Preparing and Testing a Magnetic Antimicrobial Silver Nanocomposite for Water Disinfection to Gain Experience at the Nanochemistry-Microbiology Interface

ERIC Educational Resources Information Center

Furlan, Ping Y.; Fisher, Adam J.; Melcer, Michael E.; Furlan, Alexander Y.; Warren, John B.

2017-01-01

We describe a 2 h introductory laboratory procedure that prepares a novel magnetic antimicrobial activated carbon nanocomposite in which nanoscale sized magnetite and silver particles are incorporated (MACAg). The MACAg nanocomposite has achieved the synergistic properties derived from its components and demonstrated its applicability as an…

Polymer-Particle Nanocomposites: Size and Dispersion Effects

NASA Astrophysics Data System (ADS)

Moll, Joseph

Polymer-particle nanocomposites are used in industrial processes to enhance a broad range of material properties (e.g. mechanical, optical, electrical and gas permeability properties). This dissertation will focus on explanation and quantification of mechanical property improvements upon the addition of nanoparticles to polymeric materials. Nanoparticles, as enhancers of mechanical properties, are ubiquitous in synthetic and natural materials (e.g. automobile tires, packaging, bone), however, to date, there is no thorough understanding of the mechanism of their action. In this dissertation, silica (SiO2) nanoparticles, both bare and grafted with polystyrene (PS), are studied in polymeric matrices. Several variables of interest are considered, including particle dispersion state, particle size, length and density of grafted polymer chains, and volume fraction of SiO2. Polymer grafted nanoparticles behave akin to block copolymers, and this is critically leveraged to systematically vary nanoparticle dispersion and examine its role on the mechanical reinforcement in polymer based nanocomposites in the melt state. Rheology unequivocally shows that reinforcement is maximized by the formation of a transient, but long-lived, percolating polymer-particle network with the particles serving as the network junctions. The effects of dispersion and weight fraction of filler on nanocomposite mechanical properties are also studied in a bare particle system. Due to the interest in directional properties for many different materials, different means of inducing directional ordering of particle structures are also studied. Using a combination of electron microscopy and x-ray scattering, it is shown that shearing anisotropic NP assemblies (sheets or strings) causes them to orient, one in front of the other, into macroscopic two-dimensional structures along the flow direction. In contrast, no such flow-induced ordering occurs for well dispersed NPs or spherical NP aggregates! This work

Electrochemical preparation of poly(methylene blue)/graphene nanocomposite thin films

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

Erçarıkcı, Elif; Dağcı, Kader; Topçu, Ezgi

2014-07-01

Highlights: • Poly(MB)/graphene thin films are prepared by a simple electrochemical approach. • Graphene layers in the film show a broad band in visible region of absorbance spectra. • Morphology of composite films indicates both disordered and ordered regions. • XRD reveals that nanocomposite films include rGO layers after electropolymerization process. • Chemically prepared graphene is better than electrochemically prepared graphene for electrooxidation of nitrite. - Abstract: Poly(methylene blue)/graphene nanocomposite thin films were prepared by electropolymerization of methylene blue in the presence of graphene which have been synthesized by two different methods of a chemical oxidation process and an electrochemicalmore » approach. Synthesized nanocomposite thin films were characterized by using cyclic voltammetry, UV–vis. absorption spectroscopy, powder X-ray diffraction, and scanning tunneling microscopy techniques. Electrocatalytical properties of prepared poly(methylene blue)/graphene nanocomposite films were compared toward electrochemical oxidation of nitrite. Under optimized conditions, electrocatalytical effect of nanocomposite films of chemically prepared graphene through electrochemical oxidation of nitrite was better than that of electrochemically prepared graphene.« less

Preparation and electrocatalytic activity of tungsten carbide and titania nanocomposite

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

Hu, Sujuan; Shi, Binbin; Yao, Guoxing

2011-10-15

Graphical abstract: The electrocatalytic activity of tungsten carbide and titania nanocomposite is related to the structure, crystal phase and chemical components of the nanocomposite, and is also affected by the property of electrolyte. A synergistic effect exists between tungsten carbide and titania of the composite. Highlights: {yields} Electrocatalytic activity of tungsten carbide and titania nanocomposite with core-shell structure. {yields} Activity is related to the structure, crystal phase and chemical component of the nanocomposite. {yields} The property of electrolyte affects the electrocatalytic activity. {yields} A synergistic effect exists between tungsten carbide and titania of the composite. -- Abstract: Tungsten carbide andmore » titania nanocomposite was prepared by combining a reduced-carbonized approach with a mechanochemical approach. The samples were characterized by X-ray diffraction, transmission electron microscope under scanning mode and X-ray energy dispersion spectrum. The results show that the crystal phases of the samples are composed of anatase, rutile, nonstoichiometry titanium oxide, monotungsten carbide, bitungsten carbide and nonstoichiometry tungsten carbide, and they can be controlled by adjusting the parameters of the reduced-carbonized approach; tungsten carbide particles decorate on the surface of titania support, the diameter of tungsten carbide particle is smaller than 20 nm and that of titania is around 100 nm; the chemical components of the samples are Ti, O, W and C. The electrocatalytic activity of the samples was measured by a cyclic voltammetry with three electrodes. The results indicate that the electrocatalytic activities of the samples are related to their crystal phases and the property of electrolyte in aqueous solution. A synergistic effect between titania and tungsten carbide is reported for the first time.« less

Preparation, characterizations and photocatalytic activity of a ZnO/TiO2 nanocomposite

NASA Astrophysics Data System (ADS)

Lachom, Vichuda; Poolcharuansin, Phitsanu; Laokul, Paveena

2017-03-01

Nanoparticles of TiO2, ZnO and nanocomposite ZnO/TiO2 were prepared via a co-precipitation method. The precursor powders were calcined in air at 400 and 500 °C for 2 h. Crystallite sizes of the calcined samples ranged from 11-43 nm. The XRD patterns of ZnO/TiO2 powder showed two phases of anatase and wurtzite, with no ZnTiO3 impurity phase. TEM images showed three types of particles in the ZnO/TiO2 samples: a fine particle type of TiO2 and submicron ellipsoidal and rod-like particles of ZnO. The energy gap (E g) of the calcined powders was evaluated using UV-vis absorption spectra and found to be in the range of 3.15-3.60 eV. Photodegradation efficiencies of the prepared samples in methyl orange aqueous solution were investigated under UVA irradiation. The results showed that nanocomposite ZnO/TiO2 calcined at 400 °C exhibited the highest apparent rate constant (k), and a higher capacity for methyl orange removal than TiO2 and ZnO nanoparticles.

Preparation and Characterization of Natural Rubber/Organophilic Clay Nanocomposites

NASA Astrophysics Data System (ADS)

Gonzales-Fernandes, M.; Esper, F. J.; Silva-Valenzuela, M. G.; Martín-Cortés, G. R.; Valenzuela-Diaz, F. R.; Wiebeck, H.

Natural rubber/organophilic clay nanocomposites were prepared and characterized. A brown bentonite from Paraiba's State, Brazil was modified with a sodium salt and treated with quaternary ammonium salt hexadecyltrimethyl ammonium chloride. The clay in its natural state, after cation exchange with sodium and after organophilization was characterized by XRD, IR, SEM, thermal analysis. Nanocomposite samples were prepared containing 10 resin percent of organophilic clay. The vulcanized samples were analyzed by XRD, SEM. The nanocomposites obtained showed improvement in their mechanical properties in comparison with samples without clay.

Preparation, characterization, and antibacterial activity studies of silver-loaded poly(styrene-co-acrylic acid) nanocomposites.

PubMed

Song, Cunfeng; Chang, Ying; Cheng, Ling; Xu, Yiting; Chen, Xiaoling; Zhang, Long; Zhong, Lina; Dai, Lizong

2014-03-01

A simple method for preparing a new type of stable antibacterial agent was presented. Monodisperse poly(styrene-co-acrylic acid) (PSA) nanospheres, serving as matrices, were synthesized via soap-free emulsion polymerization. Field-emission scanning electron microscopy micrographs indicated that PSA nanospheres have interesting surface microstructures and well-controlled particle size distributions. Silver-loaded poly(styrene-co-acrylic acid) (PSA/Ag-NPs) nanocomposites were prepared in situ through interfacial reduction of silver nitrate with sodium borohydride, and further characterized by transmission electron microscopy and X-ray diffraction. Their effects on antibacterial activity including inhibition zone, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bactericidal kinetics were evaluated. In the tests, PSA/Ag-NPs nanocomposites showed excellent antibacterial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli. These nanocomposites are considered to have potential application in antibacterial coatings on biomedical devices to reduce nosocomial infection rates. Copyright © 2013 Elsevier B.V. All rights reserved.

Preparation and characterization of ZnO/graphene nanocomposite for improved photovoltaic performance

NASA Astrophysics Data System (ADS)

Jayabal, P.; Gayathri, S.; Sasirekha, V.; Mayandi, J.; Ramakrishnan, V.

2014-11-01

Zinc oxide (ZnO) nanoparticles and ZnO/graphene (ZG) nanocomposite were synthesized via simple chemical route and its application as a photoanode for dye-sensitized solar cell (DSSC) was demonstrated. The prepared ZnO and ZG were structurally characterized by X-ray diffraction and micro-Raman techniques. The scanning electron micrograph of ZG revealed the spherical-shaped ZnO nanoparticles of particle size 160 nm was anchored on the two-dimensional graphene sheets. UV-Vis absorption spectroscopy showed that the ZG nanocomposite has enriched visible light absorption. The DSSCs were fabricated using the synthesized ZnO and ZG nanocomposite as photoanode and the effect of low-cost organic dyes on the photovoltaic performances of the solar cells were investigated. Comprehensive performances of ZG are better than that of ZnO-based DSSCs. The ZG DSSCs show power conversion efficiency (PCE) of 1.5 and 0.98 % for RB and EY sensitized electrodes, respectively. Moreover, the ZG dominates in many aspects due to the presence of graphene.

Polyimide Nanocomposites Prepared from High-Temperature, Reduced Charge Organoclays

NASA Technical Reports Server (NTRS)

Delozier, D. M.; Orwoll, R. A.; Cahoon, J. F.; Ladislaw, J. S.; Smith, J. G., Jr.; Connell, J. W.

2003-01-01

Montmorillonite clays modified with the dihydrochloride salt of 1,3-bis(3-aminophenoxy)benzene (APB) were used in the preparation of polyimide/organoclay hybrid films. Organoclays with varying surface charge based upon APB were prepared and examined for their dispersion behavior in the polymer matrix. High molecular weight poly(amide acid) solutions were prepared in the presence of the organoclays. Films were cast and subsequently heated to 300C to cause imidization. The resulting nanocomposite films, containing 3 wt% of organoclay, were characterized by transmission electron microscopy and X-ray diffraction. The clay's cation exchange capacity (CEC) played a key role in determining the extent of dispersion in the polyimide matrix. Considerable dispersion was observed in some of the nanocomposite films. The most effective organoclay was found to have a CEC of 0.70 meq/g. Nanocomposite films prepared with 3-8 wt% of this organoclay were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and thin-film tensile testing. High levels of clay dispersion could be achieved even at the higher clay loadings. Results from mechanical testing revealed that while the moduli of the nanocomposites increased with increasing clay loadings, both strength and elongation decreased.

Poly (γ-glutamic acid)/beta-TCP nanocomposites via in situ copolymerization: Preparation and characterization.

PubMed

Shu, Xiu-Lin; Shi, Qing-Shan; Feng, Jin; Yang, Yun-Hua; Zhou, Gang; Li, Wen-Ru

2016-07-01

A series biodegradable poly (γ-glutamic acid)/beta-tricalcium phosphate (γ-PGA/TCP) nanocomposites were prepared which were composed of poly-γ-glutamic acid polymerized in situ with β-tricalcium phosphate and physiochemically characterized as bone graft substitutes. The particle size via dynamic light scattering, the direct morphological characterization via transmission electron microscopy and field emission scanning electron microscope, which showed that γ-PGA and β-TCP were combined compactly at 80℃, and the γ-PGA/TCP nanocomposites had homogenous and nano-sized grains with narrow particle size distributions. The water uptake and retention abilities, in vitro degradation properties, cytotoxicity in the simulated medium, and protein release of these novel γ-PGA/TCP composites were investigated. Cell proliferation in composites was nearly twice than β-TCP when checked in vitro using MC3T3 cell line. We also envision the potential use of γ-PGA/TCP systems in bone growth factor or orthopedic drug delivery applications in future bone tissue engineering applications. These observations suggest that the γ-PGA/TCP are novel nanocomposites with great potential for application in the field of bone tissue engineering. © The Author(s) 2016.

Preparation and characterization of gamma irradiated Starch/PVA/ZnO nanocomposite films

NASA Astrophysics Data System (ADS)

Akhavan, Azam; Khoylou, Farah; Ataeivarjovi, Ebrahim

2017-09-01

In this study starch/PVA/ZnO nanocomposite films with antibacterial activity were prepared and modified using gamma irradiation for packaging applications. ZnO nanoparticles (NPs) were synthesized from Zn(OH)2 using hydrothermal process and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The prepared ZnO NPs were incorporated into blend films of starch and poly (vinyl alcohol) (PVA) with different concentrations from 0.1 to 1 wt% using solution casting method. The results of SEM confirmed good dispersion of ZnO NPs into the films while FTIR spectroscopy showed interactions between ZnO particles and starch/PVA blend. The nanocomposite films were irradiated at the dose range of 1-5 kGy. It was found that gamma irradiation induces a significant reduction in water absorptions of the films at the dose of 3 kGy. Different trends were observed for the tensile and elongation properties of the irradiated films. Based on the results, the bacterial growth on the films was effectively inhibited when the dosage of ZnO NPs was only 0.5 wt%.

Preparation and functionalization of graphene nanocomposites for biomedical applications

PubMed Central

Yang, Kai; Feng, Liangzhu; Hong, Hao; Cai, Weibo; Liu, Zhuang

2013-01-01

Functionalized nano-graphene– and graphene-based nanocomposites have gained tremendous attention in the area of biomedicine in recent years owing to their biocompatibility, the ease with which they can be functionalized and their properties such as thermal and electrical conductivity. potential applications for functionalized nanoparticles range from drug delivery and multimodal imaging to exploitation of the electrical properties of graphene toward the preparation of biosensing devices. this protocol covers the preparation, functionalization and bioconjugation of various graphene derivatives and nanocomposites. starting from graphite, the preparations of graphene oxide (GO), reduced GO (RGO) and magnetic GO–based nanocomposite, as well as how to functionalize them with biocompatible polymers such as polyethylene glycol (PEG), are described in detail. We also provide procedures for 125I radiolabeling of PEGylated GO and the preparation of GO-based gene carriers; other bioconjugation approaches including drug loading, antibody conjugation and fluorescent labeling are similar to those described previously and used for bioconjugation of PEGylated carbon nanotubes. We hope this article will help researchers in this field to fabricate graphene-based bioconjugates with high reproducibility for various applications in biomedicine. the sample preparation procedures take various times ranging from 1 to 2 d. PMID:24202553

Interphase and particle dispersion correlations in polymer nanocomposites

NASA Astrophysics Data System (ADS)

Senses, Erkan

Particle dispersion in polymer matrices is a major parameter governing the mechanical performance of polymer nanocomposites. Controlling particle dispersion and understanding aging of composites under large shear and temperature variations determine the processing conditions and lifetime of composites which are very important for diverse applications in biomedicine, highly reinforced materials and more importantly for the polymer composites with adaptive mechanical responses. This thesis investigates the role of interphase layers between particles and polymer matrices in two bulk systems where particle dispersion is altered upon deformation in repulsive composites, and good-dispersion of particles is retained after multiple oscillatory shearing and aging cycles in attractive composites. We demonstrate that chain desorption and re-adsorption processes in attractive composites under shear can effectively enhance the bulk microscopic mechanical properties, and long chains of adsorbed layers lead to a denser entangled interphase layer. We further designed experiments where particles are physically adsorbed with bimodal lengths of homopolymer chains to underpin the entanglement effect in interphases. Bimodal adsorbed chains are shown to improve the interfacial strength and used to modulate the elastic properties of composites without changing the particle loading, dispersion state or polymer conformation. Finally, the role of dynamic asymmetry (different mobilities in polymer blends) and chemical heterogeneity in the interphase layer are explored in systems of poly(methyl methacrylate) adsorbed silica nanoparticles dispersed in poly(ethylene oxide) matrix. Such nanocomposites are shown to exhibit unique thermal-stiffening behavior at temperatures above glass transitions of both polymers. These interesting findings suggest that the mobility of the surface-bound polymer is essential for reinforcement in polymer nanocomposites, contrary to existing glassy layer theories

Thermoplastic vulcanizate nanocomposites based on polypropylene/ethylene propylene diene terpolymer (PP/EPDM) prepared by reactive extrusion

NASA Astrophysics Data System (ADS)

Mirzadeh, Amin

For this work, different grades of polypropylene-g-maleic anhydride polymers were chosen to elucidate the effect of compatibilizer on the nanoclay dispersion level in thermoplastic phase. X-ray diffraction (XRD) patterns along with transmission electron microscopy (TEM) and scanning electron microscope (SEM) micrographs confirmed that prepared PP nanocomposites ranged from intercalated structure to a coexistence of intercalated tactoids and exfoliated layers namely “partially exfoliated” nanocomposite. Among various factors affecting the compatibilizer performance, it is shown that only the relaxation behaviour of compatibilizer correlates directly with the nanocomposites characterization results; higher relaxation times of the compatibilizer are associated with better dispersion of nanoclay. To study the co-continuity development of the nonreactive blends, EPDM and the mentioned PP nanocomposites at various compositions were melt blended using an internal mixer. Based on continuity measurements of TPEs and TPE nanocomposites for both thermoplastic and rubber phase, it is shown that the presence of nanoclay decreases the co-continuity composition range and alters its symmetrical feature. However, this effect is more pronounced in the intercalated nanocomposites than in partially exfoliated nanocomposites. It seems that better nanoclay dispersion limits the reduction of the thermoplastic phase continuity in a manner that the continuity index of the thermoplastic phase for partially exfoliated TPE nanocomposite prepared at high EPDM content (i.e. at 70 wt%) is greater than that of corresponding TPE without nanoclay. According to these results, it is possible to shift to higher EPDM content using partially exfoliated system before formation of matrix-dispersed particle structure which limits thermoplastic vulcanizate production. This should be mentioned that gamma irradiation was carried out in order to fix the EPDM morphology to estimate the continuity of PP

Decomposition and particle release of a carbon nanotube/epoxy nanocomposite at elevated temperatures

NASA Astrophysics Data System (ADS)

Schlagenhauf, Lukas; Kuo, Yu-Ying; Bahk, Yeon Kyoung; Nüesch, Frank; Wang, Jing

2015-11-01

Carbon nanotubes (CNTs) as fillers in nanocomposites have attracted significant attention, and one of the applications is to use the CNTs as flame retardants. For such nanocomposites, possible release of CNTs at elevated temperatures after decomposition of the polymer matrix poses potential health threats. We investigated the airborne particle release from a decomposing multi-walled carbon nanotube (MWCNT)/epoxy nanocomposite in order to measure a possible release of MWCNTs. An experimental set-up was established that allows decomposing the samples in a furnace by exposure to increasing temperatures at a constant heating rate and under ambient air or nitrogen atmosphere. The particle analysis was performed by aerosol measurement devices and by transmission electron microscopy (TEM) of collected particles. Further, by the application of a thermal denuder, it was also possible to measure non-volatile particles only. Characterization of the tested samples and the decomposition kinetics were determined by the usage of thermogravimetric analysis (TGA). The particle release of different samples was investigated, of a neat epoxy, nanocomposites with 0.1 and 1 wt% MWCNTs, and nanocomposites with functionalized MWCNTs. The results showed that the added MWCNTs had little effect on the decomposition kinetics of the investigated samples, but the weight of the remaining residues after decomposition was influenced significantly. The measurements with decomposition in different atmospheres showed a release of a higher number of particles at temperatures below 300 °C when air was used. Analysis of collected particles by TEM revealed that no detectable amount of MWCNTs was released, but micrometer-sized fibrous particles were collected.

Preparation of MWCNT-Fe3O4 Nanocomposites from Iron Sand Using Sonochemical Route

NASA Astrophysics Data System (ADS)

Rahmawati, R.; Melati, A.; Taufiq, A.; Sunaryono; Diantoro, M.; Yuliarto, B.; Suyatman, S.; Nugraha, N.; Kurniadi, D.

2017-05-01

The composites of multi-walled carbon nanotube (MWCNT) and magnetite (Fe3O4) nanoparticles from iron sand were successfully prepared via the sonochemical route. In this experiment, the MWCNT-Fe3O4 nanocomposites were prepared with different compositions of MWCNT (0.01%, 0.02%, and 0.04%) with the constant composition of Fe3O4 particles. The characterizations were performed by means of X-Ray Diffractometry (XRD), Fourier Transform Infra-Red (FTIR) Spectrometer and Scanning Electron Microscopy (SEM) integrated with Energy Dispersive X-Ray (EDX). The XRD data analysis showed that the Fe3O4 crystallize in spinel structure in nanometric size. Furthermore, the crystallinity of the samples tended to reduce by increasing the MWCNT compositions. The SEM images showed that Fe3O4 tend to agglomerate in nanometric size. The FTIR spectra detected the functional groups of Fe-O bonding that showed the existence of Fe2+ and Fe3+. In the composites, the Fe3O4 nanoparticles were physically mixed with the MWCNTs constructing a unique structure. The as prepared MWCNT-Fe3O4 nanocomposites have the potential for bio-applications.

Rigid polyurethane foam/cellulose whisker nanocomposites: preparation, characterization, and properties.

PubMed

Li, Yang; Ren, Hongfeng; Ragauskas, Arthur J

2011-08-01

Novel rigid polyurethane nanocomposite foams have been prepared by the polymerization of a sucrose-based polyol, a glycerol-based polyol and polymeric diphenylmethane diisocyanate in the presence of cellulose whiskers. Varying amounts of sulfuric acid hydrolyzed cellulose whiskers (0.25, 0.50, 0.75 and 1.00 wt%) prepared from a commercial fully bleached softwood kraft pulp were incorporated to investigate the effect of its dosage on the mechanical and thermal properties of polyurethane nanocomposites. Fourier transform infrared spectra of the nanocomposite foams suggested that additional hydrogen bonds were developed and crosslinking occurred between the hydroxyl groups of cellulose whiskers and isocyanate groups which increased the phase separation of soft and hard segments in the polyurethane. The closed cells of control foam and nanocomposite foams were homogeneously dispersed and the cell sizes were approximately 350 microm in diameter as observed by scanning electron microscope. A substantial improvement of mechanical properties at low whisker content (< or = 1.00 wt%) was obtained, especially the compressive strength and modulus at 1.00 wt% whiskers content which were increased by 269.7% and 210.0%, respectively. Thermal stability of the nanocomposites was also enhanced as determined by differential scanning calorimetry and thermogravimetric analysis.

Multiscale Micromechanical Modeling of Polymer/Clay Nanocomposites and the Effective Clay Particle

NASA Astrophysics Data System (ADS)

Sheng, Nuo; Boyce, Mary C.; Parks, David M.; Manovitch, Oleg; Rutledge, Gregory C.; Lee, Hojun; McKinley, Gareth H.

2003-03-01

Polymer/clay nanocomposites have been observed to exhibit enhanced mechanical properties at low weight fractions (Wp) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly dependent on particular features of the second-phase ¡°particles¡+/-; in particular, the particle volume fraction (fp), the particle aspect ratio (L/t), and the ratio of particle mechanical properties to those of the matrix. However, these important aspects of as-processed nanoclay composites have yet to be consistently and accurately defined. A multiscale modeling strategy was developed to account for the hierarchical morphology of the nanocomposite: at a lengthscale of thousands of microns, the structure is one of high aspect ratio particles within a matrix; at the lengthscale of microns, the clay particle structure is either (a) exfoliated clay sheets of nanometer level thickness or (b) stacks of parallel clay sheets separated from one another by interlayer galleries of nanometer level height. Here, quantitative structural parameters extracted from XRD patterns and TEM micrographs are used to determine geometric features of the as-processed clay ¡°particles¡+/-, including L/t and the ratio of fp to Wp. These geometric features, together with estimates of silicate lamina stiffness obtained from molecular dynamics simulations, provide a basis for modeling effective mechanical properties of the clay particle. The structure-based predictions of the macroscopic elastic modulus of the nanocomposite as a function of clay weight fraction are in excellent agreement with experimental data. The adopted methodology offers promise for study of related properties in polymer/clay nanocomposites.

Preparation and optical properties of indium tin oxide/epoxy nanocomposites with polyglycidyl methacrylate grafted nanoparticles.

PubMed

Tao, Peng; Viswanath, Anand; Schadler, Linda S; Benicewicz, Brian C; Siegel, Richard W

2011-09-01

Visibly highly transparent indium tin oxide (ITO)/epoxy nanocomposites were prepared by dispersing polyglycidyl methacrylate (PGMA) grafted ITO nanoparticles into a commercial epoxy resin. The oleic acid stabilized, highly crystalline, and near monodisperse ITO nanoparticles were synthesized via a nonaqueous synthetic route with multigram batch quantities. An azido-phosphate ligand was synthesized and used to exchange with oleic acid on the ITO surface. The azide terminal group allows for the grafting of epoxy resin compatible PGMA polymer chains via Cu(I) catalyzed alkyne-azide "click" chemistry. Transmission electron microscopy (TEM) observation shows that PGMA grafted ITO particles were homogeneously dispersed within the epoxy matrix. Optical properties of ITO/epoxy nanocomposites with different ITO concentrations were studied with an ultraviolet-visible-near-infrared (UV-vis-NIR) spectrometer. All the ITO/epoxy nanocomposites show more than 90% optical transparency in the visible light range and absorption of UV light from 300 to 400 nm. In the near-infrared region, ITO/epoxy nanocomposites demonstrate low transmittance and the infrared (IR) transmission cutoff wavelength of the composites shifts toward the lower wavelength with increased ITO concentration. The ITO/epoxy nanocomposites were applied onto both glass and plastic substrates as visibly transparent and UV/IR opaque optical coatings.

Preparation of Monodomain Liquid Crystal Elastomers and Liquid Crystal Elastomer Nanocomposites.

PubMed

Kim, Hojin; Zhu, Bohan; Chen, Huiying; Adetiba, Oluwatomiyin; Agrawal, Aditya; Ajayan, Pulickel; Jacot, Jeffrey G; Verduzco, Rafael

2016-02-06

LCEs are shape-responsive materials with fully reversible shape change and potential applications in medicine, tissue engineering, artificial muscles, and as soft robots. Here, we demonstrate the preparation of shape-responsive liquid crystal elastomers (LCEs) and LCE nanocomposites along with characterization of their shape-responsiveness, mechanical properties, and microstructure. Two types of LCEs - polysiloxane-based and epoxy-based - are synthesized, aligned, and characterized. Polysiloxane-based LCEs are prepared through two crosslinking steps, the second under an applied load, resulting in monodomain LCEs. Polysiloxane LCE nanocomposites are prepared through the addition of conductive carbon black nanoparticles, both throughout the bulk of the LCE and to the LCE surface. Epoxy-based LCEs are prepared through a reversible esterification reaction. Epoxy-based LCEs are aligned through the application of a uniaxial load at elevated (160 °C) temperatures. Aligned LCEs and LCE nanocomposites are characterized with respect to reversible strain, mechanical stiffness, and liquid crystal ordering using a combination of imaging, two-dimensional X-ray diffraction measurements, differential scanning calorimetry, and dynamic mechanical analysis. LCEs and LCE nanocomposites can be stimulated with heat and/or electrical potential to controllably generate strains in cell culture media, and we demonstrate the application of LCEs as shape-responsive substrates for cell culture using a custom-made apparatus.

Preparation and evaluation of nanocellulose-gold nanoparticle nanocomposites for SERS applications.

PubMed

Wei, Haoran; Rodriguez, Katia; Renneckar, Scott; Leng, Weinan; Vikesland, Peter J

2015-08-21

Nanocellulose is of research interest due to its extraordinary optical, thermal, and mechanical properties. The incorporation of guest nanoparticles into nanocellulose substrates enables production of novel nanocomposites with a broad range of applications. In this study, gold nanoparticle/bacterial cellulose (AuNP/BC) nanocomposites were prepared and evaluated for their applicability as surface-enhanced Raman scattering (SERS) substrates. The nanocomposites were prepared by citrate mediated in situ reduction of Au(3+) in the presence of a BC hydrogel at 303 K. Both the size and morphology of the AuNPs were functions of the HAuCl4 and citrate concentrations. At high HAuCl4 concentrations, Au nanoplates form within the nanocomposites and are responsible for high SERS enhancements. At lower HAuCl4 concentrations, uniform nanospheres form and the SERS enhancement is dependent on the nanosphere size. The time-resolved increase in the SERS signal was probed as a function of drying time with SERS 'hot-spots' primarily forming in the final minutes of nanocomposite drying. The application of the AuNP/BC nanocomposites for detection of the SERS active dyes MGITC and R6G as well as the environmental contaminant atrazine is illustrated as is its use under low and high pH conditions. The results indicate the broad applicability of this nanocomposite for analyte detection.

Preparation and characterization of graphene/CdS nanocomposites

NASA Astrophysics Data System (ADS)

Wu, Jili; Bai, Song; Shen, Xiaoping; Jiang, Lei

2010-11-01

Graphene-based nanocomposites are emerging as a new class of materials that hold promise for many applications. In this paper, we present a facile approach for the preparation of graphene/CdS nanocomposites through simple reflux processes, in which thiourea (CS(NH 2) 2) and thioacetamide (C 2H 5NS) act as a sulphide source, respectively. The samples were characterized by the X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectrum (FT-IR), ultraviolet-visible (UV-vis) spectroscopy and thermogravimetry analysis. It was shown that in the nanocomposites, the CdS nanoparticles were densely and uniformly deposited on the graphene sheets, and the sulphide source used has a great influence on the morphology, structure and property of the graphene/CdS nanocomposites. The good distribution of CdS nanoparticles on graphene sheets guarantees the efficient optoelectronic properties of graphene/CdS and would be promising for practical applications in future nanotechnology.

Preparation and properties of poly HTBN-based urethane-urea/organo reactive montmorillonite nanocomposites

NASA Astrophysics Data System (ADS)

Li, Zai-Feng; Wu, Yuan; Zhang, Fu-Tao; Cao, Yu-Yang; Wu, Shou-Peng; Wang, Ting

2012-12-01

With ultrasonic assistant mixing way, an intercalated mixture of polyol/organo reactive montmorillonite (ORMMT) was pretreated. The prepolymer composed MMT clay was prepared by reaction of polyol/ORMMT mixture with toluene diisocyanate (TDI). The resultant prepolymer reacted with extender (DMTDA) and then the polyurethane-urea/organo reactive montmorillonite (PUU/ORMMT) nanocomposites were obtained. The structure, morphology and properties of PUU/ORMMT nanocomposites were characterized by FT-IR, TEM, AFM, strain-stress machine, TGA, and dynamic mechanical analysis (DMA). The results showed that when the OMMT content is 3%, the PUU/ORMMT nanocomposities performed super mechanical properties. Because of the presence of ORMMT, both T g of the soft segment and tan δ of the PUU increased, and the decomposition temperature for the first step and the second step increased respectively. TEM images showed that the organophilic MMT particles in the PUU composite exhibit a high degree of intercalation and exfoliation.

Novel Preparation of Calcium Borate/Graphene Oxide Nanocomposites and Their Tribological Properties in Oil

NASA Astrophysics Data System (ADS)

Li, Wei; Cheng, Zhi-Lin; Liu, Zan

2017-01-01

The calcium borate/graphene oxide (CB/GO) nanocomposites have been successfully prepared by a liquid phase-based ultrasonic-assisted stripping method, which were subsequently explored as lubricant additive. The structure and morphology of the as-prepared nanocomposites were characterized by FT-IR, XRD, Raman, TEM, EDS and TGA, revealing that CB nanoparticles were uniformly loaded on GO surfaces. The nanocomposites were highly dispersed into the base oil by sand milling. The tribological properties of CB/GO nanocomposites as lubricating oil additive were investigated using a four-ball machine, and the wear scar surfaces were observed by the 3D Laser Scanning Microscope. The results indicated that CB/GO nanocomposites were of excellent antifriction, antiwear ability and load-carrying capacity.

Preparation and Characterization of Polyhydroxybutyrate/Polycaprolactone Nanocomposites

PubMed Central

Liau, Cha Ping; Bin Ahmad, Mansor; Shameli, Kamyar; Yunus, Wan Md Zin Wan

2014-01-01

Polyhydroxybutyrate (PHB)/polycaprolactone (PCL)/stearate Mg-Al layered double hydroxide (LDH) nanocomposites were prepared via solution casting intercalation method. Coprecipitation method was used to prepare the anionic clay Mg-Al LDH from nitrate salt solution. Modification of nitrate anions by stearate anions between the LDH layers via ion exchange reaction. FTIR spectra showed the presence of carboxylic acid (COOH) group which indicates that stearate anions were successfully intercalated into the Mg-Al LDH. The formation of nanocomposites only involves physical interaction as there are no new functional groups or new bonding formed. X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that the mixtures of nanocomposites are intercalated and exfoliated types. XRD results showed increasing of basal spacing from 8.66 to 32.97 Å in modified stearate Mg-Al LDH, and TEM results revealed that the stearate Mg-Al LDH layers are homogeneously distributed in the PHB/PCL polymer blends matrix. Enhancement in 300% elongation at break and 66% tensile strength in the presence of 1.0 wt % of the stearate Mg-Al LDH as compare with PHB/PCL blends. Scanning electron microscopy (SEM) proved that clay improves compatibility between polymer matrix and the best ratio 80PHB/20PCL/1stearate Mg-Al LDH surface is well dispersed and stretched before it breaks. PMID:24600329

Millable polyurethane/organoclay nanocomposites: preparation, characterization, and properties.

PubMed

Siliani, M; López-Manchado, M A; Valentín, J L; Arroyo, M; Marcos, A; Khayet, M; Villaluenga, J P G

2007-02-01

Novel millable polyurethane (PU)/organoclay nanocomposites have been successfully prepared by conventional transformation techniques. One natural (C6A) and two organically modified (C15A and C30B) montmorillonites have been used as clays for preparing PU nanocomposites. The optimum dispersion of nanofiller at a nanometer scale in PU matrix was confirmed by X-ray diffraction patterns and transmission electron microscopy. A substantial improvement of the PU properties by addition of only a small amount of organoclay was observed. It is worthy to note that the organoclays show a different interfacial interaction with the PU matrix, which was reflected in different macroscopic properties. Thus, C30B organoclay seems to react with PU chains to form covalent bonds, while C15A only interacts physically with PU chains. Mechanical and barrier properties are analyzed.

Dichlorobenzene: an effective solvent for epoxy/graphene nanocomposites preparation

PubMed Central

Saharudin, Mohd Shahneel; Vo, Thuc; Inam, Fawad

2017-01-01

It is generally recognized that dimethylformamide (DMF) and ethanol are good media to uniformly disperse graphene, and therefore have been used widely in the preparation of epoxy/graphene nanocomposites. However, as a solvent to disperse graphene, dichlorobenzene (DCB) has not been fully realized by the polymer community. Owing to high values of the dispersion component (δd) of the Hildebrand solubility parameter, DCB is considered as a suitable solvent for homogeneous graphene dispersion. Therefore, epoxy/graphene nanocomposites have been prepared for the first time with DCB as a dispersant; DMF and ethanol have been chosen as the reference. The colloidal stability, mechanical properties, thermogravimetric analysis, dynamic mechanical analysis and scanning electron microscopic images of nanocomposites have been obtained. The results show that with the use of DCB, the tensile strength of graphene has been improved from 64.46 to 69.32 MPa, and its flexural strength has been increased from 97.17 to 104.77 MPa. DCB is found to be more effective than DMF and ethanol for making stable and homogeneous graphene dispersion and composites. PMID:29134080

Dichlorobenzene: an effective solvent for epoxy/graphene nanocomposites preparation.

PubMed

Wei, Jiacheng; Saharudin, Mohd Shahneel; Vo, Thuc; Inam, Fawad

2017-10-01

It is generally recognized that dimethylformamide (DMF) and ethanol are good media to uniformly disperse graphene, and therefore have been used widely in the preparation of epoxy/graphene nanocomposites. However, as a solvent to disperse graphene, dichlorobenzene (DCB) has not been fully realized by the polymer community. Owing to high values of the dispersion component ( δ d ) of the Hildebrand solubility parameter, DCB is considered as a suitable solvent for homogeneous graphene dispersion. Therefore, epoxy/graphene nanocomposites have been prepared for the first time with DCB as a dispersant; DMF and ethanol have been chosen as the reference. The colloidal stability, mechanical properties, thermogravimetric analysis, dynamic mechanical analysis and scanning electron microscopic images of nanocomposites have been obtained. The results show that with the use of DCB, the tensile strength of graphene has been improved from 64.46 to 69.32 MPa, and its flexural strength has been increased from 97.17 to 104.77 MPa. DCB is found to be more effective than DMF and ethanol for making stable and homogeneous graphene dispersion and composites.

Preparation and characterization of polyaniline-cadmium sulfide nanocomposite for gas sensor application

NASA Astrophysics Data System (ADS)

Al-Jawad, Selma M. H.; Rafic, Sewench N.; Muhsen, Mustafa M.

2017-09-01

Polyaniline (PANI) was prepared by chemical oxidative polymerization of aniline monomers as emeraldine salt form. By the same method, polyaniline-cadmium sulfide nanocomposites were synthesized in the presence of different percentages (10-50 wt.%) of cadmium sulfide (CdS) which was prepared by using sol-gel method. The optical band gap was decrease with increasing of CdS concentration, that is obtained from UV-VIS measurements. From SEM and AFM, there is uniform distribution for cadmium sulfide nanoparticles in the PANI matrix. The electrical measurements of nanocomposites exhibit the effect of crystallite size and the high resistivity of CdS on the resistivity of nanocomposites. Emeraldine salt PANI, CdS and PANI-CdS nanocomposites were investigated as gas sensors. From this investigation, the sensitivity of PANI-CdS for NO2 gas increase with the increasing of operation temperature and the optimum sensitivity was obtained at 200∘C. The sensitivity of nanocomposites at best temperature (200∘C) was increased and faster response time with the increasing of CdS contents.

Nanocomposites prepared from acrylonitrile butadiene rubber and organically modified montmorillonite with vinyl groups

NASA Astrophysics Data System (ADS)

Han, Mijeong; Kim, Hoonjung; Kim, Eunkyoung

2006-01-01

Nanocomposites were prepared from acrylonitrile-butadiene rubber (NBR), vinyl groups containing organically modified montmorillonite and additives, such as zinc oxide, stearic acid, and sulfur. The organically modified montmorillonites used in these nanocomposites were prepared by ion exchange reactions of N,N'-dimethylalkyl-(p-vinylbenzyl)-ammonium chlorides (DAVBAs, alkyl = octyl, dodecyl, and octadecyl) with sodium montmorillonite (Na+-MMT). NBR nanocomposites were obtained by controlling both the mixing and vulcanization conditions, by using a Brabender mixer and hot-press process. X-ray diffraction (XRD) analysis shows that, depending on the amount of montmorillonite that is added, both exfoliated and intercalated nanocomposite structures are formed. The NBR/DAVBA-MMT nanocomposites exhibit much higher mechanical properties (e.g., tensile strength, Young's modulus, 300% modulus, and hardness) as well as gas barrier properties as compared to NBR Na+-MMT or NBR composites generated from modified montmorillonites without vinyl groups. Consistent with the results of XRD, transmission electron microscopy (TEM) reveals that the intercalation and exfoliation structures of the nanocomposites coexist and that the DAVBA-MMT layers are well dispersed in NBR.

Preparation and Various Characteristics of Epoxy/Alumina Nanocomposites

NASA Astrophysics Data System (ADS)

Kozako, Masahiro; Ohki, Yoshimichi; Kohtoh, Masanori; Okabe, Shigemitsu; Tanaka, Toshikatsu

Epoxy/ alumina nanocomposites were newly prepared by dispersing 3, 5, 7, and 10 weight (wt) % boehmite alumina nanofillers in a bisphenol-A epoxy resin using a special two-stage direct mixing method. It was confirmed by scanning electron microscopy imaging that the nanofillers were homogeneously dispersed in the epoxy matrix. Dielectric, mechanical, and thermal properties were investigated. It was elucidated that nanofillers affects various characteristics of epoxy resins, when they are nanostructrued. Such nano-effects we obtained are summarized as follows. Partial discharge resistance increases as the filler content increases; e.g. 7 wt% nanofiller content creates a 60 % decrease in depth of PD-caused erosion. Weibull analysis shows that short-time electrical treeing breakdown time is prolonged to 265 % by 5 wt% addition of nanofillers. But there was more data scatter in nanocomposites than in pure epoxy. Permittivity tends to increase from 3.7 to 4.0 by 5 wt% nanofiller addition as opposed to what was newly found in the recent past. Glass transition temperature remains unchanged as 109 °C. Mechanical properties such as flexural strength and flexural modulus increase; e.g. flexural strength and flexural modulus are improved by 5 % and 8 % with 5 wt% content, respectively. Excess addition causes a reverse effect. It is concluded from permittivity and glass transition temperature characteristics that interfacial bonding seems to be more or less weak in the nanocomposite specimens prepared this time, even though mechanical strengths increase. There is a possibility that the nanocomposites specimens will be improved in interfacial quality.

Carbon Nanotubes Released from an Epoxy-Based Nanocomposite: Quantification and Particle Toxicity.

PubMed

Schlagenhauf, Lukas; Buerki-Thurnherr, Tina; Kuo, Yu-Ying; Wichser, Adrian; Nüesch, Frank; Wick, Peter; Wang, Jing

2015-09-01

Studies combining both the quantification of free nanoparticle release and the toxicological investigations of the released particles from actual nanoproducts in a real-life exposure scenario are urgently needed, yet very rare. Here, a new measurement method was established to quantify the amount of free-standing and protruding multiwalled carbon nanotubes (MWCNTs) in the respirable fraction of particles abraded from a MWCNT-epoxy nanocomposite. The quantification approach involves the prelabeling of MWCNTs with lead ions, nanocomposite production, abrasion and collection of the inhalable particle fraction, and quantification of free-standing and protruding MWCNTs by measuring the concentration of released lead ions. In vitro toxicity studies for genotoxicity, reactive oxygen species formation, and cell viability were performed using A549 human alveolar epithelial cells and THP-1 monocyte-derived macrophages. The quantification experiment revealed that in the respirable fraction of the abraded particles, approximately 4000 ppm of the MWCNTs were released as exposed MWCNTs (which could contact lung cells upon inhalation) and approximately 40 ppm as free-standing MWCNTs in the worst-case scenario. The release of exposed MWCNTs was lower for nanocomposites containing agglomerated MWCNTs. The toxicity tests revealed that the abraded particles did not induce any acute cytotoxic effects.

New poly(butylene succinate)/layered silicate nanocomposites: preparation and mechanical properties.

PubMed

Ray, Suprakas Sinha; Okamoto, Kazuaki; Maiti, Pralay; Okamoto, Masami

2002-04-01

New poly(butylene succinate) (PBS)/layered silicate nanocomposites have been successfully prepared by simple melt extrusion of PBS and octadecylammonium modified montmorillonite (C18-mmt) at 150 degrees C. The d-spacing of both C18-mmt and intercalated nanocomposites was investigated by wide-angle X-ray diffraction analysis. Bright-field transmission electron microscopic study showed several stacked silicate layers with random orientation in the PBS matrix. The intercalated nanocomposites exhibited remarkable improvement of mechanical properties in both solid and melt states as compared with that of PBS matrix without clay.

Preparation process and properties of exfoliated graphite nanoplatelets filled Bisphthalonitrile nanocomposites

NASA Astrophysics Data System (ADS)

Lei, Yajie; Hu, Guo-Hua; Zhao, Rui; Guo, Heng; Zhao, Xin; Liu, Xiaobo

2012-11-01

Exfoliated graphite nanoplatelets (xGnP) filled 4,4'-Bis (3,4-dicyanophenoxy) biphenyl (BPh) nanocomposites were prepared by a resin transfer molding process. The rheological behavior of the BPh pre-polymer, and the morphology and electrical, mechanical and thermal properties of the xGnP/BPh nanocomposites were systematically investigated. The results showed that the xGnP/BPh pre-polymer possessed a higher complex viscosity and storage modulus than the pure BPh and that the xGnP could significantly enhance the mechanical and electrical properties of the resulted nanocomposites. The electrical percolation threshold of the xGnP/BPh nanocomposites was between 5 and 10 wt% xGnP. The flexural strength and modulus of the xGnP/BPh nanocomposites with 10 wt% xGnP exhibited maximum values and their thermal stabilities were greatly improved. Those novel xGnP/BPh nanocomposites could have advanced applications in areas like aerospace and military industry.

Biodegradable Polycaprolactone-Titania Nanocomposites: Preparation, Characterization and Antimicrobial Properties

PubMed Central

Muñoz-Bonilla, Alexandra; Cerrada, María L.; Fernández-García, Marta; Kubacka, Anna; Ferrer, Manuel; Fernández-García, Marcos

2013-01-01

Nanocomposites obtained from the incorporation of synthesized TiO2 nanoparticles (≈10 nm average primary particle size) in different amounts, ranging from 0.5 to 5 wt.%, into a biodegradable polycaprolactone matrix are achieved via a straightforward and commercial melting processing. The resulting nanocomposites have been structurally and thermally characterized by transmission electron microscopy (TEM), wide/small angle X-ray diffraction (WAXS/SAXS, respectively) and differential scanning calorimetry (DSC). TEM evaluation provides evidence of an excellent nanometric dispersion of the oxide component in the polymeric matrix, with aggregates having an average size well below 100 nm. Presence of these TiO2 nanoparticles induces a nucleant effect during polymer crystallization. Moreover, the antimicrobial activity of nanocomposites has been tested using both UV and visible light against Gram-negative Escherichia coli bacteria and Gram-positive Staphylococcus aureus. The bactericidal behavior has been explained through the analysis of the material optical properties, with a key role played by the creation of new electronic states within the polymer-based nanocomposites. PMID:23629663

Ferromagnetic nanocomposites

NASA Astrophysics Data System (ADS)

Mazaleyrat, F.; Varga, L. K.

2000-06-01

A survey of magnetic nanocomposites applicable in high-frequency signal and power electronics is given. First, the preparation and properties of ribbon and powder cores from the nanocrystalline "bulk" alloys (Finemet and Nanoperm) is reviewed. A technology is presented to apply continuously a large stress during the annealing and winding of the rapidly quenched ribbons in order to induce uniaxial anisotropy in it. The obtained toroidal cores with flat hysteresis curve are applicable up to 1 MHz with considerable permeability (˜250). The powder cores prepared from ground Finemet with powder size of 30-400 μm are applicable up to 1 MHz and in some cases up to 10 MHz for smaller powder sizes with low permeability (˜10). Finally, the most common methods used for the preparation of metallic nano-particle s are presented. Presently, the compacts prepared from nano-size (40-80 nm) iron powders do not show the expected behavior. It is anticipated that the iron-based ferromagnetic nanocomposites should replace partly the ferrite-type materials in the forthcoming years.

Preparation and Properties of Nanocomposites Prepared From Shortened, Functionalized Single-Walled Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Smith, J. G., Jr.; Delozier, D. M.; Watson, K. A.; Connell, J. W.; Yu, Aiping; Haddon, R. C.; Bekyarova, E.

2006-01-01

As part of a continuing materials development activity, low color space environmentally stable polymeric materials that possess sufficient electrical conductivity for electrostatic charge dissipation (ESD) have been investigated. One method of incorporating sufficient electrical conductivity for ESD without detrimental effects on other polymer properties of interest (i.e., optical and thermo-optical) is through the incorporation of single-walled carbon nanotubes (SWNTs). However, SWNTs are difficult to fully disperse in the polymer matrix. One means of improving dispersion is by shortening and functionalizing SWNTs. While this improves dispersion, other properties (i.e., electrical) of the SWNTs can be affected which can in turn alter the final nanocomposite properties. Additionally, functionalization of the polymer matrix can also influence nanocomposite properties obtained from shortened, functionalized SWNTs. The preparation and characterization of nanocomposites fabricated from a polyimide, both functionalized and unfunctionalized, and shortened, functionalized SWNTs will be presented.

Silver/poly(vinyl alcohol) nanocomposite film prepared using water in oil microemulsion for antibacterial applications.

PubMed

Fatema, Ummul K; Rahman, M Muhibur; Islam, M Rakibul; Mollah, M Yousuf A; Susan, Md Abu Bin Hasan

2018-03-15

Water in oil microemulsion (w/o) is a simple preparative route for nanoparticles where water droplets (dispersed in continuous oil medium and stabilized by surfactants and cosurfactants) act as nanoreactors to carry out chemical reactions. If polymeric matrix is incorporated inside the core of the microemulsions, it should prevent the agglomeration of nanoparticles after separation from microemulsions. Thus polymer nanocomposite films prepared from w/o microemulsions are expected to give narrow and homogeneous size distribution of nanoparticles throughout the polymer host. Silver/poly(vinyl alcohol) (Ag/PVA) nanocomposite film was successfully prepared, for the first time, using Triton X-100 (TX-100)/1-butanol/cyclohexane/water microemulsion. Reduction of the metal salt was carried out in the core of w/o microemulsion droplets containing PVA polymeric matrix. After separation from the microemulsion, Ag/PVA nanocomposite film was then prepared by solution casting method. The antibacterial activity of the nanocomposites was tested against Gram-negative, Escherichia coli and Gram-positive, Staphylococcus aureus by agar diffusion method. Ag nanoparticles with an average diameter of 105 nm could be synthesized using PVA, whereas in the absence of PVA the nanoparticles agglomerated. The distribution of Ag nanoparticles on PVA surface of the nanocomposite film prepared using microemulsion was uniform, whereas the film prepared through in situ generation of Ag nanoparticles by chemical reduction process on PVA host showed non-uniform, coagulated, bunches of Ag nanoparticles. The film synthesized using microemulsion exhibited enhanced antibacterial efficacy compared to that prepared through in situ synthesis under the same test condition. Copyright © 2017 Elsevier Inc. All rights reserved.

A study of preparation techniques and properties of bulk nanocomposites based on aqueous albumin dispersion

NASA Astrophysics Data System (ADS)

Gerasimenko, A. Yu.; Dedkova, A. A.; Ichkitidze, L. P.; Podgaetskii, V. M.; Selishchev, S. V.

2013-08-01

Bulk nanocomposites prepared from an aqueous albumin dispersion with carbon nanotubes by removing the liquid component from the dispersion have been investigated. The composites were obtained by thermostating and exposure to LED and IR diode laser radiation. The nanocomposites obtained under laser irradiation retain their shape and properties for several years, in contrast to the composites fabricated in different ways (which decompose into small fragments immediately after preparation). The low density of the composites under study (˜1200 kg/m3), which is close to the density of water, is due to their high porosity. The hardness of stable nanocomposites (˜300 MPa) was found to be at the same level as the hardness of polymethylmethacrylate, aluminum, and iron and close to the hardness of human bone tissue. The cluster quasiordering of the inner structure of nanocomposites revealed by atomic force microscopy indicates the possibility of forming a bulk nanotube framework in them, which can be caused by the effect of the electric field of laser radiation and ensure their stability and hardness. The presence of a framework in nanocomposites provides conditions for self-assembly of biological tissues and makes it possible to apply laser-prepared nanocomposites as a component of surgical implants.

Small Particle Driven Chain Disentanglements in Polymer Nanocomposites

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

Senses, Erkan; Ansar, Siyam M.; Kitchens, Christopher L.

2017-04-01

Using neutron spin-echo spectroscopy, X-ray photon correlation spectroscopy and bulk rheology, we studied the effect of particle size on the single chain dynamics, particle mobility, and bulk viscosity in athermal polyethylene oxide-gold nanoparticle composites. The results reveal an ≈ 25 % increase in the reptation tube diameter with addition of nanoparticles smaller than the entanglement mesh size (≈ 5 nm), at a volume fraction of 20 %. The tube diameter remains unchanged in the composite with larger (20 nm) nanoparticles at the same loading. In both cases, the Rouse dynamics is insensitive to particle size. These results provide a directmore » experimental observation of particle size driven disentanglements that can cause non-Einstein-like viscosity trends often observed in polymer nanocomposites.« less

Preparation and electromagnetic wave absorption of RGO/Cu nanocomposite

NASA Astrophysics Data System (ADS)

Zhang, Hui; Tian, Xingyou; Zhang, Xian; Li, Shikuo; Shen, Yuhua; Xie, Anjian

2017-09-01

We use a facile pyrolysis method to prepare reduced graphene oxide and copper nanocomposite (RGO/Cu) based on it. The product shows an outstanding wave absorption properties. The maximum reflection loss is up to-50.7 dB at 3.8 GHz. The reflection loss of-10 dB (90% power absorption) corresponds to a bandwidth of 11.2 GHz (3.4-14.6 GHz range) for the layer thickness of 2-5 mm. Therefore, it is suggested that the RGO/Cu nanocomposite is also a new kind of lightweight and high-performance EM wave absorbing material.

Preparation of polypropylene/Mg–Al layered double hydroxides nanocomposites through wet pan-milling: non-isothermal crystallization behaviour

PubMed Central

Zheng, Yilei

2018-01-01

Differential scanning calorimeter was used to extensively investigate the non-isothermal crystallization of polypropylene (PP)/layered double hydroxides (LDHs) nanocomposites prepared through wet solid-state shear milling. The corresponding crystallization kinetics was further investigated by using Ozawa, modified Avrami and combined Avrami–Ozawa method, respectively. The results showed that the Ozawa method could not well describe the crystallization kinetics of pure PP and its nanocomposites. Comparatively, the modified Avrami method as well as the combined Avrami–Ozawa method gives the satisfactory results. Under the effect of pan-milling, the produced LDH nano intercalated/exfoliated particles exhibit the inhibitive effect on the PP nucleation but more remarkable promotion effect on the spherulite growth, leading to enhancement in the overall crystallization rate. This is reflected in increase of the calculated fold surface free energy σe and also the supercooling degree ΔT required for crystallization nucleation. In addition, the polarized optical microscopy observation also verifies the higher spherulite growth rate of PP/LDHs nanocomposites than that of pure PP. PMID:29410819

Preparation and Characterization of Polyimide/Organoclay Nanocomposites

NASA Technical Reports Server (NTRS)

Delozier, D. M.; Orwoll, R. A.; Cahoon, J. F.; Johnston, N. J.; Smith, J. G., Jr.; Connell, J. W.

2002-01-01

Organically modified montmorrrillonite clay, containing a long chain aliphatic quarternary ammonium cation, was used to prepare polyimide/organoclay hybrids. Several approaches were examined in an attempt to achieve fully exfoliated nanocomposites. These included simple mixing of the clay in a pre-made high molecular weight poly(amide acid) solution; simple mixing followed by sonication of the organoclay/poly(amide acid) solutions; and the preparation of high molecular weight poly(amide acid)s in the presence of the organoclay dispersed in N-methyl-2-pyrrolidinone (NMP). The best results were obtained using the in-situ polymerization approach. The resulting nanocomposite films (both amide acid and imide), containing 3-8% by weight of organoclay, were characterized by differential scanning calorimetry (DSC), dynamic thermogravimetric analysis (TGA), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thin film tensile properties. A significant degree of dispersion was observed in the nanocomposite films of the amide acid and the imide. After thermal treatment of amide acid films to effect imidization, in both air and nitrogen, the films were visually darker than control films without clay and the level of clay dispersion appeared to have decreased. In the latter case, the separation between the layers of the clay decreased to a spacing less than that present in the original organoclay. These observations suggest that thermal degradation of the aliphatic quarternary ammonium cation occurred likely during thermal treatment to effect imidization and solvent removal. These thermal degradation effects were less pronounced when thermal treatment was performed under nitrogen. The polyimide/organoclay hybrid films exhibited higher room temperature tensile moduli and lower strength and elongation to break than the control films.

A simple route to synthesize conductive stimuli-responsive polypyrrole nanocomposite hydrogel particles with strong magnetic properties and their performance for removal of hexavalent chromium ions from aqueous solution

NASA Astrophysics Data System (ADS)

Ahmad, Hasan; Rahman, Mohammad Mostafizar; Ali, Mohammad Azgar; Minami, Hideto; Tauer, Klaus; Gafur, Mohammad Abdul; Rahman, Mohammad Mahbubor

2016-08-01

A combination of maghemite polypyrrole (PPy/γ-Fe2O3) and stimuli-responsive properties in the same hydrogel microspheres is expected to enhance their application potential in various fields such as tissue engineering, regenerative medicine, biosensors, biomedical applications and removal of heavy metals from waste water, catalysis etc. In this investigation a simple two step process is used to prepare conductive stimuli-responsive polypyrrole (PPy) composite hydrogel particles with strong magnetic properties. Poly(styrene-methacrylic acid-N-isopropylacrylamide-polyethelene glycol methacrylate) or P(S-NIPAM-MAA-PEGMA) hydrogel seed particles are first prepared by soap-free precipitation copolymerization. The copolymer hydrogel particles exhibited both temperature- and pH-responsive volume phase transition. Conductive P(S-NIPAM-MAA-PEGMA)/PPy/γ-Fe2O3 nanocomposite hydrogel particles are then prepared by seeded chemical oxidative polymerization of pyrrole in the presence of P(S-NIPAM-MAA-PEGMA) hydrogel seed particles using FeCl3 as a oxidant and p-toluene sulfonic acid (p-TSA) as a dopant. In the reaction system FeCl3 functioned as a source of Fe(III) for the formation of γ-Fe2O3. This reaction also requires the initial presence of Fe(II) provided by the addition of FeCl2. The size and size distribution, surface structure, and morphology of the prepared conductive composite hydrogel particles are confirmed by FTIR, electron micrographs, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and UV-visible spectroscopy. The performance of nanocomposite hydrogel particles has been evaluated for the removal of hexavalent chromium (Cr) ions from water.

Bulk superhard B-C-N nanocomposite compact and method for preparing thereof

DOEpatents

Zhao, Yusheng; He, Duanwei

2004-07-06

Bulk, superhard, B-C-N nanocomposite compact and method for preparing thereof. The bulk, superhard, nanocomposite compact is a well-sintered compact and includes nanocrystalline grains of at least one high-pressure phase of B-C-N surrounded by amorphous diamond-like carbon grain boundaries. The bulk compact has a Vicker's hardness of about 41-68 GPa. It is prepared by ball milling a mixture of graphite and hexagonal boron nitride, encapsulating the ball-milled mixture, and sintering the encapsulated ball-milled mixture at a pressure of about 5-25 GPa and at a temperature of about 1000-2500 K.

Carbon nanotube network evolution during deformation of PVDF-MWNT nanocomposites

NASA Astrophysics Data System (ADS)

Rizvi, Reza; Naguib, Hani E.

2013-04-01

The emergence of novel electronic systems and their requirements have necessitated the evolution of new material classes. The traditional electronic semiconductors and components are shifting from silicon based substrates to polymers and other organic compounds. Sensor components are no exceptions, where compliant polymeric materials offer the possibility of flexible electronics. This paper examines the fabrication and characterization of piezoresistive nanocomposites for pressure sensing applications. The matrix material employed was Polyvinylidene Fluoride (PVDF). The PVDF phase was reinforced with conductive particles, in order to form a conductive filler network throughout the nanocomposite. Multiwall carbon nanotubes (MWNT) were selected as conductive particles to form the networks. The composites were prepared by melt mixing the PVDF and conductive particles in compositions ranging from 0.25 to 10 wt% conductive particle in PVDF. The dielectric permittivity and electrical conductivity of the composites was characterized and the electrical percolation behavior of PVDF nanocomposites fitted to the statistical percolation model. Scanning electron was employed to understand the morphology of the filler networks in the PVDF nanocomposites. Quasi-static piezoresistance of the nanocomposites was characterized using a custom-built force-resistance measurement setup under compressive loading conditions.

Preparation of silver nano-particles immobilized onto chitin nano-crystals and their application to cellulose paper for imparting antimicrobial activity.

PubMed

Li, Zhihan; Zhang, Ming; Cheng, Dong; Yang, Rendang

2016-10-20

Immobilized silver nano-particles (Ag NPs) possess excellent antimicrobial properties due to their unique surface characteristics. In this paper, immobilized silver nano-particles were synthesized in the presence of chitin nano-crystals (CNC) based on the Tollens mechanism (reduction of silver ion by aldehydes in the chitosan oligosaccharides (COS)) under microwave-assisted conditions. The prepared Ag NPs-loaded CNC nano-composites were then applied onto the paper surface via coating for the preparation of antibacterial paper. Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) results confirmed that the Ag NPs were immobilized onto the CNC. The transmission electron microscope (TEM) and scanning electron microscopy (SEM) results further revealed that the spherical Ag NPs (5-12nm) were well dispersed on the surface of CNC. The coated paper made from the Ag NPs-loaded CNC nano-composites exhibited a high effectiveness of the antibacterial activity against E. coli or S. aureus. Copyright © 2016 Elsevier Ltd. All rights reserved.

Antimicrobial bacterial cellulose nanocomposites prepared by in situ polymerization of 2-aminoethyl methacrylate.

PubMed

Figueiredo, Ana R P; Figueiredo, Andrea G P R; Silva, Nuno H C S; Barros-Timmons, Ana; Almeida, Adelaide; Silvestre, Armando J D; Freire, Carmen S R

2015-06-05

Antimicrobial bacterial cellulose/poly(2-aminoethyl methacrylate) (BC/PAEM) nanocomposites were prepared by in situ radical polymerization of 2-aminoethyl methacrylate, using variable amounts of N,N-methylenebis(acrylamide) (MBA) as cross-linker. The obtained nanocomposites were characterized in terms of their structure, morphology, thermal stability, mechanical properties and antibacterial activity. The ensuing composite membranes were significantly more transparent than those of pure BC and showed improved thermal and mechanical properties. The antibacterial activity of the obtained nanocomposites was assessed towards a recombinant bioluminescent Escherichia coli and only the non-crosslinked nanocomposite (BC/PAEM) proved to have antibacterial activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Preparation and evaluation of polyurethane/cellulose nanowhisker bimodal foam nanocomposites for osteogenic differentiation of hMSCs.

PubMed

Shahrousvand, Ehsan; Shahrousvand, Mohsen; Ghollasi, Marzieh; Seyedjafari, Ehsan; Jouibari, Iman Sahebi; Babaei, Amir; Salimi, Ali

2017-09-01

Biocompatible and biodegradable polyurethanes (PUs) based on polycaprolactone diol (PCL) were prepared and filled with cellulose nanowhiskers (CNWs) obtained from wastepaper. The incorporated polyurethane nanocomposites were used to prepare foamed scaffolds with bimodal cell sizes through solvent casting/particulate leaching method. Sodium chloride and sugar porogens were also prepared to fabricate the scaffolds. The mechanical and thermal properties of PU/CNW nanocomposites were investigated. Incorporation of different CNWs resulted in various structures with tunable mechanical properties and biodegradability. All bimodal foam nanocomposites were biodegradable and also non-cytotoxic as revealed by MTT assay using SNL fibroblast cell line. PU/CNW foam scaffolds were used for osteogenic differentiation of human mesenchymal stem cells (hMSCs). Based on the results, such PU/CNW nanocomposites could support proliferation and osteogenic differentiation of hMSCs in three-dimensional synthetic extracellular matrix (ECM). Copyright © 2017 Elsevier Ltd. All rights reserved.

Preparation, characterization, and antibacterial activity of silver nanoparticle-decorated graphene oxide nanocomposite.

PubMed

Shao, Wei; Liu, Xiufeng; Min, Huihua; Dong, Guanghui; Feng, Qingyuan; Zuo, Songlin

2015-04-01

In this work, we report a facile and green approach to prepare a uniform silver nanoparticles (AgNPs) decorated graphene oxide (GO) nanocomposite (GO-Ag). The nanocomposite was fully characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, ultraviolet-visible (UV-vis) absorption spectra, and X-ray photoelectron spectroscopy (XPS), which demonstrated that AgNPs with a diameter of approximately 22 nm were uniformly and compactly deposited on GO. To investigate the silver ion release behaviors, HEPES buffers with different pH (5.5, 7, and 8.5) were selected and the mechanism of release actions was discussed in detail. The cytotoxicity of GO-Ag nanocomposite was also studied using HEK 293 cells. GO-Ag nanocomposite displayed good cytocompatibility. Furthermore, the antibacterial properties of GO-Ag nanocomposite were studied using Gram-negative E. coli ATCC 25922 and Gram-positive S. aureus ATCC 6538 by both the plate count method and disk diffusion method. The nanocomposite showed excellent antibacterial activity. These results demonstrated that GO-Ag nanocomposite, as a kind of antibacterial material, had a great promise for application in a wide range of biomedical applications.

Preparation of a porous Sn@C nanocomposite as a high-performance anode material for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zhang, Yanjun; Jiang, Li; Wang, Chunru

2015-07-01

A porous Sn@C nanocomposite was prepared via a facile hydrothermal method combined with a simple post-calcination process, using stannous octoate as the Sn source and glucose as the C source. The as-prepared Sn@C nanocomposite exhibited excellent electrochemical behavior with a high reversible capacity, long cycle life and good rate capability when used as an anode material for lithium ion batteries.A porous Sn@C nanocomposite was prepared via a facile hydrothermal method combined with a simple post-calcination process, using stannous octoate as the Sn source and glucose as the C source. The as-prepared Sn@C nanocomposite exhibited excellent electrochemical behavior with a high reversible capacity, long cycle life and good rate capability when used as an anode material for lithium ion batteries. Electronic supplementary information (ESI) available: Detailed experimental procedure and additional characterization, including a Raman spectrum, TGA curve, N2 adsorption-desorption isotherm, TEM images and SEM images. See DOI: 10.1039/c5nr03093e

Many Body Effects on Particle Diffusion in Polymer Nanocomposites

NASA Astrophysics Data System (ADS)

Dell, Zachary E.; Schweizer, Kenneth S.

2014-03-01

Recent statistical mechanical theories of nanoparticle motion in polymer melts and networks have focused on the dilute particle limit. By combining PRISM theory predictions for microscopic structural correlations, and a new formulation of self-consistent dynamical mode coupling theory, we extend dilute theories to finite filler loading. As a minimalist model, the polymer dynamics are first assumed to be unperturbed by the presence of the nanoparticles. The long time particle diffusivity in unentangled and entangled melts is determined as a function of polymer tube diameter and radius of gyration, nanoparticle diameter, and polymer-filler attraction strength under both constant volume and constant pressure situations. The influence of nanocomposite statistical structure (depletion, steric stabilization, bridging) on dynamics is also investigated. Using recent theoretical developments for predicting tube diameters in nanocomposites, the consequences of filler-induced tube dilation on nanoparticle motion is established. In entangled melts, increasing filler loading first modestly speeds up diffusion, and then dramatically when the inter-filler separation becomes smaller than the tube diameter. At very high loadings, a filler glass transition is generically predicted.

Enhanced Cyanate Ester Nanocomposites through Improved Nanoparticle Surface Interactions

DTIC Science & Technology

2013-05-01

and a chemically active 3- aminopropyl surface. The cure behavior and thermal properties of the cyanate ester/modified silica nanocomposites were...area of 150 m 2 /g. Nanoparticles with a chemically active 3- aminopropyl surface were prepared by treating Aerosil 200 particles with 3...however, was visibly observed to severely undercure the nanocomposites with octyl and 3- aminopropyl surface moieties, providing a good initial

Preparation and Characterization of Novel Montmorillonite Nanocomposites

NASA Astrophysics Data System (ADS)

Mansa, Rola

Clay minerals have historically played a consequential role in human health. While the beginnings were rooted in geophagy, a primitive act of consuming earth, the health-related uses of clay minerals have evolved and diversified over time.. As excipients in pharmaceutical formulations, clay minerals can attribute novel properties onto intercalated compounds. Intercalating oxybenzone, a UV filter, within the interlamellar space of montmorillonite is desirable in order to minimize direct contact with skin. Intercalating resveratrol, a compound known for attributing beneficial effects onto human health, may be advantageous since this compound is susceptible to cis-trans isomerisation. The strategy of using alkylammonium--modified clay was undertaken and proved successful for the intercalation of oxybenzone. The field of biopolymer/layered silicate nanocomposites is heavily researched for use in a multitude of applications. Novel montmorillonite nanocomposites were prepared with neutral guar gum and cationic guar gum, using an environmentally friendly process and are fully characterized.

Preparation of bulk superhard B-C-N nanocomposite compact

DOEpatents

Zhao, Yusheng [Los Alamos, NM; He, Duanwei [Sichuan, CN

2011-05-10

Bulk, superhard, B--C--N nanocomposite compacts were prepared by ball milling a mixture of graphite and hexagonal boron nitride, encapsulating the ball-milled mixture at a pressure in a range of from about 15 GPa to about 25 GPa, and sintering the pressurized encapsulated ball-milled mixture at a temperature in a range of from about 1800-2500 K. The product bulk, superhard, nanocomposite compacts were well sintered compacts with nanocrystalline grains of at least one high-pressure phase of B--C--N surrounded by amorphous diamond-like carbon grain boundaries. The bulk compacts had a measured Vicker's hardness in a range of from about 41 GPa to about 68 GPa.

IDM release behavior and surface characteristics of the novel Cu/IDM/LDPE nanocomposite for intrauterine device.

PubMed

Yang, Zhihong; Xie, Changsheng; Xiang, Hua; Feng, Jinqing; Xia, Xianping; Cai, Shuizhou

2009-03-01

Copper/indomethacin/low-density polyethylene (Cu/IDM/LDPE) nanocomposite was prepared as a novel material for intra-uterine device (IUD). IDM release profile of the nanocomposite was investigated by using spectrophotometer. The results show that IDM release rate of Cu/IDM/LDPE nanocomposite is higher in simulated uterine solution than that in methanol, confirming that the release process of IDM is dominated mainly by pore diffusion. The decrease in copper particle size and the increase in copper mass content all accelerate IDM release, indicating that IDM release rate can be adjusted by changing copper loading or copper particle size. The surface of the incubated nanocomposite was characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray microanalysis. A few deposits composed of P, Cl, Ca, Cu and O were observed on the nanocomposite surface, which may be related to the presence of IDM particles with large particle size.

The formation of hollow poly(methyl methacrylate)/multiwalled carbon nanotube nanocomposite cylinders by microwave irradiation.

PubMed

Wang, Huan; Feng, Jiyun; Hu, Xijun; Ming Ng, Ka

2009-03-04

Poly(methyl methacrylate) (PMMA)/multiwalled carbon nanotube (MWCNT) nanocomposite particles with 1, 2 and 4 wt% of MWCNTs were prepared by mechanical grinding of PMMA and MWCNT powders in a mortar at room temperature. Both scanning electron microscopy and Raman scattering characterizations revealed that these nanocomposite particles consist of a PMMA core and a MWCNT shell. The PMMA/MWCNT nanocomposite particles were used to fabricate the corresponding nanocomposites in the form of a hollow cylinder with various diameters and heights under 700 W microwave irradiation within 1 min. A mechanism for the fast microwave assisted forming process is proposed. These experimental results may lead to a new technology for forming hollow polymeric articles that is different from the conventional injection and blowing process.

Preparation of Electrically Conductive Polystyrene/Carbon Nanofiber Nanocomposite Films

ERIC Educational Resources Information Center

Sun, Luyi; O'Reilly, Jonathan Y.; Tien, Chi-Wei; Sue, Hung-Jue

2008-01-01

A simple and effective approach to prepare conductive polystyrene/carbon nanofiber (PS/CNF) nanocomposite films via a solution dispersion method is presented. Inexpensive CNF, which has a structure similar to multi-walled carbon nanotubes, is chosen as a nanofiller in this experiment to achieve conductivity in PS films. A good dispersion is…

Zn(2+) release behavior and surface characteristics of Zn/LDPE nanocomposites and ZnO/LDPE nanocomposites in simulated uterine solution.

PubMed

Yang, Zhihong; Xie, Changsheng; Xia, Xianping; Cai, Shuizhou

2008-11-01

To decrease the side effects of the existing copper-bearing intrauterine devices, the zinc/low-density polyethylene (Zn/LDPE) nanocomposite and zinc-oxide/low-density polyethylene (ZnO/LDPE) nanocomposite have been developed in our research for intrauterine devices (IUDs). In this study, the influences of preparation methods of nanocomposites and particle sizes of zinc and zinc oxide on Zn(2+) release from composites incubated in simulated uterine solution were investigated. All release profiles are biphasic: an initial rapid release phase is followed by a near zero-order release period. Zn(2+) release rates of nanocomposites prepared by compressing moulding are higher than those of the nanocomposites prepared by hot-melt extrusing. Compared with Zn(2+) release from the microcomposites, the release profiles of the nanocomposites exhibit a sharp decrease in Zn(2+) release rate in the first 18 days, an early onset of the zero-order release period and a high release rate of Zn(2+) at the later stage. The microstructure of the Zn/LDPE sample and the ZnO/LDPE sample after being incubated for 200 days was characterized by SEM, XRD and EDX techniques. The results show that the dissolution depth of ZnO/LDPE nanocomposite is about 60 mum. Lots of pores were formed on the surface of the Zn/LDPE sample and ZnO/LDPE sample, indicating that these pores can provide channels for the dissolution of nanoparticles in the matrix. The undesirable deposits that are composed of ZnO are only detected on the surface of Zn/LDPE nanocomposite, which may increase the risk of side effects associated with IUDs. It can be expected that ZnO/LDPE nanocomposite is more suitable for IUDs than Zn/LDPE nanocomposite.

Infrared light-assisted preparation of Ag nanoparticles-reduced graphene oxide nanocomposites for non-enzymatic H{sub 2}O{sub 2} sensing

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

Ji, Ye; State Key Laboratory of Transducer Technology, Chinese Academy of Sciences; Zhang, Yong

2015-12-15

Graphical abstract: An infrared light irradiation method has been developed for preparation of AgNPs/rGO nanocomposites for electrochemical detection of H{sub 2}O{sub 2}. - Highlights: • AgNPs/rGO nanocomposites have been prepared by photochemical method. • AgNPs/rGO nanocomposites exhibit good sensing performances for detection of H{sub 2}O{sub 2}. • The present work provides a simple and green method for preparation of rGO-based materials. - Abstract: A green method has been developed for preparation of Ag nanoparticles/reduced graphene oxide (AgNPs/rGO) nanocomposites by infrared light irradiation. The characterizations indicate the successful preparation of AgNPs/rGO nanocomposites. Most importantly, AgNPs/rGO nanocomposites exhibit excellent electrocatalytic activity formore » reduction of H{sub 2}O{sub 2}, leading to a high-performance non-enzymatic H{sub 2}O{sub 2} sensor with linear detection range and detection limit about 0.1 mM to 140 mM (r = 0.9896) and 3.0 μM, respectively.« less

Preparing and Testing a Magnetic Antimicrobial Silver Nanocomposite for Water Disinfection To Gain Experience at the Nanochemistry–Microbiology Interface

DOE PAGES

Furlan, Ping Y.; Fisher, Adam J.; Melcer, Michael E.; ...

2017-03-29

In this article, we describe a 2 h introductory laboratory procedure that prepares a novel magnetic antimicrobial activated carbon nanocomposite in which nanoscale sized magnetite and silver particles are incorporated (MACAg). The MACAg nanocomposite has achieved the synergistic properties derived from its components and demonstrated its applicability as an effective and recoverable antimicrobial agent for water disinfection. The principle is successfully illustrated by a significant reduction in the number of microbes in an Escherichia coli (E. coli) solution of 2 × 10 6 colony forming units following its treatment with MACAg for 10 min. The exercise allows the college studentsmore » to (1) be introduced to an exciting class of advanced materials, known as nanocomposites, at an early stage, (2) gain working experiences at nanochemistry–microbiology interface, and (3) see the use and experience the fun of chemistry. The experiment uses readily available materials, can be run in a general or introductory chemistry laboratory environment, and is well received and enjoyed by the students. Lastly, the experiment is also suitable for advanced high school students.« less

Preparing and Testing a Magnetic Antimicrobial Silver Nanocomposite for Water Disinfection To Gain Experience at the Nanochemistry–Microbiology Interface

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

Furlan, Ping Y.; Fisher, Adam J.; Melcer, Michael E.

In this article, we describe a 2 h introductory laboratory procedure that prepares a novel magnetic antimicrobial activated carbon nanocomposite in which nanoscale sized magnetite and silver particles are incorporated (MACAg). The MACAg nanocomposite has achieved the synergistic properties derived from its components and demonstrated its applicability as an effective and recoverable antimicrobial agent for water disinfection. The principle is successfully illustrated by a significant reduction in the number of microbes in an Escherichia coli (E. coli) solution of 2 × 10 6 colony forming units following its treatment with MACAg for 10 min. The exercise allows the college studentsmore » to (1) be introduced to an exciting class of advanced materials, known as nanocomposites, at an early stage, (2) gain working experiences at nanochemistry–microbiology interface, and (3) see the use and experience the fun of chemistry. The experiment uses readily available materials, can be run in a general or introductory chemistry laboratory environment, and is well received and enjoyed by the students. Lastly, the experiment is also suitable for advanced high school students.« less

Epoxy and Silicone Optical Nanocomposites Filled with Grafted Nanoparticles

NASA Astrophysics Data System (ADS)

Tao, Peng

, the grafted PGMA brushes effectively screen the van der Waals attraction between the particles, and homogenous nanoparticle dispersions of grafted nanoparticles were obtained. Transparent high refractive index TiO2/epoxy thin film and bulk nancomposites were obtained by dispersing PGMA brushes-grafted TiO2 nanoparticles into a commercial epoxy matrix. The refractive index of the nanocomposites showed a linear dependence on the volume fraction of TiO2 nanoparticles and the optical transparency could be generally described by the Rayleigh scattering model. This powerful dispersing technique was further employed to make visibly transparent, UV/IR blocking ITO/epoxy nanocomposites which can be easily applied onto glass and plastic substrates as energy saving optical coating materials. To produce transparent silicone nanocomposites, we directly coupled phosphate-terminated PDMS chains onto the optical nanoparticle surface. It was observed that the mono-modal PDMS-grafted particles usually formed agglomerates within silicone matrices, whereas the bimodal PDMS-grafted particles were able to be individually dispersed even within high molecular weight matrices. Transparent high refractive index bulk TiO2/silicone nanocomposites were successfully prepared by filling with bimodal PDMS-grafted TiO2 nanoparticles. Furthermore, we used the PDMS-grafted TiO2/silicone nanocomposite as a model system to create a methodology to predict and control the dispersion behavior of grafted nanoparticles. The good agreement between experimental observation of dispersion of mono-modal and bimodal grafted particles and theoretical prediction would better guide future experiments and lead to predictability in polymer composite design. Finally, the bimodal grafted chain design was implemented in the preparation of transparent and luminescent CdSe/silicone nanocomposites with potential application as non-scattering light conversion materials for LEDs. The homogeneous dispersion of bimodal PDMS

Effect of Processing Variables on Tensile Modulus and Morphology of Polyethylene/Clay Nanocomposites Prepared in an Internal Mixer

NASA Astrophysics Data System (ADS)

Ujianto, O.; Jollands, M.; Kao, N.

2018-03-01

A comparative study on effect of internal mixer on high density Polyethylene (HDPE)/clay nanocomposites preparation was done. Effect of temperature, rotor rotation (rpm), and mixing time, as well as rotor type (Roller and Banbury) on mechanical properties and morphology of HDPE/clay nanocomposites were studied using Box-Behnken experimental design. The model was developed according to secant modulus and confirmed to morphology analysis using Transmission Electron Microscopy (TEM). The finding suggests that there is different mechanisms occurred in each rotor to improve the mechanical properties. The mechanism in Roller is medium shear and medium diffusion, while Banbury is high shear and low diffusion. The difference in mechanism to disperse the clay particles attribute to the different optimum processing conditions in each rotor. The settings for roller samples are predicted around mid temperature, mid speed, and mid mixing time. There is no optimum setting for Banbury within the processing boundaries. The best settings for Banbury are at low, high, low settings. The morphology results showed a hybrid composite structure, with some exfoliations and some intercalations. There was a correlation between better mechanical properties and morphology with more exfoliation and thinner intercalated particles.

Effect of lignin content on a GH11 endoxylanase acting on glucuronoarabinoxylan-lignin nanocomposites.

PubMed

Boukari, Imen; Rémond, Caroline; O'Donohue, Michael; Chabbert, Brigitte

2012-06-20

The effects of lignin content on the activity and action pattern of GH11 endoxylanase from Thermobacillus xylanilyticus were investigated using in vitro reconstituted non-covalent glucuronoarabinoxylan-model lignin (GAX-DHP) nanocomposites. Four types of nanocomposites were prepared, each displaying different lignin contents. Variations in the DHP (model lignin) polymerization process were induced by increasing the coniferyl alcohol concentration. Examination of the morphology of the nanocomposites revealed globular particles enrobed in a matrix. The size of these particles increased in line with the lignin concentration. Physicochemical characterization of the in vitro reconstituted GAX-DHPs strongly suggested that increased particle size is directly related to the solubility and reactivity of coniferyl alcohol, as reflected by changes in the amount of β-O-4 linkages. Evaluation of the impact of the GH11 endoxylanase on the GAX-DHP nanocomposites revealed a negative correlation between the proportion and organization patterns of DHP in the nanocomposites and enzyme activity. Copyright © 2012 Elsevier Ltd. All rights reserved.

TiO2 nanocomposites: Preparation, characterization, mechanical and biological properties

NASA Astrophysics Data System (ADS)

Koşarsoy, Gözde; Şen, Elif Hilal; Aksöz, Nilüfer; İde, Semra; Aksoy, Hüsnü

2014-11-01

Some novel nanocomposites, which contain different concentrations of TiO2 nanopowders, were firstly prepared by using marble dust with convenient chemical components. Their nano structures characterized and distributions of the nano-aggregations related with internal structural content of the samples have been determined by X-ray Scattering Methods (SAXS and WAXS) and mechanical properties were determined by using strain-stress measurements to increase their potential usage possibility as building materials in health and research centers. In the last and important part of the study, Candida albicans and Aspergillus niger which are a significant risk to medical patients were used to investigate originally prepared nanostructured samples' photocatalyst effect. During the last part of the study, effect of UV and visible light on photocatalyst nanocomposites were also researched. Heterogeneous photocatalysts can carry out advanced oxidation processes used for an antimicrobial effect on microorganisms. TiO2 nanoparticles as one of heterogeneous photocatalysts have been shown to exhibit strong cytotoxicity when exposed to UV and visible light.

Structural and magnetic characteristics of PVA/CoFe{sub 2}O{sub 4} nano-composites prepared via mechanical alloying method

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

Rashidi, S.; Ataie, A., E-mail: aataie@ut.ac.ir

Highlights: • Single phase CoFe{sub 2}O{sub 4} nano-particles synthesized in one step by mechanical alloying. • PVA/CoFe{sub 2}O{sub 4} magnetic nano-composites were fabricated via mechanical milling. • FTIR confirmed the interaction between PVA and magnetic CoFe{sub 2}O{sub 4} particles. • Increasing in milling time and PVA amount led to well dispersion of CoFe{sub 2}O{sub 4}. - Abstract: In this research, polyvinyl alcohol/cobalt ferrite nano-composites were successfully synthesized employing a two-step procedure: the spherical single-phase cobalt ferrite of 20 ± 4 nm mean particle size was synthesized via mechanical alloying method and then embedded into polymer matrix by intensive milling. Themore » results revealed that increase in polyvinyl alcohol content and milling time causes cobalt ferrite particles disperse more homogeneously in polymer matrix, while the mean particle size and shape of cobalt ferrite have not been significantly affected. Transmission electron microscope images indicated that polyvinyl alcohol chains have surrounded the cobalt ferrite nano-particles; also, the interaction between polymer and cobalt ferrite particles in nano-composite samples was confirmed. Magnetic properties evaluation showed that saturation magnetization, coercivity and anisotropy constant values decreased in nano-composite samples compared to pure cobalt ferrite. However, the coercivity values of related nano-composite samples enhanced by increasing PVA amount due to domain wall mechanism.« less

In situ generation of sodium alginate/hydroxyapatite nanocomposite beads as drug-controlled release matrices.

PubMed

Zhang, J; Wang, Q; Wang, A

2010-02-01

In order to find a new way to slow down the release of drugs and to solve the burst release problem of drugs from traditionally used hydrogel matrices, a series of novel pH-sensitive sodium alginate/hydroxyapatite (SA/HA) nanocomposite beads was prepared by the in situ generation of HA micro-particles in the beads during the sol-gel transition process of SA. The SA/HA nanocomposites were characterized by Fourier transform IR spectroscopy, X-ray fluorescence spectrometry, scanning electron microscopy and field emission SEM in order to reveal their composition and surface morphology as well as the role that the in situ generated HA micro-particles play. The factors influencing the swelling behavior, drug loading and controlled release behavior of the SA/HA nanocomposite beads were also investigated using diclofenac sodium (DS) as the model drug. The HA micro-particles act as inorganic crosslinkers in the nanocomposites, which could contract and restrict the movability of the SA polymer chains, and then change the surface morphology and decrease the swell ratio. Meanwhile, the entrapment efficiency of DS was improved, and the burst release of DS was overcome. The factors (including concentration of Ca(2+), reaction time and temperature) affecting the growth of HA micro-particles have a clear influence on the entrapment efficiency and release rate of DS. In this work, the nanocomposite beads prepared under optimum condition could prolong the release of DS for 8h more compared with the pristine SA hydrogel beads.

An efficient method to prepare magnetic hydroxyapatite-functionalized multi-walled carbon nanotubes nanocomposite for bone defects.

PubMed

Afroze, J D; Abden, M J; Islam, M A

2018-05-01

Hydroxyapatite-functionalized multi-walled carbon nanotube (HA-fMWCNT) magnetic nanocomposite was successfully prepared using a novel slurry-compounding method. The prepared HA-fMWCNT nanocomposite with the addition of small amount (0.5 wt%) of fMWCNT exhibited much greater improvement in mechanical properties due to strong interfacial adhesion between acid-treated MWCNTs fillers and HA matrix, thus efficient stress transfer to nanotubes from the matrix. The nanocomposite exhibited excellent haemocompatibility. Fractographic analysis was performed in order to understand the fracture behavior and toughening mechanisms. The fracture mechanisms and micro-deformation were examined by studying the microstructure of arrested crack tips using field emission scanning electron microscopy (FESEM). The origination and formation of micro-cracks are the dominant fracture mechanisms and micro-deformation in the HA-fMWCNTs nanocomposite. The developed new method enables to the fabrication of magnetic HA-fMWCNTs nanocomposite with superior mechanical performance may be potential for application as high load-bearing bone implants in the biomedical field. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis and characterization of PVK/AgNPs nanocomposites prepared by laser ablation.

PubMed

Abd El-Kader, F H; Hakeem, N A; Elashmawi, I S; Menazea, A A

2015-03-05

Nanocomposites of Poly (n-vinylcarbazole) PVK/Ag nanoparticles were prepared by laser ablation of a silver plate in aqueous solution of chlorobenzene. The influences of laser parameters such as; time of irradiation, source power and wavelength (photon energy) on structural, morphological and optical properties have been investigated using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Ultraviolet-visible (UV-Vis) and Photoluminescence (PL). A correlation between the investigated properties has been discussed. XRD, TEM and PL indicated that the complexation between AgNPs and PVK in the composite system is possible. Only the reflection peak at 2θ=38° of AgNPs appeared in the composite nanoparticles while the other reflection peaks were destroyed. The nanoparticles shape and size distribution were evaluated from TEM images. TEM analysis revealed a lower average particle size at long laser irradiation time 40min and short laser wavelength 532nm together with high laser power 570mW. From UV-Visible spectra the values of absorption coefficient, absorption edge and energy tail were calculated. The reduction of band tail value with increasing the laser ablation parameters confirms the decrease of the disorder in such composite system. The PL and UV-Vis. spectra confirm that nanocomposite samples showed quantum confinement effect. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation and characterization of potato starch nanocrystal reinforced natural rubber nanocomposites.

PubMed

Rajisha, K R; Maria, H J; Pothan, L A; Ahmad, Zakiah; Thomas, S

2014-06-01

Potato starch nanocrystals were found to serve as an effective reinforcing agent for natural rubber (NR). Starch nanocrystals were obtained by the sulfuric acid hydrolysis of potato starch granules. After mixing the latex and the starch nanocrystals, the resulting aqueous suspension was cast into film by solvent evaporation method. The composite samples were successfully prepared by varying filler loadings, using a colloidal suspension of starch nanocrystals and NR latex. The morphology of the nanocomposite prepared was analyzed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). FESEM analysis revealed the size and shape of the crystal and their homogeneous dispersion in the composites. The crystallinity of the nanocomposites was studied using XRD analysis which indicated an overall increase in crystallinity with filler content. The mechanical properties of the nanocomposites such as stress-strain behavior, tensile strength, tensile modulus and elongation at break were measured according to ASTM standards. The tensile strength and modulus of the composites were found to improve tremendously with increasing nanocrystal content. This dramatic increase observed can be attributed to the formation of starch nanocrystal network. This network immobilizes the polymer chains leading to an increase in the modulus and other mechanical properties. Copyright © 2014 Elsevier B.V. All rights reserved.

Interpreting Neutron Reflectivity Profiles of Diblock Copolymer Nanocomposite Thin Films Using Hybrid Particle-Field Simulations

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

Mahalik, Jyoti P.; Dugger, Jason W.; Sides, Scott W.

Mixtures of block copolymers and nanoparticles (block copolymer nanocomposites) are known to microphase separate into a plethora of microstructures, depending on the composition, length scale and nature of interactions among its different constituents. Theoretical and experimental works on this class of nanocomposites have already high-lighted intricate relations among chemical details of the polymers, nanoparticles, and various microstructures. Confining these nanocomposites in thin films yields an even larger array of structures, which are not normally observed in the bulk. In contrast to the bulk, exploring various microstructures in thin films by the experimental route remains a challenging task. Here in thismore » work, we construct a model for the thin films of lamellar forming diblock copolymers containing spherical nanoparticles based on a hybrid particle-field approach. The model is benchmarked by comparison with the depth profiles obtained from the neutron reflectivity experiments for symmetric poly(deuterated styrene-b-n butyl methacrylate) copolymers blended with spherical magnetite nanoparticles covered with hydrogenated poly(styrene) corona. We show that the model based on a hybrid particle-field approach provides details of the underlying microphase separation in the presence of the nanoparticles through a direct comparison to the neutron reflectivity data. This work benchmarks the application of the hybrid particle-field model to extract the interaction parameters for exploring different microstructures in thin films containing block copolymers and nanocomposites.« less

Interpreting Neutron Reflectivity Profiles of Diblock Copolymer Nanocomposite Thin Films Using Hybrid Particle-Field Simulations

DOE PAGES

Mahalik, Jyoti P.; Dugger, Jason W.; Sides, Scott W.; ...

2018-04-10

Mixtures of block copolymers and nanoparticles (block copolymer nanocomposites) are known to microphase separate into a plethora of microstructures, depending on the composition, length scale and nature of interactions among its different constituents. Theoretical and experimental works on this class of nanocomposites have already high-lighted intricate relations among chemical details of the polymers, nanoparticles, and various microstructures. Confining these nanocomposites in thin films yields an even larger array of structures, which are not normally observed in the bulk. In contrast to the bulk, exploring various microstructures in thin films by the experimental route remains a challenging task. Here in thismore » work, we construct a model for the thin films of lamellar forming diblock copolymers containing spherical nanoparticles based on a hybrid particle-field approach. The model is benchmarked by comparison with the depth profiles obtained from the neutron reflectivity experiments for symmetric poly(deuterated styrene-b-n butyl methacrylate) copolymers blended with spherical magnetite nanoparticles covered with hydrogenated poly(styrene) corona. We show that the model based on a hybrid particle-field approach provides details of the underlying microphase separation in the presence of the nanoparticles through a direct comparison to the neutron reflectivity data. This work benchmarks the application of the hybrid particle-field model to extract the interaction parameters for exploring different microstructures in thin films containing block copolymers and nanocomposites.« less

Silicon-containing polymer-derived ceramic nanocomposites (PDC-NCs): preparative approaches and properties.

PubMed

Ionescu, Emanuel; Kleebe, Hans-Joachim; Riedel, Ralf

2012-08-07

Composites consist by definition of at least two materials (Gibbsian phases) with rather different properties. They exhibit a heterogeneous microstructure and possess improved properties with respect to their components. Furthermore, the design of their microstructure allows for tailoring their overall properties. In the last decades, intense work was performed on the synthesis of nanocomposites, which have the feature that at least one of their components is nanoscaled. However, the microstructure-property relationship of nanocomposite materials is still a challenging topic. This tutorial review paper deals with a special class of nanocomposites, i.e. polymer-derived ceramic nanocomposites (PDC-NCs), which have been shown to be promising materials for various structural and functional applications. Within this context, different preparative approaches for PDC-NCs as well as some of their properties will be presented and discussed. Furthermore, recent results concerning the relationship between the nano/microstructure of PDC-NCs and their properties will be highlighted.

Highly Conductive Multifunctional Graphene Polycarbonate Nanocomposites

NASA Technical Reports Server (NTRS)

Yoonessi, Mitra; Gaier, James R.

2010-01-01

Graphene nanosheet bisphenol A polycarbonate nanocomposites (0.027 2.2 vol %) prepared by both emulsion mixing and solution blending methods, followed by compression molding at 287 C, exhibited dc electrical percolation threshold of approx.0.14 and approx.0.38 vol %, respectively. The conductivities of 2.2 vol % graphene nanocomposites were 0.512 and 0.226 S/cm for emulsion and solution mixing. The 1.1 and 2.2 vol % graphene nanocomposites exhibited frequency-independent behavior. Inherent conductivity, extremely high aspect ratio, and nanostructure directed assembly of the graphene using PC nanospheres are the main factors for excellent electrical properties of the nanocomposites. Dynamic tensile moduli of nanocomposites increased with increasing graphene in the nanocomposite. The glass transition temperatures were decreased with increasing graphene for the emulsion series. High-resolution electron microscopy (HR-TEM) and small-angle neutron scattering (SANS) showed isolated graphene with no connectivity path for insulating nanocomposites and connected nanoparticles for the conductive nanocomposites. A stacked disk model was used to obtain the average particle radius, average number of graphene layers per stack, and stack spacing by simulation of the experimental SANS data. Morphology studies indicated the presence of well-dispersed graphene and small graphene stacking with infusion of polycarbonate within the stacks.

Synthesis, characterization and adsorption properties of magnetite/reduced graphene oxide nanocomposites.

PubMed

Qi, Tingting; Huang, Chenchen; Yan, Shan; Li, Xiu-Juan; Pan, Si-Yi

2015-11-01

Three kinds of magnetite/reduced graphene oxide (MRGO) nanocomposites were prepared by solvothermal, hydrothermal and co-precipitation methods. The as-prepared nanocomposites were characterized and compared by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and zeta potential. The results showed that MRGO made by different methods differed in surface functional groups, crystal structure, particle sizes, surface morphology and surface charge. Due to their unlike features, these nanocomposites displayed dissimilar performances when they were used to adsorb drugs, dyes and metal ions. The MRGO prepared by the co-precipitation method showed special adsorption ability to negative ions, but those synthesized by the solvothermal method obtained the best extraction ability and reusability to the others and showed a good prospective in magnetic solid-phase extraction. Therefore, it is highly recommended to use the right preparation method before application in order to attain the best extraction performance. Copyright © 2015 Elsevier B.V. All rights reserved.

Preparation and Electrochemical Characterization of Mesoporous Polyaniline-Silica Nanocomposites as an Electrode Material for Pseudocapacitors

PubMed Central

Zu, Lei; Cui, Xiuguo; Jiang, Yanhua; Hu, Zhongkai; Lian, Huiqin; Liu, Yang; Jin, Yushun; Li, Yan; Wang, Xiaodong

2015-01-01

Mesoporous polyaniline-silica nanocomposites with a full interpenetrating structure for pseudocapacitors were synthesized via the vapor phase approach. The morphology and structure of the nanocomposites were deeply investigated by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis and nitrogen adsorption-desorption tests. The results present that the mesoporous nanocomposites possess a uniform particle morphology and full interpenetrating structure, leading to a continuous conductive polyaniline network with a large specific surface area. The electrochemical performances of the nanocomposites were tested in a mixed solution of sulfuric acid and potassium iodide. With the merits of a large specific surface area and suitable pore size distribution, the nanocomposite showed a large specific capacitance (1702.68 farad (F)/g) due to its higher utilization of the active material. This amazing value is almost three-times larger than that of bulk polyaniline when the same mass of active material was used. PMID:28788006

Properties of nanocomposite PP fibres

NASA Astrophysics Data System (ADS)

Smole, Majda S.; Stakne, Kristina; Svetec, Diana G.; Kleinschek, Karin S.; Ribitsch, Volker

2005-06-01

PP-based nanocomposite fibres were prepared by direct polymer melt intercalation. With the intention to determine the size and dispersion of nanoparticles in the polymer matrix, fibres were plasma etched and SEM observations were performed. The influence of nanofiller content and coupling agent on electrokinetic properties was studied. PP monofilament fibres exhibit hydrophobe character with negative zeta potential value. The zeta potential value of co-polymer PP fibre decreases with increasing PPAA content and the isoelectric point IEP of co-polymer samples shifts towards acid region. Addition of modified montmorillonite due to the particles electropositive character, affects the reduction of zeta potential value and a slight shift of IEP towards neutral region is observed. Nano-particles content influences electrokinetic fibres properties, i.e. ZP value is changed, however IE point is not significantly changed by different concentrations of nanofiller. In addition to, mechanical properties of nanocomposite fibres were determined.

Preparation of Zeolite/Zinc Oxide Nanocomposites for toxic metals removal from water

NASA Astrophysics Data System (ADS)

Alswata, Abdullah A.; Ahmad, Mansor Bin; Al-Hada, Naif Mohammed; Kamari, Halimah Mohamed; Hussein, Mohd Zobir Bin; Ibrahim, Nor Azowa

This research work has proposed preparation of Zeolite/Zinc Oxide Nanocomposite (Zeolite/ZnO NCs) by using a co-precipitation method. Then, the prepared Nanocomposite has been tested for adsorption of Lead Pb (II) and Arsenic As (V) from aqueous solution under the room pressure and temperature. After that, the prepared adsorbent has been studied by several techniques. For adsorption process; the effect of the adsorbent masses, contact time, PH and initial metals concentration as well as, the kinetics and isotherm for adsorption process have been investigated. The results revealed that; ZnO nanoparticles (NPs) with average diameter 4.5 nm have successfully been loaded into Zeolite. The optimum parameters for the removal of the toxic metals 93% and 89% of Pb (II) and As (V), respectively, in 100 mg/L aqua solutions were pH4, 0.15 g and 30 min. According to the obtained results; pseudo second-order kinetic and Langmuir isotherm model have higher correlation coefficients and provided a better agreement with the experimental data. The prepared sorbent showed an economical and effective way to remove the heavy toxic metals due to its ambient operation conditions, low- consumption energy and facile regeneration method.

Polyolefin nanocomposites

DOEpatents

Chaiko, David J.

2007-01-02

The present invention relates to methods for the preparation of clay/polymer nanocomposites. The methods include combining an organophilic clay and a polymer to form a nanocomposite, wherein the organophilic clay and the polymer each have a peak recrystallization temperature, and wherein the organophilic clay peak recrystallization temperature sufficiently matches the polymer peak recrystallization temperature such that the nanocomposite formed has less permeability to a gas than the polymer. Such nanocomposites exhibit 2, 5, 10, or even 100 fold or greater reductions in permeability to, e.g., oxygen, carbon dioxide, or both compared to the polymer. The invention also provides a method of preparing a nanocomposite that includes combining an amorphous organophilic clay and an amorphous polymer, each having a glass transition temperature, wherein the organophilic clay glass transition temperature sufficiently matches the polymer glass transition temperature such that the nanocomposite formed has less permeability to a gas than the polymer.

Polymer-phyllosilicate nanocomposites and their preparation

DOEpatents

Chaiko, David J.

2007-01-09

Polymer-phyllosilicate nanocomposites that exhibit superior properties compared to the polymer alone, and methods-for producing these polymer-phyllosilicate nanocomposites, are provided. Polymeric surfactant compatabilizers are adsorbed onto the surface of hydrophilic or natural phyllosilicates to facilitate the dispersal and exfoliation of the phyllosilicate in a polymer matrix. Utilizing polymeric glycol based surfactants, polymeric dicarboxylic acids, polymeric diammonium surfactants, and polymeric diamine surfactants as compatabilizers facilitates natural phyllosilicate and hydrophilic organoclay dispersal in a polymer matrix to produce nanocomposites.

Preparation of nanocrystals and nanocomposites of nanocrystal-conjugated polymer, and their photophysical properties in confined geometries

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

Xu, Jun

2007-01-01

Semiconductors nanocrystals (NCs), also called quantum dots (QDs), have attracted tremendous interest over the past decade in the fields of physics, chemistry, and engineering. Due to the quantum-confined nature of QDs, the variation of particle size provides continuous and predictable changes in fluorescence emission. On the other hand, conjugated polymers (CPs) have been extensively studied for two decades due to their semiconductor-like optical and electronic properties. The electron and energy transfer between NCs and CPs occur in solar cells and light emitting diodes (LEDs), respectively. Placing CPs in direct contact with a NC (i.e., preparing NC-CP nanocomposites) carries advantage overmore » cases where NC aggregation dominates. Such NC-CP nanocomposites possess a well-defined interface that significantly promotes the charge or energy transfer between these two components. However, very few studies have centered on such direct integration. We prepared NCs and NC-CP nanocomposites based on heck coupling and investigated the energy and charge transfer between semiconductor NCs (i.e., CdSe QDs), CPs (i.e., poly(3-hexyl thiophene) (P3HT)) in the nanocomposites in confined geometries. Two novel strategies were used to confine NC and/or NC-CP nanocomposites: (a) directly immobilizing nanohybrids, QDs and nanorods in nanoscopic porous alumina membrane (PAM) , and (b) confining the QDs and CPs in sphere-on-flat geometry to induce self-assembly. While investigating the confinement effect, gradient concentric ring patterns of high regularity form spontaneously simply by allowing a droplet of solution containing either conjugated polymer or semiconductor nanocrystal in a consecutive stick-slip mothion in a confined geometry. Such constrained evaporation can be utilized as a simple, cheap, and robust strategy for self-assembling various materials with easily tailored optical and electronic properties into spatially ordered, two-dimensional patterns. These self

Preparation and characterization of a novel highly hydrophilic and antifouling polysulfone/nanoporous TiO2 nanocomposite membrane.

PubMed

Bidsorkhi, H Cheraghi; Riazi, H; Emadzadeh, D; Ghanbari, M; Matsuura, T; Lau, W J; Ismail, A F

2016-10-14

In this research, novel ultrafiltration nanocomposite membranes were prepared by incorporating self-synthesized nanoporous titanium dioxide (NTiO2) nanoparticles into polysulfone. The surface of the nanoparticle was treated with a silane-based modifier to improve its distribution in the host polymer. Atomic-force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller, transmission electron microscopy, energy-dispersive x-ray spectroscopy, porosity and contact angle tests were conducted to characterize the properties of the particles as well as the fabricated nanocomposite membranes. The effects of the nanoparticle incorporation were evaluated by conducting ultrafiltration experiments. It was reported that the membrane pure water flux was increased with increasing NTiO2 loading owing to the high porosity of the nanoparticles embedded and/or formation of enlarged pores upon addition of them. The antifouling capacity of the membranes was also tested by ultrafiltration of bovine serum albumin fouling solution. It was found that both water flux and antifouling capacity tended to reach desired level if the NTiO2 added was at optimized loading.

Magnetic Poly(N-isopropylacrylamide) Nanocomposites: Effect of Preparation Method on Antibacterial Properties

NASA Astrophysics Data System (ADS)

Nguyen, Nhung H. A.; Darwish, Mohamed S. A.; Stibor, Ivan; Kejzlar, Pavel; Ševců, Alena

2017-10-01

The most challenging task in the preparation of magnetic poly(N-isopropylacrylamide) (Fe3O4-PNIPAAm) nanocomposites for bio-applications is to maximise their reactivity and stability. Emulsion polymerisation, in situ precipitation and physical addition were used to produce Fe3O4-PNIPAAm-1, Fe3O4-PNIPAAm-2 and Fe3O4-PNIPAAm-3, respectively. Their properties were characterised using scanning electron microscopy (morphology), zeta-potential (surface charge), thermogravimetric analysis (stability), vibrating sample magnetometry (magnetisation) and dynamic light scattering. Moreover, we investigated the antibacterial effect of each nanocomposite against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Both Fe3O4-PNIPAAm-1 and Fe3O4-PNIPAAm-2 nanocomposites displayed high thermal stability, zeta potential and magnetisation values, suggesting stable colloidal systems. Overall, the presence of Fe3O4-PNIPAAm nanocomposites, even at lower concentrations, caused significant damage to both E. coli and S. aureus DNA and led to a decrease in cell viability. Fe3O4-PNIPAAm-1 displayed a stronger antimicrobial effect against both bacterial strains than Fe3O4-PNIPAAm-2 and Fe3O4-PNIPAAm-3. Staphylococcus aureus was more sensitive than E. coli to all three magnetic PNIPAAm nanocomposites.

Study of ceria-carbonate nanocomposite electrolytes for low-temperature solid oxide fuel cells.

PubMed

Fan, L; Wang, C; Di, J; Chen, M; Zheng, J; Zhu, B

2012-06-01

Composite and nanocomposite samarium doped ceria-carbonates powders were prepared by solid-state reaction, citric acid-nitrate combustion and modified nanocomposite approaches and used as electrolytes for low temperature solid oxide fuel cells. X-ray Diffraction, Scanning Electron Microscope, low-temperature Nitrogen Adsorption/desorption Experiments, Electrochemical Impedance Spectroscopy and fuel cell performance test were employed in characterization of these materials. All powders are nano-size particles with slight aggregation and carbonates are amorphous in composites. Nanocomposite electrolyte exhibits much lower impedance resistance and higher ionic conductivity than those of the other electrolytes at lower temperature. Fuel cell using the electrolyte prepared by modified nanocomposite approach exhibits the best performance in the whole operation temperature range and achieves a maximum power density of 839 mW cm(-2) at 600 degrees C with H2 as fuel. The excellent physical and electrochemical performances of nanocomposite electrolyte make it a promising candidate for low-temperature solid oxide fuel cells.

Nanocelluloses from jute fibers and their nanocomposites with natural rubber: Preparation and characterization.

PubMed

Thomas, Martin George; Abraham, Eldho; Jyotishkumar, P; Maria, Hanna J; Pothen, Laly A; Thomas, Sabu

2015-11-01

Nanocellulose fibers having an average diameter of 50nm were isolated from raw jute fibers by steam explosion process. The isolation of nanocellulose from jute fibers by this extraction process is proved by SEM, XRD, FTIR, birefringence and TEM characterizations. This nanocellulose was used as the reinforcing agent in natural rubber (NR) latex along with crosslinking agents to prepare crosslinked nanocomposite films. The effects of nanocellulose loading on the morphology and mechanics of the nanocomposites have been carefully analyzed. Significant improvements in the Young's modulus and tensile strength of the nanocomposite were observed because of the reinforcing ability of the nanocellulose in the rubber matrix. A mechanism is suggested for the formation of the Zn-cellulose complex. The three-dimensional network of cellulose nanofibers (cellulose/cellulose network and Zn/cellulose network) in the NR matrix plays a major role in improving the properties of the crosslinked nanocomposites. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of heterocyclic based organoclays on the properties of polyimide-clay nanocomposites.

PubMed

Krishnan, P Santhana Gopala; Joshi, Mangala; Bhargava, Prachur; Valiyaveettil, Suresh; He, Chaobin

2005-07-01

Polyimide-clay nanocomposites were prepared from their precursor, namely, polyamic acid, by the solution-casting method. Organomodified montmorillonite (MMT) clay was prepared by treating Na+MMT (Kunipia F) with three different intercalating agents, namely, piperazine dihydrochloride, 1,3-bis(4-piperidinylpropane) dihydrochloride and 4,4'-bipiperidine dihydrochloride at 80 degrees C. Polyamic acid solutions containing various weight percentages of organomodified MMT were prepared by reacting 4,4'-(1,1'-biphenyl-4,4'-diyldioxy)dianiline with bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride in N-methyl-2-pyrrolidinone containing dispersed particles of organomodified MMT at 20 degrees C. Nanocomposite films were prepared from these solutions by solution casting and heated subsequently at a programmed heating rate. These films were transparent and brown in color. The extent of layer separation in nanocomposite films depends upon the chemical structure of the organoclay. These films were characterized by inherent viscosity, FT-IR, DSC, TMA, WAXD, TEM, UV, and TGA. The tensile behavior and surface energy studies were also investigated. The nanocomposite films had superior tensile properties, thermal behavior, and solvent resistance. Among the three organoclays, piperazine dihydrochloride was the best modifier.

Chemically stabilized reduced graphene oxide/zirconia nanocomposite: synthesis and characterization

NASA Astrophysics Data System (ADS)

Sagadevan, Suresh; Zaman Chowdhury, Zaira; Enamul Hoque, Md; Podder, Jiban

2017-11-01

In this research, chemical method was used to fabricate reduced graphene oxide/zirconia (rGO/ZrO2) nanocomposite. X-ray Diffraction analysis (XRD) was carried out to examine the crystalline structure of the nanocomposites. The nanocomposite prepared here has average crystallite size of 14 nm. The surface morphology was observed using scanning electron microscopic analysis (SEM) coupled with electron dispersion spectroscopy (EDS) to detect the chemical element over the surface of the nanocomposites. High-resolution Transmission electron microscopic analysis (HR-TEM) was carried out to determine the particle size and shape of the nanocomposites. The optical property of the prepared samples was determined using UV-visible absorption spectrum. The functional groups were identified using FTIR and Raman spectroscopic analysis. Efficient, cost effective and properly optimized synthesis process of rGO/ZrO2 nanocomposite can ensure the presence of infiltrating graphene network inside the ZrO2 matrix to enhance the electrical properties of the hybrid composites up to a greater scale. Thus the dielectric constant, dielectric loss and AC conductivity of the prepared sample was measured at various frequencies and temperatures. The analytical results obtained here confirmed the homogeneous dispersion of ZrO2 nanostructures over the surface of reduced graphene oxide nanosheets. Overall, the research demonstrated that the rGO/ZrO2 nano-hybrid structure fabricated here can be considered as a promising candidate for applications in nanoelectronics and optoelectronics.

Preparation of poly(vinyl alcohol)/kaolinite nanocomposites via in situ polymerization

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

Jia Xin; Department of Chemistry, Hexi University, Zhangye 734000; Li Yanfeng

2008-03-04

Poly(vinyl alcohol)/kaolinite intercalated nanocomposites (Kao-PVA) were prepared via in situ intercalation radical polymerization. Vinyl acetate (VAc) was intercalated into kaolinite by a displacement method using dimethyl sulfoxide/kaolinite (Kao-DMSO) as the intermediate. Then, PVAc/kaolinite (Kao-PVAc) was obtained via radical polymerization with benzoyl peroxide (BPO) as initiator. Last, PVAc/kaolinite was saponified via direct-hydrolysis with NaOH solution in order to obtain PVA/kaolinite nanocomposites, which was characterized by Fourier-Transformation spectroscopy (FTIR), wide X-ray diffraction (WXRD) and transmission electron microscopy (TEM). Their differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) results of the obtained PVA/kaolinite suggested that the thermal properties had an obvious improvement.

Preparation of Fe3O4/Bentonite Nanocomposite from Natural Iron Sand by Co-precipitation Method for Adsorbents Materials

NASA Astrophysics Data System (ADS)

Sebayang, Perdamean; Kurniawan, Candra; Aryanto, Didik; Arief Setiadi, Eko; Tamba, Konni; Djuhana; Sudiro, Toto

2018-03-01

An adsorption method is one of the effective ways to filter the heavy metals wastes in aqueous system. In this paper, the Fe3O4/bentonite nanocomposites were successfully prepared from natural iron sand by co-precipitation method. The chemical process was carried out by dissolving and hot stirring the milled iron sand and bentonite in acid solution and precipitating it by NH4OH. The sediment was then washed using distilled water to neutralize pH and dried at 100 °C for 5 hours to produce Fe3O4/bentonite powders. The samples were characterized by XRD, FTIR, BET, TEM, VSM and AAS. All samples were composed by Fe3O4 single phase with a spinnel structure and lattice parameter of 8.373 Å. The transmittance peak of FTIR curve proved that the Fe3O4 particles and bentonite had a molecular bonding. The addition of bentonite to Fe3O4 nanoparticles generally reduced the magnetic properties of Fe3O4/bentonite nanocomposites. The optimum condition of 30 wt% bentonite resulted 105.9 m2/g in surface area, 14 nm in an average particle size and 3.2 nm in pore size. It can be used as Cu and Pb adsorbent materials.

Inorganic-organic nanocomposites formed using porous ceramic particles

NASA Astrophysics Data System (ADS)

Luo, Jiazhong

Inorganic-organic nanocomposites are expected to be of great significance in new material technologies impacting many different fields. We develop new nanomaterials of this type that have an interpenetrating network structure via in-situ polymerization of monomer within the nanopores of inorganic gel particles (porosity 20-80 vol.%). Due to strong nanomechanical bonding, these thermosetting polymer composites are expected to exhibit improved mechanical performance. Particle porosity is a primary factor. In contrast to HCl-catalyzed gels, more porous HF-catalyzed gels (porosity 62 vol.%) produced higher composite wear-resistance. At the same loading, the wear rates decrease linearly with increasing filler porosity. Better wear resistance is associated with fine-scale plastic deformation as opposed to brittle fracture and particle pull-out. For the coupling of HF-catalyzed particles with gamma-methacryloxypropyl trimethoxysilane, FTIR and solid-state sp{13}C/sp{29}Si NMR show that the use of a catalyst (n-propylamine) and a nonpolar solvent (cyclohexane), causes the degree of coupling and self-condensation to increase. Ethanol competes with the silane for the surface and results in less silane self-condensation. Surprisingly, the silane diminishes the composite wear resistance due to its pore-filling effect and the subsequent decrease in polymer interpenetration. A transition from plastic deformation to brittle fracture is involved. A new sol-gel technique was found to prepare porous (up to 76.54 vol.%) silica nanoparticles from solution via sodium fluoride (NaF) salt catalysis. Full interpenetration is achieved without the use of silane coupling agents. The resulting composites displayed improved wear resistance, toughness, modulus, hardness and high compressive strength. Toughening and reinforcement can be explained by pore confinement. DMA and DEA were combined with TEM to investigate related structure and property issues. The filler matrix effect on composite

Poly methacrylic acid modified CDHA nanocomposites as potential pH responsive drug delivery vehicles.

PubMed

Victor, Sunita Prem; Sharma, Chandra P

2013-08-01

The objective of this study was to prepare pH sensitive polymethacrylic acid-calcium deficient hydroxyapatite (CDHA) nanocomposites. The CDHA nanoparticles were prepared by coprecipitation method. The modification of CDHA by methacrylic acid (MA) was achieved by AIBN initiated free radical polymerization with sodium bisulphite as catalyst followed by emulsion technique. These nanocomposites with a half life of 8h consisted of high aspect ratio, needle like particles and exhibited an increase in swelling behaviour with pH. The in vivo potential of the nanocomposites was evaluated in vitro by the results of cell aggregation, protein adsorption, MTT assay and haemolytic activity. The invitro loading and release studies using albumin as a model drug indicate that the nanocomposites gave better loading when compared to the CDHA nanoparticles and altered the drug release rates. The nanocomposites also exhibited good uptake on C6 glioma cells as studied by fluorescence microscopy. The results obtained suggest that these nanocomposites have great potential for oral controlled protein delivery and can be extended further for intracellular drug delivery applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Mechanism of Particle Formation in Silver/Epoxy Nanocomposites Obtained through a Visible-Light-Assisted in Situ Synthesis.

PubMed

dell'Erba, Ignacio E; Martínez, Francisco D; Hoppe, Cristina E; Eliçabe, Guillermo E; Ceolín, Marcelo; Zucchi, Ileana A; Schroeder, Walter F

2017-10-03

A detailed understanding of the processes taking place during the in situ synthesis of metal/polymer nanocomposites is crucial to manipulate the shape and size of nanoparticles (NPs) with a high level of control. In this paper, we report an in-depth time-resolved analysis of the particle formation process in silver/epoxy nanocomposites obtained through a visible-light-assisted in situ synthesis. The selected epoxy monomer was based on diglycidyl ether of bisphenol A, which undergoes relatively slow cationic ring-opening polymerization. This feature allowed us to access a full description of the formation process of silver NPs before this was arrested by the curing of the epoxy matrix. In situ time-resolved small-angle X-ray scattering investigation was carried out to follow the evolution of the number and size of the silver NPs as a function of irradiation time, whereas rheological experiments combined with near-infrared and ultraviolet-visible spectroscopies were performed to interpret how changes in the rheological properties of the matrix affect the nucleation and growth of particles. The analysis of the obtained results allowed us to propose consistent mechanisms for the formation of metal/polymer nanocomposites obtained by light-assisted one-pot synthesis. Finally, the effect of a thermal postcuring treatment of the epoxy matrix on the particle size in the nanocomposite was investigated.

Transmission electron microscopy of polyhydroxybutyrate-co-valerate (PHBV)/nanocrystalline cellulose (NCC) bio-nanocomposite prepared using cryo-ultramicrotomy

NASA Astrophysics Data System (ADS)

Ismarul, N. I.; Engku, A. H. E. U.; Siti, N. K.; Tay, K. Y.

2017-12-01

Environmental issues on disposal and end-of-life for product made from synthetic petroleum-derived polymers have gained increasing attention from materials scientist to search for new materials with similar physical and mechanical properties but environmental friendly in a way that they are renewable and biodegradable as well. This work is to study the effect of nanocrystalline cellulose in improving the thermal stability of polyhydroxybutyrate-co-valerate biopolymer for high temperature processing of packaging material. 10 % w/w PHBV-NCC bio-nanocomposite feedstock pellet prepared using RONDOL minilab compounder was used as the sample for the preparation of Transmission Electron Microscopy (TEM) sample. RMC Cryo-Ultramicrotomy equipment was used to prepare the ultra-thin slice of the bio-nanocomposite pellet under liquid nitrogen at - 60 °C. Diamond knife was used to slice off about 80-100 nm ultra-thin bio-nanocomposite films and was transferred into the lacey carbon film coated grid using cooled sugar solution. A few drops of phosphotungstic acid was used as negative stain to improve the contrast during the TEM analysis. HITACHI TEM systems was used to obtain the TEM micrograph of PHBV-NCC bio-nanocomposite using 80kV accelerating voltage. A well dispersed NCC in PHBV matrix, ranging from 5 to 25 nm in width was observed.

Nanoscale Design of Nano-Sized Particles in Shape-Memory Polymer Nanocomposites Driven by Electricity

PubMed Central

Lu, Haibao; Huang, Wei Min; Liang, Fei; Yu, Kai

2013-01-01

In the last few years, we have witnessed significant progress in developing high performance shape memory polymer (SMP) nanocomposites, in particular, for shape recovery activated by indirect heating in the presence of electricity, magnetism, light, radio frequency, microwave and radiation, etc. In this paper, we critically review recent findings in Joule heating of SMP nanocomposites incorporated with nanosized conductive electromagnetic particles by means of nanoscale control via applying an electro- and/or magnetic field. A few different nanoscale design principles to form one-/two-/three- dimensional conductive networks are discussed. PMID:28788303

Urchin-like CdS/ZrO2 nanocomposite prepared by microwave-assisted hydrothermal combined with ion-exchange and its multimode photocatalytic activity

NASA Astrophysics Data System (ADS)

Li, Li; Wang, Lili; Zhang, Wenzhi; Zhang, Xiuli; Chen, Xi; Dong, Xue

2014-12-01

A series of urchin-like CdS/ZrO2 nanocomposites with different mole ratios of Cd/Zr were prepared by a two-step method combining the microwave-assisted hydrothermal and ion exchange methods. The products were characterized by X-ray diffraction, ultraviolet-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and N2 adsorption-desorption measurements. The results of the study revealed that the CdS/ZrO2 nanocomposites had mixed phases of tetragonal ZrO2 and hexagonal CdS. Moreover, the samples prepared by the microwave-assisted hydrothermal method possessed the urchin-like structure with a surface composed of protrude-like nanoparticles in large quantities. The absorption in the visible region changed slightly with increasing mole ratio of Cd/Zr. Moreover, compared to the nanocomposites prepared by the conventional heating, the nanocomposites prepared by the microwave-assisted hydrothermal synthesis showed significantly different Brunauer-Emmett-Teller values, and the urchin-like CdS/ZrO2 structures were obtained. The photocatalytic degradation of methyl orange under ultraviolet (UV) light irradiation indicated that the photocatalytic activity of the CdS/ZrO2 nanocomposite with CdS/ZrO2 molar ratio of 30 % was higher than those of CdS, ZrO2, and other different ratios of CdS/ZrO2 nanocomposites. Moreover, under UV light, visible light, and microwave-assisted multimode photocatalytic degradation, the urchin-like CdS/ZrO2 nanocomposites significantly affected the photodegradation of various dyes. To understand the possible reaction mechanism of the photocatalysis by the CdS/ZrO2 nanocomposites, a series of controlled experiments were performed, and the stability and reusability of the CdS/ZrO2 nanocomposites were further investigated by the photocatalytic reaction.

Preparation and structural characterization of vulcanized natural rubber nanocomposites containing nickel-zinc ferrite nanopowders.

PubMed

Bellucci, F S; Salmazo, L O; Budemberg, E R; da Silva, M R; Rodríguez-Pérez, M A; Nobre, M A L; Job, A E

2012-03-01

Single-phase polycrystalline mixed nickel-zinc ferrites belonging to Ni0.5Zn0.5Fe2O4 were prepared on a nanometric scale (mean crystallite size equal to 14.7 nm) by chemical synthesis named the modified poliol method. Ferrite nanopowder was then incorporated into a natural rubber matrix producing nanocomposites. The samples were investigated by means of infrared spectroscopy, X-ray diffraction, scanning electron microscopy and magnetic measurements. The obtained results suggest that the base concentration of nickel-zinc ferrite nanoparticles inside the polymer matrix volume greatly influences the magnetic properties of nanocomposites. A small quantity of nanoparticles, less than 10 phr, in the nanocomposite is sufficient to produce a small alteration in the semi-crystallinity of nanocomposites observed by X-ray diffraction analysis and it produces a flexible magnetic composite material with a saturation magnetization, a coercivity field and an initial magnetic permeability equal to 3.08 emu/g, 99.22 Oe and 9.42 x 10(-5) respectively.

Comparison of the Nanostructure and Mechanical Performance of Highly Exfoliated Epoxy-Clay Nanocomposites Prepared by Three Different Protocols

PubMed Central

Shiravand, Fatemeh; Hutchinson, John M.; Calventus, Yolanda; Ferrando, Francesc

2014-01-01

Three different protocols for the preparation of polymer layered silicate nanocomposites based upon a tri-functional epoxy resin, triglycidyl para-amino phenol (TGAP), have been compared in respect of the cure kinetics, the nanostructure and their mechanical properties. The three preparation procedures involve 2 wt% and 5 wt% of organically modified montmorillonite (MMT), and are: isothermal cure at selected temperatures; pre-conditioning of the resin-clay mixture before isothermal cure; incorporation of an initiator of cationic homopolymerisation, a boron tri-fluoride methyl amine complex, BF3·MEA, within the clay galleries. It was found that features of the cure kinetics and of the nanostructure correlate with the measured impact strength of the cured nanocomposites, which increases as the degree of exfoliation of the MMT is improved. The best protocol for toughening the TGAP/MMT nanocomposites is by the incorporation of 1 wt% BF3·MEA into the clay galleries of nanocomposites containing 2 wt% MMT. PMID:28788672

Comparison of the Nanostructure and Mechanical Performance of Highly Exfoliated Epoxy-Clay Nanocomposites Prepared by Three Different Protocols.

PubMed

Shiravand, Fatemeh; Hutchinson, John M; Calventus, Yolanda; Ferrando, Francesc

2014-05-30

Three different protocols for the preparation of polymer layered silicate nanocomposites based upon a tri-functional epoxy resin, triglycidyl para -amino phenol (TGAP), have been compared in respect of the cure kinetics, the nanostructure and their mechanical properties. The three preparation procedures involve 2 wt% and 5 wt% of organically modified montmorillonite (MMT), and are: isothermal cure at selected temperatures; pre-conditioning of the resin-clay mixture before isothermal cure; incorporation of an initiator of cationic homopolymerisation, a boron tri-fluoride methyl amine complex, BF₃·MEA, within the clay galleries. It was found that features of the cure kinetics and of the nanostructure correlate with the measured impact strength of the cured nanocomposites, which increases as the degree of exfoliation of the MMT is improved. The best protocol for toughening the TGAP/MMT nanocomposites is by the incorporation of 1 wt% BF₃·MEA into the clay galleries of nanocomposites containing 2 wt% MMT.

Visible-light induced anti-bacterial and self-cleaning waterborne polyacrylic coating modified with TiO2/polypyrrole nanocomposite; preparation and characterization

NASA Astrophysics Data System (ADS)

Nosrati, Rahimeh; Olad, Ali; Maryami, Fatemeh

2018-07-01

Nowadays, self-cleaning technology is used in various industries to decreasing the time, energy consumption and costs of surface servicing as well as the increasing of surface durability. Self-cleaning and anti-bacterial coatings can be made by the addition of suitable additives to a polymer matrix with good properties. In the present research, TiO2/polypyrrole nanocomposites were prepared in different TiO2 to polypyrrole weight ratios and used in various percent as an additive in waterborne commercial grade polyacrylic latex. Characterization and evaluation of structural and morphological features of nanocomposites and coatings were performed by FTIR, XRD, UV-Vis and FESEM techniques. By the addition of prepared nanocomposites as an additive to the polyacrylic matrix, the hydrophilic, water resistant, anti-bacterial, and photocatalytic coatings were prepared. The TiO2 to polypyrrole weight ratio of TiO2/polypyrrole nanocomposites and the percent of nanocomposite additive in the polymeric matrix were optimized. According to the results, the coating containing 2% and 3% of TiO2/polypyrrole nanocomposite with TiO2 to polypyrrole weight ratio of 100:10 are proposed as the best coating formulations in the formulations examined in this work, due to their good properties in the most of experiments.

Improvement of mechanical and thermal properties of high energy electron beam irradiated HDPE/hydroxyapatite nano-composite

NASA Astrophysics Data System (ADS)

Mohammadi, M.; Ziaie, F.; Majdabadi, A.; Akhavan, A.; Shafaei, M.

2017-01-01

In this research work, the nano-composites of high density polyethylene/hydroxyapatite samples were manufactured via two methods: In the first method, the granules of high density polyethylene and nano-structure hydroxyapatite were processed in an internal mixer to prepare the nano-composite samples with a different weight percentage of the reinforcement phase. As for the second one, high density polyethylene was prepared in nano-powder form in boiling xylene. During this procedure, the hydroxyapatite nano-powder was added with different weight percentages to the solvent to obtain the nano-composite. In both of the procedures, the used hydroxyapatite nano-powder was synthesized via hydrolysis methods. The samples were irradiated under 10 MeV electron beam in 70-200 kGy of doses. Mechanical, thermal and morphological properties of the samples were investigated and compared. The results demonstrate that the nano-composites which we have prepared using nano-polyethylene, show better mechanical and thermal properties than the composites prepared from normal polyethylene granules, due to the better dispersion of nano-particles in the polymer matrix.

Preparation and characterization of a novel micro- and nanocomposite hydrogels containing cellulosic fibrils

USDA-ARS?s Scientific Manuscript database

In recent years, the preparation of cellulosic composites and nanocomposites has become an important approach because of the wide abundance of cellulose, its biodegradability, renewability, and the ability to effectively reinforce a polymer matrix in an environmentally benign nature. The main object...

Preparation, characterization and X-ray attenuation property of Gd2O3-based nanocomposites

NASA Astrophysics Data System (ADS)

Jayakumar, Sangeetha; Saravanan, T.; Philip, John

2017-11-01

In an attempt to develop an alternate to lead-based X-ray shielding material, we describe the X-ray attenuation property of nanocomposites containing Gd2O3 as nanofiller and silicone resin as matrix, prepared by a simple solution-casting technique. Gd2O3 nanoparticles of size 30 and 56 nm are used at concentrations of 25 and 2.5 wt%. The nanoparticles and the nanocomposites are characterized using X-ray diffraction (XRD) studies, small angle X-ray spectroscopy (SAXS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and atomic force microscopy (AFM). The X-ray attenuation property of nanocomposites, studied using an industrial X-ray unit, shows that nanocomposites containing nanoparticles of size 56 nm (G2) exhibit better attenuation than nanocomposites containing nanoparticles of size 30 nm (G1), which is attributed to the greater interfacial interaction between the G2 nanofillers and silicone matrix. In the case of nanocomposites containing G1 nanoparticles, the interfacial interaction between the nanofiller and the matrix is so weak that it results in pulling out of nanofillers, causing voids in the matrix, which act as X-ray transparent region, thereby reducing the overall X-ray attenuation property of G1 nanocomposites. This is further corroborated from the AFM images of the nanocomposites. The weight loss and heat flow curves of pure silicone matrix and the nanocomposites containing Gd2O3 nanoparticles of size 30 and 56 nm show the degradation of silicone resin, due to chain scission, between 403 and 622 °C. The same onset temperature (403 °C) of degradation of matrix with and without nanoparticles shows that the addition of nanofillers to the matrix does not deteriorate the thermal stability of the matrix. This confirms the thermal stability of nanocomposites. Therefore, our study shows that nanocomposites containing G2 nanoparticles are potential candidates for the development of X-ray opaque fabric material.

Electrochemical Impedance Spectroscopy and Corrosion Behavior of Co/CeO2 Nanocomposite Coatings in Simulating Body Fluid Solution

NASA Astrophysics Data System (ADS)

Benea, Lidia

2013-02-01

A series of Co/CeO2 (25 nm) nanocomposite coating materials by electrodeposition were successfully prepared containing different cerium oxide composition in the cobalt-plating bath. Stainless steel (304L) was used as support material for nanocomposite coatings. The nano-CeO2 is uniformly incorporated into cobalt matrix, and the effect on surface morphologies was identified by scanning electron microscopy with energy-dispersive X-ray analysis. Codeposition of nano-CeO2 particles with cobalt disturbs the regular surface morphology of the cobalt coatings. It should be noted that the as-prepared Co/CeO2 nanocomposite coatings were found to be much superior in corrosion resistance over those of pure cobalt coatings materials based on a series of electrochemical impedance spectroscopy measurements in simulating body fluid solution. With increase in the nano-CeO2 particles concentration in the cobalt electrolyte, it is observed that the corrosion resistance of Co/CeO2 increases. Co/CeO2 nanocomposite coatings have higher polarization resistance as compared with pure cobalt layers in simulating body fluid solution.

Properties of Au/Copper oxide nanocomposite prepared by green laser irradiation of the mixture of individual suspensions

NASA Astrophysics Data System (ADS)

Aazadfar, Parvaneh; Solati, Elmira; Dorranian, Davoud

2018-04-01

The fundamental wavelength of a Q-switched pulsed Nd:YAG laser was employed to produce Au and copper oxide nanoparticles via pulsed laser ablation method in water. Different volumetric ratio of nanoparticles were mixed and irradiated by the second harmonic pulses of the Nd:YAG laser to prepare Au/Copper oxide nanocomposite. The experimental investigation was dedicated to study the properties of Au/Copper oxide nanocomposite as a function of volumetric ratio of Au nanoparticles and copper oxide nanoparticles. Nanocomposites of Au and copper oxide were found almost spherical in shape. Adhesion of spherical nanostructure in Au/Copper oxide nanocomposites was decreased with increasing the concentration of Au nanoparticles. Crystalline phase of the Au/Copper oxide nanocomposites differs with the change in the volumetric ratio of Au and copper oxide nanoparticles. The intensity of surface plasmon resonance of Au nanoparticles was decreased after irradiation. Au/Copper oxide nanocomposites suspensions have emissions in the visible range. Results reveal that green laser irradiation of nanoparticle suspensions is an appropriate method to synthesize Au based nanocomposites with controlled composition and size.

Electrochromic nanocomposite films

DOEpatents

Milliron, Delia; Llordes, Anna; Buonsanti, Raffaella; Garcia, Guillermo

2018-04-10

The present invention provides an electrochromic nanocomposite film. In an exemplary embodiment, the electrochromic nanocomposite film, includes (1) a solid matrix of oxide based material and (2) transparent conducting oxide (TCO) nanostructures embedded in the matrix. In a further embodiment, the electrochromic nanocomposite film farther includes a substrate upon which the matrix is deposited. The present invention also provides a method of preparing an electrochromic nanocomposite film.

Weathering of a carbon nanotube/epoxy nanocomposite under UV light and in water bath: impact on abraded particles

NASA Astrophysics Data System (ADS)

Schlagenhauf, Lukas; Kianfar, Bahareh; Buerki-Thurnherr, Tina; Kuo, Yu-Ying; Wichser, Adrian; Nüesch, Frank; Wick, Peter; Wang, Jing

2015-11-01

Weathering processes can influence the surface properties of composites with incorporated nanoparticles. These changes may affect the release behavior of nanoparticles when an abrasion process is applied. Therefore, the influence of two different weathering processes, immersion in water and exposure to UV light, on the properties of abraded particles from a carbon nanotube (CNT)/epoxy nanocomposite was investigated. The investigation included the measurement of the weathering impact on the surface chemistry of the exposed samples, the particle size of abraded particles, the quantity of exposed CNTs in the respirable part of the abraded particles, and the toxicity of abraded particles, measured by in vitro toxicity tests using the THP-1 monocyte-derived macrophages. The results showed that weathering by immersion in water had no influence on the properties of abraded particles. The exposure to UV light caused a degradation of the epoxy on the surface, followed by delamination of an approx. 2.5 μm thick layer. An increased quantity of exposed CNTs in abraded particles was not found; on the contrary, longer UV exposure times decreased the released fraction of CNTs from 0.6% to 0.4%. The toxicity tests revealed that abraded particles from the nanocomposites did not induce additional acute cytotoxic effects compared to particles from the neat epoxy.Weathering processes can influence the surface properties of composites with incorporated nanoparticles. These changes may affect the release behavior of nanoparticles when an abrasion process is applied. Therefore, the influence of two different weathering processes, immersion in water and exposure to UV light, on the properties of abraded particles from a carbon nanotube (CNT)/epoxy nanocomposite was investigated. The investigation included the measurement of the weathering impact on the surface chemistry of the exposed samples, the particle size of abraded particles, the quantity of exposed CNTs in the respirable part of

Preparation and Investigation of Amphiphilic Block Copolymers/Fullerene Nanocomposites as Nanocarriers for Hydrophobic Drug.

PubMed

Tan, Qinggang; Chu, Yanyan; Bie, Min; Wang, Zihao; Xu, Xiaoyan

2017-02-16

Biopolymer/inorganic material nanocomposites have attracted increasing interest as nanocarriers for delivering drugs owing to the combined advantages of both biopolymer and inorganic materials. Here, amphiphilic block copolymer/fullerene nanocomposites were prepared as nanocarriers for hydrophobic drug by incorporation of C60 in the core of methoxy polyethylene glycol-poly(d,l-lactic acid) (MPEG-PDLLA) micelles. The structure and morphology of MPEG-PDLLA/C60 nanocomposites were characterized using transmission electron microscopy, dynamic light scattering, high-resolution transmission electron microscopy, and thermal gravimetric analysis. It was found that the moderate amount of spherical C60 incorporated in the MPEG-PDLLA micelles may cause an increase in the molecular chain space of PDLLA segments in the vicinity of C60 and, thus, produce a larger cargo space to increase drug entrapment and accelerate the drug release from nanocomposites. Furthermore, sufficient additions of C60 perhaps resulted in an aggregation of C60 within the micelles that decreased the drug entrapment and produced a steric hindrance for DOX released from the nanocomposites. The results obtained provide fundamental insights into the understanding of the role of C60 in adjusting the drug loading and release of amphiphilic copolymer micelles and further demonstrate the future potential of the MPEG-PDLLA/C60 nanocomposites used as nanocarriers for controlled drug-delivery applications.

Highly Efficient Near Infrared Photothermal Conversion Properties of Reduced Tungsten Oxide/Polyurethane Nanocomposites

PubMed Central

Chala, Tolesa Fita; Wu, Chang-Mou; Chou, Min-Hui; Gebeyehu, Molla Bahiru; Cheng, Kuo-Bing

2017-01-01

In this work, novel WO3-x/polyurethane (PU) nanocomposites were prepared by ball milling followed by stirring using a planetary mixer/de-aerator. The effects of phase transformation (WO3 → WO2.8 → WO2.72) and different weight fractions of tungsten oxide on the optical performance, photothermal conversion, and thermal properties of the prepared nanocomposites were examined. It was found that the nanocomposites exhibited strong photoabsorption in the entire near-infrared (NIR) region of 780–2500 nm and excellent photothermal conversion properties. This is because the particle size of WO3-x was greatly reduced by ball milling and they were well-dispersed in the polyurethane matrix. The higher concentration of oxygen vacancies in WO3-x contribute to the efficient absorption of NIR light and its conversion into thermal energy. In particular, WO2.72/PU nanocomposites showed strong NIR light absorption of ca. 92%, high photothermal conversion, and better thermal conductivity and absorptivity than other WO3/PU nanocomposites. Furthermore, when the nanocomposite with 7 wt % concentration of WO2.72 nanoparticles was irradiated with infrared light, the temperature of the nanocomposite increased rapidly and stabilized at 120 °C after 5 min. This temperature is 52 °C higher than that achieved by pure PU. These nanocomposites are suitable functional materials for solar collectors, smart coatings, and energy-saving applications. PMID:28737689

Synthesis and characterization of Nafion/TiO2 nanocomposite membrane for proton exchange membrane fuel cell.

PubMed

Kim, Tae Young; Cho, Sung Yong

2011-08-01

In this study, the syntheses and characterizations of Nafion/TiO2 membranes for a proton exchange membrane fuel cell (PEMFC) were investigated. Porous TiO2 powders were synthesized using the sol-gel method; with Nafion/TiO2 nanocomposite membranes prepared using the casting method. An X-ray diffraction analysis demonstrated that the synthesized TiO2 had an anatase structure. The specific surface areas of the TiO2 and Nafion/TiO2 nanocomposite membrane were found to be 115.97 and 33.91 m2/g using a nitrogen adsorption analyzer. The energy dispersive spectra analysis indicated that the TiO2 particles were uniformly distributed in the nanocomposite membrane. The membrane electrode assembly prepared from the Nafion/TiO2 nanocomposite membrane gave the best PEMFC performance compared to the Nafion/P-25 and Nafion membranes.

[Preparation, characterization and upconversion fluorescence of NaYF4 : Yb, Er /graphene oxide nanocomposites].

PubMed

Ji, Tian-Hao; Qie, Nan; Wang, Ji-Mei; Hua, Yong-Yong; Ji, Zhi-Jiang

2013-03-01

NaYF4 : Yb, Er/rGO and SiO2-coated NaYF4 : Yb, Er/rGO nanocomposites can be prepared through "one-pot" and directly mixing preparation routes. Various measurement results show that the NaYF4 : Yb, Er in the nanocomposites exhibits a cubic a-type structure and nanoparticle-like morphology with a diameter range of 30-70 nm; the rGO layers are well-dispersed in the nanocomposites, and whereas the rGO obtained from "one-pot" preparation renders relatively better dispersion. Raman spectra demonstrate that there exists a surface coupling action between the two kinds of nanomaterials, and with the increase in the relative rGO content, such action becomes stronger. UC fluorescence measurement results reveal that the rGO has significantly quenching effect and optical-limiting performance on the UC fluorescence, particularly on the red-emission of the NaYFa : Yb, Er or SiO2-coated NaYF4 : Yb, Er nanoparticles. The red-emission intensity gradually decreases with an increase in the rGO content, but the green-emission shows less change. It should be stressed that, in comparison with NaYF4 : Yb, Er/rGO, with a similar rGO content, the red-emission intensity of SiO2-coated NaYF4 : Yb, Er/rGO decreases much obviously due to a stronger light-absorption caused by part rGO aggregation.

Facile preparation of polypyrrole/graphene oxide nanocomposites with large areal capacitance using electrochemical codeposition for supercapacitors

NASA Astrophysics Data System (ADS)

Zhou, Haihan; Han, Gaoyi; Xiao, Yaoming; Chang, Yunzhen; Zhai, Hua-Jin

2014-10-01

A simple and low-cost electrochemical codeposition method has been introduced to fabricate polypyrrole/graphene oxide (PPy/GO) nanocomposites and the areal capacitance of conducting polymer/GO composites is reported for the first time. Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) are implemented to determine the PPy/GO nanocomposites are successfully prepared and the interaction between PPy and GO. The as-prepared PPy/GO nanocomposites show the curly sheet-like morphology, superior capacitive behaviors and cyclic stability. Furthermore, the varying deposition time is implemented to investigate the impact of the loading amount on electrochemical behavior of the composites, and a high areal capacitance of 152 mF cm-2 is achieved at 10 mV s-1 CV scan. However, the thicker films caused by the long deposition time would result in larger diffusion resistance of electrolyte ions, consequently exhibit the relatively lower capacitance value at the high current density. The GCD tests indicate moderate deposition time is more suitable for the fast charge/discharge. Considering the very simple and effective synthetic process, the PPy/GO nanocomposites with relatively high areal capacitance are competitive candidate for supercapacitor application, and its capacitive performances can be easily tuned by varying the deposition time.

Proton exchange membranes for application in fuel cells: grafted silica/SPEEK nanocomposite elaboration and characterization.

PubMed

Reinholdt, Marc X; Kaliaguine, Serge

2010-07-06

Hydrogen technologies and especially fuel cells are key components in the battle to find alternate sources of energy to the highly polluting and economically constraining fossil fuels in an aim to preserve the environment. The present paper shows the synthesis of surface functionalized silica nanoparticles, which are used to prepare grafted silica/SPEEK nanocomposite membranes. The nanoparticles are grafted either with hexadecylsilyl or aminopropyldimethylsilyl moieties or both. The synthesized particles are analyzed using XRD, NMR, TEM, and DLS to collect information on the nature of the particles and the functional groups, on the particle sizes, and on the hydrophilic/hydrophobic character. The composite membranes prepared using the synthesized particles and two SPEEK polymers with sulfonation degrees of 69.4% and 85.0% are characterized for their proton conductivity and water uptake properties. The corresponding curves are very similar for the composites prepared with both polymers and the nanoparticles bearing the two functional groups. The composites prepared with the nanoparticles bearing solely the aminopropyldimethylsilyl moiety exhibit lower conductivity and water uptake, possibly due to higher interaction of the polymer sulfonic acid sites with the amine groups. The composites prepared with the nanoparticles bearing solely the hexadecylsilyl moiety were not further investigated because of very high particles segregation. A study of the proton conductivity as a function of temperature was performed on selected membranes and showed that nanocomposites made with nanoparticles bearing both functional moieties have a higher conductivity at higher temperatures.

Preparation and characterization of polymer nanocomposites coated magnetic nanoparticles for drug delivery applications

NASA Astrophysics Data System (ADS)

Prabha, G.; Raj, V.

2016-06-01

In the present research work, the anticancer drug 'curcumin' is loaded with Chitosan (CS)-polyethylene glycol (PEG)-polyvinylpyrrolidone (PVP) (CS-PEG-PVP) polymer nanocomposites coated with superparamagnetic iron oxide (Fe3O4) nanoparticles. The system can be used for targeted and controlled drug delivery of anticancer drugs with reduced side effects and greater efficiency. The prepared nanoparticles were characterized by Fourier transmission infrared spectroscopy (FTIR), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Curcumin drug loaded Fe3O4-CS, Fe3O4-CS-PEG and Fe3O4-CS-PEG-PVP nanoparticles exhibited the mean particle size in the range of 183-390 nm with a zeta potential value of 26-41 mV as measured using Malvern Zetasizer. The encapsulation efficiency, loading capacity and in-vitro drug release behavior of curcumin drug loaded Fe3O4-CS, Fe3O4-CS-PEG and Fe3O4-CS-PEG-PVP nanoparticles were studied using UV spectrophotometer. Besides, the cytotoxicity of the prepared nanoparticles using MTT assay was also studied. The curcumin drug release was examined at different pH medium and it was proved that the drug release depends upon the pH medium in addition to the nature of matrix.

Hydrothermal synthesis of carbonyl iron-carbon nanocomposite: Characterization and electromagnetic performance

NASA Astrophysics Data System (ADS)

Pourabdollahi, Hakimeh; Zarei, Ali Reza

In this research, the electromagnetic absorption properties of the carbonyl iron-carbon (CI/C) nanocomposite prepared via hydrothermal reaction using glucose as carbon precursor was studied in the range of 8.2-12.4 GHz. In hydrothermal reaction, glucose solution containing CI particles, placed in autoclave for 4 h under 453 K. Using surface coating technology is a method that prevents Cl oxidation and improves CI electromagnetic absorption. The structure, morphology and magnetic performances of the prepared nanocomposites were characterized by X-ray diffraction (XRD), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The electromagnetic properties including complex permittivity (εr), the permeability (μr), dielectric loss, magnetic loss, reflection loss, and attenuation constant were investigated using a vector network analyzer. For The CI/C nanocomposite, the bandwidth of -10 dB and -20 dB were obtained in the frequency range of 9.8-12.4 and 11.0-11.8 GHz, respectively. As well as, the reflection loss was -46.69 dB at the matching frequency of 11.5 GHz, when the matching thickness was 1.3 mm. While for CI particles the reflection loss for 4.4 mm thickness was -16.86 dB at the matching frequency of 12.3 GHz. The results indicate that the existence layer of carbon on carbonyl iron enhance the electromagnetic absorbing properties. Therefore, this nanocomposite can be suitable for in the radar absorbing coatings.

Preparation of Ag/SiO2 nanocomposite and assessment of its antifungal effect on soybean plant (a Vietnamese species DT-26)

NASA Astrophysics Data System (ADS)

Chau Nguyen, Hoai; Thuy Nguyen, Thi; Hien Dao, Trong; Buu Ngo, Quoc; Pham, Hoang Long; Nguyen, Thi Bich Ngoc

2016-12-01

Soybean crop losses due to fungal diseases are considerable and directly depend on the severity of the disease. The objective of this study was to assess antifungal activity of silver/silica (Ag/SiO2) nanocomposite against crop pathogenic fungi (Fusarium oxysporium and Rhizoctonia solani) in soybean farming. Firstly, silica particles with a size ranging from 20 to 30 nm were modified with 3-aminopropyl triethoxysilane (APTES) for 2 h. Then these amino acid - functionalized silica particles were exposed to silver ion solution followed by reduction of silver ions with sodium borohydride to form Ag/SiO2 nanocomposite. The formation of the linkage between APTES and silica particles was confirmed by Fourier transform infrared (FTIR) spectroscopy. The surface plasmon absorption maximum at 400 nm confirmed the nano essence of the silver particles on silica particles. For the seed coating, bentonite from Lam Dong deposit, Vietnam, was used as an encapsulation substance, while carboxymethyl cellulose (CMC) was used as a binding agent. The assessment of fungicidal activity of the Ag/SiO2 nanocomposite produced showed that this product is effective in inhibition of the pathogenic fungi in soybean plant.

Novel multifunctional titania-silica-lanthanum phosphate nanocomposite coatings through an all aqueous sol-gel process.

PubMed

Smitha, Venu Sreekala; Jyothi, Chembolli Kunhatta; Peer, Mohamed A; Pillai, Saju; Warrier, Krishna Gopakumar

2013-04-07

A novel nanocomposite coating containing titania, silica and lanthanum phosphate prepared through an all aqueous sol-gel route exhibits excellent self-cleaning ability arising from the synergistic effect of the constituents in the nanocomposite. A highly stable titania-silica-lanthanum phosphate nanocomposite sol having particle size in the range of 30-50 nm has been synthesized starting from a titanyl sulphate precursor, which was further used for the development of photocatalytically active composite coatings on glass. The coatings prepared by the dip coating technique as well as the nanocomposite powders are heat treated and characterized further for their morphology and multifunctionality. The nanocomposite containing 1.5 wt% LaPO4 has shown a surface area as high as 138 m(2) g(-1) and a methylene blue degradation efficiency of 94% in two hours of UV exposure. The composite coating has shown very good homogeneity evidenced by transparency as high as 99.5% and low wetting behaviour. The present novel approach for energy conserving, aqueous derived, self-cleaning coatings may be suitable for large scale industrial applications.

Preparation and Properties of Nanocomposites from Pristine and Modified SWCNTs of Comparable Average Aspect Ratios

NASA Technical Reports Server (NTRS)

Smith, Joseph G.; Delozier, Donavon M.; Watson, Kent A.; Connell, John W.; Bekyarova, E.; Haddon, R.; Yu, A.

2008-01-01

Low color, flexible, space-durable polyimide films with inherent and robust electrical conductivity to dissipate electrostatic charge (ESC) have been under investigation as part of a materials development activity for future NASA space missions. The use of single-walled carbon nanotubes (SWCNTs) is one means to achieving this goal. Even though the concentration of SWCNTs needed to achieve ESC dissipation is typically low, it is dependent upon purity, size, dispersion, and functionalization. In this study, SWCNTs prepared by the electric arc discharge method were used to synthesize nanocomposites using the LaRC(TradeMark) CP2 backbone as the matrix. Pristine and functionalized SWCNTs were mixed with an alkoxysilane terminated amide acid of LaRC(TradeMark) CP2 and the soluble imide form of the polymer and the resultant nanocomposites evaluated for mechanical, thermal, and electrical properties. Due to the preparative conditions for the pristine and functionalized SWCNTs, the average aspect ratio for both was comparable. This permitted the assessment of SWCNT functionalization with respect to various interactions (e.g. van der Waals, hydrogen bonding, covalent bond formation, etc.) with the matrix and the macroscopic effects upon nanocomposite properties. The results of this study are described herein.

Hydrothermal synthesis of graphene/nickel oxide nanocomposites used as the electrode for supercapacitors.

PubMed

Zhou, Zhongnian; Ni, Haifang; Fan, Li-Zhen

2014-07-01

Graphene (GR)-based nanocomposites with different mass ratios of NiO and GR are prepared via hydrothermal method using Ni(NO3)2 as the origin of nickel and urea as the hydrolysis-controlling agent. The morphology and electrochemical performance of the GR/NiO nanocomposites are closely associated with the mass ratios of GR to NiO. The chemical composition and morphology of the composites together with the pure GR and NiO are characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). It is found that the GR sheets and NiO particles form uniform nanocomposites with the NiO particles absorbed on the GR surface. A specific capacitance of 384 F g(-1) at a current density of 0.1 A g(-1) is achieved when the coating amount of NiO is up to 74 wt%. In addition, the attenuation of the specific capacitance is less than 6% after 500 cycles, indicating such nanocomposite has excellent cycling performance.

Characterization of silver/polystyrene nanocomposites prepared by in situ bulk radical polymerization

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

Vukoje, Ivana D., E-mail: ivanav@vinca.rs; Vodnik, Vesna V., E-mail: vodves@vinca.rs; Džunuzović, Jasna V., E-mail: jasnav2002@googlemail.com

2014-01-01

Graphical abstract: - Highlights: • Synthesis and characterization of polystyrene nanocomposites based on Ag nanoparticles. • The glass transition temperature decreased in nanocomposites with respect to the pure polymer. • Resistance of the polymer to thermal degradation enhanced with Ag nanoparticles content. - Abstract: Nanocomposites (NCs) with different content of silver nanoparticles (Ag NPs) embeded in polystyrene (PS) matrix were prepared by in situ bulk radical polymerization. The nearly monodisperse Ag NPs protected with oleylamine were synthesized via organic solvo-thermal method and further used as a filler. The as-prepared spherical Ag NPs with diameter of 7.0 ± 1.5 nm weremore » well dispersed in the PS matrix. The structural properties of the resulting Ag/PS NCs were characterized by transmission electron microscope (TEM) and Fourier transform infrared (FTIR) spectroscopy, while optical properties were characterized using optical absorption measurements. The gel permeation chromatography (GPC) measurements showed that the presence of Ag NPs stabilized with oleylamine has no influence on the molecular weight and polydispersity of the PS matrix. The influence of silver content on the thermal properties of Ag/PS NCs was investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicated that resistance of PS to thermal degradation was improved upon incorporation of Ag NPs. The Ag/PS NCs have lower glass transition temperatures than neat PS because loosely packed oleylamine molecules at the interface caused the increase of free volume and chain segments mobility near the surface of Ag NPs.« less

Size-dependent cytotoxicity and inflammatory responses of PEGylated silica-iron oxide nanocomposite size series

NASA Astrophysics Data System (ADS)

Injumpa, Wishulada; Ritprajak, Patcharee; Insin, Numpon

2017-04-01

Iron oxides nanoparticles have been utilized in biological systems and biomedical applications for many years because they are relatively safe and stable comparing to other magnetic nanomaterials. In some applications, iron oxide nanoparticles were modified with silica in order to be more stable in biological systems and able to be functionalized with various functional groups. Moreover, poly(ethylene glycol) (PEG) was one on the most used polymer to graft onto the nanoparticles in order to increase their biocompatibility, dispersibility and stability in aqueous solutions. Therefore, the nanocomposites comprising iron oxide nanoparticles, silica, and PEG could become multifunctional carriers combining superparamagnetic character, multi-functionality and high stability in biological environments. Herein, we reported the preparation of the nanocomposites and effects of their sizes on cytotoxicity and inflammatory responses. The PEGylated silica-iron oxide nanocomposites were prepared by coating of poly(poly(ethylene glycol) monomethyl ether methacrylate) (PPEGMA) on magnetic nanoparticle-silica nanocomposites via Atom Transfer Radical Polymerization (ATRP). The iron oxide nanoparticles were synthesized using a thermal decomposition method. The silica shells were then coated on iron oxides nanoparticles using reverse microemulsion and sol-gel methods. The size series of the nanocomposites with the diameter of 24.86±4.38, 45.24±5.00, 98.10±8.88 and 202.22±6.70 nm as measured using TEM were obtained. Thermogravimetric analysis (TGA) was used for the determination of % weight of PPEGMA on the nanocomposites showing the weight loss of ranging from 65% for smallest particles to 30% for largest particles. The various sizes (20, 40, 100, 200 nm) and concentrations (10, 100, 1000 μg/mL) of the nanocomposites were tested for their cytotoxicity in fibroblast and macrophage cell lines using MTT assay. The different sizes did not affect cell viability of fibroblast, albeit

Functional biocompatible magnetite-cellulose nanocomposite fibrous networks: Characterization by fourier transformed infrared spectroscopy, X-ray powder diffraction and field emission scanning electron microscopy analysis.

PubMed

Habibi, Neda

2015-02-05

The preparation and characterization of functional biocompatible magnetite-cellulose nano-composite fibrous material is described. Magnetite-cellulose nano-composite was prepared by a combination of the solution-based formation of magnetic nano-particles and subsequent coating with amino celluloses. Characterization was accomplished using X-ray powder diffraction (XRD), fourier transformed infrared (FTIR) and field emission scanning electron microscopy (FESEM) analysis. The peaks of Fe3O4 in the XRD pattern of nanocomposite confirm existence of the nanoparticles in the amino cellulose matrix. Magnetite-cellulose particles exhibit an average diameter of roughly 33nm as demonstrated by field emission scanning electron microscopy. Magnetite nanoparticles were irregular spheres dispersed in the cellulose matrix. The vibration corresponding to the NCH3 functional group about 2850cm(-1) is assigned in the FTIR spectra. Functionalized magnetite-cellulose nano-composite polymers have a potential range of application as targeted drug delivery system in biomedical field. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation and characterization of polymeric nanocomposite films for application as protective coatings

NASA Astrophysics Data System (ADS)

Gagliardi, S.; Rondino, F.; D'Erme, C.; Persia, F.; Menchini, F.; Santarelli, M. L.; Paulke, B.-R.; Enayati, A. L.; Falconieri, M.

2017-08-01

Addiction of ceramic nanoparticles to acrylic polymers provides a simple and effective means to produce paints with important properties, such as mechanical resistance and tailored wettability, even though for optimal performances, an engineered nanoparticle distribution would be desirable. In this paper we report on the realization and on the morphological and functional characterization of nanocomposites where the nanophase is distributed on the surface of acrylic polymer films, in order to enhance the expression of surface-related properties. To this aim, commercial titanium oxide and silicon oxide nanopowders were dispersed in water and the suspensions were air-sprayed on polymeric films prepared by paint brushing, thus producing a nanostructured ceramic surface coating. Control of the pH of suspensions and acrylic acid functionalization of the surface of titania were used together with high power ultrasonic treatments in order to control dimension of the aggregates in the sprayed suspensions. Optical microscopy, mechanical profilometry, and atomic force microscopy were used to characterize the nanocomposite surface morphology and correlate it to the coating functional properties, evaluated through mechanical abrasion tests and contact angle measurements; also, colorimetry on coated stones was performed in order to test the impact of the coatings on the aesthetical appearance and their photostability under UV irradiation. Results show that the nanostructured ceramic layer slightly improves the resistance of coatings to mechanical abrasion in case of polymer films prepared from latexes. The nanocomposite surface layer does not affect the wettability of the polymer, which remained slightly hydrophilic; this behavior is likely due to inadequate distribution of the nanophase. On the other hand UV-induced superhydrophilicity was observed when the concentration of surface titania nanoparticles is about 0.6 mg/cm2. Colorimetric analysis on historical and Carrara

ZnO/TiO2 nanocomposite rods synthesized by microwave-assisted method for humidity sensor application

NASA Astrophysics Data System (ADS)

Ashok, CH.; Venkateswara Rao, K.

2014-12-01

The nanocomposite rods shows well known properties compared with nano structured materials for various applications like light-emitting diodes, electron field emitters, solar cells, optoelectronics, sensors, transparent conductors and fabrication of nano devices. Present paper investigates the properties of ZnO/TiO2 nanocomposite rods. The bi component of ZnO/TiO2 nanocomposite rods was synthesized by microwave-assisted method which is very simple, rapid and uniform in heating. The frequency of microwaves 2.45 GHz was used and temperature maintained 180 °C. Zinc acetate and titanium isopropoxide precursors were used in the preparation. The obtained ZnO/TiO2 nanocomposite rods were annealed at 500 °C and 600 °C. ZnO/TiO2 nanocomposite rods have been characterized by X-ray Diffraction (XRD) for average crystallite size and phase of the composite material, Particle Size Analyser (PSA) for average particle size, Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) for morphology study, Energy Dispersive X-ray Spectrometry (EDX) for elemental analysis, and Thermal Gravimetric and Differential Thermal Analysis (TG-DTA) for thermal property.

Pulse electrodeposition of self-lubricating Ni-W/PTFE nanocomposite coatings on mild steel surface

NASA Astrophysics Data System (ADS)

Sangeetha, S.; Kalaignan, G. Paruthimal; Anthuvan, J. Tennis

2015-12-01

Ni-W/PTFE nanocomposite coatings with various contents of PTFE (polytetafluoroethylene) particles were prepared by pulse current (PC) electrodeposition from the Ni-W plating bath containing self lubricant PTFE particles to be co-deposited. Co-deposited PTFE particulates were uniformly distributed in the Ni-W alloy matrix. The coatings were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), X-ray Diffractometry (XRD) and Vicker's micro hardness tester. Tafel Polarization and electrochemical Impedance methods were used to evaluate the corrosion resistance behaviour of the nanocomposite coatings in 3.5% NaCl solution. It was found that, the Ni-W/PTFE nanocomposite coating has better corrosion resistance than the Ni-W alloy coating. Surface roughness and friction coefficient of the coated samples were assessed by Mitutoyo Surftest SJ-310 (ISO1997) and Scratch tester TR-101-M4 respectively. The contact angle (CA) of a water droplet on the surface of nanocomposite coating was measured by Optical Contact Goniometry (OCA 35). These results indicated that, the addition of PTFE in the Ni-W alloy matrix has resulted moderate microhardness, smooth surface, less friction coefficient, excellent water repellency and enhanced corrosion resistance of the nanocomposite coatings.

Preparation of silver-hydroyapatite/PVA nanocomposites: Giant dielectric material for industrial and clinical applications

NASA Astrophysics Data System (ADS)

Uddin, Md Jamal; Middya, T. R.; Chaudhuri, B. K.

2015-02-01

Pure hydroxyappatite Ca10(PO4)6(OH)2 (or HAP) was prepared from eggshell and potassium dihydrogen phosphate (KH2PO4) by a simple self-chemical reaction method. The clean eggshell was heated at 800 °C in air giving the source of CaO. Appropriate amount of CaO was dissolved in KH2PO4 solution at 37°C for few days. The PH value decreases with increasing the duration of preparation of HAP. Silver nanoparticles derived from silver nitrate solution using black tea leaf extract had been introduced to hydroxyapatite due to its biocompatibility. The unique size- dependent properties of nanomaterials make them superior and indispensable. In this work, hydroxyapatite-silver nanoparticles/polyvinyl alcohol (PVA) composites with 4 different concentrations of hydroxyapatite (1-4 wt %) were prepared by bio-reduction method. Several techniques like XRD and SEM were used to characterize the prepared samples. Frequency dependent capacitance and conductance of the samples were measured using an impedance analyzer. The results showed a remarkable increase in dielectric permittivity (~5117) with low loss (~0.23) at1000 HZ and room temperature (300K) for 4wt% Hydroxapatie-Silver/PVA nanocomposite. Such nanocomposite might be directly applied in manufacturing clinical devices and also for embedding capacitor applications.

Weathering of a carbon nanotube/epoxy nanocomposite under UV light and in water bath: impact on abraded particles.

PubMed

Schlagenhauf, Lukas; Kianfar, Bahareh; Buerki-Thurnherr, Tina; Kuo, Yu-Ying; Wichser, Adrian; Nüesch, Frank; Wick, Peter; Wang, Jing

2015-11-28

Weathering processes can influence the surface properties of composites with incorporated nanoparticles. These changes may affect the release behavior of nanoparticles when an abrasion process is applied. Therefore, the influence of two different weathering processes, immersion in water and exposure to UV light, on the properties of abraded particles from a carbon nanotube (CNT)/epoxy nanocomposite was investigated. The investigation included the measurement of the weathering impact on the surface chemistry of the exposed samples, the particle size of abraded particles, the quantity of exposed CNTs in the respirable part of the abraded particles, and the toxicity of abraded particles, measured by in vitro toxicity tests using the THP-1 monocyte-derived macrophages. The results showed that weathering by immersion in water had no influence on the properties of abraded particles. The exposure to UV light caused a degradation of the epoxy on the surface, followed by delamination of an approx. 2.5 μm thick layer. An increased quantity of exposed CNTs in abraded particles was not found; on the contrary, longer UV exposure times decreased the released fraction of CNTs from 0.6% to 0.4%. The toxicity tests revealed that abraded particles from the nanocomposites did not induce additional acute cytotoxic effects compared to particles from the neat epoxy.

Osteogenic activity and antibacterial effect of zinc oxide/carboxylated graphene oxide nanocomposites: Preparation and in vitro evaluation.

PubMed

Chen, Junyu; Zhang, Xin; Cai, He; Chen, Zhiqiang; Wang, Tong; Jia, Lingling; Wang, Jian; Wan, Qianbing; Pei, Xibo

2016-11-01

The aim of this study was to prepare nanocomposites of carboxylated graphene oxide (GO-COOH) sheets decorated with zinc oxide (ZnO) nanoparticles (NPs) and investigate their advantages in the field of bone tissue engineering. First, ZnO/GO-COOH nanocomposites were synthesized by facile reactions, including the carboxylation of graphene oxide (GO) and the nucleation of ZnO on GO-COOH sheets. The synthesized ZnO/GO-COOH nanocomposites were then characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectra, and transmission electron microscopy (TEM). The biocompatibility, osteogenic activity and antibacterial effect of ZnO/GO-COOH nanocomposites were further investigated. In the nanocomposites, ZnO nanoparticles with a size of approximately 12nm were uniformly decorated on GO-COOH sheets. Compared with GO-COOH and the control group, ZnO/GO-COOH nanocomposites significantly enhanced ALP activity, osteocalcin production and extracellular matrix mineralization as well as up-regulated osteogenic-related genes (ALP, OCN, and Runx2) in MG63 osteoblast-like cells. Moreover, ZnO/GO-COOH nanocomposites had an antibacterial effect against Streptococcus mutans. These results indicated that ZnO/GO-COOH nanocomposites exhibited both osteogenic activity and antibacterial effect and had great potential for designing new biomaterials in the field of bone tissue engineering. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation of nanocomposite γ-Al2O3/polyethylene separator crosslinked by electron beam irradiation for lithium secondary battery

NASA Astrophysics Data System (ADS)

Nho, Young-Chang; Sohn, Joon-Yong; Shin, Junhwa; Park, Jong-Seok; Lim, Yoon-Mook; Kang, Phil-Hyun

2017-03-01

Although micro-porous membranes made of polyethylene (PE) offer excellent mechanical strength and chemical stability, they exhibit large thermal shrinkage at high temperature, which causes a short circuit between positive and negative electrodes in cases of unusual heat generation. We tried to develop a new technology to reduce the thermal shrinkage of PE separators by introducing γ-Al2O3 particles treated with coupling agent on PE separators. Nanocomposite γ-Al2O3/PE separators were prepared by the dip coating of polyethylene(PE) separators in γ-Al2O3/poly(vinylidenefluoride-hexafluoropropylene) (PVDF-HFP)/crosslinker (1,3,5-trially-1,3,5-triazine-2,4,6(1 H,3 H,5 H)-trione (TTT) solution with humidity control followed by electron beam irradiation. γ-Al2O3/PVDF-HFP/TTT (95/5/2)-coated PE separator showed the highest electrolyte uptake (157%) and ionic conductivity (1.3 mS/cm). On the basis of the thermal shrinkage test, the nanocomposite γ-Al2O3/PE separators containing TTT irradiated by electron beam exhibited a higher thermal resistance. Moreover, a linear sweep voltammetry test showed that the irradiated nanocomposite γ-Al2O3/PE separators have electrochemical stabilities of up to 5.0 V. In a battery performance test, the coin cell assembled with γ-Al2O3/PVDF-HFP/TTT-coated PE separator showed excellent discharge cycle performance.

Omega-3 PUFA concentration by a novel PVDF nano-composite membrane filled with nano-porous silica particles.

PubMed

Ghasemian, Samaneh; Sahari, Mohammad Ali; Barzegar, Mohsen; Ahmadi Gavlighi, Hasan

2017-09-01

In this study, polyvinylidene fluoride (PVDF) and nano-porous silica particle were used to fabricate an asymmetric nano-composite membrane. Silica particles enhanced the thermal stability of PVDF/SiO 2 membranes; increasing the decomposition temperature from 371°C to 408°C. Cross sectional morphology showed that silica particles were dispersed in polymer matrix uniformly. However, particle agglomeration was found at higher loading of silica (i.e., 20 by weight%). The separation performance of nano-composite membranes was also evaluated using the omega-3 polyunsaturated fatty acids (PUFA) concentration at a temperature and pressure of 30°C and 4bar, respectively. Silica particle increased the omega-3PUFA concentration from 34.8 by weight% in neat PVDF to 53.9 by weight% in PVDF with 15 by weight% of silica. Moreover, PVDF/SiO 2 nano-composite membranes exhibited enhanced anti-fouling property compared to neat PVDF membrane. Fouling mechanism analysis revealed that complete pore blocking was the predominant mechanism occurring in oil filtration. The concentration of omega-3 polyunsaturated fatty acids (PUFA) is important in the oil industries. While the current methods demand high energy consumptions in concentrating the omega-3, membrane separation technology offers noticeable advantages in producing pure omega-3 PUFA. Moreover, concentrating omega-3 via membrane separation produces products in the triacylglycerol form which possess better oxidative stability. In this work, the detailed mechanisms of fouling which limits the performance of membrane separation were investigated. Incorporating silica particles to polymeric membrane resulted in the formation of mixed matrix membrane with improved anti-fouling behaviour compared to the neat polymeric membrane. Hence, the industrial potential of membrane processing to concentrate omega-3 fatty acids is enhanced. Copyright © 2017. Published by Elsevier Ltd.

Impact of Plasma Surface Treatment on Bamboo Charcoal/silver Nanocomposite

NASA Astrophysics Data System (ADS)

Vignesh, K.; Vijayalakshmi, K. A.; Karthikeyan, N.

2016-10-01

Bamboo charcoal (BC) accompanied silver (Ag) nanocomposite is synthesized through sol-gel method. The produced BC/Ag nanocomposite was surface modified by air and oxygen plasma treatments. Silver ions (Ag+) will serve to improve the antibacterial activity as well as the surface area of BC. Plasma treatment has improved the surface functional groups, crystalline intensity and antibacterial activity of the prepared nanocomposite. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies show that Ag nanoparticles have good agreement with BC and the particle size has a mean diameter of 20-40nm. We observe the carboxyl functional groups in Fourier transform infrared spectroscopy (FTIR) after the oxygen plasma treatment. Moreover surface area and adsorption were analyzed by using the Brunauer, Emmett and Teller (BET) surface area (SBET) and UV-Vis spectroscopy.

Sulfonated Styrene-(ethylene-co-butylene)-styrene/Montmorillonite Clay Nanocomposites: Synthesis, Morphology, and Properties

PubMed Central

2008-01-01

Sulfonated styrene-(ethylene-butylene)-styrene triblock copolymer (SSEBS) was synthesized by reaction of acetyl sulfate with SEBS. SSESB-clay nanocomposites were then prepared from hydrophilic Na-montmorillonite (MT) and organically (quaternary amine) modified hydrophobic nanoclay (OMT) at very low loading. SEBS did not show improvement in properties with MT-based nanocomposites. On sulfonation (3 and 6 weight%) of SEBS, hydrophilic MT clay-based nanocomposites exhibited better mechanical, dynamic mechanical, and thermal properties, and also controlled water–methanol mixture uptake and permeation and AC resistance. Microstructure determined by X-ray diffraction, atomic force microscopy, and transmission electron microscopy due to better dispersion of MT nanoclay particles and interaction of MT with SSEBS matrix was responsible for this effect. The resulting nanocomposites have potential as proton transfer membranes for Fuel Cell applications.

Advances in rubber/halloysite nanotubes nanocomposites.

PubMed

Jia, Zhixin; Guo, Baochun; Jia, Demin

2014-02-01

The research advances in rubber/halloysite nanotubes (rubber/HNTs) nanocomposites are reviewed. HNTs are environmentally-friendly natural nanomaterials, which could be used to prepare the rubber-based nanocomposites with high performance and low cost. Unmodified HNTs could be adopted to prepare the rubber/HNTs composites with improved mechanical properties, however, the rubber/HNTs nanocomposites with fine morphology and excellent properties were chiefly prepared with various modifiers by in situ mixing method. A series of rubber/HNTs nanocomposites containing several rubbers (SBR, NR, xSBR, NBR, PU) and different modifiers (ENR, RH, Si69, SA, MAA, ILs) have been investigated. The results showed that all the rubber/HNTs nanocomposites achieved strong interfacial interaction via interfacial covalent bonds, hydrogen bonds or multiple interactions, realized significantly improved dispersion of HNTs at nanoscale and exhibited excellent mechanical performances and other properties.

Polymer-ceramic nanocomposites for applications in the bone surgery

NASA Astrophysics Data System (ADS)

Stodolak, E.; Gadomska, K.; Lacz, A.; Bogun, M.

2009-01-01

The subject of this work was preparation and investigation of properties of a nanocomposite material based on polymer matrix modified with nanometric silica particles (SiO2). The composite matrix consisted of resorbable P(L/DL)LA polymer with certified biocompatibility. Nanometric silica was introduced into the matrix by means of ultrasonic homogenisation and/or mechanical stirring. The silica was introduced directly e.g. as nanoparticles or inside calcium alginate fibres which contained 3 wt.% of amorphous SiO2. Proper dispersion of nano-filliers was confirmed by means of thermal analysis (TG/DTA, DSC). It was observed, that the presence of inorganic nanoparticles influenced several surface parameters of the nanocomposites i.e. hydrophility (a decrease of surface energy) and topography (both in micro- and nano-scale). Additionally, the nanocomposites exhibited enhanced mechanical properties (Young's modulus, tensile strength) compared to the pure polymer. The nanocomposites were bioactive materials (SBF/3 days/37oC). Biological tests (MTT test) showed a good viability of human osteoblasts (hFOB 1.19) in contact with the nanocomposites surface. Results of preliminary biological tests carried out with the use of mother cells extracted from human bone marrow showed that the nanocomposites may provide differenation of bone cells.

Photoinactivation of bacteria by using Fe-doped TiO2-MWCNTs nanocomposites.

PubMed

Koli, Valmiki B; Delekar, Sagar D; Pawar, Shivaji H

2016-12-01

In this study, nanocomposites of Fe-doped TiO 2 with multi-walled carbon nanotubes (0.1- 0.5 wt. %) were prepared by using sol-gel method. The structural and morphological analysis were carried out with using X-ray diffraction pattern and transmission electron microscopy, which confirm the presence of pure anatase phase and particle sizes in the range 15-20 nm. X-ray photoelectron spectroscopy was used to determine the surface compositions of the nanocomposites. UV-vis diffuse reflectance spectra confirm redshift in the optical absorption edge of nanocomposites with increasing amount of multi-walled carbon nanotubes. Nanocomposites show photoinactivation against gram-positive Bacillus subtilis as well as gram-negative Pseudomonas aeruginosa. Fe-TiO 2 -multi-walled carbon nanotubes (0.5 wt. %) nanocomposites show higher photoinactivation capability as compared with other nanocomposites. The photoluminescence study reveals that the Fe-TiO 2 -multi-walled carbon nanotubes nanocomposites are capable to generate higher rate of reactive oxygen species species than that of other nanocomposites. Our experimental results demonstrated that the Fe-TiO 2 -multi-walled carbon nanotubes nanocomposites act as efficient antibacterial agents against a wide range of microorganisms to prevent and control the persistence and spreading of bacterial infections.

Preparation and Properties of Ethylene Vinyl Acetate Copolymer/Silica Nanocomposites in Presence of EVA-g-Acrylic Acid.

PubMed

Tham, Do Quang; Tuan, Vu Manh; Thanh, Dinh Thi Mai; Chinh, Nguyen Thuy; Giang, Nguyen Vu; Trang, Nguyen Thi Thu; Hang, To Thi Xuan; Huong, Ho Thu; Dung, Nguyen Thi Kim; Hoang, Thai

2015-04-01

Here we report a facile approach to enhance the dispersibility of ethylene vinyl acetate copolymer (EVA)/silica nanocomposites (for the EVA/silica nanocomposites and interaction between silica nanoparticles (nanosilica) and EVA by adding EVA-g-acrylic acid (EVAgAA) as a compatibilizer, which was formed by grafting acrylic acid onto EVA chains with the aid of dicumyl peroxide). The above nanocomposites with and without EVAgAA were prepared by melt mixing in a Haake intermixer with different contents of silica and EVAgAA. Their structure and morphology were characterized by Fourier transform infra-red (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), and the mechanical, rheological, dielectrical, and flammability properties of the nanocomposites were also investigated. The FT-IR spectra of the nanocomposites confirmed the formation of hydrogen bonds between the surface silanol groups of nanosilica and C=O groups of EVA and/or EVAgAA. The presence of EVAgAA remarkably increased the intensity of hydrogen bonding between nanosilica and EVA which not only enhanced the dispersion of nanosilica in EVA matrix but also increased the mechanical, viscosity and storage modulus of EVA/silica nanocomposites. In addition, the flammability of EVA/silica nanocomposites is also significantly reduced after the functionalization with EVAgAA. However, the mechanical properties of EVA/silica nanocomposites tended to level off when its content was above 1.5 wt.%. It has also been found that the dielectric constant value of the EVA/EVAgAA/silica nanocomposites is much lower than that of the EVA/silica nanocomposites, which is another evidence of the hydrogen bonding formation between EVAgAA and nanosilica.

Synthesis of Co/MFe(2)O(4) (M = Fe, Mn) Core/Shell Nanocomposite Particles.

PubMed

Peng, Sheng; Xie, Jin; Sun, Shouheng

2008-01-01

Monodispersed cobalt nanoparticles (NPs) with controllable size (8-14 nm) have been synthesized using thermal decomposition of dicobaltoctacarbonyl in organic solvent. The as-synthesized high magnetic moment (125 emu/g) Co NPs are dispersible in various organic solvents, and can be easily transferred into aqueous phase by surface modification using phospholipids. However, the modified hydrophilic Co NPs are not stable as they are quickly oxidized, agglomerated in buffer. Co NPs are stabilized by coating the MFe(2)O(4) (M = Fe, Mn) ferrite shell. Core/shell structured bimagnetic Co/MFe(2)O(4) nanocomposites are prepared with tunable shell thickness (1-5 nm). The Co/MFe(2)O(4) nanocomposites retain the high magnetic moment density from the Co core, while gaining chemical and magnetic stability from the ferrite shell. Comparing to Co NPs, the nanocomposites show much enhanced stability in buffer solution at elevated temperatures, making them promising for biomedical applications.

Synthesis and Characterization of Hydroxyapatite/Fullerenol Nanocomposites.

PubMed

Djordjevic, Aleksandar; Ignjatovic, Nenad; Seke, Mariana; Jovic, Danica; Uskokovic, Dragan; Rakocevic, Zlatko

2015-02-01

Fullerenols are polyhydroxylated, water soluble derivatives of fullerene C60, with potential application in medicine as diagnostic agents, antioxidants or nano drug carriers. This paper describes synthesis and physical characterization of a new nanocomposite hydroxyapatite/fullerenol. Surface of the nanocomposite hydroxyapatite/fullerenol is inhomogeneous with the diameter of the particles in the range from 100 nm to 350 nm. The ζ potential of this nanocomposite is ten times lower when compared to hydroxyapatite. Surface phosphate groups of hydroxyapatite are prone to forming hydrogen bonds, when in close contact with hydroxyl groups, which could lead to formation of hydrogen bonds between hydroxyapatite and hydroxyl groups of fullerenol. The surface of hydroxyapatite particles (-2.5 mV) was modified by fullerenol particles, as confirmed by the obtained ζ potential value of the nanocomposite biomaterial hydroxyapatite/fullerenol (-25.0 mV). Keywords: Hydroxyapatite, Fullerenol, Nanocomposite, Surface Analysis.

Ultrasonically assisted single screw extrusion, film blowing and film casting of LLDPE/clay and PA6/clay nanocomposites

NASA Astrophysics Data System (ADS)

Niknezhad, Setareh

The major objective of this study was to investigate the effect of ultrasonic treatment on the dispersion of modified clay particles in LLDPE and PA6 matrices and the final properties of nanocomposites. LLDPE and PA6 are two polymers that are widely used in packaging industry. Blown and cast films were manufactured from the prepared nanocomposites. To achieve one step film processing, an online ultrasonic film casting was developed. Ultrasonic waves caused high-energy mixing and dispersion due to the acoustic cavitation, causing the clay agglomorates to separate into individual platelets in polymer matrix. Ultrasonic waves also broke down the polymer molecular chains reducing viscosity of the melt, facilating dispersion of the clay platelets throughout the matrix. Ultrasound also led to a breakage of the clay platelets reducing the particle size and improving their distribution. Clay particles acted as a heterogenous nucleation agent generating smaller size polymer crystals. In turn, these improved different properties including mechanical properties, oxygen permeability and transparency of films. In LLDPE/clay 20A nanocomposites, the effect of ultrasound was more obvious at higher clay loadings. Exfoliated structure for ultrasonically treated nanocomposites containing 2.5, 5 and 7.5 wt% of clay 20A and highly intercalated structure for ultrasonically treated nanocomposites containing 10 wt% of clay 20A were achieved. However, in blown films, the exfoliated structure transferred to the intercalated structure due to the addition of more shear and thermal degradation of surfactants of the clay particles. While, manufacturing cast films using the new developed online ultrasonic cast film machine revealed the exfoliated structure with ultrasonic treatment till 7.5 wt% of clay loadings. Cast films of nanocomposites containing 5 wt% of clay loadings were also prepared with addition of different compatibilizers. The compatibilizer containing higher amount of grafted

Preparation and characterization of Chitosan/Konjac glucomannan/CdS nanocomposite film with low infrared emissivity

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

Zhang, Feng-Ying; Zhou, Yu-Ming, E-mail: fchem@seu.edu.cn; Sun, Yan-qing

Novel organic-inorganic nanocomposite films were prepared with Chitosan (CS), Konjac glucomannan (KGM) and CdS by one-step synthesis. As-prepared films were characterized by IR spectra, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and infrared emissometer (IR). The results indicated that grown CdS dendrites were formed with reaction time of 12 h for Cd{sup 2+} and CS/KGM, and were well dispersed in CS/KGM with an average diameter of 40 nm. The CS/KGM/CdS nanocomposite films had significantly low infrared emissivity. When the mole ratio of CdS to summation of CS and KGM construction units was 1.0 with CdS size of 10-20 nm,more » the film got the lowest infrared emissivity value of 0.011, which could be attributed to the strong synergism effect existing between CS/KGM and CdS dendrites.« less

Preparation and Characterization of WS2@SiO2 and WS2@PANI Core-Shell Nanocomposites

PubMed Central

Sade, Hagit

2018-01-01

Two tungsten disulfide (WS2)-based core-shell nanocomposites were fabricated using readily available reagents and simple procedures. The surface was pre-treated with a surfactant couple in a layer-by-layer approach, enabling good dispersion of the WS2 nanostructures in aqueous media and providing a template for the polymerization of a silica (SiO2) shell. After a Stöber-like reaction, a conformal silica coating was achieved. Inspired by the resulting nanocomposite, a second one was prepared by reacting the surfactant-modified WS2 nanostructures with aniline and an oxidizing agent in an aqueous medium. Here too, a conformal coating of polyaniline (PANI) was obtained, giving a WS2@PANI nanocomposite. Both nanocomposites were analyzed by electron microscopy, energy dispersive X-ray spectroscopy (EDS) and FTIR, verifying the core-shell structure and the character of shells. The silica shell was amorphous and mesoporous and the surface area of the composite increases with shell thickness. Polyaniline shells slightly differ in their morphologies dependent on the acid used in the polymerization process and are amorphous like the silica shell. Electron paramagnetic resonance (EPR) spectroscopy of the WS2@PANI nanocomposite showed variation between bulk PANI and the PANI shell. These two nanocomposites have great potential to expand the use of transition metals dichalcogenides (TMDCs) for new applications in different fields. PMID:29534426

One-step Preparation of graphene oxide/polypyrrole magnetic nanocomposite and its application in the removal of methylene blue dye from aqueous solution

NASA Astrophysics Data System (ADS)

Afzali Nezhad, Ali; Alimoradi, Mohammad; Ramezani, Majid

2018-02-01

Herein, we report a novel one-step strategy to construct magnetic nanocomposite (polypyrrole/GO@Fe3O4) via a simple and effective chemical method. First, the GO nanosheets were fabricated through modified Hummers method, and then, the Fe3O4 nanoparticles and polypyrrole were decorated on surface of the GO nanosheets by coprecipitation of ferrous salts and pyrrole monomer in GO suspension. The ferric chloride could act both as oxidizing agent and also for preparation of magnetic Fe3O4 nanoparticles. The prepared nanomaterials were characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy, x-ray diffraction, and TGA measurements. The prepared magnetic nanocomposite had a much higher thermal stability than pure graphene oxide. The magnetic nanocomposite has been employed as adsorbent for the magnetic separation of Methylene Blue dye from water. The adsorption test of Methylene Blue (MB) demonstrates that it only takes few minutes for MB to attain equilibrium. The effect of experimental conditions such as contact time and pH as well as kinetic and isotherm of adsorption of MB dye was also studied. The highest adsorption capacity for MB was 323.2 mg g-1. The pH optimization experiments showed that pH = 8 is optimum pH for investigation of MB dye adsorption. It is also must be mentioned that most of adsorption of MB dye achieved within first 10 min of exposure to MB dye which indicated the strong interaction between dye molecules and adsorbent and high rate of adsorption of dye on magnetic nanocomposite. Adsorption procedure of dye were fitted well by pseudo-second-order kinetic and Langmuir isotherm models. The cycling reusability of magnetic nanocomposite showed comparable values to other studies. Results showed that the prepared new magnetic nanocomposite has great potential application for removal of organic dyes from polluted water.

Preparation, characterization and dye adsorption of Au nanoparticles/ZnAl layered double oxides nanocomposites

NASA Astrophysics Data System (ADS)

Zhang, Yu Xin; Hao, Xiao Dong; Kuang, Min; Zhao, Han; Wen, Zhong Quan

2013-10-01

In this work, Au/ZnAl-layer double oxides (LDO) nanocomposties were prepared through a facile calcination process of AuCl4- intercalated ZnAl-layered double hydroxides (LDHs) nanocomposites. The morphology and crystal structure of these nanocomposites were characterized by Scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and N2 sorption analysis. By tailoring the process parameter, such as calcination temperature, heating time and the component composition, the adsorption properties of methyl orange (MO) on the Au/ZnAl-LDO nanocomposites were investigated in this work. In a typical adsorption process, it was found that 0.985 mg of MO (0.01 g L-1, 100 mL, 1 mg of MO in total) can be removed in 60 min by utilizing only 2.5 mg of Au/ZnAl-LDO (Au content, 1%) as adsorbents. Our adsorption data obtained from the Langmuir model also gave good values of the determination coefficient, and the saturated adsorption capacity of Au/ZnAl-LDO nanocomposites for MO was found to be 627.51 mg/g under ambient condition (e.g., room temperature, 1 atm). In principle, these hybrid nanostructures with higher adsorption abilities could be very promising adsorbents for wastewater treatment.

A multifunctional magneto-fluorescent nanocomposite for visual recognition of targeted cancer cells

NASA Astrophysics Data System (ADS)

Acharya, Amitabha; Rawat, Kiran; Bhat, Kaisar Ahmad; Patial, Vikram; Padwad, Yogendra S.

2015-11-01

A multifunctional hybrid nanocomposite material of iron oxide nanoparticles and CdS quantum dots was synthesized by a direct amide coupling reaction. The prepared nanoparticles were characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic light scattering (DLS) and zeta potential studies. The TEM studies suggested that the sizes of the particles were in the range of 13.5 ± 1 nm. The energy dispersive x-ray (EDX) analysis confirmed the presence of Fe, Cd and S in the nanocomposites. To check the utility of this nanocomposite as a molecular imaging probe, these nanoparticles were further conjugated with folic acid. The folic acid conjugated nanocomposites were treated with rat glioma cells (C6, folic acid receptor over-expressing cell lines), human lung adenocarcinoma epithelial cells (A549, folic acid receptor negative cell lines) and normal mouse splenocytes for cell uptake and cytotoxicity studies. The nanoparticle internalization to C6 cells was confirmed by green fluorescence emission from these cells. Prussian blue staining studies suggested the intracellular presence of iron oxide. Further it was found that folic acid conjugated nanocomposites were significantly toxic to C6 cells only after 48 h but not to A549 cells or splenocytes. These studies indicated that the prepared nanocomposites have the potential to be used as delivery agent for magnetic and fluorescent materials towards folic acid receptor over-expressing cells and thus can find their application in the field of in vitro imaging diagnosis.

The preparation of nanosized polyethylene particles via novel heterogeneous non-metallocene catalyst (m-CH3PhO)TiCl3/CNTs/AlEt3

NASA Astrophysics Data System (ADS)

Wang, J.; Guo, J. P.; Yi, J. J.; Huang, Q. G.; Li, H. M.; Li, Y. F.; Gao, K. J.; Yang, W. T.

2014-08-01

This paper reports the preparation of coral-shaped topological morphology nascent polyethylene (PE) particles promoted by the novel heterogeneous non-metallocene catalyst (m-CH3PhO)TiCl3/carbon nanotubes (CNTs), with AlEt3 used as a cocatalyst. Scanning electron microscope (SEM), high resolution transmission electron microscope (HR-TEM) and inductively coupled plasma (ICP) emission spectroscopy were used to determine the morphology of the catalyst particles and the content of (m-CH3PhO)TiCl3. The carbon nanotube surface was treated with Grignard Reagent prior to reacting with (m-CH3PhO)TiCl3. The catalyst system could effectively catalyze ethylene polymerization and ethylene with 1- hexene copolymerization, the catalytic activity could reach up to 5.8 kg/((gTi)h). Morphology of the obtained polymer particles by SEM and HR-TEM technique revealed that the nascent polyethylene particles looked like coral shape in micro-size. The multiwalled carbon nanotubes (MWCNTs) supported catalysts polymerized ethylene to form polymer nanocomposite in situ. The microscopic examination of this nanocomposite revealed that carbon nanoparticles in PE matrix had a good distribution and the cryogenically fractured surface was ductile-like when polymerization time was 2 min.

Anisotropic silver nanoparticles as filler for the formation of hybrid nanocomposites

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

Vodnik, Vesna V., E-mail: vodves@vinca.rs; Šaponjić, Zoran, E-mail: saponjic@vinca.rs; Džunuzović, Jasna V., E-mail: jasnav2002@googlemail.com

2013-01-15

Graphical abstract: Display Omitted Highlights: ► Prismatic and plate-like Ag nanoparticles were used as a precursors for preparation Ag/poly(vinyl alcohol) nanocomposite films. ► Results showed that the degree of crystallinity of the polymer decreases with Ag nanoparticles content. ► The presence of Ag nanoparticles in PVA induces higher thermo-oxidative stability with respect to PVA. -- Abstract: Prismatic and plate-like silver nanoparticles (Ag NPs) were synthesized according to the seed-mediated method. These particles were used as precursors for preparation of homogenous, transparent and colored Ag/poly(vinyl alcohol) (PVA) nanocomposite films with different concentrations of Ag by solution-casting technique. Optical and structural characterizationmore » of these nanocomposites includes UV–visible spectroscopy, X-ray diffraction (XRD), FTIR spectroscopy and SEM measurements. Further, the effect of embedded nanoparticles on the thermal properties of the PVA matrix was studied. The value of the glass transition temperature of polymer is found to increase after embedding Ag NPs. Comparison of thermal properties of pure PVA and nanocomposite films showed that the thermo-oxidative stability of polymer slightly increased in the presence of Ag NPs. Furthermore, the effect of the Ag NPs on the crystallinity of polymer was also observed.« less

Polyaniline-CuO hybrid nanocomposite with enhanced electrical conductivity

NASA Astrophysics Data System (ADS)

de Souza, Vânia S.; da Frota, Hidembergue O.; Sanches, Edgar A.

2018-02-01

A hybrid nanocomposite based on a polymer matrix constituted of Polyaniline Emeraldine-salt form (PANI-ES) reinforced by copper oxide II (CuO) particles was obtained by in situ polymerization. Structural, morphological and electrical properties of the pure materials and nanocomposite form were investigated. The presence of CuO particles in the nanocomposite material affected the natural alignment of the polymer chains. XRD technique allowed the visualization of the polymer amorphization in the nanocomposite form, suggesting an interaction between both phases. The FTIR spectra confirmed this molecular interaction due to the blue shift of the characteristic absorption peaks of PANI-ES in the nanocomposite form. SEM images revealed that the polymer nanofiber morphology was no longer observed in the nanocomposite. The CuO spherical particles are randomly dispersed in the polymer matrix. The density functional theory plus the Coulomb interaction method revealed a charge transfer from PANI to CuO slab. Moreover, the density of states (DOS) has revealed that the nanocomposite behaves as a metal. In agreement, the electrical conductivity showed an increase of 60% in the nanocomposite material.

Stress development in particulate, nano-composite and polymeric coatings

NASA Astrophysics Data System (ADS)

Jindal, Karan

2009-12-01

The main goal of this research is to study the stress, structural and mechanical property development during the drying of particulate coatings, nano-composite coatings and VOC compliant refinish clearcoats. The results obtained during this research establish the mechanism for the stress development during drying in various coating systems. Coating stress was measured using a controlled environment stress apparatus based on cantilever deflection principle. The stress evolution in alumina coatings made of 0.4 mum size alumina particles was studied and the effect of a lateral drying was investigated. The stress does not develop until the later stages of drying. A peak stress was observed during drying and the peak stress originates due to the formation of pendular rings between the particles. Silica nanocomposite coatings were fabricated from suspension of nano sized silicon dioxide particles (20 nm) and polyvinyl alcohol (PVA) polymer. The stress in silica nano-composite goes through maximum as the amount of polymer in the coating increases. The highest final stress was found to be ˜ 110MPa at a PVA content of 60 wt%. Observations from SEM, nitrogen gas adsorption, camera imaging, and nano-indentation were also studied to correlate the coatings properties during drying to measured stress. A model VOC compliant two component (2K) acrylic-polyol refinish clearcoat was prepared to study the effects of a new additive on drying, curing, rheology and stress development at room temperature. Most of the drying of the low VOC coatings occurred before appreciable (20%) crosslinking. Tensile stress developed in the same timeframe as drying and then relaxed over a longer time scale. Model low VOC coatings prepared with the additive had higher peak stresses than those without the additive. In addition, rheological data showed that the additive resulted in greater viscosity buildup during drying.

Novel MnOOH–graphene nanocomposites: Preparation, characterization and electrochemical properties for supercapacitors

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

Mei, Jun; Zhang, Long, E-mail: zhanglongzhl@163.com

2015-01-15

In this paper, we report a simple and controlled synthesis of novel MnOOH–graphene nanocomposites with a one-step facile hydrothermal method. It is template-free and easy to reproduce. Electrochemical properties are investigated in different media. The values of specific capacitance achieved are 112 F g{sup −1} in 1 M Na{sub 2}SO{sub 4} and 165 F g{sup −1} in 6 M KOH electrolyte, respectively. The assembly of multiple branched MnOOH and graphene flakes results in synergistic effects, forming new electron transfer channels to accelerate electron transfer and provide the pseudocapacitance to increase the overall capacitance. The novel composites have potential applications inmore » the fields of supercapacitors, lithium battery and so on. - Graphical abstract: The MnOOH–graphene nanocomposites shows better specific capacitance with the values achieved 112 F g{sup −1} in 1 M Na{sub 2}SO{sub 4} and 165 F g{sup −1} in 6 M KOH electrolyte, respectively. - Highlights: • Novel MnOOH–graphene nanocomposites were prepared by a one-step hydrothermal method. • The assembly can form new electron transfer channels to accelerate electron transfer. • The capacitive and rate performances are enhanced in both neutral and alkaline medium.« less

Ionic Liquid-Modified Thermosets and Their Nanocomposites: Dispersion, Exfoliation, Degradation, and Cure

NASA Astrophysics Data System (ADS)

Throckmorton, James A.

This dissertation explores the application of a room temperature ionic liquid (RTIL) to problems in the chemistry, processing, and modification of thermosetting polymers. In particular, the solution properties and reaction chemistry of 1-ethyl-3-methyl imidazolium dicyanamide (EMIM-DCN) are applied to problems of nanoparticle dispersion and processing, graphite exfoliation, cyanate ester (CE) cure, and the environmental degradation of CEs. Nanoparticle Dispersion: Nanocomposite processing can be simplified by using the same compound as both a nanoparticle solvent and an initiator for polymerization. This dual-function molecule can be designed both for solvent potential and reaction chemistry. EMIM-DCN, previously shown by our lab to act as an epoxy initiator, is used in the synthesis of silica and acid expanded graphite composites. These composites are then characterized for particle dispersion and physical properties. Individual particle dispersion of silica nanocomposites is shown, and silica nanocomposites at low loading show individual particle dispersion and improved modulus and fracture toughness. GNP nanocomposites show a 70% increase in modulus along with a 10-order of magnitude increase in electrical conductivity at 6.5 vol%, and an electrical percolation threshold of 1.7 vol%. Direct Graphite Exfoliation By Laminar Shear: This work presents a laminar-shear alternative to chemical processing and chaotic flow-fields for the direct exfoliation of graphite and the single-pot preparation of nanocomposites. Additionally, we develop the theory of laminar flow through a 3-roll mill, and apply that theory to the latest developments in the theory of graphite interlayer shear. The resulting nanocomposite shows low electrical percolation (0.5 vol%) and low thickness (1-3 layer) graphite/graphene flakes. Additionally, the effect of processing conditions by rheometry and comparison with solvent-free conditions reveal the interactions between processing and matrix

Facile preparation and characterization of pH sensitive Mt/CMC nanocomposite hydrogel beads for propranolol controlled release.

PubMed

Farhadnejad, Hassan; Mortazavi, Seyed Alireza; Erfan, Mohammad; Darbasizadeh, Behzad; Motasadizadeh, Hamidreza; Fatahi, Yousef

2018-05-01

The main aim of the present study was to design pH-sensitive nanocomposite hydrogel beads, based on carboxymethyl cellulose (CMC) and montmorillonite (Mt)-propranolol (PPN) nanohybrid, and evaluate whether the prepared nanocomposite beads could potentially be used as oral drug delivery systems. PPN-as a model drug-was intercalated into the interlayer space of Mt clay mineral via the ion exchange procedure. The resultant nanohybrid (Mt-PPN) was applied to fabricate nanocomposite hydrogel beads by association with carboxymethyl cellulose. The characterization of test samples was performed using different techniques: X-Ray Diffraction (XRD), IR spectroscopy (FT-IR), thermal gravity analysis (TGA), and scanning electron microscopy (SEM). The drug encapsulation efficiency was evaluated by UV-vis spectroscopy, and was found to be high for Mt/CMC beads. In vitro drug release test was performed in the simulated gastrointestinal conditions to evaluate the efficiency of Mt-PPN/CMC nanocomposite beads as a controlled-release drug carrier. The drug release profiles indicated that the Mt-PPN/CMC nanocomposite beads had high stability against stomach acid and a sustained- and controlled-release profile for PPN under the simulated intestinal conditions. Copyright © 2018 Elsevier B.V. All rights reserved.

Preparation of a Strong Gelatin-Short Linear Glucan Nanocomposite Hydrogel by an in Situ Self-Assembly Process.

PubMed

Ge, Shengju; Li, Man; Ji, Na; Liu, Jing; Mul, Hongyan; Xiong, Liu; Sun, Qingjie

2018-01-10

Gelatin hydrogels exhibit excellent biocompatibility, nonimmunogenicity, and biodegradability, but they have limited applications in the food and medical industries because of their poor mechanical properties. Herein, we first developed an in situ self-assembly process for the preparation of gelatin-short linear glucan (SLG) nanocomposite hydrogels with enhanced mechanical strength. The microstructure, dynamic viscoelasticity, compression behavior, and thermal characteristics of the gelatin-SLG nanocomposite hydrogels were determined using scanning electron microscopy (SEM), dynamic rheological experiments, compression tests, and texture profile analysis tests. The SEM images revealed that nanoparticles were formed by the in situ self-assembly of SLG in the gelatin matrix and that the size of these nanoparticles ranged between 200 and 600 nm. The pores of the nanocomposite hydrogels were smaller than those of the pure gelatin hydrogels. Transmission electron microscopy images and X-ray diffraction further confirmed the presence of SLG nanoparticles with spherical shapes and B-type structures. Compared with pure gelatin hydrogels, the nanocomposite hydrogels exhibited improved mechanical behavior. Notably, the hardness and maximum values of the compressive stress of gelatin-SLG nanocomposites containing 5% SLG increased by about 2-fold and 3-fold, respectively, compared to the corresponding values of pure gelatin hydrogels.

Preparation and characterization of ZnO-TiO{sub 2} nanocomposite for photocatalytic disinfection of bacteria and detoxification of cyanide under visible light

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

Karunakaran, C., E-mail: karunakaranc@rediffmail.com; Abiramasundari, G.; Gomathisankar, P.

2011-10-15

Highlights: {yields} ZnO-TiO{sub 2} nanocomposite, obtained by modified ammonia-evaporation-induced synthetic method, absorbs visible light. {yields} ZnO-TiO{sub 2} nanoparticles catalyze bacteria disinfection and cyanide detoxification under sunlight. {yields} ZnO-TiO{sub 2} nanocomposite is selective in photocatalysis. -- Abstract: ZnO-TiO{sub 2} nanocomposite was prepared by modified ammonia-evaporation-induced synthetic method. It was characterized by powder X-ray diffraction, transmission electron microscopy, selected area electron diffraction, and energy dispersive X-ray, UV-visible diffuse reflectance, photoluminescence and electrochemical impedance spectroscopies. Incorporation of ZnO leads to visible light absorption, larger charge transfer resistance and lower capacitance. The nanocomposite effectively catalyzes the inactivation of E. coli under visible light. Further,more » the prepared nanocomposite displays selective photocatalysis. While its photocatalytic efficiency to detoxify cyanide with visible light is higher than that of TiO{sub 2} P25, its efficiency to degrade methylene blue, sunset yellow and rhodamine B dyes under UV-A light is less than that of TiO{sub 2} P25.« less

Preparation of RHA-silica/graphene oxide nanocomposite for removal of nickel ions from water

NASA Astrophysics Data System (ADS)

Tien, Tran Thi Thuy; Tu, Tran Hoang; Thao, Huynh Nguyen Phuong; Hieu, Nguyen Huu

2017-09-01

In this study, silica was synthesized from rice husk ash (RHA-SiO2) by precipitation method. Graphene oxide (GO) was prepared by modified Hummers method. RHA-SiO2/GO nanocomposite was fabricated by in-situ one-step method using 3-Aminopropyltriethoxysilane (APS) as a coupling agent. The nanocomposite was characterized by using X-ray Fluorescence, X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and Brunauer-Emmett-Teller (BET) specific surface area. The adsorption of RHA-SiO2/GO for Ni2+ ions from water was investigated and compared with the precursors. Ultraviolet-visible (UV-Vis) spectroscopy was used to quantify the amount of the initial and the residual Ni2+ concentration. The maximum adsorption capacity of the nanocomposite for Ni2+ calculated from Langmuir isotherm model, which was 256.4 mg/g. In addition, the adsorption data were well-fitted to the pseudo-second-order kinetic equation. Accordingly, this study demonstrated that RHA-SiO2/GO could be used as a highly efficient adsorbent for removal Ni2+ ions from aqueous solution.

Physicochemical characterization and in vivo evaluation of triamcinolone acetonide-loaded hydroxyapatite nanocomposites for treatment of rheumatoid arthritis.

PubMed

Jafari, Samira; Maleki-Dizaji, Nasrin; Barar, Jaleh; Barzegar-Jalali, Mohammad; Rameshrad, Maryam; Adibkia, Khosro

2016-04-01

The current study was aimed to investigate the anti-inflammatory effect of triamcinolone acetonide-loaded hydroxyapatite (TA-loaded HAp) nanocomposites in the arthritic rat model. The HAp nanocomposites were synthesized through a chemical precipitation method and the drug was subsequently incorporated into the nanocomposites using an impregnation method. The physicochemical properties as well as cytotoxicity of the prepared nanoformulation were examined as well. To evaluate the therapeutic efficacy of the prepared nanoformulation, the various parameters such as paw volume, haematological parameters and histological studies were assessed in the arthritic rats. The nanocomposites with the particle size of 70.45 nm, pore size of 2.71 nm and drug loading of 41.94% were obtained in this study. The specific surface area (aBET) as well as the volume of nitrogen adsorbed on one gram of HAp to complete the monolayer adsorption (Vm) were decreased after the drug loading process. The prepared nanoformulation revealed the slower drug release profile compared to the pure drug. Furthermore, the obtained data from MTT assay showed that the TA-loaded nanocomposites had a lower cytotoxic effect on NIH-3T3 and CAOV-4 cell lines as compared to the pure drug. Furthermore, TA-loaded HAp nanocomposites demonstrated favorable effects on the paw volume as well as the haematological and histopathological abnormalities in the adjuvant-induced arthritic rats. Therefore, TA-loaded HAp nanocomposites are potentially suggested for treatment of rheumatoid arthritis after further required evaluations. Copyright © 2015 Elsevier B.V. All rights reserved.

Preparation and characterization of nanocrystalline cellulose/Eucommia ulmoides gum nanocomposite film.

PubMed

Sun, Qianqian; Zhao, Xinkun; Wang, Dongmei; Dong, Juane; She, Diao; Peng, Pai

2018-02-01

The nanocomposite films were prepared using Eucommia ulmoides gum (EUG) matrix reinforced with nanocrystalline cellulose (NCC) at different concentrations. Subsequently, the obtained films were characterized by Raman spectra, AFM, XRD, TGA, and DSC. Meanwhile, the wettability, mechanical, and water vapor barrier properties of these films were analyzed. AFM noticed that the average sizes of NCC were 81.95×50.17×13.06nm, while the size of molecular chain for EUG was 2530×57.33×1.28nm. In comparison with control film, a certain amount of NCC obviously improved elongation at break and enhanced their crystallinity and ΔH m . More importantly, NCC/EUG nanocomposite films presented lower thermal stability, glass transition temperature (T g ), melting temperature (T m ), and water vapor permeability (WVP) values, especially the WVP values of 4% NCC film were the lowest as 0.28×10 -9 , 0.30×10 -9 , and 0.58×10 -9 g/m/h/Pa at RH 34%, 55%, and 76%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and characteristics of Ag/Pt bimetallic nanocomposites by arc-discharge solution plasma processing.

PubMed

Pootawang, Panuphong; Saito, Nagahiro; Takai, Osamu; Lee, Sang-Yul

2012-10-05

Arc discharge in solution, generated by applying a high voltage of unipolar pulsed dc to electrodes of Ag and Pt, was used as a method to form Ag/Pt bimetallic nanocomposites via electrode erosion by the effects of the electric arc at the cathode (Ag rod) and the sputtering at the anode (Pt rod). Ag/Pt bimetallic nanocomposites were formed as colloidal particles dispersed in solution via the reduction of hydrogen radicals generated during discharge without the addition of chemical precursor or reducing agent. At a discharge time of 30 s, the fine bimetallic nanoparticles with a mean particle size of approximately 5 nm were observed by transmission electron microscopy (TEM). With increasing discharge time, the bimetallic nanoparticle size tended to increase by forming an agglomeration. The presence of the relatively small amount of Pt dispersed in the Ag matrix could be observed by the analytical mapping mode of energy-dispersive x-ray spectroscopy and high-resolution TEM. This demonstrated that the synthesized particle was in the form of a nanocomposite. No contamination of other chemical substances was detected by x-ray photoelectron spectroscopy. Hence, solution plasma could be a clean and simple process to effectively synthesize Ag/Pt bimetallic nanocomposites and it is expected to be widely applicable in the preparation of several types of nanoparticle.

Effect of amphiphilic graft co-polymer-carrier on physical stability of bosentan nanocomposite: Assessment of solubility, dissolution and bioavailability.

PubMed

Kendre, Prakash N; Chaudhari, Pravin D

2018-05-01

Bosentan is a dual endothelin receptor antagonist used in the treatment of pulmonary arterial hypertension (PAH). But the solubility and bioavailability of this drug are poor, which has restricted the design and development of dosage forms for efficient and successful therapy. The present study was carried out to develop nanocomposites using an amphiphilic graft co-polymer (Soluplus®) as a carrier to enhance the solubility and bioavailability of bosentan. The graft co-polymer-based nanocomposite formulation was prepared using the single-emulsion technique. The nanocomposite was characterised in terms of particle size analysis, solubility, percentage entrapment efficiency, drug-loading capacity, surface morphology, drug content, in vitro dissolution, stability and bioavailability. FT-IR study revealed that there was no interaction between the drug and Soluplus®. DSC analysis of the nanocomposite formulation confirmed that the bosentan was completely encapsulated within a Soluplus®. XRD analysis showed that the drug was converted to an amorphous form irreversibly. SEM images showed that the particles were of size 96-129μm and had slightly smooth to rough textured surface. TEM analysis indicated that the diameters of the prepared bosentan nanocomposite after dispersion in distilled water were 13.69-96.78nm. Statistically significant increases in the solubility, dissolution and bioavailability of the drug were observed. It was confirmed that the use of a graft co-polymer carrier-based nanocomposite formulation is a good approach for efficient delivery of bosentan, the solubility and bioavailability being increased manifold. Copyright © 2017 Elsevier B.V. All rights reserved.

Mussel-Inspired Polydopamine Functionalized Plasmonic Nanocomposites for Single-Particle Catalysis.

PubMed

Wang, Jun-Gang; Hua, Xin; Li, Meng; Long, Yi-Tao

2017-01-25

Polydopamine functionalized plasmonic nanocomposites with well-distributed catalytically active small gold nanoislands around large gold core were fabricated without using any chemical reductant or surfactant. The optical properties, surface molecular structures, and ensemble catalytic activity of the gold nanocomposites were investigated by time-of-flight secondary ion mass spectrometry and UV-vis spectroscopy, respectively. Moreover, the considerable catalytic activity of the nanocomposites toward 4-nitrophenol reduction was real time monitored by dark-field spectroscopy techniques at the single-nanoparticle level avoiding averaging effects in bulk systems. According to the obtained plasmonic signals from individual nanocomposites, the electron charging and discharging rates for these nanocomposites during the catalytic process were calculated. Our results offer new insights into the design and synthesis of plasmonic nanocomposites for future catalytic applications as well as a further mechanistic understanding of the electron transfer during the catalytic process at the single-nanoparticle level.

Direct Preparation of Few Layer Graphene Epoxy Nanocomposites from Untreated Flake Graphite.

PubMed

Throckmorton, James; Palmese, Giuseppe

2015-07-15

The natural availability of flake graphite and the exceptional properties of graphene and graphene-polymer composites create a demand for simple, cost-effective, and scalable methods for top-down graphite exfoliation. This work presents a novel method of few layer graphite nanocomposite preparation directly from untreated flake graphite using a room temperature ionic liquid and laminar shear processing regimen. The ionic liquid serves both as a solvent and initiator for epoxy polymerization and is incorporated chemically into the matrix. This nanocomposite shows low electrical percolation (0.005 v/v) and low thickness (1-3 layers) graphite/graphene flakes by TEM. Additionally, the effect of processing conditions by rheometry and comparison with solvent-free conditions reveal the interactions between processing and matrix properties and provide insight into the theory of the chemical and physical exfoliation of graphite crystals and the resulting polymer matrix dispersion. An interaction model that correlates the interlayer shear physics of graphite flakes and processing parameters is proposed and tested.

Preparation and enhanced properties of polyaniline/grafted intercalated ZnAl-LDH nanocomposites

NASA Astrophysics Data System (ADS)

Hu, Jinlong; Gan, Mengyu; Ma, Li; Zhang, Jun; Xie, Shuang; Xu, Fenfang; Shen, JiYue Zheng Xiaoyu; Yin, Hui

2015-02-01

The polymeric nanocomposites (PANI/AD-LDH) were prepared by in situ polymerization based on polyaniline (PANI) and decavanadate-intercalated and γ-aminopropyltriethoxysilane (APTS)-grafted ZnAl-layered double hydroxide (AD-LDH). FTIR and XRD studies confirm the grafting of APTS with decavanadate-intercalated LDH (D-LDH). The extent of grafting (wt%) has also been estimated on the basis of the residue left in nitrogen atmosphere at 800 °C in TGA. SEM and XPS studies show the partial exfoliation of grafted LDH in the PANI matrix and the interfacial interaction between PANI and grafted LDH, respectively. The grafted intercalated layered double hydroxide in reinforcing the properties of the PANI nanocomposites has also been investigated by open circuit potential (OCP), tafel polarization curves (TAF), electrochemical impendence spectroscopy (EIS), salt spray test and TGA-DTA. The experimental results indicate that the PANI/AD-LDH has a higher thermal stability and anticorrosion properties relative to the PANI.

Investigation on the Room-temperature preparation of Cobalt hybrid/Graphene Nanocomposite and application in wastewater purification: Highly Efficient Removal of Congo Red

NASA Astrophysics Data System (ADS)

Wang, L. X.; Zhao, Y. F.; Meng, Q. M.

2018-01-01

Here, we are going to report a simple, low-cost and environmental friendly process to prepare the cobalt hybrid/graphene (Co/G) nanocomposite at room temperature. NaBH4 was used as the reducing agent. Such an approach can be extended to grow some other metal/G nanocomposites, for example, Ni/G, Co/G nanocomposite possesses narrow size-distribution and good dispersion. Because of the special appearance with large surface area, and the special synthesis process of the productions, adsorption experiments for Congo Red were carried out in synthetic wastewater. The CR removal ability of Co/G nanocomposite can reach 263.2 mg/g.

Preparation and characterisation of core-shell CNTs@MIPs nanocomposites and selective removal of estrone from water samples.

PubMed

Gao, Ruixia; Su, Xiaoqian; He, Xiwen; Chen, Langxing; Zhang, Yukui

2011-01-15

This paper reports the preparation of carbon nanotubes (CNTs) functionalized with molecularly imprinted polymers (MIPs) for advanced removal of estrone. CNTs@Est-MIPs nanocomposites with a well-defined core-shell structure were obtained using a semi-covalent imprinting strategy, which employed a thermally reversible covalent bond at the surface of silica-coated CNTs for a large-scale production. The morphology and structure of the products were characterised by transmission electron microscopy and Fourier transform infrared spectroscopy. The adsorption properties were demonstrated by equilibrium rebinding experiments and Scatchard analysis. The results demonstrate that the imprinted nanocomposites possess favourable selectivity, high capacity and fast kinetics for template molecule uptake, yielding an adsorption capacity of 113.5 μmol/g. The synthetic process is quite simple, and the different batches of synthesized CNTs@Est-MIPs nanocomposites showed good reproducibility in template binding. The feasibility of removing estrogenic compounds from environmental water using the CNTs@Est-MIPs nanocomposites was demonstrated using water samples spiked with estrone. Copyright © 2010 Elsevier B.V. All rights reserved.

Intercalated chitosan/hydroxyapatite nanocomposites: Promising materials for bone tissue engineering applications.

PubMed

Nazeer, Muhammad Anwaar; Yilgör, Emel; Yilgör, Iskender

2017-11-01

Preparation and characterization of chitosan/hydroxyapatite (CS/HA) nanocomposites displaying an intercalated structure is reported. Hydroxyapatite was synthesized through sol-gel process. Formic acid was introduced as a new solvent to obtain stable dispersions of nano-sized HA particles in polymer solution. CS/HA dispersions with HA contents of 5, 10 and 20% by weight were prepared. Self-assembling of HA nanoparticles during the drying of the solvent cast films led to the formation of homogeneous CS/HA nanocomposites. Composite films were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-rays (EDX) analysis, Fourier transform infrared (FTIR) spectroscopy, X-rays diffraction (XRD) analysis and thermogravimetric analysis (TGA). SEM and AFM confirmed the presence of uniformly distributed HA nanoparticles on the chitosan matrix surface. XRD patterns and cross-sectional SEM images showed the formation of layered nanocomposites. Complete degradation of chitosan matrix in TGA experiments, led to the formation of nanoporous 3D scaffolds containing hydroxyapatite, β-tricalcium phosphate and calcium pyrophosphate. CS/HA composites can be considered as promising materials for bone tissue engineering applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of magnetic soft phase on the magnetic properties of bulk anisotropic Nd2Fe14B/α-Fe nanocomposite permanent magnets

NASA Astrophysics Data System (ADS)

Li, Yuqing; Yue, Ming; Zhao, Guoping; Zhang, Hongguo

2018-01-01

The effects of soft phase with different particle sizes and distributions on the Nd2Fe14B/α-Fe nanocomposite magnets have been studied by the micro-magnetism simulation. The calculated results show that smaller and/or scattered distribution of soft phase can benefit to the coercivity (H ci) of the nanocomposite magnets. The magnetization moment evolution during magnetic reversal is systematically analyzed. On the other hand, magnetic properties of anisotropic Nd-Fe-B/α-Fe nanocomposite magnets prepared by hot pressing and hot deformation methods also provide evidences for the calculated results.

Preparation and characterization of PANI@G/CWO nanocomposite for enhanced 2-nitrophenol sensing

NASA Astrophysics Data System (ADS)

Khan, Anish; Khan, Aftab Aslam Parwaz; Rahman, Mohammed M.; Asiri, Abdullah M.; Inamuddin; Alamry, Khalid A.; Hameed, Salem A.

2018-03-01

A new material by polymer insertion via graphene oxide into cerium tungstate was prepared by very simple oxidation-reduction method. Aniline polymerization was done on the surface of graphene oxide (GO) which was reduced to graphene (G) simultaneously mixed with separately prepared inorganic matrices of cerium tungstate (Ce2(WO4)3 (CWO)). PANI@G/CWO was characterized by various spectroscopic methods as SEM, FTIR, TGA, XRD and XPS to confirm its possibilities. Selective 2-nitrophenol sensor was fabricated on flat glassy carbon electrode (GCE) and PANI@G/CWO nanocomposites in the form of thin layer. It was found excellent sensitivity as well as long life spam with broad dynamic concentration range (LDR) that showed efficient electrochemical performance towards 2-nitrophenol on fabricated chemical sensor by PANI@G/CWO. The linear calibration curve (r2 = 0.9914) with wide range of 2-nitrophenol concentration (1.0 nM-1.0 mM) was found having the detection limit of 0.87 nM while the sensitivity of the sensor was around 1.229 μ A μM-1 cm-2. It was introduced a new route for the development of a versatile phenolic sensor based on PANI@G/CWO nanocomposites by I-V method that is proved more selective and sensitive for environmental toxic materials.

Characterisations of collagen-silver-hydroxyapatite nanocomposites

NASA Astrophysics Data System (ADS)

Ciobanu, C. S.; Popa, C. L.; Petre, C. C.; Jiga, G.; Trusca, R.; Predoi, D.

2016-05-01

The XRD analysis were performed to confirm the formation of hydroxyapatite structure in collagen-silver-hydroxyapatite nanocomposites. The molecular interaction in collagen-hydroxyapatite nanocomposites was highlighted by Fourier transform infrared spectroscopy (FTIR) analysis. The SEM showed a nanostructure of collagen-silverhydroxyapatite nanocomposites composed of nano needle-like particles in a veil with collagen texture. The presence of vibrational groups characteristics to the hydroxyapatite structure in collagen-silver-hydroxyapatite (AgHApColl) nanocomposites was investigated by FTIR.

One-pot preparation of unsaturated polyester nanocomposites containing functionalized graphene sheets via a novel solvent-exchange method

USDA-ARS?s Scientific Manuscript database

This paper reports a convenient one-pot method integrating a novel solvent-exchange method into in situ melt polycondensation to fabricate unsaturated polyester nanocomposites containing functionalized graphene sheets (FGS). A novel solvent-exchange method was first developed to prepare graphene oxi...

Fe2O3 hollow sphere nanocomposites for supercapacitor applications

NASA Astrophysics Data System (ADS)

Zhao, Yu; Wen, Yang; Xu, Bing; Lu, Lu; Ren, Reiming

2018-02-01

Nanomaterials have attracted increasing interest in electrochemical energy storage and conversion. Hollow sphere Fe2O3 nanocomposites were successfully prepared through facile low temperature water-bath method with carbon sphere as hard template. The morphology and microstructure of samples were characterized by X-ray diffraction (XRD) and Scanning electron microscope (SEM), respectively. Through hydrolysis mechanism, using ferric chloride direct hydrolysis, iron hydroxide coated on the surface of carbon sphere, after high temperature calcination can form the hollow spherical iron oxide materials. Electrochemical performances of the hollow sphere Fe2O3 nanocomposites electrodes were investigated by cyclic voltammery (CV) and galvanostatic charge/discharge. The Pure hollow sphere Fe2O3 nanocomposites achieves a specific capacitance of 125 F g-1 at the current density of 85 mA g-1. The results indicate that the uniform dispersion of hollow ball structure can effectively reduce the particle reunion in the process of charging and discharging.

Synthesis and characterization of polyaniline coated gold nanocomposites

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

Zuber, Siti Nurzulaiha Mohd; Kamarun, Dzaraini; Zaki, Hamizah

2015-08-28

Considerable attention has been drawn during the last two decades to prepare nanocomposites consists of conducting polymer and noble metal due to their potential ability to generate a new class of material with novel optical, chemical, electronic or mechanical properties for various applications. In this work, an attempt has been made to synthesize nanocomposite of polyaniline (PANI) coated with gold nanoparticles (AuNPs) chemically with various types of surfactants such as polyvinylpyrrolidone (PVP), and sodium dodecyl sulphate (SDS) which act as stabilizing agents to help in stabilization of the PANI/Gold nanocomposites system. The synthesized nanocomposites were characterized by UV-Visible, field emissionmore » scanning electron microscope (FESEM) and particle size analyzer (PSA). The formation of finger like structure can be seen in the FESEM images when the AuNPs were incorporated into the polymer matrix. The EDX data showed that 18.66% and 12.67% of AuNPs atoms were present in the composite system thus proved the incorporation of AuNPs into the polymer matrix. A small red shift of the absorption peak in the UV-Vis of both PANI/AuNPs composites system may be due to the incorporation of AuNPs in the PANI matrix.« less

Anisotropic elasticity of quasi-one-component polymer nanocomposites.

PubMed

Voudouris, Panayiotis; Choi, Jihoon; Gomopoulos, Nikos; Sainidou, Rebecca; Dong, Hongchen; Matyjaszewski, Krzysztof; Bockstaller, Michael R; Fytas, George

2011-07-26

The in-plane and out-of-plane elastic properties of thin films of "quasi-one-component" particle-brush-based nanocomposites are compared to those of "classical" binary particle-polymer nanocomposite systems with near identical overall composition using Brillouin light scattering. Whereas phonon propagation is found to be independent of the propagation direction for the binary particle/polymer blend systems, a pronounced splitting of the phonon propagation velocity along the in-plane and out-of-plane film direction is observed for particle-brush systems. The anisotropic elastic properties of quasi-one-component particle-brush systems are interpreted as a consequence of substrate-induced order formation into layer-type structures and the associated breaking of the symmetry of the film. The results highlight new opportunities to engineer quasi-one-component nanocomposites with advanced control of structural and physical property characteristics based on the assembly of particle-brush materials.

Sustained release of doxorubicin from zeolite-magnetite nanocomposites prepared by mechanical activation.

PubMed

Arruebo, Manuel; Fernández-Pacheco, Rodrigo; Irusta, Silvia; Arbiol, Jordi; Ibarra, M Ricardo; Santamaría, Jesús

2006-08-28

Nanocomposites consisting of magnetite and FAU zeolite with a high surface area and adsorption capacity have been prepared by mechanical activation using high-energy milling at room temperature. FTIR results, as well as HRTEM, EFTEM, and XPS measurements, show that the resulting magnetic nanoparticles are covered by a thin aluminosilicate coating. A saturation magnetization as high as 16 emu g(-1) and 94.2 Oe of coercivity were observed for the obtained composites. The main advantages of this synthesis procedure are (i) simplicity of the preparation procedure, (ii) prevention of agglomeration of the magnetite nanoparticles to a large extent, and (iii) absence of free magnetite outside the zeolitic matrix. In addition, in vitro experiments revealed that the nanoparticles prepared were able to store and release substantial amounts of doxorubicin. In view of these advantages, these magnetic nanoparticles can be considered as potential candidates for drug-delivery applications.

Sustained release of doxorubicin from zeolite magnetite nanocomposites prepared by mechanical activation

NASA Astrophysics Data System (ADS)

Arruebo, Manuel; Fernández-Pacheco, Rodrigo; Irusta, Silvia; Arbiol, Jordi; Ibarra, M. Ricardo; Santamaría, Jesús

2006-08-01

Nanocomposites consisting of magnetite and FAU zeolite with a high surface area and adsorption capacity have been prepared by mechanical activation using high-energy milling at room temperature. FTIR results, as well as HRTEM, EFTEM, and XPS measurements, show that the resulting magnetic nanoparticles are covered by a thin aluminosilicate coating. A saturation magnetization as high as 16 emu g-1 and 94.2 Oe of coercivity were observed for the obtained composites. The main advantages of this synthesis procedure are (i) simplicity of the preparation procedure, (ii) prevention of agglomeration of the magnetite nanoparticles to a large extent, and (iii) absence of free magnetite outside the zeolitic matrix. In addition, in vitro experiments revealed that the nanoparticles prepared were able to store and release substantial amounts of doxorubicin. In view of these advantages, these magnetic nanoparticles can be considered as potential candidates for drug-delivery applications.

Preparation and characterization of porous reduced graphene oxide based inverse spinel nickel ferrite nanocomposite for adsorption removal of radionuclides.

PubMed

Lingamdinne, Lakshmi Prasanna; Choi, Yu-Lim; Kim, Im-Soon; Yang, Jae-Kyu; Koduru, Janardhan Reddy; Chang, Yoon-Young

2017-03-15

For the removal of uranium(VI) (U(VI)) and thorium(IV) (Th(IV)), graphene oxide based inverse spinel nickel ferrite (GONF) nanocomposite and reduced graphene oxide based inverse spinel nickel ferrite (rGONF) nanocomposite were prepared by co-precipitation of GO with nickel and iron salts in one pot. The spectral characterization analyses revealed that GONF and rGONF have a porous surface morphology with an average particle size of 41.41nm and 32.16nm, respectively. The magnetic property measurement system (MPMS) studies confirmed the formation of ferromagnetic GONF and superparamagnetic rGONF. The adsorption kinetics studies found that the pseudo-second-order kinetics was well tune to the U(VI) and Th(IV) adsorption. The results of adsorption isotherms showed that the adsorption of U(VI) and Th(IV) were due to the monolayer on homogeneous surface of the GONF and rGONF. The adsorptions of both U(VI) and Th(IV) were increased with increasing system temperature from 293 to 333±2K. The thermodynamic studies reveal that the U(VI) and Th(IV) adsorption onto GONF and rGONF was endothermic. GONF and rGONF, which could be separated by external magnetic field, were recycled and re-used for up to five cycles without any significant loss of adsorption capacity. Copyright © 2016 Elsevier B.V. All rights reserved.

Γ-Al₂O₃-based nanocomposite adsorbents for arsenic(V) removal: assessing performance, toxicity and particle leakage.

PubMed

Onnby, Linda; Svensson, Christian; Mbundi, Lubinda; Busquets, Rosa; Cundy, Andrew; Kirsebom, Harald

2014-03-01

The generation and development of effective adsorption materials for arsenic removal are urgently needed due to acute arsenic contamination of water sources in many regions around the world. In the search for these new adsorbents, the application of nanomaterials or nanocomposites, and especially the use of nanoparticles (NPs), has proven increasingly attractive. While the adsorptive performance of a range of nanocomposite and nanomaterial-based systems has been extensively reviewed in previously-published literature, the stability of these systems in terms of NP release, i.e. the ability of the nanomaterial or nanocomposite to retain incorporated NPs, is less well understood. Here we examine the performance of nanocomposites comprised of aluminium oxide nanoparticles (AluNPs) incorporated in macroporous polyacrylamide-based cryogels (n-Alu-cryo, where n indicates the percentage of AluNPs in the polymer material (n=0-6%, w/v)) for As(V) adsorption, and evaluate AluNP leakage before and after the use of these materials. A range of techniques is utilised and assessed (SEM, TEM, mass weight change, PIXE and in vitro toxicity studies). The 4-Alu-cryo nanocomposite was shown to be optimal for minimising AluNP losses while maximising As(V) removal. From the same nanocomposite we were further able to show that NP losses were not detectable at the AluNP concentrations used in the study. Toxicity tests revealed that no cytotoxic effects could be observed. The cryogel-AluNPs composites were not only effective in As(V) removal but also in immobilising the AluNPs. More challenging flow-through conditions for the evaluation of NP leakage could be included as a next step in a continued study assessing particle loss and subsequent toxicity. Copyright © 2013 Elsevier B.V. All rights reserved.

Preparation of PEO/Clay Nanocomposites Using Organoclay Produced via Micellar Adsorption of CTAB

PubMed Central

Gürses, Ahmet; Ejder-Korucu, Mehtap; Doğar, Çetin

2012-01-01

The aim of this study was the preparation of polyethylene oxide (PEO)/clay nanocomposites using organoclay produced via micellar adsorption of cethyltrimethyl ammonium bromide (CTAB) and their characterisation by X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectra, and the investigation of certain mechanical properties of the composites. The results show that the basal distance between the layers increased with the increasing CTAB/clay ratio as parallel with the zeta potential values of particles. By considering the aggregation number of CTAB micelles and interlayer distances of organo-clay, it could be suggested that the predominant micelle geometry at lower CTAB/clay ratios is an ellipsoidal oblate, whereas, at higher CTAB/clay ratios, sphere-ellipsoid transition occurs. The increasing tendency of the exfoliation degree with an increase in clay content may be attributed to easier diffusion of PEO chains to interlayer regions. FT-IR spectra show that the intensity of Si-O stretching vibrations of the organoclays (1050 cm−1) increased, especially in the ratios of 1.0 g/g clay and 1.5 g/g clay with the increasing CTAB content. It was observed that the mechanical properties of the composites are dependent on both the CTAB/clay ratios and clay content of the composites. PMID:23365515

Graphene-sulfur nanocomposites for rechargeable lithium-sulfur battery electrodes

DOEpatents

Liu, Jun; Lemmon, John P; Yang, Zhenguo; Cao, Yuiliang; Li, Xiaolin

2014-06-17

Rechargeable lithium-sulfur batteries having a cathode that includes a graphene-sulfur nanocomposite can exhibit improved characteristics. The graphene-sulfur nanocomposite can be characterized by graphene sheets with particles of sulfur adsorbed to the graphene sheets. The sulfur particles have an average diameter less than 50 nm..

Hollow Fe₃O₄/Graphene Oxide Nanocomposites as Novel Rapamycin Carrier: Formulation Optimization and In Vitro Characterization.

PubMed

Cao, Liangli; Jiang, Yuren; Chen, Zhencheng

2018-05-01

In the present research an attempt was made to develop and optimize rapamycin (Rapa) loaded hollow magnetic Fe3O4/graphene oxide (Fe3O4/GO) nanocomposites using solvent evaporation technique and response surface methodology (RSM). A Box-Behnken design (BBD) with a three-level, three-factor was used to determine preparation parameters that would achieve the highest encapsulation efficiency (EE) and drug loading capacity (DLC). At optimum conditions such as mass ratio of Rapa to Fe3O4/GO (Rapa: Fe3O4/GO) 0.45, oscillation rate 144.0, and volume ratio of water to solvent (W/S) 4.2, the EE and DLC of experimentally prepared particles reached 84.92 ± 5.50% and 28.68 ± 2.54% respectively. The morphological assessment results showed that hollow Fe3O4 nano-aggregates were evenly and tightly dispersed on the layer of GO membrane. After the addition of GO and encapsulation of Rapa, the Fe3O4/GO nanocomposites and Rapa loaded magnetic Fe3O4/GO (Fe3O4/GO-Rapa) nanocomposites showed saturation magnetization of 57.77 and 40.71 emu/g respectively. The drug releasing experiment indicated a slightly acidic atmosphere, which was suitable for Rapa releasing from the obtained Fe3O4/GO nanocomposites. The cell counting Kit-8 (CCK-8) assays demonstrated the hollow Fe3O4/GO nanocomposites could effectively improve the efficacy of Rapa in killing HepG2 cells, which displayed a concentration-dependent manner. All these results suggested the prepared Fe3O4/GO nanocomposites have a potential application in drug delivery system.

Nanocomposites

DTIC Science & Technology

2013-09-10

reduced density larger than unity indicates densification of polymer nanocomposites. Fullerene (C60) has a 0.76 nm diameter, which is hypothesized to be...found a definite particle size dependent density and tensile modulus. The effect is subtle, yet, quite robust as various systems, inorganic or

Polysaccharide-based nanocomposites and their applications

PubMed Central

Zheng, Yingying; Monty, Jonathan; Linhardt, Robert J.

2014-01-01

Polysaccharide nanocomposites have become increasingly important materials over the past decade. Polysaccharides offer a green alternative to synthetic polymers in the preparation of soft nanomaterials. They have also been used in composites with hard nanomaterials, such as metal nanoparticles and carbon-based nanomaterials. This mini review describes methods for polysaccharide nanocomposite preparation and reviews the various types and diverse applications for these novel materials. PMID:25498200

PREPARATION OF SPHERICAL URANIUM DIOXIDE PARTICLES

DOEpatents

Levey, R.P. Jr.; Smith, A.E.

1963-04-30

This patent relates to the preparation of high-density, spherical UO/sub 2/ particles 80 to 150 microns in diameter. Sinterable UO/sub 2/ powder is wetted with 3 to 5 weight per cent water and tumbled for at least 48 hours. The resulting spherical particles are then sintered. The sintered particles are useful in dispersion-type fuel elements for nuclear reactors. (AEC)

Process for preparation of large-particle-size monodisperse latexes

NASA Technical Reports Server (NTRS)

Vanderhoff, J. W.; Micale, F. J.; El-Aasser, M. S.; Kornfeld, D. M. (Inventor)

1981-01-01

Monodisperse latexes having a particle size in the range of 2 to 40 microns are prepared by seeded emulsion polymerization in microgravity. A reaction mixture containing smaller monodisperse latex seed particles, predetermined amounts of monomer, emulsifier, initiator, inhibitor and water is placed in a microgravity environment, and polymerization is initiated by heating. The reaction is allowed to continue until the seed particles grow to a predetermined size, and the resulting enlarged particles are then recovered. A plurality of particle-growing steps can be used to reach larger sizes within the stated range, with enlarge particles from the previous steps being used as seed particles for the succeeding steps. Microgravity enables preparation of particles in the stated size range by avoiding gravity related problems of creaming and settling, and flocculation induced by mechanical shear that have precluded their preparation in a normal gravity environment.

Impedance analysis on PVA/PVP: GO blend nanocomposite polymer films

NASA Astrophysics Data System (ADS)

Rao, M. C.; Basha, S. K. Shahenoor; Kumar, B. Ranjit

2018-05-01

Nanocomposite polymer films have been prepared by doping Graphene oxide (GO) in PVA/PVP blend polymers by solution cast technique. AC conductivity studies were performed on to the prepared nanocomposite films and the maximum ionic conductivity is found to be 6.13x10-4 Scm-1 for (0.30:0.3) wt% of nanocomposite polymer film at room temperature. The maximum ionic conductivity of nanocomposite polymer films of PVA/PVP: GO holds great promise in potential applications.

Preparation and characterization of photoactive composite kaolinite/TiO(2).

PubMed

Mamulová Kutláková, K; Tokarský, J; Kovář, P; Vojtěšková, S; Kovářová, A; Smetana, B; Kukutschová, J; Čapková, P; Matějka, V

2011-04-15

Preparation of nanocomposite kaolinite/TiO(2), using hydrolysis of titanyl sulfate in the presence of kaolin was addressed. A variable (kaolin)/(titanyl sulfate) ratio has been used in order to achieve the desired TiO(2) content in prepared nanocomposites. Calcination of the composites at 600 °C led to the transformation of the kaolinite to metakaolinite and to origination of metakaolinite/TiO(2) composites. The prepared samples were investigated using X-ray fluorescence spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetry and diffuse reflectance spectroscopy in the UV-VIS region. Structural ordering of TiO(2) on the kaolinite particle surface was modeled using empirical force field atomistic simulations in the Material Studio modeling environment. Photodegradation activity of the composites prepared was evaluated by the discoloration of Acid Orange 7 aqueous solution. Copyright © 2011 Elsevier B.V. All rights reserved.

Preparation, characterization, dielectric properties and diffusion studies of styrene butadiene rubber (SBR)/manganous tungstate (MnWO4) nanocomposites

NASA Astrophysics Data System (ADS)

Jasna, V. C.; Ramesan, M. T.

2017-06-01

Nanocomposites based on SBR with different content of manganous tungstate nanoparticles were prepared and characterized by FTIR, UV-visible spectroscopy, XRD, SEM, TGA, DSC and impedance analysis. The interaction between nanoparticles and the elastomer was clear from the shift in peaks of UV and FTIR. XRD and SEM analysis showed the uniform arrangement of nanoparticles in SBR matrix. Glass transition temperature, thermal stability and dielectric properties of composites were enhanced by the addition of nanoparticles. Sorption studies of nanocomposites were done in aromatic solvents at different temperature. Sorption data obtained were used to estimate the thermodynamic properties.

Room temperature synthesis and optical studies on Ag and Au mixed nanocomposite polyvinylpyrrolidone polymer films.

PubMed

Udayabhaskar, R; Mangalaraja, R V; Manikandan, D; Arjunan, V; Karthikeyan, B

2012-12-01

Optical properties of silver, gold and bimetallic (Au:Ag) nanocomposite polymer films which are prepared by chemical method have been reported. The experimental data was correlated with the theoretical calculations using Mie theory. We adopt small change in the theoretical calculations of bimetallic/mixed particle nanocomposite and the theory agrees well with the experimental data. Polyvinylpyrrolidone (PVP) was used as reducing and capping agent. Fourier transform infrared spectroscopy (FTIR) study reveals the presence of different functional groups, the possible mechanism that leads to the formation of nanoparticles by using PVP alone as reducing agent. Optical absorption spectra of Ag and Au nanocomposite polymers show a surface plasmon resonance (SPR) band around 430 and 532 nm, respectively. Thermal annealing effect on the prepared samples at 60 °C for different time durations result in shift of SPR band maximum and varies the full width at half maximum (FWHM). Absorption spectra of Au:Ag bimetallic films show bands at 412 and 547 nm confirms the presence of Ag and Au nanoparticles in the composite. Copyright © 2012 Elsevier B.V. All rights reserved.

Thermal and mechanical properties of palm oil-based polyurethane acrylate/clay nanocomposites prepared by in-situ intercalative method and electron beam radiation

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

Salih, A. M.; Ahmad, Mansor Bin; Ibrahim, Nor Azowa

2014-02-12

Palm oil based-polyurethane acrylate (POBUA)/clay nanocomposites were prepared via in-situ intercalative polymerization using epoxidized palm oil acrylate (EPOLA) and 4,4' methylene diphenyl diisocyante (MDI). Organically modified Montmorillonite (ODA-MMT) was incorporated in EPOLA (1, 3 and 5%wt), and then subjected to polycondensation reaction with MDI. Nanocomposites solid films were obtained successfully by electron beam radiation induced free radical polymerization (curing). FTIR results reveal that the prepolymer was obtained successfully, with nanoclay dispersed in the matrix. The intercalation of the clay in the polymer matrix was investigated by XRD and the interlayer spacing of clay was found to be increased up tomore » 37 Å, while the structure morphology of the nanocomposites was investigated by TEM and SEM. The nanocomposites were found to be a mixture of exfoliated and intercalated morphologies. The thermal stability of the nanocomposites was significantly increased by incorporation of nanoclay into the polymer matrix. DSC results reveal that the Tg was shifted to higher values, gradually with increasing the amount of filler in the nanocomposites. Tensile strength and Young's modulus of the nanocomposites showed remarkable improvement compared to the neat POBUA.« less

Hydrogen storage and hydrolysis properties of core-shell structured Mg-MFx (M=V, Ni, La and Ce) nano-composites prepared by arc plasma method

NASA Astrophysics Data System (ADS)

Mao, Jianfeng; Zou, Jianxin; Lu, Chong; Zeng, Xiaoqin; Ding, Wenjiang

2017-10-01

In this work, core-shell structured Mg-MFx (M = V, Ni, La and Ce) nano-composites are prepared by using arc plasma method. The particle size distribution, phase components, microstructures, hydrogen sorption properties of these composites and hydrolysis properties of their corresponding hydrogenated powders are carefully investigated. It is shown that the addition of MFx through arc plasma method can improve both the hydrogen absorption kinetics of Mg and the hydrolysis properties of corresponding hydrogenated powders. Among them, the Mg-NiF2 composite shows the best hydrogen absorption properties at relatively low temperatures, which can absorb 3.26 wt% of H2 at 373 K in 2 h. Such rapid hydrogen absorption rate is mainly due to the formation of Mg2Ni and MgF2 on Mg particles during arc evaporation and condensation. In contrast, measurements also show that the hydrogenated Mg-VF3 composite has the lowest peak desorption temperature and the fastest hydrolysis rate among all the hydrogenated Mg-MFx composites. The less agglomeration tendency of Mg particles and VO2 covered on MgH2 particles account for the reduced hydrogen desorption temperature and enhanced hydrolysis rate.

Green chemistry approach for the synthesis of ZnO-carbon dots nanocomposites with good photocatalytic properties under visible light.

PubMed

Bozetine, Hakima; Wang, Qi; Barras, Alexandre; Li, Musen; Hadjersi, Toufik; Szunerits, Sabine; Boukherroub, Rabah

2016-03-01

We report on a simple and one-pot synthetic method to produce ZnO/carbon quantum dots (ZnO/CQDs) nanocomposites. The morphological features and chemical composition of the nanocomposites were characterized using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analyses (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optical properties of the nanocomposites were examined using UV-visible (UV-vis) spectrophotometry. The photocatalytic activity of the ZnO/CQDs was evaluated for the degradation of a model organic pollutant, rhodamine B, under visible light irradiation at room temperature. The highly efficient photodegradation capability of the nanocomposite was demonstrated by comparison with ZnO particles, prepared using identical experimental conditions. Overall, the present approach adheres to green chemistry principles and the nanocomposite holds promise for the development of remarkably efficient catalytic systems. Copyright © 2015 Elsevier Inc. All rights reserved.

Preparation and Application of LDPE/ZnO Nanocomposites for Extending Shelf Life of Fresh Strawberries

PubMed Central

Mohammadizadeh, Mehri

2015-01-01

Summary Strawberries have a very short post-harvest life mostly due to their relatively high water content, intense metabolic activity and susceptibility to microbial rot. Antimicrobial low-density polyethylene nanocomposite films containing ZnO nanoparticles at different mass fractions were prepared by melt mixing and followed by compression moulding using a hot press machine. Fresh strawberries were packed in nanocomposite films and stored at 4 °C. Their microbial stability, ascorbic acid content and titratable acidity were evaluated after 0, 4, 8, 12 and 16 days of storage. Microbial growth rate was significantly reduced up to 16 days as a result of the use of nanocomposite packaging material containing ZnO nanoparticles. By increasing the ZnO nanoparticle mass fraction to 5%, the antimicrobial activity of the film increased. All packages containing the ZnO nanoparticles kept the microbial load of fresh strawberries below the level that affects shelf life (5 log CFU/g) up to 16 days. The lowest degradation of ascorbic acid content (6.55 mg per 100 g), and loss of acidity (0.68%) were observed in packages containing 3% of ZnO nanoparticles with 10% polyethylene-grafted maleic anhydride. PMID:27904384

Preparation and Application of LDPE/ZnO Nanocomposites for Extending Shelf Life of Fresh Strawberries.

PubMed

Emamifar, Aryou; Mohammadizadeh, Mehri

2015-12-01

Strawberries have a very short post-harvest life mostly due to their relatively high water content, intense metabolic activity and susceptibility to microbial rot. Antimicrobial low-density polyethylene nanocomposite films containing ZnO nanoparticles at different mass fractions were prepared by melt mixing and followed by compression moulding using a hot press machine. Fresh strawberries were packed in nanocomposite films and stored at 4 °C. Their microbial stability, ascorbic acid content and titratable acidity were evaluated after 0, 4, 8, 12 and 16 days of storage. Microbial growth rate was significantly reduced up to 16 days as a result of the use of nanocomposite packaging material containing ZnO nanoparticles. By increasing the ZnO nanoparticle mass fraction to 5%, the antimicrobial activity of the film increased. All packages containing the ZnO nanoparticles kept the microbial load of fresh strawberries below the level that affects shelf life (5 log CFU/g) up to 16 days. The lowest degradation of ascorbic acid content (6.55 mg per 100 g), and loss of acidity (0.68%) were observed in packages containing 3% of ZnO nanoparticles with 10% polyethylene-grafted maleic anhydride.

Effects of swift heavy ion irradiation on structural, optical and photocatalytic properties of ZnO–CuO nanocomposites prepared by carbothermal evaporation method

PubMed Central

Kuriakose, Sini; Avasthi, D K

2015-01-01

Summary ZnO–CuO nanocomposite thin films were prepared by carbothermal evaporation of ZnO and Cu, combined with annealing. The effects of 90 MeV Ni7+ ion irradiation on the structural and optical properties of ZnO–CuO nanocomposites were studied by using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV–visible absorption spectroscopy and Raman spectroscopy. XRD studies showed the presence of ZnO and CuO nanostructures in the nanocomposites. FESEM images revealed the presence of nanosheets and nanorods in the nanocomposites. The photocatalytic activity of ZnO–CuO nanocomposites was evaluated on the basis of degradation of methylene blue (MB) and methyl orange (MO) dyes under sun light irradiation and it was observed that swift heavy ion irradiation results in significant enhancement in the photocatalytic efficiency of ZnO–CuO nanocomposites towards degradation of MB and MO dyes. The possible mechanism for the enhanced photocatalytic activity of ZnO–CuO nanocomposites is proposed. We attribute the observed enhanced photocatalytic activity of ZnO–CuO nanocomposites to the combined effects of improved sun light utilization and suppression of the recombination of photogenerated charge carriers in ZnO–CuO nanocomposites. PMID:25977864

Nanocomposites of zeolite-titanium(IV) oxides: Preparation, characterization, adsorption, photocatalytic and bactericidal properties

NASA Astrophysics Data System (ADS)

Domoroshchina, Elena; Kravchenko, Galina; Kuz'micheva, Galina

2017-06-01

NT/zeolite nanocomposites (NT - nanosized titanium(IV) oxides: η-phase and Hombifine N with anatase; zeolite: Beta(25), ZSM-5 with different modules Si/Al, MOR, or Y) have been obtained by two methods: modified cold-impregnation method (method 1) and in situ method of introduction of zeolites into the reaction mixture during the synthesis of NT by hydrolysis of TiOSO4×xH2SO4×yH2O or TiOSO4×2H2O aqueous solutions (method 2), performed for the first time. According to the X-ray data, the following differences in the NT:zeolite systems under investigation have been revealed: the mixture of zeolites and NT in nanocrystalline (Hombifine N/zeolite) or amorphous states (η-phase/zeolite, except for η-phase/MOR, where NT peaks are absent) (method 1), and the mixture of Y-zeolite and amorphous NT or only Y-zeolite without NT (method 2), which indicates the different levels of interaction between NT and zeolites in the systems studied. The best characteristics of properties (photocatalytic, adsorption, and antibacterial) have been revealed in the nanocomposites synthesized by the method 2. The correlation between the photoreaction rate constant (the k value) under UV irradiation in the presence of nanocomposites (kmax for NT/ZSM-5(12)) and the type of precursor, its pH, synthesis duration, NT:zeolite ratio, organic dye composition (methyl orange or Rhodamine G) has been established. The highest degree of extraction of P(V) ions from model aqueous systems has been observed in the presence of nanocomposites with the largest total surface area of all particles (Rmax = 99.48% for NT/MOR). The correlation between the sorption degree of P(V) ions and the modulus of zeolite is possible. Antibacterial activity in the dark towards Escherichia coli has been found for Y and Beta(25) zeolites and nanocomposites on their basis (methods 1 and 2) with the maximum diameter of bacterial growth inhibition (18 mm) obtained for NT/Beta(25) (method 2) synthesized only from TiOSO4×xH2SO4�

Polymer nanocomposite dielectric and electrical properties with quantum dots nanofiller

NASA Astrophysics Data System (ADS)

Ahmed, R. M.; Morsi, R. M. M.

2017-10-01

Nanocomposite films of different contents of CdSe/ZnS quantum dots nanoparticles embedded in hosting matrix of polyvinyl chloride (PVC) were prepared by simple solution casting method. Electrical and dielectric properties of nanocomposites films were investigated in the temperature range 323-393 (K) and at frequencies (50-2000) kHz. The frequency dependence of AC conductivity was following the universal power law. The values of the frequency exponent, s, revealed that the conduction mechanism at low temperature is considered by small polaron tunneling model, whereas at high temperature, it is related to CBH model. The activation energy values (ΔE) were depending on nanoparticle concentration as well as frequency. Also, X-ray diffraction (XRD) enabled approximately estimating the average particle size of the nanoparticles incorporated in PVC.

Organic/Inorganic Hybrid Polymer/Clay Nanocomposites

NASA Technical Reports Server (NTRS)

Park, Cheol; Connell, John W.; Smith, Joseph G., Jr.

2003-01-01

A novel class of polymer/clay nanocomposites has been invented in an attempt to develop transparent, lightweight, durable materials for a variety of aerospace applications. As their name suggests, polymer/ clay nanocomposites comprise organic/ inorganic hybrid polymer matrices containing platelet-shaped clay particles that have sizes of the order of a few nanometers thick and several hundred nanometers long. Partly because of their high aspect ratios and high surface areas, the clay particles, if properly dispersed in the polymer matrix at a loading level of 1 to 5 weight percent, impart unique combinations of physical and chemical properties that make these nanocomposites attractive for making films and coatings for a variety of industrial applications. Relative to the unmodified polymer, the polymer/ clay nanocomposites may exhibit improvements in strength, modulus, and toughness; tear, radiation, and fire resistance; and lower thermal expansion and permeability to gases while retaining a high degree of optical transparency.

Green Synthesis of Oxovanadium(IV)/chitosan Nanocomposites and Its Ameliorative Effect on Hyperglycemia, Insulin Resistance, and Oxidative Stress.

PubMed

Liu, Yanjun; Jie, Xu; Guo, Yongli; Zhang, Xin; Wang, Jingfeng; Xue, Changhu

2016-02-01

In this paper, the preparation, characterization, and ameliorative effect on high-fat high-sucrose diet-induced hyperglycemia, insulin resistance, oxidative stress in mice of novel oxovanadium(IV)/chitosan (OV/CS) nanocomposites were investigated. The nanobiocomposite was produced by chemical reduction by chitosan and L-ascorbic acid using microwave heating, under environment-friendly conditions, using aqueous solutions, and notably, by using both mediators as reducing and stabilizing agents. In addition, OV/CS nanocomposites were characterized by transmission electron microscopy, energy dispersive spectroscopy, particle size, and zeta potential measurements. In vivo experiments were designed to examine whether the OV/CS nanocomposites would provide additional benefits on oxidative stress, hyperglycemia, and insulin resistance in mice with type 2 diabetes. The results rendered insulin resistant by treating with OV/CS nanocomposites alleviate insulin resistance and improve oxidative stress. Such nanocomposite seem to be a valuable therapy to achieve and/or maintain glycemic control and therapeutic agents in the treatment arsenal for insulin resistance and type 2 diabetes.

Green Preparation of Epoxy/Graphene Oxide Nanocomposites Using a Glycidylamine Epoxy Resin as the Surface Modifier and Phase Transfer Agent of Graphene Oxide.

PubMed

Tang, Xinlei; Zhou, Yang; Peng, Mao

2016-01-27

In studies of epoxy/graphene oxide (GO) nanocomposites, organic solvents are commonly used to disperse GO, and vigorous mechanical processes and complicated modification of GO are usually required, increasing the cost and hindering the development and application of epoxy nanocomposites. Here, we report a green, facile, and efficient method of preparing epoxy/GO nanocomposites. When triglycidyl para-aminophenol (TGPAP), a commercially available glycidyl amine epoxy resin with one tertiary amine group per molecule, is used as both the surface modifier and phase transfer agent of GO, GO can be directly and rapidly transferred from water to diglycidyl ether of bisphenol A and other types of epoxy resins by manual stirring under ambient conditions, whereas GO cannot be transferred to these epoxy resins in the absence of TGPAP. The interaction between TGPAP and GO and the effect of the TGPAP content on the dispersion of GO in the epoxy matrix were investigated systematically. Superior dispersion and exfoliation of GO nanosheets and remarkably improved mechanical properties, including tensile and flexural properties, toughness, storage modulus, and microhardness, of the epoxy/GO nanocomposites with a suitable amount of TGPAP were demonstrated. This method is organic-solvent-free and technically feasible for large-scale preparation of high-performance nanocomposites; it opens up new opportunities for exploiting the unique properties of graphene or even other nanofillers for a wide range of applications.

Thermal conversion of an iron nitride-silicon nitride precursor into a ferromagnetic nanocomposite

NASA Astrophysics Data System (ADS)

Maya, L.; Thompson, J. R.; Song, K. J.; Warmack, R. J.

1998-01-01

Iron nitride films, FeN, in a pure form and in the form of a nanocomposite in silicon nitride were prepared by reactive sputtering using iron or iron disilicide, respectively, as targets in a nitrogen plasma. Iron nitride decomposes into the elements by heating in vacuum to 800 °C. Intermediate phases such as Fe2N or Fe4N form at lower temperatures. The nanocomposites contain the iron phases as particles with an average size of ˜5 nm dispersed in the amorphous silicon nitride matrix. The magnetic properties of the nanocomposites were established. The precursor FeN-Si3N4 film is paramagnetic, while the Fe-Si3N4, obtained by heating in vacuum, is ferromagnetic and shows typical superparamagnetic behavior. These films are of interest as recording media with superior chemical and mechanical stability and may be encoded by localized heating.

Powder compression mechanics of spray-dried lactose nanocomposites.

PubMed

Hellrup, Joel; Nordström, Josefina; Mahlin, Denny

2017-02-25

The aim of this study was to investigate the structural impact of the nanofiller incorporation on the powder compression mechanics of spray-dried lactose. The lactose was co-spray-dried with three different nanofillers, that is, cellulose nanocrystals, sodium montmorillonite and fumed silica, which led to lower micron-sized nanocomposite particles with varying structure and morphology. The powder compression mechanics of the nanocomposites and physical mixtures of the neat spray-dried components were evaluated by a rational evaluation method with compression analysis as a tool, using the Kawakita equation and the Shapiro-Konopicky-Heckel equation. Particle rearrangement dominated the initial compression profiles due to the small particle size of the materials. The strong contribution of particle rearrangement in the materials with fumed silica continued throughout the whole compression profile, which prohibited an in-depth material characterization. However, the lactose/cellulose nanocrystals and the lactose/sodium montmorillonite nanocomposites demonstrated high yield pressure compared with the physical mixtures indicating increased particle hardness upon composite formation. This increase has likely to do with a reinforcement of the nanocomposite particles by skeleton formation of the nanoparticles. In summary, the rational evaluation of mechanical properties done by applying powder compression analysis proved to be a valuable tool for mechanical evaluation for this type of spray-dried composite materials, unless they demonstrate particle rearrangement throughout the whole compression profile. Copyright © 2016 Elsevier B.V. All rights reserved.

Microstructure and Properties of Polypropylene/Carbon Nanotube Nanocomposites

PubMed Central

Bikiaris, Dimitrios

2010-01-01

In the last few years, great attention has been paid to the preparation of polypropylene (PP) nanocomposites using carbon nanotubes (CNTs) due to the tremendous enhancement of the mechanical, thermal, electrical, optical and structural properties of the pristine material. This is due to the unique combination of structural, mechanical, electrical, and thermal transport properties of CNTs. However, it is well-known that the properties of polymer-based nanocomposites strongly depend on the dispersion of nanofillers and almost all the discussed properties of PP/CNTs nanocomposites are strongly related to their microstructure. PP/CNTs nanocomposites were, mainly, prepared by melt mixing and in situ polymerization. Young’s modulus, tensile strength and storage modulus of the PP/CNTs nanocomposites can be increased with increasing CNTs content due to the reinforcement effect of CNTs inside the polymer matrix. However, above a certain CNTs content the mechanical properties are reduced due to the CNTs agglomeration. The microstructure of nanocomposites has been studied mainly by SEM and TEM techniques. Furthermore, it was found that CNTs can act as nucleating agents promoting the crystallization rates of PP and the addition of CNTs enhances all other physical properties of PP. The aim of this paper is to provide a comprehensive review of the existing literature related to PP/CNTs nanocomposite preparation methods and properties studies.

Poly (lactic-co-glycolic acid) particles prepared by microfluidics and conventional methods. Modulated particle size and rheology.

PubMed

Perez, Aurora; Hernández, Rebeca; Velasco, Diego; Voicu, Dan; Mijangos, Carmen

2015-03-01

Microfluidic techniques are expected to provide narrower particle size distribution than conventional methods for the preparation of poly (lactic-co-glycolic acid) (PLGA) microparticles. Besides, it is hypothesized that the particle size distribution of poly (lactic-co-glycolic acid) microparticles influences the settling behavior and rheological properties of its aqueous dispersions. For the preparation of PLGA particles, two different methods, microfluidic and conventional oil-in-water emulsification methods were employed. The particle size and particle size distribution of PLGA particles prepared by microfluidics were studied as a function of the flow rate of the organic phase while particles prepared by conventional methods were studied as a function of stirring rate. In order to study the stability and structural organization of colloidal dispersions, settling experiments and oscillatory rheological measurements were carried out on aqueous dispersions of PLGA particles with different particle size distributions. Microfluidics technique allowed the control of size and size distribution of the droplets formed in the process of emulsification. This resulted in a narrower particle size distribution for samples prepared by MF with respect to samples prepared by conventional methods. Polydisperse samples showed a larger tendency to aggregate, thus confirming the advantages of microfluidics over conventional methods, especially if biomedical applications are envisaged. Copyright © 2014 Elsevier Inc. All rights reserved.

Preparation and Characterization of Polyimide Nanocomposites

NASA Technical Reports Server (NTRS)

Orwoll, Robert A.

2002-01-01

Many properties of polymeric materials can be enhanced by dispersing small quantities of clay nanocomposites throughout the polymer. Among the enhancements are increases in modulus and resistance to erosion by atomic oxygen and reductions in thermal expansivity, gas permeability, and flammability. To achieve the full extent of enhancement with these polymer-clay nanocomposites, the clay nanoparticles, which have thicknesses of only one-to-several nanometers and lengths and widths of hundreds of nanometers to micrometers, must be exfoliated one from another and then individually dispersed throughout the polymer. This dispersion is achieved only after alkali metal cations (usually Na(+)) that reside on the surfaces of the nanoparticles have been replaced by organocations (typically a quaternary amine cation). This renders the surface of the nanoparticle a more hospitable interface for the organic polymer matrix. Following the cation exchange, the organic clay is either mixed directly into the polymer or is dispersed in monomer which is later polymerized around the nanoparticle.

Atomic-level study on mechanical properties and strengthening mechanisms of Al/SiC nano-composites

NASA Astrophysics Data System (ADS)

Huo, Shiyan; Xie, Lijing; Xiang, Junfeng; Pang, Siqin; Hu, Fang; Umer, Usama

2018-02-01

Molecular dynamics (MD) models for the study on the mechanical properties of β-SiC particles-reinforced aluminum matrix nano-composites (Al/SiC nano-composites) are established. The nano-composites in the model are fabricated by a powder metallurgy (P/M) process, followed by a hot isostatic pressing and then annealing to room temperature. The fabricated nano-composites have dense and even distributions of reinforced particles. Then representative volume elements (RVEs) of the fabricated nano-composites are built by adding periodic boundary conditions (PBCs). In this way, RVEs with different volume fractions and particle sizes of SiC are produced and put into the simulation of tension tests. The elasticity and strength in single axial tension obtained from MD analysis are in good agreement with those calculated according to the rule of mixture. It is found that the dispersion of SiC particles into the Al matrix leads to a significant enhancement in the strength of nano-composites compared to pure Al, which is also dramatically affected by both the volume fraction and particle size. Additionally, the Al/SiC nano-composites with finer SiC particles get greater enhancement in the mechanical behavior than those with coarser ones. MD analysis clearly shows the contributions of load-transfer effect, thermal mismatch strengthening and Orowan strengthening to the strengthening of Al/SiC nano-composites.

Toughening Mechanisms in Silica-Filled Epoxy Nanocomposites

NASA Astrophysics Data System (ADS)

Patel, Binay S.

Epoxies are widely used as underfill resins throughout the microelectronics industry to mechanically couple and protect various components of flip-chip assemblies. Generally rigid materials largely surround underfill resins. Improving the mechanical and thermal properties of epoxy resins to better match those of their rigid counterparts can help extend the service lifetime of flip-chip assemblies. Recently, researchers have demonstrated that silica nanoparticles are effective toughening agents for lightly-crosslinked epoxies. Improvements in the fracture toughness of silica-filled epoxy nanocomposites have primarily been attributed to two toughening mechanisms: particle debonding with subsequent void growth and matrix shear banding. Various attempts have been made to model the contribution of these toughening mechanisms to the overall fracture energy observed in silica-filled epoxy nanocomposites. However, disparities still exist between experimental and modeled fracture energy results. In this dissertation, the thermal, rheological and mechanical behavior of eight different types of silica-filled epoxy nanocomposites was investigated. Each nanocomposite consisted of up to 10 vol% of silica nanoparticles with particle sizes ranging from 20 nm to 200 nm, with a variety of surface treatments and particle structures. Fractographical analysis was conducted with new experimental approaches in order to accurately identify morphological evidence for each proposed toughening mechanism. Overall, three major insights into the fracture behavior of real world silica-filled epoxy nanocomposites were established. First, microcracking was observed as an essential toughening mechanism in silica-filled epoxy nanocomposites. Microcracking was observed on the surface and subsurface of fractured samples in each type of silica-filled epoxy nanocomposite. The additional toughening contribution of microcracking to overall fracture energy yielded excellent agreement between experimental

Long term determination of dopamine and uric acid in the presence of ascorbic acid using ytterbia/reduced graphene oxide nanocomposite prepared through a sonochemical route

NASA Astrophysics Data System (ADS)

Jafari, Hossein; Ganjali, Mohammad Reza; Dezfuli, Amin Shiralizadeh; Faridbod, Farnoush

2018-01-01

Decoration of reduced graphene oxide (RGO) with nano-size inorganic particles creates a class of composites with considerably improved characteristics. Improvements in the function of electrochemical energy-storage devices, catalysts and sensors using such particles, have hence attracted a great deal of interest to the area. This manuscript tends to report the results of the research on the application of a sonochemical route for anchoring nano-sized Yb2O3 (Ytterbia) particles, on sheets of RGO. The anchoring phenomenon is based on the self-assembly of the Yb2O3 nano-particles under sonochemical treatments in an ultrasonic bath. To evaluate the method, the produced Yb2O3-RGO nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and field-emission scanning electron microscopy (FE-SEM), which proved the uniform distribution of the nano-particles on the RGO sheets. Additionally, the Yb2O3-RGO nano-composites were evaluated through cyclic voltammetry (CV), to assess the potentials of their application in electrochemical devices. The high activity of the produced Yb2O3-RGO nanocomposites can be attributed to the synergistic effect between Yb2O3 and RGO as well as the porous structure of the nanocomposite. Due to their stability, electrocatalytic properties and large accessible surface area, the low detection limit sensor is usable for long term usages in blood serum and wide linear dynamic range. There are linear relationships between current intensities and concentrations in the region 0.3-800 μM dopamine (DA), and 0.2-210 μM uric acid (UA), and the limits of detection (LOD) (S/N = 3) are down to 0.02 μM and 0.01 μM for DA and UA, respectively in 0.5 mM solution of ascorbic acid.

Direct synthesis and morphological characterization of gold-dendrimer nanocomposites prepared using PAMAM succinamic acid dendrimers: preliminary study of the calcification potential.

PubMed

Vasile, E; Serafim, A; Petre, D; Giol, D; Dubruel, P; Iovu, H; Stancu, I C

2014-01-01

Gold-dendrimer nanocomposites were obtained for the first time by a simple colloidal approach based on the use of polyamidoamine dendrimers with succinamic acid terminal groups and dodecanediamine core. Spherical and highly crystalline nanoparticles with dimensions between 3 nm and 60 nm, and size-polydispersity depending on the synthesis conditions, have been generated. The influence of the stoichiometric ratio and the structural and architectural features of the dendrimers on the properties of the nanocomposites has been described. The self-assembling behaviour of these materials produces gold-dendrimer nanostructured porous networks with variable density, porosity, and composition. The investigations of the reaction systems, by TEM, at two postsynthesis moments, allowed to preliminary establish the control over the properties of the nanocomposite products. Furthermore, this study allowed better understanding of the mechanism of nanocomposite generation. Impressively, in the early stages of the synthesis, the organization of gold inside the dendrimer molecules has been evidenced by micrographs. Growth and ripening mechanisms further lead to nanoparticles with typical characteristics. The potential of such nanocomposite particles to induce calcification when coating a polymer substrate was also investigated.

Direct Synthesis and Morphological Characterization of Gold-Dendrimer Nanocomposites Prepared Using PAMAM Succinamic Acid Dendrimers: Preliminary Study of the Calcification Potential

PubMed Central

Vasile, E.; Serafim, A.; Petre, D.; Giol, D.; Dubruel, P.; Iovu, H.; Stancu, I. C.

2014-01-01

Gold-dendrimer nanocomposites were obtained for the first time by a simple colloidal approach based on the use of polyamidoamine dendrimers with succinamic acid terminal groups and dodecanediamine core. Spherical and highly crystalline nanoparticles with dimensions between 3 nm and 60 nm, and size-polydispersity depending on the synthesis conditions, have been generated. The influence of the stoichiometric ratio and the structural and architectural features of the dendrimers on the properties of the nanocomposites has been described. The self-assembling behaviour of these materials produces gold-dendrimer nanostructured porous networks with variable density, porosity, and composition. The investigations of the reaction systems, by TEM, at two postsynthesis moments, allowed to preliminary establish the control over the properties of the nanocomposite products. Furthermore, this study allowed better understanding of the mechanism of nanocomposite generation. Impressively, in the early stages of the synthesis, the organization of gold inside the dendrimer molecules has been evidenced by micrographs. Growth and ripening mechanisms further lead to nanoparticles with typical characteristics. The potential of such nanocomposite particles to induce calcification when coating a polymer substrate was also investigated. PMID:24600316

Partial discharge characteristics of polymer nanocomposite materials in electrical insulation: a review of sample preparation techniques, analysis methods, potential applications, and future trends.

PubMed

Izzati, Wan Akmal; Arief, Yanuar Z; Adzis, Zuraimy; Shafanizam, Mohd

2014-01-01

Polymer nanocomposites have recently been attracting attention among researchers in electrical insulating applications from energy storage to power delivery. However, partial discharge has always been a predecessor to major faults and problems in this field. In addition, there is a lot more to explore, as neither the partial discharge characteristic in nanocomposites nor their electrical properties are clearly understood. By adding a small amount of weight percentage (wt%) of nanofillers, the physical, mechanical, and electrical properties of polymers can be greatly enhanced. For instance, nanofillers in nanocomposites such as silica (SiO2), alumina (Al2O3) and titania (TiO2) play a big role in providing a good approach to increasing the dielectric breakdown strength and partial discharge resistance of nanocomposites. Such polymer nanocomposites will be reviewed thoroughly in this paper, with the different experimental and analytical techniques used in previous studies. This paper also provides an academic review about partial discharge in polymer nanocomposites used as electrical insulating material from previous research, covering aspects of preparation, characteristics of the nanocomposite based on experimental works, application in power systems, methods and techniques of experiment and analysis, and future trends.

Partial Discharge Characteristics of Polymer Nanocomposite Materials in Electrical Insulation: A Review of Sample Preparation Techniques, Analysis Methods, Potential Applications, and Future Trends

PubMed Central

Izzati, Wan Akmal; Adzis, Zuraimy; Shafanizam, Mohd

2014-01-01

Polymer nanocomposites have recently been attracting attention among researchers in electrical insulating applications from energy storage to power delivery. However, partial discharge has always been a predecessor to major faults and problems in this field. In addition, there is a lot more to explore, as neither the partial discharge characteristic in nanocomposites nor their electrical properties are clearly understood. By adding a small amount of weight percentage (wt%) of nanofillers, the physical, mechanical, and electrical properties of polymers can be greatly enhanced. For instance, nanofillers in nanocomposites such as silica (SiO2), alumina (Al2O3) and titania (TiO2) play a big role in providing a good approach to increasing the dielectric breakdown strength and partial discharge resistance of nanocomposites. Such polymer nanocomposites will be reviewed thoroughly in this paper, with the different experimental and analytical techniques used in previous studies. This paper also provides an academic review about partial discharge in polymer nanocomposites used as electrical insulating material from previous research, covering aspects of preparation, characteristics of the nanocomposite based on experimental works, application in power systems, methods and techniques of experiment and analysis, and future trends. PMID:24558326

A novel synthesis of SrCO3-SrTiO3 nanocomposites with high photocatalytic activity

NASA Astrophysics Data System (ADS)

Márquez-Herrera, A.; Ovando-Medina, Víctor M.; Castillo-Reyes, Blanca E.; Meléndez-Lira, M.; Zapata-Torres, M.; Saldaña, N.

2014-12-01

The results of the production and characterization of SrCO3-SrTiO3 nanocomposites as a promising candidate for efficient photocatalysts are reported. The production is based on a novelty route employing the solvothermal method with strontium chloride and titanium (IV) butoxide as the precursor solutions. The effect on the properties of the nanocomposites due to changes in the content of SrCO3 and SrTiO3 is reported. The as-prepared materials were tested in the photodegradation of methylene blue dye in aqueous solutions under the solar light. The reported route allows the production of SrCO3-SrTiO3 nanocomposites with particle sizes ranging between 18 and 29 nm. The SrCO3-SrTiO3 nanocomposites obtained with 19 % of SrCO3 phase and 81 % of SrTiO3 (M10) can achieve 94 and 97 % of dye photodegradation after 30 and 120 min, respectively.

Acquisition of Preparative Gel Permeation Chromatography for Research and Education in Energy Conversion and Nanocomposites

DTIC Science & Technology

2017-04-19

AFRL-AFOSR-VA-TR-2017-0090 Acquisition of Preparative Gel Permeation Chromatography for Research and Education in Energy Conversion and...Nanocomposites Zhiqun Lin GEORGIA TECH RESEARCH CORPORATION 505 10TH ST NW ATLANTA, GA 30318-5775 04/19/2017 Final Report DISTRIBUTION A: Distribution approved...for public release. Air Force Research Laboratory AF Office Of Scientific Research (AFOSR)/RTB2 4/21/2017https://livelink.ebs.afrl.af.mil/livelink

Synthesis and applications of MANs/poly(MMA-co-BA) nanocomposite latex by miniemulsion polymerization

PubMed Central

Chen, Huayao; Zhou, Xinhua; Gunasekaran, Sundaram

2017-01-01

We have synthesized core-shell structured 3-methacryloxypropyltrimethoxysilane (MPS) functionalized antimony-doped tin oxide nanoparticles (MANs)–poly(methyl methacrylate-co-butyl acrylate) (PMMA-co-BA, PMB) nanocomposite latex particles via miniemulsion polymerization method. Polymerizable anionic surfactant DNS-86 (allyloxy polyoxyethylene(10) nonyl ammonium sulfate) was first introduced to synthesize core-shell nanocomposite. The morphologies of synthesized MANs and MANs/PMB latex nanocomposite particles were studied with transmission electron microscopy, which revealed particles, on average 70 nm in size, with a core-shell structure. Owing to the uniformity and hydrophobicity of MANs, the MANs-embedded PMB latex nanocomposite can be tailored more precisely than other nanoparticles-embedded nanocomposites. Films incorporating 10 wt% of MANs in the MAN/PMB latex nanocomposite exhibit good transmittance in the visible region, and excellent opacity in the near infrared region. The MANs/PMB nanocomposite film also appears suitable for heat insulation applications. PMID:29291076

One-step, simple, and green synthesis of tin dioxide/graphene nanocomposites and their application to lithium-ion battery anodes

NASA Astrophysics Data System (ADS)

Jiang, Zaixing; Zhang, Dongjie; Li, Yue; Cheng, Hao; Wang, Mingqiang; Wang, Xueqin; Bai, Yongping; Lv, Haibao; Yao, Yongtao; Shao, Lu; Huang, Yudong

2014-10-01

Graphene with extraordinary thermal, mechanical and electrical properties offers possibilities in a variety of applications. Recent advances in the synthesis of graphene composites using supercritical fluids are highlighted. Supercritical fluids exhibit unique features for the synthesis of composites due to its low viscosity, high diffusivity, near-zero surface tension, and tunability. Here, we report the preparation of tin dioxide (SnO2)/graphene nanocomposite through supercritical CO2 method. It demonstrates that the SnO2 nanoparticles are homogeneously dispersed on the surface of graphene sheets with a particle size of 2.3-2.6 nm. The SnO2/graphene nanocomposites exhibit higher lithium storage capacity and better cycling performance compared to that of the similar CNT nanocomposites. The reported synthetic procedure is straightforward, green and inexpensive. And it may be readily adopted to produce large quantities of graphene based nanocomposites.

Organic-Inorganic Hydrophobic Nanocomposite Film with a Core-Shell Structure

PubMed Central

Liu, Peng; Chen, Ying; Yu, Zhiwu

2016-01-01

A method to prepare novel organic-inorganic hydrophobic nanocomposite films was proposed by a site-specific polymerization process. The inorganic part, the core of the nanocomposite, is a ternary SiO2–Al2O3–TiO2 nanoparticles, which is grafted with methacryloxy propyl trimethoxyl silane (KH570), and wrapped by fluoride and siloxane polymers. The synthesized samples are characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrscopy, X-ray diffractometry (XRD), contact angle meter (CA), and scanning electron microscope (SEM). The results indicate that the novel organic-inorganic hydrophobic nanocomposite with a core-shell structure was synthesized successfully. XRD analysis reveals the nanocomposite film has an amorphous structure, and FTIR analysis indicates the nanoparticles react with a silane coupling agent (methacryloxy propyl trimethoxyl silane KH570). Interestingly, the morphology of the nanoparticle film is influenced by the composition of the core. Further, comparing with the film synthesized by silica nanoparticles, the film formed from SiO2–Al2O3–TiO2 nanoparticles has higher hydrophobic performance, i.e., the contact angle is greater than 101.7°. In addition, the TEM analysis reveals that the crystal structure of the particles can be changed at high temperatures. PMID:28774141

Melatonin potentiates "inside-out" nano-thermotherapy in human breast cancer cells: a potential cancer target multimodality treatment based on melatonin-loaded nanocomposite particles.

PubMed

Xie, Wensheng; Gao, Qin; Wang, Dan; Wang, Wei; Yuan, Jie; Guo, Zhenhu; Yan, Hao; Wang, Xiumei; Sun, Xiaodan; Zhao, Lingyun

2017-01-01

With the wide recognition of oncostatic effect of melatonin, the current study proposes a potential breast cancer target multimodality treatment based on melatonin-loaded magnetic nanocomposite particles (Melatonin-MNPs). Melatonin-MNPs were fabricated by the single emulsion solvent extraction/evaporation method. Based on the facilitated transport of melatonin by the GLUT overexpressed on the cell membrane, such Melatonin-MNPs can be more favorably uptaken by MCF-7 cells compared with the melatonin-free nanocomposite particles, which indicates the cancer targeting ability of melatonin molecule. Inductive heating can be generated by exposure to the Melatonin-MNPs internalized within cancer cells under alternative magnetic field, so as to achieve the "inside-out" magnetic nano-thermotherapy. In addition to demonstrating the superior cytotoxic effect of such nano-thermotherapy over the conventional exogenous heating by metal bath, more importantly, the sustainable release of melatonin from the Melatonin-MNPs can be greatly promoted upon responsive to the magnetic heating. The multimodality treatment based on Melatonin-MNPs can lead to more significant decrease in cell viability than any single treatment, suggesting the potentiated effect of melatonin on the cytotoxic response to nano-thermotherapy. This study is the first to fabricate the precisely engineered melatonin-loaded multifunctional nanocomposite particles and demonstrate the potential in breast cancer target multimodality treatment.

High Temperature Thermosetting Polyimide Nanocomposites Prepared with Reduced Charge Organoclay

NASA Technical Reports Server (NTRS)

Campbell, Sandi; Liang, Margaret I.

2005-01-01

The naturally occurring sodium and calcium cations found in bentonite clay galleries were exchanged with lithium cations. Following the cation exchange, a series of reduced charge clays were prepared by heat treatment of the lithium bentonite at 130 C, 150 C, or 170 C. Inductively coupled plasma (ICP) analysis showed that heating the lithium clay at elevated temperatures reduced its cation exchange capacity. Ion exchange of heat-treated clays with either a protonated alkyl amine or a protonated aromatic diamine resulted in decreasing amounts of the organic modifier incorporated into the lithium clay. The level of silicate dispersion in a thermosetting polyimide matrix was dependent upon the temperature of Li-clay heat treatment as well as the organic modification. In general, clays treated at 150 C or 170 C, and exchanged with protonated octadcylamine or protonated 2,2'-dimethlybenzidine (DMBZ) showed a higher degree of dispersion than clays treated at 130 C, or exchanged with protonated dodecylamine. Dynamic mechanical analysis showed little change in the storage modulus or T(sub g) of the nanocomposites compared to the base resin. However, long term isothermal aging of the samples showed a significant decrease in the resin oxidative weight loss. Nanocomposite samples aged in air for 1000 hours at 288 C showed of to a decrease in weight loss compared to that of the base resin. This again was dependent on the temperature at which the Li-clay was heated and the choice of organic modification.

Effects of natural zeolite and ferric oxide to electromagnetic and reflection loss properties of polyurethane nanocomposite

NASA Astrophysics Data System (ADS)

Gultom, G.; Wirjosentono, B.; Ginting, M.; Sebayang, K.

2017-07-01

Microwave-absorptive polymeric composite materials are becoming important to protect interference of any communication systems due to increasing use of microwave-inducing devices. In this work, the microwave-absorptive polyurethane nanocomposites were prepared using natural zeolites of Sarulla North Sumatra and commercial ferric oxide as fillers. Weight ratios of the polyurethane to natural zeolite and ferric oxide were varied (90%:6%:4%; 80%:12%:8%; 70%:24%:6%) by weight. The fillers were prepared using ball milling technique and characterized for their particle size distributions using Particle Size Analyzer. The nanocomposites, prepared using in-situ reaction of polyethylene glycol, toluene diisocyanate and fillers. The complex permittivity (ε’and ε”) and complex permeability (μ’ and μ”) as electromagnetic properties were calculated using NRW method after collecting real and imaginary S parameter using Vector Network Analyzer measurement at X band frequency. Results show ratio of the fillers will affect the permeability, permittivity and reflection loss of the materials. The best reflection loss was shown -40.588 dB (>99 % absorption) at ratio for polyurethane : nanozeolite : ferric oxide (80%:12%:8%) by weight observed at 10.92 GHz. According to the measurement and calculation was shown the polyurethane filled with natural nanozeolite and ferric oxide is a good electromagnetic wave attenuation material.

Preparation and characterization of a poly (1, 4-phenylenevinylene) derivative-based hybrid thin film nanocomposites with enhanced performance

NASA Astrophysics Data System (ADS)

Belhaj, Marwa; Jemmeli, Dhouha; Dridi, Cherif; Ben Salem, Balkiss; Jaballah, Najmeddine; Majdoub, Mustapha; Yatskiv, Roman; Grym, Jan

2018-05-01

In this study, a poly (1, 4-phenylenevinylene) derivative (PPV-C6) was synthesized via Gilch polycondensation, and its electrochemical and optical characteristics were determined by cyclic voltammetry analysis, ultraviolet-visible, and photoluminescence spectroscopy. The polymer exhibited semiconductor behavior with an optical band gap of about 2.02 eV. Thin-film hybrid nanocomposites were prepared based on PPV-C6 with a large range of concentrations of sol-gel synthesized surfactant-free ZnO nanoparticles (n-ZnO). We investigated the photophysical properties of nanocomposites with different weight ratios of n-ZnO. The optical absorption spectra of PPV-C6: n-ZnO nanocomposites exhibited moderate variation in terms of the optical band gap energy with respect to the pristine polymer. Photoluminescence spectra indicated that the optimum n-ZnO concentration was about 50 wt% to achieve photoluminescence quenching, which corresponded to the most homogeneous surface and efficient charge transfer due to optimal exciton dissociation. We established good correlations between the investigated properties.

Preparation and Application of Hollow Silica/magnetic Nanocomposite Particle

NASA Astrophysics Data System (ADS)

Wang, Cheng-Chien; Lin, Jing-Mo; Lin, Chun-Rong; Wang, Sheng-Chang

The hollow silica/cobalt ferrite (CoFe2O4) magnetic microsphere with amino-groups were successfully prepared via several steps, including preparing the chelating copolymer microparticles as template by soap-free emulsion polymerization, manufacturing the hollow cobalt ferrite magnetic microsphere by in-situ chemical co-precipitation following calcinations, and surface modifying of the hollow magnetic microsphere by 3-aminopropyltrime- thoxysilane via the sol-gel method. The average diameter of polymer microspheres was ca. 200 nm from transmission electron microscope (TEM) measurement. The structure of the hollow magnetic microsphere was characterized by using TEM and scanning electron microscope (SEM). The spinel-type lattice of CoFe2O4 shell layer was identified by using XRD measurement. The diameter of CoFe2O4 crystalline grains ranged from 54.1 nm to 8.5 nm which was estimated by Scherrer's equation. Additionally, the hollow silica/cobalt ferrite microsphere possesses superparamagnetic property after VSM measurement. The result of BET measurement reveals the hollow magnetic microsphere which has large surface areas (123.4m2/g). After glutaraldehyde modified, the maximum value of BSA immobilization capacity of the hollow magnetic microsphere was 33.8 mg/g at pH 5.0 buffer solution. For microwave absorption, when the hollow magnetic microsphere was compounded within epoxy resin, the maximum reflection loss of epoxy resins could reach -35dB at 5.4 GHz with 1.9 mm thickness.

Preparation of melt-spun antimicrobially modified LDH/polyolefin nanocomposite fibers.

PubMed

Kutlu, Burak; Schröttner, Percy; Leuteritz, Andreas; Boldt, Regine; Jacobs, Enno; Heinrich, Gert

2014-08-01

Layered double hydroxide (LDH) was synthesized and organically modified with camphorsulfonic acid (CSA) and ciprofloxacin. The thermal stability of CSA was improved remarkably under LDH shielding. A minimal inhibitory concentration of free CSA against tested bacteria was determined in order to define the essential quantity in LDH modification. The modified LDHs were melt-compounded with high density polyethylene and the prepared nanocomposites were further melt-spun using a piston-type spinning device. The melt-spun fibers were tested for their antimicrobial activity against Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa, Enterobacter cloacae, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pyogenes. CSA integrated fibers show susceptibility against Gram-positive bacteria and ciprofloxacin integrated fibers showed activity against both Gram-positive and Gram-negative bacteria. Copyright © 2014 Elsevier B.V. All rights reserved.

Biodegradable nanocomposite coatings accelerate bone healing: In vivo evaluation

PubMed Central

Mehdikhani-Nahrkhalaji, Mehdi; Fathi, Mohammad Hossein; Mortazavi, Vajihesadat; Mousavi, Sayed Behrouz; Akhavan, Ali; Haghighat, Abbas; Hashemi-Beni, Batool; Razavi, Sayed Mohammad; Mashhadiabbas, Fatemeh

2015-01-01

Background: The aim of this study was to evaluate the interaction of bioactive and biodegradable poly (lactide-co-glycolide)/bioactive glass/hydroxyapatite (PBGHA) and poly (lactide-co-glycolide)/bioactive glass (PBG) nanocomposite coatings with bone. Materials and Methods: Sol-gel derived 58S bioactive glass nanoparticles, 50/50 wt% poly (lactic acid)/poly (glycolic acid) and hydroxyapatite nanoparticles were used to prepare the coatings. The nanocomposite coatings were characterized by scanning electron microscopy, X-ray diffraction and atomic force microscopy. Mechanical stability of the prepared nanocomposite coatings was studied during intramedullary implantation of coated Kirschner wires (K-wires) into rabbit tibia. Titanium mini-screws coated with nanocomposite coatings and without coating were implanted intramedullary in rabbit tibia. Bone tissue interaction with the prepared nanocomposite coatings was evaluated 30 and 60 days after surgery. The non-parametric paired Friedman and Kruskal-Wallis tests were used to compare the samples. For all tests, the level of significance was P < 0.05. Results: The results showed that nanocomposite coatings remained stable on the K-wires with a minimum of 96% of the original coating mass. Tissue around the coated implants showed no adverse reactions to the coatings. Woven and trabecular bone formation were observed around the coated samples with a minimum inflammatory reaction. PBG nanocomposite coating induced more rapid bone healing than PBGHA nanocomposite coating and titanium without coating (P < 0.05). Conclusion: It was concluded that PBG nanocomposite coating provides an ideal surface for bone formation and it could be used as a candidate for coating dental and orthopedic implants. PMID:25709681

Pickering Particles Prepared from Food Waste

PubMed Central

Gould, Joanne; Garcia-Garcia, Guillermo; Wolf, Bettina

2016-01-01

In this paper, we demonstrate the functionality and functionalisation of waste particles as an emulsifier for oil-in-water (o/w) and water-in-oil (w/o) emulsions. Ground coffee waste was chosen as a candidate waste material due to its naturally high content of lignin, a chemical component imparting emulsifying ability. The waste coffee particles readily stabilised o/w emulsions and following hydrothermal treatment adapted from the bioenergy field they also stabilised w/o emulsions. The hydrothermal treatment relocated the lignin component of the cell walls within the coffee particles onto the particle surface thereby increasing the surface hydrophobicity of the particles as demonstrated by an emulsion assay. Emulsion droplet sizes were comparable to those found in processed foods in the case of hydrophilic waste coffee particles stabilizing o/w emulsions. These emulsions were stable against coalescence for at least 12 weeks, flocculated but stable against coalescence in shear and stable to pasteurisation conditions (10 min at 80 °C). Emulsion droplet size was also insensitive to pH of the aqueous phase during preparation (pH 3–pH 9). Stable against coalescence, the water droplets in w/o emulsions prepared with hydrothermally treated waste coffee particles were considerably larger and microscopic examination showed evidence of arrested coalescence indicative of particle jamming at the surface of the emulsion droplets. Refinement of the hydrothermal treatment and broadening out to other lignin-rich plant or plant based food waste material are promising routes to bring closer the development of commercially relevant lignin based food Pickering particles applicable to emulsion based processed foods ranging from fat continuous spreads and fillings to salad dressings. PMID:28773909

In situ chemical oxidative polymerization preparation of poly(3,4-ethylenedioxythiophene)/graphene nanocomposites with enhanced thermoelectric performance.

PubMed

Xu, Kongli; Chen, Guangming; Qiu, Dong

2015-05-01

Three different in situ chemical oxidative polymerization routes, that is, (A) spin-coating and subsequent liquid layer polymerization, (B) spin-coating followed by vapor phase polymerization, and (C) in situ polymerization and then post-treatment by immersion in ethylene glycol (EG), have been developed to achieve poly(3,4-ethylenedioxythiophene)/reduced graphene oxide (PEDOT/rGO) nanocomposites. As demonstrated by scanning electron microscopic and energy-dispersive X-ray spectroscopic techniques, PEDOT has been successfully coated on the surface of the rGO nanosheets by each of the three preparation routes. Importantly, all of the nanocomposites display a greatly enhanced thermoelectric performance (power factors) relative to those of the corresponding neat PEDOT. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of calcination temperature on the microstructure and electronic properties of TiO2-ZnO nanocomposites and implications on photocatalytic activity

NASA Astrophysics Data System (ADS)

Menon, N. Gayathri; Tatiparti, Sankara Sarma V.; Mukherji, Suparna

2018-04-01

TiO2-ZnO nanocomposites with a constant Ti:Zn molar ratio of 1:0.1 were prepared via sol-gel process followed by calcination at 300, 400, 500, 600, and 700 °C. The structural and compositional characterizations of these nanocomposites were performed through XRD, FTIR, SEM, and EDAX. Bandgap was measured using DRS. Photocatalytic performance of the nanocomposites was evaluated by decolorization of methyl orange dye under UV and visible irradiation with and without aeration. The results showed that increase in calcination temperature resulted in nanocomposites with well-defined morphology. Although the particle size increased with increase in calcination temperature, the crystallinity of the particles also increased, resulting in enhanced photocatalytic activity. A temperature-dependent anatase-to-rutile phase transformation was observed in TiO2-ZnO nanocomposite beyond 600 °C. The calcination temperature influenced both dye adsorption on the nanocomposites and also dye decolorization by photocatalysis. Even when present at low molar concentration, ZnO in the nanocomposite caused sufficient decrease in bandgap (2.6 eV) at temperatures as low as 400 °C, such that visible irradiation could cause dye decolorization. However, the best decolorization performance was observed in the presence of the nanocomposite calcined at 600 °C. Aerated systems showed better performance in all cases. Desorption of the dye remaining adsorbed on the nanocomposite at the end of the photocatalytic reaction, confirmed that adsorption accounted for only 6.6 and 3% of dye removal in the nanocomposites calcined at 600 °C with UV and visible irradiation, respectively. However, in other systems, ignoring adsorption may cause significant overestimation in photocatalytic loss of dye from the system.

Electrospun nanocomposite fibrous polymer electrolyte for secondary lithium battery applications

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

Padmaraj, O.; Rao, B. Nageswara; Jena, Paramananda

2014-04-24

Hybrid nanocomposite [poly(vinylidene fluoride -co- hexafluoropropylene) (PVdF-co-HFP)/magnesium aluminate (MgAl{sub 2}O{sub 4})] fibrous polymer membranes were prepared by electrospinning method. The prepared pure and nanocomposite fibrous polymer electrolyte membranes were soaked into the liquid electrolyte 1M LiPF{sub 6} in EC: DEC (1:1,v/v). XRD and SEM are used to study the structural and morphological studies of nanocomposite electrospun fibrous polymer membranes. The nanocomposite fibrous polymer electrolyte membrane with 5 wt.% of MgAl{sub 2}O{sub 4} exhibits high ionic conductivity of 2.80 × 10{sup −3} S/cm at room temperature. The charge-discharge capacity of Li/LiCoO{sub 2} coin cells composed of the newly prepared nanocomposite [(16more » wt.%) PVdF-co-HFP+(5 wt.%) MgAl{sub 2}O{sub 4}] fibrous polymer electrolyte membrane was also studied and compared with commercial Celgard separator.« less

Structural, morphological and Raman studies on hybridized PVDF/BaTiO3 nanocomposites

NASA Astrophysics Data System (ADS)

Rajamanickam, N.; Jayakumar, K.; Ramachandran, K.

2017-05-01

Hybridized nanocomposites of polyvinylidene fluoride (PVDF) and nano - barium titanate (BaTiO3) were prepared using the solution casting method for different concentrations of nano-BaTiO3 and were characterized by X-ray diffraction and scanning electron microscopy. The flower like structure for morphology was observed in SEM. Raman analysis showed that the modified BaTiO3 particles, due to higher specific surfaces, induce, predominantly, the crystallization of the electrically active β-phase of PVDF, while the initial micron size particles induce the formation of the most common but non-polar α-crystal form.

Novel concept for the preparation of gas selective nanocomposite membranes

NASA Astrophysics Data System (ADS)

Drobek, M.; Ayral, A.; Motuzas, J.; Charmette, C.; Loubat, C.; Louradour, E.; Dhaler, D.; Julbe, A.

2015-07-01

In this work we report on a novel concept for the preparation of gas selective composite membranes by a simple and robust synthesis protocol involving a controlled in-situpolycondensation of functional alkoxysilanes within the pores of a mesoporous ceramic matrix. This innovative approach targets the manufacture of thin nanocomposite membranes, allowing good compromise between permeability, selectivity and thermomechanical strength. Compared to simple infiltration, the synthesis protocol allows a controlled formation of gas separation membranes from size-adjusted functional alkoxysilanes by a chemical reaction within the mesopores of a ceramic support, without any formation of a thick and continuous layer on the support top-surface. Membrane permeability can thus be effectively controlled by the thickness and pore size of the mesoporous layer, and by the oligomers chain length. The as-prepared composite membranes are expected to possess a good mechanical and thermomechanical resistance and exhibit a thermally activated transport of He and H2 up to 150 °C, resulting in enhanced separation factors for specific gas mixtures e.g. FH2/CO ˜ 10; FH2/CO2 ˜ 3; FH2/CH4 ˜ 62.

Fracture behavior of polypropylene/clay nanocomposites.

PubMed

Chen, Ling; Wang, Ke; Kotaki, Masaya; Hu, Charmaine; He, Chaobin

2006-12-01

Polypropylene (PP)/clay nanocomposites have been prepared via a reactive compounding approach with an epoxy based masterbatch. Compared with PP and common PP/organoclay nanocomposites, the PP/clay nanocomposites based on epoxy/clay masterbatch have higher impact strength. The phenomenon can be attributed to the epoxy phase dispersed uniformly in the PP matrix, which may act as impact energy absorber and helps to form a large damage zone, thus a higher impact strength value is achieved.

Microstructure, Mechanical Properties, and Two-Body Abrasive Wear Behavior of Cold-Sprayed 20 vol.% Cubic BN-NiCrAl Nanocomposite Coating

NASA Astrophysics Data System (ADS)

Luo, Xiao-Tao; Yang, Er-Juan; Shang, Fu-Lin; Yang, Guan-Jun; Li, Chen-Xin; Li, Chang-Jiu

2014-10-01

20 vol.% cubic boron nitride (cBN) dispersoid reinforced NiCrAl matrix nanocomposite coating was prepared by cold spray using mechanically alloyed nanostructured composite powders. The as-sprayed nanocomposite coating was annealed at a temperature of 750 °C to enhance the inter-particle bonding. Microstructure of spray powders and coatings was characterized. Vickers microhardness of the coatings was measured. Two-body abrasive wear behavior of the coatings was examined on a pin-on-disk test. It was found that, in mechanically alloyed composite powders, nano-sized and submicro-sized cBN particles are uniformly distributed in nanocrystalline NiCrAl matrix. Dense coating was deposited by cold spray at a gas temperature of 650 °C with the same phases and grain size as those of the starting powder. Vickers hardness test yielded a hardness of 1063 HV for the as-sprayed 20 vol.% cBN-NiCrAl coating. After annealed at 750 °C for 5 h, unbonded inter-particle boundaries were partially healed and evident grain growth of nanocrystalline NiCrAl was avoided. Wear resistance of the as-sprayed 20 vol.% cBN-NiCrAl nanocomposite coating was comparable to the HVOF-sprayed WC-12Co coating. Annealing of the nanocomposite coating resulted in the improvement of wear resistance by a factor of ~33% owing to the enhanced inter-particle bonding. Main material removal mechanisms during the abrasive wear are also discussed.

Size reduction of submicron magnesium particles prepared by pulsed wire discharge

NASA Astrophysics Data System (ADS)

Duy Hieu, Nguyen; Tokoi, Yoshinori; Tanaka, Kenta; Sasaki, Toru; Suzuki, Tsuneo; Nakayama, Tadachika; Suematsu, Hisayuki; Niihara, Koichi

2018-02-01

In this study, the submicron magnesium particle size was reduced by adjusting ambient gas pressure and input energy. The mean diameter of the prepared particles was determined from transmission electron microscopy images. The geometric mean particle diameter decreased with increasing relative energy, which was defined as the charging energy divided by the evaporation energy of a wire. By this method, Mg particles with a geometric mean diameter of 41.9 nm were prepared. To our knowledge, they are the smallest passivated Mg particles prepared by any method.

Cost efficient PMMA/NG nanocomposites for electromagnetic interference shielding applications

NASA Astrophysics Data System (ADS)

Yadav, Prachi; Rattan, Sunita; Tripathi, Ambuj; Kumar, Sandeep

2017-06-01

Cost-efficient polymethylmethacrylate/exfoliated nanographite (PMMA/NG) nanocomposites were prepared through the melt blending technique. The crystalline size of NG in nanocomposites was estimated using Scherrer’s formula and was found to be in the range of 42.4-50.6 nm. Scanning electron micrographs showed the homogeneous dispersion of NG in the PMMA matrix. The thermal degradation temperature (T d) of nanocomposites was found to rise monotonically with increase in the loading of NG. Differential scanning calorimetry measurement showed a significant improvement in glass transition temperature (T g) from 97.2 °C for neat PMMA to 106.4 °C for 4.0 wt% PMMA/NG nanocomposites. DC electrical conductivity measurement revealed that the prepared nanocomposites exhibited a low percolation threshold of 0.45 vol%. The s-parameters (S 11 and S 21) were measured through vector network analyser and were explored in the estimation of electromagnetic interference (EMI) shielding effectiveness (SE). The EMI SE of 19.2 dB (~ 99% attenuation of incoming microwave (MW) power) was attained in the 4.0 wt% PMMA/NG nanocomposite at 12.7 GHz MW frequency. Moreover, the observed broadband EMI SE spectra indicate that the prepared nanocomposites can be employed in lightweight and low-cost commercial EMI shielding applications.

New opportunities in the preparation of nanocomposites for biomedical applications: revised mechanosynthesis of magnetite-silica nanocomposites

NASA Astrophysics Data System (ADS)

Scano, Alessandra; Cabras, Valentina; Marongiu, Francesca; Peddis, Davide; Pilloni, Martina; Ennas, Guido

2017-02-01

Environmentally friendly preparation of functionalized magnetite-silica (Fe3O4/SiO2) nanocomposites (NCs) with different SiO2 content (6, 20 and 50 wt%) using revised mechanosynthesis is reported. High-energy ball milling of α-Fe2O3, Si and SiO2 mixtures was followed by hydrolysis and condensation of 3-aminopropyl-triethoxysilane. X-ray powder diffraction and transmission electron microscopy showed the formation of almost spherical Fe3O4 nanocrystals with a narrow size distribution (4-6 nm) uniformly dispersed in the amorphous 100-200 nm SiO2 agglomerates. Scanning electron microscopy and energy dispersive spectroscopy were used to study the elemental distribution in the sample. Fourier transform infrared spectroscopy confirmed the NC surface functionalization with amino groups. Magnetic properties were also explored, indicating a homogeneous distribution of magnetic nanoparticles in the silica matrix.

Structural mechanical and antibacterial properties of HPMC/SF-AgNPs nanocomposite films

NASA Astrophysics Data System (ADS)

Harish, K. V.; Rao, B. Lakshmeesha; Asha, S.; Vipin, C.; Sangappa, Y.

2018-04-01

In the present study, Hydroxypropyl Methylcellulose (HPMC) pure and HPMC/SF-AgNPs biopolymer nanocomposite films were prepared by simple solution casting method. The prepared nanocomposite films were characterized using UV-Visible spectroscopy(UV-Vis), X-ray diffraction (XRD) measurements. The mechanical properties of HPMC/SF-AgNPs nanocomposites were found to be decrease with increase in the AgNP's concentrations. The HPMC/SF-AgNPs nanocomposites showed very good antibacterial activity against human pathogens P. aeruginosa, E.coli, and S.aureus.

Pd-Ni-MWCNT nanocomposite thin films: preparation and structure

NASA Astrophysics Data System (ADS)

Kozłowski, Mirosław; Czerwosz, ElŻbieta; Sobczak, Kamil

2017-08-01

The properties of nanocomposite palladium-nickel-multi-walled (Pd-Ni-MWCNT) films deposited on aluminum oxide (Al2O3) substrate have been prepared and investigated. These films were obtained by 3 step process consisted of PVD/CVD/PVD methods. The morphology and structure of the obtained films were characterized by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques at various stages of the film formation. EDX spectrometer was used to measurements of elements segregation in the obtained film. TEM and STEM (Scanning Transmission Electron Microscopy) observations showed MWCNTs decorated with palladium nanoparticles in the film obtained in the last step of film formation (final PVD process). The average size of the palladium nanoparticles observed both on MWCNTs and carbonaceous matrix does not exceed 5 nm. The research was conducted on the use of the obtained films as potential sensors of gases (e.g. H2, NH3, CO2) and bio-sensors or optical sensors.

Fabrication, characterization and gas sensing studies of PPy/MWCNT/SLS nanocomposite

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

Tiwari, D. C., E-mail: dctiwari2001@yahoo.com; Atri, Priyanka, E-mail: dctiwari2001@yahoo.com; Sharma, R.

2014-04-24

Multiwall carbon nanotubes (MWCNT) coated with polypyrrole nanocomposite was prepared by in-situ chemical oxidative polymerization method in the presence of surfactant (SLS). The scanning electron microscope (SEM) pictures indicate the core shell structure of PPy/MWCNT/SLS nanocomposite. Nature of the prepared material was investigated by X-ray diffraction spectroscopy. This nanocomposite shows the excellent gas sensing behaviour for ammonia gas at 150 ppm and 300 ppm levels.

In situ chemical synthesis of ruthenium oxide/reduced graphene oxide nanocomposites for electrochemical capacitor applications.

PubMed

Kim, Ji-Young; Kim, Kwang-Heon; Yoon, Seung-Beom; Kim, Hyun-Kyung; Park, Sang-Hoon; Kim, Kwang-Bum

2013-08-07

An in situ chemical synthesis approach has been developed to prepare ruthenium oxide/reduced graphene oxide (RGO) nanocomposites. It is found that as the C/O ratio increases, the number density of RuO2 nanoparticles decreases, because the chemical interaction between the Ru ions and the oxygen-containing functional groups provides anchoring sites where the nucleation of particles takes place. For electrochemical capacitor applications, the microwave-hydrothermal process was carried out to improve the conductivity of RGO in RuO2/RGO nanocomposites. The significant improvement in capacitance and high rate capability might result from the RuO2 nanoparticles used as spacers that make the interior layers of the reduced graphene oxide electrode available for electrolyte access.

Facile synthesis and magnetorheological properties of superparamagnetic CoFe2O4/GO nanocomposites

NASA Astrophysics Data System (ADS)

Wang, Guangshuo; Ma, Yingying; Dong, Xufeng; Tong, Yu; Zhang, Lina; Mu, Jingbo; Bai, Yongmei; Hou, Junxian; Che, Hongwei; Zhang, Xiaoliang

2015-12-01

In this study, cobalt ferrite/graphene oxide (CoFe2O4/GO) nanocomposites were synthesized successfully by a facile sonochemical method. The microstructure and physical properties of CoFe2O4/GO nanocomposites were investigated in detail by TEM, XRD and SQUID. It was found that GO nanosheets were fully exfoliated and decorated homogeneously with CoFe2O4 nanoparticles having diameters of 8∼15 nm. The field-dependent magnetization curve indicated superparamagnetic behavior of as-prepared CoFe2O4/GO with saturation magnetization (Ms) of 34.9 emu/g at room temperature. The ferrofluid was prepared by the obtained CoFe2O4/GO with 25 wt% particles and its magnetorheological (MR) properties were tested using a Physica MCR301 rheometer fitted with a magneto-rheological module. The CoFe2O4/GO-based ferrofluid exhibited typical MR effect with increasing viscosity, shear stress and yield stress depending on the applied magnetic field strength.

Morphological and mechanical properties of styrene butadiene rubber/nano copper nanocomposites

NASA Astrophysics Data System (ADS)

Harandi, Maryam Hadizadeh; Alimoradi, Fakhrodin; Rowshan, Gholamhussein; Faghihi, Morteza; Keivani, Maryam; Abadyan, Mohamadreza

In this research, rubber based nanocomposites with presence of nanoparticle has been studied. Styrene butadiene rubber (SBR)/nanocopper (NC) composites were prepared using two-roll mill method. Transmission electron microscope (TEM) and scanning electron microscope (SEM) images showed proper dispersion of NC in the SBR matrix without substantial agglomeration of nanoparticles. To evaluate the curing properties of nanocomposite samples, swelling and cure rheometric tests were conducted. Moreover, the rheological studies were carried out over a range of shear rates. The effect of NC particles was examined on the thermal behavior of the SBR using thermal gravimetric analysis (TGA). Furthermore, tensile tests were employed to investigate the capability of nanoparticles to enhance mechanical behavior of the compounds. The results showed enhancement in tensile properties with incorporation of NC to SBR matrix. Moreover, addition of NC increased shear viscosity and curing time of SBR composites.

Structure, mechanical and magnetic properties of Al4C3 reinforced nickel matrix nanocomposites

NASA Astrophysics Data System (ADS)

Chaudhari, Alok Kumar; Singh, Dhananjay Kumar; Singh, V. B.

2018-05-01

A new type of nanocomposite, Ni-Al4C3 was prepared using Al4C3 as reinforcement by cathodic co-deposition at different current densities (1.0 to 5.0 A dm‑2) from a nickel acetate-N-methyl formamide (non-aqueous) bath. Influence of current density and incorporation of Al4C3 particles in nickel matrix on the structure and properties of the composite coatings was investigated. Surface morphology and composition of the deposits were determined by SEM and EDAX. Crystallographic structure and orientation of the electrodeposited Ni-Al4C3 composite were studied by x-ray diffraction. Compared to nickel metal, these nanocomposites exhibited finer grains, higher microhardness, improved corrosion resistance and enhanced soft magnetic properties. Composite deposited at higher current densities (>2 A dm‑2) shows mild texturing along (200) plane. The effect of heat treatment on the microstructure, texture and microhardness of the nanocomposites was also investigated.

Preparation and characteristics of epoxy/clay/B4C nanocomposite at high concentration of boron carbide for neutron shielding application

NASA Astrophysics Data System (ADS)

Kiani, Mohammad Amin; Ahmadi, Seyed Javad; Outokesh, Mohammad; Adeli, Ruhollah; Mohammadi, Aghil

2017-12-01

In this research, the characteristics of the prepared samples in epoxy matrix by means of X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), as well as scanning electron microscope (SEM) are evaluated. Meanwhile, the obtained mechanical properties of the specimen are investigated. Thermogravimetric analysis (TGA) is also employed to evaluate the thermal degradation of manufactured nanocomposites. The thermal neutron absorption properties of nanocomposites containing 3 wt% of montmorillonite nanoclay (closite30B) have been studied experimentally, using an Am-Be point source. Mechanical tests reveal that the higher B4C concentrations, the more tensile strengths, but lower Young's modulus in all samples under consideration. TGA analysis also shows that thermal stability of the nanocomposite, increases in presence of B4C. Finally, neutron absorption analysis shows that increasing the B4C concentration leads to a nonlinearly build-up of neutron absorption cross section.

Optical and Thermal Behaviors of Polyamide-Layered Silicate Nanocomposites Based on 4,4'-Azodibenzoic Acid by Solution Intercalation Technique

NASA Astrophysics Data System (ADS)

Faghihi, Khalil; Shabanian, Meisam

2011-04-01

Two new samples of polyamide-montmorillonite reinforced nanocomposites based on 4,4'-azodibenzoic acid were prepared by a convenient solution intercalation technique. Polyamide (PA) 4 as a source of polymer matrix was synthesized by the direct polycondensation reaction of 4,4'-azodibenzoic acid 2 with 4,4'-diamino diphenyl sulfone 3 in the presence of triphenyl phosphate (TPP), CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP). Morphology and structure of the resulting PA-nanocomposite films 4a and 4b with 10 and 20% silicate particles were characterized by FTIR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect of clay dispersion and the interaction between clay and polymeric chains on the properties of nanocomposite films were investigated by using Uv-vis spectroscopy, thermogravimetric analysis (TGA) and water uptake measurements.

Preparation and optical properties of Au/Teflon nanocomposites.

PubMed

Goncharenko, A V; Grynko, D O; Grytsenko, K P; Lozovski, V Z

2005-11-01

Using thermal deposition technique, we have prepared Au/Teflon thin films on glass substrates. To control the film microstructure, both TEM and AFM characterization have been carried out. The visible optical transmission spectra have been measured in-situ. The peak positions and linewidths in the spectra have been identified in terms of the gold nanoparticle shape, size, and arrangement. The results obtained provide evidence for formation of both sphere-like and cylinder-like gold nanoparticles in the films. The fraction of each kind of the particles depends on whether the plasma treatment has been used. The treatment is shown to enhance the fraction of the cylinder-like particles.

Synthesis of malachite@clay nanocomposite for rapid scavenging of cationic and anionic dyes from synthetic wastewater.

PubMed

Srivastava, Varsha; Sillanpää, Mika

2017-01-01

Synthesis of malachite@clay nanocomposite was successfully carried out for the removal of cationic (Methylene Blue, MB) and anionic dyes (Congo Red, CR) from synthetic wastewater. Nanocomposite was characterized by TEM, SEM, FT-IR, EDS analysis and zeta potential. TEM analysis indicated that the particle diameter of nanocomposite was in the range of 14 to 23nm. Various important parameters viz. contact time, concentration of dyes, nanocomposite dosage, temperature and solution pH were optimized to achieve maximum adsorption capacity. In the case of MB, removal decreased from 99.82% to 93.67% while for CR, removal decreased from 88.55% to 75.69% on increasing dye concentration from 100 to 450mg/L. pH study confirmed the higher removal of CR in acidic range while MB removal was higher in alkaline range. Kinetic study revealed the applicability of pseudo-second-order model for the adsorption of both dyes. Negative values of ΔG 0 for both systems suggested the feasibility of dye removal and support for spontaneous adsorption of CR and MB on nanocomposite. Nanocomposite showed 277.77 and 238.09mg/g Langmuir adsorption capacity for MB and CR respectively. Desorption of dyes from the dye loaded nanocomposite was easily carried out with acetone. The results indicate that the prepared malachite@clay nanocomposite is an efficient adsorbent with high adsorption capacity for the aforementioned dyes. Copyright © 2016. Published by Elsevier B.V.

Ultrasound assisted synthesis of WO3-ZnO nanocomposites for brilliant blue dye degradation.

PubMed

Hunge, Y M; Yadav, A A; Mathe, V L

2018-07-01

The present work deals with the preparation of WO 3 and WO 3 -ZnO nanocomposites in presence of ultrasonic irradiation, and its use in the sonocatalytic degradation of brilliant blue dye. WO 3 -ZnO nanocomposite is prepared using one step in-situ ultrasound assisted method. The successfully prepared WO 3 and WO 3 -ZnO nanocomposites were characterized using different characterization techniques such as XRD, Raman, BET, FE-SEM and EDS. The XRD pattern reveals that the formation of monoclinic and hexagonal crystal structures of WO 3 and ZnO respectively. BET study shows that WO 3 -ZnO nanocomposite have maximum surface area than that of the WO 3 . EDS study confirms the formation of WO 3 -ZnO nanocomposites. Further the use of the prepared WO 3 and WO 3 -ZnO nanocomposites as a sonocatalyst for the degradation of brilliant blue dye. The rate constant (k) was evaluated as a function of the initial concentration of brilliant blue dye. It is found that WO 3 -ZnO nanocomposites exhibits maximum sonocatalytic activity as compared to WO 3 photocatalyst. Copyright © 2018 Elsevier B.V. All rights reserved.

Microorganism Nutrition Processes as a General Route for the Preparation of Bionic Nanocomposites Based on Intractable Polymers.

PubMed

Valentini, L; Bon, S Bittolo; Pugno, N M

2016-08-31

In this paper the fermentation process activated by living microorganisms of the baker's yeast is proposed as a facile assembly method of hybrid nanoparticles at liquid interface. Water dispersion of commercial baker's yeast extract used for bread production, graphene nanoplatelets (GNPs), and carbon nanotubes (CNTs) were added to oil/water interface; when the yeast is activated by adding sugar, the byproduct carbon dioxide bubbles migrate from the water phase to the oil/water interface generating a floating nanostructured film at liquid interface where it is trapped. Starting from this simple method, we propose a general approach for the stabilization of intractable poly(etheretherketone) polymeric particles with GNPs and CNTs at immiscible liquid interface. This process allowed the formation of sintered porous composites with improved mechanical properties. The porous structure of the composites gave rise to a low thermal conductivity making them good candidates for thermal insulating applications. Liquid absorption by these porous composites has been also reported. We believe that this new approach may have applications in the large scale fabrication of nanomaterials and is particularly suited for the preparation of nanocomposites starting from polymers that are intractable by solvent casting.

Preparation, characterization and photocatalytic activity of visible-light-driven plasmonic Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposites

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

Li, Xiaojuan, E-mail: lixiaojuan@fzu.edu.cn; Tang, Duanlian; Tang, Fan

2014-08-15

Highlights: • A plasmonic Ag/AgBr/ZnFe{sub 2}O{sub 4} photocatalyst has been successfully synthesized. • Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposites exhibit high visible light photocatalytic activity. • Ag/AgBr/ZnFe{sub 2}O{sub 4} photocatalyst is stable and magnetically separable. - Abstract: A visible-light-driven plasmonic Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposite has been successfully synthesized via a deposition–precipitation and photoreduction through a novel one-pot process. X-ray diffraction spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy were employed to investigate the crystal structure, chemical composition, morphology, and optical properties of the as-prepared nanocomposites. The photocatalytic activities of the nanocomposites were evaluated by photodegradationmore » of Rhodamine B (RhB) and phenol under visible light. The results demonstrated that the obtained Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposites exhibited higher photocatalytic activity as compared to pure ZnFe{sub 2}O{sub 4}. In addition, the sample photoreduced for 20 min and calcined at 500 °C achieved the highest photocatalytic activity. Furthermore, the Ag/AgBr/ZnFe{sub 2}O{sub 4} nanocomposite has high stability under visible light irradiation and could be conveniently separated by using an external magnetic field.« less

Facile hydrothermal growth graphene/ZnO nanocomposite for development of enhanced biosensor.

PubMed

Low, Sze Shin; Tan, Michelle T T; Loh, Hwei-San; Khiew, Poi Sim; Chiu, Wee Siong

2016-01-15

Graphene/zinc oxide nanocomposite was synthesised via a facile, green and efficient approach consisted of novel liquid phase exfoliation and solvothermal growth for sensing application. Highly pristine graphene was synthesised through mild sonication treatment of graphite in a mixture of ethanol and water at an optimum ratio. The X-ray diffractometry (XRD) affirmed the hydrothermal growth of pure zinc oxide nanoparticles from zinc nitrate hexahydrate precursor. The as-prepared graphene/zinc oxide (G/ZnO) nanocomposite was characterised comprehensively to evaluate its morphology, crystallinity, composition and purity. All results clearly indicate that zinc oxide particles were homogenously distributed on graphene sheets, without any severe aggregation. The electrochemical performance of graphene/zinc oxide nanocomposite-modified screen-printed carbon electrode (SPCE) was evaluated using cyclic voltammetry (CV) and amperometry analysis. The resulting electrode exhibited excellent electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2) in a linear range of 1-15 mM with a correlation coefficient of 0.9977. The sensitivity of the graphene/zinc oxide nanocomposite-modified hydrogen peroxide sensor was 3.2580 μAmM(-1) with a limit of detection of 7.4357 μM. An electrochemical DNA sensor platform was then fabricated for the detection of Avian Influenza H5 gene based on graphene/zinc oxide nanocomposite. The results obtained from amperometry study indicate that the graphene/zinc oxide nanocomposite-enhanced electrochemical DNA biosensor is significantly more sensitive (P < 0.05) and efficient than the conventional agarose gel electrophoresis. Copyright © 2015 Elsevier B.V. All rights reserved.

A review on preparation of silver nano-particles

NASA Astrophysics Data System (ADS)

Haider, Adawiya J.; Haider, Mohammad J.; Mehde, Mohammad S.

2018-05-01

The term "nano particle" (NP) refers to particle diameter in nanometers in size. Nanoparticles contain a small number of constituent atoms or molecules that differ from the properties inherent in their bulk counterparts, found in various forms such as spherical, triangular, cubic, pentagonal, rod-shaped, shells, elliptical and so on. In this chapter, it has been presented the theoretical concepts of the preparation of AgNPS as powders and collide nanoparticles, techniques of preparation with their characterization (morphology, sign charge and potential value, particle distribution ….etc.). Also, included unique properties of AgNPS that are different from those of their bulk materials like: High surface area to volume ratio effects Quantization of electronic and vibration properties.

Cellulose nanofibrils (CNF) filled boron nitride (BN) nanocomposites

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

Sulaiman, Hanisah Syed; Hua, Chia Chin; Zakaria, Sarani

In this study, nanocomposite using cellulose nanofibrils filled with different percentage of boron nitride (CNF-BN) were prepared. The objective of this research is to study the effect of different percentage of BN to the thermal conductivity of the nanocomposite produced. The CNF-BN nanocomposite were characterization by FT-IR, SEM and thermal conductivity. The FT-IR analysis of the CNF-BN nanocomposite shows all the characteristic peaks of cellulose and BN present in all samples. The dispersion of BN in CNF were seen through SEM analysis. The effect of different loading percentage of BN to the thermal conductivity of the nanocomposite were also investigated.

Fabrication and magnetic properties of granular Co/porous InP nanocomposite materials

PubMed Central

2011-01-01

A novel Co/InP magnetic semiconductor nanocomposite was fabricated by electrodeposition magnetic Co nanoparticles into n-type porous InP templates in ethanol solution of cobalt chloride. The content or particle size of Co particles embedded in porous InP increased with increasing deposition time. Co particles had uniform distribution over pore sidewall surface of InP template, which was different from that of ceramic template and may open up new branch of fabrication of nanocomposites. The magnetism of such Co/InP nanocomposites can be gradually tuned from diamagnetism to ferromagnetism by increasing the deposition time of Co. Magnetic anisotropy of this Co/InP nanocomposite with magnetization easy axis along the axis of InP square channel was well realized by the competition between shape anisotropy and magnetocrystalline anisotropy. Such Co/InP nanocomposites with adjustable magnetism may have potential applications in future in the field of spin electronics. PACS: 61.46. +w · 72.80.Tm · 81.05.Rm · 75.75. +a · 82.45.Aa PMID:21711809

Fabrication and magnetic properties of granular Co/porous InP nanocomposite materials.

PubMed

Zhou, Tao; Cheng, Dandan; Zheng, Maojun; Ma, Li; Shen, Wenzhong

2011-03-31

A novel Co/InP magnetic semiconductor nanocomposite was fabricated by electrodeposition magnetic Co nanoparticles into n-type porous InP templates in ethanol solution of cobalt chloride. The content or particle size of Co particles embedded in porous InP increased with increasing deposition time. Co particles had uniform distribution over pore sidewall surface of InP template, which was different from that of ceramic template and may open up new branch of fabrication of nanocomposites. The magnetism of such Co/InP nanocomposites can be gradually tuned from diamagnetism to ferromagnetism by increasing the deposition time of Co. Magnetic anisotropy of this Co/InP nanocomposite with magnetization easy axis along the axis of InP square channel was well realized by the competition between shape anisotropy and magnetocrystalline anisotropy. Such Co/InP nanocomposites with adjustable magnetism may have potential applications in future in the field of spin electronics.PACS: 61.46. +w · 72.80.Tm · 81.05.Rm · 75.75. +a · 82.45.Aa.

Photocatalytic activity of binary metal oxide nanocomposites of CeO2/CdO nanospheres: Investigation of optical and antimicrobial activity.

PubMed

Magdalane, C Maria; Kaviyarasu, K; Vijaya, J Judith; Siddhardha, Busi; Jeyaraj, B

2016-10-01

We report the synthesis of high quality CeO2-CdO binary metal oxide nanocomposites were synthesized by a simple chemical precipitation and hydrothermal method. Cerium nitrate and cadmium nitrate were used as precursors. Composition, structure and morphology of the nanocomposites were analyzed by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). XRD pattern proves that the final product has cubic phase and the particle size diameter of the nanocomposites are 27nm, XRD results also indicated that the crystalline properties of the nanocomposite were improved without affecting the parent lattice, FESEM analysis indicates that the product is composed of spherical particles in clusters. The morphological and optical properties of CeO2-CdO nanosamples were characterized by HRTEM and DRS spectroscopy. The IR results showed high purity of products and indicated that the nanocomposites are made up of CeO2 and CdO bonds. Absorption spectra exhibited an upward shift in characteristic peaks caused by the addition of transition metal oxide, suggesting that crystallinity of both the metal oxide is improved due to specific doping level. TGA plots further confirmed the purity and stability of nanomaterials prepared. Hence the nanocomposite has cubic crystal lattice and form a homogeneous solid structure. From the result, Cd(2+) ions are embedded in the cubic crystal lattice of ceria. The growth rate increases which are ascribed to the cationic doping with a lower valence cation. Ce-Cd binary metal oxide nanocomposites showed antibacterial activity, it showed the better growth inhibition towards p.aeruginosa. Exploit of photodegradation and photocatalytic activity of large scale synthesis of CeO2-CdO binary metal oxide nanocomposites was reported. Copyright © 2016 Elsevier B.V. All rights reserved.

Physical, mechanical and neutron shielding properties of h-BN/Gd2O3/HDPE ternary nanocomposites

NASA Astrophysics Data System (ADS)

İrim, Ş. Gözde; Wis, Abdulmounem Alchekh; Keskin, M. Aker; Baykara, Oktay; Ozkoc, Guralp; Avcı, Ahmet; Doğru, Mahmut; Karakoç, Mesut

2018-03-01

In order to prepare an effective neutron shielding material, not only neutron but also gamma absorption must be taken into account. In this research, a polymer nanocomposite based novel type of multifunctional neutron shielding material is designed and fabricated. For this purpose, high density polyethylene (HDPE) was compounded with different amounts of hexagonal boron nitride (h-BN) and Gd2O3 nanoparticles having average particle size of 100 nm using melt-compounding technique. The mechanical, thermal and morphological properties of nanocomposites were investigated. As filler content increased, the absorption of both neutron and gamma fluxes increased despite fluctuating neutron absorption curves. Adding h-BN and Gd2O3 nano particles had a significant influence on both neutron and gamma attenuation properties (Σ, cm-1 and μ/ρ, cm-2/g) of ternary shields and they show an enhancement of 200-280%, 14-52% for neutron and gamma radiations, respectively, in shielding performance.

Can nature's design be improved upon? High strength, transparent nacre-like nanocomposites with double network of sacrificial cross links.

PubMed

Podsiadlo, Paul; Kaushik, Amit K; Shim, Bong Sup; Agarwal, Ashish; Tang, Zhiyong; Waas, Anthony M; Arruda, Ellen M; Kotov, Nicholas A

2008-11-20

The preparation of a high-strength and highly transparent nacre-like nanocomposite via layer-by-layer assembly technique from poly(vinyl alcohol) (PVA) and Na+-montmorillonite clay nanosheets is reported in this article. We show that a high density of weak bonding interactions between the polymer and the clay particles: hydrogen, dipole-induced dipole, and van der Waals undergoing break-reform deformations, can lead to high strength nanocomposites: sigmaUTS approximately 150 MPa and E' approximately 13 GPa. Further introduction of ionic bonds into the polymeric matrix creates a double network of sacrificial bonds which dramatically increases the mechanical properties: sigmaUTS approximately 320 MPa and E' approximately 60 GPa.

Preparation of Tween 80-Zn/Al-Levodopa-Layered Double Hydroxides Nanocomposite for Drug Delivery System

PubMed Central

Kura, Aminu Umar; Hussein-Al-Ali, Samer Hasan; Hussein, Mohd Zobir; Fakurazi, Sharida

2014-01-01

We incorporated anti-Parkinsonian drug, levodopa (dopa), in Zn/Al-LDH by coprecipitation method to form dopa-LDH nanocomposite. Further coating of Tween-80 on the external surfaces of dopa-LDH nanocomposite was achieved through the oxygen of C=O group of Tween-80 with the layer of dopa-LDH nanocomposite. The final product is called Tween-dopa-LDH nanocomposite. The X-ray diffraction indicates that the Tween-dopa-LDH nanocomposite was formed by aggregation structure. From the TGA data, the Tween-80 loading on the surface of LDH and dopa-LDH was 8.6 and 7.4%, respectively. The effect of coating process on the dopa release from Tween-dopa-LDH nanocomposite was also studied. The release from Tween-dopa-LDH nanocomposite shows slower release compared to the release of the drug from dopa-LDH nanocomposite as done previously in our study, presumably due to the retarding shielding effect. The cell viability study using PC12 showed improved viability with Tween-80 coating on dopa-LDH nanocomposite as studied by mitochondrial dehydrogenase activity (MTT assay). PMID:24782658

Preparation and Mechanical Properties of Graphene Oxide: Cement Nanocomposites

PubMed Central

Babak, Fakhim; Abolfazl, Hassani; Alimorad, Rashidi; Parviz, Ghodousi

2014-01-01

We investigate the performance of graphene oxide (GO) in improving mechanical properties of cement composites. A polycarboxylate superplasticizer was used to improve the dispersion of GO flakes in the cement. The mechanical strength of graphene-cement nanocomposites containing 0.1–2 wt% GO and 0.5 wt% superplasticizer was measured and compared with that of cement prepared without GO. We found that the tensile strength of the cement mortar increased with GO content, reaching 1.5%, a 48% increase in tensile strength. Ultra high-resolution field emission scanning electron microscopy (FE-SEM) used to observe the fracture surface of samples containing 1.5 wt% GO indicated that the nano-GO flakes were well dispersed in the matrix, and no aggregates were observed. FE-SEM observation also revealed good bonding between the GO surfaces and the surrounding cement matrix. In addition, XRD diffraction data showed growth of the calcium silicate hydrates (C-S-H) gels in GO cement mortar compared with the normal cement mortar. PMID:24574878

Preparation of Cu₂O-Reduced Graphene Nanocomposite Modified Electrodes towards Ultrasensitive Dopamine Detection.

PubMed

He, Quanguo; Liu, Jun; Liu, Xiaopeng; Li, Guangli; Deng, Peihong; Liang, Jing

2018-01-12

Cu₂O-reduced graphene oxide nanocomposite (Cu₂O-RGO) was used to modify glassy carbon electrodes (GCE), and applied for the determination of dopamine (DA). The microstructure of Cu₂O-RGO nanocomposite material was characterized by scanning electron microscope. Then the electrochemical reduction condition for preparing Cu₂O-RGO/GCE and experimental conditions for determining DA were further optimized. The electrochemical behaviors of DA on the bare electrode, RGO- and Cu₂O-RGO-modified electrodes were also investigated using cyclic voltammetry in phosphate-buffered saline solution (PBS, pH 3.5). The results show that the oxidation peaks of ascorbic acid (AA), dopamine (DA), and uric acid (UA) could be well separated and the peak-to-peak separations are 204 mV (AA-DA) and 144 mV (DA-UA), respectively. Moreover, the linear response ranges for the determination of 1 × 10 -8 mol/L~1 × 10 -6 mol/L and 1 × 10 -6 mol/L~8 × 10 -5 mol/L with the detection limit 6.0 × 10 -9 mol/L (S/N = 3). The proposed Cu₂O-RGO/GCE was further applied to the determination of DA in dopamine hydrochloride injections with satisfactory results.

Novel Flaxseed Gum Nanocomposites Are Slow Release Iron Supplements.

PubMed

Liang, Shan; Huang, Yu; Shim, Youn Young; Ma, Xiang; Reaney, Martin J T; Wang, Yong

2018-05-23

Nanocomposites, based on iron salts and soluble flaxseed gum (FG), were prepared as potential treatments of iron deficiency anemia (IDA). FG was extracted, characterized, and formulated into iron-loading nanocomposites via ion-exchange against FeCl 3 , Fe 2 (SO 4 ) 3 , FeCl 2 , and FeSO 4 ·7H 2 O. FG-iron nanocomposites preparation condition was optimized, and physicochemical properties of the nanocomposites were investigated. In vitro release kinetics of iron in simulated gastric fluid (SGF) was also evaluated. FG heteropolysaccharide, consisting of rhamnose (33.73%), arabinose (24.35%), xylose (14.23%), glucose (4.54%), and galactose (23.15%) monosaccharides, linked together via varieties of glycosidic bonds, was a good recipient for both ferric and ferrous irons under screened conditions (i.e., 80 °C, 2 h, I/G = 1:2). Iron loaded contents in the nanocomposites prepared from FG-FeCl 3 , FG-Fe 2 (SO 4 ) 3 , FG-FeCl 2 , and FG-FeSO 4 ·7H 2 O were 25.51%, 10.36%, 5.83%, and 22.83%, respectively. Iron in these nanocomposites was mostly in a bound state, especially in FG-FeCl 3 , due to chelation forming bonds between iron and polysaccharide hydroxyl or carboxyl groups and formed stable polysaccharide-iron crystal network structures. Free iron ions were effectively removed by ethanol treatments. Because of chelation, the nanocomposites delayed iron release in SGF and the release kinetics were consistent with Korsmeyer-Peppas model. This indicates that such complexes might reduce side effects of free iron in human stomach. Altogether, this study indicates that these synthetic FG-iron nanocomposites might be developed as novel iron supplements for iron deficiency, in which FG-FeCl 3 is considered as the best option.

Chitosan-based nanocomposites for de-nitrification of water

NASA Astrophysics Data System (ADS)

Masheane, Monaheng L.; Nthunya, Lebea N.; Malinga, Soraya P.; Nxumalo, Edward N.; Mhlanga, Sabelo D.

2017-08-01

Novel chitosan (CTs) nanocomposite beads containing alumina (Al2O3, denoted as Al in the nanocomposites) and functionalized multiwalled carbon nanotubes (f-MWCNTs) (CTsAl/f-MWCNTs) were prepared using an environmentally benign phase inversion method and subsequently used for the removal of nitrates (NO3-) in water. The ellipsoidal beads with an average size of 3 mm were readily formed at room temperature and contained a small amount of Al (20 wt%) and f-MWCNTs (5%). The beads were found to adsorb nitrates effectively over a wide range of pH (pH 2 - pH 6) and showed maximum nitrates removal of 96.8% from a 50 mg/L nitrate water solution. Pure CTs beads on the other hand removed only 23% at pH 4. Kinetic studies suggested that the particle diffusion was rate controlling step for the adsorption of nitrates on CTsAl/f-MWCNT nanocomposite beads. Langmuir-Freundlich isotherms revealed that the adsorption of nitrates was on the heterogeneous surface of CTsAl/f-MWCNT beads. The Dubinin-Radushkevich (D-R) isotherm further revealed that the adsorption of nitrates was by electrostatic interaction. Thermodynamic studies suggested that the adsorption was spontaneous and exothermic. More than 70% recovery was achieved for 5 cycles of desorption-degeneration studies. Al and f-MWCNTs have shown to improve swelling and solubility of CTs.

Preparation of mesoporous carbon nitride structure by the dealloying of Ni/a-CN nanocomposite films

NASA Astrophysics Data System (ADS)

Zhou, Han; Shen, Yongqing; Huang, Jie; Liao, Bin; Wu, Xianying; Zhang, Xu

2018-05-01

The preparation of mesoporous carbon nitride (p-CN) structure by the selective dealloying process of Ni/a-CN nanocomposite films is investigated. The composition and structure of the Ni/a-CN nanocomposite films and porous carbon nitride (p-CN) films are determined by scan electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Phase separated structure including nickel carbide phase and the surrounding amorphous carbon nitride (a-CN) matrix are detected for the as-deposited films. Though the bulk diffusion is introduced in the film during the annealing process, the grain sizes for the post-annealed films are around 10 nm and change little comparing with the ones of the as-deposited films, which is associated with the thermostability of the CN surrounding in the film. The p-CN skeleton with its pore size around 12.5 nm is formed by etching the post-annealed films, indicative of the stability of the phase separated structure during the annealing process.

Melt rheological properties of nucleated PET/MWCNT nanocomposites

NASA Astrophysics Data System (ADS)

Gaonkar, Amita; Murudkar, Vrishali; Deshpande, V. D.

2018-05-01

This work investigates the effect of precipitated Polyethylene Terephthalate (p-PET) and loading of Multiwalled carbon nanotubes (MWCNT) on morphology and rheology of Polyethylene Terephthalate (PET)/MWCNT nanocomposites. As received PET and Self-Nucleated PET (Nuc-PET) nanocomposites with different loadings of multi-walled carbon nanotubes (MWCNT) were prepared by melt mixing technique. Synthesized reorganized PET crystallizes rapidly from the melt and it is used in small quantities as a self-nucleating agent to make Nuc-PET. In the present study, Rheological properties of nanocomposites are obtained and results show with increase in MWCNT loading complex viscosity of nanocomposites increases. Nonterminal solid like rheological behavior of PET nanocomposites were observed at low frequencies, which indicates the formation of the network like structures of MWCNT in nanocomposites. Morphological and rheological properties of self-nucleated PET nanocomposites improved significantly may be due to self-nucleating agent p-PET. Morphological properties were studied by Scanning Electron Microscopy (SEM). SEM shows better dispersion of MWCNT in Nuc-PET nanocomposites.

Simple preparation of magnetic field-responsive structural colored Janus particles.

PubMed

Teshima, Midori; Seki, Takahiro; Takeoka, Yukikazu

2018-03-08

We established a simple method for preparing Janus particles displaying different structural colors using submicron-sized fine silica particles and magnetic nanoparticles composed of Fe 3 O 4 . A w/o emulsion is prepared by vortex-stirring a mixed aqueous solution of suspended fine silica particles and magnetic nanoparticles and of hexadecane containing an emulsifier. Subsequent drying of the emulsion on a hot plate using a magnetic stirrer provides a polydisperse particle aggregate displaying two different structural colors according to the ratio of the amount of fine silica particles to the amount of magnetic nanoparticles. This polydisperse particle aggregate can be converted into monodisperse particles simply by using a sieve made of stainless steel. In the presence of a magnet, the monodisperse Janus particles can change their orientation and can switch between two different structural colors.

Synthesis and characterization of maleimide-functionalized polystyrene-SiO2/TiO2 hybrid nanocomposites by sol-gel process

NASA Astrophysics Data System (ADS)

Ramesh, Sivalingam; Sivasamy, Arumugam; Kim, Joo-Hyung

2012-06-01

Maleimide-functionalized polystyrene (PSMA-SiO2/TiO2) hybrid nanocomposites were prepared by sol-gel reaction starting from tratraethoxysilane (TEOS) and titanium isopropoxide in the solution of polystyrene maleimide in 1,4-dioxane. The hybrid films were obtained by the hydrolysis and polycondensation of TEOS and titanium isopropoxide in maleimide-functionalized polystyrene solution followed by the Michael addition reaction. The transparency of polymer (PSMA-SiO2/TiO2) hybrid was prepared from polystyrene titanium isopropoxide using the γ-aminopropyltriethoxy silane as crosslinking agent by in situ sol-gel process via covalent bonding between the organic-inorganic hybrid nanocomposites. The maleimide-functionalized polystyrene was synthesized by Friedel-Crafts reaction from N-choloromethyl maleimide. The FTIR spectroscopy data conformed the occurrence of Michael addition reaction between the pendant maleimide moieties of the styrene and γ-aminopropyltriethoxysilane. The chemical structure and morphology of PSMA-SiO2/TiO2 hybrid nanocomposites were characterized by FTIR, nuclear magnetic resonance (NMR), 13 C NMR, SEM, XRD, and TEM analyses. The results also indicate that the inorganic particles are much smaller in the ternary systems than in the binary systems; the shape of the inorganic particles and compatibility for maleimide-functionalized polystrene and inorganic moieties are varied with the ratio of the inorganic moieties in the hybrids. Furthermore, TGA and DSC results indicate that the thermal stability of maleimide-functionalized polystyrene was enhanced through the incorporation of the inorganic moieties in the hybrid materials.

Synthesis of PbS/TiO2 nanocomposite materials using the sol-gel process via the incorporation of lead thiolates

NASA Astrophysics Data System (ADS)

Patel, Khushikumari

PbS/TiO2 nanocomposites were prepared by two methods using the sol-gel process: a one step process and a multi-step process. The incorporation of 3-mercaptopropionic acid, followed by the addition of Pb2+ generated covalently incorporated lead thiolate precursors which can then be converted to PbS/TiO2 nanocomposites by controlled thermal decomposition. Various ratios of bifunctional linker to matrix were used to monitor the incorporation of functional groups of the ceramic matrix, and the sol-gel process was used to produce a high yield ceramic materials. This allows solutions to chemically bind and form solid state ceramics, while allowing complex compounds to combine with a high degree of homogeneity. 3-mercaptoproprionic acid, was added to the titania gel, and as a source of sulfur component to bind to the titania. PbS/TiO2 nanocomposites were studied using FTIR spectroscopy. The covalent bonding between PbS and the titania ceramics was also confirmed with the signal intensity in the infrared spectra. The success of the covalent bond between the thiolate and ceramics led to possibility of nanocomposites. X-ray diffraction was used analyze the structure of the nanocomposites X-ray diffraction results showed lead sulfide nanocrystals in the ceramic matrix as well as the size of the particles. The presence of crystalline PbS and particle size was determined using powder X-ray diffraction.

Scanning transmission electron microscopy analysis of Ge(O)/(graphitic carbon nitride) nanocomposite powder

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

Kawasaki, Masahiro; Sompetch, Kanganit; Sarakonsri, Thapanee, E-mail: tsarakonsri@gmail.com

2015-12-15

Analytical electron microscopy has revealed the structure of particles that were synthesized by chemical reaction of GeO{sub 2} with NaBH{sub 4} in the basic solution including graphitic carbon nitride (g-C{sub 3}N{sub 4}) powders. The g-C{sub 3}N{sub 4} was arranged by recrystallization of melamine at 600 °C under N{sub 2} gas atmosphere. The samples were dried at 60 °C or 180 °C for 4 h. The g-C{sub 3}N{sub 4} was observed as lamellae of several ten nm or less in size and had an amorphous-like structure with a distorted lattice in an area as small as a few hundred pm inmore » size. The reaction product was Ge(O) particles as fine as several nm in size and composed of Ge and O atoms. Most of the particles must be of GeO{sub 2−x} with the amorphous-like structure that has also a distorted lattice in an area of a few hundred pm in size. In the sample dried at 60 °C, the particles were found to be dispersed in a wide area on the g-C{sub 3}N{sub 4} lamella. It is hard to recognize those particles in TEM images. The particles in the sample dried at 180 °C became larger and were easily observed as isolated lumps. Hence, these powders can be regarded as GeO{sub 2}/g-C{sub 3}N{sub 4} or Ge/GeO{sub 2}/g-C{sub 3}N{sub 4} nanocomposites, and expected to be applicable to anode materials for high energy Li-ion batteries due to Ge catalysis effect, accordingly. - Graphical abstract: STEM analysis of Ge(O)/(graphitic carbon nitride) nanocomposite powder. - Highlights: • Graphitic (g)-C{sub 3}N{sub 4} powder was prepared at 600 °C by recrystallization of melamine. • Ge(O) was prepared by chemical reaction in a solution including the g-C{sub 3}N{sub 4} powders. • The products can be regarded as GeO{sub 2}/g-C{sub 3}N{sub 4} or Ge/GeO{sub 2}/g-C{sub 3}N{sub 4} nanocomposites. • GeO{sub 2} was amorphous several-nm particles and g-C{sub 3}N{sub 4} was amorphous lamella of several 10 nm in size. • We expect them to be applicable for high energy Li-ion battery anode

Preparation of spherical particles by vibrating orifice technique

NASA Astrophysics Data System (ADS)

Shibata, Shuichi; Tomizawa, Atsushi; Yoshikawa, Hidemi; Yano, Tetsuji; Yamane, Masayuki

2000-05-01

Preparation of micrometer-sized spherical particles containing Rhodamine 6G (R6G) has been investigated for the spherical cavity micro-laser. Using phenyl triethoxy silane (PTES) as a starting material, R6G-doped monodisperse spherical particles were prepared by the vibrating orifice technique. Processing consists of two major processes: (1) Hydrolysis and polymerization of PTES and (2) Droplet formation from PTES oligomers by vibrating orifice technique. A cylindrical liquid jet passing through the orifice of 10 and 20 micrometers in diameter breaks up into equal- sized droplets by mechanical vibration. Alcohol solvent of these droplets was evaporated during flying with carrier gas and subsequently solidified in ammonium water trap. For making smooth surface and god shaped particles, control of molecular weight of PTES oligomer was essential. R6G-doped hybrid spherical particles of 4 to 10 micrometers size of cavity structure were successfully obtained. The spherical particles were pumped by a second harmonic pulse of Q- switched Nd:YAG laser and laser emission peaks were observed at wavelengths which correspond to the resonance modes.

Biopolymer nanocomposite films reinforced with nanocellulose whiskers

Treesearch

Amit Saxena; Marcus Foston; Mohamad Kassaee; Thomas J. Elder; Arthur J. Ragauskas

2011-01-01

A xylan nanocomposite film with improved strength and barrier properties was prepared by a solution casting using nanocellulose whiskers as a reinforcing agent. The 13C cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) analysis of the spectral data obtained for the NCW/xylan nanocomposite films indicated the signal intensity originating...

METHOD FOR PREPARATION OF UO$sub 2$ PARTICLES

DOEpatents

Johnson, J.R.; Taylor, A.J.

1959-09-22

A method is described for the preparation of highdensity UO/sub 2/ particles within the size range of 40 to 100 microns. In accordance with the invention UO/sub 2/ particles are autoclaved with an aqueous solution of uranyl ions. The resulting crystals are reduced to UO/sub 2/ and the UO/sub 2/ is heated to at least 1000 deg C to effect densification. The resulting UO/sub 2/ particles are screened, and oversize particles are crushed and screened to recover the particles within the desired size range.

Dielectric behaviour of montmorillonite/cyanoethylated cellulose nanocomposites.

PubMed

Madusanka, Nadeesh; Shivareddy, Sai G; Eddleston, Mark D; Hiralal, Pritesh; Oliver, Rachel A; Amaratunga, Gehan A J

2017-09-15

A dielectric nanocomposite based oncyanoethylatedcellulose (CRS) and MMT nanoclay was successfully prepared with different weight percentages (5%, 10% and 15%) of MMT. MMT nanoplatets obtained via sonication of MMT nanoclay in acetone for a prolonged period was used in the preparation of CRS-MMT nanocomposites. CRS-MMT thin films on SiO 2 /Si wafers are used to form metal-insulator-metal (MIM) type capacitors. At 1kHz CRS-MMT nanocomposites exhibited high dielectric constants (ε r ) of 71, 55 and 42 with low leakage current densities (10 -6 -10 -7 A/cm 2 ) for nanocomposites with 5%, 10% and 15% weight of MMT respectively, higher than values of pure CRS (21), Na-MMT(10). Reduction of ε r with higher MMT loading can be attributed to a network formation as evidenced via strong bonding interactions between CRS and MMT leading to a lower molecular mobility. The leakage is studied using conductive atomic force microscopy (C-AFM) indicates that leakage pathways are associated with MMT nanoplatelets embedded in the CRS polymer matrix. Copyright © 2017. Published by Elsevier Ltd.

Sulfated Titania-Silica Reinforced Nafion Nanocomposite Membranes for Proton Exchange Membrane Fuel Cells.

PubMed

Abu Sayeed, M D; Kim, Hee Jin; Gopalan, A I; Kim, Young Ho; Lee, Kwang-Pill; Choi, Sang-June

2015-09-01

Sulfated titania-silica (SO4(2-)-/TiO2-SiO2) composites were prepared by a sol-gel method with sulfate reaction and characterized by X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). The nanometric diameter and geometry of the sulfated titania-silica (STS) was investigated by transmission electron microscopy (TEM). A small amount of the STS composite in the range of 0.5-3 wt% was then added as reinforcing into the Nafion membrane by water-assisted solution casting method to prepare STS reinforced Nafion nanocomposite membranes (STS-Nafion nanocomposite membranes). The additional functional groups, sulfate groups, of the nanocomposite membrane having more surface oxygenated groups enhanced the fuel cell membrane properties. The STS-Nafion nanocomposite membranes exhibited improved water uptake compared to that of neat Nafion membranes, whereas methanol uptake values were decreased dramatically improved thermal property of the prepared nanocomposite membranes were measured by thermogravimetric analysis (TGA). Furthermore, increased ion exchange capacity values were obtained by thermoacidic pretreatment of the nanocomposite membranes.

Highly Active PdNi/RGO/Polyoxometalate Nanocomposite Electrocatalyst for Alcohol Oxidation.

PubMed

Hu, Jing; Wu, Xiaofeng; Zhang, Qingfan; Gao, Mingyan; Qiu, Haifang; Huang, Keke; Feng, Shouhua; Wang, Tingting; Yang, Ying; Liu, Zhelin; Zhao, Bo

2018-02-27

A PdNi/RGO/polyoxometalate nanocomposite has been successfully synthesized by a simple wet-chemical method. Characterizations such as transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy are employed to verify the morphology, structure, and elemental composition of the as-prepared nanocomposite. Inspired by the fast-developing fuel cells, the electrochemical catalytic performance of the nanocomposite toward methanol and ethanol oxidation in alkaline media is further tested. Notably, the nanocomposite exhibits excellent catalytic activity and long-term stability toward alcohol electrooxidation compared with the PdNi/RGO and commercial Pd/C catalyst. Furthermore, the electrochemical results reveal that the prepared nanocomposite is attractive as a promising electrocatalyst for direct alcohol fuel cells, in which the phosphotungstic acid plays a crucial role in enhancing the electrocatalytic activities of the catalyst.

One step approach towards the green synthesis of silver decorated graphene nanocomposites for the degradation of organic dyes in water

NASA Astrophysics Data System (ADS)

Karthik, Gopakumar; Harith, A.; Nazrin Thazleema, N.; Vishal, Shaji; Jayan Jitha, S.; Saritha, Appukuttan

2018-02-01

Recently the decoration of graphene with metallic nanoparticles by a one pot reduction of graphene oxide (GO) coupled with the synthesis of metallic nanoparticles has gained momentum. Graphene and GO have been proved to exhibit excellent biocompatibility and high antibacterial activity and hence a vast possibility lies in the utilization of GO as an antibacterial reinforcement in biomaterials and exploration of the antiseptic properties as well as the cytotoxicity of GO-containing composites. Moreover GO decorated with metal / metal oxide paves way towards an inevitable role in water purification. The use of graphene oxide as the nano scale substrates for the development of nanocomposites with metal oxides is a novel idea to obtain a hybrid which would exhibit both the properties of GO as a enthralling paper-shape material and the quality of single nano-sized metal particles. The heavy metal ions and pollutants are considered as a major problem in environmental contamination. Hence detection of trace level pollutant has become a hot topic in the present research scenario. Modified graphene oxide nanocomposites prepared using a green approach has the capacity of absorbing pollutant material ions in high efficiency and selectivity. The green synthesized nanocomposites were characterized using FTIR and UV spectroscopy and the consequence of pH and concentration on the preparation of the nanocomposites was evaluated. The efficiency of these nanocomposites towards degradation of organic dyes like methylene blue has been evaluated.

Synthesis and characterization of fluorapatite-titania (FAp-TiO 2) nanocomposite via mechanochemical process

NASA Astrophysics Data System (ADS)

Ebrahimi-Kahrizsangi, Reza; Nasiri-Tabrizi, Bahman; Chami, Akbar

2010-09-01

In this paper, synthesis of bionanocomposite of fluorapatite-titania (FAp-TiO 2) was studied by using one step mechanochemical process. Characterization of the products was accomplished by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. Based on XRD patterns and FT-IR spectroscopy, correlation between the structural features of the nanostructured FAp-TiO 2 and the process conditions was discussed. Variations in crystallite size, lattice strain, and volume fraction of grain boundary were investigated during milling and the following heat treatment. Crystallization of the nanocomposite occurred after thermal treatment at 650 °C. Morphological features of powders were influenced by the milling time. The resulting FAp-20 wt.%TiO 2 nanocomposite powder exhibited an average particle size of 15 nm after 20 h of milling. The results show that the one step mechanosynthesis technique is an effective route to prepare FAp-based nanocomposites with excellent morphological and structural features.

Self-assembly of mesoscopically ordered chromatic polydiacetylene/silica nanocomposites

NASA Technical Reports Server (NTRS)

Lu, Y.; Yang, Y.; Sellinger, A.; Lu, M.; Huang, J.; Fan, H.; Haddad, R.; Lopez, G.; Burns, A. R.; Sasaki, D. Y.;

Synthesis and Performance Evaluation of Pulse Electrodeposited Ni-AlN Nanocomposite Coatings

PubMed Central

Ali, Kamran; Narayana, Sivaprasad; Okonkwo, Paul C.; Yusuf, Moinuddin M.; Alashraf, Abdullah

2018-01-01

This research work presents the microscopic analysis of pulse electrodeposited Ni-AlN nanocomposite coatings using SEM and AFM techniques and their performance evaluation (mechanical and electrochemical) by employing nanoindentation and electrochemical methods. The Ni-AlN nanocomposite coatings were developed by pulse electrodeposition. The nickel matrix was reinforced with various amounts of AlN nanoparticles (3, 6, and 9 g/L) to develop Ni-AlN nanocomposite coatings. The effect of reinforcement concentration on structure, surface morphology, and mechanical and anticorrosion properties was studied. SEM and AFM analyses indicate that Ni-AlN nanocomposite coatings have dense, homogenous, and well-defined pyramid structure containing uniformly distributed AlN particles. A decent improvement in the corrosion protection performance is also observed by the addition of AlN particles to the nickel matrix. Corrosion current was reduced from 2.15 to 1.29 μA cm−2 by increasing the AlN particles concentration from 3 to 9 g/L. It has been observed that the properties of Ni-AlN nanocomposite coating are sensitive to the concentration of AlN nanoparticles used as reinforcement. PMID:29619143

Transparent bulk-size nanocomposites with high inorganic loading

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

Chen, Shi; Gaume, Romain, E-mail: gaume@ucf.edu; Department of Materials Science and Engineering, University of Central Florida, Orlando, Florida 32816

2015-12-14

With relatively high nanoparticle loading in polymer matrices, hybrid nanocomposites made by colloidal dispersion routes suffer from severe inhomogeneous agglomeration, a phenomenon that deteriorates light transmission even when the refractive indices of the inorganic and organic phases are closely matched. The dispersion of particles in a matrix is of paramount importance to obtain composites of high optical quality. Here, we describe an innovative, yet straightforward method to fabricate monolithic transparent hybrid nanocomposites with very high particle loading and high refractive index mismatch tolerance between the inorganic and organic constituents. We demonstrate 77% transmission at 800 nm in a 2 mm-thick acrylate polymermore » nanocomposite containing 61 vol. % CaF{sub 2} nanoparticles. Modeling shows that similar performance could easily be obtained with various inorganic phases relevant to a number of photonic applications.« less

Sol-gel preparation of Ag-silica nanocomposite with high electrical conductivity

NASA Astrophysics Data System (ADS)

Ma, Zhijun; Jiang, Yuwei; Xiao, Huisi; Jiang, Bofan; Zhang, Hao; Peng, Mingying; Dong, Guoping; Yu, Xiang; Yang, Jian

2018-04-01

Sol-gel derived noble-metal-silica nanocomposites are very useful in many applications. Due to relatively low price, higher conductivity, and higher chemical stability of silver (Ag) compared with copper (Cu), Ag-silica has gained much more research interest. However, it remains a significant challenge to realize high loading of Ag content in sol-gel Ag-silica composite with high structural controllability and nanoparticles' dispersity. Different from previous works by using multifunctional silicon alkoxide to anchor metal ions, here we report the synthesis of Ag-silica nanocomposite with high loading of Ag nanoparticles by employing acetonitrile bi-functionally as solvent and metal ions stabilizer. The electrical conductivity of the Ag-silica nanocomposite reached higher than 6800 S/cm. In addition, the Ag-silica nanocomposite could simultaneously possess high electrical conductivity and positive conductivity-temperature coefficient by properly controlling the loading content of Ag. Such behavior is potentially advantageous for high-temperature devices (like phosphoric acid fuel cells) and inhibiting the thermal-induced increase of devices' internal resistance. The strategy proposed here is also compatible with block-copolymer directed self-assembly of mesoporous material, spin-coating of film and electrospinning of nanofiber, making it more charming in various practical applications.

Photocatalytic growth of Ag nanocrystals on hydrothermally synthesized multiphasic TiO2/reduced graphene oxide (rGO) nanocomposites and their SERS performance

NASA Astrophysics Data System (ADS)

Guo, Tian-Long; Li, Ji-Guang; Sun, Xudong; Sakka, Yoshio

2017-11-01

TiO2/reduced graphene oxide (rGO) nanocomposites were prepared via a facile one-step hydrothermal method using TiCl3 as the TiO2 precursor. Cetyltrimethyl ammonium bromide (CTAB) was introduced as a stabilizer for GO in solution. The effects of GO content, Ti3+ concentration and urea additive on phase constituent and morphology of the TiO2 crystallites in the nanocomposites were systematically investigated. UV-vis absorption ability of the as-made composites was further tested and discussed. Ag nanocrystals (NCs) were photocatalytically grown on the surfaces of biphasic (anatase + brookite) and triphasic (anatase + brookite + rutile) TiO2/rGO nanocomposites to evaluate their surface-enhanced Raman scattering (SERS) performances. Morphology evolution of the Ag NCs in response to different photocatalytic ability of the TiO2/rGO nanocomposite was also investigated in detail. The nanocomposite with triphasic TiO2 of proper phase constituents was confirmed to favor the growth of Ag particles of two distinctly different sizes and to produce SERS substrates of substantially better performance.

Nanocomposites of polymer and inorganic nanoparticles for optical and magnetic applications

PubMed Central

Li, Shanghua; Meng Lin, Meng; Toprak, Muhammet S.; Kim, Do Kyung; Muhammed, Mamoun

2010-01-01

This article provides an up-to-date review on nanocomposites composed of inorganic nanoparticles and the polymer matrix for optical and magnetic applications. Optical or magnetic characteristics can change upon the decrease of particle sizes to very small dimensions, which are, in general, of major interest in the area of nanocomposite materials. The use of inorganic nanoparticles into the polymer matrix can provide high-performance novel materials that find applications in many industrial fields. With this respect, frequently considered features are optical properties such as light absorption (UV and color), and the extent of light scattering or, in the case of metal particles, photoluminescence, dichroism, and so on, and magnetic properties such as superparamagnetism, electromagnetic wave absorption, and electromagnetic interference shielding. A general introduction, definition, and historical development of polymer–inorganic nanocomposites as well as a comprehensive review of synthetic techniques for polymer–inorganic nanocomposites will be given. Future possibilities for the development of nanocomposites for optical and magnetic applications are also introduced. It is expected that the use of new functional inorganic nano-fillers will lead to new polymer–inorganic nanocomposites with unique combinations of material properties. By careful selection of synthetic techniques and understanding/exploiting the unique physics of the polymeric nanocomposites in such materials, novel functional polymer–inorganic nanocomposites can be designed and fabricated for new interesting applications such as optoelectronic and magneto-optic applications. PMID:22110855

Large-Strain Transparent Magnetoactive Polymer Nanocomposites

NASA Technical Reports Server (NTRS)

Meador, Michael A.

2012-01-01

A document discusses polymer nano - composite superparamagnetic actuators that were prepared by the addition of organically modified superparamagnetic nanoparticles to the polymer matrix. The nanocomposite films exhibited large deformations under a magnetostatic field with a low loading level of 0.1 wt% in a thermoplastic polyurethane elastomer (TPU) matrix. The maximum actuation deformation of the nanocomposite films increased exponentially with increasing nanoparticle concentration. The cyclic deformation actuation of a high-loading magnetic nanocomposite film was examined in a low magnetic field, and it exhibited excellent reproducibility and controllability. Low-loading TPU nanocomposite films (0.1-2 wt%) were transparent to semitransparent in the visible wavelength range, owing to good dispersion of the magnetic nanoparticles. Magnetoactuation phenomena were also demonstrated in a high-modulus, high-temperature polyimide resin with less mechanical deformation.

Measurement of solubility and water sorption of dental nanocomposites light cured by argon laser.

PubMed

Mirsasaani, Seyed Shahabeddin; Ghomi, Farhad; Hemati, Mehran; Tavasoli, Tina

2013-03-01

Different parameters used for photoactivation process and also composition provide changes in the properties of dental composites. In the present work the effect of different power density of argon laser and filler loading on solubility (SL) and water sorption (WS) of light-cure dental nanocomposites was studied. The resin of nanocomposites was prepared by mixing bisphenol A glycol dimethacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA) with a mass ratio of 65/35. 20 wt.% and 25 wt.% of nanosilica fillers with a primary particle size of 10 nm were added to the resin. Camphorquinone (CQ) and DMAEMA were added as photoinitiator system. The nanocomposites were cured by applying the laser beam at the wavelength of 472 nm and power densities of 260 and 340 mW/cm(2) for 40 sec. Solubility and water sorption were then measured according to ISO 4049, which in our case, the maximums were 2.2% and 4.3% at 260 mW/cm(2) and 20% filler, respectively. The minimum solubility (1.2%) and water sorption (3.8%) were achieved for the composite containing 25% filler cured at 340 mW/cm(2). The results confirmed that higher power density and filler loading decreased solubility of unreacted monomers and water sorption and improved physico-mechanical properties of nanocomposites.

EPR and rheological study of hybrid interfaces in gold-clay-epoxy nanocomposites.

PubMed

Angelov, Verislav; Velichkova, Hristiana; Ivanov, Evgeni; Kotsilkova, Rumiana; Delville, Marie-Hélène; Cangiotti, Michela; Fattori, Alberto; Ottaviani, Maria Francesca

2014-11-11

With the aim to obtain new materials with special properties to be used in various industrial and biomedical applications, ternary "gold-clay-epoxy" nanocomposites and their nanodispersions were prepared using clay decorated with gold nanoparticles (AuNPs), at different gold contents. Nanocomposites structure was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Rheology and electron paramagnetic resonance (EPR) techniques were used in order to evaluate the molecular dynamics in the nanodispersions, as well as dynamics at interfaces in the nanocomposites. The percolation threshold (i.e., the filler content related to the formation of long-range connectivity of particles in the dispersed media) of the gold nanoparticles was determined to be ϕp = 0.6 wt % at a fixed clay content of 3 wt %. The flow activation energy and the relaxation time spectrum illustrated the presence of interfacial interactions in the ternary nanodispersions around and above the percolation threshold of AuNPs; these interfacial interactions suppressed the global molecular dynamics. It was found that below ϕp the free epoxy polymer chains ratio dominated over the chains attracted on the gold surfaces; thus, the rheological behavior was not significantly changed by the presence of AuNPs. While, around and above ϕp, the amount of the bonded epoxy polymer chains on the gold surface was much higher than that of the free chains; thus, a substantial increase in the flow activation energy and shift in the spectra to higher relaxation times appeared. The EPR signals of the nanocomposites depended on the gold nanoparticle contents and the preparation procedure thus providing a fingerprint of the different nanostructures. The EPR results from spin probes indicated that the main effect of the gold nanoparticles above ϕp, was to form a more homogeneous, viscous and polar clay-epoxy mixture at the nanoparticle surface. The knowledge

Lecithin and PLGA-based self-assembled nanocomposite, Lecithmer: preparation, characterization, and pharmacokinetic/pharmacodynamic evaluation.

PubMed

Varghese, Seby Elsy; Fariya, Mayur K; Rajawat, Gopal Singh; Steiniger, Frank; Fahr, Alfred; Nagarsenker, Mangal S

2016-08-01

The present study investigates the drug delivery potential of polymer lipid hybrid nanocomposites (Lecithmer®) composed of poly(D,L-lactide-co-glycolide (PLGA) and soya lecithin. Core-shell structure of Lecithmer was evident from cryo-TEM images. Daunorubicin (DNR) and lornoxicam (LNX)-incorporated Lecithmer nanocomposites were evaluated for anticancer and anti-inflammatory activity. DNR- and LNX-loaded Lecithmer had mean particle size of ∼335 and ∼282.7 nm, respectively. Lecithmer formulated with different cationic lipids resulted in lower particle size (∼120 nm) and positive zeta potential. Entrapment efficiency of DNR and LNX was 93.16 and 88.59 %, respectively. In vitro release of DNR from Lecithmer was slower compared to PLGA nanoparticles. DNR release from Lecithmer was significantly higher at pH 5.5 (80.96 %) as compared to pH 7.4 (55.95 %), providing advantage for selective tumor therapy. Similarly, sustained release of LNX (30 % in 10 h) was observed at pH 7.4. DNR in Lecithmer showed superior cytotoxicity on human erythroleukemic K562 cells. Pharmacokinetic study in Wistar rats with i.v. administered DNR-loaded Lecithmer showed higher volume of distribution, lower elimination rate constant, and longer half-life (81.68 L, 0.3535 h(-1), 1.96 h) as compared to DNR solution (57.46 L, 0.4237 h(-1), 1.635 h). Pharmacodynamic evaluation of orally administered LNX-loaded Lecithmer showed superior anti-inflammatory activity with maximum inhibition of 81.2 % vis-à-vis 53.57 % in case of LNX suspension. In light of these results, Lecithmer can be envisaged as a promising nanosystem for parenteral as well as oral drug delivery.

Phase composition and tribomechanical properties of Ti-B-C nanocomposite coatings prepared by magnetron sputtering

NASA Astrophysics Data System (ADS)

Sánchez-López, J. C.; Abad, M. D.; Justo, A.; Gago, R.; Endrino, J. L.; García-Luis, A.; Brizuela, M.

2012-09-01

Protective nanocomposite coatings based on hard ceramic phases (TiC, TiB2) combined with amorphous carbon (a-C) are of interest because of their adequate balance between mechanical and tribological performances. In this work, Ti-B-C nanocomposite coatings were prepared by co-sputtering of graphite and TiB2 targets. Varying the discharge power ratio applied to the graphite and TiB2 targets from 0 to 2, the a-C content in the coatings could be tuned from 0 to 60%, as observed by means of Raman and x-ray photoelectron spectroscopy (XPS). The microstructural characterization demonstrated a progressive decrease in crystallinity from an initial nanocrystalline (nc) TiB2-like structure to a distorted TiBxCy ternary compound with increasing C concentration. X-ray absorption near-edge structure measurements on the B K-edge helped to determine a hexagonal arrangement around the B atoms in the ternary TiBxCy phase. A fitting analysis of the C 1s XPS peak allowed us to evaluate the relative amount of a-C and TiBxCy components. A drastic change in hardness (from 52 to 13 GPa) and friction coefficient values (from 0.8 to 0.2) is noticed when moving from nc-TiB2 to TiBC/a-C nanocomposites. The fraction of a-C necessary to decrease the friction below 0.2 was found to be 45%. Raman observation of the wear tracks determined the presence of disordered sp2-bonded carbon phase associated with the diminution of the friction level.

Modifying three-dimensional scaffolds from novel nanocomposite materials using dissolvable porogen particles for use in liver tissue engineering

PubMed Central

Fuller, Barry; Seldon, Clare; Davidson, Brian; Seifalian, Alexander

2013-01-01

Background: Although hepatocytes have a remarkable regenerative power, the rapidity of acute liver failure makes liver transplantation the only definitive treatment. Attempts to incorporate engineered three-dimensional liver tissue in bioartificial liver devices or in implantable tissue constructs, to treat or bridge patients to self-recovery, were met with many challenges, amongst which is to find suitable polymeric matrices. We studied the feasibility of utilising nanocomposite polymers in three-dimensional scaffolds for hepatocytes. Materials and methods: Hepatocytes (HepG2) were seeded on a flat sheet and in three-dimensional scaffolds made of a nanocomposite polymer (Polyhedral Oligomeric Silsesquioxane [POSS]-modified polycaprolactone urea urethane) alone as well as with porogen particles, i.e. glucose, sodium bicarbonate and sodium chloride. The scaffold architecture, cell attachment and morphology were studied with scanning electron microscopy, and we assessed cell viability and functionality. Results: Cell attachment to the scaffolds was demonstrated. The scaffold made with glucose particles as porogen showed a narrower range of pore size with higher porosity and better inter-pore communications and seemed to encourage near normal cell morphology. There was a steady increase of albumin secretion throughout the experiment while the control (monolayer cell culture) showed a steep decrease after day 7. At the end of the experiment, there was no significant difference in viability and functionality between the scaffolds and the control. Conclusion: In this initial study, porogen particles were used to modify the scaffolds produced from the novel polymer. Although there was no significance against the control in functionality and viability, the demonstrable attachment on scanning electron microscopy suggest potential roles for this polymer and in particular for scaffolds made with glucose particles in liver tissue engineering. PMID:22532408

Simple synthesis of graphene nanocomposites MgO-rGO and Fe2O3-rGO for multifunctional applications

NASA Astrophysics Data System (ADS)

Abdel-Aal, Seham K.; Ionov, Andrey; Mozhchil, R. N.; Naqvi, Alim H.

2018-05-01

Hummer's method was used to prepare graphene oxide (GO) by chemical exfoliation of graphite. Simple precipitation method was used for the preparation of hybrid nanocomposites MgO-rGO and Fe2O3-rGO. A 0.3 Molar of corresponding metal nitrate solution and GO solution are used for the preparation process. XRD, FT-IR, and XPS were used to characterize the prepared nanocomposites. The reduction of GO into reduced rGO in the formed nanocomposites was confirmed. Morphological characterization showed the formation of needle-shaped nanocrystals of MgO successfully grown on graphene nanosheet with average crystallite size 8.4 nm. Hematite nanocomposite Fe2O3-rGO forms rod-shaped crystals with average crystallite size 27.5 nm. The saturation magnetization observed for Fe2O3-rGO is less than reported value for the pure Fe2O3 nanoparticles. Thermal properties of as-prepared hybrid nanocomposites MgO-rGO and Fe2O3-rGO showed thermal stability of the prepared nanocomposite over long range of temperature.

Enhanced photoinactivation of Staphylococcus aureus with nanocomposites containing plasmonic particles and hematoporphyrin.

PubMed

Khlebtsov, Boris N; Tuchina, Elena S; Khanadeev, Vitaly A; Panfilova, Elizaveta V; Petrov, Pavel O; Tuchin, Valery V; Khlebtsov, Nikolai G

2013-04-01

We fabricated composite nanoparticles consisting of a plasmonic core (gold nanorods or gold-silver nanocages) and a hematoporphyrin-doped silica shell. The dual photodynamic and photothermal activities of such nanoparticles against Staphylococcus aureus 209 P were studied and compared with the activities of reference solutions (hematoporphyrin or silica-coated plasmonic nanoparticles). Bacteria were incubated with nanocomposites or with the reference solutions for 15 min, which was followed by CW light irradiation with a few exposures of 5 to 30 min. To stimulate the photodynamic and photothermal activities of the nanocomposites, we used LEDs (405 and 625 nm) and a NIR laser (808 nm), respectively. We observed enhanced inactivation of S. aureus 209 P by nanocomposites in comparison with the reference solutions. By using fluorescence microscopy and spectroscopy, we explain the enhanced antimicrobial effect of hematoporphyrin-doped nanocomposites by their selective accumulation in the vicinity of the bacteria. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochemical detection of nitrite on poly(pyronin Y)/graphene nanocomposites modified ITO substrate

NASA Astrophysics Data System (ADS)

Şinoforoğlu, Mehmet; Dağcı, Kader; Alanyalıoğlu, Murat; Meral, Kadem

2016-06-01

The present study reports on an easy preparation of poly(pyronin Y)/graphene (poly(PyY)/graphene) nanocomposites thin films on indium tin oxide coated glass substrates (ITO). The thin films of poly(PyY)/graphene nanocomposites are prepared by a novel method consisting of three steps; (i) preparation of graphene oxide (GO) thin films on ITO by spin-coating method, (ii) self-assembly of PyY molecules from aqueous solution onto the GO thin film, (iii) surface-confined electropolymerization (SCEP) of the adsorbed PyY molecules on the GO thin film. The as-prepared poly(PyY)/graphene nanocomposites thin films are characterized by using electroanalytical and spectroscopic techniques. Afterwards, the graphene-based polymeric dye thin film on ITO is used as an electrode in an electrochemical cell. Its performance is tested for electrochemical detection of nitrite. Under optimized conditions, the electrocatalytical effect of the nanocomposites thin film through electrochemical oxidation of nitrite is better than that of GO coated ITO.

Synthesis, Structure And Properties of Electrochemically Active Nanocomposites

DTIC Science & Technology

2003-05-01

milling. Detailed systematic impedance analysis , electronic conductivity measurement and high-resolution electron microscopy studies have shown that...carbon particles determined by TEM analysis . Results of the studies so far have shown that Sn and Si-based nanocomposites appear to be quite promising... Analysis of the As-milled Powders 117 2. Electrochemical Characteristics of Si/SiC Nanocomposites 120 3. Microstructural/Morphological Analysis of

Chemically designed Pt/PPy nano-composite for effective LPG gas sensor.

PubMed

Gaikwad, Namrata; Bhanoth, Sreenu; More, Priyesh V; Jain, G H; Khanna, P K

2014-03-07

Simultaneous in situ reduction of hexachloroplatinic acid by the amine group in the pyrrole monomer and oxidation of pyrrole to form polypyrrole (PPy) was examined. The reactions were performed at various temperatures to understand the degree of reduction of platinum precursor as well as doping of polypyrrole with Pt(II) chloro-complex. Spectroscopic images revealed different morphologies for the Pt/PPy nano-composite prepared at various temperatures. The as-prepared Pt/PPy nano-composite samples were tested for their ability to sense liquefied petroleum gas (LPG) which resulted in excellent sensing at relatively low temperature. The porous nature and ohmic contact between the PPy and platinum nanoparticles makes the as-prepared Pt/PPy nano-composite highly useful for sensors as well as electronic applications.

Performance of glucose/O2 enzymatic fuel cell based on supporting electrodes over-coated by polymer-nanogold particle composite with entrapped enzymes

NASA Astrophysics Data System (ADS)

Huo, W. S.; Zeng, H.; Yang, Y.; Zhang, Y. H.

2017-03-01

Enzymatic electrodes over-coated by thin film of nano-composite made up of polymer and functionalized nano-gold particle was prepared. Glucose/O2 membrane-free enzymatic fuel cell based on nano-composite based electrodes with incorporated glucose oxidase and laccase was assembled. This enzymatic fuel cell exhibited high energy out-put density even when applied in human serum. Catalytic cycle involved in enzymatic fuel cell was limited by oxidation of glucose occurred on bioanode resulting from impact of sophisticated interaction between active site in glucose oxidase and nano-gold particle on configuration of redox center of enzyme molecule which crippled catalytic efficiency of redox protein.

Synthesis of graphene oxide-copper molybdate (GO-CuM) nanocomposites for photocatalytic application

NASA Astrophysics Data System (ADS)

Singh, Gajendar; Bhargava, V. Sai; Sharma, Manu

2018-05-01

Transition metal molybdates (TMBs) MMoO4 (M=Ni, Cu, Fe, Zn, Co, etc.) based nanocomposites have been considered as remarkable materials in the field of electronics, optics, catalysis, supercapicitors and energy storage devices. Nanocomposites of TMBs with graphene oxide have also been chosen as an effective material in photocatalytic application. GO-CuM nanocomposites were synthesized by ultra-sonication method at RT, followed by reflux route for preparation of CuM and GO by modified Hemmer's method. As prepared nanocomposites were characterized using analytical techniques such as PXRD, SEM, FT-IR and UV-Visible spectroscopy. The enhanced photocatalytic activity of Methylene blue (MB) dye was observed by GO-CuM nanocomposites as compared to pure copper molybdate. GO-CuM nanocomposites show high photodegradation rate (0.094 min-1) whereas CuM was degraded only 30 % with the rate of 0.0029 min-1. The high photocatalytic efficiency is due to the presence of graphene oxide that helps to delay the charge recombination in photocatalytic reaction The effect of the different amount of graphene oxide on the photocatalytic activity of as prepared photocatalyst has also been investigated.

Dielectric characteristics of CaCu3Ti4O12/P(VDF-TrFE) nanocomposites

NASA Astrophysics Data System (ADS)

Zhang, Lin; Shan, Xiaobing; Wu, Peixuan; Cheng, Z.-Y.

2012-06-01

Composite thin film is highly desirable for the dielectric applications. In order to develop composite thin film, a nanocomposite, in which nanosized CaCu3Ti4O12 (CCTO) particles are used as filler and P(VDF-TrFE) 55/45 mol% copolymer is used as polymer matrix, is investigated. The contents of CCTO in the nanocomposites range from 0% to 50 vol%. The dielectric property of these nanocomposites was characterized at frequencies ranging from 100 Hz to 1 MHz and at temperatures ranging from 200 K to 370 K. A dielectric constant of 62 with a loss of 0.05 was obtained in nanocomposite with 50 vol% CCTO at room temperature at 1 kHz. At the phase transition temperature (˜340 K) of the copolymer, a dielectric constant of 150 with a loss less than 0.1 was obtained in this nanocomposite. It is found that the dielectric loss of the nanocomposites is dominated by the polymer which has a relaxation process. Comparing to composites made using microsized CCTO, the nanocomposites exhibit a much lower dielectric loss and a lower dielectric constant. This indicates that the nanosized CCTO particles have a lower dielectric constant than the microsized CCTO particles.

Effect of hydrolysed cellulose nanowhiskers on properties of montmorillonite/polylactic acid nanocomposites.

PubMed

Arjmandi, Reza; Hassan, Azman; Haafiz, M K M; Zakaria, Zainoha; Islam, Md Saiful

2016-01-01

Polylactic acid (PLA) nanocomposites reinforced with hybrid montmorillonite/cellulose nanowhiskers [MMT/CNW(SO4)] were prepared by solution casting. The CNW(SO4) nanofiller was first isolated from microcrystalline cellulose using acid hydrolysis treatment. PLA/MMT/CNW(SO4) hybrid nanocomposites were prepared by the addition of various amounts of CNW(SO4) [1-9 parts per hundred parts of polymer (phr)] into PLA/MMT nanocomposite at 5 phr MMT content, based on highest tensile strength values as reported previously. The biodegradability, thermal, tensile, morphological, water absorption and transparency properties of PLA/MMT/CNW(SO4) hybrid nanocomposites were investigated. The Biodegradability, thermal stability and crystallinity of hybrid nanocomposites increased compared to PLA/MMT nanocomposite and neat PLA. The highest tensile strength of hybrid nanocomposites was obtained by incorporating 1 phr CNW(SO4) [∼ 36 MPa]. Interestingly, the ductility of hybrid nanocomposites increased significantly by 87% at this formulation. The Young's modulus increased linearly with increasing CNW(SO4) content. This is due to the relatively good dispersion of nanofillers in the hybrid nanocomposites, as revealed by transmission electron microscopy. Fourier transform infrared spectroscopy indicated the formation of some polar interactions. In addition, water resistance of the hybrid nanocomposites improved and the visual transparency of neat PLA film did not affect by addition of CNW(SO4). Copyright © 2015 Elsevier B.V. All rights reserved.

Facile preparation of multifunctional carbon nanotube/magnetite/polyaniline nanocomposite offering a strong option for efficient solid-phase microextraction coupled with GC-MS for the analysis of phenolic compounds.

PubMed

Tafazoli, Zahra; Azar, Parviz Aberoomand; Tehrani, Mohammad Saber; Husain, Syed Waqif

2018-04-20

The aim of this study the synthesis of a highly efficient organic-inorganic nanocomposite. In this research, the carbon nanotube/magnetite/polyaniline nanocomposite was successfully prepared through a facile route. Monodisperse magnetite nanospheres were prepared through the coprecipitation route, and polyaniline nanolayer as a modified shell with a high surface area was synthesized by an in situ growth route and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy. The prepared nanocomposite was immobilized on a stainless-steel wire for the fabrication of the solid-phase microextraction fiber. The combination of headspace solid-phase microextraction using carbon nanotube/magnetite/polyaniline nanocomposite fiber with gas chromatography and mass spectrometry can achieve a low limit of detection and can be applied to determine phenolic compounds in water samples. The effects of the extraction and desorption parameters including extraction temperature and time, ionic strength, stirring rate, pH, and desorption temperature and time have been studied. Under the optimum conditions, the dynamic linear range was 0.01-500 ng mL -1 and the limits of detection of phenol, 4-chlorophenol, 2,6-dichlorophenol, and 2,4,6-trichlorophenol were the lowest (0.008 ng mL -1 ) for three times. The coefficient of determination of all calibration curves was more than 0.990. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Selective Clay Placement Within a Silicate-Clay Epoxy Blend Nanocomposite

NASA Technical Reports Server (NTRS)

Miller, Sandi G (Inventor)

2013-01-01

A clay-epoxy nanocomposite may be prepared by dispersing a layered clay in an alkoxy epoxy, such as a polypropylene oxide based epoxide before combining the mixture with an aromatic epoxy to improve the nanocomposite's thermal and mechanical properties.

Magnetic α-Fe2O3/MCM-41 nanocomposites: preparation, characterization, and catalytic activity for methylene blue degradation.

PubMed

Ursachi, Irina; Stancu, Alexandru; Vasile, Aurelia

2012-07-01

Catalysts based on nanosized magnetic iron oxide stabilized inside the pore system of ordered mesoporous silica MCM-41 have been prepared. The obtained materials were characterized by powder X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and N(2) adsorption-desorption isotherm. XRD analysis showed that the obtained materials consist from the pure hematite crystalline phase (α-Fe(2)O(3)) dispersed within ordered mesoporous silica MCM-41. Magnetic measurements show that the obtained nanocomposites exhibit at room temperature weak ferromagnetic behavior with slender hysteresis. The catalytic activity of the magnetic α-Fe(2)O(3)/MCM-41 nanocomposites was evaluated by the degradation of methylene blue (MB) aqueous solution. For this purpose, an ultrasound-assisted Fenton-like process was used. The effect of solution pH on degradation of MB was investigated. The results indicated that US-H(2)O(2)-α-Fe(2)O(3)/MCM-41 nanocomposite system is effective for the degradation of MB, suggesting its great potential in removal of dyes from wastewater. It was found that the degradation rate of MB increases with decrease in the pH value of the solution. Copyright © 2012 Elsevier Inc. All rights reserved.

Facile fabrication of epoxy-TiO2 nanocomposites: A critical analysis of TiO2 impact on mechanical properties and toughening mechanisms.

PubMed

Goyat, M S; Rana, S; Halder, Sudipta; Ghosh, P K

2018-01-01

Optimized ultrasonic assisted dispersion of un-functionalized titanium dioxide (TiO 2 ) nanoparticles (0.5-20wt%) into epoxy resin is reported. The investigation shows that there is a direct relation among nanoparticles content, inter-particle spacing and cluster size of the particles on the glass transition temperature (T g ) and tensile properties of the prepared nanocomposites. A significant improvement in tensile strength and modulus with minimal detrimental effect on the toughness was observed for the prepared composites, where compared to pristine epoxy resins, about 26% and 18% improvement in tensile strength and strain-to-break %, respectively, was observed for 10wt% particles loading, whereas a maximum improvement of about 54% for tensile toughness was observed for 5wt% particles loaded resins. The investigations found that a strong particle-matrix interface results in the enhancement of the mechanical properties due to leading toughening mechanisms such as crack deflection, particle pull out and plastic deformation. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation of Cu2O-Reduced Graphene Nanocomposite Modified Electrodes towards Ultrasensitive Dopamine Detection

PubMed Central

He, Quanguo; Liu, Jun; Liu, Xiaopeng; Li, Guangli; Deng, Peihong; Liang, Jing

2018-01-01

Cu2O-reduced graphene oxide nanocomposite (Cu2O-RGO) was used to modify glassy carbon electrodes (GCE), and applied for the determination of dopamine (DA). The microstructure of Cu2O-RGO nanocomposite material was characterized by scanning electron microscope. Then the electrochemical reduction condition for preparing Cu2O-RGO/GCE and experimental conditions for determining DA were further optimized. The electrochemical behaviors of DA on the bare electrode, RGO- and Cu2O-RGO-modified electrodes were also investigated using cyclic voltammetry in phosphate-buffered saline solution (PBS, pH 3.5). The results show that the oxidation peaks of ascorbic acid (AA), dopamine (DA), and uric acid (UA) could be well separated and the peak-to-peak separations are 204 mV (AA-DA) and 144 mV (DA-UA), respectively. Moreover, the linear response ranges for the determination of 1 × 10−8 mol/L~1 × 10−6 mol/L and 1 × 10−6 mol/L~8 × 10−5 mol/L with the detection limit 6.0 × 10−9 mol/L (S/N = 3). The proposed Cu2O-RGO/GCE was further applied to the determination of DA in dopamine hydrochloride injections with satisfactory results. PMID:29329206

Hydroxyapatite-alginate nanocomposite as drug delivery matrix for sustained release of ciprofloxacin.

PubMed

Venkatasubbu, G Devanand; Ramasamy, S; Ramakrishnan, V; Kumar, J

2011-12-01

Hydroxyapatite is a bioceramic which has a wide range of medical application for bone diseases. To enhance its usage, we have prepared ciprofloxacin loaded nano hydroxyapatite (HA) composite with a natural polymer, alginate, using wet chemical method at low temperature. The prepared composites were analyzed by various physicochemical methods. The results show that the nano HA crystallites are well intact with the alginate macromolecules. For the composite system FT-IR and micro Raman results are reported in this paper. Studies on the drug loading and drug release have been done. The drug is pre-adsorbed onto the ceramic particle before the formation of composite. The thermal behavior of composite has been studied using thermo gravimetric analysis (TGA). This work, reports that the nanocomposite prepared under optimum condition could prolong the release of ciprofloxacin compared with the ciprofloxacin loaded hydroxyapatite.

Functional Iron Oxide-Silver Hetero-Nanocomposites: Controlled Synthesis and Antibacterial Activity

NASA Astrophysics Data System (ADS)

Trang, Vu Thi; Tam, Le Thi; Van Quy, Nguyen; Huy, Tran Quang; Thuy, Nguyen Thanh; Tri, Doan Quang; Cuong, Nguyen Duy; Tuan, Pham Anh; Van Tuan, Hoang; Le, Anh-Tuan; Phan, Vu Ngoc

2017-06-01

Iron oxide-silver nanocomposites are of great interest for their antibacterial and antifungal activities. We report a two-step synthesis of functional magnetic hetero-nanocomposites of iron oxide nanoparticles and silver nanoparticles (Fe3O4-Ag). Iron oxide nanoparticles were prepared first by a co-precipitation method followed by the deposition of silver nanoparticles via a hydrothermal route. The prepared Fe3O4-Ag hetero-nanocomposites were characterized by x-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy and vibrating sample magnetometry. Their antibacterial activities were investigated by using paper-disc diffusion and direct-drop diffusion methods. The results indicate that the Fe3O4-Ag hetero-nanocomposites exhibit excellent antibacterial activities against two Gram-negative bacterial strains ( Salmonella enteritidis and Klebsiella pneumoniae).

Recent progress on preparation and properties of nanocomposites from recycled polymers: a review.

PubMed

Zare, Yasser

2013-03-01

Currently, the growing consumption of polymer products creates the large quantities of waste materials resulting in public concern in the environment and people life. Nanotechnology is assumed the important technology in the current century. Recently, many researchers have tried to develop this new science for polymer recycling. In this article, the application of different nanofillers in the recycled polymers such as PET, PP, HDPE, PVC, etc. and the attributed composites and blends is studied. The morphological, mechanical, rheological and thermal properties of prepared nanocomposites as well as the future challenges are extensively discussed. The present article determines the current status of nanotechnology in the polymer recycling which guide the future studies in this attractive field. Copyright © 2012 Elsevier Ltd. All rights reserved.

Thermoreversibly Cross-Linked EPM Rubber Nanocomposites with Carbon Nanotubes

PubMed Central

Criscitiello, Francesco; van Essen, Machiel; Araya-Hermosilla, Rodrigo; Migliore, Nicola; Lenti, Mattia; Raffa, Patrizio

2018-01-01

Conductive rubber nanocomposites were prepared by dispersing conductive nanotubes (CNT) in thermoreversibly cross-linked ethylene propylene rubbers grafted with furan groups (EPM-g-furan) rubbers. Their features were studied with a strong focus on conductive and mechanical properties relevant for strain-sensor applications. The Diels-Alder chemistry used for thermoreversible cross-linking allows for the preparation of fully recyclable, homogeneous, and conductive nanocomposites. CNT modified with compatible furan groups provided nanocomposites with a relatively large tensile strength and small elongation at break. High and low sensitivity deformation experiments of nanocomposites with 5 wt % CNT (at the percolation threshold) displayed an initially linear sensitivity to deformation. Notably, only fresh samples displayed a linear response of their electrical resistivity to deformations as the resistance variation collapsed already after one cycle of elongation. Notwithstanding this mediocre performance as a strain sensor, the advantages of using thermoreversible chemistry in a conductive rubber nanocomposite were highlighted by demonstrating crack-healing by welding due to the joule effect on the surface and the bulk of the material. This will open up new technological opportunities for the design of novel strain-sensors based on recyclable rubbers. PMID:29360772

Comparison of In Situ Polymerization and Solution-Dispersion Techniques in the Preparation of Polyimide/Montmorillonite (MMT) Nanocomposites

PubMed Central

Ahmad, Mansor Bin; Gharayebi, Yadollah; Salit, Mohd. Sapuan; Hussein, Mohd. Zobir; Shameli, Kamyar

2011-01-01

In this paper, Polyimide/Montmorillonite Nanocomposites (PI/MMT NCs), based on aromatic diamine (4-Aminophenyl sulfone) (APS) and aromatic dianhydride (3,3′,4,4′-benzophenonetetracarboxylic dianhydride) (BTDA) were prepared using in situ polymerization and solution-dispersion techniques. The prepared PI/MMT NCs films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The XRD results showed that at the content of 1.0 wt % Organo Montmorillonite (OMMT) for two techniques and 3.0 wt % OMMT for the in situ polymerization technique, the OMMT was well-intercalated, exfoliated and dispersed into polyimide matrix. The OMMT agglomerated when its amount exceeded 10 wt % and 3.0 wt % for solution-dispersion and in situ polymerization techniques respectively. These results were confirmed by the TEM images of the prepared PI/MMT NCs. The TGA thermograms indicated that thermal stability of prepared PI/MMT NCs were increased with the increase of loading that, the effect is higher for the samples prepared by in situ polymerization technique. PMID:22016643

Comparison of in situ polymerization and solution-dispersion techniques in the preparation of Polyimide/Montmorillonite (MMT) Nanocomposites.

PubMed

Ahmad, Mansor Bin; Gharayebi, Yadollah; Salit, Mohd Sapuan; Hussein, Mohd Zobir; Shameli, Kamyar

2011-01-01

In this paper, Polyimide/Montmorillonite Nanocomposites (PI/MMT NCs), based on aromatic diamine (4-Aminophenyl sulfone) (APS) and aromatic dianhydride (3,3',4,4'-benzophenonetetracarboxylic dianhydride) (BTDA) were prepared using in situ polymerization and solution-dispersion techniques. The prepared PI/MMT NCs films were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The XRD results showed that at the content of 1.0 wt % Organo Montmorillonite (OMMT) for two techniques and 3.0 wt % OMMT for the in situ polymerization technique, the OMMT was well-intercalated, exfoliated and dispersed into polyimide matrix. The OMMT agglomerated when its amount exceeded 10 wt % and 3.0 wt % for solution-dispersion and in situ polymerization techniques respectively. These results were confirmed by the TEM images of the prepared PI/MMT NCs. The TGA thermograms indicated that thermal stability of prepared PI/MMT NCs were increased with the increase of loading that, the effect is higher for the samples prepared by in situ polymerization technique.

Chemical Synthesis and Optical Properties of CdS Poly(Lactic Acid) Nanocomposites and Their Transparent Fluorescent Films

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

Wang, Cai-Feng; Cheng, Yu-Peng; Xie, He-Yi

2011-01-01

This paper describes the chemical synthesis of cadmium sulfide (CdS) polymer nanocomposites by covalently grafting poly(lactic acid) (PLA) onto the surfaces of CdS nanocrystals (NCs). Synthesis of the nanocomposites involved two steps. Lactic acid (LA) capped CdS NCs were first prepared by reacting cadmium chloride (CdCl2) with sodium sulfide (Na2S) using LA as the organic ligand in H2O/N,N-dimethylformamide (DMF) solution. Next CdS PLA nanocomposites were formed by in situ ring-opening polymerization of lactide on the surface of modified CdS NCs. Transparent fluorescent films were then successfully prepared by blending as-prepared CdS PLA nanocomposites with high-molecular-weight PLA. The as-prepared CdS NCsmore » and their nanocomposites were studied by transmission electron microscopic imaging, thermogravimetric analyses, and spectroscopic measurements (ultraviolet-visible absorption and photoluminescence). The spectroscopic studies revealed that the CdS polymer nanocomposites exhibited good optical properties in terms of their photoluminescence and transparency.« less

Black phosphorus quantum dots/attapulgite nanocomposite with enhanced photocatalytic performance

NASA Astrophysics Data System (ADS)

Li, Xiazhang; Li, Feihong; Lu, Xiaowang; Zuo, Shixiang; Zhuang, Ziheng; Yao, Chao

Novel black phosphorus quantum dots/attapulgite (BPQDs/ATP) nanocomposites were prepared via a facile hydrothermal-deposition method. TEM showed that BPQDs dispersed evenly on the surface of ATP with uniform particle size about 5nm. UV-Vis revealed that the BPQDs/ATP composite showed wider visible light absorption range as compared with pure ATP. The photocatalytic activity was evaluated by degradation of bisphenol A (BPA). Results showed that BPQDs/ATP reached 90% degradation rate under solar light irradiation for 180min. The coherent heterostructure formed by BPQDs and ATP was responsible for the enhanced photocatalytic performance, due to the sensitization effect of BPQDs and the facilitation of charges separation.

Preparation, characterization, and biological properties of organic-inorganic nanocomposite coatings on titanium substrates prepared by sol-gel.

PubMed

Catauro, Michelina; Bollino, Flavia; Papale, Ferdinando

2014-02-01

When surface-reactive (bioactive) coatings are applied to medical implants by means of the sol-gel dip-coating technique, the biological proprieties of the surface of the implant can be locally modified to match the properties of the surrounding tissues to provide a firm fixation of the implant. The aim of this study has been to synthesize, via sol-gel, organoinorganic nanoporous materials and to dip-coat a substrate to use in dental applications. Different systems have been prepared consisting of an inorganic zirconium-based matrix, in which a biodegradable polymer, the poly-ε-caprolactone was incorporated in different percentages. The materials synthesized by the sol-gel process, before gelation, when they were still in sol phase, have been used to coat a titanium grade 4 (Ti-4) substrate to change its surface biological properties. Thin films have been obtained by means of the dip-coating technique. A microstructural analysis of the obtained coatings was performed using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy. The biological proprieties have been investigated by means of tests in vitro. The bone-bonding capability of the nanocomposite films has been evaluated by examining the appearance of apatite on their surface when plunged in a simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma. The examination of apatite formation on the nanocomposites, after immersion in SBF, has been carried out by SEM equipped with energy-dispersive X-ray spectroscopy. To evaluate cells-materials interaction, human osteosarcoma cell line (Saos-2) has been seeded on specimens and cell vitality evaluated by WST-8 assay. © 2013 Wiley Periodicals, Inc.

Aspergilli Response to Benzalkonium Chloride and Novel-Synthesized Fullerenol/Benzalkonium Chloride Nanocomposite

PubMed Central

Unković, Nikola; Ljaljević Grbić, Milica; Stupar, Miloš; Vukojević, Jelena; Janković, Vesna; Jović, Danica; Djordjević, Aleksandar

2015-01-01

A comprehensive comparative analysis of antifungal potential of benzalkonium chloride and newly synthesized fullerenol/benzalkonium chloride nanocomposite was conducted to assess the possible impact of carbon-based nanocarrier on antimicrobial properties of the commonly used biocide. Physical characterization of synthesized nanocomposite showed zeta potential of +37.4 mV and inhomogeneous particles size distribution, with nanocomposite particles' dimensions within 30–143 nm and maximum number of particles at 44 nm. The effect of pure and fullerenol nanocarrier-bound biocide was evaluated in eight Aspergillus species. In mycelial growth assay, nanocomposite was more potent, as fungicidal effect of 1.04/0.6 μg mL−1 was obtained in all but one of the isolates (A. niger), while proportional concentration of pure biocide (0.6 μg mL−1) completely inhibited mycelial growth of only three Aspergillus species. However, conidia appear to be less susceptible to nanocomposite treatment, as lower fungistatic (MIC) and fungicidal (MFC) concentrations were obtained with biocide alone (MIC in range from 0.03 to 0.15 μg mL−1 and MFC from 0.075 to 0.45 μg mL−1). To a different degree, both substances stimulated aflatoxin B1 production and inhibited ochratoxin A synthesis. Very low mycelium biomass yield, in range from 1.0 to 3.0 mg dry weight, was documented in both biocide and nanocomposite enriched medium. PMID:26295057

Multifunctional nanocomposites of chitosan, silver nanoparticles, copper nanoparticles and carbon nanotubes for water treatment: Antimicrobial characteristics.

PubMed

Morsi, Rania E; Alsabagh, Ahmed M; Nasr, Shimaa A; Zaki, Manal M

2017-04-01

Multifunctional nanocomposites of chitosan with silver nanoparticles, copper nanoparticles and carbon nanotubes either as bi- or multifunctional nanocomposites were prepared. Change in the overall morphology of the prepared nanocomposites was observed; carbon nanotubes, Ag NPs and Cu NPs are distributed homogeneously inside the polymer matrix individually in the case of the bi-nanocomposites while a combination of different dimensional shapes; spherical NPs and nanotubes was observed in the multifunctional nanocomposite. Multifunctional nanocomposites has a higher antimicrobial activity, in relative short contact times, against both Gram negative and Gram positive bacteria; E. coli, Staphylococcus aureus; respectively in addition to the fungal strain; Aspergillus flavus isolated from local wastewater sample. The nanocomposites are highly differentiable at the low contact time and low concentration; 1% concentration of the multifunctional nanocomposite is very effective against the tested microbes at contact time of only 10min. Copyright © 2017 Elsevier B.V. All rights reserved.

Method for preparing spherical thermoplastic particles of uniform size

DOEpatents

Day, J.R.

1975-11-17

Spherical particles of thermoplastic material of virtually uniform roundness and diameter are prepared by cutting monofilaments of a selected diameter into rod-like segments of a selected uniform length which are then heated in a viscous liquid to effect the formation of the spherical particles.

Vegetable Oil-Based Hyperbranched Thermosetting Polyurethane/Clay Nanocomposites

PubMed Central

2009-01-01

The highly branched polyurethanes and vegetable oil-based polymer nanocomposites have been showing fruitful advantages across a spectrum of potential field of applications.Mesua ferreaL. seed oil-based hyperbranched polyurethane (HBPU)/clay nanocomposites were prepared at different dose levels by in situ polymerization technique. The performances of epoxy-cured thermosetting nanocomposites are reported for the first time. The partially exfoliated structure of clay layers was confirmed by XRD and TEM. FTIR spectra indicate the presence of H bonding between nanoclay and the polymer matrix. The present investigation outlines the significant improvement of tensile strength, scratch hardness, thermostability, water vapor permeability, and adhesive strength without much influencing impact resistance, bending, and elongation at break of the nanocomposites compared to pristine HBPU thermoset. An increment of two times the tensile strength, 6 °C of melting point, and 111 °C of thermo-stability were achieved by the formation of nanocomposites. An excellent shape recovery of about 96–99% was observed for the nanocomposites. Thus, the formation of partially exfoliated clay/vegetable oil-based hyperbranched polyurethane nanocomposites significantly improved the performance. PMID:20596546

Vegetable Oil-Based Hyperbranched Thermosetting Polyurethane/Clay Nanocomposites.

PubMed

Deka, Harekrishna; Karak, Niranjan

2009-04-25

The highly branched polyurethanes and vegetable oil-based polymer nanocomposites have been showing fruitful advantages across a spectrum of potential field of applications. Mesua ferrea L. seed oil-based hyperbranched polyurethane (HBPU)/clay nanocomposites were prepared at different dose levels by in situ polymerization technique. The performances of epoxy-cured thermosetting nanocomposites are reported for the first time. The partially exfoliated structure of clay layers was confirmed by XRD and TEM. FTIR spectra indicate the presence of H bonding between nanoclay and the polymer matrix. The present investigation outlines the significant improvement of tensile strength, scratch hardness, thermostability, water vapor permeability, and adhesive strength without much influencing impact resistance, bending, and elongation at break of the nanocomposites compared to pristine HBPU thermoset. An increment of two times the tensile strength, 6 degrees C of melting point, and 111 degrees C of thermo-stability were achieved by the formation of nanocomposites. An excellent shape recovery of about 96-99% was observed for the nanocomposites. Thus, the formation of partially exfoliated clay/vegetable oil-based hyperbranched polyurethane nanocomposites significantly improved the performance.

Development of bimetal oxide doped multifunctional polymer nanocomposite for water treatment

NASA Astrophysics Data System (ADS)

Saxena, Swati; Saxena, Umesh

2016-08-01

Bimetal oxide doped polymer nanocomposite was developed using Alumina and Iron (III) Oxide as nanoparticles with Nylon 6, 6 and Poly (sodium-4-styrenesulphonate) as polymer matrix for removal of pollutants from water. The blend sample of polymers was prepared by well established solution blending technique and their nanocomposite samples were prepared through dispersion technique during the solution casting of blend sample. The fabricated composites were characterized adopting FTIR, XRD, FESEM and EDX techniques. XRD and FESEM were used for morphological characterization of nano phase, while FTIR and EDX analysis were adopted for characterization of chemical moieties in composites. In the study of pollutant removal capacities of prepared composites, 6 % nanocomposite provided the best results. It exhibited the maximum removal of all parameters. The removal of total alkalinity was 66.67 %, total hardness 42.85 %, calcium 66.67 %, magnesium 25 %, chloride 58.66 %, nitrate 34.78 %, fluoride 63.85 %, TDS 41.27 % and EC was up to the level of 41.37 % by this composite. The study is a step towards developing multifunctional, cost-effective polymer nanocomposites for water remediation applications.

Silk-regulated hierarchical hollow magnetite/carbon nanocomposite spheroids for lithium-ion battery anodes.

PubMed

Sheng, Weiqin; Zhu, Guobin; Kaplan, David L; Cao, Chuanbao; Zhu, Hesun; Lu, Qiang

2015-03-20

Hierarchical olive-like structured carbon-Fe3O4 nanocomposite particles composed of a hollow interior and a carbon coated surface are prepared by a facile, silk protein-assisted hydrothermal method. Silk nanofibers as templates and carbon precursors first regulate the formation of hollow Fe2O3 microspheres and then they are converted into carbon by a reduction process into Fe3O4. This process significantly simplifies the fabrication and carbon coating processes to form complex hollow structures. When tested as anode materials for lithium-ion batteries, these hollow carbon-coated particles exhibit high capacity (900 mAh g(-1)), excellent cycle stability (180 cycles) and rate performance due to their unique hierarchical hollow structure and carbon coating.

New biocide guanidine-containing nanocomposites

NASA Astrophysics Data System (ADS)

Gorbunova, Marina; Lemkina, Larisa

2014-08-01

New water-soluble nanocomposites based on Ag and copolymers of 2,2-diallyl-1,1,3,3-tetraethylguanidiniumchloride with N-vinylpyrrolidone [poly(AGC-VP)] and vinylacetate [poly(AGC-VA)] have been developed. The average silver particle size ranged from 52 to 62 nm for poly(AGC-VA) and from 28 to 30 nm for poly(AGC-VP), with the corresponding UV-vis absorption peak position at 405-410 nm. The using of copolymers resulted in improvement in bactericide properties of composites. Following these results, the newly developed nanocomposite scaffold may be considered for new water-soluble medicines and biocides.

Preparation of UV-protective kefiran/nano-ZnO nanocomposites: physical and mechanical properties.

PubMed

Shahabi-Ghahfarrokhi, Iman; Khodaiyan, Faramarz; Mousavi, Mohammad; Yousefi, Hossein

2015-01-01

In this study, we investigated the effect of ZnO nanoparticles (ZN) as a UV-protective agent of kefiran biopolymers. Our results showed that with increasing ZN content, the tensile strength, elongation at break, and tensile energy to break the kefiran film and nanocomposites also increased. Kefiran nanocomposites with a ZN content higher than 2% produced a UV-protective film with good visual properties, low sensibility to water, and low water-vapor permeability. The thermal properties of all specimens, analyzed by DSC, showed that the ZN content had a negative effect on Tg and a positive effect on nanocomposites' melting point. TEM, SEM micrography and XRD spectrum analysis confirmed the hypothesis that ZNs act like a ball bearing, making movement of kefiran chains easier and increasing elongation at break, while simultaneously decreasing the Tg of kefiran nanocomposites. Copyright © 2014 Elsevier B.V. All rights reserved.

Fabrication of metal/semiconductor nanocomposites by selective laser nano-welding.

PubMed

Yu, Huiwu; Li, Xiangyou; Hao, Zhongqi; Xiong, Wei; Guo, Lianbo; Lu, Yongfeng; Yi, Rongxing; Li, Jiaming; Yang, Xinyan; Zeng, Xiaoyan

2017-06-01

A green and simple method to prepare metal/semiconductor nanocomposites by selective laser nano-welding metal and semiconductor nanoparticles was presented, in which the sizes, phases, and morphologies of the components can be maintained. Many types of nanocomposites (such as Ag/TiO 2 , Ag/SnO 2 , Ag/ZnO 2 , Pt/TiO 2 , Pt/SnO 2 , and Pt/ZnO) can be prepared by this method and their corresponding performances were enhanced.

High photocatalytic activity of Fe2O3/TiO2 nanocomposites prepared by photodeposition for degradation of 2,4-dichlorophenoxyacetic acid.

PubMed

Lee, Shu Chin; Lintang, Hendrik O; Yuliati, Leny

2017-01-01

Two series of Fe 2 O 3 /TiO 2 samples were prepared via impregnation and photodeposition methods. The effect of preparation method on the properties and performance of Fe 2 O 3 /TiO 2 for photocatalytic degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under UV light irradiation was examined. The Fe 2 O 3 /TiO 2 nanocomposites prepared by impregnation showed lower activity than the unmodified TiO 2 , mainly due to lower specific surface area caused by heat treatment. On the other hand, the Fe 2 O 3 /TiO 2 nanocomposites prepared by photodeposition showed higher photocatalytic activity than the unmodified TiO 2 . Three times higher photocatalytic activity was obtained on the best photocatalyst, Fe 2 O 3 (0.5)/TiO 2 . The improved activity of TiO 2 after photodeposition of Fe 2 O 3 was contributed to the formation of a heterojunction between the Fe 2 O 3 and TiO 2 nanoparticles that improved charge transfer and suppressed electron-hole recombination. A further investigation on the role of the active species on Fe 2 O 3 /TiO 2 confirmed that the crucial active species were both holes and superoxide radicals. The Fe 2 O 3 (0.5)/TiO 2 sample also showed good stability and reusability, suggesting its potential for water purification applications.

Preparation and antibacterial properties of Ag@polydopamine/graphene oxide sheet nanocomposite

NASA Astrophysics Data System (ADS)

Zhou, Hao; Liu, Yunfang; Chi, Weidong; Yu, Changyuan; Yu, Yingjie

2013-10-01

Immobilization of silver nanoparticles (Ag NPs) on poly-dopamine (PDA) functionalized graphene oxide sheets (GOSs) were carried out by an easy in situ reduction method. The PDA layer was coated on the surface of the GOSs via the self-polymerization of dopamine under atmosphere condition. The PDA layer not only works as the chemisorption and reduction sites for silver ions to form Ag NPs but also stabilizes them. High-resolution transmission electron microscopy observation shows that the average size of the Ag NPs anchored on the PDA/GOS composite is about 2.8 nm. The inhibition zone diameter of the Ag@PDA/GOS nanocomposite is about 23.7 mm, whereas said diameter of the Ag NPs is only 18.5 mm. The minimum bactericidal concentration of the Ag@PDA/GOS nanocomposite is about 25 μg/ml that is only half of said concentration of the Ag NPs. The Ag@PDA/GOS nanocomposite exhibits an excellent antibacterial property.

Facile hydrothermal preparation of titanium dioxide decorated reduced graphene oxide nanocomposite

PubMed Central

Chang, Betty Yea Sze; Huang, Nay Ming; An’amt, Mohd Nor; Marlinda, Abdul Rahman; Norazriena, Yusoff; Muhamad, Muhamad Rasat; Harrison, Ian; Lim, Hong Ngee; Chia, Chin Hua

2012-01-01

A simple single-stage approach, based on the hydrothermal technique, has been introduced to synthesize reduced graphene oxide/titanium dioxide nanocomposites. The titanium dioxide nanoparticles are formed at the same time as the graphene oxide is reduced to graphene. The triethanolamine used in the process has two roles. It acts as a reducing agent for the graphene oxide as well as a capping agent, allowing the formation of titanium dioxide nanoparticles with a narrow size distribution (~20 nm). Transmission electron micrographs show that the nanoparticles are uniformly distributed on the reduced graphene oxide nanosheet. Thermogravimetric analysis shows the nanocomposites have an enhanced thermal stability over the original components. The potential applications for this technology were demonstrated by the use of a reduced graphene oxide/titanium dioxide nanocomposite-modified glassy carbon electrode, which enhanced the electrochemical performance compared to a conventional glassy carbon electrode when interacting with mercury(II) ions in potassium chloride electrolyte. PMID:22848166

Controlled fabrication of luminescent and magnetic nanocomposites

NASA Astrophysics Data System (ADS)

Ma, Yingxin; Zhong, Yucheng; Fan, Jing; Huang, Weiren

2018-03-01

Luminescent and magnetic multifunctional nanocomposite is in high demand and widely used in many scales, such as drug delivery, bioseparation, chemical/biosensors, and so on. Although lots of strategies have been successfully developed for the demand of multifunctional nanocomposites, it is not easy to prepare multifunctional nanocomposites by using a simple method, and satisfy all kinds of demands simultaneously. In this work, via a facile and versatile method, luminescent nanocrystals and magnetic nanoparticles were successfully synthesized through self-assembly under vigorous stirring and ultrasonic treatment. These multifunctional nanocomposites are not only water stable but also find wide application such as magnetic separation and concentration with a series of moderate speed, multicolor fluorescence at different emission wavelength, high efficiency of the excitation and emission, and so on. By changing different kinds of luminescent nanocrystals and controlling the amount of luminescent and magnetic nanoparticles, a train of multifunctional nanocomposites was successfully fabricated via a versatile and robust method.

Preparation of a concentrated organophyllosilicate and nanocomposite composition

DOEpatents

Chaiko, David J.; Niyogi, Suhas G.

2007-01-16

The present invention provide methods for producing a low moisture organophyllosilicate composition using monomers, oligomers, or polymers to displace water associated with the organophyllosilicates in an aqueous organophyllosilicate slurry or filter cake. The invention additionally provides methods for producing organophyllosilicate nanocomposites from the concentrated organophyllosilicate compositions by dispersing the compositions in a polymer matrix.

One-step electrochemical deposition of a graphene-ZrO 2 nanocomposite: Preparation, characterization and application for detection of organophosphorus agents

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

Du, Dan; Liu, Juan; Zhang, Xiao-Yan

2011-04-27

This paper described the preparation, characterization, and electrochemical properties of a graphene-ZrO 2 nanocomposite (GZN) and its application for both the enrichment and detection of methyl parathion (MP). GZN was fabricated using electrochemical deposition and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), which showed the successful formation of nanocomposites. Due to the strong affinity to the phosphoric group and the fast electron-transfer kinetics of GZN, both the extraction and electrochemical detection of organophosphorus (OP) agents at the same GZN modified electrochemical sensor was possible. The combination of solid-phase extractionmore » and stripping voltammetric analysis allowed fast, sensitive, and selective determination of MP in garlic samples. The stripping response was highly linear over the MP concentrations ranging from 0.5 ng mL -1 to 100 ng mL -1, with a detection limit of 0.1 ng mL -1. This new nanocomposite-based electrochemical sensor provides an opportunity to develop a field-deployable, sensitive, and quantitative method for monitoring exposure to OPs.« less

Physicochemical properties and bioactivity of freeze-cast chitosan nanocomposite scaffolds reinforced with bioactive glass.

PubMed

Pourhaghgouy, Masoud; Zamanian, Ali; Shahrezaee, Mostafa; Masouleh, Milad Pourbaghi

2016-01-01

Chitosan based nanocomposite scaffolds were prepared by freeze casting method through blending constant chitosan concentration with different portions of synthesized bioactive glass nanoparticles (BGNPs). Transmission Electron Microscopy (TEM) image showed that the particles size of bioactive glass (64SiO2.28CaO.8P2O5) prepared by sol-gel method was approximately less than 20 nm. Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray Diffraction (XRD) analysis showed proper interfacial bonding between BGNPs and chitosan polymers. Scanning Electron Microscopy (SEM) images depicted a unidirectional structure with homogenous distribution of BGNPs among chitosan matrix associated with the absence of pure chitosan scaffold's wall pores after addition of only 10 wt.% BGNPs. As the BGNP content increased from 0 to 50 wt.%, the compressive strength and compressive module values increased from 0.034 to 0.419 MPa and 0.41 to 10.77 MPa, respectively. Biodegradation study showed that increase in BGNP content leads to growth of weight loss amount. The in vitro biomineralization studies confirmed the bioactive nature of all nanocomposites. Amount of 30 wt.% BGNPs represented the best concentration for absorption capacity and bioactivity behaviors. Copyright © 2015. Published by Elsevier B.V.

Synthesis, characterization and low temperature electrical conductivity of Polyaniline/NiFe2O4 nanocomposites

NASA Astrophysics Data System (ADS)

Prasanna, G. D.; Prasad, V. B.; Jayanna, H. S.

2015-02-01

Conducting polymer/ferrite nanocomposites with an organized structure provide a new functional hybrid between organic and inorganic materials. The most popular among the conductive polymers is the polyaniline (PANI) due to its wide application in different fields. In the present work nickel ferrite (NiFe2O4) nanoparticles were prepared by sol-gel citrate-nitrate method with an average size of 21.6nm. PANI/NiFe2O4 nanoparticles were synthesized by a simple general and inexpensive in-situ polymerization in the presence of NiFe2O4 nanoparticles. The effects of NiFe2O4 nanoparticles on the dc-electrical properties of polyaniline were investigated. The structural components in the nanocomposites were identified from Fourier Transform Infrared (FTIR) spectroscopy. The crystalline phase of nanocomposites was characterized by X-Ray Diffraction (XRD). The Scanning Electron Micrograph (SEM) reveals that there was some interaction between the NiFe2O4 particles and polyaniline and the nanocomposites are composed of polycrystalline ferrite nanoparticles and PANI. The dc conductivity of polyaniline/NiFe2O4 nanocomposites have been measured as a function of temperature in the range of 80K to 300K. It is observed that the room temperature conductivity cRT decreases with increase in the relative content of NiFe2O4. The experimental data reveals that the resistivity increases for all composites with decrease of temperature exhibiting semiconductor behaviour.

Characterization of SWNT based Polystyrene Nanocomposites

NASA Astrophysics Data System (ADS)

Mitchell, Cynthia; Bahr, Jeffrey; Tour, James; Arepalli, Sivaram; Krishnamoorti, Ramanan

2003-03-01

Polystyrene nanocomposites with functionalized single walled carbon nanotubes (SWNTs), prepared by the in-situ generation and addition of organic diazonium compounds, were characterized using a range of structural and dynamic methods. These were contrasted to the properties of polystyrene composites prepared with unfunctionalized SWNTs at the same loadings. The functionalized nanocomposites demonstrated a percolated SWNT network structure at concentrations of 1 vol SWNT based composites at similar loadings of SWNT exhibited behavior comparable to that of the unfilled polymer. This formation of the SWNT network structure is because of the improved compatibility between the SWNTs and the polymer matrix due to the functionalization. Further structural evidence for the compatibility of the modified SWNTs and the polymer matrix will be discussed in the presentation.

Magneto-optical properties of α-Fe2O3@ZnO nanocomposites prepared by the high energy ball-milling technique

NASA Astrophysics Data System (ADS)

Chaudhury, Chandana Roy; Roychowdhury, Anirban; Das, Anusree; Das, Dipankar

2016-05-01

Magnetic-fluorescent nanocomposites (NCs) with 10 wt% of α-Fe2O3 in ZnO have been prepared by the high energy ball-milling. The crystallite sizes of α-Fe2O3 and ZnO in the NCs are found to vary from 65 nm to 20 nm and 47 nm to 15 nm respectively as milling time is increased from 2 to 30 h. XRD analysis confirms presence of α-Fe2O3 and ZnO in pure form in all the NCs. UV-vis study of the NCs shows a continuous blue-shift of the absorption peak and a steady increase of band gap of ZnO with increasing milling duration that are assigned to decreasing particle size of ZnO in the NCs. Photoluminescence (PL) spectra of the NCs reveal three weak emission bands in the visible region at 421, 445 and 485 nm along with the strong near band edge emission at 391 nm. These weak emission bands are attributed to different defect - related energy levels e.g. Zn-vacancy, Zn interstitial and oxygen vacancy. Dc and ac magnetization measurements show presence of weakly interacting superparamagnetic (SPM) α-Fe2O3 particles in the NCs. 57Fe-Mössbauer study confirms presence of SPM hematite in the sample milled for 30 h. Positron annihilation lifetime measurements indicate presence of cation vacancies in ZnO nanostructures confirming results of PL studies.

Gold surface supported spherical liposome-gold nano-particle nano-composite for label free DNA sensing.

PubMed

Bhuvana, M; Narayanan, J Shankara; Dharuman, V; Teng, W; Hahn, J H; Jayakumar, K

2013-03-15

Immobilization of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) liposome-gold nano-particle (DOPE-AuNP) nano-composite covalently on 3-mercaptopropionic acid (MPA) on gold surface is demonstrated for the first time for electrochemical label free DNA sensing. Spherical nature of the DOPE on the MPA monolayer is confirmed by the appearance of sigmoidal voltammetric profile, characteristic behavior of linear diffusion, for the MPA-DOPE in presence of [Fe(CN)(6)](3-/4-) and [Ru(NH(3))(6)](3+) redox probes. The DOPE liposome vesicle fusion is prevented by electroless deposition of AuNP on the hydrophilic amine head groups of the DOPE. Immobilization of single stranded DNA (ssDNA) is made via simple gold-thiol linkage for DNA hybridization sensing in the presence of [Fe(CN)(6)](3-/4-). The sensor discriminates the hybridized (complementary target hybridized), un-hybridized (non-complementary target hybridized) and single base mismatch target hybridized surfaces sensitively and selectively without signal amplification. The lowest target DNA concentration detected is 0.1×10(-12)M. Cyclic voltammetry (CV), electrochemical impedance (EIS), differential pulse voltammetry (DPV) and quartz crystal microbalance (QCM) techniques are used for DNA sensing on DOPE-AuNP nano-composite. Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS) and Ultraviolet-Visible (UV) spectroscopic techniques are used to understand the interactions between the DOPE, AuNP and ssDNA. The results indicate the presence of an intact and well defined spherical DOPE-AuNP nano-composite on the gold surface. The method could be applied for fabrication of the surface based liposome-AuNP-DNA composite for cell transfection studies at reduced reagents and costs. Copyright © 2012 Elsevier B.V. All rights reserved.

Preparation of hierarchical porous Zn-salt particles and their superhydrophobic performance

NASA Astrophysics Data System (ADS)

Gao, Dahai; Jia, Mengqiu

2015-12-01

Superhydrophobic surfaces arranged by hierarchical porous particles were prepared using modified hydrothermal routes under the effect of sodium citrate. Two particle samples were generated in the medium of hexamethylenetetramine (P1) and urea (P2), respectively. X-ray diffraction, scanning electron microscope, and transmission electron microscope were adopted for the investigation, and results revealed that the P1 and P2 particles are porous microspheres with crosslinked extremely thin (10-30 nm) sheet crystals composed of Zn5(OH)8Ac2·2H2O and Zn5(CO3)2(OH)6, respectively. The prepared particles were treated with a fluoroethylene vinyl ether derivative and studied using Fourier transform infrared spectroscopy and energy-dispersive X-ray spectrometer. Results showed that the hierarchical surfaces of these particles were combined with low-wettable fluorocarbon layers. Moreover, the fabricated surface composed of the prepared hierarchical particles displayed considerably high contact angles, indicating great superhydrophobicity for the products. The wetting behavior of the particles was analyzed with a theoretical wetting model in comparison with that of chestnut-like ZnO products obtained through a conventional hydrothermal route. Correspondingly, this study provided evidence that high roughness surface plays a great role in superhydrophobic behavior.

Dielectric properties and effect of electrical aging on space charge accumulation in polyimide/TiO2 nanocomposite films

NASA Astrophysics Data System (ADS)

Zha, Jun-Wei; Dang, Zhi-Min; Song, Hong-Tao; Yin, Yi; Chen, George

2010-11-01

In situ polymerized polyimide/TiO2 (PI/TiO2) nanocomposite films with good electrical aging resistance are studied. Space charge distribution in the PI/TiO2 nanocomposite films are measured using the pulsed electroacoustic method. Dielectric properties of the films are measured in the frequency range of 102 Hz-106 Hz by an impedance analyzer (Agilent 4294A) at room temperature. These nanocomposite films are also characterized by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). It is demonstrated that the nano-TiO2 particles strongly affect dielectric breakdown, lifetime and space charge distribution, and increase the voltage endurance of the nanocomposite films significantly. SEM analyses show that the nanocomposite films are destroyed after corona aging. The relation of space charge distribution with the concentration of the nano-TiO2 particles and the aging time is explored. Results show that an increase in dielectric permittivity of the nanocomposite films is observed with increasing filler concentration. However, the accumulation of space charge decreases with increasing nano-TiO2 particles concentration for the same corona aging time, and depends on the dielectric permittivity of the nanocomposite films.

A Combination of Boron Nitride Nanotubes and Cellulose Nanofibers for the Preparation of a Nanocomposite with High Thermal Conductivity.

PubMed

Zeng, Xiaoliang; Sun, Jiajia; Yao, Yimin; Sun, Rong; Xu, Jian-Bin; Wong, Ching-Ping

2017-05-23

With the current development of modern electronics toward miniaturization, high-degree integration and multifunctionalization, considerable heat is accumulated, which results in the thermal failure or even explosion of modern electronics. The thermal conductivity of materials has thus attracted much attention in modern electronics. Although polymer composites with enhanced thermal conductivity are expected to address this issue, achieving higher thermal conductivity (above 10 W m -1 K -1 ) at filler loadings below 50.0 wt % remains challenging. Here, we report a nanocomposite consisting of boron nitride nanotubes and cellulose nanofibers that exhibits high thermal conductivity (21.39 W m -1 K -1 ) at 25.0 wt % boron nitride nanotubes. Such high thermal conductivity is attributed to the high intrinsic thermal conductivity of boron nitride nanotubes and cellulose nanofibers, the one-dimensional structure of boron nitride nanotubes, and the reduced interfacial thermal resistance due to the strong interaction between the boron nitride nanotubes and cellulose nanofibers. Using the as-prepared nanocomposite as a flexible printed circuit board, we demonstrate its potential usefulness in electronic device-cooling applications. This thermally conductive nanocomposite has promising applications in thermal interface materials, printed circuit boards or organic substrates in electronics and could supplement conventional polymer-based materials.

Holographic patterning of organic-inorganic photopolymerizable nanocomposites

NASA Astrophysics Data System (ADS)

Sakhno, Oksana V.; Goldenberg, Leonid M.; Smirnova, Tatiana N.; Stumpe, J.

2009-09-01

We present here novel easily processible organic-inorganic nanocomposites suitable for holographic fabrication of diffraction optical elements (DOE). The nanocomposites are based on photocurable acrylate monomers and inorganic nanoparticles (NP). The compatibility of inorganic NP with monomers was achieved by capping the NP surface with proper organic shells. Surface modification allows to introduce up to 50wt.% of inorganic NP in organic media. Depending on the NP nature (metal oxides, phosphates, semiconductors, noble metals) and their properties, the materials for both efficient DOE and multifunctional elements can be designed. Organic-inorganic composites prepared have been successfully used for the effective inscription of periodic volume refractive index structures using the holographic photopolymerization method. The nanocomposite preparation procedure, their properties and optical performance of holographic gratings are reported. The use of functional NP makes it possible to obtain effective holographic gratings having additional physical properties such as light-emission or NLO. Some examples of such functional polymer-NP structures and their possible application fields are presented. The combination of easy photo-patterning of soft organic compounds with physical properties of inorganic materials in new nanocomposites and the flexibility of the holographic patterning method allow the fabrication of mono- and multifunctional one- and multi-dimensional passive or active optical and photonic elements.

Multifunctional Polymer Nanocomposites

NASA Astrophysics Data System (ADS)

Galaska, Alexandra Maria; Song, Haixiang; Guo, Zhanhu

With more awareness of energy conversion/storage and saving, different strategies have been developed to utilize the sustainable and renewable energy. Introducing nanoscale fillers can make inert polymer matrix possess unique properties to satisfy certain functions. For example, alumina nanoparticles have strengthened the weak thermosetting polymers. A combined mixture of carbon nanofibers and magnetite nanoparticles have made the inert epoxy sensitive for magnetic field for sensing applications. Introducing silica nanoparticles into conductive polymers such as polyaniline has enhanced the giant magnetoresistance behaviors. The introduced nanoparticles have made the transparent polymer have the electromagnetic interference (EMI) shielding function while reduce the density significantly. With the desired miniaturization, the materials combining different functionalities have become importantly interesting. In this talk, methodologies to prepare nanocomposites and their effects on the produced nanocomposites will be discussed. A variety of advanced polymer nanocomposites will be introduced. Unique properties including mechanical, electrical, magnetoresistance etc. and the applications for environmental remediation, energy storage/saving, fire retardancy, electromagnetic interference shielding, and electronic devices will be presented.

Cadmium Telluride-Titanium Dioxide Nanocomposite for Photodegradation of Organic Substance.

PubMed

Ontam, Areeporn; Khaorapapong, Nithima; Ogawa, Makoto

2015-12-01

Cadmium telluride-titanium dioxide nanocomposite was prepared by hydrothermal reaction of sol-gel derived titanium dioxide and organically modified cadmium telluride. The crystallinity of titanium dioxide in the nanocomposite was higher than that of pure titanium dioxide obtained by the reaction under the same temperature and pressure conditions, showing that cadmium telluride induced the crystallization of titanium dioxide. Diffuse reflectance spectrum of the nanocomposite showed the higher absorption efficiency in the UV-visible region due to band-gap excitation of titanium dioxide. The nanocomposite significantly showed the improvement of photocatalytic activity for 4-chlorophenol with UV light.

Single-Stroke Synthesis of Tin Sulphide/Oxide Nanocomposites Within Engineering Thermoplastic and Their Humidity Response.

PubMed

Adkar, Dattatraya; Adhyapak, Parag; Mulik, Uttamrao; Jadkar, Sandesh; Vutova, Katia; Amalnerkar, Dinesh

2018-05-01

SnS nanostructured materials have attracted enormous interest due to their important properties and potential application in low cost solar energy conversion systems and optical devices. From the perspective of SnS based device fabrication, we offer single-stroke in-situ technique for the generation of Sn based sulphide and oxide nanostructures inside the polymer network via polymer-inorganic solid state reaction route. In this method, polyphenylene sulphide (PPS)-an engineering thermoplastic-acts as chalcogen source as well as stabilizing matrix for the resultant nano products. Typical solid state reaction was accomplished by simply heating the physical admixtures of the tin salts (viz. tin acetate/tin chloride) with PPS at the crystalline melting temperature (285 °C) of PPS in inert atmosphere. The synthesized products were characterized by using various physicochemical characterization techniques. The prima facie observations suggest the concurrent formation of nanocrystalline SnS with extraneous oxide phase. The TEM analysis revealed formation of nanosized particles of assorted morphological features with polydispersity confined to 5 to 50 nm. However, agglomerated particles of nano to submicron size were also observed. The humidity sensing characterization of these nanocomposites was also performed. The resistivity response with the level of humidity (20 to 85% RH) was compared for these nanocomposites. The linear response was obtained for both the products. Nevertheless, the nanocomposite product obtained from acetate precursor showed higher sensitivity towards the humidity than that of one prepared from chloride precursor.

High energy density in PVDF nanocomposites using an optimized nanowire array.

PubMed

Guo, Ru; Luo, Hang; Liu, Weiwei; Zhou, Xuefan; Tang, Lin; Zhou, Kechao; Zhang, Dou

2018-06-22

TiO2 nanowire arrays are often utilized to prepare high performance polymer nanocomposites, however, the contribution to the energy density is limited due to their non-ferroelectric characteristics. A nanocomposite with an optimized nanowire array combining the ferroelectric properties of lead zirconate titanate (PZT) with TiO2, readily forming nanowires (denoted as a TiO2-P nanowire array), is prepared to enhance the permittivity. Poly(vinylidene fluoride) (PVDF) is used as the polymer matrix due to its high breakdown strength, e.g. 600-700 kV mm-1. As a result, the permittivity and breakdown electric field reach 53 at 1 kHz and 550 kV mm-1, respectively. Therefore, the nanocomposites achieve a higher discharge energy density of 12.4 J cm-3 with excellent cycle stability, which is the highest among nanocomposites based on a nanowire array as a filler in a PVDF matrix. This work provides not only a feasible approach to obtain high performance dielectric nanocomposites, but also a wide range of potential applications in the energy storage and energy harvesting fields.

Morphology and Admittance Spectroscopy of Cellulose Acetate/Graphene Quantum Dots Nanocomposites

NASA Astrophysics Data System (ADS)

Arthisree, D.; Joshi, Girish M.; Kumar, Annamalai Senthil

Graphene quantum dots (GQDs) are considered as fascinating materials feasible for biological, optoelectronic devices, energy and environmental applications. Casting nanocomposite films for technological application is a challenging research interest. Cellulose acetate (CA) is one of the most abundant, economic, environmental friendly and biodegradable biomaterials. It has been found that CA is a preferred composite matrix to prepare recasting films, due to its efficient antifouling feature. In the present investigation, we exhibited preparation of CA/GQD nanocomposite by solution blending as a function of GQD loading 0.1-0.5wt.%. Morphology and electrical properties were examined as a function of GQD loading. The nanocomposite was characterized by impedance spectroscopy, and the measured admittance (Y) was plotted against temperature across broadband frequency. The magnitude of Y exhibits direct relation under the varying temperature. The morphology of the nanocomposites was observed by atomic force microscope technique in contact mode. Collective observation from our results is that it can be revealed that CA/GQD nanocomposites are suitable for thermal sensing applications.

Green synthesis of in situ electrodeposited rGO/MnO2 nanocomposite for high energy density supercapacitors

PubMed Central

Rusi; Majid, S. R.

2015-01-01

This paper presents the preparation of in situ electrodeposited rGO/MnO2 nanocomposite as a binder-free electrode for supercapacitor application. The work describes and evaluates the performance of prepared electrode via green and facile electrodeposition technique of in situ rGO/MnO2-glucose carbon nanocomposites. The carbon content in the composite electrode increased after GO and D (+) glucose solution has been added in the deposition electrolyte. This study found that a suitable concentration of D (+) glucose in the deposition electrolyte can slow down the nucleation process of MnO2 particles and lead to uniform and ultrathin nanoflakes structure. The optimize electrode exhibited low transfer resistance and resulted on excellent electrochemical performance in three electrolyte systems viz. Na2SO4, KOH and KOH/K3Fe(CN)6 redox electrolytes. The optimum energy density and power density were 1851 Whkg−1 and 68 kWkg−1 at current density of 20 Ag−1 in mixed KOH/K3Fe(CN)6 electrolyte. PMID:26537363

Green synthesis of in situ electrodeposited rGO/MnO2 nanocomposite for high energy density supercapacitors.

PubMed

Rusi; Majid, S R

2015-11-05

This paper presents the preparation of in situ electrodeposited rGO/MnO2 nanocomposite as a binder-free electrode for supercapacitor application. The work describes and evaluates the performance of prepared electrode via green and facile electrodeposition technique of in situ rGO/MnO2-glucose carbon nanocomposites. The carbon content in the composite electrode increased after GO and D (+) glucose solution has been added in the deposition electrolyte. This study found that a suitable concentration of D (+) glucose in the deposition electrolyte can slow down the nucleation process of MnO2 particles and lead to uniform and ultrathin nanoflakes structure. The optimize electrode exhibited low transfer resistance and resulted on excellent electrochemical performance in three electrolyte systems viz. Na2SO4, KOH and KOH/K3Fe(CN)6 redox electrolytes. The optimum energy density and power density were 1851 Whkg(-1) and 68 kWkg(-1) at current density of 20 Ag(-1) in mixed KOH/K3Fe(CN)6 electrolyte.

Green synthesis of in situ electrodeposited rGO/MnO2 nanocomposite for high energy density supercapacitors

NASA Astrophysics Data System (ADS)

Rusi; Majid, S. R.

2015-11-01

This paper presents the preparation of in situ electrodeposited rGO/MnO2 nanocomposite as a binder-free electrode for supercapacitor application. The work describes and evaluates the performance of prepared electrode via green and facile electrodeposition technique of in situ rGO/MnO2-glucose carbon nanocomposites. The carbon content in the composite electrode increased after GO and D (+) glucose solution has been added in the deposition electrolyte. This study found that a suitable concentration of D (+) glucose in the deposition electrolyte can slow down the nucleation process of MnO2 particles and lead to uniform and ultrathin nanoflakes structure. The optimize electrode exhibited low transfer resistance and resulted on excellent electrochemical performance in three electrolyte systems viz. Na2SO4, KOH and KOH/K3Fe(CN)6 redox electrolytes. The optimum energy density and power density were 1851 Whkg-1 and 68 kWkg-1 at current density of 20 Ag-1 in mixed KOH/K3Fe(CN)6 electrolyte.

Design and Development of Novel Hierarchically Ordered Block Copolymer-Magnetoelectric Particle Nanocomposites

DTIC Science & Technology

2012-06-08

microscopy (JEOL 1200EX STEM). The volume fraction of BaTiO3 nanoparticles in the PS-BTO nanocomposites was determined by thermogravimetric analysis ...encapsulated in the 9.8±0.4-nm NP was approximately only 13.8% based on the thermogravimetric analysis (TGA) measurement (Supporting Material Section...the properties of the constituents and their spatial arrangement. Nanocomposites of polymer/ nanoparticle , formed by incorporating nanoparticles into

Facile fabrication of hollow mesosphere of crystalline SnO2 nanoparticles and synthesis of SnO2@SWCNTs@Reduced Graphene Oxide nanocomposite as efficient Pt-Free counter electrode for dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Khan, Muhammad Wasim; Yao, Jixin; Zhang, Kang; Zuo, Xueqin; Yang, Qun; Tang, Huaibao; Ur Rehman, Khalid Mehmood; Li, Guang; Wu, Mingzai; Zhu, Kerong; Zhang, Haijun

2018-06-01

In this research, SnO2@SWCNTs@Reduced Graphene Oxide based nanocomposite was synthesized by a one step hydrothermal method and reported new cost effective platinum-free counter-electrodes (CEs) in dye-sensitized solar cells (DSSCs). The CEs were formed by using the nanocomposites with the help of a pipette using a doctor-blade technique. The efficiency of this nanocomposite revealed significant elctrocatalytic properties upon falling the triiodide, possessing to synergistic effect of SnO2 nano particles and improved conductivity when SWCNTs dispersed on graphene sheet. Therefore, the power conversion efficiency (PCE) of prepared SnO2@SWCNTs@RGO nanocomposite CE attained of (6.1%) in DSSCs which is equivalent to the value (6.2%) which attained to the value (6.2%) with pure Pt CE as a reference. SnO2@SWCNTs@RGO nanocomposite CEs give more stable catalytic activities for triiodide reduction than SnO2 and SWCNTs CEs in the cyclic voltammetry (CV) analysis. Furthermore, to the subsistence of graphene oxide, the nanocomposite acquired both higher stability and efficiency in the nanocomposite.

Preparation of nanocomposites resin from seed Pterodon emarginatus doped maghemite nanoparticles.

PubMed

Silveira, L B; Martins, Q S; Maia, J C; Santos, J G

2012-06-01

Electrical characterization and magnetic nanocomposite resin seeds Pterodon emarginatus (PE) doped with nanoparticles of maghemite and treated by different chemical processes is reported in this paper. The pure PE resin showed semiconducting characteristics probably the presence of natural iron oxide in its molecular structure. The analysis of Mössbauer spectra pure resin showed two magnetic sites presented on measurements made at temperature of 300 K. Six "LEDs" to have been doped maghemite nanoparticles forming concentrations of 2.6 x 10(15) to 1.56 x 10(16) particles/cm2 forming the LED-PEMN. In the presence of the applied current versus voltage (0 to 0.9 V) LED-PEMN shown semiconducting properties. In the presence of frequency versus voltage sample of pure resin and LED features small decrease. While samples of LED-PEMN suffers loss frequency linearly with concentration and voltage. The pure PE resin shows high resistance to the applied voltage while the LED-PEMN is observed linear increase with the strength and concentration of nanoparticles of maghemite.

Effect of cationic surfactants on characteristics and colorimetric behavior of polydiacetylene/silica nanocomposite as time-temperature indicator

NASA Astrophysics Data System (ADS)

Nopwinyuwong, Atchareeya; Kitaoka, Takuya; Boonsupthip, Waraporn; Pechyen, Chiravoot; Suppakul, Panuwat

2014-09-01

Polydiacetylene (PDA)/silica nanocomposites were synthesized by self-assembly method using polymerizable amphiphilic diacetylene monomers, 10,12-pentacosadiynoic acid (PCDA). Addition of cationic surfactants (PDADMAC and CTAB) to PDA/SiO2 nanocomposites induced higher intermolecular force which affected their size, shape and color transition. Pure PDA, PDA/SiO2, PDA/SiO2/PDADMAC and PDA/SiO2/CTAB were investigated by particle size analysis, TEM, SEM, UV-vis spectroscopy and FT-IR. It was found that the PDA/SiO2 nanocomposites exhibited slightly larger particle sizes than those of other samples. The PDA/SiO2 nanocomposites with a core-shell structure were almost regarded as spherical-shaped particles. Cationic surfactants, especially CTAB, presumably affected the particle size and shape of PDA/SiO2 nanocomposites due to the disruption of hydrogen bonding between PDA head group and ammonium group. The colorimetric response of both PDA/SiO2/surfactant and surfactant-free PDA/SiO2 aqueous solutions directly changed in relation to time and temperature; thus they were expected to be applied as a new polymer-based time-temperature indicator (TTI).

Preparation, characterization and conductivity study of nitro-mercurated styrene butadiene rubber/silver doped zinc oxide nanocomposites

NASA Astrophysics Data System (ADS)

Anilkumar, T.; Naik, Adarsh Ajith; Ramesan, M. T.

2017-06-01

Here we report the preparation of nitromercurated styrene butadiene rubber (NMSBR)/silver doped zinc oxide nanocomposite by inexpensive and ecofriendly two roll mill mixing. The composites were characterized by UV, FTIR, XRD, SEM, TGA and conductivity measurements. UV and FTIR spectrum indicated the interfacial interaction between the polymer and nanoparticles.XRD and SEM images showed the uniform arrangement of nanoparticles within the macromolecular chain. TGA study indicated the better thermal resistance of the composite. The dielectric properties and AC conductivity ofnanocomposites were much greater than nitromercurated SBR and they may be used as multifunctional materials for nanoelectronic devices.

Correlation between crystallization behaviour and interfacial interactions in plasticized PLA/POSS nanocomposites

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

Kodal, Mehmet, E-mail: mehmet.kodal@kocaeli.edu.tr; Şirin, Hümeyra; Özkoç, Güralp, E-mail: guralp.ozkoc@kocaeli.edu.tr

2016-03-09

In this study, the correlation between crystallization behavior and surface chemistry of polyhedral oligomeric silsesquioxanes (POSS) for plasticized poly(lactic acid) (PLA)/POSS nanocomposites was investigated. Four different kinds of POSS particles having different chemical structures were used. Poly(ethylene glycol) (PEG, 8000 g/mol) was utilized as the plasticiser. The nanocomposites were melt-compounded in an Xplore Instruments 15 cc twin screw microcompounder at 180°C barrel temperature and 100 rpm screw speed. Non-isothermal crystallization behaviour of PLA/PEG/POSS nanocomposites were evaluated from common kinetic models such as Avrami and Avrami-Ozawa and Kissinger by using the thermal data obtained from differantial scanning calorimetry (DSC). A polarized optical microscopemore » (POM) equipped with a hot-stage was used to examine the morphology during the crystal growth. In order to investigate the interfacial interactions between POSS particles and plasticized PLA, thermodynamic work of adhesion approach was adopted using the experimentally determined surface energies. A strong correlation was obtained between interfacial chemistry and the nucleation rate in plasticized PLA/POSS nanocomposites. It was found that the polar interactions were the dominating factor which determines the nucleation activity of the POSS particles.« less

Cellulose nanocrystals reinforced foamed nitrile rubber nanocomposites.

PubMed

Chen, Yukun; Zhang, Yuanbing; Xu, Chuanhui; Cao, Xiaodong

2015-10-05

Research on foamed nitrile rubber (NBR)/cellulose nanocrystals (CNs) nanocomposites is rarely found in the literatures. In this paper, CNs suspension and NBR latex was mixed to prepared the foamed NBR/CNs nanocomposites. We found that the CNs mainly located in the cell walls, effectively reinforcing the foamed NBR. The strong interaction between the CNs and NBR matrix restricted the mobility of NBR chains surrounding the CNs, hence increasing the crosslink density of the NBR matrix. CNs exhibited excellent reinforcement on the foamed NBR: a remarkable increase nearly 76% in the tensile strength of the foamed nanocomposites was achieved with a load of only 15 phr CNs. Enhanced mechanical properties make the foamed NBR/CNs nanocomposites a promising damping material for industrial applications with a potential to reduce the petroleum consumption. Copyright © 2015 Elsevier Ltd. All rights reserved.

Polymer Layered Silicate Nanocomposites: A Review

PubMed Central

Mittal, Vikas

2009-01-01

This review aims to present recent advances in the synthesis and structure characterization as well as the properties of polymer layered silicate nanocomposites. The advent of polymer layered silicate nanocomposites has revolutionized research into polymer composite materials. Nanocomposites are organic-inorganic hybrid materials in which at least one dimension of the filler is less than 100 nm. A number of synthesis routes have been developed in the recent years to prepare these materials, which include intercalation of polymers or pre-polymers from solution, in-situ polymerization, melt intercalation etc. The nanocomposites where the filler platelets can be dispersed in the polymer at the nanometer scale owing to the specific filler surface modifications, exhibit significant improvement in the composite properties, which include enhanced mechanical strength, gas barrier, thermal stability, flame retardancy etc. Only a small amount of filler is generally required for the enhancement in the properties, which helps the composite materials retain transparency and low density.

Graphene oxide-silica nanohybrids as fillers for PA6 based nanocomposites

NASA Astrophysics Data System (ADS)

Maio, A.; Fucarino, R.; Khatibi, R.; Botta, L.; Rosselli, S.; Bruno, M.; Scaffaro, R.

2014-05-01

Graphene oxide (GO) was prepared by oxidation of graphite flakes by a mixture of H2SO4/H3PO4 and KMnO4 based on Marcano's method. Two different masterbatches containing GO (33.3%) and polyamide-6 (PA6) (66.7%) were prepared both via solvent casting in formic acid and by melt mixing in a mini-extruder (Haake). The two masterbatches were then used to prepare PA6-based nanocomposites with a content of 2% in GO. For comparison, a nanocomposite by direct mixing of PA6 and GO (2%) and PA6/graphite nanocomposites were prepared, too. The oxidation of graphite into GO was assessed by X-ray diffraction (XRD), Micro-Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) analyses. All these techniques demonstrated the effectiveness of the graphite modification, since the results put into evidence that, after the acid treatment, interlayer distance, oxygen content and defects increased. SEM micrographs carried out on the nanocomposites, showed GO layers totally surrounded by polyamide-6, this feature is likely due to the strong interaction between the hydrophilic moieties located both on GO and on PA6. On the contrary, no interactions were observed when graphite was used as filler. Mechanical characterization, carried out by tensile and dynamic-mechanical tests, marked an improvement of the mechanical properties observed. Photoluminescence and EPR measurements were carried out onto nanoparticles and nanocomposites to study the nature of the interactions and to assess the possibility to use this class of materials as semiconductors or optical sensors.

Preparation of Metalloporphyrin-Bound Superparamagnetic Silica Particles via "Click" Reaction.

PubMed

Hollingsworth, Javoris V; Bhupathiraju, N V S Dinesh K; Sun, Jirun; Lochner, Eric; Vicente, M Graça H; Russo, Paul S

2016-01-13

A facile approach using click chemistry is demonstrated for immobilization of metalloporphyrins onto the surface of silica-coated iron oxide particles. Oleic-acid stabilized iron oxide nanocrystals were prepared by thermal decomposition of iron(III) acetylacetonate. Their crystallinity, morphology, and superparamagnetism were determined using X-ray diffraction, transmission electron microscopy, and a superconducting quantum interference device. Monodisperse core-shell particles were produced in the silica-coating of iron oxide via microemulsion synthesis. Surface modification of these particles was performed in two steps, which included the reaction of silica-coated iron oxide particles with 3-bromopropyltrichlorosilane, followed by azido-functionalization with sodium azide. Monoalkylated porphyrins were prepared using the Williamson ether synthesis of commercially available tetra(4-hydroxyphenyl) porphyrin with propargyl bromide in the presence of a base. (1)H NMR and matrix-assisted laser desorption ionization confirmed the identity of the compounds. The prepared monoalkyne porphyrins were zinc-metalated prior to their introduction to azide-functionalized, silica-coated iron oxide particles in the click reaction. X-ray photoelectron spectroscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy were used to characterize the surface chemistry after each step in the reaction. In addition, particle size was determined using dynamic light scattering and microscopy. The presented methodology is versatile and can be extended to other photoreactive systems, such as phthalocyanines and boron-dipyrromethane, which may lead to new materials for optical, photonic, and biological applications.

Synthesis of Transparent Aqueous ZrO2 Nanodispersion with a Controllable Crystalline Phase without Modification for a High-Refractive-Index Nanocomposite Film.

PubMed

Xia, Yi; Zhang, Cong; Wang, Jie-Xin; Wang, Dan; Zeng, Xiao-Fei; Chen, Jian-Feng

2018-05-30

The controllable synthesis of metal oxide nanoparticles is of fundamental and technological interest. In this article, highly transparent aqueous nanodispersion of ZrO 2 with controllable crystalline phase, high concentration, and long-term stability was facilely prepared without any modification via the reaction of inexpensive inorganic zirconium salt and sodium hydroxide in water under an acid surrounding, combined with hydrothermal treatment. The as-prepared transparent nanodispersion had an average particle size of 7 nm, a high stability of 18 months, and a high solid content of 35 wt %. ZrO 2 nanocrystals could be readily dispersed in many solvents with high polarity including ethanol, dimethyl sulfoxide, acetic acid, ethylene glycol, and N, N-dimethylformamide, forming stable transparent nanodispersions. Furthermore, highly transparent polyvinyl alcohol/ZrO 2 nanocomposite films with high refractive index were successfully prepared with a simple solution mixing route. The refractive index could be tuned from 1.528 to 1.754 (@ 589 nm) by changing the mass fraction (0-80 wt %) of ZrO 2 in transparent nanocomposite films.

Preparation, characterization, and nonlinear optical properties of hybridized graphene @ gold nanorods nanocomposites

NASA Astrophysics Data System (ADS)

Guo, Jia; Ning, Tingyin; Han, Yanshun; Sheng, Yingqiang; Li, Chonghui; Zhao, Xiaofei; Lu, Zhengyi; Man, Baoyuan; Jiao, Yang; Jiang, Shouzhen

2018-03-01

The methods of chemical vapor deposition (CVD) and seed-mediated growth were used to obtain graphene and gold nanorods (GNRs), respectively. We fabricate graphene @ gold nanorods (G@GNRs) nanocomposites by successively using dropping and transferring methods Through SEM, Raman spectra and TEM analysis, the number of graphene layers is 6-7. The diameter of gold nanorods (GNRs) is about 10 nm and the average aspect ratio is 6.5. In addition, we systematically investigate their nonlinear optical responses by using open-aperture Z-scan technique. In contrast with graphene and GNRs, the G@GNRs nanocomposites exhibit excellent nonlinear optical response with a modulation depth of about 51% and a saturable intensity of about 6.23 GW/cm2. The results suggest that the G@GNRs nanocomposites could potentially be used as an optical modulator in pulsed laser generation.

Water-assisted extrusion of bio-based PETG/clay nanocomposites

NASA Astrophysics Data System (ADS)

Lee, Naeun; Lee, Sangmook

2018-02-01

Bio-based polyethylene terephthalate glycol-modified (PETG)/clay nanocomposites were prepared using the water-assisted extrusion process. The effects of different types of clay and clay mixing methods (with or without the use of water) and the resulting nanocomposites properties were investigated by measuring the rheological and tensile properties and morphologies. The valuable properties were achieved when Cloisite 30B was mixed in a slurry state. The results of the X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies showed that the nano-clay was well dispersed within the PETG matrix. This shows that the slurry process could be an effective exfoliation method for many nanocomposites systems as well as for bio-based PETG/clay nanocomposites.

Analysis of the Barrier Properties of Polyimide-Silicate Nanocomposites

NASA Technical Reports Server (NTRS)

Campbell, Sandi; Johnston, J. Chris; Inghram, Linda; McCorkle, Linda; Silverman, Edward

2003-01-01

Montmorillonite clay was organically modified and dispersed into a thermoplastic (BPADA-BAPP) and a thermosetting (PMR-15) polyimide matrix. The barrier properties of the neat resins and the nanocomposites were evaluated. Reductions in gas permeability and water absorption were observed in thermoplastic polyimide nanocomposites. The thermosetting polyimide showed a reduction in weight loss during isothermal aging at 288 C. Carbon fabric (T650-35, 8 HS, 8 ply) composites were prepared using both the BPADE-BAPP and PMR-15 based nanocomposites. Dispersion of the layered silicate in the BPADA-BAPP matrix reduced helium permeability by up to 70 percent. The PMR-15/ silicate nanocomposite matrix had an increase in thermal oxidative stability of up to 25 percent.

Epoxy based nanocomposites with fully exfoliated unmodified clay: mechanical and thermal properties.

PubMed

Li, Binghai; Zhang, Xiaohong; Gao, Jianming; Song, Zhihai; Qi, Guicun; Liu, Yiqun; Qiao, Jinliang

2010-09-01

The unmodified clay has been fully exfoliated in epoxy resin with the aid of a novel ultrafine full-vulcanized powdered rubber. Epoxy/rubber/clay nanocomposites with exfoliated morphology have been successfully prepared. The microstructures of the nanocomposites were characterized by means of X-ray diffraction and transmission electron microscopy. It was found that the unmodified clay was fully exfoliated and uniformly dispersed in the resulting nanocomposite. Characterizations of mechanical properties revealed that the impact strength of this special epoxy/rubber/clay nanocomposite increased up 107% over the neat epoxy resin. Thermal analyses showed that thermal stability of the nanocomposite was much better than that of epoxy nanocomposite based on organically modified clay.

Preparation and characterization of an iron oxide-hydroxyapatite nanocomposite for potential bone cancer therapy.

PubMed

Sneha, Murugesan; Sundaram, Nachiappan Meenakshi

2015-01-01

Recently, multifunctional magnetic nanostructures have been found to have potential applications in biomedical and tissue engineering. Iron oxide nanoparticles are biocompatible and have distinctive magnetic properties that allow their use in vivo for drug delivery and hyperthermia, and as T2 contrast agents for magnetic resonance imaging. Hydroxyapatite is used frequently due to its well-known biocompatibility, bioactivity, and lack of toxicity, so a combination of iron oxide and hydroxyapatite materials could be useful because hydroxyapatite has better bone-bonding ability. In this study, we prepared nanocomposites of iron oxide and hydroxyapatite and analyzed their physicochemical properties. The results suggest that these composites have superparamagnetic as well as biocompatible properties. This type of material architecture would be well suited for bone cancer therapy and other biomedical applications.

Preparation of highly stable fullerene C60 decorated graphene oxide nanocomposite and its sensitive electrochemical detection of dopamine in rat brain and pharmaceutical samples.

PubMed

Thirumalraj, Balamurugan; Palanisamy, Selvakumar; Chen, Shen-Ming; Lou, Bih-Show

2016-01-15

The research community has continuously paid much attention on the preparation of hybrid of carbon nanomaterials owing to combine their unique properties. Herein, we report the preparation of highly stable fullerene C60 (C60) wrapped graphene oxide (GO) nanocomposite by using a simple sonication method. The fabricated GO-C60 nanocomposite modified glassy carbon electrode shows a good sensitivity and lower oxidation overpotential towards dopamine (DA) than that of pristine GO and C60. The fabricated sensor detects the DA in the linear response range of 0.02-73.5μM. The limit of detection is estimated to be 0.008μM based on 3σ with a sensitivity of 4.23μAμM(-1)cm(-2). The fabricated sensor also exhibits other features such as good selectivity, stability, reproducibility and repeatability. The proposed sensor exhibits good practicality towards the detection of DA in rat brain and commercial DA injection samples. Copyright © 2015 Elsevier Inc. All rights reserved.

Polyethylene organo-clay nanocomposites: the role of the interface chemistry on the extent of clay intercalation/exfoliation.

PubMed

Mainil, Michaël; Alexandre, Michaël; Monteverde, Fabien; Dubois, Philippe

2006-02-01

High density polyethylene (HDPE)/clay nanocomposites have been prepared using three different functionalized polyethylene compatibilizers: an ethylene/vinyl acetate copolymer, a polyethylene grafted with maleic anhydride functions and a (styrene-b-ethylene/butylene-b-styrene) block copolymer. The nanocomposites were prepared via two different routes: (1) the dispersion in HDPE of a masterbatch prepared from the compatibilizer and the clay or (2) the direct melt blending of the three components. For each compatibilizer, essentially intercalated nanocomposites were formed as determined by X-ray diffraction and transmission electron microscopy. With the ethylene/vinyl acetate copolymer, a significant delamination of the intercalated clay in thin stacks was observed. This dispersion of thin intercalated stacks within the polymer matrix allowed increasing significantly the stiffness and the flame resistance of the nanocomposite. A positive effect of shear rate and blending time has also been put into evidence, especially for the process based on the masterbatch preparation, improving both the formation of thin stacks of intercalated clay and the mechanical properties and the flame resistance of the formed nanocomposites.

Graphene oxide--MnO2 nanocomposites for supercapacitors.

PubMed

Chen, Sheng; Zhu, Junwu; Wu, Xiaodong; Han, Qiaofeng; Wang, Xin

2010-05-25

A composite of graphene oxide supported by needle-like MnO(2) nanocrystals (GO-MnO(2) nanocomposites) has been fabricated through a simple soft chemical route in a water-isopropyl alcohol system. The formation mechanism of these intriguing nanocomposites investigated by transmission electron microscopy and Raman and ultraviolet-visible absorption spectroscopy is proposed as intercalation and adsorption of manganese ions onto the GO sheets, followed by the nucleation and growth of the crystal species in a double solvent system via dissolution-crystallization and oriented attachment mechanisms, which in turn results in the exfoliation of GO sheets. Interestingly, it was found that the electrochemical performance of as-prepared nanocomposites could be enhanced by the chemical interaction between GO and MnO(2). This method provides a facile and straightforward approach to deposit MnO(2) nanoparticles onto the graphene oxide sheets (single layer of graphite oxide) and may be readily extended to the preparation of other classes of hybrids based on GO sheets for technological applications.

A Theoretically Informed Model for the Rheology of Entangled Block Copolymer Nanocomposites

NASA Astrophysics Data System (ADS)

Su, Yongrui; Ramirez-Hernandez, Abelardo; Peters, Brandon; de Pablo, Juan J.

2014-03-01

The addition of nanoparticles to block copolymer systems has been shown to have important effects on their equilibrium structure and properties. Less is known about the non-equilibrium behavior of block polymer nanocomposites. A new particle-based, theoretically informed coarse-grained model for multicomponent nanocomposites is proposed to examine the effects of nanoparticles on the rheology of entangled block copolymer melts. Entanglements are treated at the two-molecule level, through slip-springs that couple the dynamics of neighboring pairs of chains. The inclusion of slip-springs changes the polymer dynamics from unentangled to entangled. The nanoparticles are functionalized with short polymer chains that can entangle with the copolymers. We study the nonlinear rheology of the resulting nanocomposites under shear flow with a dissipative particle dynamics (DPD) thermostat.

Modifying Silicates for Better Dispersion in Nanocomposites

NASA Technical Reports Server (NTRS)

Campbell, Sandi

2005-01-01

An improved chemical modification has been developed to enhance the dispersion of layered silicate particles in the formulation of a polymer/silicate nanocomposite material. The modification involves, among other things, the co-exchange of an alkyl ammonium ion and a monoprotonated diamine with interlayer cations of the silicate. The net overall effects of the improved chemical modification are to improve processability of the nanocomposite and maximize the benefits of dispersing the silicate particles into the polymer. Some background discussion is necessary to give meaning to a description of this development. Polymer/silicate nanocomposites are also denoted polymer/clay composites because the silicate particles in them are typically derived from clay particles. Particles of clay comprise layers of silicate platelets separated by gaps called "galleries." The platelet thickness is 1 nm. The length varies from 30 nm to 1 m, depending on the silicate. In order to fully realize the benefits of polymer/silicate nanocomposites, it is necessary to ensure that the platelets become dispersed in the polymer matrices. Proper dispersion can impart physical and chemical properties that make nanocomposites attractive for a variety of applications. In order to achieve nanometer-level dispersion of a layered silicate into a polymer matrix, it is typically necessary to modify the interlayer silicate surfaces by attaching organic functional groups. This modification can be achieved easily by ion exchange between the interlayer metal cations found naturally in the silicate and protonated organic cations - typically protonated amines. Long-chain alkyl ammonium ions are commonly chosen as the ion-exchange materials because they effectively lower the surface energies of the silicates and ease the incorporation of organic monomers or polymers into the silicate galleries. This completes the background discussion. In the present improved modification of the interlayer silicate surfaces

A dataset for preparing pristine graphene-palladium nanocomposites using swollen liquid crystal templates

NASA Astrophysics Data System (ADS)

Vats, Tripti; Siril, Prem Felix

2017-12-01

Pristine graphene (G) has not received much attention as a catalyst support, presumably due to its relative inertness as compared to reduced graphene oxide (RGO). In the present work, we used swollen liquid crystals (SLCs) as nano-reactors for graphene-palladium nanocomposites synthesis. The 'soft' confinement of SLCs directs the growth of palladium (Pd) nanoparticles over the G sheets. In this dataset we include all the parameters and details of different techniques used for the characterization of G, SLCs and synthesized G-Pd nanocomposites. The synthesized G-palladium nanocomposites (Pd-G) exhibited improved catalytic activity compared with Pd-RGO and Pd nanoparticles, in the hydrogenation of nitrophenols and C-C coupling reactions.

Calcium-doped ceria/titanate tabular functional nanocomposite by layer-by-layer coating method

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

Liu, Xiang W., E-mail: lxwluck@gmail.co; Devaraju, M.K.; Yin, Shu

2010-07-15

Ca-doped ceria (CDC)/tabular titanate (K{sub 0.8}Li{sub 0.27}Ti{sub 1.73}O{sub 4}, TT) UV-shielding functional nanocomposite with fairly uniform CDC coating layers was prepared through a polyelectrolyte-associated layer-by-layer (LbL) coating method. TT with lepidocrocite-like layered structure was used as the substrate, poly (diallyldimethylammonium chloride) (PDDA) was used as a coupling agent, CDC nanoparticles were used as the main UV-shielding component. CDC/TT nanocomposites with various coating layers of CDC were obtained through a multistep coating process. The phases were studied by X-ray diffraction. The morphology and coating quality were studied by scanning electron microscopy and element mapping of energy dispersive X-ray analysis. The oxidationmore » catalytic activity, UV-shielding ability and using comfort were characterized by Rancimat test, UV-vis spectra and dynamic friction test, respectively. CDC/TT nanocomposites with low oxidation catalytic activity, high UV-shielding ability and good using comfort were finally obtained. - Graphical abstract: Through the control of surface charge of particles calcium-doped ceria/titanate composites with low oxidation catalytic activity, higher UV-shielding ability and excellent comfort was obtained by a facile layer-by-layer coating method.« less

Nanocomposites from lignin-containing cellulose nanocrystals and poly(lactic acid)

Treesearch

Liqing Wei; Umesh Agarwal; Nicole Stark; Ronald Sabo

2017-01-01

Utilizing lignin-containing cellulose nanocrystals (HLCNCs) as reinforcing agents to poly(lactic acid) (PLA) for nanocomposites was studied for the first time. The PLA/HLCNCs nanocomposites were prepared by extrusion and injecting molding. The freeze-dried HLCNCs showed micron scale agglomerates. As indicated by the water contact angle measurements, the HLCNCs were...

Ultrasonochemically conjugated metalloid/triblock copolymer nanocomposite and subsequent thin solid laminate growth for surface and interface studies.

PubMed

Veerapandian, Murugan; Yun, KyuSik

2010-09-07

Polymer and metalloid nanoparticles can be conjugated in a symphonized manner using ultrasonochemical force to obtain hybrid nanocomposites. The process is demonstrated using polymer poly(ethylene glycol) (PEG), metalloid SiO(2)@Ag, and triblock copolymer ABA. The acoustic microstreaming and cavitation force from the ultrasonics are crucial parameters that determine the harmonized PEG stabilization and ABA blending of the metalloid nanocomposites that are obtained. Surface plasmon resonance in the resulting hybrid systems are examined by UV-vis absorbance spectroscopy. The resulting PEG-stabilized SiO(2)-Ag conjugated with a triblock copolymer poly(p-dioxanone-co-caprolactone)-block-poly(ethylene oxide)-block-poly(p-dioxanone-co-caprolactone) (PPDO-co-PCL-b-PEG-b-PPDO-co-PCL/ABA) (PEG-SiO(2)@Ag/ABA) shows a red shift of 20 nm (410 nm) from its initial resonance at 390 nm (PEG-SiO(2)@Ag). Nanocomposite particles were then spin-coated on a glass substrate to obtain the growth of thin solid laminates (thickness 27 microm). Structural functionality was studied by FT-IR, (1)H NMR, and FT-Raman spectroscopy. Morphological properties were ensured from FE-SEM, HRTEM, AFM, and FIB-SEM. Identity and crystallinity of the prepared nanocomposite were confirmed by XRD analysis. A very low weight percentile loss of the fabricated nanocomposites ensures its high thermal stability. Fabricated nanocomposite laminate might have a role in coating, reinforcement, and resistance and as substrate additives for a variety of surface and interface studies. Further, the ultrasonochemical approach utilized here could also be a smart system to fabricate other heteronanostructures in a single platform.

A new approach to raising heat resistance of epoxy nanocomposites

NASA Astrophysics Data System (ADS)

Korobko, Anatoliy P.; Levakova, Irina V.; Krasheninnikov, Sergey V.

2012-07-01

A new approach to enhancing heat resistance of epoxy nanocomposites is offered. Complete exfoliation of montmorillonite particles into individual platelets (nanoparticles) is not sufficient condition for increasing the glass transition temperature of the epoxy nanocomposite. A much higher contribution to the increase in the heat resistance is ensured by grafting of epoxy molecular chains onto the surface of aluminosilicate platelets.

Roll-to-Roll Continuous Manufacturing Multifunctional Nanocomposites by Electric-Field-Assisted "Z" Direction Alignment of Graphite Flakes in Poly(dimethylsiloxane).

PubMed

Guo, Yuanhao; Chen, Yuwei; Wang, Enmin; Cakmak, Miko

2017-01-11

A roll-to-roll continuous process was developed to manufacture large-scale multifunctional poly(dimethylsiloxane) (PDMS) films embedded with thickness direction ("Z" direction) aligned graphite nanoparticles by application of electric field. The kinetics of particle "Z" alignment and chain formation was studied by tracking the real-time change of optical light transmission through film thickness direction. Benefiting from the anisotropic structure of aligned particle chains, the electrical and thermal properties of the nanocomposites were dramatically enhanced through the thickness direction as compared to those of the nanocomposites containing the same particle loading without electrical field alignment. With 5 vol % graphite loading, 250 times higher electrical conductivity, 43 times higher dielectric permittivity, and 1.5 times higher thermal conductivity was achieved in the film thickness direction after the particles were aligned under electrical field. Moreover, the aligned nanocomposites with merely 2 vol % graphite particles exhibit even higher electric conductivity and dielectric permittivity than those of the nonaligned nanocomposites at random percolation threshold (10 vol % particles), as the "electric-field-directed" percolation threshold concentration is substantially decreased using this process. As the graphite loading increases to 20 vol %, the aligned nanocomposites exhibit thermal conductivity as high as 6.05 W/m·K, which is 35 times the thermal conductivity of pure matrix. This roll-to-roll electric field continuous process provides a simple, low-cost, and commercially viable method to manufacture multifunctional nanocomposites for applications as embedded capacitor, electromagnetic (EM) shielding, and thermal interface materials.

Synthesis of photothermal nanocomposites and their application to antibacterial assays

NASA Astrophysics Data System (ADS)

Yang, Ning; Wang, Chun; Wang, Xiaoyu; Li, Lidong

2018-04-01

In this work, we report a novel gold nanorod (AuNR)-based nanocomposite that shows strong binding to bacterium and high antibacterial efficiency. The AuNRs were used as a photothermal material to transform near-infrared radiation (NIR) into heat. We selected poly (acrylic acid) to modify the surface of the AuNRs based on a simple self-assembly method. After conjugation of the bacterium-binding molecule vancomycin, the nanocomposites were capable of efficiently gathering on the cell walls of bacteria. The nanocomposites exhibited a high bacterial inhibition capability owing to NIR-induced heat generation in situ. Therefore, the prepared photothermal nanocomposites show great potential for use in antibacterial assays.

Manufacturing of Nanocomposite Carbon Fibers and Composite Cylinders

NASA Technical Reports Server (NTRS)

Tan, Seng; Zhou, Jian-guo

2013-01-01

Pitch-based nanocomposite carbon fibers were prepared with various percentages of carbon nanofibers (CNFs), and the fibers were used for manufacturing composite structures. Experimental results show that these nanocomposite carbon fibers exhibit improved structural and electrical conductivity properties as compared to unreinforced carbon fibers. Composite panels fabricated from these nanocomposite carbon fibers and an epoxy system also show the same properties transformed from the fibers. Single-fiber testing per ASTM C1557 standard indicates that the nanocomposite carbon fiber has a tensile modulus of 110% higher, and a tensile strength 17.7% times higher, than the conventional carbon fiber manufactured from pitch. Also, the electrical resistance of the carbon fiber carbonized at 900 C was reduced from 4.8 to 2.2 ohm/cm. The manufacturing of the nanocomposite carbon fiber was based on an extrusion, non-solvent process. The precursor fibers were then carbonized and graphitized. The resultant fibers are continuous.

Bismuth oxyfluoride @ CMK-3 nanocomposite as cathode for lithium ion batteries

NASA Astrophysics Data System (ADS)

Ni, Dan; Sun, Wang; Xie, Liqiang; Fan, Qinghua; Wang, Zhenhua; Sun, Kening

2018-01-01

Bismuth oxyfluoride impregnated CMK-3 nanocomposite is synthesized by a facile nanocasting approach. Mesoporous carbon CMK-3 can suppress the aggregation and growth of bismuth oxyfluoride particles and offer rapid electron and Li ion passageways. Bismuth oxyfluoride nanoparticles are embedded in the mesoporous channels with particle size less than 20 nm. The bismuth oxyfluoride@CMK-3 nanocomposite maintains 148 mA h g-1 after 40 cycles with the capacity from both the bismuth oxyfluoride and the functional groups on the mesoporous carbon. The hybrid with confined bismuth oxyfluoride nanoparticles, conductive carbon network, and oxygen functional groups on the carbon matrix exhibits higher capacity and cycling stability than bulk bismuth oxyfluoride particles when used as lithium ion batteries cathode.

Investigation of Thermal Properties of High-Density Polyethylene/Aluminum Nanocomposites by Photothermal Infrared Radiometry

NASA Astrophysics Data System (ADS)

Koca, H. D.; Evgin, T.; Horny, N.; Chirtoc, M.; Turgut, A.; Tavman, I. H.

2017-12-01

In this study, thermal properties of high-density polyethylene (HDPE) filled with nanosized Al particles (80 nm) were investigated. Samples were prepared using melt mixing method up to filler volume fraction of 29 %, followed by compression molding. By using modulated photothermal radiometry (PTR) technique, thermal diffusivity and thermal effusivity were obtained. The effective thermal conductivity of nanocomposites was calculated directly from PTR measurements and from the measurements of density, specific heat capacity (by differential scanning calorimetry) and thermal diffusivity (obtained from PTR signal amplitude and phase). It is concluded that the thermal conductivity of HDPE composites increases with increasing Al fraction and the highest effective thermal conductivity enhancement of 205 % is achieved at a filler volume fraction of 29 %. The obtained results were compared with the theoretical models and experimental data given in the literature. The results demonstrate that Agari and Uno, and Cheng and Vachon models can predict well the thermal conductivity of HDPE/Al nanocomposites in the whole range of Al fractions.

Synthesis and characterization of hybrid nanocomposites as highly-efficient conducting CH4 gas sensor.

PubMed

Aldalbahi, Ali; Feng, Peter; Alhokbany, Norah; Al-Farraj, Eida; Alshehri, Saad M; Ahamad, Tansir

2017-02-15

Functionalized (MWCNTs-COOH), non-functionalized multiwalled carbon nanotubes (MWCNTs) and polyaniline (PANI) based conducting nanocomposites (PANI/polymer/MWCNTs and PANI/polymer/MWCNTs-COOH) have been prepared in polymer matrix. The prepared nanocomposites were characterized via FTIR, TGA, Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was observed that the prepared conducting nanocomposites show excellent sensing performances toward CH 4 at room temperature and both the response and recovery time were recorded at around 5s, respectively, at the room. The PANI/polymer/MWCNTs based detector had quicker/shorter response time (<1s), as well as higher sensitivity (3.1%) than that of the PANI/polymer/MWCNTs-COOH based detector. This was attributed to nonconductive -COOH that results in a poor sensitivity of PANI/polymer/MWCNTs-COOH-based prototype. The PANI/polymer/MWCNTs-COOH nanocomposites show almost 10 time higher sensitivity at higher temperature (60°C) than that at room temperature. Copyright © 2016. Published by Elsevier B.V.

Ceramic Nanocomposites from Tailor-Made Preceramic Polymers

PubMed Central

Mera, Gabriela; Gallei, Markus; Bernard, Samuel; Ionescu, Emanuel

2015-01-01

The present Review addresses current developments related to polymer-derived ceramic nanocomposites (PDC-NCs). Different classes of preceramic polymers are briefly introduced and their conversion into ceramic materials with adjustable phase compositions and microstructures is presented. Emphasis is set on discussing the intimate relationship between the chemistry and structural architecture of the precursor and the structural features and properties of the resulting ceramic nanocomposites. Various structural and functional properties of silicon-containing ceramic nanocomposites as well as different preparative strategies to achieve nano-scaled PDC-NC-based ordered structures are highlighted, based on selected ceramic nanocomposite systems. Furthermore, prospective applications of the PDC-NCs such as high-temperature stable materials for thermal protection systems, membranes for hot gas separation purposes, materials for heterogeneous catalysis, nano-confinement materials for hydrogen storage applications as well as anode materials for secondary ion batteries are introduced and discussed in detail. PMID:28347023

PREPARATION OF HIGH-DENSITY, COMPACTIBLE THORIUM OXIDE PARTICLES

DOEpatents

McCorkle, K.H.; Kleinsteuber, A.T.; Schilling, C.E.; Dean, O.C.

1962-05-22

A method is given for preparing millimeter-size, highdensity thorium oxide particles suitable for fabrication into nuclear reactor feel elements by means of vibratory compaction. A thorium oxide gel containing 3.7 to 7 weight per cent residual volatile nitrate and water is prepared by drying a thorium oxide sol. The gel is then slowly heated to a temperature of about 450DEC, and the resulting gel fragments are calcined. The starting sol is prepared by repeated dispersion of oxalate-source thorium oxide in a nitrate system or by dispersion of steam-denitrated thorium oxide in water. (AEC)

Electrical, Elastic, and Piezoresistive Properties of Nanocomposites of Poly(dimethylsiloxane) and Poly(phenylmethylsiloxane)-Functionalized Graphene Nanoplatelets

NASA Astrophysics Data System (ADS)

Zhang, Biao; Li, Buyin; Jiang, Shenglin

2017-10-01

High-performance piezoresistive materials can detect pressures in the finger-sensing regime (0 kPa to 100 kPa). Piezoresistive nanocomposites of poly(phenylmethylsiloxane) (PPMS)-functionalized graphene nanoplatelets (P-GNPs) as conductive filler and polydimethylsiloxane (PDMS) as polymer matrix have been prepared and their electrical, elastic, and piezoresistive properties investigated. GNPs were π-π stacked with PPMS by noncovalent functionalization, and P-GNPs/PDMS nanocomposites were prepared by solution casting. The results showed that P-GNPs with sandwiched nanostructures (PPMS/GNPs/PPMS) exhibited improved dispersibility and compatibility in the PDMS matrix. Compared with GNPs/PDMS nanocomposites, low percolation threshold (2.96 vol.%) was obtained for the P-GNPs/PDMS nanocomposites. P-GNPs/PDMS nanocomposite with 3.00 vol.% P-GNPs showed remarkable negative piezoresistivity with high sensitivity of -105.22 × 10-3 kPa-1 (0 kPa to 10 kPa), low Young's modulus of 408.26 kPa, and high electrical conductivity of 1.28 × 10-6 S/m. These results demonstrate a simple and low-cost method for preparation of high-performance nanocomposites and facilitate wide application of such piezoresistive materials, especially in cheap and flexible tactile sensors.

Preparation and characterization of copper-graphite composites by electrical explosion of wire in liquid.

PubMed

Bien, T N; Gul, W H; Bac, L H; Kim, J C

2014-11-01

Copper-graphite nanocomposites containing 5 vol.% graphite were prepared by a powder metallurgy route using an electrical wire explosion (EEW) in liquid method and spark plasma sintering (SPS) process. Graphite rods with a 0.3 mm diameter and copper wire with a 0.2 mm diameter were used as raw materials for EEWin liquid. To compare, a pure copper and copper-graphite mixture was also prepared. The fabricated graphite was in the form of a nanosheet, onto which copper particles were coated. Sintering was performed at 900 degrees C at a heating rate of 30 degrees C/min for 10 min and under a pressure of 70 MPa. The density of the sintered composite samples was measured by the Archimedes method. A wear test was performed by a ball-on-disc tribometer under dry conditions at room temperature in air. The presence of graphite effectively reduced the wear of composites. The copper-graphite nanocomposites prepared by EEW had lower wear rates than pure copper material and simple mixed copper-graphite.

Graphene oxide - Polyvinyl alcohol nanocomposite based electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

Pawar, Pranav Bhagwan; Shukla, Shobha; Saxena, Sumit

2016-07-01

Supercapacitors are high capacitive energy storage devices and find applications where rapid bursts of power are required. Thus materials offering high specific capacitance are of fundamental interest in development of these electrochemical devices. Graphene oxide based nanocomposites are mechanically robust and have interesting electronic properties. These form potential electrode materials efficient for charge storage in supercapacitors. In this perspective, we investigate low cost graphene oxide based nanocomposites as electrode material for supercapacitor. Nanocomposites of graphene oxide and polyvinyl alcohol were synthesized in solution phase by integrating graphene oxide as filler in polyvinyl alcohol matrix. Structural and optical characterizations suggest the formation of graphene oxide and polyvinyl alcohol nanocomposites. These nanocomposites were found to have high specific capacitance, were cyclable, ecofriendly and economical. Our studies suggest that nanocomposites prepared by adding 0.5% wt/wt of graphene oxide in polyvinyl alcohol can be used an efficient electrode material for supercapacitors.

Spherical boron nitride particles and method for preparing them

DOEpatents

Phillips, Jonathan; Gleiman, Seth S.; Chen, Chun-Ku

2003-11-25

Spherical and polyhedral particles of boron nitride and method of preparing them. Spherical and polyhedral particles of boron nitride are produced from precursor particles of hexagonal phase boron nitride suspended in an aerosol gas. The aerosol is directed to a microwave plasma torch. The torch generates plasma at atmospheric pressure that includes nitrogen atoms. The presence of nitrogen atoms is critical in allowing boron nitride to melt at atmospheric pressure while avoiding or at least minimizing decomposition. The plasma includes a plasma hot zone, which is a portion of the plasma that has a temperature sufficiently high to melt hexagonal phase boron nitride. In the hot zone, the precursor particles melt to form molten particles that acquire spherical and polyhedral shapes. These molten particles exit the hot zone, cool, and solidify to form solid particles of boron nitride with spherical and polyhedral shapes. The molten particles can also collide and join to form larger molten particles that lead to larger spherical and polyhedral particles.

Synthesis of Aluminum-Aluminum Nitride Nanocomposites by a Gas-Liquid Reaction II. Microstructure and Mechanical Properties

NASA Astrophysics Data System (ADS)

Borgonovo, Cecilia; Makhlouf, Makhlouf M.

2016-04-01

In situ fabrication of the reinforcing particles in the metal matrix is an answer to many of the challenges encountered in manufacturing aluminum matrix nanocomposites. In this method, the nanoparticles are formed directly within the melt by means of a chemical reaction between a specially designed aluminum alloy and a gas. In this publication, we describe a process for synthesizing aluminum-aluminum nitride nanocomposites by reacting a nitrogen-containing gas with a molten aluminum-lithium alloy. We quantify the effect of the process parameters on the average particle size and particle distribution, as well as on the tendency of the particles to cluster in the alloy matrix, is quantified. Also in this publication, we present the measured room temperature and elevated temperature tensile properties of the nanocomposite material as well as its measured room temperature impact toughness.

Novel nanocomposite coating for dental implant applications in vitro and in vivo evaluation.

PubMed

Mehdikhani-Nahrkhalaji, M; Fathi, M H; Mortazavi, V; Mousavi, S B; Hashemi-Beni, B; Razavi, S M

2012-02-01

This study aimed at preparation and in vitro and in vivo evaluation of novel bioactive, biodegradable, and antibacterial nanocomposite coating for the improvement of stem cells attachment and antibacterial activity as a candidate for dental implant applications. Poly (lactide-co-glycolide)/bioactive glass/hydroxyapatite (PBGHA) nanocomposite coating was prepared via solvent casting process. The nanoparticle amounts of 10, 15, and 20 weight percent (wt%) were chosen in order to determine the optimum amount of nanoparticles suitable for preparing an uniform coating. Bioactivity and degradation of the coating with an optimum amount of nanoparticles were evaluated by immersing the prepared samples in simulated body fluid and phosphate buffer saline (PBS), respectively. The effect of nanocomposite coating on the attachment and viability of human adipose-derived stem cells (hASCs) was investigated. Kirschner wires (K-wires) of stainless steel were coated with the PBGHA nanocomposite coating, and mechanical stability of the coating was studied during intramedullary implantation into rabbit tibiae. The results showed that using 10 wt% nanoparticles (5 wt% HA and 5 wt% BG) in the nanocomposite could provide the desired uniform coating. The study of in vitro bioactivity showed rapid formation of bone-like apatite on the PBGHA coating. It was degraded considerably after about 60 days of immersion in PBS. The hASCs showed excellent attachment and viability on the coating. PBGHA coating remained stable on the K-wires with a minimum of 96% of the original coating mass. It was concluded that PBGHA nanocomposite coating provides an ideal surface for the stem cells attachment and viability. In addition, it could induce antibacterial activity, simultaneously.

An extended micromechanics method for probing interphase properties in polymer nanocomposites [An extended micromechanics method for overlapping geometries with application to polymer nanocomposites

DOE PAGES

Liu, Zeliang; Moore, John A.; Liu, Wing Kam

2016-05-03

Inclusions comprised on filler particles and interphase regions commonly form complex morphologies in polymer nanocomposites. Addressing these morphologies as systems of overlapping simple shapes allows for the study of dilute particles, clustered particles, and interacting interphases all in one general modeling framework. To account for the material properties in these overlapping geometries, weighted-mean and additive overlapping conditions are introduced and the corresponding inclusion-wise integral equations are formulated. An extended micromechanics method based on these overlapping conditions for linear elastic and viscoelastic heterogeneous material is then developed. An important feature of the proposed approach is that the effect of both themore » geometric overlapping (clustered particles) and physical overlapping (interacting interphases) on the effective properties can be distinguished. Lastly, we apply the extended micromechanics method to a viscoelastic polymer nanocomposite with interphase regions, and estimate the properties and thickness of the interphase region based on experimental data for carbon-black filled styrene butadiene rubbers.« less

An extended micromechanics method for probing interphase properties in polymer nanocomposites [An extended micromechanics method for overlapping geometries with application to polymer nanocomposites

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

Liu, Zeliang; Moore, John A.; Liu, Wing Kam

Inclusions comprised on filler particles and interphase regions commonly form complex morphologies in polymer nanocomposites. Addressing these morphologies as systems of overlapping simple shapes allows for the study of dilute particles, clustered particles, and interacting interphases all in one general modeling framework. To account for the material properties in these overlapping geometries, weighted-mean and additive overlapping conditions are introduced and the corresponding inclusion-wise integral equations are formulated. An extended micromechanics method based on these overlapping conditions for linear elastic and viscoelastic heterogeneous material is then developed. An important feature of the proposed approach is that the effect of both themore » geometric overlapping (clustered particles) and physical overlapping (interacting interphases) on the effective properties can be distinguished. Lastly, we apply the extended micromechanics method to a viscoelastic polymer nanocomposite with interphase regions, and estimate the properties and thickness of the interphase region based on experimental data for carbon-black filled styrene butadiene rubbers.« less

Graphene oxide-silica nanohybrids as fillers for PA6 based nanocomposites

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

Maio, A.; Fucarino, R.; Khatibi, R.

Graphene oxide (GO) was prepared by oxidation of graphite flakes by a mixture of H{sub 2}SO{sub 4}/H{sub 3}PO{sub 4} and KMnO{sub 4} based on Marcano's method. Two different masterbatches containing GO (33.3%) and polyamide-6 (PA6) (66.7%) were prepared both via solvent casting in formic acid and by melt mixing in a mini-extruder (Haake). The two masterbatches were then used to prepare PA6-based nanocomposites with a content of 2% in GO. For comparison, a nanocomposite by direct mixing of PA6 and GO (2%) and PA6/graphite nanocomposites were prepared, too. The oxidation of graphite into GO was assessed by X-ray diffraction (XRD),more » Micro-Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) analyses. All these techniques demonstrated the effectiveness of the graphite modification, since the results put into evidence that, after the acid treatment, interlayer distance, oxygen content and defects increased. SEM micrographs carried out on the nanocomposites, showed GO layers totally surrounded by polyamide-6, this feature is likely due to the strong interaction between the hydrophilic moieties located both on GO and on PA6. On the contrary, no interactions were observed when graphite was used as filler. Mechanical characterization, carried out by tensile and dynamic-mechanical tests, marked an improvement of the mechanical properties observed. Photoluminescence and EPR measurements were carried out onto nanoparticles and nanocomposites to study the nature of the interactions and to assess the possibility to use this class of materials as semiconductors or optical sensors.« less

Effects of SiO2 nano-particles on tribological and mechanical properties of aluminum matrix composites by different dispersion methods

NASA Astrophysics Data System (ADS)

Azadi, Mahboobeh; Zolfaghari, Mehrdad; Rezanezhad, Saeid; Azadi, Mohammad

2018-05-01

This study has been presented with mechanical properties of aluminum matrix composites, reinforced by SiO2 nano-particles. The stir casting method was employed to produce various aluminum matrix composites. Different composites by varying the SiO2 nano-particle content (including 0.5 and 1 weight percents) and two dispersion methods (including ball-milling and pre-heating) were made. Then, the density, the hardness, the compression strength, the wear resistance and the microstructure of nano-composites have been studied in this research. Besides, the distribution of nano-particles in the aluminum matrix for all composites has been also evaluated by the field emission scanning electron microscopy (FESEM). Obtained results showed that the density, the elongation and the ultimate compressive strength of various nano-composites decreased by the presence of SiO2 nano-particles; however, the hardness, the wear resistance, the yield strength and the elastic modulus of composites increased by auditioning of nano-particles to the aluminum alloy. FESEM images indicated better wetting of the SiO2 reinforcement in the aluminum matrix, prepared by the pre-heating dispersion method, comparing to ball-milling. When SiO2 nano-particles were added to the aluminum alloy, the morphology of the Si phase and intermetallic phases changed, which enhanced mechanical properties. In addition, the wear mechanism plus the friction coefficient value were changed for various nano-composites with respect to the aluminum alloy.

Preparation of graphene-ZrO2 nanocomposites by heat treatment and photocatalytic degradation of organic dyes.

PubMed

Cho, Bum Hwi; Ko, Weon Bae

2013-11-01

ZrO2 nanoparticles were synthesized by combining a solution containing zinconyl chloride in distilled water with a NH4OH solution under microwave irradiation. Graphene and ZrO2 nanocomposites were synthesized in an electric furnace at 700 degrees C for 2 hours. The heated graphene-ZrO2 nanocomposites were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. In addition, UV-vis spectrophotometry was used to evaluate the heated graphene-ZrO2 nanocomposites as a catalyst in the photocatalytic degradation of organic dyes. The photocatalytic effect of the heated graphene-ZrO2 nanocomposites was compared with that of unheated graphene nanoparticles, heated graphene nanoparticles, and unheated graphene-ZrO2 nanocomposites in organic dyes (methylene blue, methyl orange, and rhodamine B) under ultraviolet light at 254 nm.

Temperature-dependent phase transition and comparative investigation on enhanced magnetic and optical properties between sillenite and perovskite bismuth ferrite-rGO nanocomposites

NASA Astrophysics Data System (ADS)

Jalil, M. A.; Chowdhury, Sayeed Shafayet; Alam Sakib, Mashnoon; Enamul Hoque Yousuf, S. M.; Khan Ashik, Emran; Firoz, Shakhawat H.; Basith, M. A.

2017-08-01

The manuscript reports the synthesis as well as a comparative investigation of the structural, magnetic, and optical properties between sillenite and perovskite type bismuth ferrite-reduced graphene oxide nanocomposites. Graphite oxide is prepared using the modified Hummers' method, followed by hydrothermal synthesis of bismuth ferrite-reduced graphene oxide nanocomposites at different reaction temperatures. The X-ray diffraction measurements confirm the formation of perovskite type BiFeO3-rGO nanocomposites at a reaction temperature of 200 °C. This is the lowest temperature to obtain perovskite type BiFeO3-rGO nanocomposites under the reaction procedure adopted, however, a structural transition to sillenite type Bi25FeO40-rGO is observed at 180 °C. The FESEM images demonstrate that the particle size of the perovskite nanocomposite is 25-60 nm, and for the sillenite phase nanocomposite it is 10-30 nm. The as-synthesized nanocomposites exhibit significantly enhanced saturation magnetization over pure BiFeO3 nanoparticles, with the sillenite Bi25FeO40-rGO nanocomposite having higher saturation magnetization than perovskite BiFeO3-rGO. The optical characteristics of the as-synthesized nanocomposites demonstrate considerably higher absorbance in the visible range with significantly lower band gap in comparison to undoped BiFeO3. Again, the sillenite Bi25FeO40-rGO nanocomposite is shown to have a lower band gap compared to the perovskite counterpart. Our investigation provides a means of selective phase formation as desired between sillenite Bi25FeO40-rGO and perovskite BiFeO3-rGO by controlling the hydrothermal reaction temperature. The outcome of our investigation suggests that the formation of nanocomposite of sillenite bismuth ferrite with reduced graphene oxide is promising to improve the magnetic and optical properties for potential technological applications.

Effect of reinforcing particle type on morphology and age-hardening behavior of Al–4.5 wt.% Cu based nanocomposites synthesized through mechanical milling

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

Mostaed, A., E-mail: alimostaed@yahoo.com; Saghafian, H.; Mostaed, E.

2013-02-15

The effects of reinforcing particle type (SiC and TiC) on morphology and precipitation hardening behavior of Al–4.5%Cu based nanocomposites synthesized via mechanical milling were investigated in the current work. In order to study the microstructure and morphology of mechanically milled powder, X-ray diffraction technique, scanning electron microscopy and high resolution transmission electron microscopy were utilized. Results revealed that at the early stages of mechanical milling, when reinforcing particles are polycrystal, the alloying process is enhanced more in the case of using the TiC particles as reinforcement. But, at the final stages of mechanical milling, when reinforcing particles are single crystal,more » the alloying process is enhanced more in the case of using the SiC ones. Transmission electron microscopy results demonstrated that Al–4.5 wt.%Cu based nanocomposite powders were synthesized and confirmed that the mutual diffusion of aluminum and copper occurs through the interfacial plane of (200). The hardness results showed that not only does introducing 4 vol.% of reinforcing particles (SiC or TiC) considerably decrease the porosity of the bulk composite samples, but also it approximately doubles the hardness of Al–4.5 wt.%Cu alloy (53.4 HB). Finally, apart from TEM and scanning electron microscopy observation which are localized, a decline in hardness in the TiC and SiC contained samples, respectively, after 1.5 and 2 h aging time at 473 K proves the fact that the size of SiC particles is smaller than the size of the TiC ones. - Highlights: ► HRTEM results show mutual diffusion of Al and Cu occurs through the (200) planes. ► TiC particles enhance alloying process more than the SiC ones at the early stages of MM. ► SiC particles enhance alloying process more than the TiC ones at the final stages of MM.« less

Ziegler-Natta Catalyst Based on MgCl₂/Clay/ID/TiCl₄ for the Synthesis of Spherical Particles of Polypropylene Nanocomposites.

PubMed

Cardoso, Renata da Silva; Oliveira, Jaqueline da Silva; Ramis, Luciana Bortolin; Marques, Maria de Fátima V

2018-07-01

In the present work, we have designed MgCl2/clay/internal donor (ID)/TiCl4 based bisupported Ziegler-Natta catalysts containing varying amounts of organoclay (montmorillonite) in order to synthesize spherical particles of polypropylene/clay nanocomposites (PCN). The organoclay was introduced into the catalyst support formulation and PCN was obtained using the in situ polymerization technique. Decreasing the reaction time, it was possible to obtain nanocomposites with high concentrations of clay (masterbatches). Micrographs of SEM confirmed the spherical morphology of the catalysts. In addition, XRD patterns show that the active sites for polymerization were inserted in the clay galleries. The catalytic performance was evaluated in slurry propylene polymerization using triethylaluminium as cocatalyst and silane as external electron donor at 70 °C, 4 bar, and different reaction times. The PCNs obtained containing different clay amounts were characterized by X-ray diffraction, thermal analyses, transmission electronic microscopy, and extractables in heptane. The results revealed that the synthesized PP/clay particles were also spherical showing that the morphological control is possible even using catalysts containing high amounts of clay. The PCN presented high degradation temperature (459 °C). The XRD peak related to the clay interlamellar distance has shifted to lower angles, and TEM images confirmed the formation of exfoliated/intercalated clay on the PP matrix and absence of microparticles of clay.

Hydrothermal Synthesis and Electrochemical Properties of CoS2-Reduced Graphene Oxide Nanocomposite for Supercapacitor Application

NASA Astrophysics Data System (ADS)

Venkateshalu, Sandhya; Rangappa, Dinesh; Grace, Andrews Nirmala

A Cobalt disulfide-reduced graphene oxide (CoS2-RGO) nanocomposite was prepared by a simple hydrothermal method and the prepared nanocomposite was characterized using various techniques like XRD, SEM and FTIR. The results of these techniques indicated the uniform deposition of CoS2 nanoparticles on Graphene sheets. Further, the prepared nanocomposites were tested for its activity towards energy storage and the test results showed a specific capacitance of 28F/g in an aqueous 20% KOH electrolyte at a current density of 0.5A/g. All these materials showed highly reversible charge-discharge cycles. The overall electrochemical performance of this composite is shown to be drastically improved when compared to bare CoS2 nanoparticles. Thus with the good electrochemical properties, CoS2-RGO nanocomposites could be effectively used as an electrode material for supercapacitors.

Preparation and Characterization of Colloidal Silica Particles under Mild Conditions

ERIC Educational Resources Information Center

Neville, Frances; Zin, Azrinawati Mohd.; Jameson, Graeme J.; Wanless, Erica J.

2012-01-01

A microscale laboratory experiment for the preparation and characterization of silica particles at neutral pH and ambient temperature conditions is described. Students first employ experimental fabrication methods to make spherical submicrometer silica particles via the condensation of an alkoxysilane and polyethyleneimine, which act to catalyze…

Comparative study on the mechanical and microstructural characterisation of AA 7075 nano and hybrid nanocomposites produced by stir and squeeze casting.

PubMed

Kannan, C; Ramanujam, R

2017-07-01

In this research work, a comparative evaluation on the mechanical and microstructural characteristics of aluminium based single and hybrid reinforced nanocomposites was carried out. The manufacture of a single reinforced nanocomposite was conducted with the distribution of 2 wt.% nano alumina particles (avg. particle size 30-50 nm) in the molten aluminium alloy of grade AA 7075; while the hybrid reinforced nanocomposites were produced with of 4 wt.% silicon carbide (avg. particle size 5-10 µm) and 2 wt.%, 4 wt.% nano alumina particles. Three numbers of single reinforced nanocomposites were manufactured through stir casting with reinforcements preheated to different temperatures viz. 400 °C, 500 °C, and 600 °C. The stir cast procedure was extended to fabricate two hybrid reinforced nanocomposites with reinforcements preheated to 500 °C prior to their inclusion. A single reinforced nanocomposite was also developed by squeeze casting with a pressure of 101 MPa. Mechanical and physical properties such as density, hardness, ultimate tensile strength, and impact strength were evaluated on all the developed composites. The microstructural observation was carried out using optical and scanning electron microscopy. On comparison with base alloy, an improvement of 63.7% and 81.1% in brinell hardness was observed for single and hybrid reinforced nanocomposites respectively. About 16% higher ultimate tensile strength was noticed with the squeeze cast single reinforced nanocomposite over the stir cast.

Bio-based hyperbranched thermosetting polyurethane/triethanolamine functionalized multi-walled carbon nanotube nanocomposites as shape memory materials.

PubMed

Kalita, Hemjyoti; Karak, Niranjan

2014-07-01

Here, bio-based shape memory polymers have generated immense interest in recent times. Here, Bio-based hyperbranched polyurethane/triethanolamine functionalized multi-walled carbon nanotube (TEA-f-MWCNT) nanocomposites were prepared by in-situ pre-polymerization technique. The Fourier transform infrared spectroscopy and the transmission electron microscopic studies showed the strong interfacial adhesion and the homogeneous distribution of TEA-f-MWCNT in the polyurethane matrix. The prepared epoxy cured thermosetting nanocomposites exhibited enhanced tensile strength (6.5-34.5 MPa), scratch hardness (3.0-7.5 kg) and thermal stability (241-288 degrees C). The nanocomposites showed excellent shape fixity and shape recovery. The shape recovery time decreases (24-10 s) with the increase of TEA-f-MWCNT content in the nanocomposites. Thus the studied nanocomposites have potential to be used as advanced shape memory materials.

Ternary Au/ZnO/rGO nanocomposites electrodes for high performance electrochemical storage devices

NASA Astrophysics Data System (ADS)

Chaudhary, Manchal; Doong, Ruey-an; Kumar, Nagesh; Tseng, Tseung Yuen

2017-10-01

The combination of metal and metal oxide nanoparticles with reduced graphene oxides (rGO) is an active electrode material for electrochemical storage devices. Herein, we have, for the first time, reported the fabrication of ternary Au/ZnO/rGO nanocomposites by using a rapid and environmentally friendly microwave-assisted hydrothermal method for high performance supercapacitor applications. The ZnO/rGO provides excellent electrical conductivity and good macro/mesopore structures, which can facilitate the rapid electrons and ions transport. The Au nanoparticles with particle sizes of 7-12 nm are homogeneously distributed onto the ZnO/rGO surface to enhance the electrochemical performance by retaining the capacitance at high current density. The Au/ZnO/rGO nanocomposites, prepared with the optimized rGO amount of 100 mg exhibit a high specific capacitance of 875 and 424 F g-1 at current densities of 1 and 20 A g-1, respectively, in 2 M KOH. In addition, the energy and power densities of ternary Au/ZnO/rGO can be up to 17.6-36.5 Wh kg-1 and 0.27-5.42 kW kg-1, respectively. Results obtained in this study clearly demonstrate the excellence of ternary Au/ZnO/rGO nanocomposites as the active electrode materials for electrochemical pseudocapacitor performance and can open an avenue to fabricate metal/metal oxide/rGO nanocomposites for electrochemical storage devices with both high energy and power densities.