in order to provide biocompatible and stable films. To choose the appropriate film composition for this study, neutralized chitosan citrate and acetate films, with and without the plasticizer glycerol, were prepared and characterized by thickness, moisture content, degree of swelling, total soluble matter in acid medium, simultaneous thermal analysis and differential scanning calorimetry. Chitosan films neutralized in citrate buffer showed greater physical integrity resulted from greater thicknesses, lower moisture absorbance, lower tendency to solubility in the acid medium, and better swelling capacities. According to thermal analyses, these films had higher interaction with water which is considered an important feature for cosmetic application. Since the composition prepared in citrate buffer without glycerol was considered to present better physical integrity, it was applied to investigate hyaluronic acid release in a skin model. Skins treated with those films, with or without hyaluronic acid, show stratum corneum desquamation and hydration within 10min. The results suggest that the neutralized chitosan citrate film prepared without glycerol promotes a cosmetic effect for skin exfoliation in the presence or absence of hyaluronic acid. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of various plasticizers and nanoclays on the mechanical properties of red algae film.

PubMed

Jang, S A; Shin, Y J; Seo, Y B; Song, K B

2011-04-01

To manufacture red algae (RA) film, we used various plasticizers such as glycerol, sorbitol, sucrose, fructose, and polypropylene glycol (PPG), and then determined the mechanical properties of the RA films. The tensile strength (TS), elongation at break (E), and water vapor permeability (WVP) of the films containing various plasticizers ranged between 0.43 to 9.10 MPa, 10.93% to 47.17%, and 1.28 to 1.42 ng m/m2sPa, respectively. RA films containing fructose as a plasticizer had the best mechanical properties of all the films evaluated. Incorporation of nanoclay (Cloisite Na+ and 30B) improved the mechanical properties of the films. RA film with 3% Cloisite Na+ had a TS of 10.89, while RA film with 30B had a TS of 10.85 MPa; these films also had better E and WVP values than the other RA films evaluated. These results suggest that RA/nanoclay composite films are suitable for use as food packaging materials.   Edible RE/nanoclay composite films prepared in the present investigation can be applied in food packaging.

Effect of γ irradiation on poly(vinyl alcohol) and bacterial cellulose composites used as packaging materials

NASA Astrophysics Data System (ADS)

Stoica-Guzun, Anicuta; Stroescu, Marta; Jipa, Iuliana; Dobre, Loredana; Zaharescu, Traian

2013-03-01

The aim of this paper is to present the influence of bacterial cellulose microfibrils and γ-radiation dose on poly(vinyl alcohol) (PVA)-bacterial cellulose (BC) composites. Two composite materials were obtained: the first one from PVA aqueous solution 4% and 5% wet bacterial cellulose and the second from the same PVA solution and 10% wet bacterial cellulose. In terms of PVA/dry BC ratios (w/w) for these films the ratios are 1/0.025 and 1/0.050. The obtained composite materials were characterized by infrared spectroscopy with Fourier transform (FT-IR) and UV-vis spectroscopy in order to evaluate the irradiation effect on their stability. The swelling behavior of the polymeric composites was also studied. The composite materials were compared with a film of pure PVA and a dry BC membrane.

Reverse-osmosis membranes by plasma polymerization

NASA Technical Reports Server (NTRS)

Hollahan, J. R.; Wydeven, T.

1972-01-01

Thin allyl amine polymer films were developed using plasma polymerization. Resulting dry composite membranes effectively reject sodium chloride during reverse osmosis. Films are 98% sodium chloride rejective, and 46% urea rejective.

Composition-ratio influence on resistive switching behavior of solution-processed InGaZnO-based thin-film.

PubMed

Hwang, Yeong-Hyeon; Hwang, Inchan; Cho, Won-Ju

2014-11-01

The influence of composition ratio on the bipolar resistive switching behavior of resistive switching memory devices based on amorphous indium-gallium-zinc-oxide (a-IGZO) using the spin-coating process was investigated. To study the stoichiometric effects of the a-IGZO films on device characteristics, four devices with In/Ga/Zn stoichiometries of 1:1:1, 3:1:1, 1:3:1, and 1:1:3 were fabricated and characterized. The 3:1:1 film showed an ohmic behavior and the 1:1:3 film showed a rectifying switching behavior. The current-voltage characteristics of the a-IGZO films with stoichiometries of 1:1:1 and 1:3:1, however, showed a bipolar resistive memory switching behavior. We found that the three-fold increase in the gallium content ratio reduces the reset voltage from -0.9 to - 0.4 V and enhances the current ratio of high to low resistive states from 0.7 x 10(1) to 3 x 10(1). Our results show that the increase in the Ga composition ratio in the a-IGZO-based ReRAM cells effectively improves the device performance and reliability by increasing the initial defect density in the a-IGZO films.

Fabrication and properties of polyvinyl alcohol/starch blend films: Effect of composition and humidity.

PubMed

Tian, Huafeng; Yan, Jiaan; Rajulu, A Varada; Xiang, Aimin; Luo, Xiaogang

2017-03-01

In this work, starch/polyvinyl alcohol (PVA) blend films with different compositions were prepared by melt processing. The effect of the composition and relative humidity (RH) on the structure and properties of the resulting blends were investigated. OH groups on starch and PVA formed hydrogen bonding interactions, which could improve the compatibility of the two components. With the increase of starch, the degree of crystallinity of PVA component decreased. The fracture surface of the blend films exhibited rough surface, suggesting the tough fracture. With the increase of starch, the water uptake at equilibrium decreased. With the increase of RH, the water uptake at equilibrium of the resulting blends increased. The tensile strength, elongation at break and Young's modulus decreased with increasing content of starch. However, at 50% starch content, the flexibility of the blend films was still high, with the elongation at break more than 1000% and tensile strength of 9MPa, which was superior to the commonly LDPE package films. The tensile strength and Young's modulus decreased with the increase of RH, while the elongation at break was enhanced dramatically, indicating the improved flexibility. Therefore, these kinds of blend films exhibited wide application potentials as packaging materials. Copyright © 2016 Elsevier B.V. All rights reserved.

Incorporation of Keplerate-type Mo-O based macroanions into Zn2Al-LDH results in the formation of all-inorganic composite films with remarkable third-order optical nonlinearity.

PubMed

Ren, Haizhou; Shehzad, Farooq Khurum; Zhou, Yunshan; Zhang, Lijuan; Iqbal, Arshad; Long, Yi

2018-05-01

Herein, new all-inorganic transparent composite films with the formula (Zn2Al-LDH/{Mo132-Ac})n have been fabricated by a layer-by-layer method using the exfoliated Zn2Al-LDH monolayer nanosheets and Keplerate-type macroanion {Mo132-Ac}. They were characterized by UV-vis absorption spectroscopy, SEM, AFM, and XPS techniques. The Z-scan measurements, which were conducted under laser irradiation at a wavelength of 532 nm, a pulse width of 6 ns, a repetition rate of 10 Hz, and the light intensity at a focus E0 of 10 μJ, revealed that all the films had notable saturated absorption and self-defocusing effect with a large third-order optical nonlinear susceptibility χ(3). With an increase in the number of layers (i.e., n) corresponding to the increase in the thickness of the films, the third-order nonlinear absorption β and refractive effects of the films were improved (i.e., the χ(3) value was up to 1.99 × 10-11 esu when n = 24); this implied that the NLO responses could be modified by fine-tuning the thickness of the composite films to meet the demands of different devices.

In situ Fenton reagent generated from TiO2/Cu2O composite film: a new way to utilize TiO2 under visible light irradiation.

PubMed

Zhang, Yong-Gang; Ma, Li-Li; Li, Jia-Lin; Yu, Ying

2007-09-01

TiO2/Cu2O composite is prepared by a simple electrochemical method and coated on glass matrix through a spraying method. The obtained composite is characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of TiO2/Cu2O composite films with different ratio of TiO2 and Cu2O on photodegradation of the dye methylene blue under visible light is investigated in detail. It is found that the photocatalytic activity of TiO2/Cu2O composite film with the presence of FeSO4 and EDTA is much higher than that for the similar system with only TiO2 and Cu2O film respectively. Without the presence of FeSO4 and EDTA, there is no degradation for methylene blue. The exploration of the optimized parameters for the degradation of methylene blue by using TiO2/Cu2O composite film as catalyst under visible light was also carried out. The most significant factor is the amount of Ti02 in the composite, and the second significant factor is the concentration of FeSO4. During the degradation of methylene blue under visible light, TiO2/Cu2O composite film generates H202, and Fenton regent is formed with Fe2+ and EDTA, which is detected in this study. The mechanism for the great improvement of photocatalytic activity of TiO2/Cu2O composite film under visible light is proposed by the valence band theory. Electrons excitated from TiO2/Cu2O composite under visible light are transferred from the conduction band of Cu2O to that of Ti02. The formed intermediate state of Ti 3+ ion is observed by X-ray photoelectron spectroscopy (XPS) on the TiO/Cu2O composite film. Additionally, the accumulated electrons in the conduction band of TiO2 are transferred to oxygen on the TiO2 surface for the formation of O2- or O2(2-), which combines with H+ to form H2O2. The evolved H202 with FeSO4 and EDTA forms Fenton reagentto degrade methylene blue. Compared to the traditional Fenton reagent, this new kind of in situ Fenton reagent generated from TiO2/Cu2O composite film does not need to supply H202. It is expected to be easily recycled, which may reduce second pollution and the cost of wastewater treatment. Moreover, this TiO/Cu2O composite film with FeSO4 and EDTA provides a new way to take advantage of TiO2 under visible light.

Impact of composition and crystallization behavior of atomic layer deposited strontium titanate films on the resistive switching of Pt/STO/TiN devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aslam, N.; Rodenbücher, C.; Szot, K.

2014-08-14

The resistive switching (RS) properties of strontium titanate (Sr{sub 1+x}Ti{sub 1+y}O{sub 3+(x+2y)}, STO) based metal-oxide-metal structures prepared from industrial compatible processes have been investigated focusing on the effects of composition, microstructure, and device size. Metastable perovskite STO films were prepared on Pt-coated Si substrates utilizing plasma-assisted atomic layer deposition (ALD) from cyclopentadienyl-based metal precursors and oxygen plasma at 350 °C, and a subsequent annealing at 600 °C in nitrogen. Films of 15 nm and 12 nm thickness with three different compositions [Sr]/([Sr] + [Ti]) of 0.57 (Sr-rich STO), 0.50 (stoichiometric STO), and 0.46 (Ti-rich STO) were integrated into Pt/STO/TiN crossbar structures with sizes ranging from 100 μm{supmore » 2} to 0.01 μm{sup 2}. Nano-structural characterizations revealed a clear effect of the composition of the as-deposited STO films on their crystallization behavior and thus on the final microstructures. Local current maps obtained by local-conductivity atomic force microscopy were in good agreement with local changes of the films' microstructures. Correspondingly, also the initial leakage currents of the Pt/STO/TiN devices were affected by the STO compositions and by the films' microstructures. An electroforming process set the Pt/STO/TiN devices into the ON-state, while the forming voltage decreased with increasing initial leakage current. After a RESET process under opposite voltage has been performed, the Pt/STO/TiN devices showed a stable bipolar RS behavior with non-linear current-voltage characteristics for the high (HRS) and the low (LRS) resistance states. The obtained switching polarity and nearly area independent LRS values agree with a filamentary character of the RS behavior according to the valence change mechanism. The devices of 0.01 μm{sup 2} size with a 12 nm polycrystalline stoichiometric STO film were switched at a current compliance of 50 μA with voltages of about ±1.0 V between resistance states of about 40 kΩ (LRS) and 1 MΩ (HRS). After identification of the influences of the films' microstructures, i.e., grain boundaries and small cracks, the remaining RS properties could be ascribed to the effect of the [Sr]/([Sr] + [Ti]) composition of the ALD STO thin films.« less

The effect of stoichiometry on Cu-Zn ordering kinetics in Cu2ZnSnS4 thin films

NASA Astrophysics Data System (ADS)

Rudisch, Katharina; Davydova, Alexandra; Platzer-Björkman, Charlotte; Scragg, Jonathan

2018-04-01

Cu-Zn disorder in Cu2ZnSnS4 (CZTS) may be responsible for the large open circuit voltage deficit in CZTS based solar cells. In this study, it was investigated how composition-dependent defect complexes influence the order-disorder transition. A combinatorial CZTS thin film sample was produced with a cation composition gradient across the sample area. The graded sample was exposed to various temperature treatments and the degree of order was analyzed with resonant Raman spectroscopy for various compositions ranging from E- and A-type to B-, F-, and C-type CZTS. We observe that the composition has no influence on the critical temperature of the order-disorder transition, but strongly affects the activation energy. Reduced activation energy is achieved with compositions with Cu/Sn > 2 or Cu/Sn < 1.8 suggesting an acceleration of the cation ordering in the presence of vacancies or interstitials. This is rationalized with reference to the effect of point defects on exchange mechanisms. The implications for reducing disorder in CZTS thin films are discussed in light of the new findings.

Tunable thermal conductivity via domain structure engineering in ferroelectric thin films: A phase-field simulation

DOE PAGES

Wang, Jian -Jun; Wang, Yi; Ihlefeld, Jon F.; ...

2016-04-06

Effective thermal conductivity as a function of domain structure is studied by solving the heat conduction equation using a spectral iterative perturbation algorithm in materials with inhomogeneous thermal conductivity distribution. Using this proposed algorithm, the experimentally measured effective thermal conductivities of domain-engineered {001} p-BiFeO 3 thin films are quantitatively reproduced. In conjunction with two other testing examples, this proposed algorithm is proven to be an efficient tool for interpreting the relationship between the effective thermal conductivity and micro-/domain-structures. By combining this algorithm with the phase-field model of ferroelectric thin films, the effective thermal conductivity for PbZr 1-xTi xO 3 filmsmore » under different composition, thickness, strain, and working conditions is predicted. It is shown that the chemical composition, misfit strain, film thickness, film orientation, and a Piezoresponse Force Microscopy tip can be used to engineer the domain structures and tune the effective thermal conductivity. Furthermore, we expect our findings will stimulate future theoretical, experimental and engineering efforts on developing devices based on the tunable effective thermal conductivity in ferroelectric nanostructures.« less

Tunable thermal conductivity via domain structure engineering in ferroelectric thin films: A phase-field simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jian -Jun; Wang, Yi; Ihlefeld, Jon F.

Effective thermal conductivity as a function of domain structure is studied by solving the heat conduction equation using a spectral iterative perturbation algorithm in materials with inhomogeneous thermal conductivity distribution. Using this proposed algorithm, the experimentally measured effective thermal conductivities of domain-engineered {001} p-BiFeO 3 thin films are quantitatively reproduced. In conjunction with two other testing examples, this proposed algorithm is proven to be an efficient tool for interpreting the relationship between the effective thermal conductivity and micro-/domain-structures. By combining this algorithm with the phase-field model of ferroelectric thin films, the effective thermal conductivity for PbZr 1-xTi xO 3 filmsmore » under different composition, thickness, strain, and working conditions is predicted. It is shown that the chemical composition, misfit strain, film thickness, film orientation, and a Piezoresponse Force Microscopy tip can be used to engineer the domain structures and tune the effective thermal conductivity. Furthermore, we expect our findings will stimulate future theoretical, experimental and engineering efforts on developing devices based on the tunable effective thermal conductivity in ferroelectric nanostructures.« less

Synthesis and Characterization of Protein-Conjugated Silver Nanoparticles/Silver Salt Loaded Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) Film for Prevention of Bacterial Infections and Potential Use in Bone Tissue Engineering Applications

NASA Astrophysics Data System (ADS)

Bakare, Rotimi Ayotunde

Failure of orthopedic implants due to bacterial infection has been a major concern in bone tissue engineering. To this end, we have formulated a potential orthopedic implant made of naturally occurring biodegradable polymer, i.e. poly (3-hydroxylbutyrate-co-3-hydroxylvalerate) (PHBV), modified with BSA conjugated silver nanoparticles and or silver chloride. Upon release of Ag NPs and or Ag+ in the implant region, can promote aseptic environment by inhibition of bacteria growth and also support/maintain bone cell adhesion, growth, and proliferation. For formulating nanoparticles loaded PHBV scaffold, we exploit specific interaction between bovine serum albumin (BSA) of BSA capped silver nanoparticles and collagen of collagen immobilized PHBV scaffold. Therefore, the first part of this study dealt with synthesis and characterization of collagen immobilized PHBV film for loading of BSA stabilized silver (Ag/BSA) nanoparticles. Two different approaches were used to immobilize collagen on macroporous PHBV film. First approach uses thermal radical copolymerization with 2-hydroxyethylmethacrylate (HEMA), while the second approach uses aminolysis to functionalize macroporous PHBV film. Using collagen crosslinker, type I collagen was covalently grafted to formulate collagen immobilized PHEMA-g-PHBV and collagen immobilized NH2-PHBV films, respectively. Spectroscopic (FTIR, XPS), physical (SEM), and thermal (TGA) techniques were used to characterize the functionalized PHBV films. The Ag/BSA nanoparticles were then loaded on collagen immobilized PHBV films and untreated PHBV films. The concentration of nanoparticles loaded on PHBV film was determined by atomic absorption spectrometry and fluorescence spectroscopy. The amount of nanoparticles loaded on collagen immobilized PHBV film was found to be significantly greater than that on untreated PHBV film. The amount of Ag/BSA nanoparticles loaded on collagen immobilized PHBV film was found to depend on the concentration of Ag/BSA nanoparticles solution used for loading and on the molecular weight of type I collagen used in collagen immobilization on PHBV film. At physiological pH, optimum amount of nanoparticles was retained on Type I collagen immobilized PHBV film because at pH 7.4, protonated amino groups of collagen immobilized PHBV film promote strong electrostatic interaction with the carboxylate anions of BSA stabilized silver nanoparticles. The second part of this study dealt with formulating AgCl/PHBV film that can potentially release silver ions for effective antimicrobial activity. In this study, we formulated AgCl/PHBV composite film by a salt exchange mechanism. Thermogravimetric analysis (TGA) was used to quantify the amount of NaCl present before and after salt exchange. The Na content in the pre-washed and partially washed NaCl/PHBV film was found to be 43.60% and 1.24% by mass, respectively. The AgCl/PBHV composite film was acid digested and assayed for Na+ and Ag+ content by using Atomic Absorption Spectrometry (AAS) and was found to be 2.15 and 10.25 ppm, respectively. XPS technique was used to characterize the surface elemental composition of the AgCl/PHBV composite film. The survey spectrum of AgCl/PHBV film showed emergence of Ag 3d and Cl 2s peaks compared to pure PHBV which was predominantly composed of C 1s and O 1s peaks. The release kinetics of silver ions from AgCl/PHBV composite film showed an initial burst of about 1.5 ppm of silver ions during the first day of desorption followed by a gradual release of silver ions at an average rate of 0.3 ppm per day during the span of two weeks studied. Ag/BSA nanoparticles loaded collagen immobilized PHBV films and AgCl/PHBV composite films were tested for antibacterial efficacy against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Colony forming unit and optical density measurements of Ag/BSA nanoparticles loaded collagen immobilized PHBV films showed broad antimicrobial activity at low Ag/BSA nanoparticles concentration (0.19and 0.31 microg) compared to commercially available gentamicin and sulfamethoxazole/trimethoprim which showed sometimes selective antimicrobial activity and antimicrobial activity at high concentration (10 microg and 23.75/1.25 microg/disc). Additionally, a clear zone of inhibition around AgCl/PHBV composite film was noticed on a modified Kirby-Bauer disk diffusion assay. Optical density results and colony forming unit measurements showed that AgCl/PHBV composite film exhibit broad bactericidal activity. Next, we evaluated the cytotoxicity of Ag/BSA nanoparticles loaded collagen immobilized PHBV films and AgCl/PHBV composite films towards MC3T3-E1 cells at the same concentration both films showed broad antimicrobial activity. By using MTT assay, we established that Ag/BSA nanoparticles loaded collagen immobilized PHBV film showed minimal, if any, cytotoxic effect towards MC3T3-E1 cells while AgCl/PHBV composite film showed significant cytotoxic effect compared to tissue culture polystyrene. Our research findings provide several formulations for preparation of scaffold, if properly tuned; it can be used as a potential biocompatible and biodegradable scaffold for the prevention of bacterial infections and promotion of cell attachment and proliferation in bone tissue engineering applications.

Effect of ZnO buffer layer on phase transition properties of vanadium dioxide thin films

NASA Astrophysics Data System (ADS)

Zhu, Huiqun; Li, Lekang; Li, Chunbo

2016-03-01

VO2 thin films were prepared on ZnO buffer layers by DC magnetron sputtering at room temperature using vanadium target and post annealing at 400 °C. The ZnO buffer layers with different thickness deposited on glass substrates by magnetron sputtering have a high visible and near infrared optical transmittance. The electrical resistivity and the phase transition properties of the VO2/ZnO composite thin films in terms of temperature were investigated. The results showed that the resistivity variation of VO2 thin film with ZnO buffer layer deposited for 35 min was 16 KΩ-cm. The VO2/ZnO composite thin films exhibit a reversible semiconductor-metal phase transition at 48 °C.

Effect of POLYURETHANE/NANO-SiO2 Composites Coating on Thermo-Mechanical Properties of Polyethylene Film

NASA Astrophysics Data System (ADS)

Ching, Yern Chee; Yaacob, Iskandar Idris

2011-06-01

Polyethylene (PE) film was coated with polyurethane/nanosilica composite layer using rod Mayer process. The polyurethane/nanosilica system was prepared by dispersing nanosilica powder into solvent borne polyurethane (PU) binder under vigorous stirring. The silica nanoparticle used has an average diameter of 16 nm, and their weight fraction were varied from 0 % to 14 %. Two different thicknesses of the PU/nanosilica coating layer were fabricated which were about 4 μm and 8 μm. The structure and thermal mechanical features of the nanocomposite coated PE film were characterized by scanning electron microscope (SEM), dynamic mechanical analyzer (DMA), thermogravimetric analyzer (TGA) as well as tensile tests. The results showed that thin layer coating of the PU/nanosilica composite reduced tensile strength of PE substrate slightly. However, the nanocomposite coating of up to 8 μm reduced the elongation % of PE substrate significantly. PU/nanosilica composite coating layer increased the tensile modulus and stiffness of PE substrate. There was no influence of the PU/nanosilica composite coating to the thermal degradation rate of PE film.

Structural, chemical and electrical characterisation of conductive graphene-polymer composite films

NASA Astrophysics Data System (ADS)

Brennan, Barry; Spencer, Steve J.; Belsey, Natalie A.; Faris, Tsegie; Cronin, Harry; Silva, S. Ravi P.; Sainsbury, Toby; Gilmore, Ian S.; Stoeva, Zlatka; Pollard, Andrew J.

2017-05-01

Graphene poly-acrylic and PEDOT:PSS nanocomposite films were produced using two alternative commercial graphene powders to explore how the graphene flake dimensions and chemical composition affected the electrical performance of the film. A range of analytical techniques, including scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), were employed to systematically analyse the initial graphene materials as well as the nanocomposite films. Electrical measurements indicated that the sheet resistance of the films was affected by the properties of the graphene flakes used. To further explore the composition of the films, ToF-SIMS mapping was employed and provided a direct means to elucidate the nature of the graphene dispersion in the films and to correlate this with the electrical analysis. These results reveal important implications for how the dispersion of the graphene material in films produced from printable inks can be affected by the type of graphene powder used and the corresponding effect on electrical performance of the nanocomposites. This work provides direct evidence for how accurate and comparable characterisation of the graphene material is required for real-world graphene materials to develop graphene enabled films and proposes a measurement protocol for comparing graphene materials that can be used for international standardisation.

Application of nano-TiO2/LDPE composite film on photocatalytic oxidation degradation of dichloromethane.

PubMed

Suwannahong, Kowit; Liengcharernsit, Winai; Sanongraj, Wipada; Kruenate, Jittiporn

2012-09-01

This study focused on the photocatalytic destruction of dichloromethane (DCM) in indoor air using the nano-TiO2/LDPE composite film as an economical photocatalyst. The nano-TiO2 was dispersed in a polyethylene matrix to form composite film. The photocatalytic activity of the nano-TiO2/LDPE composite films was evaluated through the degradation of dichloromethane(DCM) under UV-C irradiance at specific wavelength of 254 nm. The percentage of nano-TiO2 contents varied from 0, 5, and 10% (wt cat./wt LDPE composite film). The results derived from the kinetic model revealed that the photocatalytic rates of 5 and 10 wt.% nano-TiO2/ LDPE composite films follow the first order reaction while the rate of the film without TiO2 followed the zero order reaction. At low concentration of DCM, the rate of photocatalytic degradation of the DCM was slower than that at high DCM concentration. The 10 wt.% of TiO2 content of the nano-TiO2/LDPE composite film yielded the highest degradation efficiency of 78%, followed by the removal efficiency of 55% for the 5 wt.% of TiO2 content of the nano-TiO2/LDPE composite film. In contrast with the composite film containing nano-TiO2, the LDPE film without adding nano-TiO2 expressed the degradation efficiency of 28%.

Atomic and Molecular Layer Deposition for Enhanced Lithium Ion Battery Electrodes and Development of Conductive Metal Oxide/Carbon Composites

NASA Astrophysics Data System (ADS)

Travis, Jonathan

The performance and safety of lithium-ion batteries (LIBs) are dependent on interfacial processes at the positive and negative electrodes. For example, the surface layers that form on cathodes and anodes are known to affect the kinetics and capacity of LIBs. Interfacial reactions between the electrolyte and the electrodes are also known to initiate electrolyte combustion during thermal runaway events that compromise battery safety. Atomic layer deposition (ALD) and molecular layer deposition (MLD) are thin film deposition techniques based on sequential, self-limiting surface reactions. ALD and MLD can deposit ultrathin and conformal films on high aspect ratio and porous substrates such as composite particulate electrodes in lithium-ion batteries. The effects of electrode surface modification via ALD and MLD are studied using a variety of techniques. It was found that sub-nm thick coatings of Al2O 3 deposited via ALD have beneficial effects on the stability of LIB anodes and cathodes. These same Al2O3 ALD films were found to improve the safety of graphite based anodes through prevention of exothermic solid electrolyte interface (SEI) degradation at elevated temperatures. Ultrathin and conformal metal alkoxide polymer films known as "metalcones" were grown utilizing MLD techniques with trimethylaluminum (TMA) or titanium tetrachloride (TiCl4) and organic diols or triols, such as ethylene glycol (EG), glycerol (GL) or hydroquinone (HQ), as the reactants. Pyrolysis of these metalcone films under inert gas conditions led to the development of conductive metal oxide/carbon composites. The composites were found to contain sp2 carbon using micro-Raman spectroscopy in the pyrolyzed films with pyrolysis temperatures ≥ 600°C. Four point probe measurements demonstrated that the graphitic sp2 carbon domains in the metalcone films grown using GL and HQ led to significant conductivity. The pyrolysis of conformal MLD films to obtain conductive metal oxide/carbon composite films is presented as a method for enabling non-conductive, but possibly electrochemically active materials, to be used for electrochemical applications.

Magnetic Fe-Co films electroplated in a deep-eutectic-solvent-based plating bath

NASA Astrophysics Data System (ADS)

Yanai, T.; Shiraishi, K.; Watanabe, Y.; Ohgai, T.; Nakano, M.; Suzuki, K.; Fukunaga, H.

2015-05-01

We fabricated Fe-Co films from a deep eutectic solvent (DES)-based plating bath and investigated magnetic properties of the plated films. The plating baths were obtained by stirring the mixture of choline chloride, ethylene glycol, FeCl2.4H2O, and CoCl2.6H2O. The composition of the plated films depended on the amount of FeCl2.4H2O in the plating bath, and Fe content of the films was varied from 0 to 100 at. %. Depending on the Fe content, the saturation magnetization and the coercivity of the films varied. The Fe76Co24 film shows high saturation magnetization and smooth surface, and the change in the saturation magnetization shows good agreement with the expected change by the Slater-Pauling curve. High current efficiency (>90%) could be obtained in the wide film composition. From these results, we concluded that the DES-based plating bath is one of effective baths for the Fe-Co films with high current efficiency.

Optical and dielectric properties of poly(vinyl-alcohol) - Cobalt oxide nanocomposite film

NASA Astrophysics Data System (ADS)

Das, Amit Kumar; Tripathi, Himadri Sekhar; Meikap, Ajit Kumar

2018-04-01

Highly crystalline cobalt oxide (Co3O4) have been synthesized via calcination method. The crystallite size of the nanoparticles is 28.5 nm. Two direct band gap of Co3O4 is observed. The temperature dependent dielectric spectroscopy of PVA-Co3O4 composite film shows ferroelectric behavior. The dielectric constant of the composite film is almost 2.5 times compare to pure PVA at a 1kHz frequency and room temperature. From the Nyquist plot grain and grain boundary effects are identified.

Polyaniline/Carbon nanotube Electrochromic Films: Electrochemical Polymerization and characterization

NASA Astrophysics Data System (ADS)

Li, Xiao-Xia; Zhao, Liang; Ma, De-Yue; Zeng, Yu-Run

2018-02-01

Polyaniline/Carbon nanotube (PANI/CNT) composite films doped with dodecyl-benzene sulfonic acid were synthesized by cyclic voltammetry on an ITO-coated glass substrate. FTIR, XRD and electrochemical analyzer were used to characterize the micro-morphology, chemical structure, crystallinity and electrochromic behavior of the films, respectively. The effect of CNT content on the properties of the films was investigated. Results show that the introducing CNTs make aniline polymerize easier than before. Within a range, the conductivity and crystallinity of PANI/CNT composites improves with CNT content increasing. The electrochromic device made from the PAN/CNT film with a CNT content of 2.5wt% presents a reflectance contrast of 38.8%, a mean response time of 2.3s and a coloration efficiency of 386.4cm2/C at 540nm. The PAN/CNT film shows better electrochromic behaviors due to some interaction between CNTs and the PANI backbones than PANI film.

Flexible n-type thermoelectric composite films with enhanced performance through interface engineering and post-treatment.

PubMed

An, Hyeunhwan; Karas, Dale; Kim, Byung-Wook; Trabia, Sarah; Moon, Jaeyun

2018-07-06

Flexible thermoelectric (TE) materials, which are devices that convert thermal gradients to electrical energy, have attracted interest for practical energy-harvesting/recovery applications. However, as compared with p-type materials, the progress on the development of n-type TE flexible materials has been slow due to difficulties involved in n-type doping techniques. This study used high mobility carbon nanotubes (CNTs) to a uniformly mixed hybrid-composite, resulting in an enhanced power factor by increasing electrical conductivity. The energy filtering effect and stoichiometric composition of the material used, bismuth telluride (Bi 2 Te 3 ) correlated to a significant enhancement in TE performance, with a power factor of 225.9 μW m -1 K -2 at room temperature: a factor of 65 higher than as-fabricated composite film. This paper describes a simplified synthesis for the preparation of the composite film that eliminates time-intensive and cost-prohibitive processing, traditionally seen during extrusion and dicing inorganic manufacturing. The resulting post-annealed composite film consisting of Bi 2 Te 3 nanowire and CNTs demonstrate a promising candidate for material that can be used for an n-type TE device that has improved energy conversion efficiency.

Flexible n-type thermoelectric composite films with enhanced performance through interface engineering and post-treatment

NASA Astrophysics Data System (ADS)

An, Hyeunhwan; Karas, Dale; Kim, Byung-Wook; Trabia, Sarah; Moon, Jaeyun

2018-07-01

Flexible thermoelectric (TE) materials, which are devices that convert thermal gradients to electrical energy, have attracted interest for practical energy-harvesting/recovery applications. However, as compared with p-type materials, the progress on the development of n-type TE flexible materials has been slow due to difficulties involved in n-type doping techniques. This study used high mobility carbon nanotubes (CNTs) to a uniformly mixed hybrid-composite, resulting in an enhanced power factor by increasing electrical conductivity. The energy filtering effect and stoichiometric composition of the material used, bismuth telluride (Bi2Te3) correlated to a significant enhancement in TE performance, with a power factor of 225.9 μW m‑1K‑2 at room temperature: a factor of 65 higher than as-fabricated composite film. This paper describes a simplified synthesis for the preparation of the composite film that eliminates time-intensive and cost-prohibitive processing, traditionally seen during extrusion and dicing inorganic manufacturing. The resulting post-annealed composite film consisting of Bi2Te3 nanowire and CNTs demonstrate a promising candidate for material that can be used for an n-type TE device that has improved energy conversion efficiency.

Mechanical and Barrier Properties of Semi Refined Kappa Carrageenan-based Composite Edible Film and Its Application on Minimally Processed Chicken Breast Fillet

NASA Astrophysics Data System (ADS)

Praseptiangga, D.; Maimuni, B. H.; Manuhara, G. J.; Muhammad, D. R. A.

2018-03-01

Kappa-carrageenan (KC) is one of the most interesting biopolymers that is composed of a linear chain of sulfated galactans and extracted from red seaweed, Kappaphycus alvarezii. It shows good potential for development as a source of biodegradable or edible films. However, KC films do not have good water vapor barrier properties, as they are intrinsically hydrophilic. Palmitic acid (PA) as hydrophobic material was incorporated into semi-refined kappa-carrageenan (SRKC) edible films in order to improve water vapor barrier properties. In this study, composite films based on SRKC incorporating PA were prepared and their applications on minimally processed chicken breast fillet were evaluated. Composite SRKC-based films with varying concentrations of PA (5%, 10%, and 15% w/w) were obtained by a solvent casting method. Their mechanical and barrier properties were investigated. Results showed that the incorporation of PA in films caused an increase in thickness, but decrease in water vapor transmission rate (WVTR) as the concentration of PA increased (from 5% to 15% w/w). Composite SRKC-based edible film incorporating 15% w/w of PA presented better water vapor barrier properties as compared to other films with 5% and 10% w/w PA incorporation. Thus, formulation containing 15% w/w PA was used as a wrapping material for film application on minimally processed chicken breast fillet. The application results showed that the incorporation of PA in film caused an effect (p < 0.05) on preventing of weight loss significantly compare to control (non-wrapping), however it did not significantly (p >0.05) change the color of minimally processed chicken breast fillet.

Composite polymeric film and method for its use in installing a very-thin polymeric film in a device

DOEpatents

Duchane, D.V.; Barthell, B.L.

1982-04-26

A composite polymeric film and a method for its use in forming and installing a very thin (< 10 ..mu..m) polymeric film are disclosed. The composite film consists of a thin film layer and a backing layer. The backing layer is soluble in a solvent in which the thin film layer is not soluble. In accordance with the method, the composite film is installed in a device in the same position in which it is sought to finally emplace the thin film. The backing layer is then selectiely dissolved in the solvent to leave the insoluble thin film layer as an unbacked film. The method permits a very thin film to e successfully installed in devices where the fragility of the film would preclude handling and installation by conventional methods.

Composite polymeric film and method for its use in installing a very thin polymeric film in a device

DOEpatents

Duchane, David V.; Barthell, Barry L.

1984-01-01

A composite polymeric film and a method for its use in forming and installing a very thin (<10 .mu.m) polymeric film are disclosed. The composite film consists of a thin film layer and a backing layer. The backing layer is soluble in a solvent in which the thin film layer is not soluble. In accordance with the method, the composite film is installed in a device in the same position in which it is sought to finally emplace the thin film. The backing layer is then selectively dissolved in the solvent to leave the insoluble thin film layer as an unbacked film. The method permits a very thin film to be successfully installed in devices where the fragility of the film would preclude handling and installation by conventional methods.

Light diffusing films fabricated by strawberry-like PMMA/SiO₂ composite microspheres for LED application.

PubMed

Guo, Shuang; Zhou, Shuxue; Li, Huijing; You, Bo

2015-06-15

This paper presents a facile method to fabricate volumetric light diffusing films with high transmittance and haze simultaneously by mimicking the micro- and nanostructure of compound eyes. Strawberry-like polymethyl methacrylate/SiO2 composite microspheres were first prepared via the electrostatic attraction between positively charged PMMA spheres and negatively charged SiO2 nanoparticles, and further blended with polyacrylate latex to produce light diffusing coatings. A novel light diffusing film with hemispherical surface was built by casting the light diffusing coatings on optical-grade PET film. Effects of the sizes of PMMA spheres and SiO2 nanoparticles on the optical properties of light diffusing film were investigated by a haze meter and application on a LED lamp. The best result (transmittance 94.6% and haze 84.2%) was achieved for the strawberry-like composite microspheres based on 1 μm PMMA spheres and 50 nm SiO2 nanoparticles. The light-diffusing mechanism of the strawberry-like microspheres in the film was discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

Functionalizing CNTs for Making Epoxy/CNT Composites

NASA Technical Reports Server (NTRS)

Chen, Jian; Rajagopal, Ramasubramaniam

2009-01-01

Functionalization of carbon nanotubes (CNTs) with linear molecular side chains of polyphenylene ether (PPE) has been shown to be effective in solubilizing the CNTs in the solvent components of solutions that are cast to make epoxy/CNT composite films. (In the absence of solubilization, the CNTs tend to clump together instead of becoming dispersed in solution as needed to impart, to the films, the desired CNT properties of electrical conductivity and mechanical strength.) Because the PPE functionalizes the CNTs in a noncovalent manner, the functionalization does not damage the CNTs. The functionalization can also be exploited to improve the interactions between CNTs and epoxy matrices to enhance the properties of the resulting composite films. In addition to the CNTs, solvent, epoxy resin, epoxy hardener, and PPE, a properly formulated solution also includes a small amount of polycarbonate, which serves to fill voids that, if allowed to remain, would degrade the performance of the film. To form the film, the solution is drop-cast or spin-cast, then the solvent is allowed to evaporate.

Effect of electrical current on the tribological behavior of the Cu-WS2-G composites in air and vacuum

NASA Astrophysics Data System (ADS)

Qian, Gang; Feng, Yi; Li, Bin; Huang, Shiyin; Liu, Hongjuan; Ding, Kewang

2013-03-01

As the traditional graphite-based composites cannot meet the requirement of rapid developing modern industry, novel sliding electrical contact materials with high self-lubricating performance in multiple environments are eagerly required. Herein a copper-based composite with WS2 and graphite as solid lubricant are fabricated by powder metallurgy hot-pressed method. The friction and wear behaviors of the composites with and without current are investigated under the condition with sliding velocity of 10 m/s and normal load of 2.5 N/cm2 in both air and vacuum. Morphologies of the worn surfaces are observed by optical microscope and compositions of the lubricating films are analyzed by XPS. Surface profile curves and roughness of the worn surfaces are obtained by 2205 surface profiler. The results of wear tests show that the friction coefficient and wear volume loss of the composites with current are greater than that without current in both air and vacuum due to the adverse effects of electrical current which damaged the lubricating film partially and roughed the worn surfaces. XPS results demonstrate that the lubricating film formed in air is composed of oxides of Cu, WS2, elemental S and graphite, while the lubricating film formed in vacuum is composed of Cu, WS2 and graphite. Because of the synergetic lubricating action of oxides of Cu, WS2 and graphite, the composites show low friction coefficient and wear volume loss in air condition. Owing to the fact that graphite loses its lubricity which makes WS2 become the only lubricant, severe adhesive and abrasive wear occur and result in a high value of wear rate in vacuum condition. The formation of the lubricating film on the contact interface between the brush and ring is one of the factors which can greatly affect the wear performance of the brushes. The low contact voltage drop of the composites in vacuum condition is attributed to the high content of Cu in the surface film. This study fabricated a kind of new sliding electrical contact self-lubricating composite with dual-lubricant which can work well in both air and vacuum environments and provides a comprehensive analysis on the lubrication mechanisms of the composite.

Development of an embedded thin-film strain-gauge-based SHM network into 3D-woven composite structure for wind turbine blades

NASA Astrophysics Data System (ADS)

Zhao, Dongning; Rasool, Shafqat; Forde, Micheal; Weafer, Bryan; Archer, Edward; McIlhagger, Alistair; McLaughlin, James

2017-04-01

Recently, there has been increasing demand in developing low-cost, effective structure health monitoring system to be embedded into 3D-woven composite wind turbine blades to determine structural integrity and presence of defects. With measuring the strain and temperature inside composites at both in-situ blade resin curing and in-service stages, we are developing a novel scheme to embed a resistive-strain-based thin-metal-film sensory into the blade spar-cap that is made of composite laminates to determine structural integrity and presence of defects. Thus, with fiberglass, epoxy, and a thinmetal- film sensing element, a three-part, low-cost, smart composite laminate is developed. Embedded strain sensory inside composite laminate prototype survived after laminate curing process. The internal strain reading from embedded strain sensor under three-point-bending test standard is comparable. It proves that our proposed method will provide another SHM alternative to reduce sensing costs during the renewable green energy generation.

Aluminum-thin-film packaged fiber Bragg grating probes for monitoring the maximum tensile strain of composite materials.

PubMed

Im, Jooeun; Kim, Mihyun; Choi, Ki-Sun; Hwang, Tae-Kyung; Kwon, Il-Bum

2014-06-10

In this paper, new fiber Bragg grating (FBG) sensor probes are designed to intermittently detect the maximum tensile strain of composite materials, so as to evaluate the structural health status. This probe is fabricated by two thin Al films bonded to an FBG optical fiber and two supporting brackets, which are fixed on the surface of composite materials. The residual strain of the Al packaged FBG sensor probe is induced by the strain of composite materials. This residual strain can indicate the maximum strain of composite materials. Two types of sensor probes are prepared-one is an FBG with 18 μm thick Al films, and the other is an FBG with 36 μm thick Al films-to compare the thickness effect on the detection sensitivity. These sensor probes are bonded on the surfaces of carbon fiber reinforced plastics composite specimens. In order to determine the strain sensitivity between the residual strain of the FBG sensor probe and the maximum strain of the composite specimen, tensile tests are performed by universal testing machine, under the loading-unloading test condition. The strain sensitivities of the probes, which have the Al thicknesses of 18 and 36 μm, are determined as 0.13 and 0.23, respectively.

Synthesis and characterization of magnesium aluminate (MgAl2O4) spinel (MAS) thin films

NASA Astrophysics Data System (ADS)

Ahmad, Syed Muhammad; Hussain, Tousif; Ahmad, Riaz; Siddiqui, Jamil; Ali, Dilawar

2018-01-01

In a quest to identify more economic routes for synthesis of magnesium aluminate (MgAl2O4) spinel (MAS) thin films, dense plasma focus device was used with multiple plasma focus shots. Structural, bonding between composite films, surface morphological, compositional and hardness properties of MAS thin films were investigated by using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive x-rays (EDX) analysis and Vickers micro hardness test respectively. In XRD graph, the presence of MgAl2O4 diffraction peaks in crystallographic orientations (222), (400) and (622) pointed out the successful formation of polycrystalline thin films of MgAl2O4 with face centered cubic structure. The FTIR spectrums showed a major common transmittance band at 697.95 cm-1 which belongs to MgAl2O4. SEM micrographs illustrated a mesh type, granular and multi layers microstructures with significant melting effects. EDX spectrum confirmed the existence of magnesium, oxygen and aluminum in MAS films. A common increasing behavior in micro-hardness of composite MgAl2O4 films by increasing number of plasma focus shots was found.

Development and Characterization of Biodegradable Composite Films Based on Gelatin Derived from Beef, Pork and Fish Sources

PubMed Central

Nur Hanani, Zainal A.; Beatty, Eddie; Roos, Yrjo H.; Morris, Mick A.; Kerry, Joseph P.

2012-01-01

The objectives of this study were to develop composite films using various gelatin sources with corn oil (CO) incorporation (55.18%) and to investigate the mechanical and physical properties of these films as potential packaging films. There were increases (p < 0.05) in the tensile strength (TS) and puncture strength (PS) of films when the concentration of gelatin increased. The mechanical properties of these films were also improved when compared with films produced without CO. Conversely, the water barrier properties of composite films decreased (p < 0.05) when the concentration of gelatin in composite films increased. Comparing with pure gelatin films, water and oxygen barrier properties of gelatin films decreased when manufactured with the inclusion of CO. PMID:28239092

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shojaee, S. A.; Qi, Y.; Wang, Y. Q.

Ion irradiation is an alternative to heat treatment for transforming organic-inorganic thin films to a ceramic state. One major shortcoming in previous studies of ion-irradiated films is the assumption that constituent phases in ion-irradiated and heat-treated films are identical and that the ion irradiation effect is limited to changes in composition. Here, we investigate the effects of ion irradiation on both the composition and structure of constituent phases and use the results to explain the measured elastic modulus of the films. Our results indicated that the microstructure of the irradiated films consisted of carbon clusters within a silica matrix. Itmore » was found that carbon was present in a non-graphitic sp 2-bonded configuration. It was also observed that ion irradiation caused a decrease in the Si-O-Si bond angle of silica, similar to the effects of applied pressure. A phase transformation from tetrahedrally bonded to octahedrally bonded silica was also observed. The results indicated the incorporation of carbon within the silica network. Finally, a combination of the decrease in Si-O-Si bond angle and an increase in the carbon incorporation within the silica network was found to be responsible for the increase in the elastic modulus of the films.« less

Functional chitosan-based grapefruit seed extract composite films for applications in food packaging technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Y.M.; Lim, S.H.; Tay, B.Y.

Highlights: • Chitosan-based grapefruit seed extract (GFSE) films were solution casted. • GFSE was uniformly dispersed within all chitosan film matrices. • All chitosan-based composite films showed remarkable transparency. • Increasing amounts of GFSE incorporated increased the elongation at break of films. • Chitosan-based GFSE composite films inhibited the proliferation of fungal growth. - Abstract: Chitosan-based composite films with different amounts of grapefruit seed extract (GFSE) (0.5, 1.0 and 1.5% v/v) were fabricated via solution casting technique. Experimental results showed that GFSE was uniformly dispersed within all chitosan film matrices. The presence of GFSE made the films more amorphous andmore » tensile strength decreased, while elongation at break values increased as GFSE content increased. Results from the measurement of light transmission revealed that increasing amounts of GFSE (from 0.5 to 1.5% v/v) did not affect transparency of the films. Furthermore, packaging of bread samples with chitosan-based GFSE composite films inhibited the proliferation of fungal growth as compared to control samples. Hence, chitosan-based GFSE composite films have the potential to be a useful material in the area of food technology.« less

Magnetic quenching of photonic activity in Fe3O4-elastomer composite

NASA Astrophysics Data System (ADS)

Ma, Danhao; Hess, Dustin T.; Shetty, Pralav P.; Adu, Kofi W.; Bell, Richard C.; Terrones, Mauricio

2016-01-01

We report a quenching phenomenon within the visible region of the electromagnetic spectrum in the photonic response of a passive Fe3O4-silicone elastomer composite film due to magnetically aligned Fe3O4 nanoparticles. We performed systematic studies of the polarization dependence, the effect of particle size, and an in- and out-of-plane particle alignment on the optical response of the Fe3O4-silicone elastomer composites using a UV/vis/NIR spectrometer. We observed systematic redshifts in the response of the out-of-plane composite films with increasing particle alignment and weight that are attributed to dipole-induced effects. There were no observable shifts in the spectra of the in-plane films, suggesting the orientation of the magnetic dipole and the induced electric dipole play a crucial role in the optical response. A dramatic suppression to near quenching of the photonic response occurred in films containing moderate concentrations of the aligned nanoparticles. This is attributed to the interplay between the intra- and the interparticle dipoles. This occurred even when low magnetic fields were used during the curing process, suggesting that particle alignment and particle size limitation are critical in the manipulation of the photonic properties. A dipole approximation model is used to explain the quenching phenomenon. An active system of such a composite has a potential application in magneto-optic switches.

The zinc-loss effect and mobility enhancement of DUV-patterned sol-gel IGZO thin-film transistors

NASA Astrophysics Data System (ADS)

Wang, Kuan-Hsun; Zan, Hsiao-Wen; Soppera, Olivier

2018-03-01

We investigate the composition of the DUV-patterned sol-gel indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) and observe a significant zinc loss effect during developing when the DUV exposure is insufficient. The zinc loss, however, is beneficial for increasing the mobility. Reducing zinc to indium composition ratio from 0.5 to 0.02 can effectively increase mobility from 0.27 to 7.30 cm2 V-1 s-1 when the gallium to indium ratio is fixed as 0.25 and the post annealing process is fixed as 300 °C for 2 h. On the other hand, an IGO TFT fails to deliver a uniform film and a reproducible TFT performance, revealing the critical role of zinc in forming homogeneous IGZO TFTs.

Studies of Lubricating Materials in Vacuum

NASA Technical Reports Server (NTRS)

Buckley, D. H.; Johnson, R. L.; Swikert, M. A.

1964-01-01

Lubricating materials for use in a vacuum environment have been the subject of a series of experimental investigations. Evaporation properties were evaluated for solid polymeric compositions. Friction and wear studies explored the behavior during sliding contact for series of polymeric compositions, binary alloys containing soft film-forming phases, complex alloys with film-forming materials, and a burnished MoS2 film. Friction and wear experiments were conducted at 10(exp-9)mm Hg with a 3/16-inch-radius-hemisphere rider specimen sliding on the flat surface of a rotating 2-1/2-inch-diameter disk specimen with materials that had low rates of evaporation. The influence of fillers in polytetrafluoroethylene (PTFE) on decomposition during vacuum friction studies was determined with a mass spectrometer. A real advantage in reducing decomposition and improving friction wear properties is gained by adding fillers (e.g., copper) that improve thermal conductivity through the composite materials. A polyimide and an epoxy-MoS2 composition material were found to have better friction and wear properties than PTFE compositions. A series of alloys (cast binary as well as more complex alloys) that contained microinclusions of potential film-forming material was studied. These materials replaced the normal surface oxides as they were worn away on sliding contact. Iron sulfide, nickel oxide, and tin are typical film-forming materials employed and were demonstrated to be effective in inhibiting surface welding and reducing friction. A burnished MoS2 film applied to type 440-C stainless steel in argon with a rotating soft wire brush had good endurance properties but somewhat higher friction than commercially available bonded films. An oil film applied to the burnished MoS2 markedly reduced its endurance life.

Charged Nanowire-Directed Growth of Amorphous Calcium Carbonate Nanosheets in a Mixed Solvent for Biomimetic Composite Films.

PubMed

Liu, Yang-Yi; Liu, Lei; Chen, Si-Ming; Chang, Fu-Jia; Mao, Li-Bo; Gao, Huai-Ling; Ma, Tao; Yu, Shu-Hong

2018-05-22

Bio-inspired mineralization is an effective way for fabricating complex inorganic materials, which inspires us to develop new methods to synthesize materials with fascinating properties. In this article, we report that the charged tellurium nanowires (TeNWs) can be used as biomacromolecule analogues to direct the formation of amorphous calcium carbonate (ACC) nanosheets (ACCNs) in a mixed solvent. The effects of surface charges and the concentration of the TeNWs on the formation of ACCNs have been investigated. Particularly, the produced ACCNs can be functionalized by Fe 3 O 4 nanoparticles to produce magnetic ACC/Fe 3 O 4 hybrid nanosheets that can be used to construct ACC/Fe 3 O 4 composite films through a self-evaporation process. Moreover, sodium alginate-ACC nanocomposite films with remarkable toughness and good transmittance can also be fabricated by using such ACCNs as nanoscale building blocks. This mineralization approach in a mixed solvent using charged TeNWs as biomacromolecule analogues provides a new way for the synthesis of ACCNs, which can be used as nanoscale building blocks for the fabrication of biomimetic composite films.

Investigation of the influence of the composition on mechanical properties of polylactide

NASA Astrophysics Data System (ADS)

Baikin, A. S.; Sevostyanov, M. A.; Nasakina, E. O.; Sergienko, K. V.; Kaplan, M. A.; Konushkin, S. V.; Kolmakova, A. A.; Yakubov, A. D.; Kolmakov, A. G.

2018-04-01

In this paper we describe the creation of films from polylactide. Studied the mechanical properties of developed polymer films of polylactide. The effect of the molecular weight of polylactide on the mechanical properties of the resulting polymer films is shown. The dependence of the mechanical properties of polylactide films on the polymer concentration in chloroform was studied. The possibility of creating biodegradable films with specified mechanical properties is shown.

Preparation of Polyurethane/Graphite Composite Films with Stable Mechanical Property and Wear Resistance Underwater.

PubMed

Wang, Miaomiao; Wang, Zubin; Chen, Qirong; Meng, Xiangfu; Heng, Liping

2018-06-01

The wear resistance and stable mechanical properties affect the service life of the underwater functional materials to a certain extent. Unfortunately, the current study of underwater functional materials is rarely related to these aspects. Herein, we successfully designed and prepared polyurethane/graphite nanosheet (PU/GN) composite materials, which exhibited excellent wear resistance and stable mechanical properties underwater. The PU/GN composite films were prepared by evaporating a mixed solution of PU and GN on concave hexagonal honeycomb silicon templates. The mechanical properties of the composite films were determined by tensile test, and the wear resistance was evaluated by comparing the surface morphology before and after grind. By adjusting the content of graphite in the composite films, we found that the composite films containing 23 wt% GN had higher tensile strength and superior wear resistance. Moreover, this composite film showed an outstanding stability when expose to water. The impressive results along with simple preparation process made PU/GN composite films had potential applications in robust underwater functional materials.

Ion irradiation induced structural modifications and increase in elastic modulus of silica based thin films

PubMed Central

Shojaee, S. A.; Qi, Y.; Wang, Y. Q.; Mehner, A.; Lucca, D. A.

2017-01-01

Ion irradiation is an alternative to heat treatment for transforming organic-inorganic thin films to a ceramic state. One major shortcoming in previous studies of ion-irradiated films is the assumption that constituent phases in ion-irradiated and heat-treated films are identical and that the ion irradiation effect is limited to changes in composition. In this study, we investigate the effects of ion irradiation on both the composition and structure of constituent phases and use the results to explain the measured elastic modulus of the films. The results indicated that the microstructure of the irradiated films consisted of carbon clusters within a silica matrix. It was found that carbon was present in a non-graphitic sp2-bonded configuration. It was also observed that ion irradiation caused a decrease in the Si-O-Si bond angle of silica, similar to the effects of applied pressure. A phase transformation from tetrahedrally bonded to octahedrally bonded silica was also observed. The results indicated the incorporation of carbon within the silica network. A combination of the decrease in Si-O-Si bond angle and an increase in the carbon incorporation within the silica network was found to be responsible for the increase in the elastic modulus of the films. PMID:28071696

Ion irradiation induced structural modifications and increase in elastic modulus of silica based thin films

DOE PAGES

Shojaee, S. A.; Qi, Y.; Wang, Y. Q.; ...

2017-01-10

Ion irradiation is an alternative to heat treatment for transforming organic-inorganic thin films to a ceramic state. One major shortcoming in previous studies of ion-irradiated films is the assumption that constituent phases in ion-irradiated and heat-treated films are identical and that the ion irradiation effect is limited to changes in composition. Here, we investigate the effects of ion irradiation on both the composition and structure of constituent phases and use the results to explain the measured elastic modulus of the films. Our results indicated that the microstructure of the irradiated films consisted of carbon clusters within a silica matrix. Itmore » was found that carbon was present in a non-graphitic sp 2-bonded configuration. It was also observed that ion irradiation caused a decrease in the Si-O-Si bond angle of silica, similar to the effects of applied pressure. A phase transformation from tetrahedrally bonded to octahedrally bonded silica was also observed. The results indicated the incorporation of carbon within the silica network. Finally, a combination of the decrease in Si-O-Si bond angle and an increase in the carbon incorporation within the silica network was found to be responsible for the increase in the elastic modulus of the films.« less

Preparation of buccal patch composed of carbopol, poloxamer and hydroxypropyl methylcellulose.

PubMed

Chun, Myung-Kwan; Kwak, Byoung-Tae; Choi, Hoo-Kyun

2003-11-01

A polymeric film composed of Carbopol, Poloxamer and hydroxypropyl methylcellulose was prepared to develop a buccal patch and the effects of composition of the film on adhesion time, swelling ratio, and dissolution of the film were studied. The effects of plasticizers or penetration enhancers on the release of triamcinolone acetonide (TAA) were also studied. The hydrogen bonding between Carbopol and Poloxamer played important role in reducing swelling ratio and dissolution rate of polymer film and increasing adhesion time. The swelling ratio of the composite film was significantly reduced and the adhesion time was increased when compared with Carbopol film. As the ratio of Poloxamer to hydroxypropyl methylcellulose increased from 0/66 to 33/33, the release rate of TAA decreased. However, no further significant decrease of release rate was observed beyond the ratio of 33/33. The release rate of TAA in the polymeric film containing polyethylene glycol 400, a plasticizer, showed the highest release rate followed by triethyl citrate, and castor oil. The release rate of TAA from the polymeric film containing permeation enhancers was slower than that from the control without enhancers. Therefore, these observations indicated that a preparation of a buccal patch is feasible with the polymeric film composed of Cabopol, Poloxamer and hydropropyl methylcellulose.

Graphene/Ionic Liquid Composite Films and Ion Exchange

PubMed Central

Mo, Yufei; Wan, Yunfang; Chau, Alicia; Huang, Fuchuan

2014-01-01

Wettability of graphene is adjusted by the formation of various ionic surfaces combining ionic liquid (IL) self-assembly with ion exchange. The functionalized ILs were designed and synthesized with the goal of obtaining adjustable wettability. The wettability of the graphene surface bearing various anions was measured systematically. The effect of solvent systems on ion exchange ratios on the graphene surface has also been investigated. Meanwhile, the mechanical properties of the graphene/IL composite films were investigated on a nanometer scale. The elasticity and adhesion behavior of the thin film was determined with respected to the indentation deformation by colloid probe nanoindentation method. The results indicate that anions played an important role in determining graphene/IL composite film properties. In addition, surface wetting and mechanics can be quantitatively determined according to the counter-anions on the surface. This study might suggest an alternate way for quantity detection of surface ions by surface force. PMID:24970602

Control of the Structure of Diffusion Layer in Carbon Steels Under Nitriding with Preliminary Deposition of Copper Oxide Catalytic Films

NASA Astrophysics Data System (ADS)

Petrova, L. G.; Aleksandrov, V. A.; Malakhov, A. Yu.

2017-07-01

The effect of thin films of copper oxide deposited before nitriding on the phase composition and the kinetics of growth of diffusion layers in carbon steels is considered. The process of formation of an oxide film involves chemical reduction of pure copper on the surface of steel specimens from a salt solution and subsequent oxidation under air heating. The oxide film exerts a catalytic action in nitriding of low- and medium-carbon steels, which consists in accelerated growth of the diffusion layer, the nitride zone in the first turn. The kinetics of the nitriding process and the phase composition of the layer are controlled by the thickness of the copper oxide precursor, i.e., the deposited copper film.

Preparation, Characterization and Thermo-Chromic Properties of EVA/VO2 Laminate Films for Smart Window Applications and Energy Efficiency in Building

PubMed Central

Srirodpai, Onruthai; Wootthikanokkhan, Jatuphorn; Nawalertpanya, Saiwan; Yuwawech, Kitti; Meeyoo, Vissanu

2017-01-01

Thermochromic films based on vanadium dioxide (VO2)/ethylene vinyl acetate copolymer (EVA) composite were developed. The monoclinic VO2 particles was firstly prepared via hydrothermal and calcination processes. The effects of hydrothermal time and tungsten doping agent on crystal structure and morphology of the calcined metal oxides were reported. After that, 1 wt % of the prepared VO2 powder was mixed with EVA compound, using two different mixing processes. It was found that mechanical properties of the EVA/VO2 films prepared by the melt process were superior to those of which prepared by the solution process. On the other hand, percentage visible light transmittance of the solution casted EVA/VO2 film was greater than that of the melt processed composite film. This was related to the different gel content of EVA rubber and state of dispersion and distribution of VO2 within the polymer matrix phase. Thermochromic behaviors and heat reflectance of the EVA/VO2 film were also verified. In overall, this study demonstrated that it was possible to develop a thermochromic film using the polymer composite approach. In this regard, the mixing condition was found to be one of the most important factors affecting morphology and thermo-mechanical properties of the films. PMID:28772413

Influence of the simultaneous addition of bentonite and cellulose fibers on the mechanical and barrier properties of starch composite-films.

PubMed

de Moraes, J Oliveira; Müller, C M O; Laurindo, J B

2012-02-01

The addition of nanoclay or cellulose fibers has been presented in the literature as a suitable alternative for reinforcing starch films. The aim of the present work was to evaluate the effect of the simultaneous incorporation of nanoclay (bentonite) and cellulose fibers on the mechanical and water barrier properties of the resultant composite-films. Films were prepared by casting with 3% in weight of cassava starch, using glycerol as plasticizer (0.30 g per g of starch), cellulose fibers at a concentration of 0.30 g of fibers per g of starch and nanoclay (0.05 g clay per g starch and 0.10 g clay per g starch). The addition of cellulose fibers and nanoclay increased the tensile strength of the films 8.5 times and the Young modulus 24 times but reduced the elongation capacity 14 times. The water barrier properties of the composite-films to which bentonite and cellulose fibers were added were approximately 60% inferior to those of starch films. Diffractograms showed that the nanoclay was intercalated in the polymeric matrix. These results indicate that the simultaneous addition of bentonite and cellulose fibers is a suitable alternative to increase the tensile strength of the films and decrease their water vapor permeabilities.

Compositional Dependence of Optical and Structural Properties of Nanogranular Mixed ZrO2/ZnO/SnO2 Thin Film

NASA Astrophysics Data System (ADS)

Salari, S.; Ghodsi, F. E.

2018-06-01

A study on the optical properties and photoluminescence (PL) spectra of ternary oxide nanogranular thin films comprising Zr, Zn, and Sn revealed that the change in component ratio could direct the roadmap to improve characteristics of the films. Grazing angle X-ray diffraction analysis showed that incorporation of Sn atoms into the tetragonal structure of Zn/Zr thin film resulted in an amorphous structure. The band gap of film was tunable by precisely controlling the concentration of components. The widening of band gap could correlate to the quantum confinement effect. PL spectra of the composite thin films under excitation at 365 nm showed a sharp red emission with relatively Gaussian line shape, which was intensified in the optimum percentage ratio of 50/30/20. This nearly red emission is attributed to the radiative emission of electrons captured at low-energy traps located near the valence band. An optimum red emission is strongly desirable for use in white LEDs. The comparative study on FTIR spectra of unary, binary, and ternary thin films confirmed successful composition of three different metal oxides in ternary thin films. Detailed investigation on FTIR spectra of ternary compounds revealed that the quenching in PL emission at higher percentage of Sn was originally due to the hydroxyl group.

Preparation, Characterization and Thermo-Chromic Properties of EVA/VO₂ Laminate Films for Smart Window Applications and Energy Efficiency in Building.

PubMed

Srirodpai, Onruthai; Wootthikanokkhan, Jatuphorn; Nawalertpanya, Saiwan; Yuwawech, Kitti; Meeyoo, Vissanu

2017-01-11

Thermochromic films based on vanadium dioxide (VO₂)/ethylene vinyl acetate copolymer (EVA) composite were developed. The monoclinic VO₂ particles was firstly prepared via hydrothermal and calcination processes. The effects of hydrothermal time and tungsten doping agent on crystal structure and morphology of the calcined metal oxides were reported. After that, 1 wt % of the prepared VO₂ powder was mixed with EVA compound, using two different mixing processes. It was found that mechanical properties of the EVA/VO₂ films prepared by the melt process were superior to those of which prepared by the solution process. On the other hand, percentage visible light transmittance of the solution casted EVA/VO₂ film was greater than that of the melt processed composite film. This was related to the different gel content of EVA rubber and state of dispersion and distribution of VO₂ within the polymer matrix phase. Thermochromic behaviors and heat reflectance of the EVA/VO₂ film were also verified. In overall, this study demonstrated that it was possible to develop a thermochromic film using the polymer composite approach. In this regard, the mixing condition was found to be one of the most important factors affecting morphology and thermo-mechanical properties of the films.

Role of Thickness Confinement on Relaxations of the Fast Component in a Miscible A/B Blend

DOE Office of Scientific and Technical Information (OSTI.GOV)

Green, Peter; Sharma, Ravi P.; Dong, Ban Xuan

Spatial compositional heterogeneity strongly influences the dynamics of the A and B components of bulk miscible blends. Its effects are especially apparent in mixtures, such as poly(vinyl methyl ether) (PVME)/polystyrene (PS), where there exist significant disparities between the component glass transition temperatures (Tgs) and relaxation times. The relaxation processes characterized by distinct temperature dependencies and relaxation rates manifest different local compositional environments for temperatures above and below the glass transition temperature of the miscible blend. This same behavior is shown to exist in miscible PS/PVME films as thin as 100 nm. Moreover, in thin films, the characteristic segmental relaxation timesmore » t of the PVME component of miscible PVME/PS blends confined between aluminum (Al) substrates decrease with increasing molecular weight M of the PS component. These relaxation rates are film thickness dependent, in films up to a few hundred nanometers in thickness. This is in remarkable contrast to homopolymer films, where thickness confinement effects are apparent only on length scales on the order of nanometers. These surprisingly large length scales and M dependence are associated with the preferential interfacial enrichment - wetting layer formation - of the PVME component at the external Al interfaces, which alters the local spatial blend composition within the interior of the film. The implications are that the dynamics of miscible thin film blends are dictated in part by component Tg differences, disparities in component relaxation rates, component-substrate interactions, and chain lengths (entropy of mixing).« less

Preparation and application of agar/alginate/collagen ternary blend functional food packaging films.

PubMed

Wang, Long-Feng; Rhim, Jong-Whan

2015-09-01

Ternary blend agar/alginate/collagen (A/A/C) hydrogel films with silver nanoparticles (AgNPs) and grapefruit seed extract (GSE) were prepared. Their performance properties, transparency, tensile strength (TS), water vapor permeability (WVP), water contact angle (CA), water swelling ratio (SR), water solubility (WS), and antimicrobial activity were determined. The A/A/C film was highly transparent, and both AgNPs and GSE incorporated blend films (A/A/C(AgNPs) and A/A/C(GSE)) exhibited UV-screening effect, especially, the A/A/C(GSE) film had high UV-screening effect without sacrificing the transmittance. In addition, the A/A/C blend films formed efficient hydrogel film with the water holding capacity of 23.6 times of their weight. Both A/A/C(AgNPs) and A/A/C(GSE) composite films exhibited strong antimicrobial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli) food-borne pathogenic bacteria. The test results of fresh potatoes packaging revealed that all the A/A/C ternary blend films prevented forming of condensed water on the packaged film surface, both A/A/C(AgNPs) and A/A/C(GSE) composite films prevented greening of potatoes during storage. The results indicate that the ternary blend hydrogel films incorporated with AgNPs or GSE can be used not only as antifogging packaging films for highly respiring fresh agriculture produce, but also as an active food packaging system utilizing their strong antimicrobial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

Direct Electrospray Printing of Gradient Refractive Index Chalcogenide Glass Films.

PubMed

Novak, Spencer; Lin, Pao Tai; Li, Cheng; Lumdee, Chatdanai; Hu, Juejun; Agarwal, Anuradha; Kik, Pieter G; Deng, Weiwei; Richardson, Kathleen

2017-08-16

A spatially varying effective refractive index gradient using chalcogenide glass layers is printed on a silicon wafer using an optimized electrospray (ES) deposition process. Using solution-derived glass precursors, IR-transparent Ge 23 Sb 7 S 70 and As 40 S 60 glass films of programmed thickness are fabricated to yield a bilayer structure, resulting in an effective gradient refractive index (GRIN) film. Optical and compositional analysis tools confirm the optical and physical nature of the gradient in the resulting high-optical-quality films, demonstrating the power of direct printing of multimaterial structures compatible with planar photonic fabrication protocols. The potential application of such tailorable materials and structures as they relate to the enhancement of sensitivity in chalcogenide glass based planar chemical sensor device design is presented. This method, applicable to a broad cross section of glass compositions, shows promise in directly depositing GRIN films with tunable refractive index profiles for bulk and planar optical components and devices.

Electrophoretic-deposited CNT/MnO2 composites for high-power electrochemical energy storage/conversion applications

NASA Astrophysics Data System (ADS)

Xiao, Wei; Xia, Hui; Fuh, Jerry Y. H.; Lu, Li

2010-05-01

CNT/MnO2 (birnessite-type) composite films have been successfully deposited on Ni-foil substrate via electrophoretic deposition (EPD). The unique EPD CNT/MnO2 composite film electrode shows enhanced electrical conductivity, good contact between composite films and the substrate and open porous structure, which makes the EPD composite films a promising electrode for high-power supercapacitors and lithium ion batteries.

Multiple Interfacial Fe3O4@BaTiO3/P(VDF-HFP) Core-Shell-Matrix Films with Internal Barrier Layer Capacitor (IBLC) Effects and High Energy Storage Density.

PubMed

Zhou, Ling; Fu, Qiuyun; Xue, Fei; Tang, Xiahui; Zhou, Dongxiang; Tian, Yahui; Wang, Geng; Wang, Chaohong; Gou, Haibo; Xu, Lei

2017-11-22

Flexible nanocomposites composed of high dielectric constant fillers and polymer matrix have shown great potential for electrostatic capacitors and energy storage applications. To obtain the composited material with high dielectric constant and high breakdown strength, multi-interfacial composited particles, which composed of conductive cores and insulating shells and possessed the internal barrier layer capacitor (IBLC) effect, were adopted as fillers. Thus, Fe 3 O 4 @BaTiO 3 core-shell particles were prepared and loaded into the poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) polymer matrix. As the mass fraction of core-shell fillers increased from 2.5 wt % to 30 wt %, the dielectric constant of the films increased, while the loss tangent remained at a low level (<0.05 at 1 kHz). Both high electric displacement and high electric breakdown strength were achieved in the films with 10 wt % core-shell fillers loaded. The maximum energy storage density of 7.018 J/cm 3 was measured at 2350 kV/cm, which shows significant enhancement than those of the pure P(VDF-HFP) films and analogous composited films with converse insulating-conductive core-shell fillers. A Maxwell-Wagner capacitor model was also adopted to interpret the efficiency of IBLC effects on the suppressed loss tangent and the superior breakdown strength. This work explored an effective approach to prepare dielectric nanocomposites for energy storage applications experimentally and theoretically.

Novel behaviors of anomalous Hall effect in TbFeCo ferrimagnetic thin films

NASA Astrophysics Data System (ADS)

Ando, Ryo; Komine, Takashi; Sato, Shiori; Kaneta, Shingo; Hara, Yoshiaki

2018-05-01

We investigate the temperature dependence and the thickness dependence of anomalous Hall effect (AHE) of TbFeCo ultra-thin films under high magnetic field. The sign change on temperature dependence of AHE in 20nm-thick TbFeCo film with rare-earth (RE) rich composition was observed. The AHE sign at low temperature is negative while it gradually becomes positive as the temperature increases. Moreover, the AHE sign for 5nm-thick TbFeCo film remains positive while that for 50nm-thick TbFeCo film remains negative at temperature in the range from 5 K to 400 K. The similar thickness dependence of AHE in TM-rich samples was also observed. From the mean-field approximation, the sign change temperature in AHE is related to the compensation temperature and the existence of interfacial region, which has the TM-rich composition and the weak anisotropy. Therefore, We clarified that the novel behavior of AHE sign changes in TbFeCo thin films with different thickness can be explained by the interfacial layer with weak anisotropy and two phase model.

Preparation of poly (arylene ether nitrile)/NzdFeB composite film with excellent thermal properties and tensile strength

NASA Astrophysics Data System (ADS)

Pan, Hai; Xu, Mingzhen; Liu, Xiaobo

2017-12-01

PEN/NdFeB composite films were prepared by the solution casting method. The thermal properties, fracture morphology and tensile strength of the composite films were tested by DSC, TGA, SEM and electromechanical universal testing machine, respectively. The results reveal that the composite film has good thermal properties and tensile strength. Glass-transition temperature and decomposition temperatures at weight loss of 5% ot the composite films retain at 166±1 C and 462±4 C, respectively. The composite film with 5 wt.% NdFeB has the best tensile strength value for 100.5 MPa. In addition, it was found that the NdFeB filler was well dispersed in PEN matrix by SEM analysis.

Amorphous Metal Oxide Thin Films from Aqueous Precursors: New Routes to High-kappa Dielectrics, Impact of Annealing Atmosphere Humidity, and Elucidation of Non-Uniform Composition Profiles

NASA Astrophysics Data System (ADS)

Woods, Keenan N.

Metal oxide thin films serve as critical components in many modern technologies, including microelectronic devices. Industrial state-of-the-art production utilizes vapor-phase techniques to make high-quality (dense, smooth, uniform) thin film materials. However, vapor-phase techniques require large energy inputs and expensive equipment and precursors. Solution-phase routes to metal oxides have attracted great interest as cost-effective alternatives to vapor-phase methods and also offer the potential of large-area coverage, facile control of metal composition, and low-temperature processing. Solution deposition has previously been dominated by sol-gel routes, which utilize organic ligands, additives, and/or solvents. However, sol-gel films are often porous and contain residual carbon impurities, which can negatively impact device properties. All-inorganic aqueous routes produce dense, ultrasmooth films without carbon impurities, but the mechanisms involved in converting aqueous precursors to metal oxides are virtually unexplored. Understanding these mechanisms and the parameters that influence them is critical for widespread use of aqueous approaches to prepare microelectronic components. Additionally, understanding (and controlling) density and composition inhomogeneities is important for optimizing electronic properties. An overview of deposition approaches and the challenges facing aqueous routes are presented in Chapter I. A summary of thin film characterization techniques central to this work is given in Chapter II. This dissertation contributes to the field of solution-phase deposition by focusing on three areas. First, an all-inorganic aqueous route to high-kappa metal oxide dielectrics is developed for two ternary systems. Chapters III and IV detail the film formation chemistry and film properties of lanthanum zirconium oxide (LZO) and zirconium aluminum oxide (ZAO), respectively. The functionality of these dielectrics as device components is also demonstrated. Second, the impact of steam annealing on the evolution of aqueous-derived films is reported. Chapter V demonstrates that steam annealing lowers processing temperatures by effectively reducing residual counterion content, improving film stability with respect to water absorption, and enhancing dielectric properties of LZO films. Third, density and composition inhomogeneities in aqueous-derived films are investigated. Chapters VI and VII examine density inhomogeneities in single- and multi-metal component thin films, respectively, and show that these density inhomogeneities are related to inhomogeneous metal component distributions. This dissertation includes previously published coauthored material.

Thermochromic effect in synthetic opal/polyaniline composite structures

NASA Astrophysics Data System (ADS)

Rahman, F.; Khokhar, A. Z.

2009-02-01

The design and construction of a novel storage/indicator bilayer system is described where ammonia gas stored in a porous material can be used to dope a colour-changing polyaniline film. Both reversible and irreversible colour change effects are possible. A thin synthetic opal film is coupled to a polyaniline film in a parallel plate glass cell with ammonia gas adsorbed on the silica balls that form the opal structure. When heated and cooled, ammonia reversibly exchanges between the opal and polyaniline films causing a very distinct change in the colour of the polyaniline film. This thermochromic effect is also electrically detectable because of the large concomitant change in the resistivity of the polyaniline film that accompanies its colour change.

Deposition of BN interphase coatings from B-trichloroborazine and its effects on the mechanical properties of SiC/SiC composites

NASA Astrophysics Data System (ADS)

Wu, Haitang; Chen, Mingwei; Wei, Xi; Ge, Min; Zhang, Weigang

2010-12-01

Boron nitride thin films were deposited on silicon carbide fibers by chemical vapor deposition at atmospheric pressure from the single source precursor B-trichloroborazine (Cl 3B 3N 3H 3, TCB). The film growth and structure, as a function of deposition temperature, hydrogen gas flow rate, and deposition time, were discussed. The deposition rate reaches a maximum at 1000 °C, then decreases with the increasing of temperature, and the apparent activation energy of the reaction is 127 kJ/mol. Above 1000 °C, gas-phase nucleation determines the deposition process. The deposited BN films were characterized by Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of BN interphase on the mechanical properties of the unidirectional SiC fiber-reinforced SiC matrix (SiC/SiC) composites was also investigated. The results show that the flexural strength of SiC/SiC composites with and without coating is 276 MPa and 70 MPa, respectively, which indicates that BN interphase coating deposited from B-trichloroborazine precursor can effectively adjust the fiber/matrix interface, thus causing a dramatic increase in the mechanical properties of the composites.

Preparation of a porcine plasma protein composite film and its application.

PubMed

Lee, Ji-Hyun; Song, Kyung Bin

2015-01-01

To use blood released from slaughtering houses, a porcine plasma protein (PPP)/nanoclay composite film was prepared. The tensile strength and elongation at break values of the PPP composite film with 5% nanoclay were 10.01 MPa and 6.55%, respectively. The PPP composite film containing 1% grapefruit seed extract (GSE) was applied to pork meat, and the populations of inoculated Escherichia coli O157:H7 and Listeria monocytogenes in the pork meat packaged with the PPP composite film decreased by 0.8 and 1.0 log CFU/g, respectively, after 7 days of storage compared to the populations of the control. In addition, thiobarbituric acid values in the pork meat packaged with the PPP composite film were less than those of the control sample during storage. These results suggest that the PPP nanocomposite film containing 1% GSE can be used as a packaging material to maintain the quality of pork meat.

Aligned Carbon Nanotubes for High-Performance Films and Composites

NASA Astrophysics Data System (ADS)

Zhang, Liwen

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Biomimetic synthesis of calcite films by a polymer-induced liquid-precursor (PILP) process. 1. Influence and incorporation of magnesium

NASA Astrophysics Data System (ADS)

Cheng, Xingguo; Varona, Philip L.; Olszta, Matthew J.; Gower, Laurie B.

2007-09-01

Magnesium-bearing calcium carbonate films have been synthesized via a polymer-induced liquid-precursor (PILP) mineralization process. A variety of morphological features of biominerals can be mimicked with this PILP process; therefore, our group has proposed that this crystallization system can be used as an effective in vitro model system for examining mechanistic issues related to biomineralization. Here, the effect of the Mg 2+/Ca 2+ ratio on the rate of transformation of the amorphous precursor films was investigated using polarized optical microscopy (POM), and the final crystalline structure and composition were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), inductively coupled plasma spectroscopy (ICP) and energy dispersive spectroscopy (EDS). The entrapment of high levels of magnesium in the deposited precursor films had a pronounced inhibitory effect on the amorphous to crystalline transformation, and furthermore, influenced the polycrystalline nature of the film. The magnesium content incorporated within the calcite lattice (8-26%) resembles the range found in biologically formed high magnesium-bearing calcite, while much lower levels were formed via the conventional solution crystallization process. The formation of non-equilibrium morphologies and similar compositions of magnesium-bearing calcite via the PILP process further supports our hypothesis that the PILP process may play a fundamental role in the formation of calcitic biominerals in nature. In the realm of biomimetic engineering, the PILP process may also establish itself as a new method to produce thin ceramic films with variable compositions under ambient conditions.

Growth of Cu2ZnSnSe4 Film under Controllable Se Vapor Composition and Impact of Low Cu Content on Solar Cell Efficiency.

PubMed

Li, Jianjun; Wang, Hongxia; Wu, Li; Chen, Cheng; Zhou, Zhiqiang; Liu, Fangfang; Sun, Yun; Han, Junbo; Zhang, Yi

2016-04-27

It is a challenge to fabricate high quality Cu2ZnSnSe4 (CZTSe) film with low Cu content (Cu/(Zn + Sn) < 0.8). In this work, the growth mechanisms of CZTSe films under different Se vapor composition are investigated by DC-sputtering and a postselenization approach. The composition of Se vapor has important influence on the compactability of the films and the diffusion of elements in the CZTSe films. By adjusting the composition of Se vapor during the selenization process, an optimized two step selenization process is proposed and highly crystallized CZTSe film with low Cu content (Cu/(Zn + Sn) = 0.75) is obtained. Further study of the effect of Cu content on the morphology and photovoltaic performance of the corresponding CZTSe solar cells has shown that the roughness of the CZTSe absorber film increases when Cu content decreases. As a consequence, the reflection loss of CZTSe solar cells reduces dramatically and the short circuit current density of the cells improve from 34.7 mA/cm(2) for Cu/(Zn + Sn) = 0.88 to 38.5 mA/cm(2) for Cu/(Zn + Sn) = 0.75. In addition, the CZTSe solar cells with low Cu content show longer minority carrier lifetime and higher open circuit voltage than the high Cu content devices. A champion performance CZTSe solar cell with 10.4% efficiency is fabricated with Cu/(Zn + Sn) = 0.75 in the CZTSe film without antireflection coating.

Combining single source chemical vapour deposition precursors to explore the phase space of titanium oxynitride thin films.

PubMed

Rees, Kelly; Lorusso, Emanuela; Cosham, Samuel D; Kulak, Alexander N; Hyett, Geoffrey

2018-02-14

In this paper we report on a novel chemical vapour deposition approach to the formation and control of composition of mixed anion materials, as applied to titanium oxynitride thin films. The method used is the aerosol assisted chemical vapour deposition (AACVD) of a mixture of single source precursors. To explore the titanium-oxygen-nitrogen system the single source precursors selected were tetrakis(dimethylamido) titanium and titanium tetraisopropoxide which individually are precursors to thin films of titanium nitride and titanium dioxide respectively. However, by combining these precursors in specific ratios in a series of AACVD reactions at 400 °C, we are able to deposit thin films of titanium oxynitride with three different structure types and a wide range of compositions. Using this precursor system we can observe films of nitrogen doped anatase, with 25% anion doping of nitrogen; a new composition of pseudobrookite titanium oxynitride with a composition of Ti 3 O 3.5 N 1.5 , identified as being a UV photocatalyst; and rock-salt titanium oxynitride in the range TiO 0.41 N 0.59 to TiO 0.05 N 0.95 . The films were characterised using GIXRD, WDX and UV-vis spectroscopy, and in the case of the pseudobrookite films, assessed for photocatalytic activity. This work shows that a so-called dual single-source CVD approach is an effective method for the deposition of ternary mixed anion ceramic films through simple control of the ratio of the precursors, while keeping all other experimental parameters constant.

Montmorillonite/graphene oxide/chitosan composite: Synthesis, characterization and properties.

PubMed

Yadav, Mithilesh; Ahmad, Sharif

2015-08-01

The present work reports the successful preparation, thermal and mechanical characterization of high performance films of Na(+) montmorillonite (MMT)/graphene oxide (GO)/chitosan (CS) composite using simple solution mixing evaporation method. The formations of films were verified by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. The thermal stability and mechanical properties of these films were investigated by thermogravimetric analysis (TGA) and mechanical testing (Instron 8871). The results obtained from these studies revealed that the composites of chitosan, MMT, and graphene oxide were homogeneous in nature. A synergistic effect of MMT and GO reinforcing on chitosan matrix was observed for the first time, in case of 5 wt.% MMT and 1 wt.% GO. The tensile strength of (5 wt.%) MMT/(1 wt.%) GO/CS composite was formed 9±0.23% and 27±0.25% higher than that of the (1 wt.%) GO/CS composite and chitosan, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Thermoelectric properties of conducting polyaniline/BaTiO3 nanoparticle composite films

NASA Astrophysics Data System (ADS)

Anno, H.; Yamaguchi, K.; Nakabayashi, T.; Kurokawa, H.; Akagi, F.; Hojo, M.; Toshima, N.

2011-05-01

Conducting polyaniline (PANI)/BaTiO3 nanoparticle composite films with different molar ratio values R=1, 5, 10, and 100 have been prepared on a quartz substrate by casting the m-cresol solution of PANI, (±)-10-camphorsulfonic acid (CSA) and BaTiO3 nanoparticle with an average diameter of about 20 nm. The CSA-doped PANI/BaTiO3 composite films were characterized by x-ray diffraction, Fourier transform infrared spectroscopy, and UV-Vis transmission spectroscopy. The Seebeck coefficient and the electrical conductivity of the films with different R values, together with CSA-doped PANI films, were measured in the temperature range from room temperature to ~400 K. The relation between the Seebeck coefficient and the electrical conductivity in the composite films are discussed from a comparison of them with those of CSA-doped PANI films and other PANI composite films.

Assembly of potassium niobate nanosheets/silver oxide composite films with good SERS performance towards crystal violet detection

NASA Astrophysics Data System (ADS)

Zhu, Kun; Hong, Zhen; Kang, Shi-Zhao; Qin, Lixia; Li, Guodong; Li, Xiangqing

2018-04-01

The orderly potassium niobate nanosheets/silver oxide (Ag2O) composite films with uniform morphology were achieved by layer-by-layer self-assembly combined with ultraviolet light irradiation. The composition, structure and morphology of the potassium niobate nanosheets/Ag2O composite films were studied by XPS, XRD and SEM. Furthermore, the films were used as a SERS probe to detect crystal violet molecules. The results showed that the potassium niobate nanosheets/Ag2O composite films were an active substrate for fast and sensitive detection of crystal violet with low concentration. The limit of detection by the films can reach 1 × 10-6 mol L-1. Both electromagnetic enhancement and chemical enhancement contributed to the enhanced SERS in the (potassium niobate nanosheets/Ag2O)4 films. Moreover, it was found that the films were relatively stable under light irradiation or heat treatment in a certain range.

A novel design of anode-supported solid oxide fuel cells with Y 2O 3-doped Bi 2O 3, LaGaO 3 and La-doped CeO 2 trilayer electrolyte

NASA Astrophysics Data System (ADS)

Guo, Weimin; Liu, Jiang

Anode-supported solid oxide fuel cells (SOFCs) with a trilayered yttria-doped bismuth oxide (YDB), strontium- and magnesium-doped lanthanum gallate (LSGM) and lanthanum-doped ceria (LDC) composite electrolyte film are developed. The cell with a YDB (18 μm)/LSGM (19 μm)/LDC (13 μm) composite electrolyte film (designated as cell-A) shows the open-circuit voltages (OCVs) slightly higher than that of a cell with an LSGM (31 μm)/LDC (17 μm) electrolyte film (designated as cell-B) in the operating temperature range of 500-700 °C. The cell-A using Ag-YDB composition as cathode exhibits lower polarization resistance and ohmic resistance than those of a cell-B at 700 °C. The results show that the introduction of YDB to an anode-supported SOFC with a LSGM/LDC composite electrolyte film can effectively block electronic transport through the cell and thus increased the OCVs, and can help the cell to achieve higher power output.

Preparation and Characterization of Composites Based on Polylactic Acid and Beeswax with Improved Water Vapor Barrier Properties.

PubMed

Lim, Jung Hoon; Kim, Jeong Ae; Ko, Jung A; Park, Hyun Jin

2015-11-01

Beeswax and a plasticizer (ATBC) were added to polylactic acid (PLA) films in order to enhance the water vapor barrier properties of the films. Beeswax improved the barrier properties; the water vapor permeability in the composite containing 1% beeswax was 58% lower than that of the neat PLA. Fourier transform infrared spectroscopy and X-ray diffraction analysis revealed that the incorporation of beeswax and ATBC had so little effect on the PLA structure. In addition, the structure of PLA did not vary substantially with the additions. The surfaces of the composites were examined by using field emission scanning electron microscopy. Differential scanning calorimetry results showed that the degree of crystallinity of the PLA films increased with the addition of beeswax and ATBC. However, the tensile strength and elongation at break of the composites containing beeswax were up to approximately 50% lower than those of the neat PLA. Although further study is needed to improve the mechanical properties, the aforementioned results showed that the PLA barrier properties can be improved by the incorporation of a small amount of beeswax and ATBC. The results of this study can be applied for the preparation of PLA composite films with improved barrier properties. Such biodegradable films are extremely useful for applications in the food packaging industry. © 2015 Institute of Food Technologists®

Combinatorial investigation of Fe–B thin-film nanocomposites

PubMed Central

Brunken, Hayo; Grochla, Dario; Savan, Alan; Kieschnick, Michael; Meijer, Jan D; Ludwig, Alfred

2011-01-01

Combinatorial magnetron sputter deposition from elemental targets was used to create Fe–B composition spread type thin film materials libraries on thermally oxidized 4-in. Si wafers. The materials libraries consisting of wedge-type multilayer thin films were annealed at 500 or 700 °C to transform the multilayers into multiphase alloys. The libraries were characterized by nuclear reaction analysis, Rutherford backscattering, nanoindentation, vibrating sample magnetometry, x-ray diffraction (XRD) and transmission electron microscopy (TEM). Young's modulus and hardness values were related to the annealing parameters, structure and composition of the films. The magnetic properties of the films were improved by annealing in a H2 atmosphere, showing a more than tenfold decrease in the coercive field values in comparison to those of the vacuum-annealed films. The hardness values increased from 8 to 18 GPa when the annealing temperature was increased from 500 to 700 °C. The appearance of Fe2B phases, as revealed by XRD and TEM, had a significant effect on the mechanical properties of the films. PMID:27877435

Deposition and composition-control of Mn-doped ZnO thin films by combinatorial pulsed laser deposition using two delayed plasma plumes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanchez-Ake, C.; Camacho, R.; Moreno, L.

2012-08-15

Thin films of ZnO doped with manganese were deposited by double-beam, combinatorial pulsed laser deposition. The laser-induced plasmas were studied by means of fast photography and using a Langmuir probe, whereas the films were analyzed by x-ray-diffraction and energy-dispersive x-ray spectroscopy. The effect of the relative delay between plasma plumes on the characteristics of the films was analyzed. It was found that using this parameter, it is possible to control the dopant content keeping the oriented wurtzite structure of the films. The minimum content of Mn was found for plume delays between 0 and 10 {mu}s as the interaction betweenmore » plasmas scatters the dopant species away from the substrate, thus reducing the incorporation of Mn into the films. Results suggest that for delays shorter than {approx}100 {mu}s, the expansion of the second plume through the region behind the first plume affects the composition of the film.« less

Morphology, composition and electrical properties of SnO{sub 2}:Cl thin films grown by atomic layer deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Hsyi-En, E-mail: sean@mail.stust.edu.tw; Wen, Chia-Hui; Hsu, Ching-Ming

2016-01-15

Chlorine doped SnO{sub 2} thin films were prepared using atomic layer deposition at temperatures between 300 and 450 °C using SnCl{sub 4} and H{sub 2}O as the reactants. Composition, structure, surface morphology, and electrical properties of the as-deposited films were examined. Results showed that the as-deposited SnO{sub 2} films all exhibited rutile structure with [O]/[Sn] ratios between 1.35 and 1.40. The electrical conductivity was found independent on [O]/[Sn] ratio but dependent on chlorine doping concentration, grain size, and surface morphology. The 300 °C-deposited film performed a higher electrical conductivity of 315 S/cm due to its higher chlorine doping level, larger grain size, andmore » smoother film surface. The existence of Sn{sup 2+} oxidation state was demonstrated to minimize the effects of chlorine on raising the electrical conductivity of films.« less

Influence of functional group on the electrical transport properties of polyvinyl alcohol grafted multiwall carbon nanotube composite thick film

NASA Astrophysics Data System (ADS)

Kumar Das, Amit; Dharmana, Reuben; Mukherjee, Ayan; Baba, Koumei; Hatada, Ruriko; Kumar Meikap, Ajit

2018-04-01

We present a novel technique to obtain a higher or lower value of dielectric constant due to the variation of a functional group on the surface of multiwall carbon nanotube (MWCNTs) for a polyvinyl alcohol (PVA) grafted MWCNT system. We have prepared PVA grafted pristine and different types of functionalized (-COOH, -OH, and -NH2) MWCNT nanocomposite films. The strong interfacial interaction between the host PVA matrix and nanofiller is characterized by different experimental techniques. The frequency variation of the electrical transport properties of the composite films is investigated in a wide temperature range (303 ≤ T ≤ 413 K) and frequency range (20 Hz ≤ f ≤ 1 MHz). The dielectric constant of the amine (-NH2) functionalized MWCNT incorporated PVA film is about 2 times higher than that of the pristine MWCNT embedded PVA film. The temperature variation of the dielectric constant shows an anomalous behaviour. The modified Cole-Cole equation simulated the experimentally observed dielectric spectroscopy at high temperature. The ac conductivity of the composite films obeys the correlated barrier hopping model. The imaginary part of the electric modulus study shows the ideal Debye-type behaviour at low frequency and deviation of that at high frequency. To illustrate the impedance spectroscopy of the nanocomposite films, we have proposed an impedance based battery equivalent circuit model. The current-voltage characteristic shows hysteresis behaviour of the nanocomposite films. The trap state height for all composite films is evaluated by simulating the current density-electric field data with the Poole-Frenkel emission model. This investigation opens a new avenue for designing electronic devices with a suitable combination of cost effective soft materials.

Temperature effects on polymer-carbon composite sensors: evaluating the role of polymer molecular weight and carbon loading

NASA Technical Reports Server (NTRS)

Homer, M. L.; Lim, J. R.; Manatt, K.; Kisor, A.; Lara, L.; Jewell, A. D.; Yen, S. -P. S.; Shevade, A. V.; Ryan, M. A.

2003-01-01

We report the effect of environmental condtions coupled with varying polymer properties and carbon loadings on the performance of polymer-carbon black composite film, used as sensing medium in the JPL Electronic Nose.

Transparent sunlight conversion film based on carboxymethyl cellulose and carbon dots.

PubMed

You, Yaqin; Zhang, Haoran; Liu, Yingliang; Lei, Bingfu

2016-10-20

Transparent sunlight conversion film based on carboxymethyl cellulose (CMC) and carbon dots (CDs) has been developed for the first time through dispersion of CDs in CMC aqueous solution. Due to the hydrogen bonds interaction, CMC can effectively absorb the CDs, whose surfaces are functionalized by lots of polar groups. The results from atomic force microscopy (AFM), scanning electron microscopy (SEM) confirm that the composite film possesses a homogeneous and compact structure. Besides, the CMC matrix neither competes for absorbing excitation light nor absorbs the emissions of CDs, which reserves the inherent optical properties of the individual CDs. The composite films can efficiently convert ultraviolet light to blue light. What's more, the film is transparent and possesses excellent mechanical properties, expected to apply in the field of agricultural planting for sunlight conversion. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of Sb on physical properties and microstructures of laser nano/amorphous-composite film

NASA Astrophysics Data System (ADS)

Li, Jia-Ning; Gong, Shui-Li; Sun, Mei; Shan, Fei-Hu; Wang, Xi-Chang; Jiang, Shuai

2013-11-01

A nano/amorphous-composite film was fabricated by laser cladding (LC) of the Co-Ti-B4C-Sb mixed powders on a TA15 alloy. Such film mainly consisted of Ti-Al, Co-Ti, Co-Sb intermetallics, TiC, TiB2, TiB, and the amorphous phases. Experimental results indicated that the crystal systems of TiB2 (hexagonal)/TiC (cubic) and Sb (rhombohedral) played important role on the formation of such film. Due to the mismatch of these crystals systems and mutual immiscibility of the metallic components, Sb was not incorporated in TiB2/TiC, but formed separate nuclei during the film growth. Thus, the growth of TiB2/TiC was stopped by the Sb nucleus in such LC molten pool, so as to form the nanoscale particles.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajachidambaram, Jaana Saranya; Sanghavi, Shail P.; Nachimuthu, Ponnusamy

Amorphous zinc tin oxide (ZTO) was investigated to determine the effect of deposition and post annealing conditions on film structure, composition, surface contamination, and thin film transistor (TFT) device performance. X-ray diffraction results indicated that the ZTO films remain amorphous even after annealing to 600 °C. We found that the bulk Zn:Sn ratio of the sputter deposited films were slightly tin rich compared to the composition of the ceramic sputter target, and there was a significant depletion of zinc at the surface. X-ray photoelectron spectroscopy also indicated that residual surface contamination depended strongly on the sample post-annealing conditions where water,more » carbonate and hydroxyl species were absorbed to the surface. Electrical characterization of ZTO films, using TFT test structures, indicated that mobilities as high as 17 cm2/Vs could be obtained for depletion mode devices.« less

Solution-Processed VO2-SiO2 Composite Films with Simultaneously Enhanced Luminous Transmittance, Solar Modulation Ability and Anti-Oxidation property

PubMed Central

Zhao, Lili; Miao, Lei; Liu, Chengyan; Li, Chao; Asaka, Toru; Kang, Yipu; Iwamoto, Yuji; Tanemura, Sakae; Gu, Hui; Su, Huirong

2014-01-01

Recently, researchers spare no efforts to fabricate desirable vanadium dioxide (VO2) film which provides simultaneously high luminous transmittance and outstanding solar modulation ability, yet progress towards the optimization of one aspect always comes at the expense of the other. Our research devotes to finding a reproducible economic solution-processed strategy for fabricating VO2-SiO2 composite films, with the aim of boosting the performance of both aspects. Compare to VO2 film, an improvement of 18.9% (from 29.6% to 48.5%) in the luminous transmittance as well as an increase of 6.0% (from 9.7% to 15.7%) in solar modulation efficiency is achieved when the molar ratio of Si/V attains 0.8. Based on the effective medium theory, we simulate the optical spectra of the composite films and the best thermochromic property is obtained when the filling factor attains 0.5, which is consistent with the experimental results. Meanwhile, the improvement of chemical stability for the composite film against oxidation has been confirmed. Tungsten is introduced to reduce the phase transition temperature to the ambient temperature, while maintain the thermochromism required for application as smart window. Our research set forth a new avenue in promoting practical applications of VO2-based thermochromic fenestration. PMID:25384345

Solution-Processed VO2-SiO2 Composite Films with Simultaneously Enhanced Luminous Transmittance, Solar Modulation Ability and Anti-Oxidation property

NASA Astrophysics Data System (ADS)

Zhao, Lili; Miao, Lei; Liu, Chengyan; Li, Chao; Asaka, Toru; Kang, Yipu; Iwamoto, Yuji; Tanemura, Sakae; Gu, Hui; Su, Huirong

2014-11-01

Recently, researchers spare no efforts to fabricate desirable vanadium dioxide (VO2) film which provides simultaneously high luminous transmittance and outstanding solar modulation ability, yet progress towards the optimization of one aspect always comes at the expense of the other. Our research devotes to finding a reproducible economic solution-processed strategy for fabricating VO2-SiO2 composite films, with the aim of boosting the performance of both aspects. Compare to VO2 film, an improvement of 18.9% (from 29.6% to 48.5%) in the luminous transmittance as well as an increase of 6.0% (from 9.7% to 15.7%) in solar modulation efficiency is achieved when the molar ratio of Si/V attains 0.8. Based on the effective medium theory, we simulate the optical spectra of the composite films and the best thermochromic property is obtained when the filling factor attains 0.5, which is consistent with the experimental results. Meanwhile, the improvement of chemical stability for the composite film against oxidation has been confirmed. Tungsten is introduced to reduce the phase transition temperature to the ambient temperature, while maintain the thermochromism required for application as smart window. Our research set forth a new avenue in promoting practical applications of VO2-based thermochromic fenestration.

Sandwich-Architectured Poly(lactic acid)-Graphene Composite Food Packaging Films.

PubMed

Goh, Kunli; Heising, Jenneke K; Yuan, Yang; Karahan, Huseyin E; Wei, Li; Zhai, Shengli; Koh, Jia-Xuan; Htin, Nanda M; Zhang, Feimo; Wang, Rong; Fane, Anthony G; Dekker, Matthijs; Dehghani, Fariba; Chen, Yuan

2016-04-20

Biodegradable food packaging promises a more sustainable future. Among the many different biopolymers used, poly(lactic acid) (PLA) possesses the good mechanical property and cost-effectiveness necessary of a biodegradable food packaging. However, PLA food packaging suffers from poor water vapor and oxygen barrier properties compared to many petroleum-derived ones. A key challenge is, therefore, to simultaneously enhance both the water vapor and oxygen barrier properties of the PLA food packaging. To address this issue, we design a sandwich-architectured PLA-graphene composite film, which utilizes an impermeable reduced graphene oxide (rGO) as the core barrier and commercial PLA films as the outer protective encapsulation. The synergy between the barrier and the protective encapsulation results in a significant 87.6% reduction in the water vapor permeability. At the same time, the oxygen permeability is reduced by two orders of magnitude when evaluated under both dry and humid conditions. The excellent barrier properties can be attributed to the compact lamellar microstructure and the hydrophobicity of the rGO core barrier. Mechanistic analysis shows that the large rGO lateral dimension and the small interlayer spacing between the rGO sheets have created an extensive and tortuous diffusion pathway, which is up to 1450-times the thickness of the rGO barrier. In addition, the sandwiched architecture has imbued the PLA-rGO composite film with good processability, which increases the manageability of the film and its competency to be tailored. Simulations using the PLA-rGO composite food packaging film for edible oil and potato chips also exhibit at least eight-fold extension in the shelf life of these oxygen and moisture sensitive food products. Overall, these qualities have demonstrated the high potential of a sandwich-architectured PLA-graphene composite film for food packaging applications.

Fabrication of efficient graphene-doped polymer/fullerene bilayer organic solar cells in air using spin coating followed by ultrasonic vibration post treatment

NASA Astrophysics Data System (ADS)

Zabihi, Fatemeh; Chen, Qianli; Xie, Yu; Eslamian, Morteza

2016-12-01

In this work, in an attempt to improve the performance and lifetime of organic solar cells, P3HT photon absorbing polymer was doped with graphene (G) nano-sheets, to make light harvesting G-P3HT composite thin film. The composite this film was then employed as the donor of a bilayer organic solar cell with the structure of glass/ITO/PEDOT:PSS/G-P3HT/C60/Al. The reference P3HT:PCBM bulk heterojunction solar cell was also fabricated for comparison. All solution-processed layers were made by spin coating in humid air (Shanghai, China); C60 and Al were deposited by thermal evaporation. An effective mechanical treatment approach developed by the authors, i.e. the application of forced ultrasonic vibration on the wet spun-on films, was used to improve the dispersion of graphene in G-P3HT composite films to obtain a uniform nanostructure. This mechanical method eliminates tedious and expensive chemical steps, currently performed to engineer the structure of organic solar cells. It is evidenced that the G-P3HT composite thin films, post treated by ultrasonic vibration at the optimum vibration duration, possess superior electrical conductivity, charge carrier mobility and density, uniform surface potential distribution, and lower surface roughness, compared to those of P3HT and G-P3HT thin films made without vibration. The results show significant improvement in the power conversion efficiency (PCE) of vibration-treated G-P3HT/C60 cell (PCE = 5.17%, the highest reported for this structure), substantiating the strong positive effect of using graphene and forced vibration for the fabrication of P3HT active layer in the bilayer cell structure.

Polyethylene Films Containing Silver Nanoparticles for Applications in Food Packaging: Characterization of Physico-Chemical and Anti-Microbial Properties.

PubMed

Becaro, Aline A; Puti, Fernanda C; Correa, Daniel S; Paris, Elaine C; Marconcini, José M; Ferreira, Marcos D

2015-03-01

This paper reports the antibacterial effect and physico-chemical characterization of films containing silver nanoparticles for use as food packaging. Two masterbatches (named PEN and PEC) con- taining silver nanoparticles embedded in distinct carriers (silica and titanium dioxide) were mixed with low-density polyethylene (LDPE) in different compositions and extruded to produce plain films. These films were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA) and Fourier Transform Infrared Spectroscopy (FTIR). The morphology of the films showed the formation of agglomerates of nanoparticles in both PEN and PEC composites. X-ray analyses confirmed the presence of SiO2 in PEN samples and TiO2 in PEC samples. Thermal analyses indicated an increase in thermal stability of the PEC compositions. The antimicrobial efficacy was determined by applying the test strain for Escherichia coli and Staphylococcus aureus, according to the Japanese Industrial Standard Method (JIS Z 2801:2000). The films analyzed showed antimicrobial properties against the tested microorganisms, presenting better activity against the S. aureus than E. Coli. These findings suggest that LDPE films with silver nanoparticles are promising to provide a significant contribution to the quality and safety of packaged food.

Film Delivery Module For Fiber Placement Fabrication of Hybridized Composite Structures

NASA Technical Reports Server (NTRS)

Hulcher, Anthony Bruce; Young, Greg

2005-01-01

A new fabrication technology has been developed at the NASA Marshall Space Flight Center that will allow for the fabrication of hybridized composite structures using fiber placement processing. This technology was originally developed in response to a need to address the issue of hydrogen permeation and microcracking in cryogenic propellant tanks. Numerous thin polymeric and metallized films were investigated under low temperatures conditions for use as barrier films in a composite tank. Manufacturing studies conducted at that time did not address the processing issues related to fabrication of a hybridized tank wall. A film processing head was developed that will allow for the processing of thin polymeric and metallized films, metallic foils, and adhesives using fiber placement processing machinery. The film head is designed to enable the simultaneous processing of film materials and composite tape/tow during the composite part layup process and is also capable of processing the film during an independent operation. Several initial demonstrations were conducted to assess the performance of the film module device. Such assessments included film strip lay-up accuracy, capability to fabricate panels having internal film liners, and fabrication of laminates with embedded film layers.

Effects of propagational factors on quantum wires in close parallel proximity

NASA Astrophysics Data System (ADS)

Wilson, David A.

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Investigation of the influence of the composition on mechanical properties poly(glycolide-DL-lactide)

NASA Astrophysics Data System (ADS)

Baikin, A. S.; Sevostyanov, M. A.; Nasakina, E. O.; Sergienko, K. V.; Kaplan, M. A.; Konushkin, S. V.; Kolmakova, A. A.; Yakubov, A. D.; Kolmakov, A. G.

2018-04-01

In this paper we describe the creation of films from poly (glycolide-DL-lactide). Studied the mechanical properties of developed polymer films of poly (glycolide-DL-lactide). The effect of the molecular weight of poly (glycolide-DL-lactide) on the mechanical properties of the resulting polymer films is shown. The dependence of the mechanical properties of poly (glycolide-DL-lactide) films on the polymer concentration in chloroform was studied. The possibility of creating biodegradable films with specified mechanical properties is shown.

Composite materials obtained by the ion-plasma sputtering of metal compound coatings on polymer films

NASA Astrophysics Data System (ADS)

Khlebnikov, Nikolai; Polyakov, Evgenii; Borisov, Sergei; Barashev, Nikolai; Biramov, Emir; Maltceva, Anastasia; Vereshchagin, Artem; Khartov, Stas; Voronin, Anton

2016-01-01

In this article, the principle and examples composite materials obtained by deposition of metal compound coatings on polymer film substrates by the ion-plasma sputtering method are presented. A synergistic effect is to obtain the materials with structural properties of the polymer substrate and the surface properties of the metal deposited coatings. The technology of sputtering of TiN coatings of various thicknesses on polyethylene terephthalate films is discussed. The obtained composites are characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and scanning tunneling microscopy (STM) is shown. The examples of application of this method, such as receiving nanocomposite track membranes and flexible transparent electrodes, are considered.

The Use of OXYGEN-18 in the Development of Methods for Controlled Sputter Deposition of High Critical Transition Temperature Material Thin Films of Predicted Composition and Good Uniformity

NASA Astrophysics Data System (ADS)

Tidrow, Steven Clay

Two primary concerns, in the sputter deposition of high T_{c} material films, are the prevention of oxygen deficiency in the films and the elimination of the negative ion effect. "Oxygen deficiency" occurs when the amount of oxygen incorporated into the film is less than the amount of oxygen required to form the superconducting material lattice. Oxygen deficiency is due to the volatile nature of oxygen. The negative ion effect occurs when an atom or molecule (typically oxygen) gains an extra electron, is accelerated away from the target and impinges upon a film being grown directly in front of the sputtering target. The impinging particle has enough energy to cause resputtering of the deposited film. The presence of Sr and to a greater extent Ba, may enhance the negative ion effect in these materials. However, it is oxygen which readily forms negative ions that is primarily responsible for the negative ion effect. Thus, oxygen must be given special attention in the sputter deposition of high T_{c} material films. A specially designed sputtering system is used to demonstrate that the negative ion effect can be reduced such that large uniform high T_{c} material films possessing predicted and repeated composition can be grown in an on-axis arrangement. Utilizing this same sputtering system and the volatile nature of oxygen, it is demonstrated that oxygen processes occurring in the chamber during growth of high T_ {c} material films can be investigated using the tracer ^{18}O. In particular, it is shown that ^{18}O can be utilized as a tool for (1) investigating the negative ion effect, (2) investigating oxygen incorporation into high T_{c} material films, (3) investigating oxygen incorporation into the target, (4) tailoring films for oxygen migration and interface investigations and (5) tailoring films for the other specific oxygen investigations. Such sputtering systems that utilize the tracer ^{18}O are necessary for systematic growth of high T_ {c} material films for systematic investigations into the nature of these materials.

Enhanced off-resonance magnetoelectric response in laser annealed PZT thick film grown on magnetostrictive amorphous metal substrate

NASA Astrophysics Data System (ADS)

Palneedi, Haribabu; Maurya, Deepam; Kim, Gi-Yeop; Priya, Shashank; Kang, Suk-Joong L.; Kim, Kwang-Ho; Choi, Si-Young; Ryu, Jungho

2015-07-01

A highly dense, 4 μm-thick Pb(Zr,Ti)O3 (PZT) film is deposited on amorphous magnetostrictive Metglas foil (FeBSi) by granule spray in vacuum process at room temperature, followed by its localized annealing with a continuous-wave 560 nm ytterbium fiber laser radiation. This longer-wavelength laser radiation is able to anneal the whole of thick PZT film layer without any deteriorative effects, such as chemical reaction and/or atomic diffusion, at the interface and crystallization of amorphous Metglas substrate. Greatly enhanced dielectric and ferroelectric properties of the annealed PZT are attributed to its better crystallinity and grain growth induced by laser irradiation. As a result, a colossal off-resonance magnetoelectric (ME) voltage coefficient that is two orders of magnitude larger than previously reported output from PZT/Metglas film-composites is achieved. The present work addresses the problems involved in the fabrication of PZT/Metglas film-composites and opens up emerging possibilities in employing piezoelectric materials with low thermal budget substrates (suitable for integrated electronics) and designing laminate composites for ME based devices.

Fluorine-containing composition for forming anti-reflection film on resist surface and pattern formation method

DOEpatents

Nishi, Mineo; Makishima, Hideo

1996-01-01

A composition for forming anti-reflection film on resist surface which comprises an aqueous solution of a water soluble fluorine compound, and a pattern formation method which comprises the steps of coating a photoresist composition on a substrate; coating the above-mentioned composition for forming anti-reflection film; exposing the coated film to form a specific pattern; and developing the photoresist, are provided. Since the composition for forming anti-reflection film can be coated on the photoresist in the form of an aqueous solution, not only the anti-reflection film can be formed easily, but also, the film can be removed easily by rinsing with water or alkali development. Therefore, by the pattern formation method according to the present invention, it is possible to form a pattern easily with a high dimensional accuracy.

Preparation and biocompatibility of a chitin nanofiber/gelatin composite film.

PubMed

Ogawa, Yoko; Azuma, Kazuo; Izawa, Hironori; Morimoto, Minoru; Ochi, Kosuke; Osaki, Tomohiro; Ito, Norihiko; Okamoto, Yoshiharu; Saimoto, Hiroyuki; Ifuku, Shinsuke

2017-11-01

The development of chitin-based materials with favorable mechanical properties and biocompatibility is an important research goal owing to the wide-ranging practical applications. In this study, a composite film was prepared using chitin nanofibers and gelatin. The CNF/gelatin composite film was highly viscous and had a fine nanofiber structure. The transmittances indicated high transparency, regardless of nanofiber content. The water content of the CNF/gelatin composite film increased linearly as the gelatin content increased. Although the CNF/gelatin composite film did not induce severe inflammation, it strongly induced fibroblast proliferation, indicating high biocompatibility. Based on these results, the films are suitable for biological applications, e.g., tissue engineering, medicines, and cosmetics. Copyright © 2017 Elsevier B.V. All rights reserved.

Fabrication of graphene/polyaniline composite multilayer films by electrostatic layer-by-layer assembly

NASA Astrophysics Data System (ADS)

Cong, Jiaojiao; Chen, Yuze; Luo, Jing; Liu, Xiaoya

2014-10-01

A novel graphene/polyaniline composite multilayer film was fabricated by electrostatic interactions induced layer-by-layer self-assembly technique, using water dispersible and negatively charged chemically converted graphene (CCG) and positively charged polyaniline (PANI) as building blocks. CCG was achieved through partly reduced graphene oxide, which remained carboxyl group on its surface. The remaining carboxyl groups not only retain the dispersibility of CCG, but also allow the growth of the multilayer films via electrostatic interactions between graphene and PANI. The structure and morphology of the obtained CCG/PANI multilayer film are characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, Ultraviolet-visible absorption spectrum (UV-vis), scanning electron microscopy (SEM), Raman spectroscopy and X-Ray Diffraction (XRD). The electrochemical properties of the resulting film are studied using cyclic voltammetry (CV), which showed that the resulting CCG/PANI multilayer film kept electroactivity in neutral solution and showed outstanding cyclic stability up to 100 cycles. Furthermore, the composite film exhibited good electrocatalytic ability toward ascorbic acid (AA) with a linear response from 1×10-4 to 1.2×10-3 M with the detect limit of 5×10-6 M. This study provides a facile and effective strategy to fabricate graphene/PANI nanocomposite film with good electrochemical property, which may find potential applications in electronic devices such as electrochemical sensor.

Synthesis, characterization, and light-controlled antibiotic application of a composite material derived from polyurethane and silica xerogel with embedded photoactive manganese nitrosyl.

PubMed

Heilman, Brandon J; Halpenny, Genevieve M; Mascharak, Pradip K

2011-11-01

The synthesis of a light-sensitive polyurethane-based composite material (PUX-NO) is described. In its polyurethane medium, PUX-NO contains entrapped silica xerogel particles in which a photoactive manganese nitrosyl has been incorporated. Green flexible films of PUX-NO readily release nitric oxide (NO) only when exposed to low power (mW) visible light. Incorporation of the nitrosyl in the xerogel not only retains the nitrosyl (NO donor) within the composite material but also provides the right extent of hydration. Pre-swelled films of PUX-NO have water content close to 30 Wt % and such films can be stored for months under slightly moist condition without loss in NO-delivering capacity. The NO-releasing parameters of the film have been determined. The NO-releasing capacity of PUX-NO films can be conveniently altered by changing the amount of the nitrosyl as well as the thickness of the films. Patches of PUX-NO film have been successfully employed to reduce drastically bacterial loads of both gram-positive and gram-negative bacteria including methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii under the total control of light. Effective control of infections by these bacterial pathogens via delivery of proper doses of NO only to the sites of infection appears feasible with PUX-NO films. 2011 Wiley Periodicals, Inc.

Thermal dewetting behavior of polystyrene composite thin films with organic-modified inorganic nanoparticles.

PubMed

Kubo, Masaki; Takahashi, Yosuke; Fujii, Takeshi; Liu, Yang; Sugioka, Ken-ichi; Tsukada, Takao; Minami, Kimitaka; Adschiri, Tadafumi

2014-07-29

The thermal dewetting of polystyrene composite thin films with oleic acid-modified CeO2 nanoparticles prepared by the supercritical hydrothermal synthesis method was investigated, varying the nanoparticle concentration (0-30 wt %), film thickness (approximately 50 and 100 nm), and surface energy of silanized silicon substrates on which the composite films were coated. The dewetting behavior of the composite thin films during thermal annealing was observed by an optical microscope. The presence of nanoparticles in the films affected the morphology of dewetting holes, and moreover suppressed the dewetting itself when the concentration was relatively high. It was revealed that there was a critical value of the surface energy of the substrate at which the dewetting occurred. In addition, the spatial distributions of nanoparticles in the composite thin films before thermal annealing were investigated using AFM and TEM. As a result, we found that most of nanoparticles segregated to the surface of the film, and that such distributions of nanoparticles contribute to the stabilization of the films, by calculating the interfacial potential of the films with nanoparticles.

Excellent vacuum tribological properties of Pb/PbS film deposited by RF magnetron sputtering and ion sulfurizing.

PubMed

Guozheng, Ma; Binshi, Xu; Haidou, Wang; Shuying, Chen; Zhiguo, Xing

2014-01-08

Soft metal Pb film of 3 μm in thickness was deposited on AISI 440C steel by RF magnetron sputtering, and then some of the Pb film samples were treated by low-temperature ion sulfurizing (LTIS) and formed Pb/PbS composite film. Tribological properties of the Pb and Pb/PbS films were tested contrastively in vacuum and air condition using a self-developed tribometer (model of MSTS-1). Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were adopted to analyze the microstructure and chemical construction of the films and their worn surfaces. The results show that a mass of Pb was changed to PbS during the process of LTIS. In air condition, owing to the severe oxidation effect, pure Pb film showed relatively high friction coefficients (0.6), and Pb/PbS composite film also lost its friction-reduction property after sliding for a short time. In a vacuum, the average friction coefficients of Pb film were about 0.1, but the friction coefficient curve fluctuated obviously. And the Pb/PbS composite film exhibited excellent tribological properties in vacuum condition. Its friction coefficients keep stable at a low value of about 0.07 for a long time. If takes the value of friction coefficients exceeding 0.2 continuously as a criterion of lubrication failure, the sliding friction life of Pb/PbS film was as long as 3.2 × 10(5) r, which is 8 times of that of the Pb film. It can be concluded that the Pb/PbS film has excellent vacuum tribological properties and important foreground for applying in space solid lubrication related fields.

Processing effects on the microstructure and dielectric properties of hydrothermal barium titanate and (barium,strontium)titanate thin films

NASA Astrophysics Data System (ADS)

McCormick, Mark Alan

The goal of this work was to produce BaTiO3 and BaxSr (1-x)TiO3 (BST) thin films with high dielectric constants, using a low-temperature (<100°C) hydrothermal synthesis route. To accomplish this, titanium metal-organic precursor films were spin-cast onto metal-coated glass substrates and converted to polycrystalline BaTiO3 or BST upon reacting in aqueous solutions of Ba(OH)2 or Ba(OH)2 and Sr(OH)2. The influences of solution molarity, processing temperature, and reaction time on thin film reaction kinetics, microstructure, and dielectric properties were examined for BaTiO3 films. Post-deposition annealing at temperatures as low as 200°C substantially affected the lattice parameter, dielectric constant, and dielectric loss. This behavior is explained in terms of hydroxyl defect incorporation during film formation. Current-voltage (I-V) measurements were performed to determine the dominant conduction mechanism(s) during application of a do field, and to extract the metal/ceramic barrier height. In particular, Schottky barrier-limited conduction and Poole-Frenkel conduction were investigated as potential leakage mechanisms. For BST thin films, film stoichiometry deviated from the initial solution composition, with a preferred incorporation of Sr2+ into the perovskite lattice. The dielectric constant of the BST films was measured as a function of composition (Ba:Sr ratio) and temperature over the range 25--150°C. Finally, capacitance-voltage (C-V) measurements were made for BST films to determine the influence of film composition on dielectric tunability.

Synthesis and characterization of nanosilver-silicone hydrogel composites for inhibition of bacteria growth.

PubMed

Helaly, F M; El-Sawy, S M; Hashem, A I; Khattab, A A; Mourad, R M

2017-02-01

Nanosilver-silicone hydrogel (NAgSiH) composites for contact lenses were synthesized to asses the antimicrobial effects. Silicone hydrogel (SiH) films were synthesized followed by impregnation in silver nitrate solutions (10, 20, 30, 40, 60, 80ppm) and in-situ chemical reduction of silver ions using sodium borohydride (NaBH 4 ). The silver nano particles (AgNPS) were identified by UV-vis absorption spectroscopy, Energy-dispersive X-ray spectroscopy (EDX) mapping and EDX spectrum. Physico-mechanical and chemical properties of NAgSIH films were studied. The antimicrobial effect of the hydrogels against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus was evaluated. The numbers of viable bacterial cells on NAgSiH surface or in solution compared to control SiH were examined. The NAgSiH films were successfully synthesized. FTIR results indicated that AgNPS had no effect on the bulk structure of the prepared SiH films. From TGA analysis, NAgSiH(R80) and SiH(R0) films had the same maximum decomposition temperature (404°C). UV-vis absorption spectroscopy and EDX mapping and spectrum emphasized that AgNPS were in spherical shape. The maximum absorption wavelength of NAgSiH films were around 400nm. The light transmittance decreased as the concentration of AgNPS increased, but still greater than 90% at wavelength around 555nm. The Young's modulus increased gradually from 1.06MPa of SiH(R0) to highest value 1.38MPa of NAgSiH(R80). AgNPS incorporated into SiH films reduced the bacterial cell growth and prevented colonization. Groups NAgSiH(R60,R80) demonstrated an excellent reduction in bacterial viability in solution and on the SiH surface. NAgSiH composites were successfully synthesized and possessed an excellent antimicrobial effects. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Effect of additional elements on compositional modulated atomic layered structure of hexagonal Co{sub 80}Pt{sub 20} alloy films with superlattice diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinata, Shintaro; Research Fellowship Division Japan Society for the Promotion of Science; Yamane, Akira

2016-05-15

The effect of additional element on compositionally modulated atomic layered structure of hexagonal Co{sub 80}Pt{sub 20} alloy films with superlattice diffraction was investigated. In this study it is found that the addition of Cr or W element to Co{sub 80}Pt{sub 20} alloy film shows less deterioration of hcp stacking structure and compositionally modulated atomic layer stacking structure as compared to Si or Zr or Ti with K{sub u} of around 1.4 or 1.0 × 10{sup 7} erg/cm{sup 3} at 5 at.% addition. Furthermore, for O{sub 2} addition of O{sub 2} ≥ 5.0 × 10{sup −3} Pa to CoPt alloy, compositionallymore » modulated atomic layer stacking structure will be deteriorated with enhancement of formation of hcp stacking structure which leads higher K{sub u} of 1.0 × 10{sup 7} erg/cm{sup 3}.« less

Influence of Thin-Film Adhesives in Pullout Tests Between Nickel-Titanium Shape Memory Alloy and Carbon Fiber-Reinforced Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Quade, Derek J.; Jana, Sadhan; McCorkle, Linda S.

2018-01-01

Strips of nickel-titanium (NiTi) shape memory alloy (SMA) and carbon fiber-reinforced polymer matrix composite (PMC) were bonded together using multiple thin film adhesives and their mechanical strengths were evaluated under pullout test configuration. Tensile and lap shear tests were conducted to confirm the deformation of SMAs at room temperature and to evaluate the adhesive strength between the NiTi strips and the PMC. Optical and scanning electron microscopy techniques were used to examine the interfacial bonding after failure. Simple equations on composite tensile elongation were used to fit the experimental data on tensile properties. ABAQUS models were generated to show the effects of enhanced bond strength and the distribution of stress in SMA and PMC. The results revealed that the addition of thin film adhesives increased the average adhesive strength between SMA and PMC while halting the room temperature shape memory effect within the pullout specimen.

Model Amphiphilic Block Copolymers with Tailored Molecular Weight and Composition in PDMS-Based Films to Limit Soft Biofouling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wenning, Brandon M.; Martinelli, Elisa; Mieszkin, Sophie

A set of controlled surface composition films was produced utilizing amphiphilic block copolymers dispersed in a cross-linked poly(dimethylsiloxane) network. These block copolymers contained oligo(ethylene glycol) (PEGMA) and fluoroalkyl (AF6) side chains in selected ratios and molecular weights to control surface chemistry including antifouling and fouling-release performance. Such properties were assessed by carrying out assays using two algae, the green macroalga Ulva linza (favors attachment to polar surfaces) and the unicellular diatom Navicula incerta (favors attachment to nonpolar surfaces). All films performed well against U. linza and exhibited high removal of attached sporelings (young plants) under an applied shear stress, withmore » the lower molecular weight block copolymers being the best performing in the set. The composition ratios from 50:50 to 60:40 of the AF6/PEGMA side groups were shown to be more effective, with several films exhibiting spontaneous removal of the sporelings. The cells of N. incerta were also removed from several coating compositions. All films were characterized by surface techniques including captive bubble contact angle, atomic force microscopy, and near edge X-ray absorption fine structure spectroscopy to correlate surface chemistry and morphology with biological performance.« less

Effects of the PPy layer thickness on Co-PPy composite films

NASA Astrophysics Data System (ADS)

Haciismailoglu, Murside

2015-11-01

Co-PPy composite films were electrodeposited on ITO substrate from two different solutions potentiostatically. Firstly, the PPy layers with the thicknesses changing from 20 to 5000 nm were produced on ITO. Then Co was electrodeposited on these PPy/ITO substrates with a charge density of 1000 mC cm-2. The electrochemical properties were investigated by the current density-time transients and the variation of the elapsed time for the Co deposition depending on the PPy layer thickness. X-ray photoelectron (XPS) spectra indicated the presence of both Co metal and its oxides on the surface. The weak reflections of the Co3O4, CoO and hcp Co were detected by the X-ray diffraction (XRD) technique. According to scanning electron microscopy (SEM) images, the thickness of the PPy layer strongly affects the Co nucleation. The composite films with the PPy layer thinner than 200 nm and thicker than 2000 nm have an isotropic magnetic behavior due to the symmetrical crystal field. The composite films with the PPy layer thicknesses between 200 and 2000 nm have an anisotropic magnetic behavior attributable to the deterioration of this symmetrical crystal field by the PPy bubbles on the surface. All films are hard magnetic material, since the coercivities are larger than 125 Oe.

Composition gradient optimization and electrical characterization of (Pb, Ca)TiO3 thin films

NASA Astrophysics Data System (ADS)

Bao, Dinghua; Mizutani, Nobuyasu; Zhang, Liangying; Yao, Xi

2001-01-01

Compositionally graded (Pb, Ca)TiO3 thin films were prepared by a monoethanolamine-modified sol-gel technique on platinum-coated silicon substrates at the annealing temperature of 600 °C. The composition gradient of the films was greatly improved by a modified annealing method. The dielectric constants, for up-graded and down-graded films annealed at 600 °C for 60 min, were found to be 469 and 355, respectively. Both were larger than those reported for conventional (Pb, Ca)TiO3 thin films. The compositionally graded films had large polarization offsets in hysteresis loops when excited by an alternating electric field. The more smooth the composition gradient of the graded film, the larger the polarization offset. This was consistent with a theoretical model reported previously by Mantese and coworkers [Appl. Phys. Lett. 71, 2047 (1997)]. The magnitude of polarization offset displayed a power-law dependence on the electric field, and the direction of the offset depended on the direction of the composition gradient with respect to the substrate. Both up-graded and down-graded films had good leakage current characteristics.

Effects of rf power on chemical composition and surface roughness of glow discharge polymer films

NASA Astrophysics Data System (ADS)

Zhang, Ling; He, Xiaoshan; Chen, Guo; Wang, Tao; Tang, Yongjian; He, Zhibing

2016-03-01

The glow discharge polymer (GDP) films for laser fusion targets were successfully fabricated by plasma enhanced chemical vapor deposition (PECVD) at different radio frequency (rf) powers. The films were deposited using trans-2-butene (T2B) mixed with hydrogen as gas sources. The composition and state of plasma were diagnosed by quadrupole mass spectrometer (QMS) and Langmuir probe during the deposition process. The composition, surface morphology and roughness were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and white-light interferometer (WLI), respectively. Based on these observation and analyses, the growth mechanism of defects in GDP films were studied. The results show that, at low rf power, there is a larger probability for secondary polymerization and formation of multi-carbon C-H species in the plasma. In this case, the surface of GDP film turns to be cauliflower-like. With the increase of rf power, the degree of ionization is high, the relative concentration of smaller-mass hydrocarbon species increases, while the relative concentration of larger-mass hydrocarbon species decreases. At higher rf power, the energy of smaller-mass species are high and the etching effects are strong correspondingly. The GDP film's surface roughness shows a trend of decrease firstly and then increase with the increasing rf power. At rf power of 30 W, the surface root-mean-square roughness (Rq) drops to the lowest value of 12.8 nm, and no ;void; defect was observed.

{112} Polar surfaces of copper(indium,gallium)selenide: Properties and effects on crystal growth

NASA Astrophysics Data System (ADS)

Liao, Dongxiang

Cu(In,Ga)Se2 (GIGS) are promising materials for thin film photovoltaic applications. This work studies the epitaxial growth of CIGS single crystal films on GaAs substrates of various orientations and characterizes the properties of the thin films. A surprising finding is the strong tendency of film surfaces to facet to {112} planes. The work attempted to establish the connections between the film morphology, the surface energies, the surface chemical compositions, and the reconstruction of polar surfaces. Using angle-resolved photoelectron emission spectroscopy, I found that there is a severe Cu depletion at the first 1-2 layer of the free surface of CuInSe2 and the surface is semiconducting. The results strongly support the model of a reconstructed non-stoichiometric polar surface and exclude the previously believed existence of a bulk second phase on the CIS surface. Unique features of the film morphology suggest that the properties and structure of the polar surfaces have great effects on the growth of the crystals, and probably on the incorporation of the large amount of point defects. Measured chemical composition profiles indicate that the Cu depletion observed on free CIGS surface remains at the CIGS/CdS heterojunction interface and Cd is incorporated into the surface of CIGS. It is proposed that this non-stoichiometric composition leads to charge imbalance at the interface and causes the type-inversion of the CIGS surface, which are favorable for the device performance.

Sequentially evaporated thin Y-Ba-Cu-O superconductor films: Composition and processing effects

NASA Technical Reports Server (NTRS)

Valco, George J.; Rohrer, Norman J.; Warner, Joseph D.; Bhasin, Kul B.

1988-01-01

Thin films of YBa2Cu3O(7-beta) have been grown by sequential evaporation of Cu, Y, and BaF2 on SrTiO3 and MgO substrates. The onset temperatures were as high as 93 K while T sub c was 85 K. The Ba/Y ratio was varied from 1.9 to 4.0. The Cu/Y ratio was varied from 2.8 to 3.4. The films were then annealed at various times and temperatures. The times ranged from 15 min to 3 hr, while the annealing temperatures used ranged from 850 C to 900 C. A good correlation was found between transition temperature (T sub c) and the annealing conditions; the films annealed at 900 C on SrTiO3 had the best T sub c's. There was a weaker correlation between composition and T sub c. Barium poor films exhibitied semiconducting normal state resistance behavior while barium rich films were metallic. The films were analyzed by resistance versus temperature measurements and scanning electron microscopy. The analysis of the films and the correlations are reported.

The luminescent properties of polyethylene films with admixtures of luminophores based on europium compounds

NASA Astrophysics Data System (ADS)

Kalinovskaya, I. V.; Zadorozhnaya, A. N.; Karasev, V. E.

2008-11-01

Polyethylene films activated with europium(III) complexes with carboxylic acids and Eu(L)3 · nD · xH2O + ANT compositions, where L is the trifluoroacetic, toluyl, or cinnamic acid anion and ANT is anthranilic acid, were prepared. The intensity of luminescence of the polymeric compositions depended on the content of luminophores (molar ratio between europium compounds and anthranilic acid). An analysis of the excitation spectra showed that, in polymer—Eu(L)3 · nPhen · xH2O + ANT compositions, there was effective energy transfer from phenanthroline to anthranilic acid levels.

Amorphous Mixed-Metal Oxide Thin Films from Aqueous Solution Precursors with Near-Atomic Smoothness.

PubMed

Kast, Matthew G; Cochran, Elizabeth A; Enman, Lisa J; Mitchson, Gavin; Ditto, Jeffrey; Siefe, Chris; Plassmeyer, Paul N; Greenaway, Ann L; Johnson, David C; Page, Catherine J; Boettcher, Shannon W

2016-12-28

Thin films with tunable and homogeneous composition are required for many applications. We report the synthesis and characterization of a new class of compositionally homogeneous thin films that are amorphous solid solutions of Al 2 O 3 and transition metal oxides (TMO x ) including VO x , CrO x , MnO x , Fe 2 O 3 , CoO x , NiO, CuO x , and ZnO. The synthesis is enabled by the rapid decomposition of molecular transition-metal nitrates TM(NO 3 ) x at low temperature along with precondensed oligomeric Al(OH) x (NO 3 ) 3-x cluster species, both of which can be processed from aq solution. The films are dense, ultrasmooth (R rms < 1 nm, near 0.1 nm in many cases), and atomically mixed amorphous metal-oxide alloys over a large composition range. We assess the chemical principles that favor the formation of amorphous homogeneous films over rougher phase-segregated nanocrystalline films. The synthesis is easily extended to other compositions of transition and main-group metal oxides. To demonstrate versatility, we synthesized amorphous V 0.1 Cr 0.1 Mn 0.1 Fe 0.1 Zn 0.1 Al 0.5 O x and V 0.2 Cr 0.2 Fe 0.2 Al 0.4 O x with R rms ≈ 0.1 nm and uniform composition. The combination of ideal physical properties (dense, smooth, uniform) and broad composition tunability provides a platform for film synthesis that can be used to study fundamental phenomena when the effects of transition metal cation identity, solid-state concentration of d-electrons or d-states, and/or crystallinity need to be controlled. The new platform has broad potential use in controlling interfacial phenomena such as electron transfer in solar-cell contacts or surface reactivity in heterogeneous catalysis.

[Spectroscopic study on film formation mechanism and structure of composite silanes-V-Zr passive film].

PubMed

Wang, Lei; Liu, Chang-sheng; Shi, Lei; An, Cheng-qiang

2015-02-01

A composite silanes-V-Zr passive film was overlayed on hot-dip galvanized steel. Attenuated total reflection Fourier transformed infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectrometer (XPS) and radio frequency glow discharge optical emission spectrometry (rf-GD-OES) were used to characterize the molecular structure of the silanes-V-Zr passive film. The mechanism of film formation was discussed: The results show that the silane molecules are crosslinked as the main film former and inorganic inhibitor is even distributed in the film. The fitting peak of 100.7 eV in XPS single Si2p energy range spectra of the composite silanes-V-Zr passive film and the widening and strengthening of the Si--O infrared absorption peak at 1100 cm(-1) indicate that the silanes were adsorbed on the surface of zinc with chemical bond of Si--O--Zn, and the silane molecules were connected with each other by bond of Si--O--Si. Two characteristic absorption peaks of amide at 1650 and 1560 cm(-1) appear in the infrared spectroscopy of the composite silanes-V-Zr passive film, and a characteristic absorption peak of epoxy groups at 910 cm(-1) disappears in the infrared spectroscopy of the passive film. The results indicate that gamma-APT can be prepared through nucleophilic ring-opening of ethylene oxide in gamma-GPT molecule to form C--N covalent bonds. The rf-GD-OES results indicate that there is a oxygen enriched layer in 0.3 microm depth of the composite silanes-V-Zr passive film. Moreover, ZrF4, ZrO2 and some inorganic matter obtained by the reaction during the forming processof the composite silanes-V-Zr passive film are distributed evenly throughout the film. According to the film composition, the physical processes and chemical reactions during the film forming process were studied by using ATR-FTIR. Based on this, the film forming mechanism was proposed.

Effects of Graphene Oxide Addition on Mechanical and Thermal Properties of Evoh Films

NASA Astrophysics Data System (ADS)

González-Ruiz, Jesús; Yataco-Lazaro, Lourde; Virginio, Sueli; das Graças da Silva-Valenzuela, Maria; Moura, Esperidiana; Valenzuela-Díaz, Francisco

Currently, ethylene vinyl alcohol (EVOH) is one of the oxygen barrier materials most used for food packaging. The addition of graphene oxide nanosheets to the EVOH matrix is employed to improve their mechanic al and barrier properties. In this work, films of EVOH-based composites reinforced with graphene oxide were prepared by melt extrusion, using a twin screw extruder machine and blown extrusion process. The graphene oxide was prepared via chemical oxidation of natural graphite and then was exfoliated into nanosheets using the sonochemical method. The composite films samples were characterized using FTIR and DSC analysis. In addition, their mechanical properties were also determined.

Flexible Transparent Conductive Films with High Performance and Reliability Using Hybrid Structures of Continuous Metal Nanofiber Networks for Flexible Optoelectronics.

PubMed

Park, Juyoung; Hyun, Byung Gwan; An, Byeong Wan; Im, Hyeon-Gyun; Park, Young-Geun; Jang, Junho; Park, Jang-Ung; Bae, Byeong-Soo

2017-06-21

We report an Ag nanofiber-embedded glass-fabric reinforced hybrimer (AgNF-GFRHybrimer) composite film as a reliable and high-performance flexible transparent conducting film. The continuous AgNF network provides superior optoelectronic properties of the composite film by minimizing transmission loss and junction resistance. In addition, the excellent thermal/chemical stability and mechanical durability of the GFRHybrimer matrix provides enhanced mechanical durability and reliability of the final AgNF-GFRHybrimer composite film. To demonstrate the availability of our AgNF-GFRHybrimer composite as a transparent conducting film, we fabricated a flexible organic light-emitting diode (OLED) device on the AgNF-GFRHybrimer film; the OLED showed stable operation during a flexing.

Using sub-micron silver-nanoparticle based films to counter biofilm formation by Gram-negative bacteria

NASA Astrophysics Data System (ADS)

Gillett, A. R.; Baxter, S. N.; Hodgson, S. D.; Smith, G. C.; Thomas, P. J.

2018-06-01

Composite films comprised of silver nanoparticles (AgNPs) grown using a low-cost straightforward chemical bath based method have been deposited on glass microscope slides to investigate their potential as a sacrificial antibacterial coating. The as-deposited films have been characterised using scanning electron microscopy (SEM) and optical profilometry. These suggested that the films were relatively uniform in coverage. Chemical composition of the AgNP films has been studied by using X-ray photoelectron spectroscopy (XPS). The XPS analysis indicated that the Ag was in a metallic form able to sustain plasmon behaviour, and that low levels of residual nanoparticle precursors were present. Particle size was characterised using transmission electron microscopy (TEM) which showed an average particle size of 10.6 nm. The effectiveness of the films as an antibacterial coating was tested against Escherichia coli. The AgNP film was determined to be effective in the killing of E. coli cells over a 24 h period when compared to equivalent samples that contained no silver. Of particular note was that only minimal bacterial growth was detected over the first 12 h of testing, up to 78.6 times less than the control samples, suggesting the film is very efficient at slowing initial biofilm formation. The use of AgNP based films that have been synthesised using a novel low-cost, low-temperature and highly upscalable method is demonstrated as a promising solution for the deployment of silver as an effective sacrifical antimicrobial coating to counter the formation of potentially hazardous Gram negative biofilms.

Influence of external magnetic field on the microwave absorption properties of carbonyl iron and polychloroprene composites film

NASA Astrophysics Data System (ADS)

Wang, Haiyan; Li, Mingjie; Li, Xueai

2016-12-01

The carbonyl iron particles were dispersed in a polychloroprene rubber (CR) matrix under a magnetic field for a practical application as microwave absorption composites film. In comparison with the carbonyl iron particles (CIP)/CR composites film prepared by general route, such films made with external magnetic field exhibit excellent microwave absorption properties, strongly depending on the increment of anisotropy and rearrangement of magnetic particles. The film made under external magnetic field with a thickness of only 0.54 mm shows least reflection loss of -15.98 dB and the reflection loss value less than -10.0 dB over the frequency range of 11.4˜14.8 GHz. The results indicated the composite film made under external magnetic field have excellent microwave absorption properties, which suggest that the composites thin film could be used as a thinner and lighter microwave absorber.

Epitaxial growth and physical properties of ternary nitride thin films by polymer-assisted deposition

NASA Astrophysics Data System (ADS)

Enriquez, Erik; Zhang, Yingying; Chen, Aiping; Bi, Zhenxing; Wang, Yongqiang; Fu, Engang; Harrell, Zachary; Lü, Xujie; Dowden, Paul; Wang, Haiyan; Chen, Chonglin; Jia, Quanxi

2016-08-01

Epitaxial layered ternary metal-nitride FeMoN2, (Fe0.33Mo0.67)MoN2, CoMoN2, and FeWN2 thin films have been grown on c-plane sapphire substrates by polymer-assisted deposition. The ABN2 layer sits on top of the oxygen sublattices of the substrate with three possible matching configurations due to the significantly reduced lattice mismatch. The doping composition and elements affect not only the out-of-plane lattice parameters but also the temperature-dependent electrical properties. These films have resistivity in the range of 0.1-1 mΩ.cm, showing tunable metallic or semiconducting behaviors by adjusting the composition. A modified parallel connection channel model has been used to analyze the grain boundary and Coulomb blockade effect on the electrical properties. The growth of the high crystallinity layered epitaxial thin films provides an avenue to study the composition-structure-property relationship in ABN2 materials through A and B-site substitution.

Supercapacitors based on flexible graphene/polyaniline nanofiber composite films.

PubMed

Wu, Qiong; Xu, Yuxi; Yao, Zhiyi; Liu, Anran; Shi, Gaoquan

2010-04-27

Composite films of chemically converted graphene (CCG) and polyaniline nanofibers (PANI-NFs) were prepared by vacuum filtration the mixed dispersions of both components. The composite film has a layered structure, and PANI-NFs are sandwiched between CCG layers. Furthermore, it is mechanically stable and has a high flexibility; thus, it can be bent into large angles or be shaped into various desired structures. The conductivity of the composite film containing 44% CCG (5.5 x 10(2) S m(-1)) is about 10 times that of a PANI-NF film. Supercapacitor devices based on this conductive flexible composite film showed large electrochemical capacitance (210 F g(-1)) at a discharge rate of 0.3 A g(-1). They also exhibited greatly improved electrochemical stability and rate performances.

Polyethylene-Carbon Nanotube Composite Film Deposited by Cold Spray Technique

NASA Astrophysics Data System (ADS)

Ata, Nobuhisa; Ohtake, Naoto; Akasaka, Hiroki

2017-10-01

Carbon nanotubes (CNTs) are high-performance materials because of their superior electrical conductivity, thermal conductivity, and self-lubrication, and they have been studied for application to polymer composite materials as fillers. However, the methods of fabricating polymer composites with CNTs, such as injection molding, are too complicated for industrial applications. We propose a simple cold spray (CS) technique to obtain a polymer composite of polyethylene (PE) and CNTs. The composite films were deposited by CS on polypropylene and nano-porous structured aluminum substrates. The maximum thickness of the composite film was approximately 1 mm. Peaks at G and D bands were observed in the Raman spectra of the films. Scanning electron microscopy images of the film surface revealed that PE particles were melted by the acceleration gas and CNTs were attached with melted PE. The PE particles solidified after contact with the substrate. These results indicate that PE-CNT composite films were successfully deposited on polypropylene and nano-porous structured aluminum substrates by CS.

Effect of the Ti/Si ratio of spin coating solutions on surface passivation of crystalline silicon by TiO x -SiO x composite films

NASA Astrophysics Data System (ADS)

Yoshiba, Shuhei; Tanitsu, Katsuya; Suda, Yoshiyuki; Kamisako, Koichi

2017-06-01

Passivation films or antireflection coatings are generally prepared using costly vacuum or high-temperature processes. Thus, we report the preparation of TiO x -SiO x composite films by novel spin coatable solutions for the synthesis of low-cost passivation coating materials. The desired films were formed by varying the mixing ratios of TiO x and SiO x , and the resulting films exhibited excellent surface passivation properties. For the p-type wafer, an optimal effective surface recombination velocity (S eff) of 93 cm/s was achieved at \\text{TiO}x:\\text{SiO}x = 6:4, while a surface recombination current density (J 0s) of 195 fA/cm2 was obtained. In contrast, for the n-type wafer, an S eff of 27 cm/s and a J 0s of 38 fA/cm2 were achieved at \\text{TiO}x:\\text{SiO}x = 8:2. This excellent surface passivation effect could be attributed to the low interface state density and high positive fixed charge density. Furthermore, the thickness of the interfacial SiO x layer was determined to be important for obtaining the desired surface passivation effect.

Influence of sulfurization temperature on Cu2ZnSnS4 absorber layer on flexible titanium substrates for thin film solar cells

NASA Astrophysics Data System (ADS)

Gokcen Buldu, Dilara; Cantas, Ayten; Turkoglu, Fulya; Gulsah Akca, Fatime; Meric, Ece; Ozdemir, Mehtap; Tarhan, Enver; Ozyuzer, Lutfi; Aygun, Gulnur

2018-02-01

In this study, the effect of sulfurization temperature on the morphology, composition and structure of Cu2ZnSnS4 (CZTS) thin films grown on titanium (Ti) substrates has been investigated. Since Ti foils are flexible, they were preferred as a substrate. As a result of their flexibility, they allow large area manufacturing and roll-to-roll processes. To understand the effects of sulfurization temperature on the CZTS formation on Ti foils, CZTS films fabricated with various sulfurization temperatures were investigated with several analyses including x-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy and Raman scattering. XRD measurements showed a sharp and intense peak coming from the (112) planes of the kesterite type lattice structure (KS), which is strong evidence for good crystallinity. The surface morphologies of our thin films were investigated using SEM. Electron dispersive spectroscopy was also used for the compositional analysis of the thin films. According to these analysis, it is observed that Ti foils were suitable as substrates for the growth of CZTS thin films with desired properties and the sulfurization temperature plays a crucial role for producing good quality CZTS thin films on Ti foil substrates.

Effect of cassava peel and cassava bagasse natural fillers on mechanical properties of thermoplastic cassava starch: Comparative study

NASA Astrophysics Data System (ADS)

Edhirej, Ahmed; Sapuan, S. M.; Jawaid, Mohammad; Zahari, Nur Ismarrubie; Sanyang, M. L.

2017-12-01

Increased awareness of environmental and sustainability issues has generated increased interest in the use of natural fiber reinforced composites. This work focused on the use of cassava roots peel and bagasse as natural fillers of thermoplastic cassava starch (TPS) materials based on cassava starch. The effect of cassava bagasse (CB) and cassava peel (CP) content on the tensile properties of cassava starch (CS) biocomposites films was studied. The biocomposites films were prepared by casting technique using cassava starch (CS) as matrix and fructose as plasticizer. The CB and CP were added to improve the properties of the films. The addition of both fibers increased the tensile strength and modulus while decreased the elongation at break of the biocomposites films. Films containing CB showed higher tensile strength and modulus as compared to the films containing the same amount of CP. The addition of 6 % bagasse increased the modulus and maximum tensile stress to 581.68 and 10.78 MPa, respectively. Thus, CB is considered to be the most efficient reinforcing agent due to its high compatibility with the cassava starch. The use of CB and CP as reinforcement agents for CS thermoplastic cassava added value to these waste by-products and increase the suitability of CS composite films as environmentally friendly food packaging material.

Processing effects on microstructure, percolation and resistive sensor properties of nickel-zirconium oxide cermet films on silicon substrates

NASA Astrophysics Data System (ADS)

Sundeen, John Edward, Jr.

Thin Ni-ZrO2 cermet films were developed on silicon substrates using solution based, metallo-organic deposition (MOD) technique. The nickel based cermet films on silicon are of interest for heater, temperature and flow sensor devices, particularly in automotive or aerospace applications at UP to 250°C. In this study, precursors for the NiO-ZrO2 composite films were derived from metal carboxylate and nitrate based solutions. Composition and heat treatment conditions were the main process variables for controlling the structure, particle size and morphology, on which the electrical properties depend. Electrical resistance behavior was studied for Ni-ZrO2 films with 25--78 vol.% Ni content. This Ni amount exceeds the percolation threshold for conduction. The dependence of the resistance on individual processing variables, including film thickness, ambient flow rate, sintering temperature and time, and specimen geometry was studied. Electrical characterization included establishing the percolative resistive behavior in the MOD Ni-ZrO2 films. A resistive percolation threshold (pc) at ˜25 vol.% Ni was found for 800°C sintered, 1mum thick Ni-ZrO2 films. Existing models including the general effective media (GEM) percolation equation, and mixture rules were used to develop a predictive expression for Ni-ZrO2 film resistance as a function of composition. Kinetic analysis of particle size in the 55 vol.% Ni cermet films was directly correlated to the sheet resistance (Rs) of the films. The temperature coefficient of resistance (TCR) was also correlated to R s, by the equation: (TCR)alpha = alphao - betaR s. These electrical characteristics make the films suitable for use as gas flow and temperature sensors. Calculated figure of merit (rho-TCR), values for the MOD Ni-ZrO2 films Compared favorably to commercial Pt and Ni based thin and thick film formulations used for heaters and thermal sensors. An added advantage of the MOD Ni-ZrO2, compared to the non-linear behavior of Ni, was that film resistance response to temperature is highly linear over the temperature range of 20--160°C. Select films could be heated to 45--100°C with a low (I2R) power input of 400mW-2W. Then films demonstrated stable hot resistance, high sensitivity and rapid response to gas flow. Significant accomplishments from this work included the development of: (a) MOD derived cermet films of 40--78 vol.% Ni, with high positive TCR of 2600--4250ppm/°C and Rs of 2.5--60%O/□/1mum which are highly suitable for thermal sensing applications, (b) A simple mixture rule rho = rhoo - m·VNi describing the film resistivity with composition; and (c) Expressions correlating film TCR and resistance to sintering time and temperature using particle growth kinetics.

Photocatalytic Antibacterial Performance of Glass Fibers Thin Film Coated with N-Doped SnO 2 /TiO 2

PubMed Central

Sikong, Lek; Niyomwas, Sutham; Rachpech, Vishnu

2014-01-01

Both N-doped and undoped thin films of 3SnO2/TiO2 composite were prepared, by sol-gel and dip-coating methods, and then calcined at 600°C for 2 hours. The films were characterized by FTIR, XRD, UV-Vis, SEM, and XPS, and their photocatalytic activities to degrade methylene blue in solution were determined, expecting these activities to correlate with the inactivation of bacteria, which was confirmed. The doped and undoped films were tested for activities against Gram-negative Escherichia coli (E. coli) and Salmonella typhi (S. typhi), and Gram-positive Staphylococcus aureus (S. aureus). The effects of doping on these composite films included reduced energy band gap, high crystallinity of anatase phase, and small crystallite size as well as increased photocatalytic activity and water disinfection efficiency. PMID:24693250

The Effects of Film Thickness and Evaporation Rate on Si-Cu Thin Films for Lithium Ion Batteries.

PubMed

Polat, B Deniz; Keles, Ozgul

2015-12-01

The reversible cyclability of Si based composite anodes is greatly improved by optimizing the atomic ratio of Si/Cu, the thickness and the evaporation rates of films fabricated by electron beam deposition method. The galvanostatic test results show that 500 nm thick flim, having 10%at. Cu-90%at. Si, deposited with a moderate evaporation rate (10 and 0.9 Å/s for Si and Cu respectively) delivers 2642.37 mAh g(-1) as the first discharge capacity with 76% Coulombic efficiency. 99% of its initial capacity is retained after 20 cycles. The electron conductive pathway and high mechanical tolerance induced by Cu atoms, the low electrical resistivity of the film due to Cu3Si particles, and the homogeneously distributed nano-sized/amorphous particles in the composite thin film could explain this outstanding electrochemical performance of the anode.

Transglutaminase-induced crosslinking of gelatin-calcium carbonate composite films.

PubMed

Wang, Yuemeng; Liu, Anjun; Ye, Ran; Wang, Wenhang; Li, Xin

2015-01-01

The effects of transglutaminase (TGase) on the rheological profiles and interactions of gelatin-calcium carbonate solutions were studied. In addition, mechanical properties, water vapour permeability and microstructures of gelatin-calcium carbonate films were also investigated and compared. Fluorescence data suggested that the interaction of TGase and gelation-calcium carbonate belonged to a static quenching mechanism, and merely one binding site between TGase and gelatin-calcium carbonate was identified. Moreover, differential scanning calorimetry (DSC), the mechanical properties and the water vapour permeability studies revealed that TGase favoured the strong intramolecular polymerisation of the peptides in gelatin. The microstructures of the surfaces and cross sections in gelatin-calcium carbonate films were shown by scanning electron microscope (SEM) micrographs. The results of the fourier transform infrared spectroscopy (FTIR) indicated that TGase caused conformational changes in the proteins films. Therefore, TGase successfully facilitated the formation of gelatin-calcium carbonate composite films. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ceramic Composite Thin Films

NASA Technical Reports Server (NTRS)

Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor); Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor)

2013-01-01

A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

Effect of Doping Materials on the Low-Level NO Gas Sensing Properties of ZnO Thin Films

NASA Astrophysics Data System (ADS)

Çorlu, Tugba; Karaduman, Irmak; Yildirim, Memet Ali; Ateş, Aytunç; Acar, Selim

2017-07-01

In this study, undoped, Cu-doped, and Ni-doped ZnO thin films have been successfully prepared by successive ionic layer adsorption and reaction method. The structural, compositional, and morphological properties of the thin films are characterized by x-ray diffractometer, energy dispersive x-ray analysis (EDX), and scanning electron microscopy, respectively. Doping effects on the NO gas sensing properties of these thin films were investigated depending on gas concentration and operating temperature. Cu-doped ZnO thin film exhibited a higher gas response than undoped and Ni-doped ZnO thin film at the operating temperature range. The sensor with Cu-doped ZnO thin film gave faster responses and recovery speeds than other sensors, so that is significant for the convenient application of gas sensor. The response and recovery speeds could be associated with the effective electron transfer between the Cu-doped ZnO and the NO molecules.

Composition dependence of structural and optical properties in epitaxial Sr(Sn1-xTix)O3 films

NASA Astrophysics Data System (ADS)

Liu, Qinzhuang; Li, Bing; Li, Hong; Dai, Kai; Zhu, Guangping; Wang, Wei; Zhang, Yongxing; Gao, Guanyin; Dai, Jianming

2015-03-01

Epitaxial Sr(Sn1-xTix)O3 (SSTO, x = 0-1) thin films were grown on MgO substrates by a pulsed laser deposition technique. The effects of composition on the structural and optical properties of SSTO films were investigated. X-ray diffraction studies show that the lattice parameter decreases from 4.041 to 3.919 Å gradually with increasing Ti content from 0 to 1 in SSTO films. Optical spectra analysis reveals that the band gap energy Eg decreases continuously from 4.44 to 3.78 eV over the entire doping range, which is explained by the decreasing degree of octahedral tilting distortion and thus the increasing tolerance factor caused by the increasing small-Ti-ion doping concentration.

Electron mobility enhancement in epitaxial multilayer Si-Si/1-x/Ge/x/ alloy films on /100/Si

NASA Technical Reports Server (NTRS)

Manasevit, H. M.; Gergis, I. S.; Jones, A. B.

1982-01-01

Enhanced Hall-effect mobilities have been measured in epitaxial (100)-oriented multilayer n-type Si/Si(1-x)Ge(x) films grown on single-crystal Si substrates by chemical vapor deposition. Mobilities from 20 to 40% higher than that of epitaxial Si layers and about 100% higher than that of epitaxial SiGe layers on Si were measured for the doping range 8 x 10 to the 15th to 10 to the 17th/cu cm. No mobility enhancement was observed in multilayer p-type (100) films and n-type (111)-oriented films. Experimental studies included the effects upon film properties of layer composition, total film thickness, doping concentrations, layer thickness, and growth temperature.

Longitudinal spin Seebeck effect in Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} prepared on gadolinium gallium garnet (001) by metal organic decomposition method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asada, H., E-mail: asada@yamaguchi-u.ac.jp; Kuwahara, A.; Sakata, N.

2015-05-07

Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} thin films with the Ga composition x = 0, 0.5, and 1.0 are prepared on (001) oriented gadolinium gallium garnet substrates by a metal organic decomposition method. Only (001) peaks are observed in x-ray diffraction patterns for all the films, suggesting that the highly oriented Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} thin films were formed. Increasing Ga composition, the saturation magnetization decreases, and the perpendicular easy axis is enhanced due to the decrease of the shape anisotropy. Longitudinal spin Seebeck effects (LSSEs) in Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} thin films with a Pt layer of 10 nm in thicknessmore » were investigated. Magnetic field dependence of the thermoelectric voltage caused by the LSSE in Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} films indicates the hysteresis loop with the small coercivity reflecting the magnetization curve. The decrease of LSSE voltage in Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} is clearly observed with the decrease of Fe composition.« less

3-dimensional free standing micro-structures by proton beam writing of Su 8-silver nanoParticle polymeric composite

NASA Astrophysics Data System (ADS)

Igbenehi, H.; Jiguet, S.

2012-09-01

Proton beam lithography a maskless direct-write lithographic technique (well suited for producing 3-Dimensional microstructures in a range of resist and semiconductor materials) is demonstrated as an effective tool in the creation of electrically conductive freestanding micro-structures in an Su 8 + Nano Silver polymer composite. The structures produced show non-ohmic conductivity and fit the percolation theory conduction model of tunneling of separated nanoparticles. Measurements show threshold switching and a change in conductivity of at least 4 orders of magnitude. The predictable range of protons in materials at a given energy is exploited in the creation of high aspect ratio, free standing micro-structures, made from a commercially available SU8 Silver nano-composite (GMC3060 form Gersteltec Inc. a negative tone photo-epoxy with added metallic nano-particles(Silver)) to create films with enhanced electrical properties when exposed and cured. Nano-composite films are directly written on with a finely focused MeV accelerated Proton particle beam. The energy loss of the incident proton beams in the target polymer nano- composite film is concentrated at the end of its range, where damage occurs; changing the chemistry of the nano-composite film via an acid initiated polymerization - creating conduction paths. Changing the energy of the incident beams provide exposed regions with different penetration and damage depth - exploited in the demonstrated cantilever microstructure.

Toward compositional design of reticular type porous films by mixing and coating titania-based frameworks with silica

NASA Astrophysics Data System (ADS)

Kimura, T.

2015-12-01

A recently developed reticular type porous structure, which can be fabricated as the film through the soft colloidal block copolymer (e.g., PS-b-PEO) templating, is very promising as the porous platform showing high-performance based on its high surface area as well as high diffusivity of targeted organic molecules and effective accommodation of bulky molecules, but the compositional design of oxide frameworks has not been developed so enough to date. Here, I report reliable synthetic methods of the reticular type porous structure toward simple compositional variations. Due to the reproducibility of reticular type porous titania films from titanium alkoxide (e.g., TTIP; titanium tetraisopropoxide), a titania-silica film having similar porous structure was obtained by mixing silicon alkoxide (e.g., tetraethoxysilane) and TTIP followed by their pre-hydrolysis, and the mixing ratio of Ti to Si composition was easily reached to 1.0. For further compositional design, a concept of surface coating was widely applicable; the reticular type porous titania surfaces can be coated with other oxides such as silica. Here, a silica coating was successfully achieved by the simple chemical vapor deposition of silicon alkoxide (e.g., tetramethoxysilane) without water (with water at the humidity level), which was also utilized for pore filling with silica by the similar process with water.

Effects of Partial Replacement of Eggshell Powder by Halloysite Nanotubes on the Properties of Polyvinyl Alcohol Composites

NASA Astrophysics Data System (ADS)

Alias, N. F.; Ismail, H.

2018-06-01

Polyvinyl alcohol (PVA)/eggshell powder (ESP) were prepared via solution casting method. The effects of gradual replacement of ESP by halloysite nanotubes (HNTs) were investigated based on tensile properties, physical properties and biodegradability. The main objective is to study the effect of hybrid fillers and also to compare the properties of PVA/ESP composite with conventional filler, HNT. The tensile properties decreased with increasing HNT loading. Scanning electron microscopy (SEM) studies showed that agglomeration of filler were present throughout the composites. Due to the presence of hydroxyl group on the outer and inner surface of HNT, the water absorption and water vapor transmisibility were found to increase with increasing HNTs loading. The biodegradability of film filled with HNT is lower compared to the film filled with ESP.

Poly(malachite green) at nafion doped multi-walled carbon nanotube composite film for simple aliphatic alcohols sensor.

PubMed

Umasankar, Yogeswaran; Periasamy, Arun Prakash; Chen, Shen-Ming

2010-01-15

Conductive composite film which contains nafion (NF) doped multi-walled carbon nanotubes (MWCNTs) along with the incorporation of poly(malachite green) (PMG) has been synthesized on glassy carbon electrode (GCE), gold and indium tin oxide (ITO) electrodes by potentiostatic methods. The presence of MWCNTs in the composite film (MWCNTs-NF-PMG) enhances surface coverage concentration (Gamma) of PMG to approximately 396%, and increases the electron transfer rate constant (k(s)) to approximately 305%. Similarly, electrochemical quartz crystal microbalance study reveals the enhancement in the deposition of PMG at MWCNTs-NF film. The surface morphology of the composite film deposited on ITO electrode has been studied using scanning electron microscopy (SEM) and scanning tunneling microscopy (STM). These two techniques reveal that the PMG incorporated on MWCNTs-NF film. The MWCNTs-NF-PMG composite film also exhibits promising enhanced electrocatalytic activity towards the simple aliphatic alcohols such as methanol, ethanol and propanol. The electroanalytical responses of analytes at NF-PMG and MWCNTs-NF-PMG films were measured using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). From electroanalytical studies, well defined voltammetric peaks have been obtained at MWCNTs-NF-PMG composite film for methanol, ethanol and propanol at Epa=609, 614 and 602mV respectively. The sensitivity of MWCNTs-NF-PMG composite film towards methanol, ethanol and propanol in CV technique are 0.59, 0.36 and 0.92microAmM(-1)cm(-2) respectively, which are higher than NF-PMG film. Further, the sensitivity values obtained using DPV are higher than the values obtained using CV technique.

Liquid crystalline composites containing phyllosilicates

DOEpatents

Chaiko,; David, J [Naperville, IL

2007-05-08

The present invention provides barrier films having reduced gas permeability for use in packaging and coating applications. The barrier films comprise an anisotropic liquid crystalline composite layer formed from phyllosilicate-polymer compositions. Phyllosilicate-polymer liquid crystalline compositions of the present invention can contain a high percentage of phyllosilicate while remaining transparent. Because of the ordering of the particles in the liquid crystalline composite, barrier films comprising liquid crystalline composites are particularly useful as barriers to gas transport.

Space environmental effects on polymeric materials

NASA Technical Reports Server (NTRS)

Kiefer, Richard L.; Orwoll, Robert A.

1987-01-01

A study is presented of the effect of radiation on polymers. It helps to estimate the impact of the space environment on composite structures. Two commercially available polymer films were used; a polyetherimide, and a polysulfone. Both films were irradiated in vacuum with 85 KeV electron. Properties of the films before and after irradiation were monitored by tensile elongation measurements, ultraviolet/visible spectroscopy, glass transition temperature measurements, gel permeation chromatography, and infrared spectroscopy. The results of these characterizations are presented and briefly discussed.

Optical, electrical and dielectric properties of TiO2-SiO2 films prepared by a cost effective sol-gel process.

PubMed

Vishwas, M; Rao, K Narasimha; Gowda, K V Arjuna; Chakradhar, R P S

2011-12-01

Titanium dioxide (TiO(2)) and silicon dioxide (SiO(2)) thin films and their mixed films were synthesized by the sol-gel spin coating method using titanium tetra isopropoxide (TTIP) and tetra ethyl ortho silicate (TEOS) as the precursor materials for TiO(2) and SiO(2) respectively. The pure and composite films of TiO(2) and SiO(2) were deposited on glass and silicon substrates. The optical properties were studied for different compositions of TiO(2) and SiO(2) sols and the refractive index and optical band gap energies were estimated. MOS capacitors were fabricated using TiO(2) films on p-silicon (100) substrates. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics were studied and the electrical resistivity and dielectric constant were estimated for the films annealed at 200°C for their possible use in optoelectronic applications. Copyright © 2011 Elsevier B.V. All rights reserved.

Synthesis of transparent BaTiO3 nanoparticle/polymer composite film using DC field

NASA Astrophysics Data System (ADS)

Kondo, Yusuke; Okumura, Yasuko; Oi, Chifumi; Sakamoto, Wataru; Yogo, Toshinobu

2008-10-01

Transparent BaTiO3 nanoparticle/polymer composite films were synthesized from titanium-organic film and barium ion in aqueous solution under direct current (DC) field. Titanium-organic precursor was synthesized from titanium isopropoxide, acetylacetone and methacrylate derivative. The UV treatment was effective to increase the anti-solubility of the titanium-organic film during DC processing. BaTiO3 nanoparticles were crystallized in the precursor films on stainless substrates without high temperature process, as low as 40°C. The crystallite size of BaTiO3 increased with increasing reaction temperature from 40 to 50 °C at 3.0 V/cm. BaTiO3 nanoparticles also grew in size with increasing reaction time from 15 min to 45 min at 3.0 V/cm and 50 °C. Transparent BaTiO3 nanoparticle/polymer films were synthesized on stainless substrates at 3.0 V/cm and 50°C for 45 min.

Characterization of TiCN coatings deposited by magnetron sputter-ion plating process: RBS and GDOS complementary analyses

NASA Astrophysics Data System (ADS)

Freire, F. L., Jr.; Senna, L. F.; Achete, C. A.; Hirsch, T.

1998-03-01

Hard TiCN films were deposited by dc-magnetron sputter-ion plating technique onto high-speed carbon steel S-6-5-2 (M 2). For selected deposition conditions, TiCN films were also deposited onto Si substrates. A Ti target was sputtered in ArCH 4N 2 atmosphere. The argon flux (12 sccm) was fixed and corresponds to 90% of the total flux, whereas the N 2 flux ranged from 3% to 9% of the total flux. The total pressure in the chamber during film deposition was 8-9 × 10 -2Pa. The substrate bias, Vb, was between 0 and -140V and the substrate temperature, Ts, was 350°C. Film composition and depth profile of the elements were obtained by Rutherford backscattering spectrometry (RBS) and glow discharge optical spectroscopy (GDOS). Some limitations of both techniques in analysing TiCN films were presented. The effect of methane poisoing of the Ti target and how it influences the film composition was discussed.

Characterization of magneto-optical media

NASA Technical Reports Server (NTRS)

Hajjar, Roger A.; Wu, Te-Ho; Mansuripur, M.

1991-01-01

Amorphous rare earth-transition metal (RE-TM) alloys and compositionally modulated TM/TM films were characterized in terms of their magnetic, magneto-optic, and galvanomagnetic properties. The loop tracer, vibrating sample magnetometer (VSM), and Rutherford Backscattering (RBS) facility were used to characterize and analyze the various properties of these magneto-optical storage media. Kerr effect, ellipticity, coercivity, and anisotropy at various temperatures, magnetoresistance, and resistivity are among the properties measured in Co/Pt films, Co/Pd films, and TbFeCo films.

Multilayer composites and manufacture of same

DOEpatents

Holesinger, Terry G.; Jia, Quanxi

2006-02-07

The present invention is directed towards a process of depositing multilayer thin films, disk-shaped targets for deposition of multilayer thin films by a pulsed laser or pulsed electron beam deposition process, where the disk-shaped targets include at least two segments with differing compositions, and a multilayer thin film structure having alternating layers of a first composition and a second composition, a pair of the alternating layers defining a bi-layer wherein the thin film structure includes at least 20 bi-layers per micron of thin film such that an individual bi-layer has a thickness of less than about 100 nanometers.

Influence of gold species (AuCl4(-) and AuCl2(-)) on self-assembly of PS-b-P2VP in solutions and morphology of composite thin films fabricated at the air/liquid interfaces.

PubMed

Zhao, Xingjuan; Wang, Qian; Zhang, Xiaokai; Lee, Yong-Ill; Liu, Hong-Guo

2016-01-21

Composite thin films doped with Au species were fabricated at an air/liquid interface via a series of steps, including the mass transfer of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) across the liquid/liquid interface between a DMF/CHCl3 solution and an aqueous solution containing either AuCl4(-) or AuCl2(-), self-assembly of PS-b-P2VP in a mixed DMF-water solution, and adsorption and further self-organization of the formed aggregates at the air/liquid interface. This is a new approach for fabricating composite polymer films and can be completed within a very short time. AuCl4(-) and AuCl2(-) ions were found to significantly influence the self-assembly behavior of the block copolymer and the morphologies of the composite films, leading to the formation of nanowire arrays and a foam structure at the air/liquid interface, respectively, which originated from rod-like micelles and microcapsules that had formed in the respective solutions. The effect of the metal complex was analyzed based on the packing parameters of the amphiphilic polymer molecules in different microenvironments and the interactions between the pyridine groups and the metal chloride anions. In addition, these composite thin films exhibited stable and durable performance as heterogeneous catalysts for the hydrogenation of nitroaromatics in aqueous solutions.

Structural and Optical Properties of Cd 1- x Se x Thin Films Deposited by Electron Beam Evaporation Technique

NASA Astrophysics Data System (ADS)

Tripathi, Ravishankar Nath; Verma, Aneet Kumar; Rahul, Vishwakarma, S. R.

2011-10-01

Cadmium selenide (CdSe) thin films deposited by means of electron beam evaporation technique under high vacuum ˜10 -5 torr on ultrasonically cleaned glass substrate. Using stating materials of various compositions of cadmium and selenium using formula Cd 1- x Se x where x is orbitory constant having value 0.20≤ x ≤0.40 here we take less value of x for the creation of anion vacancy in thin films. In present work the structural properties have been studies using XRD technique and found that starting materials and thin films both are polycrystalline in nature having hexagonal structure. Here we study the effect of composition ratio Cd/Se in starting material and its prepared thin films on its grain size and lattice parameter. From the analysis of X-Ray diffractogram found that lattice parameter and grain size both are decreases with increasing Cd/Se ratio in thin films as well as in starting material the preferred orientation in thin films along (100) plane. The surface morphology was studied using SEM characterization and found that films are smooth and homogeneous. The films have been analysed for optical band gap and absorbed a direct band gap.

Innovative Linear Low Density Polyethylene Nanocomposite Films Reinforced with Organophilic Layered Double Hydroxides: Fabrication, Morphology and Enhanced Multifunctional Properties.

PubMed

Xie, Jiazhuo; Wang, Haijun; Wang, Zhou; Zhao, Qinghua; Yang, Yuechao; Waterhouse, Geoffrey I N; Hao, Lei; Xiao, Zihao; Xu, Jing

2018-01-08

Herein, we reported the successful development of novel nanocomposite films based on linear low density polyethylene (LLDPE) with enhanced anti-drop, optical, mechanical, thermal and water vapor barrier properties by introducing organophilic layered double hydroxides (OLDHs) nanosheets. OLDHs loadings were varied from 0-6 wt.%. Structural analyses using the Fourier transform infrared spectrum (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) indicated that the OLDHs nanosheets were homogeneously dispersed with an ordered alignment in the LLDPE matrix. The LLDPE film containing 2 wt.% OLDHs (denoted as OLDHs-2) showed the optimal mechanical, thermal and water vapor barrier properties, whilst the anti-drop and optical performance of the films improved with increasing OLDHs content. The enhanced antidrop properties of the composite films relative to pristine LLDPE can be expected to effectively reduce agricultural losses to disease when the films are applied as agricultural films, whilst the superior light transmittance and water-retaining properties of the composite films will boost agricultural production. Results presented suggest that multifunctional LLDPE/OLDHs nanocomposites show great promise as low cost agricultural plastic films.

Cu incorporated amorphous diamond like carbon (DLC) composites: An efficient electron field emitter over a wide range of temperature

NASA Astrophysics Data System (ADS)

Ahmed, Sk Faruque; Alam, Md Shahbaz; Mukherjee, Nillohit

2018-03-01

The effect of temperature on the electron field emission properties of copper incorporated amorphous diamond like carbon (a-Cu:DLC) thin films have been reported. The a-Cu:DLC thin films have been deposited on indium tin oxide (ITO) coated glass and silicon substrate by the radio frequency sputtering process. The chemical composition of the films was investigated using X-ray photoelectron spectroscopy and the micro structure was established using high resolution transmission electron microscopy. The sp2 and sp3 bonding ratio in the a-Cu:DLC have been analyzed by the Fourier transformed infrared spectroscopy studies. The material showed excellent electron field emission properties; which was optimized by varying the copper atomic percentage and temperature of the films. It was found that the threshold field and effective emission barrier were reduced significantly by copper incorporation as well as temperature and a detailed explanation towards emission mechanism has been provided.

Film/Adhesive Processing Module for Fiber-Placement Processing of Composites

NASA Technical Reports Server (NTRS)

Hulcher, A. Bruce

2007-01-01

An automated apparatus has been designed and constructed that enables the automated lay-up of composite structures incorporating films, foils, and adhesives during the automated fiber-placement process. This apparatus, denoted a film module, could be used to deposit materials in film or thin sheet form either simultaneously when laying down the fiber composite article or in an independent step.

Graphene-silica composite thin films as transparent conductors.

PubMed

Watcharotone, Supinda; Dikin, Dmitriy A; Stankovich, Sasha; Piner, Richard; Jung, Inhwa; Dommett, Geoffrey H B; Evmenenko, Guennadi; Wu, Shang-En; Chen, Shu-Fang; Liu, Chuan-Pu; Nguyen, SonBinh T; Ruoff, Rodney S

2007-07-01

Transparent and electrically conductive composite silica films were fabricated on glass and hydrophilic SiOx/silicon substrates by incorporation of individual graphene oxide sheets into silica sols followed by spin-coating, chemical reduction, and thermal curing. The resulting films were characterized by SEM, AFM, TEM, low-angle X-ray reflectivity, XPS, UV-vis spectroscopy, and electrical conductivity measurements. The electrical conductivity of the films compared favorably to those of composite thin films of carbon nanotubes in silica.

Graphene-silica Composite Thin Films as Transparent Conductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watcharotone,S.; Dikin, D.; Stankovich, S.

2007-01-01

Transparent and electrically conductive composite silica films were fabricated on glass and hydrophilic SiO{sub x}/silicon substrates by incorporation of individual graphene oxide sheets into silica sols followed by spin-coating, chemical reduction, and thermal curing. The resulting films were characterized by SEM, AFM, TEM, low-angle X-ray reflectivity, XPS, UV-vis spectroscopy, and electrical conductivity measurements. The electrical conductivity of the films compared favorably to those of composite thin films of carbon nanotubes in silica.

The influence of the precursor compositional ratio on Cu2ZnSnS4 films prepared by using sulfurization of the metallic precursor

NASA Astrophysics Data System (ADS)

Amal, Muhamad I.; Kim, Kyoo Ho

2013-12-01

Cu2ZnSnS4 (CZTS) films were prepared by using the sulfurization of sputtered metallic precursors. The compositional ratio of the CZTS films was slightly different compared to their initial metallic precursors due to elemental loss during annealing. The Cu/(Zn+Sn) ratio for the CZTS-1, CZTS-2 and CZTS-3 films were 0.91, 1.06 and 1.21, respectively. In addition, all films had a compositional ratio of Zn/Sn >1. The grain sizes of the CZTS films increased with increasing Cu ratio. X-ray diffraction and Raman spectroscopy showed that the CZTS films with an excess of copper and zinc had secondary phases of Cu2SnS3 and ZnS. The optical band gap and absorption coefficient for all CZTS films in the range of the experimental compositions were calculated to be 1.5 eV and >104 cm-1, respectively. The presence of secondary phases related to compositional ratio in the CZTS films influenced the electrical properties. The CZTS-1 film with a Cu-poor and Zn-rich composition whose a carrier concentration, an electrical mobility, and a resistivity values were 2.29 × 1018 cm-3, 10.29 cm2 V-1 s-1, 3.16 Ω cm, is the most suitable for solar-cell applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsieh, Bao-Yu; Kim, Jinwook; Li, Sibo

The photoacoustic effect has been broadly applied to generate high frequency and broadband acoustic waves using lasers. However, the efficient conversion from laser energy to acoustic power is required to generate acoustic waves with high intensity acoustic pressure (>10 MPa). In this study, we demonstrated laser generated high intensity acoustic waves using carbon nanofibers–polydimethylsiloxane (CNFs-PDMS) thin films. The average diameter of the CNFs is 132.7 ± 11.2 nm. The thickness of the CNFs film and the CNFs-PDMS composite film is 24.4 ± 1.43 μm and 57.9 ± 2.80 μm, respectively. The maximum acoustic pressure is 12.15 ± 1.35 MPa using a 4.2 mJ, 532 nm Nd:YAG pulsed laser. The maximum acoustic pressure using the CNFs-PDMSmore » composite was found to be 7.6-fold (17.62 dB) higher than using carbon black PDMS films. Furthermore, the calculated optoacoustic energy conversion efficiency K of the prepared CNFs-PDMS composite thin films is 15.6 × 10{sup −3 }Pa/(W/m{sup 2}), which is significantly higher than carbon black-PDMS thin films and other reported carbon nanomaterials, carbon nanostructures, and metal thin films. The demonstrated laser generated high intensity ultrasound source can be useful in ultrasound imaging and therapy.« less

Preparation and characterization of bio-nanocomposite films of agar and silver nanoparticles: laser ablation method.

PubMed

Rhim, Jong-Whan; Wang, Long-Feng; Lee, Yonghoon; Hong, Seok-In

2014-03-15

Silver nanoparticles (AgNPs) were prepared by a laser ablation method and composite films with the AgNPs and agar were prepared by solvent casting method. UV-vis absorbance test and transmission electron microscopy (TEM) analysis results revealed that non-agglomerated spherical AgNPs were formed by the laser ablation method. The surface color of the resulting agar/AgNPs films exhibited the characteristic plasmonic effect of the AgNPs with the maximum absorption peaks of 400-407 nm. X-ray diffraction (XRD) test results also exhibited characteristic AgNPs crystals with diffraction peaks observed at 2θ values of 38.39°, 44.49°, and 64.45°, which were corresponding to (111), (200), and (220) crystallographic planes of face-centered cubic (fcc) silver crystals, respectively. Thermogravimetric analysis (TGA) results showed that thermal stability of the agar/AgNPs composite films was increased by the inclusion of metallic silver. Water vapor barrier properties and surface hydrophobicity of the agar/AgNPs films increased slightly with the increase in AgNPs content but they were not statistically significant (p>0.05), while mechanical strength and stiffness of the composite films decreased slightly (p<0.05). The agar/AgNPs films exhibited distinctive antimicrobial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli O157:H7) bacterial pathogens. Copyright © 2014 Elsevier Ltd. All rights reserved.

Development of high J c Bi2223/Ag thick film materials prepared by heat treatment under low P O2

NASA Astrophysics Data System (ADS)

Takeda, Y.; Shimoyama, J.; Motoki, T.; Nakamura, S.; Nakashima, T.; Kobayashi, S.; Kato, T.

2018-07-01

In general, a dense and c-axis grain-oriented microstructure is desirable in order to achieve the high critical current properties of Bi2223 polycrystalline materials. On the other hand, our recent studies have shown that precise control of the chemical compositions of Bi2223 is also effective for the enhancement of intergrain J c. In this study, the development of Bi2223 thick film materials with high critical current properties was attempted by controlling both the microstructure and the chemical compositions. A high intergrain J c of ∼8 kA cm‑2 at 77 K of a film with ∼40 μm t was achieved by increasing the Pb substitution level for the Bi site and controlling the nonstoichiometric chemical compositions. Furthermore, it was revealed that an increase in the thickness enabled us to obtain high I c films suitable for practical applications. In contrast, there are still issues, especially in controlling the grain alignment at the inner part of the film, which suggests that the J c properties of thick film materials could be further improved by forming a more ideal microstructure, as realized in the Bi2223 filaments of multi-filamentary Ag-sheathed tapes.

Effect of different film packaging on microbial growth in minimally processed cactus pear (Opuntia ficus-indica).

PubMed

Palma, A; Mangia, N P; Fadda, A; Barberis, A; Schirra, M; D'Aquino, S

2013-01-01

Microorganisms are natural contaminants of fresh produce and minimally processed products, and contamination arises from a number of sources, including the environment, postharvest handling and processing. Fresh-cut products are particularly susceptible to microbial contaminations because of the changes occurring in the tissues during processing. In package gas composition of modified atmosphere packaging (MAP) in combination with low storage temperatures besides reducing physiological activity of packaged produce, can also delay pathogen growth. Present study investigated on the effect of MAPs, achieved with different plastic films, on microbial growth of minimally processed cactus pear (Opuntio ficus-indica) fruit. Five different plastic materials were used for packaging the manually peeled fruit. That is: a) polypropylene film (Termoplast MY 40 micron thickness, O2 transmission rate 300 cc/m2/24h); b) polyethylene film (Bolphane BHE, 11 micron thickness, O2 transmission rate 19000 cc/m2/24h); c) polypropylene laser-perforated films (Mach Packaging) with 8, 16 or 32 100-micron holes. Total aerobic psychrophilic, mesophilic microorganisms, Enterobacteriaceae, yeast, mould populations and in-package CO2, O2 and C2H4 were determined at each storage time. Different final gas compositions, ranging from 7.8 KPa to 17.1 KPa O2, and 12.7 KPa to 2.6 KPa CO2, were achieved with MY and micro perforated films, respectively. Differences were detected in the mesophilic, Enterobacteriaceae and yeast loads, while no difference was detected in psychrophilic microorganisms. At the end of storage, microbial load in fruits sealed with MY film was significantly lower than in those sealed with BHE and micro perforated films. Furthermore, fruits packed with micro-perforated films showed the highest microbial load. This occurrence may in part be related to in-package gas composition and in part to a continuous contamination of microorganisms through micro-holes.

Utilization of flax (Linum usitatissimum) cellulose nanocrystals as reinforcing material for chitosan films.

PubMed

Mujtaba, Muhammad; Salaberria, Asier M; Andres, María A; Kaya, Murat; Gunyakti, Ayse; Labidi, Jalel

2017-11-01

Use of plastic based packaging tools is causing both health and economic problems. To overcome this situation, researchers are focusing on the use of different biomaterials such as chitosan and cellulose. The current study was conducted to check the effect of flax (Linum usitatissimum) cellulose nanocrystals (CNC) on mechanical and barrier properties of chitosan-based films. CNC was incorporated in different concentrations (5, 10, 20 and 30%). CNC was isolated from flax fiber using acid hydrolysis method. Tensile strength (TS) and young modulus (YM) values increased with the increase of CNC concentration. Chitosan film with 20% CNC revealed the highest YM value as 52.35MPa. No significant improvement was recorded in water vapor permeability due to overall lower film crystallinity. All the films were observed to be transparent up to an acceptable level. SEM and AFM analysis confirmed the homogeneity of films. A gradual enhancement was recorded in the antimicrobial activity of chitosan/CNC composite films. No significant improvement revealed in the thermal stability of composites. Copyright © 2017 Elsevier B.V. All rights reserved.

Metal Composition and Polyethylenimine Doping Capacity Effects on Semiconducting Metal Oxide-Polymer Blend Charge Transport.

PubMed

Huang, Wei; Guo, Peijun; Zeng, Li; Li, Ran; Wang, Binghao; Wang, Gang; Zhang, Xinan; Chang, Robert P H; Yu, Junsheng; Bedzyk, Michael J; Marks, Tobin J; Facchetti, Antonio

2018-04-25

Charge transport and film microstructure evolution are investigated in a series of polyethylenimine (PEI)-doped (0.0-6.0 wt%) amorphous metal oxide (MO) semiconductor thin film blends. Here, PEI doping generality is broadened from binary In 2 O 3 to ternary (e.g., In+Zn in IZO, In+Ga in IGO) and quaternary (e.g., In+Zn+Ga in IGZO) systems, demonstrating the universality of this approach for polymer electron doping of MO matrices. Systematic comparison of the effects of various metal ions on the electronic transport and film microstructure of these blends are investigated by combined thin-film transistor (TFT) response, AFM, XPS, XRD, X-ray reflectivity, and cross-sectional TEM. Morphological analysis reveals that layered MO film microstructures predominate in PEI-In 2 O 3 , but become less distinct in IGO and are not detectable in IZO and IGZO. TFT charge transport measurements indicate a general coincidence of a peak in carrier mobility (μ peak ) and overall TFT performance at optimal PEI doping concentrations. Optimal PEI loadings that yield μ peak values depend not only on the MO elemental composition but also, equally important, on the metal atomic ratios. By investigating the relationship between the MO energy levels and PEI doping by UPS, it is concluded that the efficiency of PEI electron-donation is highly dependent on the metal oxide matrix work function in cases where film morphology is optimal, as in the IGO compositions. The results of this investigation demonstrate the broad generality and efficacy of PEI electron doping applied to electronically functional metal oxide systems and that the resulting film microstructure, morphology, and energy level modifications are all vital to understanding charge transport in these amorphous oxide blends.

Effect of Target Composition and Sputtering Deposition Parameters on the Functional Properties of Nitrogenized Ag-Permalloy Flexible Thin Films Deposited on Polymer Substrates

PubMed Central

Wang, Qun; Jin, Xin

2018-01-01

We report the first results of functional properties of nitrogenized silver-permalloy thin films deposited on polyethylene terephthalic ester {PETE (C10H8O4)n} flexible substrates by magnetron sputtering. These new soft magnetic thin films have magnetization that is comparable to pure Ni81Fe19 permalloy films. Two target compositions (Ni76Fe19Ag5 and Ni72Fe18Ag10) were used to study the effect of compositional variation and sputtering parameters, including nitrogen flow rate on the phase evolution and surface properties. Aggregate flow rate and total pressure of Ar+N2 mixture was 60 sccm and 0.55 Pa, respectively. The distance between target and the substrate was kept at 100 mm, while using sputtering power from 100–130 W. Average film deposition rate was confirmed at around 2.05 nm/min for argon atmosphere and was reduced to 1.8 nm/min in reactive nitrogen atmosphere. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, vibrating sample magnetometer, and contact angle measurements were used to characterize the functional properties. Nano sized character of films was confirmed by XRD and SEM. It is found that the grain size was reduced by the formation of nitride phase, which in turns enhanced the magnetization and lowers the coercivity. Magnetic field coupling efficiency limit was determined from 1.6–2 GHz frequency limit. The results of comparable magnetic performance, lowest magnetic loss, and highest surface free energy, confirming that 15 sccm nitrogen flow rate at 115 W is optimal for producing Ag-doped permalloy flexible thin films having excellent magnetic field coupling efficiency. PMID:29562603

A Low Temperature, Solution-Processed Poly(4-vinylphenol), YO(x) Nanoparticle Composite/Polysilazane Bi-Layer Gate Insulator for ZnO Thin Film Transistor.

PubMed

Shin, Hyeonwoo; Kang, Chan-Mo; Chae, Hyunsik; Kim, Hyun-Gwan; Baek, Kyu-Ha; Choi, Hyoung Jin; Park, Man-Young; Do, Lee-Mi; Lee, Changhee

2016-03-01

Low temperature, solution-processed metal oxide thin film transistors (MEOTFTs) have been widely investigated for application in low-cost, transparent, and flexible electronics. To enlarge the application area, solution-processed gate insulators (GI) have been investigated in recent years. We investigated the effects of the organic/inorganic bi-layer GI to ZnO thin film transistors (TFTs). PVP, YO(x) nanoparticle composite, and polysilazane bi-layer showed low leakage current (-10(-8) A/cm2 in 2 MV), which are applicable in low temperature processed MEOTFTs. Polysilazane was used as an interlayer between ZnO and PVP, YO(x) nanoparticle composite as a good charge transport interface with ZnO. By applying the PVP, YO(x), nanoparticle composite/polysilazane bi-layer structure to ZnO TFTs, we successfully suppressed the off current (I(off)) to -10(-11) and fabricated good MEOTFTs in 180 degrees C.

Effect of Zr Doping on Structural and Ferroelectric Properties of Lead-Free Bi0.5(Na0.80K0.20)0.5TiO3 Films

NASA Astrophysics Data System (ADS)

Quan, Ngo Duc; Hung, Vu Ngoc; Dung, Dang Duc

2017-10-01

Environmentally friendly lead-free Bi0.5(Na0.80K0.20)0.5(Ti1- x Zr x )O3 (BNKT- xZr) ferroelectric films with Zr4+ doping concentration x in the range from 0 to 0.05 have been grown on Pt/Ti/SiO2/Si substrates via chemical solution deposition. The effects of Zr4+ substitution on the crystal structure and ferroelectric properties of the films were investigated. X-ray diffraction data revealed that the BNKT- xZr films possessed rhombohedral and tetragonal symmetries at a morphotropic phase boundary when a small amount of Zr4+ doping was added. P- E hysteresis loops typical of ferroelectric materials were observed for all compositions. Zr4+ substituted for Ti4+ in the BNKT- xZr films and remarkably enhanced the ferroelectric properties. The remanent ( P r) and maximum polarization ( P m) reached their highest values of 14.0 μC/cm2 and 35.7 μC/cm2, respectively, at x = 0.02. These values, which are equivalent to the highest P r and P m values in previous reports on lead-free films with different compositions, compare well with those of Pb(Zr,Ti)O3 (PZT) films. Therefore, BNKT- xZr films with optimal Zr4+ concentration could substitute for PZT films in lead-free piezo-microelectromechanical systems (MEMS) devices.

Enhanced Fluorescence Properties of Carbon Dots in Polymer Films

PubMed Central

Liu, Yamin; Wang, Ping; Shiral Fernando, K. A.; LeCroy, Gregory E.; Maimaiti, Halidan; Harruff-Miller, Barbara A.; Lewis, William K.; Bunker, Christopher E.; Hou, Zhi-Ling; Sun, Ya-Ping

2016-01-01

Carbon dots of small carbon nanoparticles surface-functionalized with 2,2′-(ethylenedioxy)bis(ethylamine) (EDA) were synthesized, and the as-synthesized sample was separated on an aqueous gel column to obtain fractions of the EDA-carbon dots with different fluorescence quantum yields. As already discussed in the literature, the variations in fluorescence performance among the fractions were attributed to the different levels and/or effectiveness of the surface functionalization-passivation in the carbon dots. These fractions, as well as carbon nanoparticles without any deliberate surface functionalization, were dispersed into poly(vinyl alcohol) (PVA) for composite films. In the PVA film matrix, the carbon dots and nanoparticles exhibited much enhanced fluorescence emissions in comparison with their corresponding aqueous solutions. The increased fluorescence quantum yields in the films were determined quantitatively by using a specifically designed and constructed film sample holder in the emission spectrometer. The observed fluorescence decays of the EDA-carbon dots in film and in solution were essentially the same, suggesting that the significant enhancement in fluorescence quantum yields from solution to film is static in nature. Mechanistic implications of the results, including a rationalization in terms of the compression effect on the surface passivation layer (similar to a soft corona) in carbon dots when embedded in the more restrictive film environment resulting in more favorable radiative recombinations of the carbon particle surface-trapped electrons and holes, and also potential technological applications of the brightly fluorescent composite films are highlighted and discussed. PMID:28133537

Facile Fabrication of Gradient Surface Based on (meth)acrylate Copolymer Films

NASA Astrophysics Data System (ADS)

Zhang, Y.; Yang, H.; Wen, X.-F.; Cheng, J.; Xiong, J.

2016-08-01

This paper describes a simple and economic approach for fabrication of surface wettability gradient on poly(butyl acrylate - methyl methacrylate) [P (BA-MMA)] and poly(butyl acrylate - methyl methacrylate - 2-hydroxyethyl methacrylate) [P (BA-MMA-HEMA)] films. The (meth)acrylate copolymer [including P (BA-MMA) and P (BA-MMA-HEMA)] films are hydrolyzed in an aqueous solution of NaOH and the transformation of surface chemical composition is achieved by hydrolysis in NaOH solution. The gradient wetting properties are generated based on different functional groups on the P (BA-MMA) and P (BA-MMA-HEMA) films. The effects of both the surface chemical and surface topography on wetting of the (meth)acrylate copolymer film are discussed. Surface chemical composition along the materials length is determined by XPS, and surface topography properties of the obtained gradient surfaces are analyzed by FESEM and AFM. Water contact angle system (WCAs) results show that the P (BA-MMA-HEMA) films provide a larger slope of the gradient wetting than P (BA-MMA). Moreover, this work demonstrates that the gradient concentration of chemical composition on the poly(meth) acrylate films is owing to the hydrolysis processes of ester group, and the hydrolysis reactions that have negligible influence on the surface morphology of the poly(meth) acrylate films coated on the glass slide. The gradient wettability surfaces may find broad applications in the field of polymer coating due to the compatibility of (meth) acrylate polymer.

Metallic nanoislands on graphene: A metamaterial for chemical, mechanical, optical, and biological applications.

PubMed

Marin, Brandon C; Ramirez, Julian; Root, Samuel E; Aklile, Eden; Lipomi, Darren J

2017-01-01

Graphene decorated with metallic nanoparticles exhibits electronic, optical, and mechanical properties that neither the graphene nor the metal possess alone. These composite films have electrical conductivity and optical properties that can be modulated by a range of physical, chemical, and biological signals. Such properties are controlled by the morphology of the nanoisland films, which can be deposited on graphene using a variety of techniques, including in situ chemical synthesis and physical vapor deposition. These techniques produce non-random (though loosely defined) morphologies, but can be combined with lithography to generate deterministic patterns. Applications of these composite films include chemical sensing and catalysis, energy storage and transport (including photoconductivity), mechanical sensing (using a highly sensitive piezroresistive effect), optical sensing (including so-called "piezoplasmonic" effects), and cellular biophysics (i.e sensing the contractions of cardiomyocytes and myoblasts).

Antimicrobial evaluation of novel poly-lactic acid based nanocomposites incorporated with bioactive compounds in-vitro and in refrigerated vacuum-packed cooked sausages.

PubMed

Rezaeigolestani, Mohammadreza; Misaghi, Ali; Khanjari, Ali; Basti, Afshin Akhondzadeh; Abdulkhani, Ali; Fayazfar, Samira

2017-11-02

Biodegradability and antimicrobial activity of food packaging materials are among the most attractive parameters in modern food industries. In order to develop biodegradable poly-lactic acid (PLA) film to antibacterial nanocomposites, different concentration of Zataria multiflora Bioss. essential oil (ZME), propolis ethanolic extract (PEE) and cellulose nanofiber (CNF) were incorporated to the polymer by solvent casting method. The resulting films were characterized by mechanical and physical tests and their antimicrobial application was evaluated in-vitro against four common foodborne pathogens and in vacuum-packed cooked sausages during refrigerated storage. Mechanical examination revealed that addition of ZME and PEE made films more flexible and incorporation of CNF improved almost all mechanical parameters tested. Moreover, according to physical analysis, incorporation of 0.5% v/v ZME to the composite primary solutions improved water vapor permeability of the resulting films. Almost all of the active films were effective against the tested bacteria except for PLA/PEE films, and maximum antibacterial effects recorded for the films containing both ZME and PEE. Based on the microbiological and sensory evaluation of the sausages, all of the PLA/1%ZME/PEE composites increased the shelf life to >40days. The results indicate that incorporation of natural antimicrobial substances such as ZME and PEE to packaging material could be an interesting approach in development of active packaging material without significant negative effect on polymer technical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

Ni-coated CaCu3Ti4O12/low density polyethylene composite material with ultra-high dielectric permittivity

NASA Astrophysics Data System (ADS)

Gao, L.; Wang, X.; Chen, Y.; Chi, Q. G.; Lei, Q. Q.

2015-08-01

We report a novel low-density polyethylene (LDPE) composite filled with nickel-coated CaCu3Ti4O12 ceramic (denoted as CCTO@Ni), prepared by a melt mixing technique, and its prominent dielectric characteristics. The effects of magnetic field treatment on the dielectric properties of CCTO@Ni/LDPE composite films with a low filler concentration of 10 vol.% were investigated. Our results show that the dielectric permittivity, loss tangent, and conductivity of the LDPE composite films initially improved and then decreased with increasing treatment time under the applied magnetic field. Magnetic field treatment for 60 min led to an ultra-high dielectric permittivity value of 1.57 × 104, four orders of magnitude higher than that of the pure LDPE material. Our results indicate that the magnetic treatment may have induced a percolation effect and enhanced the interfacial polarization of the CCTO@Ni/LDPE composite, resulting in the observed changes in its dielectric properties.

Effect of Halide Composition on the Photochemical Stability of Perovskite Photovoltaic Materials.

PubMed

Misra, Ravi K; Ciammaruchi, Laura; Aharon, Sigalit; Mogilyansky, Dmitry; Etgar, Lioz; Visoly-Fisher, Iris; Katz, Eugene A

2016-09-22

The photochemical stability of encapsulated films of mixed halide perovskites with a range of MAPb(I 1-x Br x ) 3 (MA=methylammonium) compositions (solid solutions) was investigated under accelerated stressing using concentrated sunlight. The relevance of accelerated testing to standard operational conditions of solar cells was confirmed by comparison to degradation experiments under outdoor sunlight exposure. We found that MAPbBr 3 films exhibited no degradation, while MAPbI 3 and mixed halide MAPb(I 1-x Br x ) 3 films decomposed yielding crystallization of inorganic PbI 2 accompanied by degradation of the perovskite solar light absorption, with faster absorption degradation in mixed halide films. The crystal coherence length was found to correlate with the stability of the films. We postulate that the introduction of Br into the mixed halide solid solution stressed its structure and induced more structural defects and/or grain boundaries compared to pure halide perovskites, which might be responsible for the accelerated degradation. Hence, the cause for accelerated degradation may be the increased defect density rather than the chemical composition of the perovskite materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced off-resonance magnetoelectric response in laser annealed PZT thick film grown on magnetostrictive amorphous metal substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palneedi, Haribabu; Functional Ceramics Group, Korea Institute of Materials Science; Maurya, Deepam

2015-07-06

A highly dense, 4 μm-thick Pb(Zr,Ti)O{sub 3} (PZT) film is deposited on amorphous magnetostrictive Metglas foil (FeBSi) by granule spray in vacuum process at room temperature, followed by its localized annealing with a continuous-wave 560 nm ytterbium fiber laser radiation. This longer-wavelength laser radiation is able to anneal the whole of thick PZT film layer without any deteriorative effects, such as chemical reaction and/or atomic diffusion, at the interface and crystallization of amorphous Metglas substrate. Greatly enhanced dielectric and ferroelectric properties of the annealed PZT are attributed to its better crystallinity and grain growth induced by laser irradiation. As a result, amore » colossal off-resonance magnetoelectric (ME) voltage coefficient that is two orders of magnitude larger than previously reported output from PZT/Metglas film-composites is achieved. The present work addresses the problems involved in the fabrication of PZT/Metglas film-composites and opens up emerging possibilities in employing piezoelectric materials with low thermal budget substrates (suitable for integrated electronics) and designing laminate composites for ME based devices.« less

Flexible barrier film, method of forming same, and organic electronic device including same

DOEpatents

Blizzard, John; Tonge, James Steven; Weidner, William Kenneth

2013-03-26

A flexible barrier film has a thickness of from greater than zero to less than 5,000 nanometers and a water vapor transmission rate of no more than 1.times.10.sup.-2 g/m.sup.2/day at 22.degree. C. and 47% relative humidity. The flexible barrier film is formed from a composition, which comprises a multi-functional acrylate. The composition further comprises the reaction product of an alkoxy-functional organometallic compound and an alkoxy-functional organosilicon compound. A method of forming the flexible barrier film includes the steps of disposing the composition on a substrate and curing the composition to form the flexible barrier film. The flexible barrier film may be utilized in organic electronic devices.

Nanodiamond embedded ta-C composite film by pulsed filtered vacuum arc deposition from a single target

NASA Astrophysics Data System (ADS)

Iyer, Ajai; Etula, Jarkko; Ge, Yanling; Liu, Xuwen; Koskinen, Jari

2016-11-01

Detonation Nanodiamonds (DNDs) are known to have sp3 core, sp2 shell, small size (few nm) and are gaining importance as multi-functional nanoparticles. Diverse methods have been used to form composites, containing detonation nanodiamonds (DNDs) embedded in conductive and dielectric matrices for various applications. Here we show a method, wherein DND-ta-C composite film, consisting of DNDs embedded in ta-C matrix have been co-deposited from the same cathode by pulsed filtered cathodic vacuum arc method. Transmission Electron Microscope analysis of these films revel the presence of DNDs embedded in the matrix of amorphous carbon. Raman spectroscopy indicates that the presence of DNDs does not adversely affect the sp3 content of DND-ta-C composite film compared to ta-C film of same thickness. Nanoindentation and nanowear tests indicate that DND-ta-C composite films possess improved mechanical properties in comparison to ta-C films of similar thickness.

Electroplated Fe-Co-Ni films prepared from deep-eutectic-solvent-based plating baths

NASA Astrophysics Data System (ADS)

Yanai, Takeshi; Shiraishi, Kotaro; Akiyoshi, Toshiki; Azuma, Keita; Watanabe, Yoshimasa; Ohgai, Takeshi; Morimura, Takao; Nakano, Masaki; Fukunaga, Hirotoshi

2016-05-01

We fabricated soft magnetic films from DES-based plating baths, and investigated magnetic properties of the plated films. The plating baths were obtained by stirring the mixture of choline chloride, ethylene glycol, FeCl2 ṡ 4H2O, NiCl2 ṡ 6H2O and CoCl2 ṡ 6H2O. The composition of the electroplated film depended on the amount of the reagent in the plating bath, and we consequently obtained the films with various composition. The current efficiency of the plating process shows high values (> 88 %) in the wide composition range. The soft magnetic films with low coercivity were obtained at the Fe compositions of ≈ 30 at.% and > 80 at.%, and we found that low coercivity could be realized by the control of the film composition. We also found that the Fe-rich films prepared from DES-based plating bath have some advantages as a soft magnetic phase for a nanocomposite magnet due to their high saturation magnetization and very fine crystal structure.

Enhancement of the output emission efficiency of thin-film photoluminescence composite structures based on PbSe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anisimova, N. P.; Tropina, N. E., E-mail: Mazina_ne@mail.ru; Tropin, A. N.

2010-12-15

The opportunity to increase the output emission efficiency of PbSe-based photoluminescence structures by depositing an antireflection layer is analyzed. A model of a three-layer thin film where the central layer is formed of a composite medium is proposed to calculate the reflectance spectra of the system. In von Bruggeman's approximation of the effective medium theory, the effective permittivity of the composite layer is calculated. The model proposed in the study is used to calculate the thickness of the arsenic chalcogenide (AsS{sub 4}) antireflection layer. The optimal AsS{sub 4} layer thickness determined experimentally is close to the results of calculation, andmore » the corresponding gain in the output photoluminescence efficiency is as high as 60%.« less

A Novel Method for Fabricating Wearable, Piezoresistive, and Pressure Sensors Based on Modified-Graphite/Polyurethane Composite Films

PubMed Central

He, Yin; Li, Wei; Yang, Guilin; Liu, Hao; Lu, Junyu; Zheng, Tongtong; Li, Xiaojiu

2017-01-01

A wearable, low-cost, highly repeatable piezoresistive sensor was fabricated by the synthesis of modified-graphite and polyurethane (PU) composites and polydimethylsiloxane (PDMS). Graphite sheets functionalized by using a silane coupling agent (KH550) were distributed in PU/N,N-dimethylformamide (DMF) solution, which were then molded to modified-graphite/PU (MG/PU) composite films. Experimental results show that with increasing modified-graphite content, the tensile strength of the MG/PU films first increased and then decreased, and the elongation at break of the composite films showed a decreasing trend. The electrical conductivity of the composite films can be influenced by filler modification and concentration, and the percolation threshold of MG/PU was 28.03 wt %. Under liner uniaxial compression, the 30 wt % MG/PU composite films exhibited 0.274 kPa−1 piezoresistive sensitivity within the range of low pressure, and possessed better stability and hysteresis. The flexible MG/PU composite piezoresistive sensors have great potential for body motion, wearable devices for human healthcare, and garment pressure testing. PMID:28773047

In Situ Oxidation Synthesis of p-Type Composite with Narrow-Bandgap Small Organic Molecule Coating on Single-Walled Carbon Nanotube: Flexible Film and Thermoelectric Performance.

PubMed

Gao, Caiyan; Chen, Guangming

2018-03-01

Although composites of organic polymers or n-type small molecule/carbon nanotube (CNT) have achieved significant advances in thermoelectric (TE) applications, p-type TE composites of small organic molecules as thick surface coating layers on the surfaces of inorganic nanoparticles still remain a great challenge. Taking advantage of in situ oxidation reaction of thieno[3,4-b]pyrazine (TP) into TP di-N-oxide (TPNO) on single-walled CNT (SWCNT) surface, a novel synthesis strategy is proposed to achieve flexible films of TE composites with narrow-bandgap (1.19 eV) small molecule coating on SWCNT surface. The TE performance can be effectively enhanced and conveniently tuned by poly(sodium-p-styrenesulfonate) content, TPNO/SWCNT mass ratio, and posttreatment by various polar solvents. The maximum of the composite power factor at room temperature is 29.4 ± 1.0 µW m -1 K -2 . The work presents a way to achieve flexible films of p-type small organic molecule/inorganic composites with clear surface coating morphology for TE application. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrodeposition of nickel-iridium alloy films from aqueous solutions

NASA Astrophysics Data System (ADS)

Wu, Wangping; Jiang, Jinjin; Jiang, Peng; Wang, Zhizhi; Yuan, Ningyi; Ding, Jianning

2018-03-01

Nickel-iridium (Ni-Ir) alloy films were electrodeposited from aqueous solutions on copper substrates under galvanostatic conditions. The effects of bath composition and deposition time on the faradaic efficiency (FE), partial current densities, chemical composition, morphology and crystallographic structure of the films were studied. The results show that the Ni-Ir alloys with Ir content as high as 37 at% and FE as high as 44% were obtained. Increase in concentration of citric acid had little or no effect on the composition of the alloys, but resulted in a significant decrease in FE and partial current densities of Ni and Ir. The FE and the partial current density of Ni slightly decreased with increasing Ir3+ concentration, however, Ir content increased while partial current density of Ir remained stable. The increase of Ni2+ concentration could result in the increase of the FE and the rate of Ni-Ir deposition, and even no cracks formed on the surface. The surface average roughness and root mean square roughness of the film were 6.8 ± 0.3 nm and 5.4 ± 0.3 nm, respectively. The mixture phases contained significant amounts of Ni oxides and a small amount of metallic Ni, Ir and Ir oxides on the surface. After argon ion sputter cleaning, the film was mainly composed of metallic Ni and Ir. The film consisted of the amorphous and nanocrystalline phases. The Ni content in the deposits was higher than that in the electrolyte, the co-deposition of Ni-Ir alloy was a normal deposition.

Fabrication of Monolithic Sapphire Membranes for High Tc Bolometer Array Development

NASA Technical Reports Server (NTRS)

Pugel, D. E.; Lakew, B.; Aslam, S.; Wang, L.

2003-01-01

This paper examines the effectiveness of Pt/Cr thin film masks for the architecture of monolithic membrane structures in r-plane sapphire. The development of a pinhole-free Pt/Cr composite mask that is resistant to hot H2SO4:H3PO4 etchant, will lead to the fabrication of smooth sapphire membranes whose surfaces are well-suited for the growth of low-noise high Tc films. In particular, the relationship of thermal annealing conditions on the Pt/Cr composite mask system to: (1) changes in the surface morphology and elemental concentration of the Pt/Cr thin film layers and (2) etch pit formation on the sapphire surface will be presented.

Improved luminescence intensity and stability of thermal annealed ZnO incorporated Alq3 composite films.

PubMed

Cuba, M; Muralidharan, G

2015-11-01

The 30 wt% of ZnO (weight percentage of ZnO has been optimised) incorporated tris- (8-hydroxyquinoline)aluminum (Alq3) has been synthesised and coated on to glass substrates using dip coating method. The structural and optical properties of the Alq3/ZnO composite film after thermal annealing from 50 to 300 °C insteps 50° has been studied and reported. XRD pattern reveals the presence of crystalline ZnO in all the annealed films. The films annealed above 150 °C reveal the presence of crystalline Alq3 along with crystalline ZnO. The FTIR spectra confirm the presence of hydroxyquinoline and ZnO vibration in all the annealed composite films. The composite films annealed above 150 °C show a partial sublimation and degradation of hydroxyquinoline compounds. The ZnO incorporated composite films (Alq3/ZnO) exhibit two emission peaks, one corresponding to ZnO at 487 nm and another at 513 nm due to Alq3. The films annealed at 200 °C exhibit maximum photoluminescence (PL) intensity than pristine film at 513 nm when excited at 390 nm.

Deposition of PTFE thin films by ion beam sputtering and a study of the ion bombardment effect

NASA Astrophysics Data System (ADS)

He, J. L.; Li, W. Z.; Wang, L. D.; Wang, J.; Li, H. D.

1998-02-01

Ion beam sputtering technique was employed to prepare thin films of Polytetrafluroethylene (PTFE). Simultaneous ion beam bombardment during film growth was also conducted in order to study the bombardment effects. Infrared absorption (IR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis was used to evaluate the material's integrity. It was found that PTFE thin films could be grown at room temperature by direct sputtering of a PTFE target. The film's composition and structure were shown to be dependent on the sputtering energy. Films deposited by single sputtering at higher energy (˜1500 eV) were structurally quite similar to the original PTFE material. Simultaneous ion beam bombarding during film growth caused defluorination and structural changes. Mechanism for sputtering deposition of such a polymeric material is also discussed.

Ceramics Derived from Organo-Metallic Precursors

DTIC Science & Technology

1991-10-01

spraying, and roller-coating may also be used to good effect . The films deposited by any of these techniques are ready to be fired immediately...films. The wet chemical route offers great potential for highly cost- effective processing; and the critical issue for its wide-scale implementation is...glasses and subsequently to crystallize single phase HTSC materials. The fourth composition, 4223, was made in order to test the effect of Bi on glass

Optical studies of CdSe/PVA nanocomposite films

NASA Astrophysics Data System (ADS)

Kushwaha, Kamal Kumar; Ramrakhaini, Meera

2018-05-01

The nanocomposite films of CdSe nanocrystals in polyvinyl alcohol (PVA) matrix were synthesized by environmental friendly chemical method. These composites were characterized by X-ray diffraction which indicates the hexagonal crystalline structure of CdSe with crystal size up to a few nm. The crystal size is found to decrease by increasing PVA Concentration. The photoluminescence (PL) characteristics of these composite films with varying concentration of PVA as well as Cd2+ content have been investigated. The PL peak of CdSe was observed at 510 nm and higher intensity is observed by increasing PVA concentration without any change in position of PL peak. Due to proper passivation of surface states non-radiative transition are reduced which enhance the PL intensity. By increasing concentration of Cd2+ content in the CdSe/PVA nanocomposite films, smaller CdSe nanocrystals were obtained giving higher intensity and blue shift in the PL peak due to enhanced oscillator strength and quantum confinement effect. The PL peak in green and blue region makes these composite films promising materials for optical display devices. The Refractive index of these composites was also measured at sodium line with the help of Abee's refractometer and was found in the range of 2.20-2.45. It is seen that refractive index varies with polymer concentration. This may be useful for their potential application in anti-reflection coating, display devices and optical sensors.

Low-temperature growth and electronic structures of ambipolar Yb-doped zinc tin oxide transparent thin films

NASA Astrophysics Data System (ADS)

Oh, Seol Hee; Ferblantier, Gerald; Park, Young Sang; Schmerber, Guy; Dinia, Aziz; Slaoui, Abdelilah; Jo, William

2018-05-01

The compositional dependence of the crystal structure, optical transmittance, and surface electric properties of the zinc tin oxide (Zn-Sn-O, shortened ZTO) thin films were investigated. ZTO thin films with different compositional ratios were fabricated on glass and p-silicon wafers using radio frequency magnetron sputtering. The binding energy of amorphous ZTO thin films was examined by a X-ray photoelectron spectroscopy. The optical transmittance over 70% in the visible region for all the ZTO films was observed. The optical band gap of the ZTO films was changed as a result of the competition between the Burstein-Moss effect and renormalization. An electron concentration in the films and surface work function distribution were measured by a Hall measurement and Kelvin probe force microscopy, respectively. The mobility of the n- and p-type ZTO thin films have more than 130 cm2/V s and 15 cm2/V s, respectively. We finally constructed the band structure which contains band gap, work function, and band edges such as valence band maximum and conduction band minimum of ZTO thin films. The present study results suggest that the ZTO thin film is competitive compared with the indium tin oxide, which is a representative material of the transparent conducting oxides, regarding optoelectronic devices applications.

Photoflash thermal diffusivity measurement of carbon nanotube-filled PVDF composite at low temperature

NASA Astrophysics Data System (ADS)

Moksin, M. M.; Haydari, M.; Husin, M. S.; Yahya, N.; Azmi, B. Z.

2013-09-01

The suitability of a simple photoflash technique was further examined in the measurement of thermal diffusivity of nanotube-filled polyvinylidene difluoride (PVDF) film composites at low temperature. The effect of temperature and carbon nanotube (CNT) composition in PVDF composite on its thermal diffusivity is presented as equivalent to the effect of changing thermal phonon mean free path. It is done by assuming no other thermal carrier effects other than from phonons detected during measurement by using photoflash technique. The results show that thermal diffusivity of CNT-filled PVDF film composites was found to have consistently increased with increasing the CNT concentration or decreasing temperature, as in the case of insulators with dominant phonon thermal carriers. At any particular temperature, a dramatic increase in thermal diffusivity was noticed at the beginning as the CNT concentration was systematically increased up to a 1% turning point, from which the thermal diffusivity increased further at a much smaller rate with the CNT addition up to 10%. The thermal diffusivity of the samples was in the range of about (10-35) × 10- 8 m2/s depending on the temperature and the CNT concentration of the composites.

Tribological properties of sputtered MoS sub 2 films in relation to film morphology

NASA Technical Reports Server (NTRS)

Spalvins, T.

1980-01-01

Thin sputter deposited MoS2 films in the 2000 to 6000 A thickness range have shown excellent lubricating properties, when sputtering parameters and substrate conditions are properly selected and precisely controlled. The lubricating properties of sputtered MoS2 films are strongly influenced by their crystalline-amorphous structure, morphology and composition. The coefficient of friction can range from 0.04 which is effective lubrication to 0.4 which reflects an absence of lubricating properties. Visual screening and slight wiping of the as-sputtered MoS2 film can identify the integrity of the film. An acceptable film displays a black-sooty surface appearance whereas an unacceptable film has a highly reflective, gray surface and the film is hard and brittle.

Fabrication and photoelectrochemical properties of ZnS/Au/TiO2 nanotube array films.

PubMed

Zhu, Yan-Feng; Zhang, Juan; Xu, Lu; Guo, Ya; Wang, Xiao-Ping; Du, Rong-Gui; Lin, Chang-Jian

2013-03-21

A highly ordered TiO(2) nanotube array film was fabricated by an anodic oxidation method. The film was modified by Au nanoparticles (NPs) formed by a deposition-precipitation technique and was covered with a thin ZnS shell prepared by a successive ionic layer adsorption and reaction (SILAR) method. The photoelectrochemical properties of the prepared ZnS/Au/TiO(2) composite film were evaluated by incident photon-to-current conversion efficiency (IPCE), and photopotential and electrochemical impedance spectroscopy (EIS) measurements under white light illumination. The results indicated that the Au NPs could expand the light sensitivity range of the film and suppress the electron-hole recombination, and the ZnS shell could inhibit the leakage of photogenerated electrons from the surface of Au NPs to the ZnS/electrolyte interface. When the 403 stainless steel in a 0.5 M NaCl solution was coupled to the ZnS/Au/TiO(2) nanotube film photoanode under illumination, its potential decreased by 400 mV, showing that the composite film had a better photocathodic protection effect on the steel than that of a pure TiO(2) nanotube film.

Effect of negative bias on the composition and structure of the tungsten oxide thin films deposited by magnetron sputtering

NASA Astrophysics Data System (ADS)

Wang, Meihan; Lei, Hao; Wen, Jiaxing; Long, Haibo; Sawada, Yutaka; Hoshi, Yoichi; Uchida, Takayuki; Hou, Zhaoxia

2015-12-01

Tungsten oxide thin films were deposited at room temperature under different negative bias voltages (Vb, 0 to -500 V) by DC reactive magnetron sputtering, and then the as-deposited films were annealed at 500 °C in air atmosphere. The crystal structure, surface morphology, chemical composition and transmittance of the tungsten oxide thin films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV-vis spectrophotometer. The XRD analysis reveals that the tungsten oxide films deposited at different negative bias voltages present a partly crystallized amorphous structure. All the films transfer from amorphous to crystalline (monoclinic + hexagonal) after annealing 3 h at 500 °C. Furthermore, the crystallized tungsten oxide films show different preferred orientation. The morphology of the tungsten oxide films deposited at different negative bias voltages is consisted of fine nanoscale grains. The grains grow up and conjunct with each other after annealing. The tungsten oxide films deposited at higher negative bias voltages after annealing show non-uniform special morphology. Substoichiometric tungsten oxide films were formed as evidenced by XPS spectra of W4f and O1s. As a result, semi-transparent films were obtained in the visible range for all films deposited at different negative bias voltages.

Significantly improved dielectric performances of nanocomposites via loading two-dimensional core-shell structure Bi2Te3@SiO2 nanosheets

NASA Astrophysics Data System (ADS)

Chen, Jianwen; Wang, Xiucai; Yu, Xinmei; Fan, Yun; Duan, Zhikui; Jiang, Yewen; Yang, Faquan; Zhou, Yuexia

2018-07-01

Polymer/semiconductor-insulator nanocomposites can display high dielectric constants with a relatively low dissipation factor under low electric fields, and thus seem to promising for high energy density capacitors. Here, a novel nanocomposite films is developed by loading two-dimensional (2D) core-shell structure Bi2Te3@SiO2 nanosheets in the poly (vinylidene fluoride-hexafluoro propylene) (P(VDF-HFP)) polymer matrix. The 2D Bi2Te3 nanosheets were prepared through simple microwave-assisted method. The experimental results suggesting that the SiO2 shell layer between the fillers and polymer matrix could effectively improve the dielectric constant, dielectric loss, AC conductivity, and breakdown strength of composites films. The composite films load with 10 vol.% 2D Bi2Te3@SiO2 nanosheets exhibits a high dielectric constant of 70.3 at 1 kHz and relatively low dielectric loss of 0.058 at 1 kHz. The finite element simulation of electric field and electric current density distribution revealed that the SiO2 shell layer between the fillers and polymer matrix could effectively improve the energy loss, local electric field strength, and breakdown strength of composite films. Therefore, this work will provide a promising route to achieve high-performance capacitors.

Composite Films Formed by Cellulose nanocrystals and Latex Nanoparticles: Optical, Structural, and Mechanical Properties

NASA Astrophysics Data System (ADS)

Vollick, Brandon McRae

This thesis describes the preparation of iridescent, birefringent, composite films composed of cellulose nanocrystals (CNCs), latex nanoparticles (NPs) and a NP crosslinker; hexanediamine (HDA). First, aqueous suspensions were prepared with varying quantities of CNCs, NPs and HDA before equilibrating for one week. The cholesteric (Ch) phase was then cast and dried into a film. The optical, structural and mechanical properties of the film was analyzed. Second, films with identical compositions of CNCs, NPs, and HDA were fabricated in three different ways to yield films of different morphology, (i) fast drying of an isotropic suspension, yielding an isotropic film, (ii) slow drying of an isotropic suspension, yielding a partially Ch films, (iii) slow drying of an equilibrated suspension, yielding a highly Ch film. The optical and mechanical properties of the films was analyzed.

Effect of various SnO2 pH on ZnO/SnO2-composite film via immersion technique

NASA Astrophysics Data System (ADS)

Malek, M. F.; Mohamed, R.; Mamat, M. H.; Ismail, A. S.; Yusoff, M. M.; Rusop, M.

2018-05-01

ZnO/SnO2-composite film has been synthesized via immersion technique with various pH of SnO2. The pH of SnO2 were varied between 4.5 and 6.5. The optical measurements of the samples were carried out using Varian Cary 5000 UV-Vis spectrophotometer within the range from 350 nm to 800 nm at room temperature in air with a data interval of 1 nm. On the other hand, the optical photoluminescence properties were measured by a photoluminescence spectrometer (PL, model: Horiba Jobin Yvon - 79 DU420A-OE-325) using a He-Cd laser as the excitation source at 325 nm. These highly oriented ZnO/SnO2-composite film are potential for the creation of functional materials, such as the sensors, solar cells and etc.

The Effects of Oral Planning on Fifth-Grade Composition.

ERIC Educational Resources Information Center

Beeker, Ruth Ann

In this study, three grade 5 classes were tested during a 3 week period to determine the effect that classroom discussion has on certain quantitative aspects of composition. Each week, 78 subjects viewed a short film with no narration and--after either no discussion, class discussion, or paired-student discussion--were required to write…

Phonon scattering mechanisms dictating the thermal conductivity of lead zirconate titanate (PbZr 1- xTi xO 3) thin films across the compositional phase diagram

DOE PAGES

Foley, Brian M.; Paisley, Elizabeth A.; DiAntonio, Christopher; ...

2017-05-23

This paper represents a thorough investigation of the thermal conductivity (κ) in both thin film and bulk PbZr 1–xTi xO 3 (PZT) across the compositional phase diagram. Given the technological importance of PZT as a superb piezoelectric and ferroelectric material in devices and systems impacting a wide array of industries, this research serves to fill the gap in knowledge regarding the thermal properties. The thermal conductivities of both thin film and bulk PZT are found to vary by a considerable margin as a function of composition x. Additionally, we observe a discontinuity in κ in the vicinity of the morphotropicmore » phase boundary (MPB, x = 0.48) where there is a 20%–25% decrease in κ in our thin film data, similar to that found in literature data for bulk PZT. The comparison between bulk and thin film materials highlights the sensitivity of κ to size effects such as film thickness and grain size even in disordered alloy/solid-solution materials. A model for the thermal conductivity of PZT as a function of composition (κ(x)) is presented, which enables the application of the virtual crystal approximation for alloy-type material systems with very different crystals structures, resulting in differing temperature trends for κ. We show that in the case of crystalline solid-solutions where the thermal conductivity of one of the parent materials exhibits glass-like temperature trends the compositional dependence of thermal conductivity is relatively constant for most values of x. Finally, this is in stark contrast with the typical trends of thermal conductivity with x in alloys, where the thermal conductivity increases dramatically as the composition of the alloy or solid-solution approaches that of a pure parent materials (i.e., as x = 0 or 1).« less

Phonon scattering mechanisms dictating the thermal conductivity of lead zirconate titanate (PbZr 1- xTi xO 3) thin films across the compositional phase diagram

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foley, Brian M.; Paisley, Elizabeth A.; DiAntonio, Christopher

This paper represents a thorough investigation of the thermal conductivity (κ) in both thin film and bulk PbZr 1–xTi xO 3 (PZT) across the compositional phase diagram. Given the technological importance of PZT as a superb piezoelectric and ferroelectric material in devices and systems impacting a wide array of industries, this research serves to fill the gap in knowledge regarding the thermal properties. The thermal conductivities of both thin film and bulk PZT are found to vary by a considerable margin as a function of composition x. Additionally, we observe a discontinuity in κ in the vicinity of the morphotropicmore » phase boundary (MPB, x = 0.48) where there is a 20%–25% decrease in κ in our thin film data, similar to that found in literature data for bulk PZT. The comparison between bulk and thin film materials highlights the sensitivity of κ to size effects such as film thickness and grain size even in disordered alloy/solid-solution materials. A model for the thermal conductivity of PZT as a function of composition (κ(x)) is presented, which enables the application of the virtual crystal approximation for alloy-type material systems with very different crystals structures, resulting in differing temperature trends for κ. We show that in the case of crystalline solid-solutions where the thermal conductivity of one of the parent materials exhibits glass-like temperature trends the compositional dependence of thermal conductivity is relatively constant for most values of x. Finally, this is in stark contrast with the typical trends of thermal conductivity with x in alloys, where the thermal conductivity increases dramatically as the composition of the alloy or solid-solution approaches that of a pure parent materials (i.e., as x = 0 or 1).« less

Hierarchical porous graphene/polyaniline composite film with superior rate performance for flexible supercapacitors.

PubMed

Meng, Yuena; Wang, Kai; Zhang, Yajie; Wei, Zhixiang

2013-12-23

A highly flexible graphene free-standing film with hierarchical structure is prepared by a facile template method. With a porous structure, the film can be easily bent and cut, and forms a composite with another material as a scaffold. The 3D graphene film exhibits excellent rate capability and its capacitance is further improved by forming a composite with polyaniline nanowire arrays. The flexible hierarchical composite proves to be an excellent electrode material for flexible supercapacitors. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of ultrasonic treatment on amylose-lipid complex formation and properties of sweet potato starch-based films.

PubMed

Liu, Pengfei; Wang, Rui; Kang, Xuemin; Cui, Bo; Yu, Bin

2018-06-01

To investigate the effect of ultrasonic treatment on the properties of sweet potato starch and sweet potato starch-based films, the complexing index, thermograms and diffractograms of the sweet potato starch-lauric acid composite were tested, and light transmission, microstructure, and mechanical and moisture barrier properties of the films were measured. The results indicated that the low power density ultrasound was beneficial to the formation of an inclusion complex. In thermograms, the gelatinization enthalpies of the ultrasonically treated starches were lower than those of the untreated sample. With the ultrasonic amplitude increased from 40% to 70%, the melting enthalpy (ΔH) of the inclusion complex gradually decreased. X-ray diffraction revealed that the diffraction intensity of the untreated samples was weaker than that of the ultrasonically treated samples. When the ultrasonic amplitude was above 40%, the diffraction intensity and relative crystallinity of inclusion complex gradually decreased. The scanning electronic microscope showed that the surface of the composite films became smooth after being treated by ultrasonication. Ultrasonication led to a reduction in film surface roughness under atomic force microscopy analysis. The films with ultrasonic treatment exhibited higher light transmission, lower elongation at break, higher tensile strength and better moisture barrier property than those without ultrasonic treatment. Copyright © 2018 Elsevier B.V. All rights reserved.

High-performance flexible hydrogen sensor made of WS2 nanosheet-Pd nanoparticle composite film

NASA Astrophysics Data System (ADS)

Kuru, Cihan; Choi, Duyoung; Kargar, Alireza; Liu, Chin Hung; Yavuz, Serdar; Choi, Chulmin; Jin, Sungho; Bandaru, Prabhakar R.

2016-05-01

We report a flexible hydrogen sensor, composed of WS2 nanosheet-Pd nanoparticle composite film, fabricated on a flexible polyimide substrate. The sensor offers the advantages of light-weight, mechanical durability, room temperature operation, and high sensitivity. The WS2-Pd composite film exhibits sensitivity (R 1/R 2, the ratio of the initial resistance to final resistance of the sensor) of 7.8 to 50 000 ppm hydrogen. Moreover, the WS2-Pd composite film distinctly outperforms the graphene-Pd composite, whose sensitivity is only 1.14. Furthermore, the ease of fabrication holds great potential for scalable and low-cost manufacturing of hydrogen sensors.

Magnetoelectric coupling in oxygen deficient La0.67Sr0.33MnO3-δ/BaTiO3 composite film

NASA Astrophysics Data System (ADS)

Wang, Jianyuan; Han, Zhuokun; Bai, Jianying; Luo, Bingcheng; Chen, Changle

2018-04-01

The effect of magnetic field on the polarization and dielectric properties in oxygen deficient La0.67Sr0.33MnO3-δ/BaTiO3 composite film are investigated. A temperature dependent polarization variation induced by the magnetic field is observed. Under a magnetic fields of 0.8 T, the enhancement of saturation polarization is remarkable at low temperature region with a maximum changing rate 66.5% occurring at 70 K, whereas it is indistinctive at high temperature. The composite film also exhibits significant magnetodielectric property. The positive changing rate of dielectric constant ηε induced by 0.8 T magnetic field reaches the maximum of 80% and 57% at 80 K with the frequency of 1 kHz and 100 kHz, respectively, and the corresponding changing rate of dielectric loss get the negative peak of -27% and -22%. The magneto-induced polarization and dielectric change may result from the charge-based coupling as well as the Maxwell-Wagner effect in this heterojunction.

Technical feasibility and economical viability of remote hybrid power systems in Northern Ontario

NASA Astrophysics Data System (ADS)

Gubbels, Jason Matthew

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Evaluation of remotely sensed wetland mapping

NASA Astrophysics Data System (ADS)

Gluck, Michael J.

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Tectonic magnetic fabrics in pure and simple shear: Experimental investigations

NASA Astrophysics Data System (ADS)

Alford, Craig Steven

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Use of a single epiphyte lichen species Hypogymnia physodes as an indicator of air quality in northern Ontario

NASA Astrophysics Data System (ADS)

Pfeiffer, Helmut Nickolaus

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Gravity study of an Archaen crustal segment near Thunder Bay, Ontario

NASA Astrophysics Data System (ADS)

Cheadle, Scott Philip

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Northern lights: A history of Thunder Bay Hydro

NASA Astrophysics Data System (ADS)

Black, David Leo

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Static dielectric properties of an ensemble of restricted one-dimensional oscillators

NASA Astrophysics Data System (ADS)

Tjipto Margo, Broto

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Photoluminescence and Raman characterization of PLEE and MBE grown semiconductor epilayers

NASA Astrophysics Data System (ADS)

Harrison, Dale A.

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Development of nonlinear 3-D, and novel 2-D optical microscope imaging systems for time-lapse imaging

NASA Astrophysics Data System (ADS)

Girardin, Robert Joseph

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Simple route to new palladium-carbonyl-bis(diphenylphosphino)methane complexes

NASA Astrophysics Data System (ADS)

Krysa, Elizabeth

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Impurity band conduction in reduced samples of bismuth iron molybdate

NASA Astrophysics Data System (ADS)

McIntyre, Shawn M.

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Photon number density operator

NASA Astrophysics Data System (ADS)

Melde, Thomas

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Dielectric and infrared studies of radio frequency processes in some alcohols

NASA Astrophysics Data System (ADS)

Mandal, Humayun

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Real-time implementation of some attitude estimation algorithms on a quadrotor UAV

NASA Astrophysics Data System (ADS)

Nayak, Siddhant

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Ordered supramolecular oligothiophene structures on passivated silicon surfaces

NASA Astrophysics Data System (ADS)

Liu, Renjie

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Synthesis and electrochemical study of PtIr and PtRu nanomaterials

NASA Astrophysics Data System (ADS)

Alammari, Walaa S.

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

P-type gallium nitride semiconductor development and characterization for LEDs and other devices

NASA Astrophysics Data System (ADS)

Togtema, Gregorey L.

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Diamond Composite Films for Protective Coatings on Metals and Method of Formation

NASA Technical Reports Server (NTRS)

Ong, Tiong P. (Inventor); Shing, Yuh-Han (Inventor)

1997-01-01

Composite films consisting of diamond crystallites and hard amorphous films such as diamond-like carbon, titanium nitride, and titanium oxide are provided as protective coatings for metal substrates against extremely harsh environments. A composite layer having diamond crystallites and a hard amorphous film is affixed to a metal substrate via an interlayer including a bottom metal silicide film and a top silicon carbide film. The interlayer is formed either by depositing metal silicide and silicon carbide directly onto the metal substrate, or by first depositing an amorphous silicon film, then allowing top and bottom portions of the amorphous silicon to react during deposition of the diamond crystallites, to yield the desired interlayer structure.

Antimicrobial activity of biopolymer-antibiotic thin films fabricated by advanced pulsed laser methods

NASA Astrophysics Data System (ADS)

Cristescu, R.; Popescu, C.; Dorcioman, G.; Miroiu, F. M.; Socol, G.; Mihailescu, I. N.; Gittard, S. D.; Miller, P. R.; Narayan, R. J.; Enculescu, M.; Chrisey, D. B.

2013-08-01

We report on thin film deposition by matrix assisted pulsed laser evaporation (MAPLE) of two polymer-drug composite thin film systems. A pulsed KrF* excimer laser source (λ = 248 nm, τ = 25 ns, ν = 10 Hz) was used to deposit composite thin films of poly(D,L-lactide) (PDLLA) containing several gentamicin concentrations. FTIR spectroscopy was used to demonstrate that MAPLE-transferred materials exhibited chemical structures similar to those of drop cast materials. Scanning electron microscopy data indicated that MAPLE may be used to fabricate thin films of good morphological quality. The activity of PDLLA-gentamicin composite thin films against Staphylococcus aureus bacteria was demonstrated using drop testing. The influence of drug concentration on microbial viability was also assessed. Our studies indicate that polymer-drug composite thin films prepared by MAPLE may be used to impart antimicrobial activity to implants, medical devices, and other contact surfaces.

AES study on the chemical composition of ferroelectric BaTiO3 thin films RF sputter-deposited on silicon

NASA Technical Reports Server (NTRS)

Dharmadhikari, V. S.; Grannemann, W. W.

1983-01-01

AES depth profiling data are presented for thin films of BaTiO3 deposited on silicon by RF sputtering. By profiling the sputtered BaTiO3/silicon structures, it was possible to study the chemical composition and the interface characteristics of thin films deposited on silicon at different substrate temperatures. All the films showed that external surface layers were present, up to a few tens of angstroms thick, the chemical composition of which differed from that of the main layer. The main layer had stable composition, whereas the intermediate film-substrate interface consisted of reduced TiO(2-x) oxides. The thickness of this intermediate layer was a function of substrate temperature. All the films showed an excess of barium at the interface. These results are important in the context of ferroelectric phenomena observed in BaTiO3 thin films.

Spatially resolved variations in reflectivity across iron oxide thin films

NASA Astrophysics Data System (ADS)

Kelley, Chris S.; Thompson, Sarah M.; Gilks, Daniel; Sizeland, James; Lari, Leonardo; Lazarov, Vlado K.; Matsuzaki, Kosuke; LeFrançois, Stéphane; Cinque, Gianfelice; Dumas, Paul

2017-11-01

The spin polarising properties of the iron oxide magnetite (Fe3O4) make it attractive for use in spintronic devices, but its sensitivity to compositional and structural variations make it challenging to prepare reliably. Infrared microspectroscopy and modelling are used to determine the spatial variation in the chemical composition of three thin films of iron oxide; one prepared by pulsed laser deposition (PLD), one by molecular beam epitaxy (MBE) deposition of iron whilst simultaneously flowing oxygen into the chamber and one by flowing oxygen only once deposition is complete. The technique is easily able to distinguish between films which contain metallic iron and different iron oxide phases as well as spatial variations in composition across the films. The film grown by post-oxidising iron is spatially uniform but not fully oxidised, the film grown by simultaneously oxidising iron showed spatial variation in oxide composition while the film grown by PLD was spatially uniform magnetite.

Surface-coated fly ash reinforced biodegradable poly(vinyl alcohol) composite films: part 2-analysis and characterization

NASA Astrophysics Data System (ADS)

Nath, D. C. D.; Bandyopadhyay, S.; Campbell, J.; Yu, A.; Blackburn, D.; White, C.

2010-12-01

Composite films of poly(vinyl alcohol) (PVA) reinforced with 5, 10, 15, 20 and 25 wt.% surface-coated fly ash by surfactant, sodium lauryl sulphate (SLS-FA) along with 1 wt.% cross-linking agent, glutaraldehyde (GLA) were prepared by aqueous casting method. The tensile strengths of the composite films were increased proportionally with the addition of SLS-FA. The maximum 75% higher strength of the composite with 20 wt.% was achieved compared to that of neat PVA. The modulus of the composites was also increased proportionally with SLS-FA and the maximum 218% reached in composite with 20 wt.%, but the strain at break was decreased with addition of SLS-FA. Changes in FTIR spectra reflect the chemical and/or physical bonding in the ternary PVA, SLS-FA and GLA component systems. In the study of surface morphology, the connectivity was visualized in SEM images along with interstitial voids. The films with SLS-FA show 53% smoother surface calculated with AFM compared to unmodified FA composite films.

Influence of calcinated and non calcinated nanobioglass particles on hardness and bioactivity of sol-gel-derived TiO2-SiO2 nano composite coatings on stainless steel substrates.

PubMed

Dadash, Mohammad Saleh; Karbasi, Saeed; Esfahani, Mojtaba Nasr; Ebrahimi, Mohammad Reza; Vali, Hojatollah

2011-04-01

Thick films of calcinated and non calcinated nanobioglass (NBG)-titania composite coatings were prepared on stainless steel substrates by alkoxide sol-gel process. Dip-coating method was used for the films preparation. The morphology, structure and composition of the nano composite films were evaluated using environmental scanning electron microscope, X-ray diffraction and Fourier transform infrared spectroscope. The SEM investigation results showed that prepared thick NBG-titania films are smooth and free of macrocracking, fracture or flaking. The grain size of these films was uniform and nano scale (50-60 nm) which confirmed with TEM. Also FTIR confirmed the presence of Si-O-Si bands on the calcinated NBG-titania films. The hardness of the prepared films (TiO(2)-calcinated NBG and TiO(2)-Non calcinated NBG) was compared by using micro hardness test method. The results verified that the presence of calcinated NBG particles in NBG-titania composite enhanced gradually the mechanical data of the prepared films. The in vitro bioactivity of these films was discussed based on the analysis of the variations of Ca and P concentrations in the simulated body fluid (SBF) and their surface morphologies against immersion time. Surface morphology and Si-O-Si bands were found to be of great importance with respect to the bioactivity of the studied films. The results showed that calcinated NBG-titania films have better bioactivity than non calcinated NBG-titania films.

Characterization of Antimicrobial Poly (Lactic Acid)/Nano-Composite Films with Silver and Zinc Oxide Nanoparticles

PubMed Central

Chu, Zhuangzhuang; Zhao, Tianrui; Li, Lin; Fan, Jian; Qin, Yuyue

2017-01-01

Antimicrobial active films based on poly (lactic acid) (PLA) were prepared with nano-silver (nano-Ag) and nano-zinc oxide (nano-ZnO) using a solvent volatilizing method. The films were characterized for mechanical, structural, thermal, physical and antimicrobial properties. Scanning electron microscopy (SEM) images characterized the fracture morphology of the films with different contents of nano-Ag and nano-ZnO. The addition of nanoparticles into the pure PLA film decreased the tensile strength and elasticity modulus and increased the elongation of breaks—in other words, the flexibility and extensibility of these composites improved. According to the results of differential scanning calorimetry (DSC), the glass transition temperature of the PLA nano-composite films decreased, and the crystallinity of these films increased; a similar result was apparent from X-ray diffraction (XRD) analysis. The water vapor permeability (WVP) and opacity of the PLA nano-composite films augmented compared with pure PLA film. Incorporation of nanoparticles to the PLA films significantly improved the antimicrobial activity to inhibit the growth of Escherichia coli. The results indicated that PLA films with nanoparticles could be considered a potential environmental-friendly packaging material. PMID:28773018

Assembly of 1D nanofibers into a 2D bi-layered composite nanofibrous film with different functionalities at the two layers via layer-by-layer electrospinning.

PubMed

Wang, Zijiao; Ma, Qianli; Dong, Xiangting; Li, Dan; Xi, Xue; Yu, Wensheng; Wang, Jinxian; Liu, Guixia

2016-12-21

A two-dimensional (2D) bi-layered composite nanofibrous film assembled by one-dimensional (1D) nanofibers with trifunctionality of electrical conduction, magnetism and photoluminescence has been successfully fabricated by layer-by-layer electrospinning. The composite film consists of a polyaniline (PANI)/Fe 3 O 4 nanoparticle (NP)/polyacrylonitrile (PAN) tuned electrical-magnetic bifunctional layer on one side and a Tb(TTA) 3 (TPPO) 2 /polyvinylpyrrolidone (PVP) photoluminescent layer on the other side, and the two layers are tightly combined face-to-face together into the novel bi-layered composite film of trifunctionality. The brand-new film has totally different characteristics at the double layers. The electrical conductivity and magnetism of the electrical-magnetic bifunctional layer can be, respectively, tunable via modulating the PANI and Fe 3 O 4 NP contents, and the highest electrical conductivity can reach up to the order of 10 -2 S cm -1 , and predominant intense green emission at 545 nm is obviously observed in the photoluminescent layer under the excitation of 357 nm single-wavelength ultraviolet light. More importantly, the luminescence intensity of the photoluminescent layer remains almost unaffected by the electrical-magnetic bifunctional layer because the photoluminescent materials have been successfully isolated from dark-colored PANI and Fe 3 O 4 NPs. By comparing with the counterpart single-layered composite nanofibrous film, it is found that the bi-layered composite nanofibrous film has better performance. The novel bi-layered composite nanofibrous film with trifunctionality has potential in the fields of nanodevices, molecular electronics and biomedicine. Furthermore, the design conception and fabrication technique for the bi-layered multifunctional film provide a new and facile strategy towards other films of multifunctionality.

Epitaxial growth and physical properties of ternary nitride thin films by polymer-assisted deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Enriquez, Erik M.; Zhang, Yingying; Chen, Aiping

2016-08-26

Epitaxial layered ternary metal-nitride FeMoN 2, (Fe 0.33 Mo 0.67)MoN 2, CoMoN 2, and FeWN 2 thin films have been grown on c-plane sapphire substrates by polymer-assisted deposition. The ABN 2 layer sits on top of the oxygen sublattices of the substrate with three possible matching configurations due to the significantly reduced lattice mismatch. The doping composition and elements affect not only the out-of-plane lattice parameters but also the temperature-dependent electrical properties. These films have resistivity in the range of 0.1–1 mΩ·cm, showing tunable metallic or semiconducting behaviors by adjusting the composition. A modified parallel connection channel model has beenmore » used to analyze the grain boundary and Coulomb blockade effect on the electrical properties. Furthermore, the growth of the high crystallinity layered epitaxial thin films provides an avenue to study the composition-structure-property relationship in ABN 2 materials through A and B-site substitution.« less

Study of optical properties of vacuum evaporated carbon nanotube containing Se80Te16Cu4 thin films

NASA Astrophysics Data System (ADS)

Upadhyay, A. N.; Tiwari, R. S.; Singh, Kedar

2016-08-01

Thin films of Se80Te16Cu4 glassy alloy and 3 wt.% of carbon nanotubes (CNTs) containing Se80Te16Cu4 glassy composite were deposited on clean glass substrate by thermal evaporation technique. The scanning electron microscope and energy dispersive x-ray analysis were performed to investigate the surface morphology and elemental composition of as synthesised samples. The reflectance and transmittance spectra of as-deposited thin films were recorded (200-1100 nm) by using UV/VIS/NIR spectrophotometer. The optical band gap and optical constants such as absorption coefficient (α), refractive index (n) and extinction coefficient (k) of Se80Te16Cu4 and 3 wt.% CNTs-Se80Te16Cu4 glassy composite thin films were calculated. It is observed that optical properties alter due to CNTs incorporation in Se80Te16Cu4 glassy alloy. Effect on optical properties due to CNTs incorporation can be explained in terms of concentration of unsaturated bonds/defects in the localised states.

Adhesive flexible barrier film, method of forming same, and organic electronic device including same

DOEpatents

Blizzard, John Donald; Weidner, William Kenneth

2013-02-05

An adhesive flexible barrier film comprises a substrate and a barrier layer disposed on the substrate. The barrier layer is formed from a barrier composition comprising an organosilicon compound. The adhesive flexible barrier film also comprises an adhesive layer disposed on the barrier layer and formed from an adhesive composition. A method of forming the adhesive flexible barrier film comprises the steps of disposing the barrier composition on the substrate to form the barrier layer, disposing the adhesive composition on the barrier layer to form the adhesive layer, and curing the barrier layer and the adhesive layer. The adhesive flexible barrier film may be utilized in organic electronic devices.

Electroactive Film of Myoglobin Incorporated in a 3D-porous Calcium Alginate Film with Polyvinyl Alcohol, Glycerin and Gelatin.

PubMed

Zheng, Xueqin; Sun, Hong; Hou, Shifeng

2015-01-01

In this work, an electroactive porous Mb-CA's composite film was fabricated by incorporating myoglobin (Mb) in a three-dimension (3D) porous calcium alginate (CA) film with polyvinyl alcohol, glycerol, and gelatin. The porous Mb-CA's film modified electrodes exhibited a pair of well-defined, quasi-reversible cyclic voltammetric (CV) peaks at about -0.37 V vs. SCE in pH 7.0 buffers, characteristic of Mb heme Fe((III))/Fe((II)) redox couples. The electrochemical parameters, such as formal potentials (E(o')) and apparent heterogeneous electron-transfer rate constants (ks), were estimated by square-wave voltammetry with nonlinear regression analysis. The porous CA's composite film could form hydrogel in aqueous solution. The positions of the Soret absorbance band suggest that Mb in the CA's composite film kept its native states in the medium pH range. Hydrogen peroxide, oxygen, and nitrite were electrochemically catalyzed by the Mb-CA's composite film with significant lowering of the reduction overpotential.

Tungsten-rhenium thin film thermocouples for SiC-based ceramic matrix composites

NASA Astrophysics Data System (ADS)

Tian, Bian; Zhang, Zhongkai; Shi, Peng; Zheng, Chen; Yu, Qiuyue; Jing, Weixuan; Jiang, Zhuangde

2017-01-01

A tungsten-rhenium thin film thermocouple is designed and fabricated, depending on the principle of thermal-electric effect caused by the high temperature. The characteristics of thin film thermocouples in different temperatures are investigated via numerical analysis and analog simulation. The working mechanism and thermo-electric features of the thermocouples are analyzed depending on the simulation results. Then the thin film thermocouples are fabricated and calibrated. The calibration results show that the thin film thermocouples based on the tungsten-rhenium material achieve ideal static characteristics and work well in the practical applications.

Does Translational Symmetry Matter on the Micro Scale? Fibroblastic and Osteoblastic Interactions with the Topographically Distinct Poly(ε-caprolactone)/Hydroxyapatite Thin Films

PubMed Central

2015-01-01

Material composition and topography of the cell-contacting material interface are important considerations in the design of biomaterials at the nano and micro scales. This study is one of the first to have assessed the osteoblastic response to micropatterned polymer–ceramic composite surfaces. In particular, the effect of topographic variations of composite poly(ε-caprolactone)/hydroxyapatite (PCL/HAp) films on viability, proliferation, migration and osteogenesis of fibroblastic and osteoblastic MC3T3-E1 cells was evaluated. To that end, three different micropatterned PCL/HAp films were compared: flat and textured, the latter of which included films comprising periodically arranged and randomly distributed oval topographic features 10 μm in diameter, 20 μm in separation and 10 μm in height, comparable to the dimensions of MC3T3-E1 cells. PCL/HAp films were fabricated by the combination of a bottom-up, soft chemical synthesis of the ceramic, nanoparticulate phase and a top-down, photolithographic technique for imprinting fine, microscale features on them. X-ray diffraction analysis indicated an isotropic orientation of both the polymeric chains and HAp crystallites in the composite samples. Biocompatibility tests indicated no significant decrease in their viability when grown on PCL/HAp films. Fibroblast proliferation and migration onto PCL/HAp films proceeded slower than on the control borosilicate glass, with the flat composite film fostering more cell migration activity than the films containing topographic features. The gene expression of seven analyzed osteogenic markers, including procollagen type I, osteocalcin, osteopontin, alkaline phosphatase, and the transcription factors Runx2 and TGFβ-1, was, however, consistently upregulated in cells grown on PCL/HAp films comprising periodically ordered topographic features, suggesting that the higher levels of symmetry of the topographic ordering impose a moderate mechanochemical stress on the adherent cells and thus promote a more favorable osteogenic response. The obtained results suggest that topography can be a more important determinant of the cell/surface interaction than the surface chemistry and/or stiffness as well as that the regularity of the distribution of topographic features can be a more important variable than the topographic features per se. PMID:25014232

Effect of cadmium incorporation on the properties of zinc oxide thin films

NASA Astrophysics Data System (ADS)

Bharath, S. P.; Bangera, Kasturi V.; Shivakumar, G. K.

2018-02-01

Cd x Zn1- x O (0 ≤ x ≤ 0.20) thin films are deposited on soda lime glass substrates using spray pyrolysis technique. To check the thermal stability, Cd x Zn1- x O thin films are subjected to annealing. Both the as-deposited and annealed Cd x Zn1- x O thin films are characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive X-ray analysis (EDAX) to check the structural, surface morphological and compositional properties, respectively. XRD analysis reveals that the both as-deposited and annealed Cd x Zn1- x O thin films are (002) oriented with wurtzite structure. SEM studies confirm that as-deposited, as well as annealed Cd x Zn1- x O thin films are free from pinholes and cracks. Compositional analysis shows the deficiency in Cd content after annealing. Optical properties evaluated from UV-Vis spectroscopy shows red shift in the band gap for Cd x Zn1- x O thin films. Electrical property measured using two probe method shows a decrease in the resistance after Cd incorporation. The results indicate that cadmium can be successfully incorporated in zinc oxide thin films to achieve structural changes in the properties of films.

Uniformly-dispersed nanohydroxapatite-reinforced poly(ε-caprolactone) composite films for tendon tissue engineering application.

PubMed

Tong, Shi Yun; Wang, Zuyong; Lim, Poon Nian; Wang, Wilson; Thian, Eng San

2017-01-01

Regeneration of injuries at tendon-to-bone interface (TBI) remains a challenging issue due to the complex tissue composition involving both soft tendon tissues and relatively hard bone tissues. Tissue engineering using polymeric/ceramic composites has been of great interest to generate scaffolds for tissue's healing at TBI. Herein, we presented a novel method to blend polymers and bioceramics for tendon tissue engineering application. A homogeneous composite comprising of nanohydroxyapatite (nHA) particles in poly(ε-caprolactone) (PCL) matrix was obtained using a combination of solvent and mechanical blending process. X-ray diffraction analysis showed that the as-fabricated PCL/nHA composite film retained phase-pure apatite and semi-crystalline properties of PCL. Infrared spectroscopy spectra confirmed that the PCL/nHA composite film exhibited the characteristics functional groups of PCL and nHA, without alteration to the chemical properties of the composite. The incorporation of nHA resulted in PCL/nHA composite film with improved mechanical properties such as Young's Modulus and ultimate tensile stress, which were comparable to that of the native human rotator tendon. Seeding with human tenocytes, cells attached on the PCL/nHA composite film, and after 14days of culturing, these cells could acquire elongated morphology without induced cytotoxicity. PCL/nHA composite film could also result in increased cell metabolism with prolonged culturing, which was comparable to that of the PCL group and higher than that of the nHA group. All these results demonstrated that the developed technique of combining solvent and mechanical blending could be applied to fabricate composite films with potential for tendon tissue engineering applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis and characterization of cobalt doped nickel oxide thin films by spray pyrolysis method

NASA Astrophysics Data System (ADS)

Sathisha, D.; Naik, K. Gopalakrishna

2018-05-01

Cobalt (Co) doped nickel oxide (NiO) thin films were deposited on glass substrates at a temperature of about 400 °C by spray pyrolysis method. The effect of Co doping concentration on structural, optical and compositional properties of NiO thin films was investigated. X-ray diffraction result shows that the deposited thin films are polycrystalline in nature. Surface morphologies of the deposited thin films were observed by FESEM and AFM. EDS spectra showed the incorporation of Co dopants in NiO thin films. Optical properties of the grown thin films were characterized by UV-visible spectroscopy. It was found that the optical band gap energy and transmittance of the films decrease with increasing Co doping concentration.

Influence of Interleaved Films on the Mechanical Properties of Carbon Fiber Fabric/Polypropylene Thermoplastic Composites

PubMed Central

Kim, Jong Won; Lee, Joon Seok

2016-01-01

A laminated composite was produced using a thermoplastic prepreg by inserting an interleaved film with the same type of matrix as the prepreg during the lay-up process to improve the low interlaminar properties, which is a known weakness of laminated composites. Carbon fiber fabric (CFF) and polypropylene (PP) were used to manufacture the thermoplastic prepregs. Eight prepregs were used to produce the laminated composites. Interleaved films with different thicknesses were inserted into each prepreg. The physical properties of the composite, such as thickness, density, fiber volume fraction (Vf), and void content (Vc), were examined. The tensile strength, flexural strength, interlaminar shear strength (ILSS), impact property, and scanning electron microscopy (SEM) were used to characterize the mechanical properties. Compared to the composite without any inserted interleaved film, as the thickness of the inserted interleaved resin film was increased, Vc decreased by 51.45%. At the same time, however, the tensile strength decreased by 8.75%. Flexural strength increased by 3.79% and flexural modulus decreased by 15.02%. Interlaminar shear strength increased by 11.05% and impact strength increased by 15.38%. Fracture toughness of the laminated composite was improved due to insertion of interleaved film. PMID:28773467

Influence of Interleaved Films on the Mechanical Properties of Carbon Fiber Fabric/Polypropylene Thermoplastic Composites.

PubMed

Kim, Jong Won; Lee, Joon Seok

2016-05-06

A laminated composite was produced using a thermoplastic prepreg by inserting an interleaved film with the same type of matrix as the prepreg during the lay-up process to improve the low interlaminar properties, which is a known weakness of laminated composites. Carbon fiber fabric (CFF) and polypropylene (PP) were used to manufacture the thermoplastic prepregs. Eight prepregs were used to produce the laminated composites. Interleaved films with different thicknesses were inserted into each prepreg. The physical properties of the composite, such as thickness, density, fiber volume fraction ( V f ), and void content ( V c ), were examined. The tensile strength, flexural strength, interlaminar shear strength (ILSS), impact property, and scanning electron microscopy (SEM) were used to characterize the mechanical properties. Compared to the composite without any inserted interleaved film, as the thickness of the inserted interleaved resin film was increased, V c decreased by 51.45%. At the same time, however, the tensile strength decreased by 8.75%. Flexural strength increased by 3.79% and flexural modulus decreased by 15.02%. Interlaminar shear strength increased by 11.05% and impact strength increased by 15.38%. Fracture toughness of the laminated composite was improved due to insertion of interleaved film.

Organometallic Polymeric Conductors

NASA Technical Reports Server (NTRS)

Youngs, Wiley J.

1997-01-01

For aerospace applications, the use of polymers can result in tremendous weight savings over metals. Suitable polymeric materials for some applications like EMI shielding, spacecraft grounding, and charge dissipation must combine high electrical conductivity with long-term environmental stability, good processability, and good mechanical properties. Recently, other investigators have reported hybrid films made from an electrically conductive polymer combined with insulating polymers. In all of these instances, the films were prepared by infiltrating an insulating polymer with a precursor for a conductive polymer (either polypyrrole or polythiophene), and oxidatively polymerizing the precursor in situ. The resulting composite films have good electrical conductivity, while overcoming the brittleness inherent in most conductive polymers. Many aerospace applications require a combination of properties. Thus, hybrid films made from polyimides or other engineering resins are of primary interest, but only if conductivities on the same order as those obtained with a polystyrene base could be obtained. Hence, a series of experiments was performed to optimize the conductivity of polyimide-based composite films. The polyimide base chosen for this study was Kapton. 3-MethylThiophene (3MT) was used for the conductive phase. Three processing variables were identified for producing these composite films, namely time, temperature, and oxidant concentration for the in situ oxidation. Statistically designed experiments were used to examine the effects of these variables and synergistic/interactive effects among variables on the electrical conductivity and mechanical strength of the films. Multiple linear regression analysis of the tensile data revealed that temperature and time have the greatest effect on maximum stress. The response surface of maximum stress vs. temperature and time (for oxidant concentration at 1.2 M) is shown. Conductivity of the composite films was measured for over 150 days in air at ambient temperature. The conductivity of the films dropped only half an order of magnitude in that time. Films aged under vacuum at ambient temperature diminished slightly in conductivity in the first day, but did not change thereafter. An experimental design approach will be applied to maximize the efficiency of the laboratory effort. The material properties (initial and long term) will also be monitored and assessed. The experimental results will add to the existing database for electrically conductive polymer materials. Attachments: 1) Synthesis Crystal Structure, and Polymerization of 1,2:5,6:9,10-Tribenzo-3,7,11,13-tetradehydro(14) annulene. 2) Reinvestigation of the Photocyclization of 1,4-Phenylene Bis(phenylmaleic anhydride): Preparation and Structure of (5)Helicene 5,6:9,10-Dianhydride. 3) Preparation and Structure Charecterization of a Platinum Catecholate Complex Containing Two 3-Ethynyltheophone Groups. and 4) Rigid-Rod Polymers Based on Noncoplanar 4,4'-Biphenyldiamines: A Review of Polymer Properties vs Configuration of Diamines.

Modeling and analysis of film composition on mechanical properties of maize starch based edible films.

PubMed

Prakash Maran, J; Sivakumar, V; Thirugnanasambandham, K; Kandasamy, S

2013-11-01

The present study investigates the influence of composition (content of maize starch (1-3 g), sorbitol (0.5-1.0 ml), agar (0.5-1.0 g) and tween-80 (0.1-0.5 ml)) on the mechanical properties (tensile strength, elongation, Young's modulus, puncture force and puncture deformation) of the maize starch based edible films using four factors with three level Box-Behnken design. The edible films were obtained by casting method. The results showed that, tween-80 increases the permeation of sorbitol in to the polymer matrix. Increasing concentration of sorbitol (hydrophilic nature and plasticizing effect of sorbitol) decreases the tensile strength, Young's modulus and puncture force of the films. The results were analyzed by Pareto analysis of variance (ANOVA) and second order polynomial models were obtained for all responses with high R(2) values (R(2)>0.95). 3D response surface plots were constructed to study the relationship between process variables and the responses. Copyright © 2013 Elsevier B.V. All rights reserved.

Elaboration of m-cresol polyamide12/ polyaniline composite films for antistatic applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mezdour, D.; Tabellout, M.; Bardeau, J.-F

2013-12-16

The present work deals with the preparation of transparent antistatic films from an extreme dilution of an intrinsically conducting polymer (ICP) with not coloured polymers. Our approach is based on the chemical polymerization of a very thin layer of Polyaniline (PANI) around particles of an insulating polymer (PA12). Films were obtained by dissolving the synthesized core-shell particles in m-Cresol. The electric property and structure relationships were investigated by using dielectric relaxation spectroscopy, X-ray diffraction and micro-Raman spectroscopy. Composite films exhibited a well established dc conductivity over all the frequency range for 10 wt. % of PANI concentration related to themore » conductive properties of the PANI clusters. X-ray diffraction data show broader and lower intensity of PA12 peaks when increasing PANI content, probably due to the additional doping effect of m- cresol. The doping of PA12/PANI films with Dodecyl benzene sulfonic acid (DBSA) was unequivocally verified by Raman spectroscopy.« less

Conductive polymer/fullerene blend thin films with honeycomb framework for transparent photovoltaic application

DOEpatents

Cotlet, Mircea; Wang, Hsing-Lin; Tsai, Hsinhan; Xu, Zhihua

2015-04-21

Optoelectronic devices and thin-film semiconductor compositions and methods for making same are disclosed. The methods provide for the synthesis of the disclosed composition. The thin-film semiconductor compositions disclosed herein have a unique configuration that exhibits efficient photo-induced charge transfer and high transparency to visible light.

Diatomite as a novel composite ingredient for chitosan film with enhanced physicochemical properties.

PubMed

Akyuz, Lalehan; Kaya, Murat; Koc, Behlul; Mujtaba, Muhammad; Ilk, Sedef; Labidi, Jalel; Salaberria, Asier M; Cakmak, Yavuz Selim; Yildiz, Aysegul

2017-12-01

Practical applications of biopolymers in different industries are gaining considerable increase day by day. But still, these biopolymers lack important properties in order to meet the industrial demands. In the same regard, in the current study, chitosan composite films are produced by incorporating diatomite soil at two different concentrations. In order to obtain a homogeneous film, glutaraldehyde was supplemented to chitosan solution as a cross-linker. Compositing diatomaceous earth to chitosan film resulted in improvement of various important physicochemical properties compared to control such as; enhanced film wettability, increase elongation at break and improved thermal stability (264-277°C). The microstructure of the film was observed to haveconsisted of homogeneously distributed blister-shaped structures arised due to the incorporation of diatomite. The incorporation of diatomite did not influence the overall antioxidant activity of the composite films, which can be ascribe to the difficulty radicals formation. Chitosan film incorporated with increasing fraction of diatomite revealed a notable enhancement in the antimicrobial activity. Additionally with the present study, for the first time possible interactions between chitosan/diatomite were determined via quantum chemical calculations. Current study will be helpful in giving a new biotechnological perspective to diatom in terms of its successful application in hydrophobic composite film production. Copyright © 2017 Elsevier B.V. All rights reserved.

Physical and mechanical properties of gelatin-CMC composite films under the influence of electrostatic interactions.

PubMed

Esteghlal, Sara; Niakousari, Mehrdad; Hosseini, Seyed Mohammad Hashem

2018-07-15

The objective of current study was to examine the electrostatic interactions between gelatin and carboxymethyl cellulose (CMC) as a function of pH and mixing ratio (MR) and to observe how the physical and mechanical properties of gelatin-CMC composite films are affected by these interactions. The interaction between biopolymers was studied using turbidometric analysis at different gelatin: CMC MRs and pH values. A reduction in pH and MR enhanced the electrostatic interactions; while, decreased the relative viscosity of mixed system. Physical and mechanical properties of resultant composite films were examined and compared with those of control gelatin films. Changes in the intensity of interactions between the two biopolymers resulted in films with different properties. Polymer complexation led to formation of resistant film networks of less solubility and swellability. Water vapor permeability (WVP) was not significantly (P≤0.05) influenced by incorporating CMC into continuous gelatin films. Composite films prepared at MR of 9:1 and pH opt (corresponding to the maximum amount of interaction) revealed different characteristics such as maximum amounts of WVP and swelling and minimum amounts of tensile strength and solubility. FTIR spectra of composite films confirmed that gelatin and CMC were not covalently bonded. Copyright © 2018 Elsevier B.V. All rights reserved.

Methods of making copper selenium precursor compositions with a targeted copper selenide content and precursor compositions and thin films resulting therefrom

DOEpatents

Curtis, Calvin J [Lakewood, CO; Miedaner, Alexander [Boulder, CO; van Hest, Marinus Franciscus Antonius Maria; Ginley, David S [Evergreen, CO; Leisch, Jennifer [Denver, CO; Taylor, Matthew [West Simsbury, CT; Stanbery, Billy J [Austin, TX

2011-09-20

Precursor compositions containing copper and selenium suitable for deposition on a substrate to form thin films suitable for semi-conductor applications. Methods of forming the precursor compositions using primary amine solvents and methods of forming the thin films wherein the selection of temperature and duration of heating controls the formation of a targeted species of copper selenide.

Biosensors Based on Ultrathin Film Composite Membranes

DTIC Science & Technology

1994-01-25

composite membranes should have a number C •’ of potential advantages including fast response time, simplicity of construction, and applicability to a number...The support membrane for the ultrathin film composite was an Anopore ( Alltech Associates) microporous alumina filter, these membranes are 55 Pm thick...constant 02 concentration in this solution. Finally, one of the most important potential advantage of a sensor based on an ultrathin film composite

Properties and Applications of High Emissivity Composite Films Based on Far-Infrared Ceramic Powder

PubMed Central

Xiong, Yabo; Huang, Shaoyun; Wang, Wenqi; Liu, Xinghai; Li, Houbin

2017-01-01

Polymer matrix composite materials that can emit radiation in the far-infrared region of the spectrum are receiving increasing attention due to their ability to significantly influence biological processes. This study reports on the far-infrared emissivity property of composite films based on far-infrared ceramic powder. X-ray fluorescence spectrometry, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray powder diffractometry were used to evaluate the physical properties of the ceramic powder. The ceramic powder was found to be rich in aluminum oxide, titanium oxide, and silicon oxide, which demonstrate high far-infrared emissivity. In addition, the micromorphology, mechanical performance, dynamic mechanical properties, and far-infrared emissivity of the composite were analyzed to evaluate their suitability for strawberry storage. The mechanical properties of the far-infrared radiation ceramic (cFIR) composite films were not significantly influenced (p ≥ 0.05) by the addition of the ceramic powder. However, the dynamic mechanical analysis (DMA) properties of the cFIR composite films, including a reduction in damping and shock absorption performance, were significant influenced by the addition of the ceramic powder. Moreover, the cFIR composite films showed high far-infrared emissivity, which has the capability of prolonging the storage life of strawberries. This research demonstrates that cFIR composite films are promising for future applications. PMID:29186047

Properties and Applications of High Emissivity Composite Films Based on Far-Infrared Ceramic Powder.

PubMed

Xiong, Yabo; Huang, Shaoyun; Wang, Wenqi; Liu, Xinghai; Li, Houbin

2017-11-29

Polymer matrix composite materials that can emit radiation in the far-infrared region of the spectrum are receiving increasing attention due to their ability to significantly influence biological processes. This study reports on the far-infrared emissivity property of composite films based on far-infrared ceramic powder. X-ray fluorescence spectrometry, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray powder diffractometry were used to evaluate the physical properties of the ceramic powder. The ceramic powder was found to be rich in aluminum oxide, titanium oxide, and silicon oxide, which demonstrate high far-infrared emissivity. In addition, the micromorphology, mechanical performance, dynamic mechanical properties, and far-infrared emissivity of the composite were analyzed to evaluate their suitability for strawberry storage. The mechanical properties of the far-infrared radiation ceramic (cFIR) composite films were not significantly influenced ( p ≥ 0.05) by the addition of the ceramic powder. However, the dynamic mechanical analysis (DMA) properties of the cFIR composite films, including a reduction in damping and shock absorption performance, were significant influenced by the addition of the ceramic powder. Moreover, the cFIR composite films showed high far-infrared emissivity, which has the capability of prolonging the storage life of strawberries. This research demonstrates that cFIR composite films are promising for future applications.

Electrical and switching properties of the Se 90Te 10-xAg x (0⩽ x⩽6) films

NASA Astrophysics Data System (ADS)

Afifi, M. A.; Hegab, N. A.; Bekheet, A. E.; Sharaf, E. R.

2009-08-01

Amorphous Se 90Te 10-xAg x (0⩽ x⩽6) films are obtained by thermal evaporation technique under vacuum from the synthesized bulk materials on pyrographite and glass substrates. X-ray analysis shows the amorphous nature of the obtained films. The dc electrical conductivity was studied for different thicknesses (165-711 nm) as a function of temperature in the range (298-323 K) below the corresponding T g for the studied films. The obtained results show that the conduction activation energy has a single value through the investigated range of temperature which can be explained in accordance with Mott and Davis model. The I- V characteristic curves for the film compositions are found to be typical for a memory switch. The mean value of the threshold voltage Vbar increases linearly with increasing film thickness (165-711 nm), while it decreases exponentially with increasing temperature in the investigated range for the studied compositions. The results are explained in accordance with the electrothermal model for the switching process. The effect of Ag on the studied parameters is also investigated.

Model Lung Surfactant Films: Why Composition Matters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Selladurai, Sahana L.; Miclette Lamarche, Renaud; Schmidt, Rolf

Lung surfactant replacement therapies, Survanta and Infasurf, and two lipid-only systems both containing saturated and unsaturated phospholipids and one containing additional palmitic acid were used to study the impact of buffered saline on the surface activity, morphology, rheology, and structure of Langmuir monolayer model membranes. Isotherms and Brewster angle microscopy show that buffered saline subphases induce a film expansion, except when the cationic protein, SP-B, is present in sufficient quantities to already screen electrostatic repulsion, thus limiting the effect of changing pH and adding counterions. Grazing incidence X-ray diffraction results indicate an expansion not only of the liquid expanded phasemore » but also an expansion of the lattice of the condensed phase. The film expansion corresponded in all cases with a significant reduction in the viscosity and elasticity of the films. The viscoelastic parameters are dominated by liquid expanded phase properties and do not appear to be dependent on the structure of the condensed phase domains in a phase separated film. The results highlight that the choice of subphase and film composition is important for meaningful interpretations of measurements using model systems.« less

Epitaxy, strain, and composition effects on metal-insulator transition characteristics of SmNiO{sub 3} thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aydogdu, Gulgun H.; Ha, Sieu D.; Viswanath, B.

SmNiO{sub 3} (SNO) thin films were deposited on LaAlO{sub 3} (LAO), SrTiO{sub 3}, SrLaAlO{sub 4}, Si, and Al{sub 2}O{sub 3} (sapphire) substrates by RF magnetron sputtering and studies were conducted to understand how film structure and composition influence the insulator-metal transition properties. It is observed that the compressive strain induces the insulator to metal transition (MIT), while tensile strain suppresses it. In the case of non-epitaxial films, semiconducting behavior is obtained on sapphire over a broad temperature range, while on heavily-doped Si substrate; an MIT is seen in out-of-plane resistance measurement. In addition, thickness dependence on the resistance behavior andmore » nickel oxidation state has been examined for epitaxial SNO films on LAO substrates. Fine control of the MIT by modifications to the mismatch strain and thickness provides insights to enhance the performance and the functionality of these films for emerging electron devices.« less

Multiwall carbon nanotube and poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) composite films for transistor and inverter devices.

PubMed

Yun, Dong-Jin; Hong, KiPyo; Kim, Se hyun; Yun, Won-Min; Jang, Jae-young; Kwon, Woo-Sung; Park, Chan-Eon; Rhee, Shi-Woo

2011-01-01

Highly conductive multiwalled carbon nanotube (MWNT)/Poly(3,4-ethylenedioxythiophene) polymerized with poly(4-styrenesulfonate) (PEDOT:PSS) films were prepared by spin coating a mixture solution. The solution was prepared by dispersing MWNT in the PEDOT:PSS solution in water using ultrasonication without any oxidation process. The effect of the MWNT loading in the solution on the film properties such as surface roughness, work function, surface energy, optical transparency, and conductivity was studied. The conductivity of MWNT/PEDOT:PSS composite film was increased with higher MWNT loading and the high conductivity of MWNT/PEDOT:PSS films enabled them to be used as a source/drain electrode in organic thin film transistor (OTFT). The pentacene TFT with MWNT/PEDOT:PSS S/D electrode showed much higher performance with mobility about 0.2 cm²/(V s) and on/off ratio about 5 × 10⁵ compared to that with PEDOT:PSS S/D electrode (∼0.05 cm²/(V s), 1 × 10⁵). The complementary inverters exhibited excellent characteristics, including high gain value of about 30.

Piezoelectric and Triboelectric Dual Effects in Mechanical-Energy Harvesting Using BaTiO3/Polydimethylsiloxane Composite Film.

PubMed

Suo, Guoquan; Yu, Yanhao; Zhang, Zhiyi; Wang, Shifa; Zhao, Ping; Li, Jianye; Wang, Xudong

2016-12-21

Piezoelectric and triboelectric nanogenerators have been developed as rising energy-harvesting devices in the past few years to effectively convert mechanical energy into electricity. Here, a novel hybrid piezo/triboelectric nanogenerator based on BaTiO 3 NP/PDMS composite film was developed in a simple and low-cost way. The effects of the BTO content and polarization degree on the output performance were systematically studied. The device with 20 wt % BTO in PDMS and a 100-μm-thick film showed the highest output power. We also designed three measurement modes to record hybrid, triboelectric, and piezoelectric outputs separately with a simple structure that has only two electrodes. The hybrid output performance is higher than the tribo- and piezoelectric performances. This work will provide not only a new way to enhance the output power of nanogenerators, but also new opportunities for developing built-in power sources in self-powered electronics.

The effect of annealing on structural, optical and electrical properties of ZnS/porous silicon composites

NASA Astrophysics Data System (ADS)

Wang, Cai-Feng; Li, Qing-Shan; Hu, Bo; Li, Wei-Bing

2009-06-01

ZnS films were prepared by pulsed laser deposition (PLD) on porous silicon (PS) substrates. This paper investigates the effect of annealing temperature on the structural, morphological, optical and electrical properties of ZnS/PS composites by x-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence (PL) and I-V characteristics. It is found that the ZnS films deposited on PS substrates were grown in preferred orientation along β-ZnS (111) direction, and the intensity of diffraction peak increases with increasing annealing temperature, which is attributed to the grain growth and the enhancement of crystallinity of ZnS films. The smooth and uniform surface of the as-prepared ZnS/PS composite becomes rougher through annealing treatment, which is related to grain growth at the higher annealing temperature. With the increase of annealing temperature, the intensity of self-activated luminescence of ZnS increases, while the luminescence intensity of PS decreases, and a new green emission located around 550 nm appeared in the PL spectra of ZnS/PS composites which is ascribed to the defect-center luminescence of ZnS. The I-V characteristics of ZnS/PS heterojunctions exhibited rectifying behavior, and the forward current increases with increasing annealing temperature.

Gold-carbon composite thin films for electrochemical gas sensor prepared by reactive plasma sputtering

NASA Astrophysics Data System (ADS)

Okamoto, A.; Suzuki, Y.; Yoshitake, M.; Ogawa, S.; Nakano, N.

1997-01-01

We have investigated the properties of gold-carbon composite thin films prepared by a plasma sputtering deposition using argon and methane mixture gas. These composite films have an uneven surface in submicron scale or consist of nano-scale particles of gold polycrystalline. Such morphological properties can be controlled by the sputtering voltage and the partial pressure of methane gas. The working electrode of electrochemical gas sensor has needed a stable gas sensitivity and a good gas selectivity. Our composite film is one of the excellent candidates for a thin film working electrode of electrochemical gas sensor. It is described that the output current of sensor is related to the preparation conditions of the thin films and increase linearly as the concentration of PH 3 gas ranging from 0.1 to 1.0 ppm is increasing.

Fabrication of composite films containing zirconia and cationic polyelectrolytes.

PubMed

Pang, Xin; Zhitomirsky, Igor

2004-03-30

Composite films were prepared by electrophoretic deposition of poly(ethylenimine) or poly(allylamine hydrochloride) combined with cathodic precipitation of zirconia. Films of up to several micrometers thick were obtained on Ni, Pt, stainless-steel, graphite, and carbon-felt substrates. When the concentration of polyelectrolytes in solutions and the deposition time were varied, the amount of the deposited material and its composition can be varied. The electrochemical intercalation of yttria-stabilized zirconia particles into the composite films has been demonstrated. Obtained results pave the way for the electrodeposition of other polymer-ceramic composites. The deposits were studied by thermogravimetric analysis, X-ray diffraction analysis, scanning electron microscopy, and atomic force microscopy. The mechanisms of deposition are discussed.

Interface composition of InAs nanowires with Al2O3 and HfO2 thin films

NASA Astrophysics Data System (ADS)

Timm, R.; Hjort, M.; Fian, A.; Borg, B. M.; Thelander, C.; Andersen, J. N.; Wernersson, L.-E.; Mikkelsen, A.

2011-11-01

Vertical InAs nanowires (NWs) wrapped by a thin high-κ dielectric layer may be a key to the next generation of high-speed metal-oxide-semiconductor devices. Here, we have investigated the structure and chemical composition of the interface between InAs NWs and 2 nm thick Al2O3 and HfO2 films. The native oxide on the NWs is significantly reduced upon high-κ deposition, although less effective than for corresponding planar samples, resulting in a 0.8 nm thick interface layer with an In-/As-oxide composition of about 0.7/0.3. The exact oxide reduction and composition including As-suboxides and the role of the NW geometry are discussed in detail.

Development of metal oxide impregnated stilbite thick film ethanol sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahabole, M. P., E-mail: kashinath.bogle@gmail.com; Lakhane, M. A.; Choudhari, A. L.

This paper presents the study of the sensing efficiency of Titanium oxide/ Stilbite and Copper oxide /Stilbite composites towards detection of hazardous pollutants like ethanol. Stilbite based composites are prepared by physically mixing zeolite with metal oxides namely TiO{sub 2} and CuO with weight ratios of 25:75, 50:50 and 75:25. The resulting sensor materials are characterized by X-ray diffraction and Fourier Transform Infrared Spectroscopy techniques. Composite sensors are fabricated in the form of thick film by using screen printing technique. The effect of metal oxide concentration on various ethanol sensing parameters such as operating temperature, maximum uptake capacity and response/recoverymore » time are investigated. The results indicate that metal oxide impregnated stilbite composites have great potential as low temperature ethanol sensor.« less

Development of metal oxide impregnated stilbite thick film ethanol sensor

NASA Astrophysics Data System (ADS)

Mahabole, M. P.; Lakhane, M. A.; Choudhari, A. L.; Khairnar, R. S.

2016-05-01

This paper presents the study of the sensing efficiency of Titanium oxide/ Stilbite and Copper oxide /Stilbite composites towards detection of hazardous pollutants like ethanol. Stilbite based composites are prepared by physically mixing zeolite with metal oxides namely TiO2 and CuO with weight ratios of 25:75, 50:50 and 75:25. The resulting sensor materials are characterized by X-ray diffraction and Fourier Transform Infrared Spectroscopy techniques. Composite sensors are fabricated in the form of thick film by using screen printing technique. The effect of metal oxide concentration on various ethanol sensing parameters such as operating temperature, maximum uptake capacity and response/recovery time are investigated. The results indicate that metal oxide impregnated stilbite composites have great potential as low temperature ethanol sensor.

Fabricating and strengthening the carbon nanotube/copper composite fibers with high strength and high electrical conductivity

NASA Astrophysics Data System (ADS)

Han, Baoshuai; Guo, Enyu; Xue, Xiang; Zhao, Zhiyong; Li, Tiejun; Xu, Yanjin; Luo, Liangshun; Hou, Hongliang

2018-05-01

Combining the excellent properties of carbon nanotube (CNT) and copper, CNT/Cu composite fibers were fabricated by physical vapor deposition (PVD) and rolling treatment. Dense and continuous copper film (∼2 μm) was coated on the surface of the CNT fibers by PVD, and rolling treatment was adopt to strengthen the CNT/Cu composite fibers. After the rolling treatment, the defects between the Cu grains and the CNT bundles were eliminated, and the structure of both the copper film and the core CNT fibers were optimized. The rolled CNT/Cu composite fibers possess high tensile effective strength (1.01 ± 0.13 GPa) and high electrical conductivity ((2.6 ± 0.3) × 107 S/m), and thus, this material may become a promising wire material.

Lead zirconate titanate-nickel zink ferrite thick-film composites: obtaining by the screen printing technique and magnetoelectric properties

NASA Astrophysics Data System (ADS)

Bush, A. A.; Shkuratov, V. Ya.; Chernykh, I. A.; Fetisov, Y. K.

2010-03-01

Layered thick-film composites containing one lead zirconate titanate (PZT) layer, one nickel zinc ferrite (NZF) layer, two PZT-NZF layers, or three PZT-NZF-PZT layers each 40-50 μm thick are prepared. The layers are applied by screen printing on a ceramic aluminum oxide substrate with a preformed contact (conducting) layer. The dielectric properties of the composites are studied in the temperature interval 80-900 K and the frequency interval 25 Hz-1 MHz. Polarized samples exhibit piezoelectric, pyroelectric, and magnetoelectric effects. In tangentially magnetized two- and three-layer composites, the magnetoelectric conversion factor equals 57 kV/(m T) at low frequencies and reaches 2000 kV/(m T) at the mechanical resonance frequency.

Composite HPMC and sodium alginate based buccal formulations for nicotine replacement therapy.

PubMed

Okeke, Obinna C; Boateng, Joshua S

2016-10-01

Smoking cessation is of current topical interest due to the significant negative health and economic impact in many countries. This study aimed to develop buccal films and wafers comprising HPMC and sodium alginate (SA) for potential use in nicotine replacement therapy via the buccal mucosa, as a cheap but effective alternative to currently used nicotine patch and chewing gum. The formulations were characterised using texture analyser (tensile and hardness, mucoadhesion), scanning electron microscopy, X-ray diffractometry, attenuated total reflection-Fourier transform infrared (ATR-FTIR), differential scanning calorimetry (DSC) and swelling capacity. Drug loaded films and wafers were characterised for content uniformity (HPLC) whilst the drug loaded wafers only were further characterised for in vitro drug dissolution. SA modified and improved the functional properties of HPMC at optimum ratio of HPMC: SA of 1.25: 0.75. Generally, both films and wafers (blank and drug loaded) were amorphous in nature which impacted on swelling and mucoadhesive performance. HPMC-SA composite wafers showed a porous internal morphology with higher mucoadhesion, swelling index and drug loading capacity compared to the HPMC-SA composite films which were non-porous. The study demonstrates the potential use of composite HPMC-SA wafers in the buccal delivery nicotine. Copyright © 2016 Elsevier B.V. All rights reserved.

Sensitive voltammetric determination of chloramphenicol by using single-wall carbon nanotube-gold nanoparticle-ionic liquid composite film modified glassy carbon electrodes.

PubMed

Xiao, Fei; Zhao, Faqiong; Li, Jiangwen; Yan, Rui; Yu, Jingjing; Zeng, Baizhao

2007-07-16

A novel composite film modified glassy carbon electrode has been fabricated and characterized by scanning electron microscope (SEM) and voltammetry. The composite film comprises of single-wall carbon nanotube (SWNT), gold nanoparticle (GNP) and ionic liquid (i.e. 1-octyl-3-methylimidazolium hexafluorophosphate), thus has the characteristics of them. The resulting electrode shows good stability, high accumulation efficiency and strong promotion to electron transfer. On it, chloramphenicol can produce a sensitive cathodic peak at -0.66 V (versus SCE) in pH 7.0 phosphate buffer solutions. Parameters influencing the voltammetric response of chloramphenicol are optimized, which include the composition of the film and the operation conditions. Under the optimized conditions, the peak current is linear to chloramphenicol concentration in the range of 1.0x10(-8)-6.0x10(-6) M, and the detection limit is estimated to be 5.0x10(-9) M after an accumulation for 150 s on open circuit. The electrode is applied to the determination of chloramphenicol in milk samples, and the recoveries for the standards added are 97.0% and 100.3%. In addition, the electrochemical reaction of chloramphenicol and the effect of single-wall carbon nanotube, gold nanoparticle and ionic liquid are discussed.

Superior environment resistance of quartz crystal microbalance with anatase TiO2/ZnO nanorod composite films

NASA Astrophysics Data System (ADS)

Qiang, Wei; Wei, Li; Shaodan, Wang; Yu, Bai

2015-08-01

The precise measurement of quartz crystal microbalance (QCM) in the detection and weighing of organic gas molecules is achieved due to excellent superhydrophobicity of a deposited film composite. Photocatalysis is utilized as a method for the self-cleaning of organic molecules on the QCM for extended long-term stability in the precision of the instrument. In this paper, ZnO nanorod array is prepared via in situ methods on the QCM coated with Au film via hydrothermal process. Subsequently, a TiO2/ZnO composite film is synthesized by surface modification with TiO2 via sol-gel methods. Results show the anatase TiO2/ZnO nanorod composite film with a sharp, pencil-like structure exhibiting excellent superhydrophobicity (water contact angle of 155°), non-sticking water properties, and an autonomous cleaning property under UV irradiation. The anatase TiO2/ZnO nanorod composite film facilitates the precise measurement and extended lifetime of the QCM for the detection of organic gas molecules.

Fabrication of Monolithic Sapphire Membranes for High T(sub c) Bolometer Array Development

NASA Technical Reports Server (NTRS)

Pugel, D. E.; Lakew, B.; Aslam, S.; Wang, L.

2004-01-01

This paper examines the effectiveness of Pt/Cr thin film masks for the architecture of monolithic membrane structures in r-plane single crystal sapphire. The development of a pinhole-free Pt/Cr composite mask that is resistant to boiling H2SO4:H3PO4 etchant will lead to the fabrication of smooth sapphire membranes whose surfaces are well-suited for the growth of low-noise high Tc films. In particular, the relationship of thermal annealing conditions on the Pt/Cr composite mask system to: (1) changes in the surface morphology (2) elemental concentration of the Pt/Cr thin film layers and (3) etch pit formation on the sapphire surface will be presented.

Influence of superconductor film composition on adhesion strength of coated conductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kesgin, Ibrahim; Khatri, Narayan; Liu, Yuhao

The effect of high temperature superconductor (HTS) film composition on the adhesion strength of rare- earth barium copper oxide coated conductors (CCs) has been studied. It has been found that the mechanical integrity of the superconductor layer is very susceptible to the defects especially those along the ab plane, probably due to the weak interfaces between the defects and the matrix. Gd and Y in the standard composition were substituted with Sm and the number of in-plane defects was drastically reduced. Consequently, a four-fold increase in adhesion or peeling strength in Sm-based CCs was achieved compared to the standard GdYBCOmore » samples.« less

Hydrogen film/conductive cooling

NASA Technical Reports Server (NTRS)

Ewen, R. L.

1972-01-01

Small scale nozzle tests using heated nitrogen were run to obtain effectiveness and wall heat transfer data with hydrogen film cooling. Effectiveness data are compared with an entrainment model developed from planar, unaccelerated flow data. Results indicate significant effects due to flow turning and acceleration. With injection velocity effects accounted for explicitly, heat transfer correlation coefficients were found to be the same with and without film cooling when properties are evaluated at an appropriate reference temperature for the local gas composition defined by the coolant effectiveness. A design study for an O2/H2 application with 300 psia (207 N/sq cm) chamber pressure and 1500 lbs (6670 N) thrust indicates an adiabatic wall design requires 4 to 5 percent of the total flow as hydrogen film cooling. Internal regenerative cooling designs were found to offer no reduction in coolant requirements.

Specific considerations for obtaining appropriate La1-xSrxGa1-yMgyO3-δ thin films using pulsed-laser deposition and its influence on the performance of solid-oxide fuel cells

NASA Astrophysics Data System (ADS)

Hwang, Jaeyeon; Lee, Heon; Lee, Jong-Ho; Yoon, Kyung Joong; Kim, Hyoungchul; Hong, Jongsup; Son, Ji-Won

2015-01-01

To obtain La1-xSrxGa1-yMgyO3-δ (LSGM) thin films with the appropriate properties, pulsed-laser deposition (PLD) is employed, and specific considerations regarding control of the deposition parameters is investigated. It is demonstrated that with a target of stoichiometric composition, appropriate LSGM thin films cannot be produced because of the deviation of the composition from the target to the thin film. Only after adjusting the target composition an LSGM thin film with an appropriate composition and phase can be obtained. The optimized LSGM thin film possesses an electrical conductivity close to that of the bulk LSGM. In contrast, non-optimized thin films do not yield any measurable electrical conductivity. The impact of the optimization of the LSGM thin-film electrolyte on the cell performance is quite significant, in that a solid-oxide fuel cell (SOFC) with an optimized LSGM thin-film electrolyte produces a maximum power density of 1.1 W cm-2 at 600 °C, whereas an SOFC with a non-optimal LSGM thin-film electrolyte is not operable.

MOCVD growth and study of thin films of indium nitride

NASA Astrophysics Data System (ADS)

Jain, Abhishek

This thesis is focused on a study of MOCVD growth of InN with the goal of providing new information on the effects of growth conditions and buffer/substrate materials on InN film properties. Initial studies, using both (111) Si and (0001) sapphire substrates, identified an optimum growth temperature window of 540--560°C for the formation of stable InN films. When attempting to grow InN films on sapphire with thicknesses greater than approximately 150 nanometers using an AlN buffer layer, the InN films were observed to delaminate from the buffer/substrate at growth temperature. The combined effect of compressive stress due to high lattice mismatch between InN and AlN (˜14%) and tensile stress due to grain coalescence along with the relatively weak bond strength of InN compared to GaN and AlN, is believed to cause the InN film to crack along the interface and delaminate. To further investigate the effect of the buffer layer on InN growth, studies were carried out using GaN films grown on sapphire as the growth template. Recent MBE results had indicated a significant difference in the thermal stability and growth mode of In-polar and N-polar InN, with improved properties reported for N-polar material grown on N-polar GaN. MOCVD growth of N-polar GaN is very difficult; consequently, all of the results reported in the literature for InN growth on GaN were likely carried out on Ga-polar material resulting in films with a high surface roughness. By utilizing N-polar and Ga-polar GaN films, it was possible to produce N-polar and In-polar InN films by MOCVD, as determined by convergent beam electron diffraction (CBED) analysis. Furthermore, the polarity was found to dramatically alter the surface roughness and growth mode of the InN films with enhanced lateral growth and reduced surface roughness obtained for N-polar InN. A qualitative model was proposed to explain the different growth mechanisms observed for In-polar and N-polar InN. In spite of the improvements in surface morphology obtained with growth of N-polar InN, delamination at the InN/GaN interface was still observed in these films, and was also present in In-polar InN samples. Attempts were made to further reduce the lattice mismatch and improve the adhesion between InN and GaN by using a compositionally graded InGaN buffer layer. The fabrication of InGaN over its entire composition range is challenging since the optimal growth parameters window for InGaN varies with composition and film quality is strongly dependent on temperature and precursor flow rates. The structural properties of the InN films grown on the graded InGaN layers were comparable to films grown directly on GaN, however, the film adhesion was significantly improved with no evidence of interfacial cracks between the InN and GaN. These preliminary results indicate that graded InGaN layers can be used to improve the adhesion of InN on both Ga-polar and N-polar GaN, however, further work is needed to develop graded InGaN buffer layers or constant composition InGaN interlayers with improved structural properties for InN growth. (Abstract shortened by UMI.)

Hydrophilic Modification of Multi-Walled Carbon Nanotube for Building Photonic Crystals with Enhanced Color Visibility and Mechanical Strength.

PubMed

Li, Feihu; Tang, Bingtao; Xiu, Jinghai; Zhang, Shufen

2016-04-28

Low color visibility and poor mechanical strength of polystyrene (PS) photonic crystal films have been the main shortcomings for the potential applications in paints or displays. This paper presents a simple method to fabricate PS/MWCNTs (multi-walled carbon nanotubes) composite photonic crystal films with enhanced color visibility and mechanical strength. First, MWCNTs was modified through radical addition reaction by aniline 2,5-double sulfonic acid diazonium salt to generate hydrophilic surface and good water dispersity. Then the MWCNTs dispersion was blended with PS emulsion to form homogeneous PS/MWCNTs emulsion mixtures and fabricate composite films through thermal-assisted method. The obtained films exhibit high color visibility under natural light and improved mechanical strength owing to the light-adsorption property and crosslinking effect of MWCNTs. The utilization of MWCNTs in improving the properties of photonic crystals is significant for various applications, such as in paints and displays.

Nonequilibrium segregation and phase instability in alloy films during elevated-temperature irradiation in a high-voltage electron microscope

NASA Astrophysics Data System (ADS)

Lam, N. Q.; Okamoto, P. R.

1984-05-01

The effects of defect-production rate gradients, caused by the radial nonuniformity in the electron flux distribution, on solute segregation and phase stability in alloy films undergoing high-voltage electron-microscope (HVEM) irradiation at high temperatures are assessed. Two-dimensional (axially symmetric) compositional redistributions were calculated, taking into account both axial and transverse radial defect fluxes. It was found that when highly focused beams were employed radiation-induced segregation consisted of two stages: dominant axial segregation at the film surfaces at short irradiation times and competitive radial segregation at longer times. The average alloy composition within the irradiated region could differ greatly from that irradiated with a uniform beam, because of the additional atom transport from or to the region surrounding the irradiated zone under the influence of radial fluxes. Damage-rate gradient effects must be taken into account when interpreting in-situ HVEM observations of segregation-induced phase instabilities. The theoretical predictions are compared with experimental observations of the temporal and spatial dependence of segregation-induced precipitation in thin films of Ni-Al, Ni-Ge and Ni-Si solid solutions.

Fully solution-processed transparent electrodes based on silver nanowire composites for perovskite solar cells.

PubMed

Kim, Areum; Lee, Hongseuk; Kwon, Hyeok-Chan; Jung, Hyun Suk; Park, Nam-Gyu; Jeong, Sunho; Moon, Jooho

2016-03-28

We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ∼80% at 550 nm and sheet resistance of 18 Ω sq(-1). Perovskite solar cells fabricated using a fully solution-processed transparent conductive electrode, Au/spiro-OMeTAD/CH3NH3PbI3 + m-Al2O3/ZnO/ITO/AgNW/ITO, exhibited a power conversion efficiency of 8.44% (comparable to that of the FTO/glass-based counterpart at 10.81%) and were stable for 30 days in ambient air. Our results demonstrate the feasibility of using AgNWs as a transparent bottom electrode in perovskite solar cells produced by a fully printable process.

Antimicrobial activity of allyl isothiocyanate used to coat biodegradable composite films as affected by storage and handling conditions.

PubMed

Li, Weili; Liu, Linshu; Jin, Tony Z

2012-12-01

We evaluated the effects of storage and handling conditions on the antimicrobial activity of biodegradable composite films (polylactic acid and sugar beet pulp) coated with allyl isothiocyanate (AIT). Polylactic acid and chitosan were incorporated with AIT and used to coat one side of the film. The films were subjected to different storage conditions (storage time, storage temperature, and packed or unpacked) and handling conditions (washing, abrasion, and air blowing), and the antimicrobial activity of the films against Salmonella Stanley in tryptic soy broth was determined. The films (8.16 μl of AIT per cm(2) of surface area) significantly (P < 0.05) inhibited the growth of Salmonella during 24 h of incubation at 22°C, while the populations of Salmonella in controls increased from ca. 4 to over 8 log CFU/ml, indicating a minimum inactivation of 4 log CFU/ml on films in comparison to the growth on controls. Statistical analyses indicated that storage time, storage temperature, and surface abrasion affected the antimicrobial activity of the films significantly (P < 0.05). However, the differences in microbial reduction between those conditions were less than 0.5 log cycle. The results suggest that the films' antimicrobial properties are stable under practical storage and handling conditions and that these antimicrobial films have potential applications in food packaging.

Polymer nanomechanics: Separating the size effect from the substrate effect in nanoindentation

NASA Astrophysics Data System (ADS)

Li, Le; Encarnacao, Lucas M.; Brown, Keith A.

2017-01-01

While the moduli of thin polymer films are known to deviate dramatically from their bulk values, there is not a consensus regarding the nature of this size effect. In particular, indenting experiments appear to contradict results from both buckling experiments and molecular dynamics calculations. In this letter, we present a combined computational and experimental method for measuring the modulus of nanoindented soft films on rigid substrates that reconciles this discrepancy. Through extensive finite element simulation, we determine a correction to the Hertzian contact model that separates the substrate effect from the thickness-dependent modulus of the film. Interestingly, this correction only depends upon a dimensionless film thickness and the Poisson ratio of the film. To experimentally test this approach, we prepared poly(methyl methacrylate), polystyrene, and parylene films with thicknesses ranging from 20 to 300 nm and studied these films using atomic force microscope-based nanoindenting. Strikingly, when experiments were interpreted using the computationally derived substrate correction, sub-70 nm films were found to be softer than bulk, in agreement with buckling experiments and molecular dynamics studies. This correction can serve as a general method for unambiguously determining the size effect of thin polymer films and ultimately lead to the ability to quantitatively image the mechanical properties of heterogeneous materials such as composites.

The effects of incidence angle on film dosimetry and their consequences in IMRT dose verification.

PubMed

Srivastava, R P; De Wagter, C

2012-10-01

The dosimetric accuracy of EDR2 radiographic film has been rigorously assessed in regular and intensity modulated beams for various incidence angles, including the parallel and perpendicular orientation. There clearly exists confusion in literature regarding the effect of film orientation. The primary aim is to clarify potential sources of the confusion and to gain physical insight into the film orientation effect with a link to radiochromic film as well. An inverse pyramid IMRT field, consisting of six regular and elongated 3 × 20 cm(2) field segments, was studied in perpendicular and parallel orientation. Assessment of film self-perturbation and intrinsic directional sensitivity were also included in the experiments. Finally, the authors investigated the orientational effect in composite beams in the two extreme orientations, i.e., perpendicular and parallel. The study of an inverse pyramid dose profile revealed good agreement between the perpendicular film and the diamond detector within 0.5% in the low-scatter regions for both 6 and 18 MV. The parallel oriented film demonstrated a 3% under-response at 5-cm (6 MV) depth against the perpendicular orientation, but both orientations over responded equally in the central region, which received only scattered dose, at both 5- and 20-cm depths. In a regular 6-MV 5 × 5 cm(2) field, a 4.1% lower film response was observed in the parallel orientation compared to perpendicular orientation. The under response gradually increased to 6% when reducing the field size to 0.5 × 5 cm(2). On the other hand, the film showed a 1.7% lower response in parallel orientation for the large field size of 20 × 20 cm(2) at 5-cm depth but the difference disappeared at 10 cm. At 18 MV, similar but somewhat lower differences were found between the two orientations. The directional sensitivity of the film diminishes with increasing field size and depth. Surprisingly a composite IMRT beam consisting of 20 adjacent strip segments also produced a significant orientational dependence of film response, notwithstanding the large total field size of 20 × 20 cm(2). This analysis allowed the development of a hypothesis about the physics behind the orientational dependence of film response in general and to formulate precautions when using film dosimetry in the dosimetric verification of multibeam treatments.

High-loading Fe2O3/SWNT composite films for lithium-ion battery applications

NASA Astrophysics Data System (ADS)

Wang, Ying; Guo, Jiahui; Li, Li; Ge, Yali; Li, Baojun; Zhang, Yingjiu; Shang, Yuanyuan; Cao, Anyuan

2017-08-01

Single-walled carbon nanotube (SWNT) films are a potential candidate as porous conductive electrodes for energy conversion and storage; tailoring the loading and distribution of active materials grafted on SWNTs is critical for achieving maximum performance. Here, we show that as-synthesized SWNT samples containing residual Fe catalyst can be directly converted to Fe2O3/SWNT composite films by thermal annealing in air. The mass loading of Fe2O3 nanoparticles is tunable from 63 wt% up to 96 wt%, depending on the annealing temperature (from 450 °C to 600 °C), while maintaining the porous network structure. Interconnected SWNT networks containing high-loading active oxides lead to synergistic effect as an anode material for lithium ion batteries. The performance is improved consistently with increasing Fe2O3 loading. As a result, our Fe2O3/SWNT composite films exhibit a high reversible capacity (1007.1 mA h g-1 at a current density of 200 mA g-1), excellent rate capability (384.9 mA h g-1 at 5 A g-1) and stable cycling performance with the discharge capacity up to 567.1 mA h g-1 after 600 cycles at 2 A g-1. The high-loading Fe2O3/SWNT composite films have potential applications as nanostructured electrodes for various energy devices such as supercapacitors and Li-ion batteries.

Influence of high loading of cellulose nanocrystals in polyacrylonitrile composite films

Treesearch

Jeffrey Luo; Huibin Chang; Amir A. Bakhtiary Davijani; H. Clive Liu; Po-Hsiang Wang; Robert J. Moon; Satish Kumar

2017-01-01

Polyacrylonitrile-co-methacrylic acid (PAN-co-MAA) and cellulose nanocrystal (CNC) composite films were produced with up to 40 wt% CNC loading through the solution casting method. The rheological properties of the solution/suspensions and the structural, optical, thermal, and mechanical properties of the resulting films were investigated. The viscosity of the composite...

Structural and water diffusion of poly(acryl amide)/poly(vinyl alcohol) blend films: Experiment and molecular dynamics simulations.

PubMed

Wang, Yanen; Wei, Qinghua; Wang, Shuzhi; Chai, Weihong; Zhang, Yingfeng

2017-01-01

To study the effects of composition ratios and temperature on the diffusion of water molecules in PVA/PAM blend films, five simulation models of PVA/PAM with ten water molecules at different composition ratios (4/0, 3/1, 2/2, 1/3, 0/4) were constructed and simulated by using a molecular dynamics (MD) simulation. The diffusion behavior of water molecules in blends were investigated from the aspects of the diffusion coefficient, free volume, pair correlation function (PCF) and trajectories of water molecules, respectively. And the hydrophilicity of blend composite was studied based on the contact angle and equilibrium water content (EWC) of the blend films. The simulation results show that the diffusion coefficient of water molecules and fractional free volume (FFV) of blend membranes increase with the addition of PAM, and a higher temperature can also improve the diffusion of water molecules. Additionally, the analysis of PCFs reveals the main reason why the diffusion coefficient of water in blend system increases with the addition of PAM. The measurement results of contact angle and EWC of blend films indicate that the hydrophilicity of blend films decreases with the addition of PAM, but the EWC of blends increases with the addition of PAM. Copyright © 2016 Elsevier Inc. All rights reserved.

ZrO{sub 2}-ZnO composite thin films for humidity sensing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Velumani, M., E-mail: velumanimohan@gmail.com; Sivacoumar, R.; Alex, Z. C.

2016-05-23

ZrO{sub 2}-ZnO composite thin films were grown by reactive DC magnetron sputtering. X-ray diffraction studies reveal the composite nature of the films with separate ZnO and ZrO{sub 2} phase. Scanning electron microscopy studies confirm the nanocrystalline structure of the films. The films were studied for their impedometric relative humidity (RH) sensing characteristics. The complex impedance plot was fitted with a standard equivalent circuit consisting of an inter-granular resistance and a capacitance in parallel. The DC resistance was found to be decreasing with increase in RH.

A dense and strong bonding collagen film for carbon/carbon composites

NASA Astrophysics Data System (ADS)

Cao, Sheng; Li, Hejun; Li, Kezhi; Lu, Jinhua; Zhang, Leilei

2015-08-01

A strong bonding collagen film was successfully prepared on carbon/carbon (C/C) composites. The surface conditions of the modified C/C composites were detected by contact angle measurements, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectra. The roughness, optical morphology, bonding strength and biocompatibility of collagen films at different pH values were detected by confocal laser scanning microscope (CLSM), universal test machine and cytology tests in vitro. After a 4-h modification in 30% H2O2 solution at 100 °C, the contact angle on the surface of C/C composites was decreased from 92.3° to 65.3°. Large quantities of hydroxyl, carboxyl and carbonyl functional groups were formed on the surface of the modified C/C composites. Then a dense and continuous collagen film was prepared on the modified C/C substrate. Bonding strength between collagen film and C/C substrate was reached to 8 MPa level when the pH value of this collagen film was 2.5 after the preparing process. With 2-day dehydrathermal treatment (DHT) crosslinking at 105 °C, the bonding strength was increased to 12 MPa level. At last, the results of in vitro cytological test showed that this collagen film made a great improvement on the biocompatibility on C/C composites.

Electronic structure of cyclodextrin–carbon nanotube composite films

DOE PAGES

Jeong, Hae Kyung; Echeverria, Elena; Chakraborti, Priyanka; ...

2017-02-10

The electronic structures of two kinds of cyclodextrin–carbon nanotube (αCD–CNT and γCD–CNT) composite films are investigated by using (angular dependent) photoelectron spectroscopy to gain insight as to why the αCD–CNT and γCD–CNT composite films show different performances in biosensor applications. The γCD–CNT composite film is likely to have the CD localized on the surface rather than in the bulk of the film, while αCD–CNT has CD relatively more concentrated within the bulk of selvedge region of the film, rather than the surface. The results indicate that the CD, of the γCD–CNT composite, may be more bioactive, and possibly a bettermore » sensor of biomolecules due to the favorable surface position compared with that of αCD–CNT. The valence band of αCD–CNT and γCD–CNT show little difference from the CNT film except for a density of states, originating from CD, evident at a binding energy near 27 eV below Fermi level, meaning that there are few or no redox interactions between the CD and the CNT. The absence of a redox interaction between the CD and the CNT permits a clear electrochemical response to occur when guest biomolecules are captured on the composites, providing a route to biosensor applications.« less

In situ X-ray monitoring of damage accumulation in SiC/RBSN tensile specimens

NASA Technical Reports Server (NTRS)

Baaklini, George Y.; Bhatt, Ramkrishna T.

1991-01-01

The room-temperature tensile testing of silicon carbide fiber reinforced reaction-bonded silicon nitride (SiC/RBSN) composite specimens was monitored by using in-situ X-ray film radiography. Radiographic evaluation before, during, and after loading provided data on the effect of preexisting volume flaws (high density impurities, and local density variations) on the fracture behavior of composites. Results from (O)1, (O)3, (O)5, and (O)8 composite specimens showed that X-ray film radiography can monitor damage accumulations during tensile loading. Matrix cracking, fiber-matrix debonding, and fiber pullout were imaged throughout the tensile loading history of the specimens. Further, in-situ film radiography was found to be a helpful and practical technique for estimating interfacial shear strength between the SiC fiber and the RBSN matrix by the matrix crack spacing method. It is concluded that pretest, in-situ, and post-test radiography can provide for a greater understanding of ceramic matrix composite mechanical behavior, a verification of related experimental procedures, and a validation and development of related analytical models.

In-situ x-ray monitoring of damage accumulation in SiC/RBSN tensile specimens

NASA Technical Reports Server (NTRS)

Baaklini, George Y.; Bhatt, Ramakrishna T.

1991-01-01

The room-temperature tensile testing of silicon carbide fiber reinforced reaction-bonded silicon nitride (SiC/RBSN) composite specimens was monitored by using in-situ x ray film radiography. Radiographic evaluation before, during, and after loading provided data on the effect of preexisting volume flaws (high density impurities, and local density variations) on the fracture behavior of composites. Results from (0)1, (0)3, (0)5, and (0)8 composite specimens, showed that x ray film radiography can monitor damage accumulations during tensile loading. Matrix cracking, fiber-matrix debonding, and fiber pullout were imaged throughout the tensile loading history of the specimens. Further, in-situ film radiography was found to be a helpful and practical technique for estimating interfacial shear strength between the SiC fiber and the RBSN matrix by the matrix crack spacing method. It is concluded that pretest, in-situ, and post-test radiography can provide for a greater understanding of ceramic matrix composite mechanical behavior, a verification of related experimental procedures, and a validation and development of related analytical models.

Effect of Si on DC arc plasma generation from Al-Cr and Al-Cr-Si cathodes used in oxygen

NASA Astrophysics Data System (ADS)

Zhirkov, I.; Landälv, L.; Göthelid, E.; Ahlgren, M.; Eklund, P.; Rosen, J.

2017-02-01

Al2O3 alloyed with Cr is an important material for the tooling industry. It can be synthesized from an arc discharge using Al-Cr cathodes in an oxygen atmosphere. Due to formation of Al-rich oxide islands on the cathode surface, the arc process stability is highly sensitive to oxygen pressure. For improved stability, the use of Al0.70Cr0.25Si0.05 cathodes has previously been suggested, where Si may reduce island formation. Here, we have investigated the effect of Si by comparing plasma generation and thin film deposition from Al0.7Cr0.3 and Al0.7Cr0.25Si0.05 cathodes. Plasma ion composition, ion energies, ion charge states, neutral species, droplet formation, and film composition have been characterized at different O2 flow rates for arc currents of 60 and 90 A. Si and related compounds are detected in plasma ions and in plasma neutrals. Scanning electron microscopy and energy dispersive X-ray analysis show that the cathode composition and the film composition are the same, with Si present in droplets as well. The effect of Si on the process stability, ion energies, and ion charge states is found to be negligible compared to that of the arc current. The latter is identified as the most relevant parameter for tuning the properties of the reactive discharge. The present work increases the fundamental understanding of plasma generation in a reactive atmosphere, and provides input for the choice of cathode composition and process parameters in reactive DC arc synthesis.

Effects of lead on oxidation behavior of Alloy 690TT within a high temperature aqueous environment

NASA Astrophysics Data System (ADS)

Hou, Qiang; Liu, Zhiyong; Li, Chengtao; Li, Xiaogang

2017-12-01

The chemical compositions, phases and structures of two oxide films on Alloy 690TT following exposure for 4400 h in pure water with and without lead at 320 °C were studied by surface analysis techniques. The analysis of a lead-doped oxide film prepared by a focused ion beam (FIB) demonstrated that both Cr-rich and Ni-rich oxides were alternatively distributed within the outer layer, whereas the inner layer was porous and poorly protected, causing severe corrosion of the alloy and a thicker film was formed. A duplex film model was proposed for the effects discussion of lead on the oxidation mechanism.

(GameChanger) Multifunctional Design of Hybrid Composites of Load Bearing Antennas

DTIC Science & Technology

2011-06-01

5 . Solvent Effect in Dynamic Superstructures from Au Nanoparticles and CdTe Nanowires: Experimental Observation and Theoretical Description , J. Phys...the magnetic bias is transverse to the propagation direction and the plane of the thin films . Such field displacement effect is used in several...within the structure, resulting from the material properties of the media. The magnetoelectric thin film with a DC magnetic field bias serves as a

Fabrication of Ti substrate grain dependent C/TiO2 composites through carbothermal treatment of anodic TiO2.

PubMed

Rüdiger, Celine; Favaro, Marco; Valero-Vidal, Carlos; Calvillo, Laura; Bozzolo, Nathalie; Jacomet, Suzanne; Hejny, Clivia; Gregoratti, Luca; Amati, Matteo; Agnoli, Stefano; Granozzi, Gaetano; Kunze-Liebhäuser, Julia

2016-04-07

Composite materials of titania and graphitic carbon, and their optimized synthesis are highly interesting for application in sustainable energy conversion and storage. We report on planar C/TiO2 composite films that are prepared on a polycrystalline titanium substrate by carbothermal treatment of compact anodic TiO2 with acetylene. This thin film material allows for the study of functional properties of C/TiO2 as a function of chemical composition and structure. The chemical and structural properties of the composite on top of individual Ti substrate grains are examined by scanning photoelectron microscopy and micro-Raman spectroscopy. Through comparison of these data with electron backscatter diffraction, it is found that the amount of generated carbon and the grade of anodic film crystallinity correlate with the crystallographic orientation of the Ti substrate grains. On top of Ti grains with ∼(0001) orientations the anodic TiO2 exhibits the highest grade of crystallinity, and the composite contains the highest fraction of graphitic carbon compared to Ti grains with other orientations. This indirect effect of the Ti substrate grain orientation yields new insights into the activity of TiO2 towards the decomposition of carbon precursors.

Nonvolatile memory thin film transistors using CdSe/ZnS quantum dot-poly(methyl methacrylate) composite layer formed by a two-step spin coating technique

NASA Astrophysics Data System (ADS)

Chen, Ying-Chih; Huang, Chun-Yuan; Yu, Hsin-Chieh; Su, Yan-Kuin

2012-08-01

The nonvolatile memory thin film transistors (TFTs) using a core/shell CdSe/ZnS quantum dot (QD)-poly(methyl methacrylate) (PMMA) composite layer as the floating gate have been demonstrated, with the device configuration of n+-Si gate/SiO2 insulator/QD-PMMA composite layer/pentacene channel/Au source-drain being proposed. To achieve the QD-PMMA composite layer, a two-step spin coating technique was used to successively deposit QD-PMMA composite and PMMA on the insulator. After the processes, the variation of crystal quality and surface morphology of the subsequent pentacene films characterized by x-ray diffraction spectra and atomic force microscopy was correlated to the two-step spin coating. The crystalline size of pentacene was improved from 147.9 to 165.2 Å, while the degree of structural disorder was decreased from 4.5% to 3.1% after the adoption of this technique. In pentacene-based TFTs, the improvement of the performance was also significant, besides the appearances of strong memory characteristics. The memory behaviors were attributed to the charge storage/discharge effect in QD-PMMA composite layer. Under the programming and erasing operations, programmable memory devices with the memory window (Δ Vth) = 23 V and long retention time were obtained.

Screen-Printed Fabrication of PEDOT:PSS/Silver Nanowire Composite Films for Transparent Heaters.

PubMed

He, Xin; He, Ruihui; Lan, Qiuming; Wu, Weijie; Duan, Feng; Xiao, Jundong; Zhang, Mei; Zeng, Qingguang; Wu, Jianhao; Liu, Junyan

2017-02-23

A transparent and flexible film heater was fabricated; based on a hybrid structure of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) and silver nanowires (Ag NWs) using a screen printing; which is a scalable production technology. The resulting film integrates the advantages of the two conductive materials; easy film-forming and strong adhesion to the substrate of the polymer PEDOT:PSS; and high conductivity of the Ag NWs. The fabricated composite films with different NW densities exhibited the transmittance within the range from 82.3% to 74.1% at 550 nm. By applying 40 V potential on the films; a stable temperature from 49 °C to 99 °C was generated within 30 s to 50 s. However; the surface temperature of the pristine PEDOT:PSS film did not increase compared to the room temperature. The composite film with the transmittance of 74.1% could be heated to the temperatures from 41 °C to 99 °C at the driven voltages from 15 V to 40 V; indicating that the film heater exhibited uniform heating and rapid thermal response. Therefore; the PEDOT:PSS/Ag NW composite film is a promising candidate for the application of the transparent and large-scale film heaters.

Temperature-controlled transparent-film heater based on silver nanowire-PMMA composite film

NASA Astrophysics Data System (ADS)

He, Xin; Liu, A.'lei; Hu, Xuyang; Song, Mingxia; Duan, Feng; Lan, Qiuming; Xiao, Jundong; Liu, Junyan; Zhang, Mei; Chen, Yeqing; Zeng, Qingguang

2016-11-01

We fabricated a high-performance film heater based on a silver nanowire and polymethyl methacrylate (Ag NW-PMMA) composite film, which was synthesized with the assistance of mechanical lamination and an in situ transfer method. The films exhibit excellent conductivity, high figure of merit, and strong adhesion of percolation network to substrate. By controlling NW density, we prepared the films with a transmittance of 44.9-85.0% at 550 nm and a sheet resistance of 0.13-1.40 Ω sq-1. A stable temperature ranging from 130 °C-40 °C was generated at 3.0 V within 10-30 s, indicating that the resulting film heaters show a rapid thermal response, low driving voltage and stable temperature recoverability. Furthermore, we demonstrated the applications of the film heater in defrosting and a physical therapeutic instrument. A fast defrosting on the composite film with a transmittance of 88% was observed by applying a 9 V driving voltage for 20 s. Meanwhile, we developed a physical therapeutic instrument with two modes of thermotherapy and electronic-pulse massage by using the composite films as two electrodes, greatly decreasing the weight and power consumption compared to a traditional instrument. Therefore, Ag NW-PMMA film can be a promising candidate for diversified heating applications.

A Facile Pathway to Modify Cellulose Composite Film by Reducing Wettability and Improving Barrier towards Moisture.

PubMed

Hu, Xiaorong; Chen, Lin; Tao, Dandan; Ma, Zhaocheng; Liu, Shilin

2017-01-05

The hydrophilic property of cellulose is a key limiting factor for its wide application. Here, a novel solution impregnation pathway was developed to increase the hydrophobic properties of cellulose. When compared with the regenerated cellulose (RC), the composite films showed a decrease in water uptake ability towards water vapor, and an increase of the water contact angle from 29° to 65° with increasing resin content in the composites, with only a slight change in the transmittance. Furthermore, the Young's modulus value increased from 3.2 GPa (RC film) to 5.1 GPa (RCBEA50 film). The results indicated that the composites had combined the advantages of cellulose and biphenyl A epoxy acrylate prepolymer (BEA) resin. The presented method has great potential for the preparation of biocomposites with improved properties. The overall results suggest that composite films can be used as high-performance packaging materials.

A Facile Pathway to Modify Cellulose Composite Film by Reducing Wettability and Improving Barrier towards Moisture

PubMed Central

Hu, Xiaorong; Chen, Lin; Tao, Dandan; Ma, Zhaocheng; Liu, Shilin

2017-01-01

The hydrophilic property of cellulose is a key limiting factor for its wide application. Here, a novel solution impregnation pathway was developed to increase the hydrophobic properties of cellulose. When compared with the regenerated cellulose (RC), the composite films showed a decrease in water uptake ability towards water vapor, and an increase of the water contact angle from 29° to 65° with increasing resin content in the composites, with only a slight change in the transmittance. Furthermore, the Young’s modulus value increased from 3.2 GPa (RC film) to 5.1 GPa (RCBEA50 film). The results indicated that the composites had combined the advantages of cellulose and biphenyl A epoxy acrylate prepolymer (BEA) resin. The presented method has great potential for the preparation of biocomposites with improved properties. The overall results suggest that composite films can be used as high-performance packaging materials. PMID:28772399

Fundamental aspects of polyimide dry film and composite lubrication: A review

NASA Technical Reports Server (NTRS)

Fusaro, R. L.

1982-01-01

The tribological properties of polyimide dry films and composites are reviewed. Friction coefficients, wear rates, transfer film characteristics, wear surface morphology, and possible wear mechanisms of several different polyimide films, polyimide-bonded solid lubricants, polyimide solid bodies, and polyimide composites are discussed. Such parameters as temperature, type of atmosphere, load, contact stress, and specimen configuration are investigated. Data from an accelerated test device (Pin-on-Disk) are compared to similar data obtained from an end use application test device (plain spherical bearing).

Compositional and structural analysis of nitrogen incorporated and ion implanted diamond thin films

NASA Astrophysics Data System (ADS)

Garratt, Elias James

Significant progress in area of nano-structured thin film systems has taken place in recent decades. In particular, diamond thin film systems are being widely studied for their wear resistant, optical and electronic properties. Of the various methods researchers use to modify the structure of such films, three techniques in particular are of interest due to their versatility: modification of the growth atmosphere, growth on metalized substrates, providing an interfacial layer, and modification through post-growth ion implantation. The aim of this study is to investigate the effects each has to the structure and composition of elements. Different techniques are applied in each section; nitrogen gas dilution in a microwave plasma CVD system, diamond deposition on a metal interfacial layer and ion implantation in thin nanocrystalline diamond film. The forms of nanocrystalline diamond film resulting from such modifications are investigated using advanced spectroscopic and spectrometric techniques, as well as mechanical testing and surface mapping. The impact of these characterizations will provide valuable perspective to researchers in materials science. Understanding the changes to the structure and properties of this class of thin films, which can be induced through various mechanisms, will allow future researchers to refine these films towards technological applications in areas of hard coatings, electronics and photonics.

Influence of Water on Chemical Vapor Deposition of Ni and Co thin films from ethanol solutions of acetylacetonate precursors

PubMed Central

Weiss, Theodor; Zielasek, Volkmar; Bäumer, Marcus

2015-01-01

In chemical vapor deposition experiments with pulsed spray evaporation (PSE-CVD) of liquid solutions of Ni and Co acetylacetonate in ethanol as precursors, the influence of water in the feedstock on the composition and growth kinetics of deposited Ni and Co metal films was systematically studied. Varying the water concentration in the precursor solutions, beneficial as well as detrimental effects of water on the metal film growth, strongly depending on the concentration of water and the β-diketonate in the precursor, were identified. For 2.5 mM Ni(acac)2 precursor solutions, addition of 0.5 vol% water improves growth of a metallic Ni film and reduces carbon contamination, while addition of 1.0 vol% water and more leads to significant oxidation of deposited Ni. By tuning the concentration of both, Ni(acac)2 and water in the precursor solution, the fraction of Ni metal and Ni oxide in the film or the film morphology can be adjusted. In the case of Co(acac)2, even smallest amounts of water promote complete oxidation of the deposited film. All deposited films were analyzed with respect to chemical composition quasi in situ by XPS, their morphology was evaluated after deposition by SEM. PMID:26658547

Surfactant mediated synthesis of bismuth selenide thin films for photoelectrochemical solar cell applications.

PubMed

Desai, Neha D; Khot, Kishorkumar V; Ghanwat, Vishvanath B; Kharade, Suvarta D; Bhosale, Popatrao N

2018-03-15

In the present report, nanostructured bismuth selenide (Bi 2 Se 3 ) thin films have been successfully deposited by using arrested precipitation technique (APT) at room temperature. The effect of three different surfactants on the optostructural, morphological, compositional and photoelectrochemical properties of Bi 2 Se 3 thin films were investigated. Optical absorption data indicates direct and allowed transition with a band gap energy varied from 1.4 eV to 1.8 eV. The X-ray diffraction pattern (XRD) revealed that Bi 2 Se 3 thin films are crystalline in nature and confirmed rhombohedral crystal structure. SEM micrographs shows morphological transition from interconnected mesh to nanospheres like and finally granular morphology. Surface topography of Bi 2 Se 3 thin films was determined by AFM. Compositional analysis of all samples was carried out by energy dispersive X-ray spectroscopy (EDS). Finally, all Bi 2 Se 3 thin films shows good PEC performance with highest photoconversion efficiency 1.47%. In order to study the stability of Bi 2 Se 3 thin films four cycles are repeated after gap of one week each. Further PEC performance of all Bi 2 Se 3 thin films are also supported by electrochemical impedance (EIS) measurement study. Copyright © 2017 Elsevier Inc. All rights reserved.

Polymer compositions, polymer films and methods and precursors for forming same

DOEpatents

Klaehn, John R; Peterson, Eric S; Orme, Christopher J

2013-09-24

Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

Large moments in bcc FexCoyMnz ternary alloy thin films

NASA Astrophysics Data System (ADS)

Snow, R. J.; Bhatkar, H.; N'Diaye, A. T.; Arenholz, E.; Idzerda, Y. U.

2018-02-01

The elemental magnetic moments and the average atomic moment of 10-20 nm thick single crystal bcc (bct) FexCoyMnz films deposited on MgO(001) have been determined as a function of a broad range of compositions. Thin film epitaxy stabilized the bcc structure for 80% of the available ternary compositional space compared to only a 23% stability region for the bulk. The films that display ferromagnetism represent 60% of the available compositional possibilities compared to 25% for the bulk. A maximum average atomic moment of 3.25 ± 0.3 μB/atom was observed for a bcc Fe9Co62Mn29 film (well above the limit of the Slater-Pauling binary alloy curve of 2.45 μB/atom). The FexCoyMnz ternary alloys that exhibit high moments can only be synthesized as ultrathin films since the bcc structure is not stable in the bulk for those compositions.

Performance of high amylose starch-composited gelatin films influenced by gelatinization and concentration.

PubMed

Wang, Wenhang; Wang, Kun; Xiao, Jingdong; Liu, Yaowei; Zhao, Yana; Liu, Anjun

2017-01-01

In order to study the impact of starch in film performance, high amylose corn starch was composited in gelatin films under different gelatinization conditions and, in high and low concentrations (10 and 50wt.%). It was found that hot water gelatinized starch (Gel-Shw) increased film mechanical strength and was dependent upon the starch concentration. The addition of an alkali component to the starch significantly enhanced the swelling of the starch granules and expedited the gelatinization process. Incorporation of starch, especially the alkalized starch (Sha), into the gelatin films decreased film solubility which improved its water resistance and water vapor permeability (WVP). Multiple techniques (DSC, TGA, FT-IR, and XRD) were used to characterize the process and results, including the crosslinking of the dissolved starch molecules and the particles formed from gelatinized starch during retrogradation process, which played an important role in improving the thermal stability of the composited gelatin films. Overall, the starch-gelatin composition provides a potential approach to improve gelatin film performance and benefit its applications in the food industry. Copyright © 2016 Elsevier B.V. All rights reserved.

Effects of lamination and coating with drying oils on tensile and barrier properties of zein films.

PubMed

Rakotonirainy, A M; Padua, G W

2001-06-01

Zein films plasticized with oleic acid have been considered potentially useful for biodegradable packaging applications. However, moisture was found to affect their tensile and gas barrier properties. We investigated the effects of two converting processes, fusion lamination and coating with drying oils, on tensile properties and gas permeability of zein films. Zein films were laminated to 4-ply sheets in a Carver press and coated with tung oil, linseed oil, or a mixture of tung and soybean oils. Tensile properties and permeability to water vapor, oxygen, and carbon dioxide were measured according to ASTM methods. Laminated films were clearer, tougher, and more flexible, and had a smoother finish than nontreated sheets. Lamination decreased O(2) and CO(2) permeability by filling in voids and pinholes in the film structure. Coating increased tensile strength and elongation and decreased water vapor permeability. Coatings acted as a composite layer preventing crack propagation and increasing film strength. They also formed a highly hydrophobic surface that prevented film wetting.

Mango kernel starch-gum composite films: Physical, mechanical and barrier properties.

PubMed

Nawab, Anjum; Alam, Feroz; Haq, Muhammad Abdul; Lutfi, Zubala; Hasnain, Abid

2017-05-01

Composite films were developed by the casting method using mango kernel starch (MKS) and guar and xanthan gums. The concentration of both gums ranged from 0% to 30% (w/w of starch; db). Mechanical properties, oxygen permeability (OP), water vapor permeability (WVP), solubility in water and color parameters of composite films were evaluated. The crystallinity and homogeneity between the starch and gums were also evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The scanning electron micrographs showed homogeneous matrix, with no signs of phase separation between the components. XRD analysis demonstrated diminished crystalline peak. Regardless of gum type the tensile strength (TS) of composite films increased with increasing gum concentration while reverse trend was noted for elongation at break (EAB) which found to be decreased with increasing gum concentration. The addition of both guar and xanthan gums increased solubility and WVP of the composite films. However, the OP was found to be lower than that of the control with both gums. Furthermore, addition of both gums led to changes in transparency and opacity of MKS films. Films containing 10% (w/w) xanthan gum showed lower values for solubility, WVP and OP, while film containing 20% guar gum showed good mechanical properties. Copyright © 2017 Elsevier B.V. All rights reserved.

Layer-by-Layer Assembled Architecture of Polyelectrolyte Multilayers and Graphene Sheets on Hollow Carbon Spheres/Sulfur Composite for High-Performance Lithium-Sulfur Batteries.

PubMed

Wu, Feng; Li, Jian; Su, Yuefeng; Wang, Jing; Yang, Wen; Li, Ning; Chen, Lai; Chen, Shi; Chen, Renjie; Bao, Liying

2016-09-14

In the present work, polyelectrolyte multilayers (PEMs) and graphene sheets are applied to sequentially coat on the surface of hollow carbon spheres/sulfur composite by a flexible layer-by-layer (LBL) self-assembly strategy. Owing to the strong electrostatic interactions between the opposite charged materials, the coating agents are very stable and the coating procedure is highly efficient. The LBL film shows prominent impact on the stability of the cathode by acting as not only a basic physical barrier, and more importantly, an ion-permselective film to block the polysulfides anions by Coulombic repulsion. Furthermore, the graphene sheets can help to stabilize the polyelectrolytes film and greatly reduce the inner resistance of the electrode by changing the transport of the electrons from a "point-to-point" mode to a more effective "plane-to-point'' mode. On the basis of the synergistic effect of the PEMs and graphene sheets, the fabricated composite electrode exhibits very stable cycling stability for over 200 cycles at 1 A g(-1), along with a high average Coulombic efficiency of 99%. With the advantages of rapid and controllable fabrication of the LBL coating film, the multifunctional architecture developed in this study should inspire the design of other lithium-sulfur cathodes with unique physical and chemical properties.

Analysis of ultraviolet exposure effects on the surface properties of epoxy/graphene nanocomposite films on Mylar substrate

NASA Astrophysics Data System (ADS)

Clausi, Marialaura; Santonicola, M. Gabriella; Schirone, Luigi; Laurenzi, Susanna

2017-05-01

In this paper, we present a study of the effects generated by exposure to UV-C radiation on nanocomposite films made of graphene nanoplatelets dispersed in an epoxy matrix. The nanocomposite films, at different nanoparticle size and concentration, were fabricated on Mylar substrate using the spin coating process. The effects of UV-C irradiation on the surface hydrophobicity and on the electrical properties of the epoxy/graphene films were investigated using contact angle measurements and electrical impedance spectroscopy, respectively. According to our results, the UV-C irradiation selectively degrades the polymer matrix of the nanocomposite films, giving rise to more conductive and hydrophobic layers due to exposure of the graphene component of the composite material. The results presented here have important implications in the design of spacecraft components and structures destined for long-term space missions.

Highly selective room temperature NO2 gas sensor based on rGO-ZnO composite

NASA Astrophysics Data System (ADS)

Jyoti, Kanaujiya, Neha; Varma, G. D.

2018-05-01

Blending metal oxide nanoparticles with graphene or its derivatives can greatly enhance gas sensing characteristics. In the present work, ZnO nanoparticles have been synthesized via reflux method. Thin films of reduced graphene oxide (rGO) and composite of rGO-ZnO have been fabricated by drop casting method for gas sensing application. The samples have been characterized by X-ray diffraction (XRD) and Field-emission scanning electron microscope (FESEM) for the structural and morphological studies respectively. Sensing measurements have been carried out for the composite film of rGO-ZnO for different concentrations of NO2 ranging from 4 to 100 ppm. Effect of increasing temperature on the sensing performance has also been studied and the rGO-ZnO composite sensor shows maximum percentage response at room temperature. The limit of detection (LOD) for rGO-ZnO composite sensor is 4ppm and it exhibits a high response of 48.4% for 40 ppm NO2 at room temperature. To check the selectivity of the composite sensor, sensor film has been exposed to 40 ppm different gases like CO, NH3, H2S and Cl2 at room temperature and the sensor respond negligibly to these gases. The present work suggests that rGO-ZnO composite material can be a better candidate for fabrication of highly selective room temperature NO2 gas sensor.

Development and characterization of carrageenan/grapefruit seed extract composite films for active packaging.

PubMed

Kanmani, Paulraj; Rhim, Jong-Whan

2014-07-01

Carrageenan-based antimicrobial films were developed by incorporation of grape fruit seed extract (GSE) at different concentration into the polymer using a solvent casing method and their physical, mechanical, and antimicrobial properties were examined. The carrageenan/GSE composite films appeared yellowish tint due to the polyphenolic compounds in the GSE. SEM analysis showed rough surface with sponge like structures on the cross section of the films. FT-IR results indicated at GSE had good compatibility with carrageenan. The amorphous structure of polymer films was not changed by the incorporation of GSE. But, the addition of GSE increased moisture content, water vapor permeability, and surface hydrophilicity of the films. The tensile strength and elastic modulus decreased with increasing content of GSE, however, the elongation at break increased significantly up to 6.6μg/mL of GSE then decreased thereafter. Thermal stability of the films was not influenced by GSE incorporation. The carrageenan/GSE composite films exhibited great antibacterial activity against food borne pathogens. These results suggest that the carrageenan-based composite films have a high potential for being used as an antimicrobial or active food packaging applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Facile one-step construction of covalently networked, self-healable, and transparent superhydrophobic composite films

NASA Astrophysics Data System (ADS)

Lee, Yujin; You, Eun-Ah; Ha, Young-Geun

2018-07-01

Despite the considerable demand for bioinspired superhydrophobic surfaces with highly transparent, self-cleaning, and self-healable properties, a facile and scalable fabrication method for multifunctional superhydrophobic films with strong chemical networks has rarely been established. Here, we report a rationally designed facile one-step construction of covalently networked, transparent, self-cleaning, and self-healable superhydrophobic films via a one-step preparation and single-reaction process of multi-components. As coating materials for achieving the one-step fabrication of multifunctional superhydrophobic films, we included two different sizes of Al2O3 nanoparticles for hierarchical micro/nano dual-scale structures and transparent films, fluoroalkylsilane for both low surface energy and covalent binding functions, and aluminum nitrate for aluminum oxide networked films. On the basis of stability tests for the robust film composition, the optimized, covalently linked superhydrophobic composite films with a high water contact angle (>160°) and low sliding angle (<1°) showed excellent thermal stability (up to 400 °C), transparency (≈80%), self-healing, self-cleaning, and waterproof abilities. Therefore, the rationally designed, covalently networked superhydrophobic composite films, fabricated via a one-step solution-based process, can be further utilized for various optical and optoelectronic applications.

Interfacial properties of aluminum/glass-fiberreinforced polypropylene sandwich composites

NASA Astrophysics Data System (ADS)

Baştürk, S. B.; Guruşçu, A.; Tanoğlu, M.

2013-07-01

Aluminum/glass-fiber-reinforced polypropylene (Al/GFPP) laminates were manufactured by using various surface pretreatment techniques. Adhesion at the composite/metal interface was achieved by a surface pretreatment of Al sheets with amino-based silane coupling agents, incorporation of a polyolefin-based adhesive film and modification with a PP-based film containing 20 wt.% of maleic-anhydride-modified polypropylene (PP-g-MA). In order to increase the effect of bonding between components of the laminates, the combination of silane treatment and the addition of the PP-based film was also investigated. The mechanical properties (shear, peel, and bending strengths) of adhesively bonded Al/GFPP laminates were examined to evaluate the effects of the surface treatments mentioned. It was revealed that the adhesion in the laminated Al/GFPP systems could be improved by the treatment of aluminum surface with an amino-based silane coupling agent. Judging from the results of peel and bending strength, with incorporation of polyolefin-based films, adhesion in the Al/GFPP laminates increased significantly. The modification of Al/GFPP interfaces with a PP-g-MA/PP layer led to the highest improvement in their adhesion properties. The combination of surface modification with silane and addition of PP-based films did not yield the high bending strength desired. This may be due to the insufficient bonding between silane groups and PP-based films.

Composition spread studies of Nd1-xLaxNiO3 combinatorial thin films

NASA Astrophysics Data System (ADS)

Suchoski, Richard; Jin, Kui; Yasui, Shintaro; Greene, Richard; Takeuchi, Ichiro

2013-03-01

Rare earth nickelates have attracted a great deal of attention in recent years due to a host of interesting features, one being a transition from paramagnetic metal to antiferromagnetic insulator through distortions from the ideal perovskite unit cell. This metal-to-insulator transition (MIT) can be manipulated by modifying variables such as temperature, rare earth ion size, oxygen content, or stress from lattice-mismatched epitaxial thin film growth. Research on this family has been extensive, though there still exists an absence of thin film studies focusing on intermediate compositions. We have fabricated epitaxial thin film composition spreads of Nd1-xLaxNiO3 grown via combinatorial PLD to investigate these transitional compositions. While our films exhibit a smooth composition progression, we observe a composition threshold where orthorhombic NdNiO3 transforms to rhombohedral LaNiO3, correlating with disappearance of the MIT, and displays a non-Vegard evolution of the film's in-plane lattice constant in HRXRD and Raman scattering data of the A1g rotational mode. This work was performed at the Center for Nanophysics and Advanced Materials (CNAM) at UMD, and supported by AFO SR MURI Grant #FA95500910603.

On the modeling of separation foils in thermoforming simulations

NASA Astrophysics Data System (ADS)

Margossian, Alexane; Bel, Sylvain; Hinterhölzl, Roland

2016-10-01

Composite forming simulations consist in modelling the forming process of composite components to anticipate the occurrence of potential flaws such as out-of-plane wrinkles and fibre re-orientation. Forming methods often consist of automated processes in which flat composite blanks are forced to comply with tool geometries. Although Finite Element forming simulations require the modelling of all stakeholders (blankholder, tooling and composite blank), consumables such as separation films are often not considered. Used in thermoforming processes, these films are placed between tooling and composite to ease part removal after forming. These films are also used to decrease tool/ply friction and thus, enhance forming quality. This work presents thermoforming simulations of pre-impregnated carbon fibre thermoplastic blanks in which separation films are modelled in the same manner as composite layers, i.e. by a layer of shell elements. The mechanical properties of such films are also characterised at the same temperature as forming occurs. The proposed approach is finally compared to the actual modelling method, in which separation films are not modelled as such but in which their influence is only considered within the friction coefficient between tooling and blank.

Optical sensor platform based on cellulose nanocrystals (CNC) - 4'-(hexyloxy)-4-biphenylcarbonitrile (HOBC) bi-phase nematic liquid crystal composite films.

PubMed

Santos, Moliria V; Tercjak, Agnieszka; Gutierrez, Junkal; Barud, Hernane S; Napoli, Mariana; Nalin, Marcelo; Ribeiro, Sidney J L

2017-07-15

The preparation of composite materials has gained tremendous attention due to the potential synergy of the combined materials. Here we fabricate novel thermal/electrical responsive photonic composite films combining cellulose nanocrystals (CNC) with a low molecular weight nematic liquid crystal (NLC), 4'-(hexyloxy)-4-biphenylcarbonitrile (HOBC). The obtained composite material combines both intense structural coloration of photonic cellulose and thermal and conductive properties of NLC. Scanning electron microscopy (SEM) results confirmed that liquid crystals coated CNC films maintain chiral nematic structure characteristic of CNC film and simultaneously, transversal cross-section scanning electron microscopy images indicated penetration of liquid crystals through the CNC layers. Investigated composite film maintain NLC optical properties being switchable as a function of temperature during heating/cooling cycles. The relationship between the morphology and thermoresponsive in the micro/nanostructured materials was investigated by using transmission optical microscopy (TOM). Conductive response of the composite films was proved by Electrostatic force microscopy (EFM) measurement. Designed thermo- and electro-responsive materials open novel simple pathway of fabrication of CNC-based materials with tunable properties. Copyright © 2017. Published by Elsevier Ltd.

Process-Induced Carbon and Sub-Layer in SiC/BN/SiC Composites: Characterization and Consequences

NASA Technical Reports Server (NTRS)

Ogbuji, L. U. J. T; Wheeler, D. R.; McCue, T. R.

2001-01-01

Following our detection of films of elemental carbon in the Hi-Nicalon TM/BN/SiC composite and its deleterious effect on oxidative durability, we have examined other SiC/BN/SiC systems. The problem is pervasive, and significant residues of free carbon are confirmed in Sylramic /BN/SiC materials. Effective techniques for routine detection and characterization of adventitious carbon in SiC/BN/SiC composites are discussed.

Organic-inorganic hybrid materials as semiconducting channels in thin-film field-effect transistors

PubMed

Kagan; Mitzi; Dimitrakopoulos

1999-10-29

Organic-inorganic hybrid materials promise both the superior carrier mobility of inorganic semiconductors and the processability of organic materials. A thin-film field-effect transistor having an organic-inorganic hybrid material as the semiconducting channel was demonstrated. Hybrids based on the perovskite structure crystallize from solution to form oriented molecular-scale composites of alternating organic and inorganic sheets. Spin-coated thin films of the semiconducting perovskite (C(6)H(5)C(2)H(4)NH(3))(2)SnI(4) form the conducting channel, with field-effect mobilities of 0.6 square centimeters per volt-second and current modulation greater than 10(4). Molecular engineering of the organic and inorganic components of the hybrids is expected to further improve device performance for low-cost thin-film transistors.

Preparation and antibacterial effect of silver hydroxyapatite/titania nanocomposite thin film on titanium

NASA Astrophysics Data System (ADS)

Mo, Anchun; Liao, Juan; Xu, Wei; Xian, Suqin; Li, Yubao; Bai, Shi

2008-11-01

The composite which contains Ag + and nanosized hydroxyapatite with TiO 2 was deposited onto titanium by dipping method. The morphology, chemical components and structures of the thin film were characterized by XRD, scanning electronic microscope (SEM) and energy dispersive X-ray analysis (EDX). Staphylococcus aureus and Escherichia coli were utilized to test the antibacterial effect. XRD results demonstrated that the films have characteristic diffraction peaks of pure HA. EDX results showed that the deposited films consisted of Ca, P, Ti, O and Ag, all of which distribute uniformly. With regard to the antibacterial effect, 98% of S. aureus and more than 99% of E. coli were killed after 24 h incubation and pictures of SEM showed obviously fewer cells on the surface with coating.

Structure and magnetic fabric of the Quetico metasedimentary rocks in the Calm Lake - Perch Lake area, near Atikokan, Northwestern Ontario

NASA Astrophysics Data System (ADS)

Sarvas, Perry

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

Fire disturbance mapping in a northern boreal forest using AVHRR/NDVI imagery: Comparing techniques of change detection and substrate correction

NASA Astrophysics Data System (ADS)

Remmel, Tarmo Kaarel

Carbon nanotubes (CNTs) with extraordinary properties and thus many potential applications have been predicted to be the best reinforcements for the next-generation multifunctional composite materials. Difficulties exist in transferring the most use of the unprecedented properties of individual CNTs to macroscopic forms of CNT assemblies. Therefore, this thesis focuses on two main goals: 1) discussing the issues that influence the performance of bulk CNT products, and 2) fabricating high-performance dry CNT films and composite films with an understanding of the fundamental structure-property relationship in these materials. Dry CNT films were fabricated by a winding process using CNT arrays with heights of 230 mum, 300 im and 360 mum. The structures of the as-produced films, as well as their mechanical and electrical properties were examined in order to find out the effects of different CNT lengths. It was found that the shorter CNTs synthesized by shorter time in the CVD furnace exhibited less structural defects and amorphous carbon, resulting in more compact packing and better nanotube alignment when made into dry films, thus, having better mechanical and electrical performance. A novel microcombing approach was developed to mitigate the CNT waviness and alignment in the dry films, and ultrahigh mechanical properties and exceptional electrical performance were obtained. This method utilized a pair of sharp surgical blades with microsized features at the blade edges as micro-combs to, for the first time, disentangle and straighten the wavy CNTs in the dry-drawn CNT sheet at single-layer level. The as-combed CNT sheet exhibited high level of nanotube alignment and straightness, reduced structural defects, and enhanced nanotube packing density. The dry CNT films produced by microcombing had a very high Young's modulus of 172 GPa, excellent tensile strength of 3.2 GPa, and unprecedented electrical conductivity of 1.8x10 5 S/m, which were records for CNT films or buckypapers. This novel technique could construct CNT films with reproducible properties, which also had the potential to be scale-up for industrial mass production. Based on the microcombing approach, dispersion issue of the long, straight, and highly aligned CNTs was investigated by adding PVA matrix into the microcombed CNT sheets. It was found although microcombing promoted the formation of agglomerated strands of the long, straight, and aligned CNTs, this was not an adverse problem in impairing the composite performance. When matrix was added, those agglomerated strands were wrapped together which maintained a more stable and better contact between nanotubes than those in the dry films. The as-produced CNT/PVA composite films exhibit an electrical conductivity of 1.84x105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which represent improvements over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, demonstrating the effectiveness and reliability of microcombing in producing high-performance CNT/polymer composite films.

The role of jet and film drops in controlling the mixing state of submicron sea spray aerosol particles

NASA Astrophysics Data System (ADS)

Wang, Xiaofei; Deane, Grant B.; Moore, Kathryn A.; Ryder, Olivia S.; Stokes, M. Dale; Beall, Charlotte M.; Collins, Douglas B.; Santander, Mitchell V.; Burrows, Susannah M.; Sultana, Camille M.; Prather, Kimberly A.

2017-07-01

The oceans represent a significant global source of atmospheric aerosols. Sea spray aerosol (SSA) particles comprise sea salts and organic species in varying proportions. In addition to size, the overall composition of SSA particles determines how effectively they can form cloud droplets and ice crystals. Thus, understanding the factors controlling SSA composition is critical to predicting aerosol impacts on clouds and climate. It is often assumed that submicrometer SSAs are mainly formed by film drops produced from bursting bubble-cap films, which become enriched with hydrophobic organic species contained within the sea surface microlayer. In contrast, jet drops formed from the base of bursting bubbles are postulated to mainly produce larger supermicrometer particles from bulk seawater, which comprises largely salts and water-soluble organic species. However, here we demonstrate that jet drops produce up to 43% of total submicrometer SSA number concentrations, and that the fraction of SSA produced by jet drops can be modulated by marine biological activity. We show that the chemical composition, organic volume fraction, and ice nucleating ability of submicrometer particles from jet drops differ from those formed from film drops. Thus, the chemical composition of a substantial fraction of submicrometer particles will not be controlled by the composition of the sea surface microlayer, a major assumption in previous studies. This finding has significant ramifications for understanding the factors controlling the mixing state of submicrometer SSA particles and must be taken into consideration when predicting SSA impacts on clouds and climate.

Formulation and characterization of novel composite semi-refined iota carrageenan-based edible film incorporating palmitic acid

NASA Astrophysics Data System (ADS)

Praseptiangga, Danar; Giovani, Sarah; Manuhara, Godras Jati; Muhammad, Dimas Rahadian Aji

2017-09-01

Novel composite films based on semi-refined iota-carrageenan (SRIC) incorporating palmitic acid (PA) were prepared by an emulsification method. Palmitic acid (PA) as hydrophobic material was incorporated into semi-refined iota-carrageenan edible films in order to improve water vapor barrier properties. Composite SRIC-based films with varying concentrations of PA (10%, 20%, and 30% w/w) were obtained by a solvent casting method. Their mechanical and barrier properties were investigated. Results showed that the incorporation of PA in films caused a significant increase (p < 0.05) in thickness as the concentration of PA increased (from 10% to 30% w/w). The mechanical properties of semi-refined iota-carrageenan were also affected by PA incorporation; increasing the concentration of PA (from 10% to 30% w/w) in films improved the tensile strength (TS). Interestingly, the TS value increased to a peak at 20% w/w PA. However, the TS value showed a decrease when PA were added at 30% w/w. Elongation-at-break (EAB) were significantly (p < 0.05) decreased when the concentration of PA in films increased (from 10% to 30% w/w). Furthermore, the incorporation of PA also affected the water vapor barrier properties of the films. Water vapor transmission rate (WVTR) of the composite semi-refined iota-carrageenan-based edible film decreased significantly (p < 0.05) as the concentration of palmitic acid increased (from 10% to 30% w/w). Composite SRIC-based edible film incorporating 30% w/w of PA presented better water vapor barrier properties as compared to other films with 10% and 20% w/w PA incorporation. Thus, formulation containing 30% w/w palmitic acid promoted films with a highly beneficial to improve water vapor barrier properties and it has the potential for food packaging applications.

LDHs/graphene film on aluminum alloys for active protection

NASA Astrophysics Data System (ADS)

Zhang, You; Yu, Peihang; Wang, Juping; Li, Yingdong; Chen, Fei; Wei, Kai; Zuo, You

2018-03-01

A layered double hydroxides (LDHs) nanocontainer film modified with graphene was fabricated on aluminum alloy via a facile two-step process. The structure, morphology and composition of LDHs/graphene film were investigated. Graphene layers were able to seal the pores of nest-like LDHs film. After the modification of graphene, the LDHs film presented hydrophobic (CA 127.8°) and enhanced anticorrosion properties. The active anticorrosion property of the composite film was attributed to the double functions of the impermeable and inert graphene layer and the active inhibitor-loaded LDHs underling film.

Variation of magnetoimpedance of electrodeposited NiFe/Cu with deposition current density

NASA Astrophysics Data System (ADS)

Mishra, A. C.; Jha, A. K.

2017-12-01

An investigation about influence of deposition current density on electrodeposited magnetic film is reported in this paper. Ferromagnetic NiFe thin films were electrodeposited on copper wires of 100 μm diameter for various electrdepostion current densities ranging from 10 to 60 mA/cm2 maintaining equal thickness in all films. The composition of deposited film varied with deposition current density and in particular, a composition of Ni79Fe21 was achieved for a current density of 20 mA/cm2. The surface microstructure of the film deposited at the current density of 20 mA/cm2 was found to have excellent smoothness. The coercivity of the film was lowest and highest value of magnetoimpedance was measured for this film. The influence of current density on film composition and hence magnetic properties was attributed to the change of deposition mechanism.

Photovoltaic Conversion Enhancement of a Carbon Quantum Dots/p-Type CuAlO2/n-Type ZnO Photoelectric Device.

PubMed

Pan, Jiaqi; Sheng, Yingzhuo; Zhang, Jingxiang; Huang, Peng; Zhang, Xin; Feng, Boxue

2015-04-22

Carbon quantum dots (C QDs)/p-type CuAlO2/n-type ZnO photoelectric bilayer film composites were prepared by a simple route, through which ZnO films were sputtered on crystal quartz substrates and CuAlO2 films were prepared by sol-gel on ZnO films and then these bilayer films were composited with C QDs on their surface. The characterization results indicated that C QDs were well combined with the surface of the CuAlO2 films. The photovoltage and photocurrent of these bilayer film composites were investigated under illumination and darkness switching, which demonstrated to be significantly enhanced compared with those of the CuAlO2/ZnO bilayer films. Through analysis, this enhancement of the photoconductivity was mainly attributed to C QDs with unique up-converted photoluminescence behavior.

Substrate spacing and thin-film yield in chemical bath deposition of semiconductor thin films

NASA Astrophysics Data System (ADS)

Arias-Carbajal Reádigos, A.; García, V. M.; Gomezdaza, O.; Campos, J.; Nair, M. T. S.; Nair, P. K.

2000-11-01

Thin-film yield in the chemical bath deposition technique is studied as a function of separation between substrates in batch production. Based on a mathematical model, it is proposed and experimentally verified in the case of CdS thin films that the film thickness reaches an asymptotic maximum with increase in substrate separation. It is shown that at a separation less than 1 mm between substrates the yield, i.e. percentage in moles of a soluble cadmium salt deposited as a thin film of CdS, can exceed 50%. This behaviour is explained on the basis of the existence of a critical layer of solution near the substrate, within which the relevant ionic species have a higher probability of interacting with the thin-film layer than of contributing to precipitate formation. The critical layer depends on the solution composition and the temperature of the bath as well as the duration of deposition. An effective value for the critical layer thickness has been defined as half the substrate separation at which 90% of the maximum film thickness for the particular bath composition, bath temperature and duration of deposition is obtained. In the case of CdS thin films studied as an example, the critical layer is found to extend from 0.5 to 2.5 mm from the substrate surface, depending on the deposition conditions.

Effects of Sorbic Acid-Chitosan Microcapsules as Antimicrobial Agent on the Properties of Ethylene Vinyl Alcohol Copolymer Film for Food Packaging.

PubMed

Hu, Shuaifeng; Yu, Jie; Wang, Zhe; Li, Li; Du, Yunfei; Wang, Liping; Liu, Yuan

2017-06-01

This paper discusses the possibility of using sorbic acid-chitosan microcapsules (S-MPs) as an antibacterial component of active ethylene vinyl alcohol copolymer (EVOH) film. S-MPs with a diameter of approximately 1 to 4 μm showed a sorbic acid loading capacity of 46.5%. Addition of S-MPs (3%, w/w) increased the tensile strength, haze, oxygen, and water vapor barrier properties, as well as reduced the elongations at break and transmittance of S-MPs-EVOH (S-MP-EVOH) film. Antibacterial tests showed that the inhibitory capacity of S-MP-EVOH film against Salmonella Enteritidis and Escherichia coli was higher than that against Listeria monocytogenes. Moreover, the antibacterial effect of sorbic acid-EVOH (S-EVOH) film was stronger than that of S-MP-EVOH film. However, S-MP-EVOH film demonstrated a longer effective time than S-EVOH film. Using the total viable counts and total volatile base nitrogen as the judgment standard, S-MP-EVOH/polyethylene terephthalate (PET) composite film could extend the shelf life of fish fillets by 4 d at 4 °C, compared with EVOH/PET film. For this reason, S-MP could be a potential antibacterial component of active films. © 2017 Institute of Food Technologists®.

Effects of bias voltage on diamond like carbon coatings deposited using titanium isopropoxide (TIPOT) and acetylene/argon mixtures onto various substrate materials.

PubMed

Said, R; Ghumman, C A A; Teodoro, M N D; Ahmed, W; Abuazza, A; Gracio, J

2010-04-01

RF-PECVD was used to prepare amorphous of carbon (DLC) onto stainless steel 316 and glass substrates. The substrates were negatively biased at between 100 V to 400 V. Thin films of DLC have been deposited using C2H2 and titanium isopropoxide (TIPOT). Argon was used to generate the plasma in the PECVD system chamber. DEKTAK 8 surface stylus profilometer was used to measure the film thickness and the deposition rate was calculated. Micro Raman spectroscopy was employed to determine the chemical structure and bonding present in the films. Composition analysis of the samples was carried out using VGTOF SIMS (IX23LS) instrument. In addition, X-ray photoelectron spectroscopy (XPS) was used to analyze the composition and chemical state of the films. The wettability of the films was examined using the optical contact angle meter (CAM200) system. Two types of liquids with different polarities were used to study changes in the surface energy. The as-grown films were in the thickness range of 200-400 nm. Raman spectroscopy results showed that the I(D)/I(G) ratio decreased when the bias voltage on the stainless steel substrates was increased. This indicates an increase in the graphitic nature of the film deposited. In contrast, on the glass substrates the I(D)/I(G) ratio increased when the bias voltage was increased indicates a greater degree of diamond like character. Chemical composition determined using XPS showed the presence of carbon and oxygen in both samples on glass and stainless steel substrates. Both coatings the contact angle of the films decreased except for 400 V which showed a slight increase. The oxygen is thought to play an important role on the polar component of a-C.

Atomic layer deposited high-k nanolaminate capacitors

NASA Astrophysics Data System (ADS)

Smith, S. W.; McAuliffe, K. G.; Conley, J. F., Jr.

2010-10-01

Al 2O 3-Ta 2O 5 nanolaminate films were prepared via atomic layer deposition (ALD) on silicon with a single overall composition and thickness, but with a varying number of Al 2O 3/Ta 2O 5 bilayers. The composition of the films was roughly 57% Al 2O 3 and 43% Ta 2O 5 and the total film thickness was held at ˜58 nm, while the number of bilayers was varied from 3 to 192 by changing the target bilayer thickness from ˜19.2 nm to ˜0.3 nm. Varying the number of bilayers was found to impact electrical properties. Although, almost all laminate films exhibited leakage, breakdown, hysteresis, and overall dielectric constant intermediate between pure Al 2O 3 and Ta 2O 5 films, laminates with few bilayers exhibited leakage current density lower than Al 2O 3 over the range of ˜3.5-4.5 MV/cm. Select samples annealed at temperatures from 400 to 900 °C were compared with as-deposited laminates. Annealing the laminate films at low temperatures improved leakage and breakdown while higher temperature anneals degraded both leakage and breakdown but improved the effective dielectric constant. A figure of merit was used to evaluate the overall ability of the various films to store charge. It was found that the few bilayer laminates were ranked higher than the many bilayer laminates as well as above both the pure Ta 2O 5 and pure Al 2O 3 films. These results indicate that even for a fixed overall composition, the electrical properties of a nanolaminate can be adjusted by varying the number of bilayers.

Gradient Structure Design of Flexible Waterborne Polyurethane Conductive Films for Ultraefficient Electromagnetic Shielding with Low Reflection Characteristic.

PubMed

Xu, Yadong; Yang, Yaqi; Yan, Ding-Xiang; Duan, Hongji; Zhao, Guizhe; Liu, Yaqing

2018-06-06

Highly efficient electromagnetic shielding materials entailing strong electromagnetic wave absorption and low reflection have become an increasing requirement for next-generation communication technologies and high-power electronic instruments. In this study, a new strategy is employed to provide flexible waterborne polyurethane composite films with an ultra-efficient electromagnetic shielding effectiveness (EMI SE) and low reflection by constructing gradient shielding layers with a magnetic ferro/ferric oxide deposited on reduced graphene oxide (rGO@Fe 3 O 4 ) and silver-coated tetraneedle-like ZnO whisker (T-ZnO/Ag) functional nanoparticles. Because of the differences in density between rGO@Fe 3 O 4 and T-ZnO/Ag, a gradient structure is automatically formed during the film formation process. The gradient distribution of rGO@Fe 3 O 4 over the whole thickness range forms an efficient electromagnetic wave absorption network that endows the film with a strong absorption ability on the top side, while a thin layer of high-density T-ZnO/Ag at the bottom constructs a highly conductive network that provides an excellent electromagnetic reflection ability for the film. This specific structure results in an "absorb-reflect-reabsorb" process when electromagnetic waves penetrate into the composite film, leading to an excellent EMI shielding performance with an extremely low reflection characteristic at a very low nanofiller content (0.8 vol % Fe 3 O 4 @rGO and 5.7 vol % T-ZnO/Ag): the EMI SE reaches 87.2 dB against the X band with a thickness of only 0.5 mm, while the shielding effectiveness of reflection (SE R ) is only 2.4 dB and the power coefficient of reflectivity ( R) is as low as 0.39. This result means that only 39% of the microwaves are reflected in the propagation process when 99.9999998% are attenuated, which is the lowest value among the reported references. This composite film with remarkable performance is suitable for application in portable and wearable smart electronics, and this method offers an effective strategy for absorption-dominated EMI shielding.

Effect of post annealing on structural, optical and dielectric properties of MgTiO3 thin films deposited by RF magnetron sputtering

NASA Astrophysics Data System (ADS)

Santhosh Kumar, T.; Bhuyan, R. K.; Pamu, D.

2013-01-01

MgTiO3 (MTO) thin films have been deposited on to quartz and platinized silicon (Pt/TiO2/SiO2/Si) substrates by RF magnetron sputtering. The metal-MTO-metal (Ag-MTO-Pt/TiO2/SiO2/Si) thin film capacitors have been fabricated at different oxygen mixing percentage (OMP). The effects of OMP and post annealing on the structural, microstructural, optical and dielectric properties of MTO films were studied. The MTO target has been synthesized by mechanochemical synthesis method. The phase purity of the sputtering target was confirmed from X-ray diffraction pattern and refined to R3bar space group with lattice parameters a = b = 5.0557(12) Å, c = 13.9003(9) Å. The chemical composition of the deposited films was confirmed from EDS spectra and all the films exhibited the composition of the sputtering target. The XRD patterns of the as-deposited films are amorphous and annealing at 700 °C for 1 h induced nanocrystallinity with the improved optical and dielectric properties. The annealed films exhibit refractive index in the range of 2.12-2.19 at 600 nm with an optical bandgap value in between 4.11 and 4.19 eV. The increase in the refractive index and bandgap upon annealing can be attributed to the improvement in packing density, crystallinity, and decrease in porosity ratio. Both the dielectric constant and tan δ decrease with the increase in frequency and were in the range of 13.7-31.11 and 0.006-0.124, respectively. The improvement in dielectric properties with the increase in OMP has been correlated to the reduction in oxygen vacancies, increase in crystallinity and grain size of the films.

X-ray photoelectron spectroscopy characterization of composite TiO 2-poly(vinylidenefluoride) films synthesised for applications in pesticide photocatalytic degradation

NASA Astrophysics Data System (ADS)

Losito, I.; Amorisco, A.; Palmisano, F.; Zambonin, P. G.

2005-02-01

X-ray photoelectron spectroscopy (XPS) was adopted for the analytical characterization of composite titanium dioxide-poly(vinylidenefluoride) (TiO 2-PVDF) films developed for applications in the photocatalytic degradation of pollutants. The composites were deposited on glass substrates by casting or spin coating from TiO 2-PVDF suspensions in dimethylformamide (DMF). XPS data on the TiO 2-PVDF surface composition were used to optimize preparation conditions (composition of the TiO 2/PVDF suspension, deposition technique) in terms of titanium dioxide surface amount and film stability. The use of spin-coating deposition and the increase of TiO 2 amount in the DMF suspensions were found to improve the titanium surface content, although high TiO 2/PVDF ratios led to film instability. PVDF-TiO 2 films were also used in preliminary photocatalytic degradation tests on isoproturon, a phenylurea herbicide, under solar UV irradiation; the results were compared to direct photolysis to evaluate the catalytic efficiency of immobilized TiO 2 and the role played by the PVDF film during the degradation process.

Effect of structural in-depth heterogeneities on electrical properties of Pb(Zr0.52Ti0.48) O3 thin films as revealed by nano-beam X-ray diffraction

NASA Astrophysics Data System (ADS)

Vaxelaire, N.; Kovacova, V.; Bernasconi, A.; Le Rhun, G.; Alvarez-Murga, M.; Vaughan, G. B. M.; Defay, E.; Gergaud, P.

2016-09-01

A direct quantification of a structural in-depth composition in the lead zirconate titanate Pb(Zr,Ti)O3 thin films of morphotropic composition has been conducted using the newly available X-ray nano-pencil beam (i.e., beam size of 100 nm × 1 μm) diffraction approach. We tested two samples with different Zr/Ti chemical gradients. Here, we demonstrate the presence of a significant microstructural gradient between the rhombohedral and tetragonal phases through PbZrxTi1-xO3 (PZT) films with a 100 nm in-depth resolution. The phase gradient extends over around 350 nm, and it is repeated through the PZT film three times, which corresponds to the number of thermal annealings. Moreover, this microstructural gradient is in agreement with the Zr/Ti chemical gradient observed by the secondary ion mass spectroscopy (SIMS). Indeed, the quantity of tetragonal phases rises in the Ti-rich zones as revealed by SIMS, and the quantity of rhombohedral phases rises in the Zr-rich zones. We also demonstrated a huge difference in the in-depth phase variation between the two tested samples. The gradient free sample still contains 4.7% of phase variation through the film and the amplified gradient contains 9.6% of phase variation through the film. Knowing that the gradient free sample shows better electric and piezoelectric coefficients, one can draw a correlation between the chemical composition, crystallographic homogeneity, and electro-mechanical properties of the film. The more close the film is to the morphotropic composition and the more it is crystallographically homogeneous, the higher the piezoelectric coefficients of the PZT are. Finally, the adequate knowledge of phase variation and its relation to the fabrication technique are crucial for the enhancement of the PZT electro-mechanical properties. Our methodology and findings open up new perspectives in establishing a relevant quantitative feedback to reach an ultimate electro-mechanical coupling in the sol-gel PZT thin films.

Pigment-cellulose nanofibril composite and its application as a separator-substrate in printed supercapacitors

NASA Astrophysics Data System (ADS)

Torvinen, Katariina; Lehtimäki, Suvi; Keränen, Janne T.; Sievänen, Jenni; Vartiainen, Jari; Hellén, Erkki; Lupo, Donald; Tuukkanen, Sampo

2015-11-01

Pigment-cellulose nanofibril (PCN) composites were manufactured in a pilot line and used as a separator-substrate in printed graphene and carbon nanotube supercapacitors. The composites consisted typically of 80% pigment and 20% cellulose nanofibrils (CNF). This composition makes them a cost-effective alternative as a substrate for printed electronics at high temperatures that only very special plastic films can nowadays stand. The properties of these substrates can be varied within a relatively large range by the selection of raw materials and their relative proportions. A semi-industrial scale pilot line was successfully used to produce smooth, flexible, and nanoporous composites, and their performance was tested in a double functional separator-substrate element in supercapacitors. The nanostructural carbon films printed on the composite worked simultaneously as high surface area active electrodes and current collectors. Low-cost supercapacitors made from environmentally friendly materials have significant potential for use in flexible, wearable, and disposable low-end products. [Figure not available: see fulltext.

Design of improved ceramic/polymeric composites

NASA Astrophysics Data System (ADS)

Seghi, Steven Monte

This thesis describes an optimized approach for fabrication of boron nitride matrix composites reinforced with carbon fibers. The boron nitride was introduced via liquid infiltration of borazine oligomer to obtain high density (rho ˜ 1.75g/cc) composites and d002 spacings of 3.35A, which afforded excellent hydrolytic stability. The friction and wear properties were explored using an inertial dynamometer for potential replacement of current C/C in aircraft brakes. One set of tested composites provided outstanding wear resistance, incurring nearly zero wear across the entire range tested. In contrast to C/C, the coefficient of friction (COF) was relatively stable with respect to energy level, varying only 0.2 to 0.3. The wear surface morphologies were examined and it was found that low volume BN composites wore by a mechanism similar to C/C. The wear rates were controlled by the formation of a friction film from the wear debris. In the case of BN composites, this film incurred wear via an abrasive and brittle fracture mechanism while C/C exhibited only abrasive wear. As the BN content increased, a film still formed from the debris but large particles of BN emerged that limited direct contact of the surfaces thus effectively eliminating abrasive wear so the underlying film wore via brittle fracture. The removed wear debris was easily reincorporated into the film, with the suspected aid of boron oxide, thus keeping the wear rates low. The last chapter deals with the design, fabrication, and evaluation of a new coupling agent for glass fiber/epoxy matrix composites. This interface consisted of a thin coating of activated carbon (ACI) with high surface area to take advantage of mechanical interlocking. Furthermore, the surface chemistry was modified to provide varying degrees of bonding to the resin. These ACI provided equivalent moduli when compared to similar composites using commercial coupling agents. Hygrothermal aging showed the basic surface chemistry ACI to be extremely resistant to mechanical property degradation. The ACI systems displayed two distinct failure modes, fiber/matrix fracture and fiber debonding, controlled by the interface strength and thus the surface chemistry. These different failure modes led to a damage evolution study via thermoelastic stress analysis.

Modification of Bacterial Cellulose Biofilms with Xylan Polyelectrolytes.

PubMed

Santos, Sara M; Carbajo, José M; Gómez, Nuria; Ladero, Miguel; Villar, Juan C

2017-11-28

The effect of the addition of two [4-butyltrimethylammonium]-xylan chloride polyelectrolytes (BTMAXs) on bacterial cellulose (BC) was evaluated. The first strategy was to add the polyelectrolytes to the culture medium together with a cell suspension of the bacterium. After one week of cultivation, the films were collected and purified. The second approach consisted of obtaining a purified and homogenized BC, to which the polyelectrolytes were added subsequently. The films were characterized in terms of tear and burst indexes, optical properties, surface free energy, static contact angle, Gurley porosity, SEM, X-ray diffraction and AFM. Although there are small differences in mechanical and optical properties between the nanocomposites and control films, the films obtained by BC synthesis in the presence of BTMAXs were remarkably less opaque, rougher, and had a much lower specular gloss. The surface free energy depends on the BTMAXs addition method. The crystallinity of the composites is lower than that of the control material, with a higher reduction of this parameter in the composites obtained by adding the BTMAXs to the culture medium. In view of these results, it can be concluded that BC-BTMAX composites are a promising new material, for example, for paper restoration.

Influence of Composition on the Thermoelectric Properties of Bi1- x Sb x Thin Films

NASA Astrophysics Data System (ADS)

Rogacheva, E. I.; Nashchekina, O. N.; Orlova, D. S.; Doroshenko, A. N.; Dresselhaus, M. S.

2017-07-01

Bi1- x Sb x solid solutions have attracted much attention as promising thermoelectric (TE) materials for cooling devices at temperatures below ˜200 K and as unique model materials for solid-state science because of a high sensitivity of their band structure to changes in composition, temperature, pressure, etc. Earlier, we revealed a non-monotonic behavior of the concentration dependences of TE properties for polycrystalline Bi1- x Sb x solid solutions and attributed these anomalies to percolation effects in the solid solution, transition to a gapless state, and to a semimetal-semiconductor transition. The goal of the present work is to find out whether the non-monotonic behavior of the concentration dependences of TE properties is observed in the thin film state as well. The objects of the study are Bi1- x Sb x thin films with thicknesses in the range d = 250-300 nm prepared by thermal evaporation of Bi1- x Sb x crystals ( x = 0-0.09) onto mica substrates. It was shown that the anomalies in the dependence of the TE properties on Bi1- x Sb x crystal composition are reproduced in thin films.

Atomic layer deposition of zirconium silicate films using zirconium tetrachloride and tetra-n-butyl orthosilicate

NASA Astrophysics Data System (ADS)

Kim, Won-Kyu; Kang, Sang-Woo; Rhee, Shi-Woo; Lee, Nae-In; Lee, Jong-Ho; Kang, Ho-Kyu

2002-11-01

Atomic layer chemical vapor deposition of zirconium silicate films with a precursor combination of ZrCl4 and tetra-n-butyl orthosilicate (TBOS) was studied for high dielectric gate insulators. The effect of deposition conditions, such as deposition temperature, pulse time for purge and precursor injection on the deposition rate per cycle, and composition of the film were studied. At 400 °C, the growth rate saturated to 1.35 Å/cycle above 500 sccm of the argon purge flow rate. The growth rate, composition ratio ((Zr/Zr+Si)), and impurity contents (carbon and chlorine) saturated with the increase of the injection time of ZrCl4 and TBOS and decreased with the increased deposition temperature from 300 to 500 °C. The growth rate, composition ratio, carbon, and chlorine contents of the Zr silicate thin films deposited at 500 °C were 1.05 Å/cycle, 0.23, 1.1 at. %, and 2.1 at. %, respectively. It appeared that by using only zirconium chloride and silicon alkoxide sources, the content of carbon and chlorine impurities could not be lowered below 1%. It was also found that the incorporation rate of metal from halide source was lower than alkoxide source.

Preparation and Characterization of Cu-Ga-Se Thin Films Synthesized by Electrodeposition: Effect of Complexing Agent and Supporting Electrolyte

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turner, John A; Deutsch, Todd G; Fernandez, A. M.

CuGaSe2 (CGS) is a semiconductor that has potential use as a photo electrode for solar water splitting. Its wide band gap and high absorption coefficient make it an ideal candidate for the top absorber in tandem structures. CGS can be synthesized by several techniques, being electrodeposition the most advantageous from a technical standpoint. Many reports show that electrodeposition of these films for producing the desired precursor atomic composition can be aided by using a complexing agent. However, the use of supporting electrolyte and the type of the electrolyte to improve the atomic composition in the films has never been reported.more » Using cyclic voltammetry, with complexing agents and deposition potentials between -0.5 and -0.9 V vs. Ag/AgCl reference electrode atomic ratios close to the ideal values ([Cu]/[Ga] = 1 and [Se]/[Cu + Ga] = 1), based on atomic composition and morphology analysis are reported in this work. From the X-ray diffraction (XRD), the as-deposited films exhibit poor crystallinity; however, the XRD patterns evidence the formation CuGaSe2 after annealing of the samples.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stiubianu, George, E-mail: george.stiubianu@icmpp.ro; Bele, Adrian; Cazacu, Maria

Highlights: • Composite ceramics nanoparticles (MCN) with zirconium dioxide and lead zirconate. • Dielectric elastomer films wDith PDMS matrix and MCN as dielectric filler. • Hydrophobic character—water resistant and good flexibility specific to siloxanes. • Increased value of dielectric constant with the content of MCN in dielectric films. • Increased energy output from uniaxial deformation of the dielectric elastomer films. - Abstract: A ceramic material consisting in a zirconium dioxide-lead zirconate mixture has been obtained by precipitation method, its composition being proved by wide angle X-ray powder diffraction and energy-dispersive X-ray spectroscopy. The average diameter of the ceramic particles rangedmore » between 50 and 100 nm, as revealed by transmission electron microscopy images. These were surface treated and used as filler for a high molecular mass polydimethylsiloxane-α,ω-diol (Mn = 450,000) prepared in laboratory, the resulted composites being further processed as films and crosslinked. A condensation procedure, unusual for polydimethylsiloxane having such high molecular mass, with a trifunctional silane was approached for the crosslinking. The effect of filler content on electrical and mechanical properties of the resulted materials was studied and it was found that the dielectric permittivity of nanocomposites increased in line with the concentration of ceramic nanoparticles.« less

Effect of silver thickness on structural, optical and morphological properties of nanocrystalline Ag/NiO thin films

NASA Astrophysics Data System (ADS)

Jalili, S.; Hajakbari, F.; Hojabri, A.

2018-03-01

Silver (Ag) nanolayers were deposited on nickel oxide (NiO) thin films by DC magnetron sputtering. The thickness of Ag layers was in range of 20-80 nm by variation of deposition time between 10 and 40 s. X-ray diffraction results showed that the crystalline properties of the Ag/NiO films improved by increasing the Ag film thickness. Also, atomic force microscopy and field emission scanning electron microscopy images demonstrated that the surface morphology of the films was highly affected by film thickness. The film thickness and the size of particles change by elevating the Ag deposition times. The composition of films was determined by Rutherford back scattering spectroscopy. The transmission of light was gradually reduced by augmentation of Ag films thickness. Furthermore; the optical band gap of the films was also calculated from the transmittance spectra.

Preparation of Self-Assembled Chitin Nanofiber-Natural Rubber Composite Sheets and Porous Materials

PubMed Central

Kawano, Akito; Yamamoto, Kazuya

2017-01-01

We previously reported the preparation of a self-assembled chitin nanofiber (CNF) film via regeneration from an ion gel with an ionic liquid, followed by sonication and filtration. Based on the finding that CNFs were redispersed in a mixture of the film with ammonia aqueous solution (aq.), in this study, CNF-natural rubber (NR) composite sheets were fabricated by mixing redispersed CNF with NR latex stabilized by ammonia, followed by drying under reduced pressure. Tensile testing of the sheets indicated the reinforcing effect of CNFs. Further, CNF-NR composite porous materials were fabricated by evaporating ammonia from the CNF-NR dispersion, followed by lyophilization. The mechanism for the formation of porous structures was evaluated. PMID:28671578

Preparation and Characterization of Extruded Composites Based on Polypropylene and Chitosan Compatibilized with Polypropylene-Graft-Maleic Anhydride.

PubMed

Carrasco-Guigón, Fernando Javier; Rodríguez-Félix, Dora Evelia; Castillo-Ortega, María Mónica; Santacruz-Ortega, Hisila C; Burruel-Ibarra, Silvia E; Encinas-Encinas, Jose Carmelo; Plascencia-Jatomea, Maribel; Herrera-Franco, Pedro Jesus; Madera-Santana, Tomas Jesus

2017-01-25

The preparation of composites of synthetic and natural polymers represent an interesting option to combine properties; in this manner, polypropylene and chitosan extruded films using a different proportion of components and polypropylene-graft-maleic anhydride (PPgMA) as compatibilizer were prepared. The effect of the content of the biopolymer in the polypropylene (PP) matrix, the addition of compatibilizer, and the particle size on the properties of the composites was analyzed using characterization by fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), tensile strength, and contact angle, finding that in general, the addition of the compatibilizer and reducing the particle size of the chitosan, favored the physicochemical and morphological properties of the films.

Photoluminescence from Au nanoparticles embedded in Au:oxide composite films

NASA Astrophysics Data System (ADS)

Liao, Hongbo; Wen, Weijia; Wong, George K.

2006-12-01

Au:oxide composite multilayer films with Au nanoparticles sandwiched by oxide layers (such as SiO2, ZnO, and TiO2) were prepared in a magnetron sputtering system. Their photoluminescence (PL) spectra were investigated by employing a micro-Raman system in which an Argon laser with a wavelength of 514 nm was used as the pumping light. Distinct PL peaks located at a wavelength range between 590 and 680 nm were observed in most of our samples, with Au particle size varying from several to hundreds of nanometers. It was found that the surface plasmon resonance (SPR) in these composites exerted a strong influence on the position of the PL peaks but had little effect on the PL intensity.

Scanning angle Raman spectroscopy: A nondestructive method for simultaneously determining mixed polymer fractional composition and film thickness

DOE PAGES

Bobbitt, Jonathan M.; Mendivelso-Pérez, Deyny; Smith, Emily A.

2016-11-03

A scanning angle (SA) Raman spectroscopy method was developed to simultaneously measure the chemical composition and thickness of waveguide mixed polymer films with varying fractional compositions. In order to test the method, six films of polystyrene-block-poly(methyl methacrylate), some mixed with poly(methyl methacrylate) homopolymer (PS-b-PMMA:PMMA), and two films of poly(2-vinylnapthalene)-block-poly(methyl methacrylate) (P2VN-b-PMMA) were prepared. The film thickness ranged from 495 to 971 nm. The chemical composition and thickness of PS-b-PMMA:PMMA films was varied by the addition of the PMMA homopolymer and annealing the films in toluene. SA Raman peak amplitude ratios (1001 cm -1 for PS, 812 cm -1 for PMMA,more » and 1388 cm -1 for P2VN) were used to calculate the refractive index of the polymer film, an input parameter in calculations of the sum square electric field (SSEF). The film thickness was determined by SSEF models of the experimental Raman amplitudes versus the incident angle of light. The average film thickness determined by the developed SA Raman spectroscopy method was within 5% of the value determined by optical profilometry. In conclusion, SA Raman spectroscopy will be useful for in situ label-free analyses of mixed polymer waveguide films.« less

Antimicrobial and in vitro wound healing properties of novel clay based bionanocomposite films.

PubMed

Mishra, R K; Ramasamy, K; Lim, S M; Ismail, M F; Majeed, A B A

2014-08-01

The present study investigates the development of methyl cellulose (MC)-sodium alginate (SA)-montmorillonite (MMT) clay based bionanocomposite films with interesting wound healing properties. The differential scanning calorimetry analysis of the composite films revealed presence of single glass transition temperature (Tg) confirming the miscible nature of the ternary blended films. The increase in MMT ratio in the composite films reduced the mobility of biopolymer chains (MC/SA) which increased the Tg of the film. Thermogravimetric analysis showed that dispersion of clay (MMT) at nano level significantly delayed the weight loss that correlated with higher thermal stability of the composite films. It was observed that the developed films were able to exhibit antimicrobial activity against four typical pathogenic bacteria found in the presence of wound. The developed films were able to significantly inhibit (10 mg/ml) the growth of Enterococcus faecium and Pseudomonas aeruginosa. In vitro scratch assay indicated potential wound closure activities of MC-2-4 bionanocomposite films at their respective highest subtoxic doses. In conclusion, these ternary bionanocomposite films were found to be promising systems for wound healing applications.

A New NIST Database for the Simulation of Electron Spectra for Surface Analysis (SESSA): Application to Angle-Resolved X-ray Photoelectron Spectroscopy of HfO2, ZrO2, HfSiO4, and ZrSiO4 Films on Silicon

NASA Astrophysics Data System (ADS)

Powell, C. J.; Smekal, W.; Werner, W. S. M.

2005-09-01

We describe a new NIST database for the Simulation of Electron Spectra for Surface Analysis (SESSA). This database provides data for the many parameters needed in quantitative Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). In addition, AES and XPS spectra can be simulated for layered samples. The simulated spectra, for layer compositions and thicknesses specified by the user, can be compared with measured spectra. The layer compositions and thicknesses can then be adjusted to find maximum consistency between simulated and measured spectra. In this way, AES and XPS can provide more detailed characterization of multilayer thin-film materials. We report on the use of SESSA for determining the thicknesses of HfO2, ZrO2, HfSiO4, and ZrSiO4 films on Si by angle-resolved XPS. Practical effective attenuation lengths (EALs) have been computed from SESSA as a function of film thickness and photoelectron emission angle (i.e., to simulate the effects of tilting the sample). These EALs have been compared with similar values obtained from the NIST Electron Effective-Attenuation-Length Database (SRD 82). Generally good agreement was found between corresponding EAL values, but there were differences for film thicknesses less than the inelastic mean free path of the photoelectrons in the overlayer film. These differences are due to a simplifying approximation in the algorithm used to compute EALs in SRD 82. SESSA, with realistic cross sections for elastic and inelastic scattering in the film and substrate materials, is believed to provide more accurate EALs than SRD 82 for thin-film thickness measurements, particularly in applications where the film and substrate have different electron-scattering properties.

A New NIST Database for the Simulation of Electron Spectra for Surface Analysis (SESSA): Application to Angle-Resolved X-ray Photoelectron Spectroscopy of HfO2, ZrO2, HfSiO4, and ZrSiO4 Films on Silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powell, C.J.; Smekal, W.; Werner, W.S.M.

2005-09-09

We describe a new NIST database for the Simulation of Electron Spectra for Surface Analysis (SESSA). This database provides data for the many parameters needed in quantitative Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). In addition, AES and XPS spectra can be simulated for layered samples. The simulated spectra, for layer compositions and thicknesses specified by the user, can be compared with measured spectra. The layer compositions and thicknesses can then be adjusted to find maximum consistency between simulated and measured spectra. In this way, AES and XPS can provide more detailed characterization of multilayer thin-film materials. Wemore » report on the use of SESSA for determining the thicknesses of HfO2, ZrO2, HfSiO4, and ZrSiO4 films on Si by angle-resolved XPS. Practical effective attenuation lengths (EALs) have been computed from SESSA as a function of film thickness and photoelectron emission angle (i.e., to simulate the effects of tilting the sample). These EALs have been compared with similar values obtained from the NIST Electron Effective-Attenuation-Length Database (SRD 82). Generally good agreement was found between corresponding EAL values, but there were differences for film thicknesses less than the inelastic mean free path of the photoelectrons in the overlayer film. These differences are due to a simplifying approximation in the algorithm used to compute EALs in SRD 82. SESSA, with realistic cross sections for elastic and inelastic scattering in the film and substrate materials, is believed to provide more accurate EALs than SRD 82 for thin-film thickness measurements, particularly in applications where the film and substrate have different electron-scattering properties.« less