Science.gov

Sample records for characterizing polymer decomposition

  1. Characterization of polymer decomposition products by laser desorption mass spectrometry

    NASA Technical Reports Server (NTRS)

    Pallix, Joan B.; Lincoln, Kenneth A.; Miglionico, Charles J.; Roybal, Robert E.; Stein, Charles; Shively, Jon H.

    1993-01-01

    Laser desorption mass spectrometry has been used to characterize the ash-like substances formed on the surfaces of polymer matrix composites (PMC's) during exposure on LDEF. In an effort to minimize fragmentation, material was removed from the sample surfaces by laser desorption and desorbed neutrals were ionized by electron impact. Ions were detected in a time-of-flight mass analyzer which allows the entire mass spectrum to be collected for each laser shot. The method is ideal for these studies because only a small amount of ash is available for analysis. Three sets of samples were studied including C/polysulfone, C/polyimide and C/phenolic. Each set contains leading and trailing edge LDEF samples and their respective controls. In each case, the mass spectrum of the ash shows a number of high mass peaks which can be assigned to fragments of the associated polymer. These high mass peaks are not observed in the spectra of the control samples. In general, the results indicate that the ash is formed from decomposition of the polymer matrix.

  2. Synthesis, characterization and non-isothermal decomposition kinetic of a new galactochloralose based polymer.

    PubMed

    Kök, Gökhan; Ay, Kadir; Ay, Emriye; Doğan, Fatih; Kaya, Ismet

    2014-01-30

    A glycopolymer, poly(3-O-methacroyl-5,6-O-isopropylidene-1,2-O-(S)-trichloroethylidene-α-d-galactofuranose) (PMIPTEG) was synthesized from the sugar-carrying methacrylate monomer, 3-O-methacroyl-5,6-O-isopropylidene-1,2-O-(S)-trichloroethylidene-α-d-galactofuranose (MIPTEG) via conventional free radical polymerization with AIBN in 1,4-dioxane. The structures of glycomonomer and their polymers were confirmed by UV-vis, FT-IR, (1)H NMR, (13)C NMR, GPC, TG/DTG-DTA, DSC, and SEM techniques. SEM images showed that PMIPTEG had a straight-chain length structure. On the other hand, the thermal decomposition kinetics of polymer were investigated by means of thermogravimetric analysis in dynamic nitrogen atmosphere at different heating rates. The apparent activation energies for thermal decomposition of the PMIPTEG were calculated using the Kissinger, Kim-Park, Tang, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman methods and were found to be 100.15, 104.40, 102.0, 102.2, 103.2 and 99.6 kJ/mol, respectively. The most likely process mechanism related to the thermal decomposition stage of PMIPTEG was determined to be a Dn deceleration type in terms of master plots results.

  3. Synthesis and characterization of Mn 3O 4 nanoparticles via thermal decomposition of a new synthesized hydrogen bonded polymer

    NASA Astrophysics Data System (ADS)

    Morsali, Ahmad; Monfared, Hassan Hossieni; Morsali, Ali

    2009-12-01

    A new Mn(II) compound, [Mn(pyterpy)(H 2O)(N 3)(NO 3)] ( 1) [pyterpy = 4'-(4-pyridyl)-2,2':6',2''-terpyridine], was synthesized by the reaction of pyterpy and mixtures of manganese(II) nitrate and sodium azide using heat gradient method. The compound 1 characterized by IR spectroscopy, elemental analyses and X-ray crystallography. The crystal structure of compound 1 was determined by single-crystal X-ray diffraction. The potentially tetradentate pyterpy ligand acts as a tridentate donor. The noncoordinated pyridyl group interacts via O-H⋯N hydrogen bonds with adjacent molecules. Mn 3O 4 nanoparticles were obtained by thermolyses of compound 1 in oleic acid at 320 °C under air atmosphere. The Mn 3O 4 nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA).

  4. Characterization of Nanostructured Polymer Films

    DTIC Science & Technology

    2014-12-23

    of the film for complete polymer chain relaxation, including relaxation of surface features . The presence of intact surface globules at a substrate...AFRL-OSR-VA-TR-2015-0059 Characterization of Nanostructured Polymer Films RODNEY PRIESTLEY TRUSTEES OF PRINCETON UNIVERSITY Final Report 12/23/2014...Report 3. DATES COVERED (From - To) 06/01/2012-08/31/2014 4. TITLE AND SUBTITLE Characterization of Nanostructured Polymer Films 5a. CONTRACT

  5. Spectroscopic characterization of polymers: report

    SciTech Connect

    Koenig, J.L.

    1987-10-01

    Polymer characterization has presented major difficulties to the analytical chemist, who has had to develop techniques to cope with the challenge. Even the elementary problem of measuring molecular weight is not easy. Yet such measurements are essential, because the physical, mechanical, and flow properties depend on the length of the polymer chain. Because of the limited solubility and high viscosity of polymers, many classical techniques have been of little use or have had to be extensively modified to measure the molecular weight of polymers. Size-exclusion chromatographic techniques such as gel permeation have been developed to measure these molecular weight distributions. Special chromatographic instruments with a range of spectroscopic detectors (including infrared and laser-light scattering) have emerged commercially to aid the analytical chemist in the fundamental endeavor to measure the length of the polymer chain and its distribution. The author describes the advantages and disadvantages and disadvantages of various spectroscopic techniques.

  6. Characterization and measurement of polymer wear

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.; Aron, P. R.

    1984-01-01

    Analytical tools which characterize the polymer wear process are discussed. The devices discussed include: visual observation of polymer wear with SEM, the quantification with surface profilometry and ellipsometry, to study the chemistry with AES, XPS and SIMS, to establish interfacial polymer orientation and accordingly bonding with QUARTIR, polymer state with Raman spectroscopy and stresses that develop in polymer films using a X-ray double crystal camera technique.

  7. Characterization and measurement of polymer wear

    NASA Technical Reports Server (NTRS)

    Buckley, D. H.; Aron, P. R.

    1985-01-01

    Analytical tools which characterize the polymer wear process are discussed. The devices discussed include: visual observation of polymer wear with SEM, the quantification with surface profilometry and ellipsometry, to study the chemistry with AES, XPS and SIMS, to establish interfacial polymer orientation and accordingly bonding with QUARTIR, polymer state with Raman spectroscopy and stresses that develop in polymer films using a X-ray double crystal camera technique.

  8. A study of the process of nonisothermal decomposition of phenolformaldehyde polymers by differential thermal analysis

    SciTech Connect

    Petrova, O.M.; Fedoseev, S.D.; Komarova, T.V.

    1984-01-01

    A calculation has been made of the activation energy of the thermal decomposition of phenol-formaldehyde polymers. It has been established that for nonisothermal conditions the rate of performance of the process does not affect the effective activation energy calculated by means of Piloyan's equation.

  9. The correlation between elongation at break and thermal decomposition of aged EPDM cable polymer

    NASA Astrophysics Data System (ADS)

    Šarac, T.; Devaux, J.; Quiévy, N.; Gusarov, A.; Konstantinović, M. J.

    2017-03-01

    The effect of simultaneous thermal and gamma irradiation ageing on the mechanical and physicochemical properties of industrial EPDM was investigated. Accelerated ageing, covering a wide range of dose rates, doses and temperatures, was preformed in stagnant air on EPDM polymer samples extracted from the cables in use in the Belgian nuclear power plants. The mechanical properties, ultimate tensile stress and elongation at break, are found to exhibit the strong dependence on the dose, ageing temperature and dose rate. The thermal decomposition of aged polymer is observed to be the dose dependent when thermogravimetry test is performed under air atmosphere. No dose dependence is observed when thermal decomposition is performed under nitrogen atmosphere. The thermal decomposition rates are found to fully mimic the reduction of elongation at break for all dose rates and ageing temperatures. This effect is argued to be the result of thermal and radiation mediated oxidation degradation process.

  10. Positronium as a probe in natural polymers: decomposition in starch.

    PubMed

    Roudaut, G; Duplâtre, G

    2009-11-07

    Ortho-positronium (o-Ps) is used as a probe in positron annihilation lifetime spectroscopy (PALS) experiments, to characterise the behaviour of free volumes in natural starch samples, as a function of temperature (T). Up to about 540 K, the o-Ps intensity, I(3), remains constant at 26.2% while its lifetime, tau(3), is found to increase linearly. Both parameters undergo a decrease above this T, due to the onset of decomposition, which results in a shrinking of the sample pellets. The results indicate that the glass transition temperature should be above 501 K. Data from thermal gravimetry analysis (TGA) measurements are well described by supposing a first order process for the survival probability (p) of the starch lattice, with an activation energy, E(act) = (1.52 +/- 0.05) eV, and a frequency factor, ln(k(0), s(-1)) = 25.3 +/- 0.4. In the decomposition region, the PALS data show the unexpected correlation (tau(3n))(3) = I(3n), linking the normalised values of tau(3), tau(3n), and of I(3), I(3n). This is explained by considering that the changes in I(3) with T arise from those in the surviving volume fraction of the lattice, p, whereas the changes in tau(3) reflect the shrinking of the radius of the free volumes, the latter decreasing in proportion to p(1/3). Quantitative approaches on these bases lead to satisfactory fitting of all PALS data, yielding an activation energy, E(act) = (1.53 +/- 0.03) eV, and frequency factor, ln(k(0), s(-1)) = 25.4 +/- 0.2, in excellent agreement with the values derived from TGA.

  11. Synthesis and characterization of complex polymer architectures

    NASA Astrophysics Data System (ADS)

    Farmer, Brandon Scott

    Anionic polymerization based upon high vacuum technique has been used to synthesize different star polymers using varying linking techniques. In particular chlorosilanes, divinylbenzene, and polyhedral oligomeric silsesquioxane (POSS) chlorosilane derivatives were used in the synthesis of star polymers. These polymers, along with polymers synthesized by others, have been characterized by a range of methods in this work. A series of polyisoprene (PI) stars were synthesized from dimethylaminopropyllithium (DMAPLi) and subsequently hydrogenated to form poly (ethylene-co-propylene) (PEP) these were characterized by size exclusion chromatography (SEC) coupled with online two angle laser light scattering (TALLS). These polymers were synthesized in an attempt to make a new series of viscosity index improvers as an oil additive. The polymers were characterized by differential scanning calorimetry and thermal gravimetric analysis. A novel process for producing eight arm star polymers was explored using a Polyhedral Oligomeric Silsesquioxane (POSS) modified with chlorosilanes as the linking agent. The arms of these stars were prepared polybutadiene prepared anionically. A study of the effect of living end-groups was also explored by endcapping the living polybutadiene with a polystrylanion and the linking efficiency was monitored. These polymers were also characterized by SEC coupled with TALLS.

  12. NMR characterization of polymers: Review and update

    Technology Transfer Automated Retrieval System (TEKTRAN)

    NMR spectroscopy is a major technique for the characterization and analysis of polymers. A large number of methodologies have been developed in both the liquid and the solid state, and the literature has grown considerably (1-5). The field now covers a broad spectrum of activities, including polym...

  13. Accelerated Characterization of Polymer Properties

    SciTech Connect

    R. Wroczynski; l. Brewer; D. Buckley; M. Burrell; R. Potyrailo

    2003-07-30

    This report describes the efforts to develop a suite of microanalysis techniques that can rapidly measure a variety of polymer properties of industrial importance, including thermal, photo-oxidative, and color stability; as well as ductility, viscosity, and mechanical and antistatic properties. Additional goals of the project were to direct the development of these techniques toward simultaneous measurements of multiple polymer samples of small size in real time using non-destructive and/or parallel or rapid sequential measurements, to develop microcompounding techniques for preparing polymers with additives, and to demonstrate that samples prepared in the microcompounder could be analyzed directly or used in rapid off-line measurements. These enabling technologies are the crucial precursors to the development of high-throughput screening (HTS) methodologies for the polymer additives industry whereby the rate of development of new additives and polymer formulations can be greatly accelerated.

  14. Mathematical simulation of thermal decomposition processes in coking polymers during intense heating

    SciTech Connect

    Shlenskii, O.F.; Polyakov, A.A.

    1994-12-01

    Description of nonstationary heat transfer in heat-shielding materials based on cross-linked polymers, mathematical simulation of chemical engineering processes of treating coking and fiery coals, and designing calculations all require taking thermal destruction kinetics into account. The kinetics of chemical transformations affects the substance density change depending on the temperature, the time, the heat-release function, and other properties of materials. The traditionally accepted description of the thermal destruction kinetics of coking materials is based on formulating a set of kinetic equations, in which only chemical transformations are taken into account. However, such an approach does not necessarily agree with the obtained experimental data for the case of intense heating. The authors propose including the parameters characterizing the decrease of intermolecular interaction in a comparatively narrow temperature interval (20-40 K) into the set of kinetic equations. In the neighborhood of a certain temperature T{sub 1}, which is called the limiting temperature of thermal decomposition, a decrease in intermolecular interaction causes an increase in the rates of chemical and phase transformations. The effect of the enhancement of destruction processes has been found experimentally by the contact thermal analysis method.

  15. Characterization of Tantalum Polymer Capacitors

    NASA Technical Reports Server (NTRS)

    Spence, Penelope

    2012-01-01

    Overview Reviewed data Caution must be taken when accelerating test conditions Data not useful to establish an acceleration model Introduction of new failure mechanism skewing results Evidence of Anti-Wear-Out De-doping of polymer Decreased capacitance Increased ESR Not dielectric breakdown Needs further investigation Further investigation into tantalum polymer capacitor technology Promising acceleration model for Manufacturer A Possibility for use in high-reliability space applications with suitable voltage derating.

  16. Decomposition

    USGS Publications Warehouse

    Middleton, Beth A.

    2014-01-01

    A cornerstone of ecosystem ecology, decomposition was recognized as a fundamental process driving the exchange of energy in ecosystems by early ecologists such as Lindeman 1942 and Odum 1960). In the history of ecology, studies of decomposition were incorporated into the International Biological Program in the 1960s to compare the nature of organic matter breakdown in various ecosystem types. Such studies still have an important role in ecological studies of today. More recent refinements have brought debates on the relative role microbes, invertebrates and environment in the breakdown and release of carbon into the atmosphere, as well as how nutrient cycling, production and other ecosystem processes regulated by decomposition may shift with climate change. Therefore, this bibliography examines the primary literature related to organic matter breakdown, but it also explores topics in which decomposition plays a key supporting role including vegetation composition, latitudinal gradients, altered ecosystems, anthropogenic impacts, carbon storage, and climate change models. Knowledge of these topics is relevant to both the study of ecosystem ecology as well projections of future conditions for human societies.

  17. Polarization and Characterization of Piezoelectric Polymers

    NASA Technical Reports Server (NTRS)

    Bodiford, Hollie N.

    1995-01-01

    Piezoelectric materials exhibit an electrical response, such as voltage or charge, in reaction to a mechanical stimuli. The mechanical stimuli can be force, pressure, light, or heat. Therefore, these materials are excellent sensors for various properties. The major disadvantage of state of the art piezoelectric polymers is their lack of utility at elevated temperatures. The objective of this research is to study the feasibility of inducing piezoelectricity in high performance polymer systems. The three aspects of the research include experimental poling, characterization of the capacitance, and demonstration of the use of a piezoelectric polymer as a speaker.

  18. Synthetic, characterization and decomposition studies of indium sulfide precursors

    SciTech Connect

    Schluter, R.D.; Luten, H.A.; Rees, W.S. Jr.

    1996-12-31

    The synthesis, characterization and decomposition of several indium thiolates containing the bulky substituted aryl ligand 2,4,6-i-Pr{sub 3}C{sub 6}H{sub 2} (Ar{prime}) or the internally chelating ligands 2-CH{sub 3}O, 5-CH{sub 3}C{sub 6}H{sub 3} (Ar{double_prime}) and o-C{sub 6}H{sub 4}CH{sub 2}N(CH{sub 3}){sub 2} (Ar{prime}{double_prime}) are described. Two synthetic methods have been utilized: metathesis reactions between lithium thiolates and the appropriate metal halides and the addition of elemental metal to diaryl disulfides. The thermal decomposition of each indium precursor results in the formation of In{sub 2}S{sub 3}, based on thermogravimetric data. The homoleptic compound In(SAr{prime}){sub 3} can be isolated as a yellow oil. This liquid precursor has been derivatized by the reversible formation of acetonitrile and tetrahydroduran adducts. Although, the molecule exists as a monomer in both adducts, the coordination number of the metal and the orientation of the ligands are markedly different. The internally chelating In(SAr{double_prime}){sub 3} and In(SAr{prime}{double_prime}){sub 3} adopt contrasting dimeric and monomeric structures respectively.

  19. Nonthermal decomposition of C60 polymers induced by tunneling electron injection

    NASA Astrophysics Data System (ADS)

    Nakamura, Yoshiaki; Kagawa, Fumitaka; Kasai, Koichi; Mera, Yutaka; Maeda, Koji

    2004-11-01

    Scanning tunneling microscopic (STM) studies of C60 films deposited on highly oriented pyrolytic graphite substrates revealed that the electron injection from the STM tip induces the decomposition (isomerization) of the C60 molecules that have been polymerized also by the electron injection into the films. Both reaction rates were characterized by a linear dependence on the injected tunneling current and a common threshold around 2 V in the sample bias dependence. We discuss two nonthermal mechanisms for the polymerization and decomposition reactions: electronic excitation mechanism by Auger decay and a hypothetical ionic reaction model.

  20. Mercer's spectral decomposition for the characterization of thermal parameters

    NASA Astrophysics Data System (ADS)

    Ahusborde, E.; Azaïez, M.; Belgacem, F. Ben; Palomo Del Barrio, E.

    2015-08-01

    We investigate a tractable Singular Value Decomposition (SVD) method used in thermography for the characterization of thermal parameters. The inverse problem to solve is based on the model of transient heat transfer. The most significant advantage is the transformation of the dynamic identification problem into a steady identification equation. The time dependence is accounted for by the SVD in a performing way. We lay down a mathematical foundation well fitted to this approach, which relies on the spectral expansion of Mercer kernels. This enables us to shed more light on most of its important features. Given its potentialities, the analysis we propose here might help users understanding the way the SVD algorithm, or the TSVD, its truncated version, operate in the thermal parameters estimation and why it is relevant and attractive. When useful, the study is complemented by some analytical and numerical illustrations realized within MATLAB's code.

  1. The mechanisms for desensitization effect of synthetic polymers on BCHMX: Physical models and decomposition pathways.

    PubMed

    Yan, Qi-Long; Zeman, Svatopluk; Zhang, Xiao-Hong; Málek, Jiří; Xie, Wu-Xi

    2015-08-30

    The project involves determination of the activation energies and physical models for thermolysis of BCHMX and its PBXs. The initial decomposition pathways were also proposed on the basis of molecular dynamic simulation. The goal is to find the mutual relationships among the physical models, decomposition pathways, and the impact sensitivities for BCHMX and its PBXs. It has been shown that the physical model of the first step of BCHMX thermolysis is close to first order and the second step is governed by a first order autocatalytic model, which turns to "2D or 3D Nucleation and Growth" models under the effect of polymeric binders probably due to their hindrances on topochemical reaction of BCHMX. Simulation results show that the scission of N-NO2 is the initial step for BCHMX pyrolysis, followed by HONO and HNO eliminations, where the latter is due to nitro-nitrite rearrangement. Under the effect of hydrocarbon polymers, the HONO/HON elimination and collapse of ring structure of BCHMX occur earlier without changing the time for N-NO2 scission, which might be the reason why those polymers have little effect on the thermal stability of BCHMX, while they could make it decompose almost in a single complex step.

  2. Synthesis, crystal structure and catalytic effect on thermal decomposition of RDX and AP: An energetic coordination polymer [Pb2(C5H3N5O5)2(NMP)·NMP]n

    NASA Astrophysics Data System (ADS)

    Liu, Jin-jian; Liu, Zu-Liang; Cheng, Jian; Fang, Dong

    2013-04-01

    An energetic lead(II) coordination polymer based on the ligand ANPyO has been synthesized and its crystal structure has been got. The polymer was characterized by FT-IR spectroscopy, elemental analysis, DSC and TG-DTG technologies. Thermal analysis shows that there are one endothermic process and two exothermic decomposition stages in the temperature range of 50-600 °C with final residues 57.09%. The non-isothermal kinetic has also been studied on the main exothermic decomposition using the Kissinger's and Ozawa-Doyle's methods, the apparent activation energy is calculated as 195.2 KJ/mol. Furthermore, DSC measurements show that the polymer has significant catalytic effect on the thermal decomposition of ammonium perchlorate.

  3. Thermochemical characterization of polymers for improved fire safety

    NASA Technical Reports Server (NTRS)

    Lerner, N. R.

    1977-01-01

    Apparatus has been constructed for studying the thermal decomposition of polymers as a function of temperature. Such data is needed to evaluate the toxic threat presented by polymeric materials under fire conditions such as the smoldering fire of the type that occurs in closed areas such as coat closets in which anaerobic decomposition of polymers occurs. The apparatus allows the products of thermal decomposition to be collected and analyzed by infrared spectrometry and mass spectrometry. Data obtained from dog hair, an aromatic polyamide, polyphenylene sulfide, and polybenzimidazole are presented. It was found that significant amounts of toxic gas were evolved from dog hair at temperatures as low as 250 C, while temperatures in excess of 500 C were necessary in order for the evolution of toxic gas from the aromatic polymers to become significant.

  4. Preparation and characterization of gradient polymer films

    SciTech Connect

    Smith, S.C.

    1987-01-01

    Gradient polymers are multicomponent polymers whose chemical constitution varies with depth in the sample. Although these polymers may possess unique mechanical, optical, and barrier properties they remain relatively unexplored. This work is a study of the preparation of gradient polymers by sequential exposure of films to a diffusing monomer followed by electron beam irradiation. Initial experiments involved immersion of poly(vinyl chloride) (PVC) films in styrene or n-butyl methacrylate (BMA) for various time periods followed by irradiation with 1 or 10 megarads of accelerated electrons. A significant amount of poly(n-butyl methacrylate) (PBMA) formed in PVC/BMA systems, but little polystyrene could be found in the PVC/styrene films. A second set of experiments involved immersion of PVC and polyethylene (PE) films in BMA for 20, 40, 60, and 720 minutes followed by irradiation with 10 megarads of electrons. These films were then characterized using optical microscopy, quantitative transmission Fourier transform infrared spectroscopy (FTIR), and a depth profiling procedure based on quantitative attenuated total reflection (ATR) FTIR. It was concluded that the mechanism of PBMA formation in the polyethylene films was a result of events immediately following irradiation. Atmospheric oxygen diffusing into irradiated films trapped free radicals at the film surfaces. This was followed by storage in an evacuated desiccator where unintentional exposure to BMA vapor took place. This BMA reacted with free radicals that remained within the film cores, polymerizing to PBMA.

  5. Quantum efficiency of PAG decomposition in different polymer matrices at advanced lithographic wavelengths

    NASA Astrophysics Data System (ADS)

    Fedynyshyn, Theodore H.; Sinta, Roger F.; Mowers, William A.; Cabral, Alberto

    2003-06-01

    The Dill ABC parameters for optical resists are typically determined by measuring the change in the intensity of transmitted light at the wavelength of interest as a function of incident energy. The effectiveness of the experiment rests with the fact that the resist optical properties change with exposure and that the optical properties are directly related to the concentration of PAG compound. These conditions are not typically satisfied in CA resists and thus C is unobtainable by this method. FT-IR spectroscopy can directly measure changes in the photoactive species by isolating and measuring absorbance peaks unique to the photoactive species. We employed the ProABC software, specially modified to allow FT-IR absorbance input, to extract ABS parameters through a best fit of the lithography model to experimental data. The quantum efficiency of PAG decomposition at 157-, 193-, and 248-nm was determined for four diazomethane type PAGs in four different polymer matrices. It was found that both the Dill C parameter and the quantum efficiency for all PAGs increased as wavelength decreased, but that the magnitude of the increase was strongly dependent on the polymer matrix.

  6. Design, synthesis, characterization and study of novel conjugated polymers

    SciTech Connect

    Chen, Wu

    1997-06-24

    After introducing the subject of conjugated polymers, the thesis has three sections each containing a literature survey, results and discussion, conclusions, and experimental methods on the following: synthesis, characterization of electroluminescent polymers containing conjugated aryl, olefinic, thiophene and acetylenic units and their studies for use in light-emitting diodes; synthesis, characterization and study of conjugated polymers containing silole unit in the main chain; and synthesis, characterization and study of silicon-bridged and butadiene-linked polythiophenes.

  7. Electrochemical characterization of aminated acrylic conducting polymer

    SciTech Connect

    Rashid, Norma Mohammad; Heng, Lee Yook; Ling, Tan Ling

    2015-09-25

    New attempt has been made to synthesize aminated acrylic conducting polymer (AACP) using precursor of phenylvinylsulfoxide (PVS). The process was conducted via the integration of microemulsion and photopolymerization techniques. It has been utilized for covalent immobilization of amino groups by the adding of N-achryiloxisuccinimide (NAS). Thermal eliminating of benzene sulfenic acids from PVS has been done at 250 °C to form electroactive polyacetylene (PA) segment. Characterization of AACP has been conducted using fourier transform infrared (FTIR), scanning electron microscopy (SEM) and linear sweep cyclic voltammetry (CV). A range of 0.3-1.25μm particle size obtained from SEM characterization. A quasi-reversible system performed as shown in electrochemical study.

  8. Characterization of Hybrid CNT Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Grimsley, Brian W.; Cano, Roberto J.; Kinney, Megan C.; Pressley, James; Sauti, Godfrey; Czabaj, Michael W.; Kim, Jae-Woo; Siochi, Emilie J.

    2015-01-01

    Carbon nanotubes (CNTs) have been studied extensively since their discovery and demonstrated at the nanoscale superior mechanical, electrical and thermal properties in comparison to micro and macro scale properties of conventional engineering materials. This combination of properties suggests their potential to enhance multi-functionality of composites in regions of primary structures on aerospace vehicles where lightweight materials with improved thermal and electrical conductivity are desirable. In this study, hybrid multifunctional polymer matrix composites were fabricated by interleaving layers of CNT sheets into Hexcel® IM7/8552 prepreg, a well-characterized toughened epoxy carbon fiber reinforced polymer (CFRP) composite. The resin content of these interleaved CNT sheets, as well as ply stacking location were varied to determine the effects on the electrical, thermal, and mechanical performance of the composites. The direct-current electrical conductivity of the hybrid CNT composites was characterized by in-line and Montgomery four-probe methods. For [0](sub 20) laminates containing a single layer of CNT sheet between each ply of IM7/8552, in-plane electrical conductivity of the hybrid laminate increased significantly, while in-plane thermal conductivity increased only slightly in comparison to the control IM7/8552 laminates. Photo-microscopy and short beam shear (SBS) strength tests were used to characterize the consolidation quality of the fabricated laminates. Hybrid panels fabricated without any pretreatment of the CNT sheets resulted in a SBS strength reduction of 70 percent. Aligning the tubes and pre-infusing the CNT sheets with resin significantly improved the SBS strength of the hybrid composite To determine the cause of this performance reduction, Mode I and Mode II fracture toughness of the CNT sheet to CFRP interface was characterized by double cantilever beam (DCB) and end notch flexure (ENF) testing, respectively. Results are compared to the

  9. High strain rate characterization of polymers

    NASA Astrophysics Data System (ADS)

    Siviour, Clive R.

    2017-01-01

    This paper reviews the literature on the response of polymers to high strain rate deformation. The main focus is on the experimental techniques used to characterize this response. The paper includes a small number of examples as well as references to experimental data over a wide range of rates, which illustrate the key features of rate dependence in these materials; however this is by no means an exhaustive list. The aim of the paper is to give the reader unfamiliar with the subject an overview of the techniques available with sufficient references from which further information can be obtained. In addition to the `well established' techniques of the Hopkinson bar, Taylor Impact and Transverse impact, a discussion of the use of time-temperature superposition in interpreting and experimentally replicating high rate response is given, as is a description of new techniques in which mechanical parameters are derived by directly measuring wave propagation in specimens; these are particularly appropriate for polymers with low wave speeds. The vast topic of constitutive modelling is deliberately excluded from this review.

  10. Physical and Electrical Characterization of Aluminum Polymer Capacitors

    NASA Technical Reports Server (NTRS)

    Liu, David; Sampson, Michael J.

    2010-01-01

    Polymer aluminum capacitors from several manufacturers with various combinations of capacitance, rated voltage, and ESR values were physically examined and electrically characterized. The physical construction analysis of the capacitors revealed three different capacitor structures, i.e., traditional wound, stacked, and laminated. Electrical characterization results of polymer aluminum capacitors are reported for frequency-domain dielectric response at various temperatures, surge breakdown voltage, and other dielectric properties. The structure-property relations in polymer aluminum capacitors are discussed.

  11. Physical and Electrical Characterization of Polymer Aluminum Capacitors

    NASA Technical Reports Server (NTRS)

    Liu, David; Sampson, Michael J.

    2010-01-01

    Polymer aluminum capacitors from several manufacturers with various combinations of capacitance, rated voltage, and ESR values were physically examined and electrically characterized. The physical construction analysis of the capacitors revealed three different capacitor structures, i.e., traditional wound, stacked, and laminated. Electrical characterization results of polymer aluminum capacitors are reported for frequency-domain dielectric response at various temperatures, surge breakdown voltage, and other dielectric properties. The structure-property relations in polymer aluminum capacitors are discussed.

  12. Characterization of dielectric electroactive polymer transducers

    NASA Astrophysics Data System (ADS)

    Nielsen, Dennis; Møller, Martin B.; Sarban, Rahimullah; Lassen, Benny; Knott, Arnold; Andersen, Michael A. E.

    2014-03-01

    Throughout this paper, a small-signal model of the Dielectric Electro Active Polymer (DEAP) transducer is analyzed. The DEAP transducer have been proposed as an alternative to the electrodynamic transducer in sound reproduction systems. In order to understand how the DEAP transducer works, and provide guidelines for design optimization, accurate characterization of the transducer must be established. A small signal model of the DEAP transducer is derived and its validity is investigated using impedance measurements. Impedance measurements are shown for a push-pull DEAP based loudspeaker, and the dependency of the biasing voltage is explained. A measuring setup is proposed, which allows the impedance to be measured, while the DEAP transducer is connected to its biasing source.

  13. Studies on three-dimensional coordination polymer [Cd2(N2H4)2(N3)4]n: crystal structure, thermal decomposition mechanism and explosive properties.

    PubMed

    Liu, Zhenhua; Zhang, Tonglai; Zhang, Jianguo; Wang, Shaozong

    2008-06-15

    A 3D coordination polymer of cadmium(II) hydrazine azide, [Cd2(N2H4)2(N3)4]n, was synthesized and characterized by elemental analysis and Fourier transform infrared (FT-IR) spectrum. Its crystal structure was determined by single crystal X-ray diffraction analysis. The crystal belongs to monoclinic, P2(1)/c space group, a=12.555(2)A, b=11.724(2)A, c=7.842(1)A, beta=94.56(2) degrees and Z=4. The crystal contains two crystallographically independent sets of distorted octahedral Cd(II) atoms and dimeric units of Cd2N2, Cd2(NNN)2, Cd2(NN)2 through double micro-1, 1 azide bridges, micro-1, 3 azide bridges and bidentate bridging hydrazine ligands, respectively, and thus generating a 3D network structure. The thermal decomposition mechanism of the complex was studied by using differential scanning calorimetry (DSC), thermogravimetry-derivative thermogravimetry (TG-DTG) and FT-IR techniques. Under nitrogen atmosphere with a heating rate of 10 degrees C/min, the thermal decomposition of the complex contained two intense exothermic decomposition processes in the range of 150-304 degrees C in the DSC curve, and the final decomposed residue at 500 degrees C was Cd. Sensitivity tests revealed that the title complex is very insensitive to external stimuli.

  14. Synthesis, crystal structure and catalytic effect on thermal decomposition of RDX and AP: An energetic coordination polymer [Pb{sub 2}(C{sub 5}H{sub 3}N{sub 5}O{sub 5}){sub 2}(NMP)·NMP]{sub n}

    SciTech Connect

    Liu, Jin-jian; Liu, Zu-Liang; Cheng, Jian; Fang, Dong

    2013-04-15

    An energetic lead(II) coordination polymer based on the ligand ANPyO has been synthesized and its crystal structure has been got. The polymer was characterized by FT-IR spectroscopy, elemental analysis, DSC and TG-DTG technologies. Thermal analysis shows that there are one endothermic process and two exothermic decomposition stages in the temperature range of 50–600 °C with final residues 57.09%. The non-isothermal kinetic has also been studied on the main exothermic decomposition using the Kissinger's and Ozawa–Doyle's methods, the apparent activation energy is calculated as 195.2 KJ/mol. Furthermore, DSC measurements show that the polymer has significant catalytic effect on the thermal decomposition of ammonium perchlorate. - Graphical abstract: An energetic lead(II) coordination polymer of ANPyO has been synthesized, structurally characterized and properties tested. Highlights: ► We have synthesized and characterized an energetic lead(II) coordination polymer. ► We have measured its molecular structure and thermal decomposition. ► It has significant catalytic effect on thermal decomposition of AP.

  15. Yttrium-succinates coordination polymers: Hydrothermal synthesis, crystal structure and thermal decomposition

    SciTech Connect

    Amghouz, Zakariae; Roces, Laura; Garcia-Granda, Santiago; Garcia, Jose R.; Souhail, Badredine; Mafra, Luis; Shi, Fa-nian; Rocha, Joao

    2009-12-15

    New polymeric yttrium-succinates, Y{sub 2}(C{sub 4}H{sub 4}O{sub 4}){sub 3}(H{sub 2}O){sub 4}.6H{sub 2}O and Y{sub 2}(C{sub 4}H{sub 4}O{sub 4}){sub 3}(H{sub 2}O){sub 2}, have been synthesized, and their structures (solved by single crystal XRD) are compared with that of Y{sub 2}(C{sub 4}H{sub 4}O{sub 4}){sub 3}(H{sub 2}O){sub 2}.H{sub 2}O. Three compounds were obtained as single phases, and their thermal behaviour is described. - Graphical abstract: In the field of coordination polymers or MOF's, few studies report on the polymorphs of Ln(III)-succinic acid. Here, we describe the hydrothermal synthesis and structural characterization of two novel yttrium-succinates coordination polymers, respectively 2D and 3D, Y{sub 2}(C{sub 4}H{sub 4}O{sub 4}){sub 3}(H{sub 2}O){sub 4}.6H{sub 2}O and Y{sub 2}(C{sub 4}H{sub 4}O{sub 4}){sub 3}(H{sub 2}O){sub 2}.

  16. Synthesis and characterization of conducting polymer inserted carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Choi, A. Jeong; Nam, Young Woo; Park, Yung Woo

    2008-03-01

    The carbon nanotubes filled with the photo-conducting polymer poly(N-vinyl carbazole) and the conducting polymer polypyrrole were prepared by polymerizing the monomers inside the nanotubes using the supercritical carbon dioxide. The endohedral nanotubes were characterized by HRTEM and ^1H NMR, which confirmed that the inserted material was indeed the conducting polymer [1]. I-V characteristics of the polymer inserted carbon nanotubes are presented. [1] Johannes Steinmetz, Soyoung Kwon, Hyun-Jung Lee, Edy Abou-Hamad, Robert Almairac, Christophe Goze-Bac, Hwayong Kim, Yung-Woo Park,, Chem. Phys. Lett., 431, 139 (2006)

  17. Polymer-Peptide Nanoparticles: Synthesis and Characterization

    NASA Astrophysics Data System (ADS)

    Dong, He; Shu, Jessica Y.; Xu, Ting

    2010-03-01

    Conjugation of synthetic polymers to peptides offers an efficient way to produce novel supramolecular structures. Herein, we report an attempt to prepare synthetic micellar nanoparticles using amphiphilic peptide-polymer conjugates as molecular building blocks. Spherical nanoparticles were formed upon dissolution of peptides in PBS buffer through the segregation of hydrophobic and hydrophilic segments. Both molecular and nano- structures were thoroughly investigated by a variety of biophysical techniques, including circular dichroism (CD), dynamic light scattering (DLS), size exclusion chromatography (SEC), transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). The results demonstrate that structural properties of these biohybrid materials depend on both the geometry of the hydrophobic domain and the size of synthetic polymers. Given the diversity of functional peptide sequences, hydrophilic polymers and hydrophobic moieties, these materials would be expected to self-assemble into various types of nanostructures to cover a wide range of biological applications.

  18. Synthesis, spectral characterization and thermal aspects of coordination polymers of some transition metal ions with adipoyl bis(isonicotinoylhydrazone)

    NASA Astrophysics Data System (ADS)

    Haque, Mahejabeen Azizul; Paliwal, L. J.

    2017-04-01

    A series of metal coordination polymers of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II), obtained by the reaction of metal acetate with newly synthesized adipoyl bis(isonicotinoylhydrazone) (ADBI) have been investigated. The ligand has been characterized by 1H NMR, 13C NMR, FTIR, and ESI mass spectra. Structural and spectroscopic characterization of the coordination polymers have been carried out using elemental analysis, XRD, SEM, infrared and diffused reflectance spectra, magnetic susceptibility measurements and thermogravimetric analytical techniques. Each metal ion is coordinated to the ligand through oxygen of carbonyl group and the nitrogen of azomethine group of ligand forming a stable 5-membered heterocyclic ring. The synthesized ligand coordinates in an octadentate manner. Magnetic and diffused reflectance spectral studies reveal octahedral geometry of Co(II), Cu(II), Fe(II) and Ni(II) coordination polymers and tetrahedral geometry of Mn(II) and Zn(II) coordination polymers. The thermal stability and decomposition steps of all coordination polymers have been studied using TG, DTG and DTA techniques. Moreover, the kinetic parameters such as activation energy (Ea*), order of reaction (n), Arrhenius factor (A), change in entropy (ΔS*), change in enthalpy (ΔH*) and free energy change (ΔG*) were evaluated at each stage of decomposition curve using Coats-Redfern method.

  19. Characterization of explosives processing waste decomposition due to composting

    SciTech Connect

    Griest, W.H.; Tyndall, R.L.; Stewart, A.J.; Ho, C.H.; Ironside, K.S.; Caton, J.E.; Caldwell, W.M.; Tan, E.

    1991-11-01

    Static pile and mechanically stirred composts generated at the Umatilla Army Depot Activity in a field composting optimization study were chemically and toxicologically characterized to provide data for the evaluation of composting efficiency to decontaminate and detoxify explosives-contaminated soil. Characterization included determination of explosives and 2,4,6,-trinitrotoluene metabolites in composts and their EPA Synthetic Precipitation Leaching Procedure Leachates, leachate toxicity to Ceriodaphnia Dubia and mutagenicity of the leachates and organic solvent extracts of the composts to Ames bacterial strains TA-98 and TA-100. The main conclusion from this study is that composting can effectively reduce the concentrations of explosives and bacterial mutagenicity in explosives -- contaminated soil, and can reduce the aquatic toxicity of leachable compounds. Small levels of explosive and metabolites, bacterial mutagenicity, and leachable aquatic toxicity remain after composting. The ultimate fate of the biotransformed explosives, and the source(s) of residual toxicity and mutagenicity remain unknown.

  20. Characterizing abrupt changes in the stock prices using a wavelet decomposition method

    NASA Astrophysics Data System (ADS)

    Caetano, Marco Antonio Leonel; Yoneyama, Takashi

    2007-09-01

    Abrupt changes in the stock prices, either upwards or downwards, are usually preceded by an oscillatory behavior with frequencies that tend to increase as the moment of transition becomes closer. The wavelet decomposition methods may be useful for analysis of this oscillations with varying frequencies, because they provide simultaneous information on the frequency (scale) and localization in time (translation). However, in order to use the wavelet decomposition, certain requirements have to be satisfied, so that the linear and cyclic trends are eliminated by standard least squares techniques. The coefficients obtained by the wavelet decomposition can be represented in a graphical form. A threshold can then be established to characterize the likelihood of a short-time abrupt change in the stock prices. Actual data from the São Paulo Stock Exchange (Bolsa de Valores de São Paulo) were used in this work to illustrate the proposed method.

  1. Decomposition of 2-chloroethylethylsulfide on copper oxides to detoxify polymer-based spherical activated carbons from chemical warfare agents.

    PubMed

    Fichtner, S; Hofmann, J; Möller, A; Schrage, C; Giebelhausen, J M; Böhringer, B; Gläser, R

    2013-11-15

    For the decomposition of chemical warfare agents, a hybrid material concept was applied. This consists of a copper oxide-containing phase as a component with reactive functionality supported on polymer-based spherical activated carbon (PBSAC) as a component with adsorptive functionality. A corresponding hybrid material was prepared by impregnation of PBSAC with copper(II)nitrate and subsequent calcination at 673K. The copper phase exists predominantly as copper(I)oxide which is homogeneously distributed over the PBSAC particles. The hybrid material containing 16 wt.% copper on PBSAC is capable of self-detoxifying the mustard gas surrogate 2-chloroethylethylsulfide (CEES) at room temperature. The decomposition is related to the breakthrough behavior of the reactant CEES, which displaces the reaction product ethylvinylsulfide (EVS). This leads to a combined breakthrough of CEES and EVS. The decomposition of CEES is shown to occur catalytically over the copper-containing PBSAC material. Thus, the hybrid material can even be considered to be self-cleaning.

  2. Characterizing SWCNT Dispersion in Polymer Composites

    NASA Technical Reports Server (NTRS)

    Lillehei, Peter T.; Kim, Jae-Woo; Gibbons, Luke; Park, Cheol

    2007-01-01

    The new wave of single wall carbon nanotube (SWCNT) infused composites will yield structurally sound multifunctional nanomaterials. The SWCNT network requires thorough dispersion within the polymer matrix in order to maximize the benefits of the nanomaterial. However, before any nanomaterials can be used in aerospace applications a means of quality assurance and quality control must be certified. Quality control certification requires a means of quantification, however, the measurement protocol mandates a method of seeing the dispersion first. We describe here the new tools that we have developed and implemented to first be able to see carbon nanotubes in polymers and second to measure or quantify the dispersion of the nanotubes.

  3. Kinetic and chemical characterization of thermal decomposition of dicumylperoxide in cumene.

    PubMed

    Di Somma, Ilaria; Marotta, Raffaele; Andreozzi, Roberto; Caprio, Vincenzo

    2011-03-15

    Dicumylperoxide (DCP) is one of the most used peroxides in the polymer industry. It has been reported that its thermal decomposition can result in runaway phenomena and thermal explosions with significant economic losses and injuries to people. In the present paper thermal behaviour of dicumylperoxide in cumene was investigated over the temperature range of 393-433 K under aerated and de-aerated conditions. The results indicated that when oxygen was present, the decomposition rate did not follow a simple pseudo-first order kinetic as previously reported in literature. A satisfactory fit of the experimental data was, in this case, achieved by means of kinetic expression derived under the assumption of an autocatalytic scheme of reaction. The reaction rate was, on the contrary, correctly described by a pseudo-first order kinetic in absence of oxygen. Under both aerated and de-aerated conditions, chemical analysis showed that the decomposition mainly resulted in the formation of acetophenone and dimethylphenylcarbinol with minor occurrence of 2,3-dimethyl-2,3-diphenylbutane. The formation of methane and ethane was also invariably observed while the appearance of cumylhydroperoxide as a reaction intermediate was detected under only aerated conditions. Therefore, two reaction schemes were proposed to explain system behaviour in the presence of oxygen and after its purging.

  4. Isotropic photo-decomposition of spherical organic polymers on rutile TiO₂(110) surfaces.

    PubMed

    Ishida, Nobuyuki; Iwasaki, Tamaki; Fujita, Daisuke

    2011-04-15

    We observed the photo-decomposition process of polystyrene latex (PSL) spheres on a rutile TiO₂(110) single crystal surface by using atomic force microscopy. During the decomposition process, both the height and width of the PSL spheres linearly decreased with the irradiation time in a similar way from the beginning, suggesting that the PSL spheres are isotropically decomposed. This indicates that the interface between the PSL spheres and the TiO₂ surface is not a dominant reaction site, as expected from normal photocatalytic reactions.

  5. Synthesis and characterizations of novel polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Chanthad, Chalathorn

    Polymer electrolytes are an important component of many electrochemical devices. The ability to control the structures, properties, and functions of polymer electrolytes remains a key subject for the development of next generation functional polymers. Taking advantage of synthetic strategies is a promising approach to achieve the desired chemical structures, morphologies, thermal, mechanical, and electrochemical properties. Therefore, the major goal of this thesis is to develop synthetic methods for of novel proton exchange membranes and ion conductive membranes. In Chapter 2, new classes of fluorinated polymer- polysilsesquioxane nanocomposites have been designed and synthesized. The synthetic method employed includes radical polymerization using the functional benzoyl peroxide initiator for the telechelic fluorinated polymers with perfluorosulfonic acids in the side chains and a subsequent in-situ sol-gel condensation of the prepared triethoxylsilane-terminated fluorinated polymers with alkoxide precursors. The properties of the composite membranes have been studied as a function of the content and structure of the fillers. The proton conductivity of the prepared membranes increases steadily with the addition of small amounts of the polysilsesquioxane fillers. In particular, the sulfopropylated polysilsesquioxane based nanocomposites display proton conductivities greater than Nafion. This is attributed to the presence of pendant sulfonic acids in the fillers, which increases ion-exchange capacity and offers continuous proton transport channels between the fillers and the polymer matrix. The methanol permeability of the prepared membranes has also been examined. Lower methanol permeability and higher electrochemical selectivity than those of Nafion have been demonstrated in the polysilsesquioxane based nanocomposites. In Chapter 3, the synthesis of a new class of ionic liquid-containing triblock copolymers with fluoropolymer mid-block and imidazolium methacrylate

  6. Image characterization by fractal descriptors in variational mode decomposition domain: Application to brain magnetic resonance

    NASA Astrophysics Data System (ADS)

    Lahmiri, Salim

    2016-08-01

    The main purpose of this work is to explore the usefulness of fractal descriptors estimated in multi-resolution domains to characterize biomedical digital image texture. In this regard, three multi-resolution techniques are considered: the well-known discrete wavelet transform (DWT) and the empirical mode decomposition (EMD), and; the newly introduced; variational mode decomposition mode (VMD). The original image is decomposed by the DWT, EMD, and VMD into different scales. Then, Fourier spectrum based fractal descriptors is estimated at specific scales and directions to characterize the image. The support vector machine (SVM) was used to perform supervised classification. The empirical study was applied to the problem of distinguishing between normal and abnormal brain magnetic resonance images (MRI) affected with Alzheimer disease (AD). Our results demonstrate that fractal descriptors estimated in VMD domain outperform those estimated in DWT and EMD domains; and also those directly estimated from the original image.

  7. Combined photothermal lens and photothermal mirror characterization of polymers.

    PubMed

    Aréstegui, Odon S; Poma, Patricia Y N; Herculano, Leandro S; Lukasievicz, Gustavo V B; Guimarães, Francine B; Malacarne, Luis C; Baesso, Mauro L; Bialkowski, Stephen E; Astrath, Nelson G C

    2014-01-01

    We propose a combined thermal lens and thermal mirror method as concurrent photothermal techniques for the physical characterization of polymers. This combined method is used to investigate polymers as a function of temperature from room temperature up to 170 °C. The method permits a direct determination of thermal diffusivity and thermal conductivity. Additional measurements of specific heat, linear thermal expansion, and temperature-dependent optical path change are also performed. A complete set of thermal, optical, and mechanical properties of polycarbonate and poly (methyl methacrylate) samples are obtained. Methods presented here can be useful for in situ characterization of semitransparent materials, where fast and non-contacting measurements are required.

  8. Characterization and characteristics of degradable polymer sacks

    SciTech Connect

    Davis, Georgina

    2003-10-15

    This paper reviews the categories and characteristics of degradable polymers used to manufacture sacks for the collection and subsequent treatment of organic wastes from householders. The characteristics of polyethylene (PE) and starch-based sacks were examined using a number of different methods, including scanning electron microscopy (SEM), chemical analysis and mechanical strength testing of the sacks during their use. The analyses revealed that the characteristics of the PE and starch-based sacks were very different. Photomicrographs indicated that the surface of the PE sack was much smoother than the surface of the starch-based sacks. Polyethylene sacks exhibited a greater mechanical strength, both in the unused state and over time during householder use. The severe loss of mechanical strength during use of the starch-based sacks indicated that only thicker gauge sacks were suitable for the fortnightly kerbside collection of biodegradable municipal waste (BMW). Chemical analysis of two different PE sacks indicated that transition metals and other elements were commonly incorporated into the PE structure in order to facilitate increased polymer degradation.

  9. Assessment of a new method for the analysis of decomposition gases of polymers by a combining thermogravimetric solid-phase extraction and thermal desorption gas chromatography mass spectrometry.

    PubMed

    Duemichen, E; Braun, U; Senz, R; Fabian, G; Sturm, H

    2014-08-08

    For analysis of the gaseous thermal decomposition products of polymers, the common techniques are thermogravimetry, combined with Fourier transformed infrared spectroscopy (TGA-FTIR) and mass spectrometry (TGA-MS). These methods offer a simple approach to the decomposition mechanism, especially for small decomposition molecules. Complex spectra of gaseous mixtures are very often hard to identify because of overlapping signals. In this paper a new method is described to adsorb the decomposition products during controlled conditions in TGA on solid-phase extraction (SPE) material: twisters. Subsequently the twisters were analysed with thermal desorption gas chromatography mass spectrometry (TDS-GC-MS), which allows the decomposition products to be separated and identified using an MS library. The thermoplastics polyamide 66 (PA 66) and polybutylene terephthalate (PBT) were used as example polymers. The influence of the sample mass and of the purge gas flow during the decomposition process was investigated in TGA. The advantages and limitations of the method were presented in comparison to the common analysis techniques, TGA-FTIR and TGA-MS.

  10. Characterization of chitosan composites with synthetic polymers and inorganic additives.

    PubMed

    Lewandowska, Katarzyna

    2015-11-01

    In the present study, the results from thermogravimetric analysis (TGA), contact angle measurements, tensile tests, scanning electron microscopy (SEM) and atomic force microscopy (AFM) of polymer composites containing chitosan (Ch) and montmorillonite (MMT) with and without poly(vinyl alcohol) (PVA) are presented. Measurements of the contact angles for diiodomethane (D) and glycerol (G) on the surfaces of chitosan films, Ch/MMT and Ch/PVA/MMT, were made and surface free energies were calculated. It was found that the wettability of the chitosan/MMT or Ch/PVA/MMT composite films decreased relative to the wettability of chitosan. The microstructure of unmodified polymers and their composites, as observed by SEM and AFM, showed particles that are relatively well dispersed in the polymer matrix. The TGA thermograms and mass loss percentages at different decomposition temperatures showed that the thermal stability of the binary composite slightly decreases upon the addition of PVA. The film mechanical properties such as tensile strength, Young's modulus and tensile strain at break depend on the composition and varied non-uniformly. Both composites possessed a tensile strength and Young's modulus of 27.6-94.3MPa and 1.5-3.5GPa, respectively. The addition of PVA to the composite led to a reduction in tensile strength by approximately 40%.

  11. Characterization of polymer based nanocomposites with carbon nanotubes.

    PubMed

    Ciecierska, Ewelina; Boczkowska, Anna; Kurzydłowski, Krzysztof J

    2014-04-01

    The paper concerns investigation of the processing methods influence on the electrical, thermal and mechanical properties of the polymer matrix nanocomposites with carbon nanotubes (CNTs) as a filler. The focus is put on the relation between microstructure and properties dependently on the parameters of mixing, epoxy matrix curing parameters, neat epoxy resin viscosity, carbon nanotubes modified with different functional groups, as well as carbon nanotubes weight fraction. Nanocomposites with the CNTs varied from 0.05 to 5 wt.% were obtained by dispersion methods such as: mechanical stirring, ultrasonication and combination both of them, as well as calendaring. Three epoxy resin systems were tested, varied in viscosity and curing temperature. Also CNTs nonmodified and modified with amino, carboxyl and hydroxyl groups were used. The choice of the best epoxy resin system and kind of CNTs for fabrication of conductive nanocomposites was done. The lower neat epoxy resin viscosity the better dispersion of CNTs can be achieved. The distribution of CNTs in the epoxy matrix was evaluated using high resolution scanning electron microscopy, supported by image analysis. Electrical conductivity, as well as thermal stability and thermodynamic properties of polymers filled with CNTs were determined. Activation energy of decomposition process was calculated from thermogravimetric curves by Flynn-Wall-Ozawa method. The deterioration of thermal stability was obtained, while mechanical properties increase with the CNTs weight fraction growth up to 0.1%. Calendaring was found as the best method of CNTs dispersion in the polymer matrix.

  12. Combined TGA-MS kinetic analysis of multistep processes. Thermal decomposition and ceramification of polysilazane and polysiloxane preceramic polymers.

    PubMed

    García-Garrido, C; Sánchez-Jiménez, P E; Pérez-Maqueda, L A; Perejón, A; Criado, José M

    2016-10-26

    The polymer-to-ceramic transformation kinetics of two widely employed ceramic precursors, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (TTCS) and polyureamethylvinylsilazane (CERASET), have been investigated using coupled thermogravimetry and mass spectrometry (TG-MS), Raman, XRD and FTIR. The thermally induced decomposition of the pre-ceramic polymer is the critical step in the synthesis of polymer derived ceramics (PDCs) and accurate kinetic modeling is key to attaining a complete understanding of the underlying process and to attempt any behavior predictions. However, obtaining a precise kinetic description of processes of such complexity, consisting of several largely overlapping physico-chemical processes comprising the cleavage of the starting polymeric network and the release of organic moieties, is extremely difficult. Here, by using the evolved gases detected by MS as a guide it has been possible to determine the number of steps that compose the overall process, which was subsequently resolved using a semiempirical deconvolution method based on the Frasier-Suzuki function. Such a function is more appropriate that the more usual Gaussian or Lorentzian functions since it takes into account the intrinsic asymmetry of kinetic curves. Then, the kinetic parameters of each constituent step were independently determined using both model-free and model-fitting procedures, and it was found that the processes obey mostly diffusion models which can be attributed to the diffusion of the released gases through the solid matrix. The validity of the obtained kinetic parameters was tested not only by the successful reconstruction of the original experimental curves, but also by predicting the kinetic curves of the overall processes yielded by different thermal schedules and by a mixed TTCS-CERASET precursor.

  13. Synthesis and characterization of polymer matrix nanocomposites and their components

    NASA Astrophysics Data System (ADS)

    Burnside, Shelly Dawn

    Herein we present synthesis schemes and characterization results for polymer matrix nanocomposite reinforced with organically modified layered silicates. These host materials with ultrafine dimensions are promising candidates for polymer and have been previously shown to yield substantial property enhancements at low silicate loadings due to their extreme geometry. Siloxane nanocomposites with a variety of nanostructures were formed. Thermal stability, solvent uptake and moduli of the nanocomposites were explores. Exfoliated nanocomposites displayed enhanced properties when compared to unreinforced siloxanes, and at lower volume fraction filler than in conventional composites. Large amounts of bound polymer, polymer affected by the silicate, were found in exfoliated nanocomposites as a result of the extreme geometry of the layered silicate. This bound polymer was related to the dramatic property enhancements in the nanocomposites. The behavior of these nanocomposites is compared to behavior expected from traditional models developed for conventional composites and model elastomeric networks. A lightly brominated polymer has been intercalated into a single crystal of organically exchanged vermiculite. The intercalation was followed using x-ray diffraction by monitoring the gallery height of the vermiculite host. Rutherford Backscattering Spectroscopy, used to confirm polymer intercalation, showed a constant bromine content in the direction normal to the layers. Atomic Force Microscopy images of a cleaved polymer-intercalated crystal showed raised hemispheres on an otherwise flat background. The hemispheres consist of single chains or aggregates of 3-40 polymer chains resulting from relaxations following cleaving. Three component or Hansen solubility parameters (delta) of organically modified layered silicates, the reinforcing agent in polymer matrix nanocomposites presented herein, have been determined. Two experimental techniques, temporal turbidimetry and

  14. Synthesis and characterization of some transition metals polymer complexes

    NASA Astrophysics Data System (ADS)

    Masoud, Mamdouh S.; Abdou, Azza E. H.; Ahmed, Wael M.

    2015-09-01

    Co2+, Ni2+, Cu2+, Cr3+, Mn2+ and Fe3+ complexes of Polyacrylamide are prepared and characterized by elemental analyses, IR, UV-Vis spectra, magnetic measurements, and thermal analyses. The data suggests octahedral geometry for all complexes. The thermal behavior of the complexes has been studied applying TG, DTA, and DSC techniques, and the thermodynamic parameters and mechanisms of the decompositions were evaluated. The ΔS# values of the decomposition steps of the metal complexes indicated that the activated fragments have more ordered structure than the undecomposed complexes. The thermal processes proceeded in complicated mechanisms where the bond between the central metal ion and the ligands dissociates after losing 6(C2H5 N) and 6(CO), the metal complexes are ended with metal as a final product. Viscosity and Shale instability using liner swell meter were carried out. Comparisons of the experimental and theoretical IR spectra were also carried out besides some other theoretical calculations.

  15. Characterization of naproxen-polymer conjugates for drug-delivery.

    PubMed

    Forte, Gianpiero; Chiarotto, Isabella; Giannicchi, Ilaria; Loreto, Maria Antonietta; Martinelli, Andrea; Micci, Roberta; Pepi, Federico; Rossi, Serena; Salvitti, Chiara; Stringaro, Annarita; Tortora, Luca; Vecchio Ciprioti, Stefano; Feroci, Marta

    2016-01-01

    The synthesis and the characterization of three new naproxen decorated polymers are described. A versatile and general approach is employed to link the drug to polymers, affording the derivatives with a very high degree of purity. The release of the drug from the conjugates proved to be exceptionally slow, even in acidic aqueous media, and the kinetic of the process seems to be triggered by their solubility in water. On the other hand, the interesting outcome of the first ex vivo drug release experiments on human blood samples makes this preliminary study valuable for future investigations on the use of these polymeric prodrugs in in vivo treatment of inflammatory states.

  16. Fourier decomposition of polymer orientation in large-amplitude oscillatory shear flow

    DOE PAGES

    Giacomin, A. J.; Gilbert, P. H.; Schmalzer, A. M.

    2015-03-19

    In our previous work, we explored the dynamics of a dilute suspension of rigid dumbbells as a model for polymeric liquids in large-amplitude oscillatory shear flow, a flow experiment that has gained a significant following in recent years. We chose rigid dumbbells since these are the simplest molecular model to give higher harmonics in the components of the stress response. We derived the expression for the dumbbell orientation distribution, and then we used this function to calculate the shear stress response, and normal stress difference responses in large-amplitude oscillatory shear flow. In this paper, we deepen our understanding of themore » polymer motion underlying large-amplitude oscillatory shear flow by decomposing the orientation distribution function into its first five Fourier components (the zeroth, first, second, third, and fourth harmonics). We use three-dimensional images to explore each harmonic of the polymer motion. Our analysis includes the three most important cases: (i) nonlinear steady shear flow (where the Deborah number λω is zero and the Weissenberg number λγ 0 is above unity), (ii) nonlinear viscoelasticity (where both λω and λγ 0 exceed unity), and (iii) linear viscoelasticity (where λω exceeds unity and where λγ 0 approaches zero). We learn that the polymer orientation distribution is spherical in the linear viscoelastic regime, and otherwise tilted and peanut-shaped. We find that the peanut-shaping is mainly caused by the zeroth harmonic, and the tilting, by the second. The first, third, and fourth harmonics of the orientation distribution make only slight contributions to the overall polymer motion.« less

  17. Fourier decomposition of polymer orientation in large-amplitude oscillatory shear flow

    SciTech Connect

    Giacomin, A. J.; Gilbert, P. H.; Schmalzer, A. M.

    2015-03-19

    In our previous work, we explored the dynamics of a dilute suspension of rigid dumbbells as a model for polymeric liquids in large-amplitude oscillatory shear flow, a flow experiment that has gained a significant following in recent years. We chose rigid dumbbells since these are the simplest molecular model to give higher harmonics in the components of the stress response. We derived the expression for the dumbbell orientation distribution, and then we used this function to calculate the shear stress response, and normal stress difference responses in large-amplitude oscillatory shear flow. In this paper, we deepen our understanding of the polymer motion underlying large-amplitude oscillatory shear flow by decomposing the orientation distribution function into its first five Fourier components (the zeroth, first, second, third, and fourth harmonics). We use three-dimensional images to explore each harmonic of the polymer motion. Our analysis includes the three most important cases: (i) nonlinear steady shear flow (where the Deborah number λω is zero and the Weissenberg number λγ 0 is above unity), (ii) nonlinear viscoelasticity (where both λω and λγ 0 exceed unity), and (iii) linear viscoelasticity (where λω exceeds unity and where λγ 0 approaches zero). We learn that the polymer orientation distribution is spherical in the linear viscoelastic regime, and otherwise tilted and peanut-shaped. We find that the peanut-shaping is mainly caused by the zeroth harmonic, and the tilting, by the second. The first, third, and fourth harmonics of the orientation distribution make only slight contributions to the overall polymer motion.

  18. Damage characterization for particles filled semi-crystalline polymer

    NASA Astrophysics Data System (ADS)

    Lauro, Franck; Balieu, Romain; Bennani, Bruno; Haugou, Gregory; Bourel, Benjamin; Chaari, Fahmi; Matsumoto, Tsukatada; Mottola, Ernesto

    2015-09-01

    Damage evolution and characterization in semi-crystalline polymer filled with particles under various loadings is still a challenge. A specific damage characterization method using Digital Image Correlation is proposed for a wide range of strain rates considering tensile tests with hydraulic jacks as well as Hopkinson's bars. This damage measurement is obtained by using and adapting the SEE method [1] which was developed to characterize the behaviour laws at constant strain rates of polymeric materials in dynamic. To validate the characterization process, various damage measurement techniques are used under quasi-static conditions before to apply the procedure in dynamic. So, the well-known damage characterization by loss of stiffness technique under quasi-static loading is applied to a polypropylene. In addition, an in-situ tensile test, carried out in a microtomograph, is used to observe the cavitation phenomenon in real time. A good correlation is obtained between all these techniques and consequently the proposed technique is supposed suitable for measuring the ductile damage observed in semi-crystalline polymers under dynamic loading. By applying it to the semi-crystalline polymer at moderate and high speed loadings, the damage evolution is measured and it is observed that the damage evolution is not strain rate dependent but the failure strain on the contrary is strain rate dependent.

  19. A Perturbation Based Decomposition of Compound-Evoked Potentials for Characterization of Nerve Fiber Size Distributions.

    PubMed

    Szlavik, Robert B

    2016-02-01

    The characterization of peripheral nerve fiber distributions, in terms of diameter or velocity, is of clinical significance because information associated with these distributions can be utilized in the differential diagnosis of peripheral neuropathies. Electro-diagnostic techniques can be applied to the investigation of peripheral neuropathies and can yield valuable diagnostic information while being minimally invasive. Nerve conduction velocity studies are single parameter tests that yield no detailed information regarding the characteristics of the population of nerve fibers that contribute to the compound-evoked potential. Decomposition of the compound-evoked potential, such that the velocity or diameter distribution of the contributing nerve fibers may be determined, is necessary if information regarding the population of contributing nerve fibers is to be ascertained from the electro-diagnostic study. In this work, a perturbation-based decomposition of compound-evoked potentials is proposed that facilitates determination of the fiber diameter distribution associated with the compound-evoked potential. The decomposition is based on representing the single fiber-evoked potential, associated with each diameter class, as being perturbed by contributions, of varying degree, from all the other diameter class single fiber-evoked potentials. The resultant estimator of the contributing nerve fiber diameter distribution is valid for relatively large separations in diameter classes. It is also useful in situations where the separation between diameter classes is small and the concomitant single fiber-evoked potentials are not orthogonal.

  20. Characterization of polymer films for use in bimorph chemical sensors

    NASA Astrophysics Data System (ADS)

    Chatzandroulis, S.; Goustouridis, D.; Raptis, I.

    2005-01-01

    In the present work white light interferometry is applied for the characterization of polymer films commonly used in bimorph chemical sensors. The study focuses on methacrylate polymers with positive tone patterning capabilities. The behavior upon exposure to controlled concentrations volatile organic compound and water vapors of thin poly (hydroxy ethyl methacrylate) (PHEMA) and poly (methyl methacrylate) (PMMA) layers was evaluated. The normalized film expansion for PHEMA, compared to PMMA, is higher in the case of water and methanol vapors, almost equal for ethanol and significantly lower in the case of acetone. This behavior could be attributed to the combination of polarity and hydrogen bonding capability of the analytes. A wide polymer film thickness range was examined and it was revealed that the normalized film expansion in both PHEMA and PMMA is nearly constant for films thicker than 100 nm and increases for thinner films.

  1. Preparation and Characterization of Nateglinide Loaded Hydrophobic Biocompatible Polymer Nanoparticles

    NASA Astrophysics Data System (ADS)

    Naik, Jitendra; Lokhande, Amolkumar; Mishra, Satyendra; Kulkarni, Ravindra

    2016-09-01

    The aim of the present study was to develop sustained release Nateglinide loaded Ethylcellulose nanoparticles and characterize the properties of recovered nanoparticles. The sustained release nanoparticles were prepared by oil in water single emulsion solvent evaporation method. The developed nanoparticles were characterised for their particle size, morphology, encapsulation efficiency, drug polymer compatibility and in vitro drug release. The drug polymer compatibility was investigated by XRPD. Imaging of particles was performed by field emission scanning electron microscopy. The highest particle size and encapsulation efficiency of recovered nanoparticles were 248.37 nm and 91.16 % respectively. The recovered nanoparticles are spherical in nature and uniform in size. Developed nanoparticles have low crystallinity than the pure Nateglinide. The highest drug-polymer ratio formulation showed drug release 61.1 ± 1.76 % up to 24 h.

  2. Characterization of the polymer energy landscape in polymer:fullerene bulk heterojunctions with pure and mixed phases.

    PubMed

    Sweetnam, Sean; Graham, Kenneth R; Ngongang Ndjawa, Guy O; Heumüller, Thomas; Bartelt, Jonathan A; Burke, Timothy M; Li, Wentao; You, Wei; Amassian, Aram; McGehee, Michael D

    2014-10-08

    Theoretical and experimental studies suggest that energetic offsets between the charge transport energy levels in different morphological phases of polymer:fullerene bulk heterojunctions may improve charge separation and reduce recombination in polymer solar cells (PSCs). In this work, we use cyclic voltammetry, UV-vis absorption, and ultraviolet photoelectron spectroscopy to characterize hole energy levels in the polymer phases of polymer:fullerene bulk heterojunctions. We observe an energetic offset of up to 150 meV between amorphous and crystalline polymer due to bandgap widening associated primarily with changes in polymer conjugation length. We also observe an energetic offset of up to 350 meV associated with polymer:fullerene intermolecular interactions. The first effect has been widely observed, but the second effect is not always considered despite being larger in magnitude for some systems. These energy level shifts may play a major role in PSC performance and must be thoroughly characterized for a complete understanding of PSC function.

  3. Synthesis and characterization of aminated perfluoro polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Page-Belknap, Zachary Stephan Glenn

    Polymer electrolytes have been developed for use in anion exchange membrane fuel cells for years. However, due to the highly corrosive environment within these fuel cells, poor chemical stability of the polymers and low ion conductivity have led to high development costs and thus prevention from widespread commercialization. The work in this study aims to provide a solution to these problems through the synthesis and characterization of a novel polymer electrolyte. The 800 EW 3M PFSA sulfonyl fluoride precursor was aminated with 3-(dimethylamino)-1-propylamine to yield a functional polymer electrolyte following quaternization, referred to in this work as PFSa-PTMa. 1 M solutions of LiPF6, HCL, KOH, NaOH, CsOH, NaHCO3 and Na2CO3 were used to exchange the polymer to alternate counterion forms. Chemical structure analysis was performed using both FT and ATR infrared spectroscopy to confirm sulfonyl fluoride replacement and the absence of sulfonic acid sites. Mechanical testing of the polymer, following counterion exchange with KOH, at saturated conditions and 60 ºC exhibited a tensile strength of 13 +/- 2.0 MPa, a Young's modulus of 87 +/- 16 MPa and a degree of elongation reaching 75% +/- 9.1%, which indicated no mechanical degradation following exposure to a highly basic environment. Conductivities of the polymer in the Cl- and OH- counterion forms at saturated conditions and 90 ºC were observed at 26 +/- 8.0 mS cm-1 and 1.1 +/- 0.1 mS cm-1, respectively. OH- conductivities were slightly above those observed for CO32- and HCO 3- counterions at the same conditions, 0.63 +/- 0.18 and 0.66 +/- 0.21 mS cm-1 respectively. The ion exchange capacity (IEC) of the polymer in the Cl- counterion form was measured via titration at 0.57 meq g-1 which correlated to 11.2 +/- 0.10 water molecules per ion site when at 60ºC and 95% relative humidity. The IEC of the polymer in the OH- counterion form following titration expressed nearly negligible charge density, less than 0.01 meq

  4. Synthesis, characterization, and antiplasmodial activity of polymer-incorporated aminoquinolines.

    PubMed

    Aderibigbe, B A; Neuse, E W; Sadiku, E R; Ray, S Shina; Smith, P J

    2014-06-01

    In this research, aminoquinoline compounds were synthesized, characterized, and incorporated into water-soluble polymers to form conjugates. The conjugates were characterized by X-ray diffraction, thermal gravimetric analysis, scanning electron microscope, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy to confirm the successful incorporation of the aminoquinoline compound on to the polymer. The synthesized conjugates were screened for in vitro antiplasmodial activity in triplet test against chloroquine-sensitive strain of Plasmodium falciparum and chloroquine drug was used as a reference drug in all the experiments. A full dose-response was performed to determine the concentration inhibiting 50% of parasite growth (IC50 value). Polymeric conjugates containing 3-diethylamino-1-propylamine solubilizing units were found to be most active against the chloroquine-sensitive strain of P. falciparum.

  5. Cyano-Bridged Trimetallic Coordination Polymer Nanoparticles and Their Thermal Decomposition into Nanoporous Spinel Ferromagnetic Oxides.

    PubMed

    Zakaria, Mohamed B; Hossain, Md Shahriar A; Shiddiky, Muhammad J A; Shahabuddin, Mohammed; Yanmaz, Ekrem; Kim, Jung Ho; Belik, Alexei A; Ide, Yusuke; Hu, Ming; Tominaka, Satoshi; Yamauchi, Yusuke

    2016-10-10

    The synthesis of a novel family of cyano-bridged trimetallic coordination polymers (CPs) with various compositions and shapes has been reported by changing the compositional ratios of Fe, Co, and Ni species in the reaction system. In order to efficiently control the nucleation rate and the crystal growth, trisodium citrate dihydrate plays an important role as a chelating agent. After the obtained cyano-bridged trimetallic CPs undergo thermal treatment in air at three different temperatures (250, 350, and 450 °C), nanoporous spinel metal oxides are successfully obtained. Interestingly, the obtained nanoporous metal oxides are composed of small crstalline grains, and the grains are oriented in the same direction, realizing pseudo-single crystals with nanopores. The resultant nanoporous spinel oxides feature interesting magnetic properties. Cyano-bridged multimetallic CPs with various sizes and shapes can provide a pathway toward functional nanoporous metal oxides that are not attainable from simple cyano-bridged CPs containing single metal ions.

  6. A domain decomposition method for two-phase transport model in the cathode of a polymer electrolyte fuel cell

    NASA Astrophysics Data System (ADS)

    Sun, Pengtao; Xue, Guangri; Wang, Chao-yang; Xu, Jinchao

    2009-09-01

    Using Kirchhoff transformation, we develop a Dirichlet- Neumann alternating iterative domain decomposition method for a 2D steady-state two-phase model for the cathode of a polymer electrolyte fuel cell (PEFC) which contains a channel and a gas diffusion layer (GDL). This two-phase PEFC model is represented by a nonlinear coupled system which typically includes a modified Navier-Stokes equation with Darcy's drag as an additional source term of the momentum equation, and a convection-diffusion equation for the water concentration with discontinuous and degenerate diffusivity. For both cases of dry and wet gas channel, we employ Kirchhoff transformation and Dirichlet- Neumann alternating iteration with appropriate interfacial conditions on the GDL/channel interface to treat the jump nonlinearities in the water equation. Numerical experiments demonstrate that fast convergence as well as accurate numerical solutions are obtained simultaneously owing to the implementation of the above-described numerical techniques along with a combined finite element-upwind finite volume discretization to automatically control the dominant convection terms arising in the gas channel.

  7. Forced and free displacement characterization of ionic polymer transducers

    NASA Astrophysics Data System (ADS)

    Akle, Barbar J.; Duncan, Andrew; Akle, Etienne; Wallmersperger, Thomas; Leo, Donald J.

    2009-03-01

    Ionic polymer transducers (IPT), sometimes referred to as artificial muscles, are known to generate a large bending strain and a moderate stress at low applied voltages (<5V). Recently Akle and Leo[1] reported extensional actuation in ionic polymer transducers. In this study, extensional IPTs are characterized under forced and free displacement boundary condition as a function of transducer architecture. The electrode thickness is varied from 10 μm up to 40 μm while three extensional actuators with Lithium, Cesium, and tetraethylammonium (TEA) mobile cations are characterized. Three fixtures are built in order to characterize the extensional actuation response. The first fixture measures the free displacement of an IPT sample sandwiched between two aluminum plates glued using the electrically conductive silver paste. In the second fixture a spring is compressed against the test sample with variable amounts to generate different levels of pre-stress and prevents the bending of the IPT. In the third fixture dead weights are placed on top of the sample in order to prevent bending. In the spring loaded fixture a thermocouple is placed in the proximity of the actuator and temperature is measured. The different transducers are characterized using a step voltage input and an alternating current (AC) sine wave input. The step input resulted in a logarithmic rise like displacement curve, while the low frequency (<0.1 Hz) AC excitation generated a sine wave displacement response with a strong first harmonic. The high frequency AC excitation generated a response similar to that of the step input. Comparing the measured temperature for step and AC response demonstrated that the sample is heating up when exited with a high frequency signal; which is leading to the expansion of the sample. Initial experimental results demonstrate a strong correlation between electrode architecture and the peak strain response. Strains on the order of 2% are observed with air stable ionic

  8. Novel carbosilane containing polymers: Synthesis, characterization and applications

    NASA Astrophysics Data System (ADS)

    Wu, Zhizhong

    2004-12-01

    Cyclolinear carbosilane polymers with disilacyclobutane (DSCB) rings in the main chain structure were prepared by means of acyclic diene metathesis (ADMET) polymerization of the corresponding 1,3-dibutenyl-1,3-disilacyclobutanes. The copolymerization of a monomer of this type with a non-cyclic organosilane diene allowed for the incorporation of a varying number of DSCB rings into the polymer backbone. Subsequent hydrogenation of the double bonds with p-toluenesulfonhydrazide resulted in a saturated hydrocarbon structure in the main chain without affecting the DSCB ring. All of the resultant polymers are well-defined materials with a DSCB ring incorporated into the backbone structure, as evidenced by NMR spectroscopy and GPC analyses. The thermal behavior of these polymers was characterized by DSC and TGA. DSC indicated low Tgs and TGA evidenced high thermal stability in an inert atmosphere. In addition, large exothermic peaks were observed in the DSC, which indicated, along with the IR and Solid State 29Si NMR spectra, that crosslinking occurs during heating to ca. 250°C via opening of the imbedded DSCB rings. The dielectric constant of the dense, fully crosslinked polymer is quite low (2.37), which is substantially lower than that of any other known, non-fluorinated, non-porous, dielectric material. The dielectric constant of this material is also lower than the 2.6 effective dielectric constant value that is currently targeted for the next two generations of integrated circuits. Furthermore, we have found that the thermally induced crosslinking of this cyclolinear polycarbosilane is initiated at a considerably lower temperature (ca. 160°C) on a copper metal surface than on a Si or glass surface (ca. 250°C). This allows the selective coating of Cu by this electrically insulating, chemically inert, and thermally stable polymer, which has the potential for use as a dielectric material that will not require the use of a separate barrier layer to prevent Cu

  9. Characterization of a sustainable sulfur polymer concrete using activated fillers

    DOE PAGES

    Moon, Juhyuk; Kalb, Paul D.; Milian, Laurence; ...

    2016-01-02

    Sulfur polymer concrete (SPC) is a thermoplastic composite concrete consisting of chemically modified sulfur polymer and aggregates. This study focused on the characterization of a new SPC that has been developed as a sustainable construction material. It is made from industrial by-product sulfur that is modified with activated fillers of fly ash, petroleum refinery residual oil, and sand. Unlike conventional sulfur polymer cements made using dicyclopentadiene as a chemical modifier, the use of inexpensive industrial by-products enables the new SPC to cost-effectively produce sustainable, low-carbon, thermoplastic binder that can compete with conventional hydraulic cement concretes. A series of characterization analysesmore » was conducted including thermal analysis, X-ray diffraction, and spatially-resolved Xray absorption spectroscopy to confirm the polymerization of sulfur induced from the presence of the oil. In addition, mechanical testing, internal pore structure analysis, and scanning electron microscope studies evaluate the performance of this new SPC as a sustainable construction material with a reduced environmental impact.« less

  10. Characterization of a sustainable sulfur polymer concrete using activated fillers

    SciTech Connect

    Moon, Juhyuk; Kalb, Paul D.; Milian, Laurence; Northrup, Paul A.

    2016-01-02

    Sulfur polymer concrete (SPC) is a thermoplastic composite concrete consisting of chemically modified sulfur polymer and aggregates. This study focused on the characterization of a new SPC that has been developed as a sustainable construction material. It is made from industrial by-product sulfur that is modified with activated fillers of fly ash, petroleum refinery residual oil, and sand. Unlike conventional sulfur polymer cements made using dicyclopentadiene as a chemical modifier, the use of inexpensive industrial by-products enables the new SPC to cost-effectively produce sustainable, low-carbon, thermoplastic binder that can compete with conventional hydraulic cement concretes. A series of characterization analyses was conducted including thermal analysis, X-ray diffraction, and spatially-resolved Xray absorption spectroscopy to confirm the polymerization of sulfur induced from the presence of the oil. In addition, mechanical testing, internal pore structure analysis, and scanning electron microscope studies evaluate the performance of this new SPC as a sustainable construction material with a reduced environmental impact.

  11. Synthesis and characterization of polymers for light waveguide applications

    NASA Astrophysics Data System (ADS)

    Li, Bo

    The overall goal of this research was to prepare organo- soluble polymers that display low birefringence, low optical loss, and high thermal stability for use in light waveguide devices. Thus, two series of thermally stable polymers, i.e., aromatic polyimides and perfluorocyclobutane-containing poly(aryl ethers), were synthesized and characterized. The approach to the aromatic polyimides involved the synthesis of a new series of 4,4'-(9- fluorenylidene)dianilines containing large polarizable substituents. The diamines were polymerized with 2,2'-bis[4-(3,4- dicarboxyphenoxy)phenyl]propane dianhydride (BisA-DA) and 2,2'-bis(3,4- dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) in refluxing m-cresol containing a catalytic amount of isoquinoline. The polyimides were soluble in common organic solvents such as N-methyl-2- pyrrolidinone (NMP), tetrahydrofuran (THF), chloroform (CHCl3), and cyclopentanone and could be solution cast into tough films. Thin films of the new cardo polyimides displayed birefringences that ranged from -0.0042 to 0.0074. In the second part of this work, a series of new difunctional and trifunctional trifluorovinylether-containing monomers was synthesized and polymerized via the thermal cyclodimerization of the vinyl groups. The number of carbon-hydrogen bonds was minimized in these systems in order to minimize the optical loss. A tough, transparent film was made from a polymer prepared from a trifunctional monomer, 1,1,1- trifluoro-2,2,2-tris(4-trifluorovinyloxyphenyl)ethane, which had a birefringence of 0.0008. The film showed negligible absorption at 1550 nm in the near-IR region. The polymer was also very thermally stable. Most of the linear polymers were soluble in common organic solvents such as NMP, THF, chloroform and cyclopentanone and could be solution cast into thin films, which displayed birefringences that ranged from -0.0005 to 0.0048.

  12. Characterization of biodegradable polymers irradiated with swift heavy ions

    NASA Astrophysics Data System (ADS)

    Salguero, N. G.; del Grosso, M. F.; Durán, H.; Peruzzo, P. J.; Amalvy, J. I.; Arbeitman, C. R.; García Bermúdez, G.

    2012-02-01

    In view of their application as biomaterials, there is an increasing interest in developing new methods to induce controlled cell adhesion onto polymeric materials. The critical step in all these methods involves the modification of polymer surfaces, to induce cell adhesion, without changing theirs degradation and biocompatibility properties. In this work two biodegradable polymers, polyhydroxybutyrate (PHB) and poly- L-lactide acid (PLLA) were irradiated using carbon and sulfur beams with different energies and fluences. Pristine and irradiated samples were degradated by immersion in a phosphate buffer at pH 7.0 and then characterized. The analysis after irradiation and degradation showed a decrease in the contact angle values and changes in their crystallinity properties.

  13. Synthesis and characterization of macromolecular layers grafted to polymer surfaces

    NASA Astrophysics Data System (ADS)

    Burtovyy, Oleksandr

    The composition and behavior of surfaces and interfaces play a pivotal role in dictating the overall efficiency of the majority of polymeric materials and devices. Surface properties of the materials can be altered using surface modification techniques. It is necessary to highlight that successful methods of surface modification should affect only the upper layer of the polymer material without changing bulk properties. The processes must introduce new functionalities to the surface, optimize surface roughness, lubrication, hydrophobicity, hydrophilicity, adhesion, conductivity, and/or biocompatibility. Research presented in this dissertation is dedicated to the synthesis, characterization, and application of thin macromolecular layers anchored to polymer substrates. Specifically, attachment of functional polymers via a "grafting to" approach has been extensively studied using PET and nylon model substrates. First, poly(glycidyl methacrylate) was used to introduce permanent functionalities to the model substrates by anchoring it to model films. Then, three different functional polymers were grafted on top of the previous layer. As one part of this study, the temperature and time dependence of grafting functional layers were studied. The surface coverage by hydrophobic polymer was determined from experimental data and predicted by a model. In general, the model has a high degree of predictive capability. Next, surface modification of polymeric fibers and membranes is presented as an important application of the polymer thin layers targeted in the study. Specifically, the procedures developed for surface modification of model substrates was employed for modification of PET, nylon, and cotton fabrics as well as PET track-etched membranes. Since epoxy groups are highly reactive in various chemical reactions, the approach becomes virtually universal, allowing both various surfaces and end-functionalized macromolecules to be used in the grafted layer synthesis. PET

  14. Synthesis and Characterization of Polymer-Templated Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Tamakloe, Beatrice

    This research reports on the investigation into the synthesis and stabilization of iron oxide nanoparticles for theranostic applications using amine-epoxide polymers. Although theranostic agents such as magnetic nanoparticles have been designed and developed for a few decades, there is still more work that needs to be done with the type of materials that can be used to stabilize or functionalize these particles if they are to be used for applications such as drug delivery, imaging and hyperthermia. For in-vivo applications, it is crucial that organic coatings enclose the nanoparticles in order to prevent aggregation and facilitate efficient removal from the body as well as protect the body from toxic material. The objective of this thesis is to design polymer coated magnetite nanoparticles with polymers that are biocompatible and can stabilize the iron oxide nanoparticle to help create mono-dispersed particles in solution. It is desirable to also have these nanoparticles possess high magnetic susceptibility in response to an applied magnetic field. The co-precipitation method was selected because it is probably the simplest and most efficient chemical pathway to obtain magnetic nanoparticles. In literature, cationic polymers such as Polyethylenimine (PEI), which is the industry standard, have been used to stabilize IONPs because they can be used in magnetofections to deliver DNA or RNA. PEI however is known to interact very strongly with proteins and is cytotoxic, so as mentioned previously the Iron Oxide nanoparticles (IONPs) synthesized in this study were stabilized with amine-epoxide polymers because of the limitations of PEI. Four different amine-epoxide polymers which have good water solubility, biodegradability and less toxic than PEI were synthesized and used in the synthesis and stabilization of the magnetic nanoparticles and compared to PEI templated IONPs. These polymer-templated magnetic nanoparticles were also characterized by size, surface charge, Iron

  15. Mechanical characterization of low dimensional nanomaterials and polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Gao, Hongsheng

    This research was aimed to characterize the mechanical properties of low dimensional nanomaterials and polymer nanocomposites, and to study the reinforcing mechanisms of nanoscale reinforcements. The nanomaterials studied were zero-dimensional nanomaterial--cuprous oxide (Cu2O) nanocubes, one-dimensional nanomaterials--silver nanowires and silicon oxide (SiO2) nanowires, and two-dimensional nanomaterial--nanometer-thick montmorillonite clay platelets. The hardness and elastic moduli of solid Cu 2O nanocubes and silver nanowires were measured by directly indenting individual cubes/wires using a nanoindenter. The elastic modulus of amorphous SiO2 nanowires was measured by performing three-point bending on suspended wires with an atomic force microscope (AFM) tip. The elastic modulus of the nanometer-thick clay platelets was assessed by the modulus mapping technique. An array of nanoscale indents was successfully made on a nanowire. The nanowires were cut to the length as needed. The nanoindentation approach permits the direct machining of individual nanowires without complications of conventional lithography. The nanomechanical properties of single-walled carbon nanotube (SWCNT)-reinforced epoxy composites with varying nanotube concentrations were measured by nanoindentation/nanoscratch techniques. Hardness and elastic modulus were measured using a nanoindenter. Viscoelastic properties of the nanocomposites were measured using nanoindentation dynamic mechanical analysis tests. The SWCNT reinforcing mechanisms were further studied by both Halpin-Tsai and Mori-Tanaka theories, which were found applicable to SWCNT-reinforced, amorphous-polymer composites. The possible reinforcing mechanisms that work in polymer-SWCNT composites and reasons responsible for SWCNTs' low mechanical reinforcement were analyzed. Nanoclay-reinforced agarose nanocomposites with varying clay concentrations were structurally and mechanically characterized. Structural characterization was carried

  16. Fabrication and characterization of solid-state, conducting polymer actuators

    SciTech Connect

    Xie, J.; Sansinena, J. M.; Gao, J.; Wang, H. L.

    2004-01-01

    We report here the fabrication and characterization of solid-state, conducting polymer actuators. The electrochemical activity of polyaniline (PANI) thin film coated with solid-state polyelectrolyte is very similar to the polyaniline thin film in an aqueous solution. The solid-state actuator is adhere to a lever arm of an force transducer and the force generation is measured in real time. The force generated by the actuator is found to be length dependent. However, the overall torques generated by the actuators with different lengths remains essentially the same. The effect of stimulation signals such as voltage, current, on the bending angle and displacement is also studied using square wave potential.

  17. Evaluation and characterization of the methane-carbon dioxide decomposition reaction

    NASA Technical Reports Server (NTRS)

    Davenport, R. J.; Schubert, F. H.; Shumar, J. W.; Steenson, T. S.

    1975-01-01

    A program was conducted to evaluate and characterize the carbon dioxide-methane (CO2-CH4) decomposition reaction, i.e., CO2 + CH4 = 2C + 2H2O. The primary objective was to determine the feasibility of applying this reaction at low temperatures as a technique for recovering the oxygen (O2) remaining in the CO2 which exits mixed with CH4 from a Sabatier CO2 reduction subsystem (as part of an air revitalization system of a manned spacecraft). A test unit was designed, fabricated, and assembled for characterizing the performance of various catalysts for the reaction and ultraviolet activation of the CH4 and CO2. The reactor included in the test unit was designed to have sufficient capacity to evaluate catalyst charges of up to 76 g (0.17 lb). The test stand contained the necessary instrumentation and controls to obtain the data required to characterize the performance of the catalysts and sensitizers tested: flow control and measurement, temperature control and measurement, product and inlet gas analysis, and pressure measurement. A product assurance program was performed implementing the concepts of quality control and safety into the program effort.

  18. Synthesis and characterization of carbon nanotube-polymer multilayer structures.

    PubMed

    Misra, Abha; Raney, Jordan R; De Nardo, Luigi; Craig, Anna E; Daraio, Chiara

    2011-10-25

    We develop lightweight, multilayer materials composed of alternating layers of poly dimethyl siloxane (PDMS) polymer and vertically aligned carbon nanotube (CNT) arrays, and characterize their mechanical response in compression. The CNT arrays used in the assembly are synthesized with graded mechanical properties along their thickness, and their use enables the creation of multilayer structures with low density (0.12-0.28 g/cm(3)). We test the mechanical response of structures composed of different numbers of CNT layers partially embedded in PDMS polymer, under quasi-static and dynamic loading. The resulting materials exhibit a hierarchical, fibrous structure with unique mechanical properties: They can sustain large compressive deformations (up to ∼0.8 strain) with a nearly complete recovery and present strain localization in selected sections of the materials. Energy absorption, as determined by the hysteresis observed in stress-strain curves, is found to be at least 3 orders of magnitude larger than that of natural and synthetic cellular materials of comparable density. Conductive bucky paper is included within the polymer interlayers. This allows the measurement of resistance variation as a function of applied stress, showing strong correlation with the observed strain localization in compression.

  19. Replacement of silicone polymer A with silicone polymer B and the subsequent characterization of the new cellular silicone materials

    SciTech Connect

    Schneider, J.W.

    1994-04-01

    The purpose of this project is to replace silicone polymer A with silicone polymer B produced by Vendor B. Silicone polymer B and the resulting B-50 cellular silicone have been used to produce cushions for the W87 program. Approximately 5.5 years of stress relaxation aging study data as well as actual part surveillance data have been collected, characterizing the stockpile life performance of the B-50 cellular silicone cushion material. Process characterization of new cellular silicone materials as a result of replacing silicone polymer A with silicone polymer B has been completed. Load deflection requirements for the new cellular silicone materials based on silicone polymer B have been met. The silicone polymer B based cellular silicone materials must be compounded at densities of approximately 0.03 g/cm{sup 3} less than the silicone polymer A based cellular silicone materials in order to achieve the same load deflection requirements has also been demonstrated. The change in silicone polymers from A to B involved a decrease in volatile content as well as a decrease in part shrinkage.

  20. Characterization of Nonlinear Rate Dependent Response of Shape Memory Polymers

    NASA Technical Reports Server (NTRS)

    Volk, Brent; Lagoudas, Dimitris C.; Chen, Yi-Chao; Whitley, Karen S.

    2007-01-01

    Shape Memory Polymers (SMPs) are a class of polymers, which can undergo deformation in a flexible state at elevated temperatures, and when cooled below the glass transition temperature, while retaining their deformed shape, will enter and remain in a rigid state. Upon heating above the glass transition temperature, the shape memory polymer will return to its original, unaltered shape. SMPs have been reported to recover strains of over 400%. It is important to understand the stress and strain recovery behavior of SMPs to better develop constitutive models which predict material behavior. Initial modeling efforts did not account for large deformations beyond 25% strain. However, a model under current development is capable of describing large deformations of the material. This model considers the coexisting active (rubber) and frozen (glass) phases of the polymer, as well as the transitions between the material phases. The constitutive equations at the continuum level are established with internal state variables to describe the microstructural changes associated with the phase transitions. For small deformations, the model reduces to a linear model that agrees with those reported in the literature. Thermomechanical characterization is necessary for the development, calibration, and validation of a constitutive model. The experimental data reported in this paper will assist in model development by providing a better understanding of the stress and strain recovery behavior of the material. This paper presents the testing techniques used to characterize the thermomechanical material properties of a shape memory polymer (SMP) and also presents the resulting data. An innovative visual-photographic apparatus, known as a Vision Image Correlation (VIC) system was used to measure the strain. The details of this technique will also be presented in this paper. A series of tensile tests were performed on specimens such that strain levels of 10, 25, 50, and 100% were applied to

  1. Synthesis, physical and electrical characterization of polymer electrolytes and polymer complexes containing polyhalides

    SciTech Connect

    Tipton, A.L.

    1992-01-01

    The conductivity and dielectric response was determined for poly (propylene oxide) (PPO), the polymeric solid electrolytes (PPO)[sub 8]NH[sub 4]SO[sub 3]CF[sub 3], (PPO)[sub 16]NaI, (PPO)[sub 10]NaI and (PPO)[sub 8]NaI and the sodium polyiodide complex, (PPO)[sub 8]NaI[sub 9], in the frequency range from dc to 6 GHz and the temperature range from 173-323 K at 3 GHz. These data were used to make the first comparisons between an amorphous host polymer and its salt complexes. The addition of salt to PPO results in a considerable change in dielectric properties. The dielectric loss spectrum of PPO displays a broad [beta]-relaxation attributed to the micro-Brownian motion of the polymer while no appreciable relaxation peak is observed for (PPO)[sub 8]NH[sub 4]SO[sub 3]CF[sub 3]. The conductivity of the previously characterized (PEO)[sub 8]NH[sub 4]SO[sub 3]CF[sub 3] is higher than (PPO)[sub 8]NH[sub 4]SO[sub 3]CF[sub 3] over the entire frequency range covered. The methyl group on PPO apparently sterically restricts the local motions of the polymer necessary for ion conduction. The dielectric loss spectrum of (PPO)[sub 8]NaI displays a narrow relaxation peak around 10 MHz, possibly associated with the motions of NaI aggregates. (PPO)[sub 8]NaI[sub 9] displays a much higher conductivity than simple polymer-salt complexes. The lack of frequency dependence of the (PPO)[sub 8]NaI[sub 9] conductivity compared to that of the simple polymer-salt complexes suggests that long range charge transport in (PPO)[sub 8]NaI[sub 9] is dominated by a process that is much faster than the diffusion of ions in the polymer solvent. Resonance Raman spectra reveal the presence of a rich variety of polyhalide species in the products resulting from the addition of Br[sub 2], IBr or I[sub 2] to PPO-LiBr or PPO-LiI salt complexes. Impedance measurements demonstrate high bulk conductivities. There appears to be little correlation between conductivity and iodine or bromine content.

  2. Characterization and degradation studies on synthetic polymers for aerospace application

    NASA Technical Reports Server (NTRS)

    Hsu, M. T. S.

    1982-01-01

    The anti-misting additive for jet fuels known as FM-9 (proprietary polymer) was characterized by elemental analysis, solubility studies and molecular weight determination. Physical properties of surface tension, viscosity, specific gravity and other physical parameters were determined. These results are compared with properties of polyisobutylene and fuels modified with the same; the misting characteristics of polyisobutylene and FM-9 in Jet A fuel are included. Characterization and degradation of phthalocyanine and its derivatives were accomplished by use of a mass spectrometer and a pyroprobe solid pyrolyzer. Metal phthalocyanine tetracarboxylic acids and phthalocyanine-tetraamine cured epoxies were studied. Epoxy/graphite composite panels were exposed to a NASA-Ames radiant panel fire simulator in the flaming and non-flaming modes; toxic gases of HCN and HZS were measured along with oxygen, Co2, Co, and organic gases.

  3. Characterization of novel soybean-oil-based thermosensitive amphiphilic polymers for drug delivery applications

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Characterization, aggregation behavior, physical properties and drug-polymer interaction of novel soybean oil-based polymers i.e., hydrolyzed polymers of (epoxidized) soybean oil (HPESO), were studied. The surface tension method was used to determine the critical micelle concentration (CMC). CMC w...

  4. Empirical mode decomposition of digital mammograms for the statistical based characterization of architectural distortion.

    PubMed

    Zyout, Imad; Togneri, Roberto

    2015-01-01

    Among the different and common mammographic signs of the early-stage breast cancer, the architectural distortion is the most difficult to be identified. In this paper, we propose a new multiscale statistical texture analysis to characterize the presence of architectural distortion by distinguishing between textural patterns of architectural distortion and normal breast parenchyma. The proposed approach, firstly, applies the bidimensional empirical mode decomposition algorithm to decompose each mammographic region of interest into a set of adaptive and data-driven two-dimensional intrinsic mode functions (IMF) layers that capture details or high-frequency oscillations of the input image. Then, a model-based approach is applied to IMF histograms to acquire the first order statistics. The normalized entropy measure is also computed from each IMF and used as a complementary textural feature for the recognition of architectural distortion patterns. For evaluating the proposed AD characterization approach, we used a mammographic dataset of 187 true positive regions (i.e. depicting architectural distortion) and 887 true negative (normal parenchyma) regions, extracted from the DDSM database. Using the proposed multiscale textural features and the nonlinear support vector machine classifier, the best classification performance, in terms of the area under the receiver operating characteristic curve (or Az value), achieved was 0.88.

  5. A characterization of the two-step reaction mechanism of phenol decomposition by a Fenton reaction

    NASA Astrophysics Data System (ADS)

    Valdés, Cristian; Alzate-Morales, Jans; Osorio, Edison; Villaseñor, Jorge; Navarro-Retamal, Carlos

    2015-11-01

    Phenol is one of the worst contaminants at date, and its degradation has been a crucial task over years. Here, the decomposition process of phenol, in a Fenton reaction, is described. Using scavengers, it was observed that decomposition of phenol was mainly influenced by production of hydroxyl radicals. Experimental and theoretical activation energies (Ea) for phenol oxidation intermediates were calculated. According to these Ea, phenol decomposition is a two-step reaction mechanism mediated predominantly by hydroxyl radicals, producing a decomposition yield order given as hydroquinone > catechol > resorcinol. Furthermore, traces of reaction derived acids were detected by HPLC and GS-MS.

  6. Fire-safe polymers and polymer composites

    NASA Astrophysics Data System (ADS)

    Zhang, Huiqing

    The intrinsic relationships between polymer structure, composition and fire behavior have been explored to develop new fire-safe polymeric materials. Different experimental techniques, especially three milligram-scale methods---pyrolysis-combustion flow calorimetry (PCFC), simultaneous thermal analysis (STA) and pyrolysis GC/MS---have been combined to fully characterize the thermal decomposition and flammability of polymers and polymer composites. Thermal stability, mass loss rate, char yield and properties of decomposition volatiles were found to be the most important parameters in determining polymer flammability. Most polymers decompose by either an unzipping or a random chain scission mechanism with an endothermic decomposition of 100--900 J/g. Aromatic or heteroaromatic rings, conjugated double or triple bonds and heteroatoms such as halogens, N, O, S, P and Si are the basic structural units for fire-resistant polymers. The flammability of polymers can also be successfully estimated by combining pyrolysis GC/MS results or chemical structures with TGA results. The thermal decomposition and flammability of two groups of inherently fire-resistant polymers---poly(hydroxyamide) (PHA) and its derivatives, and bisphenol C (BPC II) polyarylates---have been systematically studied. PHA and most of its derivatives have extremely low heat release rates and very high char yields upon combustion. PHA and its halogen derivatives can completely cyclize into quasi-polybenzoxazole (PBO) structures at low temperatures. However, the methoxy and phosphate derivatives show a very different behavior during decomposition and combustion. Molecular modeling shows that the formation of an enol intermediate is the rate-determining step in the thermal cyclization of PHA. BPC II-polyarylate is another extremely flame-resistant polymer. It can be used as an efficient flame-retardant agent in copolymers and blends. From PCFC results, the total heat of combustion of these copolymers or blends

  7. Characterization of a sucrose/starch matrix through positron annihilation lifetime spectroscopy: unravelling the decomposition and glass transition processes.

    PubMed

    Sharma, Sandeep Kumar; Roudaut, Gaëlle; Fabing, Isabelle; Duplâtre, Gilles

    2010-11-14

    The triplet state of positronium, o-Ps, is used as a probe to characterize a starch-20% w/w sucrose matrix as a function of temperature (T). A two-step decomposition (of sucrose, and then starch) starts at 440 K as shown by a decrease in the o-Ps intensity (I(3)) and lifetime (τ(3)), the latter also disclosing the occurrence of a glass transition. Upon sucrose decomposition, the matrix acquires properties (reduced size and density of nanoholes) that are different from those of pure starch. A model is successfully established, describing the variations of both I(3) and τ(3) with T and yields a glass transition temperature, T(g) = (446 ± 2) K, in spite of the concomitant sucrose decomposition. Unexpectedly, the starch volume fraction (as probed through thermal gravimetry) decreases with T at a higher rate than the free volume fraction (as probed through PALS).

  8. Cyclic voltammetry characterization of metal complex imprinted polymer.

    PubMed

    Zeng, Yi Ning; Zheng, Ning; Osborne, Peter G; Li, Yuan Zong; Chang, Wen Bao; Wen, Mei Juan

    2002-01-01

    Polymer capable of specific binding to Cu(2+)-2, 2'-dipyridyl complex was prepared by molecular imprinting technology. The binding specificity of the polymer to the template (Cu(2+)-2, 2'-dipyridyl complex) was investigated by cyclic voltammetric scanning using the carbon paste electrode modified by polymer particles in phosphate buffer solution. Factors that influence rebinding of the imprinted polymer were explored. The results demonstrated that cyclic voltammetry was an efficient approach to explore interactions between template and imprinted polymers.

  9. Choosing the optimal mother wavelet for decomposition of radio-frequency intravascular ultrasound data for characterization of atherosclerotic plaque lesions

    NASA Astrophysics Data System (ADS)

    Bedekar, Devyani; Nair, Anuja; Vince, D. Geoffrey

    2005-04-01

    Aim: The objective of this work is to determine the optimal basis function to perform wavelet analysis for tissue characterization of radio frequency intravascular ultrasound (IVUS) backscattered data. This is the most important step in wavelet analysis as it ensures accurate decomposition of the original signal into the various frequency bands. The criterion to choose the mother wavelet that is best suited to the data depends on the intended application. Wavelet families possessing properties like orthogonality, regularity, stability and admissibility have previously been shown to have application in tissue characterization. Algorithm: Depending on the usable data bandwidth known from previous studies we decomposed data using a 4-level decomposition scheme. We then calculated Shannon"s entropy for every level and employed "minimum Shannon entropy criterion" to determine the best mother wavelet for signal decomposition. According to this criterion, accurate decomposition is indicated when the total entropy of the daughter (decomposed) levels is lower than the entropy of the parent level. Analysis and Results: We acquired 40 MHz IVUS data ex-vivo from 10 left anterior descending (LAD) coronary arteries. Data was acquired such that each frame comprised of 256 scanlines. Next, we randomly selected 3 scanlines for each LAD and applied the above-mentioned Shannon entropy criterion for these 30 scanlines. We analyzed 23 mother wavelets from different families. Daubechies 3rd order wavelet accurately decomposes 29/30 scanlines at all levels. Daubechies 6th order wavelet appears optimal for 21/30 scanlines. Future direction: To obtain more precise signal decomposition, the optimal mother wavelet should be selected at every decomposition level. The best mother wavelet is indicated by the lowest Shannon entropy for that particular level.

  10. Ozone decomposition.

    PubMed

    Batakliev, Todor; Georgiev, Vladimir; Anachkov, Metody; Rakovsky, Slavcho; Zaikov, Gennadi E

    2014-06-01

    Catalytic ozone decomposition is of great significance because ozone is a toxic substance commonly found or generated in human environments (aircraft cabins, offices with photocopiers, laser printers, sterilizers). Considerable work has been done on ozone decomposition reported in the literature. This review provides a comprehensive summary of the literature, concentrating on analysis of the physico-chemical properties, synthesis and catalytic decomposition of ozone. This is supplemented by a review on kinetics and catalyst characterization which ties together the previously reported results. Noble metals and oxides of transition metals have been found to be the most active substances for ozone decomposition. The high price of precious metals stimulated the use of metal oxide catalysts and particularly the catalysts based on manganese oxide. It has been determined that the kinetics of ozone decomposition is of first order importance. A mechanism of the reaction of catalytic ozone decomposition is discussed, based on detailed spectroscopic investigations of the catalytic surface, showing the existence of peroxide and superoxide surface intermediates.

  11. Ozone decomposition

    PubMed Central

    Batakliev, Todor; Georgiev, Vladimir; Anachkov, Metody; Rakovsky, Slavcho

    2014-01-01

    Catalytic ozone decomposition is of great significance because ozone is a toxic substance commonly found or generated in human environments (aircraft cabins, offices with photocopiers, laser printers, sterilizers). Considerable work has been done on ozone decomposition reported in the literature. This review provides a comprehensive summary of the literature, concentrating on analysis of the physico-chemical properties, synthesis and catalytic decomposition of ozone. This is supplemented by a review on kinetics and catalyst characterization which ties together the previously reported results. Noble metals and oxides of transition metals have been found to be the most active substances for ozone decomposition. The high price of precious metals stimulated the use of metal oxide catalysts and particularly the catalysts based on manganese oxide. It has been determined that the kinetics of ozone decomposition is of first order importance. A mechanism of the reaction of catalytic ozone decomposition is discussed, based on detailed spectroscopic investigations of the catalytic surface, showing the existence of peroxide and superoxide surface intermediates. PMID:26109880

  12. Characterization of Solid Polymers, Ceramic Gap Filler, and Closed-Cell Polymer Foam Using Low-Load Test Methods

    NASA Technical Reports Server (NTRS)

    Herring, Helen M.

    2008-01-01

    Various solid polymers, polymer-based composites, and closed-cell polymer foam are being characterized to determine their mechanical properties, using low-load test methods. The residual mechanical properties of these materials after environmental exposure or extreme usage conditions determines their value in aerospace structural applications. In this experimental study, four separate polymers were evaluated to measure their individual mechanical responses after thermal aging and moisture exposure by dynamic mechanical analysis. A ceramic gap filler, used in the gaps between the tiles on the Space Shuttle, was also tested, using dynamic mechanical analysis to determine material property limits during flight. Closed-cell polymer foam, used for the Space Shuttle External Tank insulation, was tested under low load levels to evaluate how the foam's mechanical properties are affected by various loading and unloading scenarios.

  13. Characterization of Hyaluronan-Protein Microstructures and Polymer Solutions

    NASA Astrophysics Data System (ADS)

    Curtis, J. E.; McLane, L.; Bedoya, M.; Beatty, R.; Kramer, A.; Boehm, H.; Scrimgeour, J.

    2010-03-01

    Evidence is mounting that mechanical and topographical features of biomaterials can be as critical for cellular behavior as chemical properties. A case in point is hyaluronan (HA), a large polysaccharide with unique mechanical and hydrodynamic properties, found in many tissues and bodily fluids. Thanks to a large variety of accessible conformations and aggregation states, this remarkable polymer can impart on its biological environment a diverse range of structural and viscoelastic properties with far-reaching consequences for cell physiology (migration, inflammation, cancer). Supramolecular assembly of HA is typically mediated by HA-binding proteins. These specialized molecules are known to assist the formation of organized structures, such as cross-linked bundles, gels, or the all-important pericellular coat, a polymer network anchored to many cell surfaces. Precisely how the material properties of HA-rich matrices and aggregates are modified by the associated proteins, however, is largely a matter of speculation. We will present new insights concerning the cell coat and HA-protein solutions characterized using passive microrheology, fluorescence recovery after photobleaching (FRAP), and optical force probe microscopy.

  14. Synthetic organo- and polymer- clays : preparation, characterization, and materials applications.

    SciTech Connect

    Carrado, K. A.; Chemistry

    2000-01-01

    We have over the years developed and patented a general technique for the hydrothermal synthesis of clay minerals in the presence of organic, organometallic, and polymeric intercalants. This review will summarize the details for crystallization of modified hectorites along with their characterization and materials applications. Among the several potential uses of these synthetic materials, there are two important applications concerning catalysis and composites. The fate of the template dictates which of these applications is pertinent. First, if the organic molecule or polymer is used with the intention of acting as templates of pore structure, then the organic template is removed after the modified clay has been crystallized. Upon template removal, the now porous materials are examined for their use as potential catalysts and catalyst supports. We have recently proven a correlation between catalyst pore size in the mesoporous range and the size and concentration of a polymeric template that is used. Preliminary hydrodesulfurization catalytic results have been obtained using these materials. If, on the other hand, intercalants are allowed to remain as a part of the structure, then a distinctive class of organic-inorganic composites becomes possible. When polymeric intercalants are used, especially at high concentrations, the materials have relevance to nanocomposite applications. Work in this area has focused on incorporating polymers at higher than 85 wt.% of the nanocomposite.

  15. Preparation and characterization of conducting polymer/silver hexacyanoferrate nanocomposite

    NASA Astrophysics Data System (ADS)

    de Azevedo, W. M.; de Mattos, I. L.; Navarro, M.; da Silva, E. F., Jr.

    2008-11-01

    In this work, we present an alternative route to prepare silver hexacyanoferrate(II)/polyaniline (PANI) composite thin films. Differently from the electrochemical method, used to synthesize the conducting polymer film on a electrode surface, this new chemical route makes use of dialysis membrane as a solid support to synthesize the silver hexacyanoferrate(III) compound, and subsequently uses this composite membrane as oxidizing agent to polymerize the aniline monomer. The spectroscopic (UV-vis and IR region) and electrochemical characterization (cyclic voltammetry) indicates that the polymeric composite remains optically active and conductive. The X-ray analysis shows that the composite membrane/Ag 3[Fe III(CN) 6] has an crystalline structure that can be assigned to the Ag 3[Fe III(CN) 6] structure, and after reaction with aniline solution it became less crystalline. Additionally the SEM measurements shown that the reaction of silver ions with hexacyanoferrate(III) across the membrane results in a well defined and aliened Ag 3[Fe III(CN) 6] crystals and when this crystalline compound reacts with aniline monomer silver wire of 100 nm of diameter by 6 μm longer are formed together with the conducting polymer polyaniline/Ag x[Fe II(CN) 6] composite.

  16. Characterization of a polymer-infiltrated ceramic-network material

    PubMed Central

    Corazza, Pedro H.; Zhang, Yu

    2015-01-01

    Objectives To characterize the microstructure and determine some mechanical properties of a polymer-ingfiltrated ceramic-network (PICN) material (Vita Enamic, Vita Zahnfabrik) available for CAD–CAM systems. Methods Specimens were fabricated to perform quantitative and qualitative analyses of the material’s microstructure and to determine the fracture toughness (KIc), density (ρ), Poisson’s ratio (v) and Young’s modulus (E). KIc was determined using V-notched specimens and the short beam toughness method, where bar-shaped specimens were notched and 3-point loaded to fracture. ρ was calculated using Archimedes principle, and v and E were measured using an ultrasonic thickness gauge with a combination of a pulse generator and an oscilloscope. Results Microstructural analyses showed a ceramic- and a polymer-based interpenetrating network. Mean and standard deviation values for the properties evaluated were: KIc = 1.09 ± 0.05 MPa m1/2, ρ = 2.09 ± 0.01 g/cm3, v = 0.23 ± 0.002 and E = 37.95 ± 0.34 GPa. Significance The PICN material showed mechanical properties between porcelains and resin-based composites, reflecting its microstructural components. PMID:24656471

  17. Production and Characterization of a Polymer from Arthrobacter sp

    PubMed Central

    Bodie, Elizabeth A.; Schwartz, Robert D.; Catena, Anthony

    1985-01-01

    An Arthrobacter sp. isolated from a glucose-sucrose agar plate was found to produce a neutral, extremely viscous, opalescent extracellular polymer. Growth, polymer production, and rheological properties and chemical composition of the isolated polymer were examined. The polymer was found to be substantially different from other arthrobacter polymers. Some unusual properties included irreversible loss of viscosity with high temperature and degradation of the polymer during fermentation and upon storage at 4°C. Other characteristics included dependence on sucrose for polymer production, relative pH stability, increased viscosity with increased salt concentration, and pseudoplasticity. The polymer was found to be composed primarily (if not entirely) of d-fructose. The fructose content and other characteristics suggested that the polymer was a levan. PMID:16346883

  18. Strain-dependent characterization of electrode and polymer network of electrically activated polymer actuators

    NASA Astrophysics Data System (ADS)

    Töpper, Tino; Osmani, Bekim; Weiss, Florian M.; Winterhalter, Carla; Wohlfender, Fabian; Leung, Vanessa; Müller, Bert

    2015-04-01

    Fecal incontinence describes the involuntary loss of bowel content and affects about 45 % of retirement home residents and overall more than 12 % of the adult population. Artificial sphincter implants for treating incontinence are currently based on mechanical systems with failure rates resulting in revision after three to five years. To overcome this drawback, artificial muscle sphincters based on bio-mimetic electro-active polymer (EAP) actuators are under development. Such implants require polymer films that are nanometer-thin, allowing actuation below 24 V, and electrodes that are stretchable, remaining conductive at strains of about 10 %. Strain-dependent resistivity measurements reveal an enhanced conductivity of 10 nm compared to 30 nm sputtered Au on silicone for strains higher than 5 %. Thus, strain-dependent morphology characterization with optical microscopy and atomic force microscopy could demonstrate these phenomena. Cantilever bending measurements are utilized to determine elastic/viscoelastic properties of the EAP films as well as their long-term actuation behavior. Controlling these properties enables the adjustment of growth parameters of nanometer-thin EAP actuators.

  19. Use of nakagami statistics and empirical mode decomposition for ultrasound tissue characterization by a nonfocused transducer.

    PubMed

    Tsui, Po-Hsiang; Chang, Chien-Cheng; Ho, Ming-Chih; Lee, Yu-Hsin; Chen, Yung-Sheng; Chang, Chien-Chung; Huang, Norden E; Wu, Zhao-Hua; Chang, King-Jen

    2009-12-01

    The Nakagami parameter associated with the Nakagami distribution estimated from ultrasonic backscattered signals reflects the scatterer concentration in a tissue. A nonfocused transducer does not allow tissue characterization based on the Nakagami parameter. This paper proposes a new method called the noise-assisted Nakagami parameter based on empirical mode decomposition of noisy backscattered echoes to allow quantification of the scatterer concentration based on data obtained using a nonfocused transducer. To explore the practical feasibility of the proposed method, the current study performed experiments on phantoms and measurements on rat livers in vitro with and without fibrosis induction. The results show that using a nonfocused transducer makes it possible to use the noise-assisted Nakagami parameter to classify phantoms with different scatterer concentrations and different stages of liver fibrosis in rats more accurately than when using techniques based on the echo intensity and the conventional Nakagami parameter. However, the conventional Nakagami parameter and the noise-assisted Nakagami parameter have different meanings: the former represents the statistics of signals backscattered from unresolvable scatterers, whereas the latter is associated with stronger resolvable scatterers or local inhomogeneity caused by scatterer aggregation.

  20. Synthesis and characterization of triglyceride based thermosetting polymers

    NASA Astrophysics Data System (ADS)

    Can, Erde

    2005-07-01

    Plant oils, which are found in abundance in all parts of the world and are easily replenished annually, have the potential to replace petroleum as a chemical feedstock for making polymers. Within the past few years, there has been growing interest to use triglycerides as the basic constituent of thermosetting polymers with the necessary rigidity, strength and glass transition temperatures required for engineering applications. Plant oils are not polymerizable in their natural form, however various functional groups that can polymerize can easily be attached to the triglyceride structure making them ideal cross-linking monomers for thermosetting liquid molding resins. Through this research project a number of thermosetting liquid molding resins based on soybean and castor oil, which is a specialty oil with hydroxyls on its fatty acids, have been developed. The triglyceride based monomers were prepared via the malination of the alcoholysis products of soybean and castor oil with various polyols, such as pentaerythritol, glycerol, and Bisphenol A propoxylate. The malinated glycerides were then cured in the presence of a reactive diluent, such as styrene, to form rigid glassy materials with a wide range of properties. In addition to maleate half-esters, methacrylates were also introduced to the glyceride structure via methacrylation of the soybean oil glycerolysis product with methacrylic anhydride. This product, which contains methacrylic acid as by-product, and its blends with styrene also gave rigid materials when cured. The triglyceride based monomers were characterized via conventional spectroscopic techniques. Time resolved FTIR analysis was used to determine the curing kinetics and the final conversions of polymerization of the malinated glyceride-styrene blends. Dynamic Mechanical Analysis (DMA) was used to determine the thermomechanical behavior of these polymers and other mechanical properties were determined via standard mechanical tests. The use of lignin

  1. Permeability characterization of polymer matrix composites by RTM/VARTM

    NASA Astrophysics Data System (ADS)

    Naik, N. K.; Sirisha, M.; Inani, A.

    2014-02-01

    Cost effective manufacturing of high performance polymer matrix composite structures is an important consideration for the growth of its use. Resin transfer moulding (RTM) and vacuum assisted resin transfer moulding (VARTM) are the efficient processes for the cost effective manufacturing. These processes involve transfer of resin from the tank into the reinforcing preform loaded into a closed mould. Resin flow within the preform and reinforcement wetting can be characterized using the permeability properties. Different reinforcement and resin properties and process parameters affecting the permeability are discussed based on state of art literature review covering experimental studies. General theory for the determination of permeability is presented. Based on the literature review, permeability values for different reinforcement architecture, resin and processing conditions are presented. Further, possible sources of error during experimental determination of permeability and issues involved with reproducibility are discussed.

  2. Synthesis And Characterization Of Reduced Size Ferrite Reinforced Polymer Composites

    SciTech Connect

    Borah, Subasit; Bhattacharyya, Nidhi S.

    2008-04-24

    Small sized Co{sub 1-x}Ni{sub x}Fe{sub 2}O{sub 4} ferrite particles are synthesized by chemical route. The precursor materials are annealed at 400, 600 and 800 C. The crystallographic structure and phases of the samples are characterized by X-ray diffraction (XRD). The annealed ferrite samples crystallized into cubic spinel structure. Transmission Electron Microscopy (TEM) micrographs show that the average particle size of the samples are <20 nm. Particulate magneto-polymer composite materials are fabricated by reinforcing low density polyethylene (LDPE) matrix with the ferrite samples. The B-H loop study conducted at 10 kHz on the toroid shaped composite samples shows reduction in magnetic losses with decrease in size of the filler sample. Magnetic losses are detrimental for applications of ferrite at high powers. The reduction in magnetic loss shows a possible application of Co-Ni ferrites at high microwave power levels.

  3. Fabrication and characterization of solid state conducting polymer actuators

    NASA Astrophysics Data System (ADS)

    Xie, Jian; Sansinena, Jose-Maria; Gao, Junbo; Wang, Hsing-Lin

    2004-07-01

    We report here the fabrication and characterization of solid-state conducting polymer actuators. The electrochemical activity of polyaniline (PANI) thin film coated with solid-state polyelectrolyte is very similar to the polyaniline thin film in an aqueous solution. The solid-state actuator is adhered to a lever arm of a force transducer and the force generation is measured in real time. The force generated by the actuator is found to be length dependent. However, the overall torque generated by the actuators with different lengths remains essentially the same. The effect of stimulation signals such as voltage, and current, on the bending angle and displacement is also studied using square wave potential.

  4. Optimization, evaluation, and characterization of molecularly imprinted polymers.

    PubMed

    Spivak, David A

    2005-12-06

    The underlying mechanisms for molecular recognition exhibited by the imprinting effect can be attributed to two processes. The pre-organization of complementary functional groups in the polymer by the template and the formation of a shape-selective cavity that is complementary to the template. However, measurements of binding and selectivity combine all effects contributing to molecular recognition in MIPs into one figure of merit. If the two molecules being compared are not enantiomers, then there are other factors which contribute to differential binding such as size or different partitioning effects due to differences in polarity, hydrophobicity, ionization state or shape and/or conformational effects. The best probe for the imprinting effect is therefore an enantiomeric pair. Therefore, the first section of this article discusses enantioselective optimization of polymerization, the second section will review methods employed for evaluation of MIPs and the last section will cover materials science methods used to characterize the physical properties of MIP materials.

  5. Characterization of molecularly imprinted polymer nanoparticles by photon correlation spectroscopy.

    PubMed

    Malm, Björn; Yoshimatsu, Keiichi; Ye, Lei; Krozer, Anatol

    2014-12-01

    We follow template-binding induced aggregation of nanoparticles enantioselectively imprinted against (S)-propranolol, and the non-imprinted ones, using photon correlation spectroscopy (dynamic light scattering). The method requires no separation steps. We have characterized binding of (R,S)-propranolol to the imprinted polymers and determined the degree of non-specificity by comparing the specific binding with the results obtained using non-imprinted nanoparticles. Using (S)-propranolol as a template for binding to (S)-imprinted nanoparticle, and (R)-propranolol as a non-specific control, we have determined range of concentrations where chiral recognition can be observed. By studying aggregation induced by three analytes related to propranolol, atenolol, betaxolol, and 1-amino-3-(naphthalen-1-yloxy)propan-2-ol, we were able to determine which parts of the template are involved in the specific binding, discuss several details of specific adsorption, and the structure of the imprinted site.

  6. Characterization of Polymer Blends: Optical Microscopy (*Polarized, Interference and Phase Contrast Microscopy*) and Confocal Microscopy

    SciTech Connect

    Ramanathan, Nathan Muruganathan; Darling, Seth B.

    2015-01-01

    Chapter 15 surveys the characterization of macro, micro and meso morphologies of polymer blends by optical microscopy. Confocal Microscopy offers the ability to view the three dimensional morphology of polymer blends, popular in characterization of biological systems. Confocal microscopy uses point illumination and a spatial pinhole to eliminate out-of focus light in samples that are thicker than the focal plane.

  7. Formation and characterization of polymer jets in electrospinning

    NASA Astrophysics Data System (ADS)

    Xu, Han

    The electrospinning jet is defined as a continuous fluid flow ejected from the surface of a fluid when the applied electrical force overcomes the surface tension of the fluid. The electrospinning jet is a micron-scale, often vibrating, tapered, fast developing, electrically charged fluid flow with a high tensile force along the axis. These characteristics create many difficulties in understanding the nature of the jet. The formation and development of the electrospinning jets was introduced using a newly discovered slow developing electrospinning system. The reasons for this system to spin considerably slower and larger in scale than most of the other systems reported were discussed. A fluid mechanical stretching apparatus was designed to apply a uniaxial elongation to the polymer fluid. A rheological model was developed to interpret the experimental data. The elongational relaxation time and the elongational viscosity of polymer solutions were characterized. A novel method was developed to characterize the micron scale jet diameter from the interference color shown on the jet. The relationship between the jet diameter and the interference color on the jet was investigated experimentally and theoretically. The jet diameters were calculated from the interference colors by a comprehensive computer model developed. It was also demonstrated that interference fringes on a cylindrical jet generated by a plane of laser light can be used to characterize the diameter of a micron scale jet. Fluid velocities as a function of positions along the jet axis were characterized by tracing particle movement during electrospinning using high-speed photography. The effects of the electric field on the fluid jet velocity and acceleration were investigated. The strain rate of the electrospinning jets was calculated from the jet diameter, the taper rate and the jet velocity. The strain rate increases when spinning voltage is decreased. The strain rate at different positions along jet

  8. Characterization and preparation of p(U-MMA-An) interpenetrating polymer network damping and absorbing material.

    PubMed

    Liu, Jun; Li, Qingshan; Zhuo, Yuguo; Hong, Wei; Lv, Wenfeng; Xing, Guangzhong

    2014-06-01

    P(U-MMA-ANI) interpenetrating polymer network (IPN) damping and absorbing material is successfully synthesized by PANI particles served as an absorbing agent with the microemulsion polymerization and P(U-MMA) foam IPN network structure for substrate materials with foaming way. P(U-MMA-ANI) IPN is characterized by the compression mechanical performance testing, TG-DSC, and DSC. The results verify that the P(U-MMA) IPN foam damping material has a good compressive strength and compaction cycle property, and the optimum content of PMMA was 40% (mass) with which the SEM graphs do not present the phase separation on the macro level between PMMA and PU, while the phase separation was observed on the micro level. The DTG curve indicates that because of the formation of P(U-MMA) IPN, the decomposition temperature of PMMA and the carbamate in PU increases, while that of the polyol segment in PU has almost no change. P(U-MMA-ANI) IPN foam damping and absorbing material is obtained by PANI particles served as absorbing agent in the form of filler, and PMMA in the form of micro area in substrate material. When the content of PANI was up to 2.0% (mass), the dissipation factor of composites increased, and with the increasing of frequency the dissipation factor increased in a straight line.

  9. Mass Spectrometry Characterization of the Thermal Decomposition/Digestion (TDD) at Cysteine in Peptides and Proteins in the Condensed Phase

    NASA Astrophysics Data System (ADS)

    Basile, Franco; Zhang, Shaofeng; Kandar, Sujit Kumar; Lu, Liang

    2011-11-01

    We report on the characterization by mass spectrometry (MS) of a rapid, reagentless and site-specific cleavage at the N-terminus of the amino acid cysteine (C) in peptides and proteins induced by the thermal decomposition at 220-250 °C for 10 s in solid samples. This thermally induced cleavage at C occurs under the same conditions and simultaneously to our previously reported thermally induced site-specific cleavage at the C-terminus of aspartic acid (D) (Zhang, S.; Basile, F. J. Proteome Res. 2007, 6, (5), 1700-1704). The C cleavage proceeds through cleavage of the nitrogen and α-carbon bond (N-terminus) of cysteine and produces modifications at the cleavage site with an amidation (-1 Da) of the N-terminal thermal decomposition product and a -32 Da mass change of the C-terminal thermal decomposition product, the latter yielding either an alanine or β-alanine residue at the N-terminus site. These modifications were confirmed by off-line thermal decomposition electrospray ionization (ESI)-MS, tandem MS (MS/MS) analyses and accurate mass measurements of standard peptides. Molecular oxygen was found to be required for the thermal decomposition and cleavage at C as it induced an initial cysteine thiol side chain oxidation to sulfinic acid. Similar to the thermally induced D cleavage, missed cleavages at C were also observed. The combined thermally induced digestion process at D and C, termed thermal decomposition/digestion (TDD), was observed on several model proteins tested under ambient conditions and the site-specificity of the method confirmed by MS/MS.

  10. Electrochemical characterization of redox polymer modified electrode developed for monitoring of adenine.

    PubMed

    Kuralay, Filiz; Erdem, Arzum; Abacı, Serdar; Ozyörük, Haluk

    2013-05-01

    Electrochemical characterization of redox polymer for monitoring of adenine was described in this study using poly(vinylferrocenium) (PVF(+)) modified platinum (Pt) electrode. Scanning electron microscope (SEM) was used for the surface characterization. The electrochemical behaviors of polymer modified and adenine immobilized polymer modified electrodes were investigated by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In order to obtain more sensitive and improved electrochemical signals, analytical parameters such as the effects of polymeric film thickness, immobilization time of adenine, pH and adenine concentration were examined on the response of the polymer modified electrode. Alternating current (AC) impedance spectroscopy was used for the characterization of polymer modified and adenine immobilized polymer modified electrodes. The effect of possible interferents on the response of the electrode was examined.

  11. Characterization and optimization of polymer electrolyte fuel cell electrodes

    NASA Astrophysics Data System (ADS)

    Boyer, Christopher Carter

    Experimental characterization and modeling were combined to find a procedure for optimizing the design of polymer electrolyte membrane fuel cell (PEMFC) electrodes. The mass transfer and kinetic properties of the active layer used in electrodes fabricated at the Center for Electrochemical Systems and Hydrogen Research (CESHR) were characterized as a function of electrolyte polymer content NafionRTM, DuPont, Fayetteville, NC) and catalyst loading for different types of platinum catalysts (E-Tek, Natick, MA). Expressions from limiting cases of the fuel cell model showed the combination of electrode materials for maximum current density at maximum catalyst utilization. Models describing the fuel cell behavior were selected and used to explain how different operating pressures affect the system power density and efficiency. An "inert layer" method was developed to determine the effective proton conductivity of the active layer. A "buffer layer" method was developed to determine the oxygen diffusivity in the gas pores. A review of the literature and experiments at CESHR was used to determine the oxygen reduction activity of the active layer. Finally, a fitting method was developed to measure the agglomerate diffusivity from cell tests. A PEMFC model demonstrated that operating the fuel cell pressurized can improve the power density at high currents because of oxygen mass transport. limitations in the substrate. However. as better electrode designs improve oxygen mass transfer, pressurized operation will lose this advantage. In addition, the model confirmed that oxygen enrichment systems require too much energy to separate oxygen from air to improve the net performance of a fuel cell. From limiting approximations of the solutions of the differential material balances in the fuel cell model, a simple set of analytical expressions were derived that predict the optimum active layer thickness and maximum current density based on the materials of construction and operating

  12. Materials development and electrochemical characterization of polymer electrolyte fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Xin

    In this thesis, the materials development and mechanism characterizations of polymer electrolyte fuel cells (PEFCs) are addressed. This work starts with a new preparation technique for a modified electrode structure containing two carbon support materials. The resulted catalyzed electrode, which exhibits good materials properties, demonstrates an improved kinetics in the oxygen reduction reaction (ORR). A new electrocatalyst synthesis procedure utilizing an amphiphilic surfactant to stabilize the nanophase catalyst particles is proposed to fabricate the Pt and Pt-Ru electrocatalysts supported on carbon powders. Physicochemical and electrochemical characterizations of this electrocatalyst show that the nanmeter-scale, well-dispersed catalyst with a high catalytic activity can be obtained. In addition to developing the electrocatalytic materials, an electrochemical impedance based study, aiming to achieve a better understanding of the H 2/CO and methanol oxidation mechanism, is carried out. Unlike the equivalent circuit fitting model frequently used in the fuel cell community, a mathematical simulation tool, utilizing the impedance theory and the reaction kinetics, is developed. This model not only successfully predicts the effects of applied potentials to the impedance but also captures most of the impedance characteristics found in the experiments. In particular, the occurrence of the "pseudo inductive" behavior observed both in the experiments and simulations can be used as an effective criterion for the onset of surface CO oxidation. It is believed that the simulation strategy employed in this study can be utilized to assist the materials design of electrocatalysts with improved CO tolerance and high electrocatalytic activity.

  13. Micromechanical characterization tools for highly-filled polymers

    SciTech Connect

    Groves, S; DeTeresa, S; Cunningham, B; Ciarlo, D; Allen, D; Clayton, K; Yoon, C

    2000-02-16

    We are attempting to characterize and model the micromechanical response of highly-filled polymers. In this class of materials, the continuous plastic binder used to bond the highly-filled material dominates the observed viscoelastic response. As a result, realistic lifetime analysis of these materials will require a thorough understanding of the contribution of the plastic binder. Laboratory applications of these materials include plastic bonded explosives, propellants, a variety of specialized filled organic materials for stockpile systems, and highly filled epoxy dielectric materials for the National Ignition Facility. We have explored numerous techniques to characterize the local microstructure of plastic bonded explosives. However, insufficient funding was obtained to bring these technologies to maturity, nevertheless our present tool set is significantly better than 2 years ago. We have also made some progress in developing an appropriate micromechanical constitutive modeling framework, based on a finite element method incorporating a cohesive zone model to represent the binder contribution within a Voronoi tesselation mesh structure for the PBX grains. A second modeling approach was used to incorporate analytical micromechanics (generalized self-consistent schemes). However, preliminary theoretical analysis strongly suggested that this approach would be invalid for such extremely high-filled systems like PBX.

  14. Dendronized Polymers: Synthesis, Characterization, Assembly at Interfaces, and Manipulation.

    PubMed

    Schlüter; Rabe

    2000-03-01

    Dendrimers are presently one of the most intensely studied classes of compounds because of their unusual structure. They can be described as a jungle of entangled branches traversed by winding trails which lead to sweet fruits and bright blossoms. On these trails one can reach the thicket's interior as well as find a way out. Expressed less lyrically, this thicket stands for regularly branched, densely packed structures, and the trails represent voids and channels not filled by bent back branches but by solvent. The fruit and blossoms are photochemically, electrochemically, or synthetically addressable units, catalytically active sites, etc., and the back and forth on the trails stands for transport processes. In a mathematical sense dendrimers are enveloped by an interface, which defines what is either in or out. This interface is shaped like a sphere if the trails are filled to bursting. Otherwise dendrimers are more flattened like amoeba, especially if in contact with a surface. The high density of the functional groups, the expansion of these compounds to a range of several nanometers, the existence of usable "surface" and transport possibilities in and with them have made dendrimers interesting candidates for many applications. This review describes how dendrimer construction and polymer synthesis were combined and used to move from fully or flattened spherical shapes to cylindrical ones. The shape-inducing influence of dendritic substituents can be driven to create nanoobjects with a cylindrical shape, which not only considerably widens the range of applications for the dendrimer class but also opens up new perspectives for supramolecular and polymer chemistry. Because of the sheer size of the described objects and complexity of shape-related properties, research in this area must necessarily be interdisciplinary. This article tries to mirror this by giving special attention not only to synthesis but also the characterization and behavior of these compounds

  15. Chitosan based oligoamine polymers: synthesis, characterization, and gene delivery.

    PubMed

    Lu, Bo; Wang, Chang-Fang; Wu, De-Qun; Li, Cao; Zhang, Xian-Zheng; Zhuo, Ren-Xi

    2009-07-01

    A series of chitosan-based oligoamine polymers was synthesized from N-maleated chitosan (NMC) via Michael addition with diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA) and linear polyethylenimine (M(n) 423), respectively. The resulted polymers exhibited well binding ability to condense plasmid DNA to form complexes with size ranging from 200 to 600 nm when the polymer/DNA weight ratio was above 7. The polymer/DNA complexes observed by scanning electron microscopy (SEM) exhibited a compact and spherical morphology. The cytotoxicity assay showed that the synthesized polymers were less toxic than that of PEI(25 K). The gene transfection effect of resulted polymers was evaluated in 293T and HeLa cells, and the results showed that the gene transfection efficiency of these polymers was better than that of chitosan. Moreover, the transfection efficiency was dependent on the length of the oligoamine side chains and the molecular weight of the chitosan derivatives.

  16. Automated metric characterization of urban structure using building decomposition from very high resolution imagery

    NASA Astrophysics Data System (ADS)

    Heinzel, Johannes; Kemper, Thomas

    2015-03-01

    Classification approaches for urban areas are mostly of qualitative and semantic nature. They produce interpreted classes similar to those from land cover and land use classifications. As a complement to those classes, quantitative measures directly derived from the image could lead to a metric characterization of the urban area. While these metrics lack of qualitative interpretation they are able to provide objective measure of the urban structures. Such quantitative measures are especially important in rapidly growing cities since, beside of the growth in area, they can provide structural information for specific areas and detect changes. Rustenburg, which serves as test area for the present study, is amongst the fastest growing cities in South Africa. It reveals a heterogeneous face of housing and building structures reflecting social and/or economic differences often linked to the spatial distribution of industrial and local mining sites. Up to date coverage with aerial photographs is provided by aerial surveys in regular intervals. Also recent satellite systems provide imagery with suitable resolution. Using such set of very high resolution images a fully automated algorithm has been developed which outputs metric classes by systematically combining important measures of building structure. The measurements are gained by decomposition of buildings directly from the imagery and by using methods from mathematical morphology. The decomposed building objects serve as basis for the computation of grid statistics. Finally a systematic combination of the single features leads to combined metrical classes. For the dominant urban structures verification results indicate an overall accuracy of at least 80% on the single feature level and 70% for the combined classes.

  17. Isotropic photo-decomposition of spherical organic polymers on rutile TiO2(110) surfaces

    NASA Astrophysics Data System (ADS)

    Ishida, Nobuyuki; Iwasaki, Tamaki; Fujita, Daisuke

    2011-04-01

    We observed the photo-decomposition process of polystyrene latex (PSL) spheres on a rutile TiO2(110) single crystal surface by using atomic force microscopy. During the decomposition process, both the height and width of the PSL spheres linearly decreased with the irradiation time in a similar way from the beginning, suggesting that the PSL spheres are isotropically decomposed. This indicates that the interface between the PSL spheres and the TiO2 surface is not a dominant reaction site, as expected from normal photocatalytic reactions.

  18. Synthesis Characterization and Decomposition Studies of tris[N-N-dibenzyidithocarbaso)Indium (III) Chemical Spray Deposition of Polycrystalline CuInS2 on Copper Films

    NASA Technical Reports Server (NTRS)

    Hehemann, David G.; Lau, J. Eva; Harris, Jerry D.; Hoops, Michael D.; Duffy, Norman V.

    2005-01-01

    This paper presents the results of the synthesis characterization and decomposition studies of tris[N-N-dibenzyidithocarbaso)Indium (III) with chemical spray deposition of polycrystalline CuInS2 on Copper Films.

  19. Photothermal and morphological characterization of PLA/PCL polymer blends

    NASA Astrophysics Data System (ADS)

    Correa-Pacheco, Z. N.; Jiménez-Pérez, J. L.; Sabino, M. A.; Cruz-Orea, A.; Loaiza, M.

    2015-09-01

    Nowadays, some synthetic polymers have been replaced by biodegradable polymers in order to avoid environmental contamination. Among these biodegradables polymers, aliphatic polyesters such as polylactic acid (PLA) and polycaprolactone (PCL) have been widely used. In the present study, solvent-casting films of PLA, PCL and polymer blends with and without compatibilizer (PLA grafted with maleic anhydride) were prepared. The thermal diffusivity ( α) of each sample was obtained by using the open photoacoustic cell technique. Morphology and thermal properties were determined by using scanning electron microscopy, transmission electron microscopy and differential scanning calorimetry (DSC), respectively. The blends showed lower thermal diffusivity compared to pure polymers. However, when the compatibilizer was used, the highest value of thermal diffusivity was obtained. Also, cold crystallization with the highest value of enthalpy of fusion was observed for the compatibilized sample, which was revealed by DSC. To our knowledge, this is the first time that the thermal diffusivity of these biodegradable polymer blends is reported.

  20. Synthesis and Characterization of Polymers for Fuel Cells Application

    NASA Technical Reports Server (NTRS)

    Tytko, Stephen F.

    2003-01-01

    The goal of this summer research is to prepare Polymer Exchange Membranes (PEM s) for fuel cell application. Several high temperature polymers such as polybenzimidazoles and polyether ketones were known to possess good high temperature stability and had been investigated by post-sulfonation to yield sulfonated polymers. The research project will involve two approaches: 1. Synthesis of polybenzimidazoles and then react with alkyl sultonse to attach an aliphatic sulfonic groups. 2. Synthesis of monomers containing sulfonic acid units either on a aromatic ring or on an aliphatic chain and then polymerize the monomers to form high molecular weight sulfonate polymers.

  1. Submicron magnetic core conducting polypyrrole polymer shell: Preparation and characterization.

    PubMed

    Tenório-Neto, Ernandes Taveira; Baraket, Abdoullatif; Kabbaj, Dounia; Zine, Nadia; Errachid, Abdelhamid; Fessi, Hatem; Kunita, Marcos Hiroiuqui; Elaissari, Abdelhamid

    2016-04-01

    Magnetic particles are of great interest in various biomedical applications, such as, sample preparation, in vitro biomedical diagnosis, and both in vivo diagnosis and therapy. For in vitro applications and especially in labs-on-a-chip, microfluidics, microsystems, or biosensors, the needed magnetic dispersion should answer various criteria, for instance, submicron size in order to avoid a rapid sedimentation rate, fast separations under an applied magnetic field, and appreciable colloidal stability (stable dispersion under shearing process). Then, the aim of this work was to prepare highly magnetic particles with a magnetic core and conducting polymer shell particles in order to be used not only as a carrier, but also for the in vitro detection step. The prepared magnetic seed dispersions were functionalized using pyrrole and pyrrole-2-carboxylic acid. The obtained core-shell particles were characterized in terms of particle size, size distribution, magnetization properties, FTIR analysis, surface morphology, chemical composition, and finally, the conducting property of those particles were evaluated by cyclic voltammetry. The obtained functional submicron highly magnetic particles are found to be conducting material bearing function carboxylic group on the surface. These promising conducting magnetic particles can be used for both transport and lab-on-a-chip detection.

  2. Carboxylated magnetic polymer nanolatexes: Preparation, characterization and biomedical applications

    NASA Astrophysics Data System (ADS)

    Zheng, Weiming; Gao, Feng; Gu, Hongchen

    2005-05-01

    Carboxylated magnetic polymer nanolatexes were prepared by miniemulsion polymerization using 4,4'-azobis(4-cyanopentanoic acid) (ACPA) as initiator, which provided carboxyl end groups on the latex surface directly. The colloidal stability and the magnetic properties showed that these resulting carboxylated magnetic polymer nanolatexes were applicable in biomedical separation, which was performed by covalent coupling of activated antibody.

  3. Characterization and decomposition of residue from winter and spring canola cultivars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The residue characteristics and decomposition of spring and winter canola (Brassica napus L.) cultivars currently grown in the Pacific Northwest (PNW) was investigated. Above- and below-ground residue was collected post-harvest in 2011 and 2012 from Univ. of Idaho Canola Winter Variety Trials at Od...

  4. The rheology, degradation, processing, and characterization of renewable resource polymers

    NASA Astrophysics Data System (ADS)

    Conrad, Jason David

    Renewable resource polymers have become an increasingly popular alternative to conventional fossil fuel based polymers over the past couple decades. The push by the government as well as both industrial and consumer markets to go "green" has provided the drive for companies to research and develop new materials that are more environmentally friendly and which are derived from renewable materials. Two polymers that are currently being produced commercially are poly-lactic acid (PLA) and polyhydroxyalkanoate (PHA) copolymers, both of which can be derived from renewable feedstocks and have shown to exhibit similar properties to conventional materials such as polypropylene, polyethylene, polystyrene, and PET. PLA and PHA are being used in many applications including food packaging, disposable cups, grocery bags, and biomedical applications. In this work, we report on the rheological properties of blends of PLA and PHA copolymers. The specific materials used in the study include Natureworks RTM 7000D grade PLA and PHA copolymers of poly(3-hydroxybutyrate-co-3-hydroxyvalerate). Blends ranging from 10 to 50 percent PHA by weight are also examined. Shear and extensional experiments are performed to characterize the flow behavior of the materials in different flow fields. Transient experiments are performed to study the shear rheology over time in order to determine how the viscoelastic properties change under typical processing conditions and understand the thermal degradation behavior of the materials. For the blends, it is determined that increasing the PHA concentration in the blend results in a decrease in viscosity and increase in degradation. Models are fit to the viscosity of the blends using the pure material viscosities in order to be able to predict the behavior at a given blend composition. We also investigate the processability of these materials into films and examine the resultant properties of the cast films. The mechanical and thermal properties of the

  5. Synthesis and Characterization of Ca, Mg, La- PMMA Polymer Composites for Phosphate Removal

    EPA Science Inventory

    In this study calcium, magnesium and lanthanum- PMMA polymer composites were synthesized, characterized and investigated for phosphate removal from wastewater using rapid small scale column tests. Theoretical and experimental capacity of the media was determined and unused and sp...

  6. Characterization of High Temperature Polymer Thin Films for Power Conditioning Capacitors

    DTIC Science & Technology

    2009-07-01

    Characterization of High Temperature Polymer Thin Films for Power Conditioning Capacitors by Janet Ho and Richard Jow ARL-TR-4880 July...TR-4880 July 2009 Characterization of High Temperature Polymer Thin Films for Power Conditioning Capacitors Janet Ho and Richard Jow...Films for Power Conditioning Capacitors 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5e. TASK NUMBER 6. AUTHOR(S) Janet Ho and Richard Jow 5f

  7. Synthesis, Decomposition and Characterization of Fe and Ni Sulfides and Fe and CO Nanoparticles for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Cowen, Jonathan E.; Hepp, Aloysius F.; Duffy, Norman V.; Jose, Melanie J.; Choi, D. B.; Brothers, Scott M.; Baird, Michael F.; Tomsik, Thomas M.; Duraj, Stan A.; Williams, Jennifer N.; Kulis, Michael J.; Gaier, James R.

    2009-01-01

    We describe several related studies where simple iron, nickel, and cobalt complexes were prepared, decomposed, and characterized for aeronautics (Fischer-Tropsch catalysts) and space (high-fidelity lunar regolith simulant additives) applications. We describe the synthesis and decomposition of several new nickel dithiocarbamate complexes. Decomposition resulted in a somewhat complicated product mix with NiS predominating. The thermogravimetric analysis of fifteen tris(diorganodithiocarbamato)iron(III) has been investigated. Each undergoes substantial mass loss upon pyrolysis in a nitrogen atmosphere between 195 and 370 C, with major mass losses occurring between 279 and 324 C. Steric repulsion between organic substituents generally decreased the decomposition temperature. The product of the pyrolysis was not well defined, but usually consistent with being either FeS or Fe2S3 or a combination of these. Iron nanoparticles were grown in a silica matrix with a long-term goal of introducing native iron into a commercial lunar dust simulant in order to more closely simulate actual lunar regolith. This was also one goal of the iron and nickel sulfide studies. Finally, cobalt nanoparticle synthesis is being studied in order to develop alternatives to crude processing of cobalt salts with ceramic supports for Fischer-Tropsch synthesis.

  8. Synthesis and Characterization of Molecular Imprinting Polymer Microspheres of Piperine: Extraction of Piperine from Spiked Urine.

    PubMed

    Roland, Rachel Marcella; Bhawani, Showkat Ahmad

    2016-01-01

    Molecularly imprinted polymer (MIP) microspheres for Piperine were synthesized by precipitation polymerization with a noncovalent approach. In this research Piperine was used as a template, acrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, and 2,2'-azobisisobutyronitrile (AIBN) as an initiator and acetonitrile as a solvent. The imprinted and nonimprinted polymer particles were characterized by using Fourier transform infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). The synthesized polymer particles were further evaluated for their rebinding efficiency by batch binding assay. The highly selected imprinted polymer for Piperine was MIP 3 with a composition (molar ratio) of 0.5 : 3 : 8, template : monomer : cross-linker, respectively. The MIP 3 exhibits highest binding capacity (84.94%) as compared to other imprinted and nonimprinted polymers. The extraction efficiency of highly selected imprinted polymer of Piperine from spiked urine was above 80%.

  9. Synthesis and Characterization of Molecular Imprinting Polymer Microspheres of Piperine: Extraction of Piperine from Spiked Urine

    PubMed Central

    Roland, Rachel Marcella

    2016-01-01

    Molecularly imprinted polymer (MIP) microspheres for Piperine were synthesized by precipitation polymerization with a noncovalent approach. In this research Piperine was used as a template, acrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, and 2,2′-azobisisobutyronitrile (AIBN) as an initiator and acetonitrile as a solvent. The imprinted and nonimprinted polymer particles were characterized by using Fourier transform infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM). The synthesized polymer particles were further evaluated for their rebinding efficiency by batch binding assay. The highly selected imprinted polymer for Piperine was MIP 3 with a composition (molar ratio) of 0.5 : 3 : 8, template : monomer : cross-linker, respectively. The MIP 3 exhibits highest binding capacity (84.94%) as compared to other imprinted and nonimprinted polymers. The extraction efficiency of highly selected imprinted polymer of Piperine from spiked urine was above 80%. PMID:28018704

  10. Synthesis, Characterization and Biological Studies of New Linear Thermally Stable Schiff Base Polymers with Flexible Spacers.

    PubMed

    Qureshi, Farah; Khuhawar, Muhammad Yar; Jahangir, Taj Muhammad; Channar, Abdul Hamid

    2016-01-01

    Five new linear Schiff base polymers having azomethine structures, ether linkages and extended aliphatic chain lengths with flexible spacers were synthesized by polycondensation of dialdehyde (monomer) with aliphatic and aromatic diamines. The formation yields of monomer and polymers were obtained within 75-92%. The polymers with flexible spacers of n-hexane were somewhat soluble in acetone, chloroform, THF, DMF and DMSO on heating. The monomer and polymers were characterized by melting point, elemental microanalysis, FT-IR, (1)HNMR, UV-Vis spectroscopy, thermogravimetry (TG), differential thermal analysis (DTA), fluorescence emission, scanning electron microscopy (SEM) and viscosities and thermodynamic parameters measurements of their dilute solutions. The studies supported formation of the monomer and polymers and on the basis of these studies their structures have been assigned. The synthesized polymers were tested for their antibacterial and antifungal activities.

  11. Characterization of tissue-simulating polymers for photoacoustic vascular imaging

    NASA Astrophysics Data System (ADS)

    Vogt, William C.; Jia, Congxian; Garra, Brian S.; Pfefer, T. Joshua

    2014-05-01

    Photoacoustic tomography (PAT) is a maturing imaging technique which combines optical excitation and acoustic detection to enable deep tissue sensing for biomedical applications. Optical absorption provides biochemical specificity and high optical contrast while ultrasonic detection provides high spatial resolution and penetration depth. These characteristics make PAT highly suitable as an approach for vascular imaging. However, standard testing methods are needed in order to characterize and compare the performance of these systems. Tissue-mimicking phantoms are commonly used as standard test samples for imaging system development and evaluation due to their repeatable fabrication and tunable properties. The multi-domain mechanism behind PAT necessitates development of phantoms that accurately mimic both acoustic and optical properties of tissues. While a wide variety of materials have been used in the literature, from gelatin and agar hydrogels to silicone, published data indicates that poly(vinyl chloride) plastisol (PVCP) is a promising candidate material for simulating tissue optical and acoustic properties while also providing superior longevity and stability. Critical acoustic properties of PVCP phantoms, including sound velocity and attenuation, were measured using acoustic transmission measurements at multiple frequencies relevant to typical PAT systems. Optical absorption and scattering coefficients of PVCP gels with and without biologically relevant absorbers and scatterers were measured over wavelengths from 500 to 1100 nm. A custom PAT system was developed to assess image contrast in PVCP phantoms containing fluid channels filled with absorbing dye. PVCP demonstrates strong potential as the basis of high-fidelity polymer phantoms for developing and evaluating PAT systems for vascular imaging applications.

  12. Electrical characterization of proton conducting polymer electrolyte based on bio polymer with acid dopant

    NASA Astrophysics Data System (ADS)

    Kalaiselvimary, J.; Pradeepa, P.; Sowmya, G.; Edwinraj, S.; Prabhu, M. Ramesh

    2016-05-01

    This study describes the biodegradable acid doped films composed of chitosan and Perchloric acid with different ratios (2.5 wt %, 5 wt %, 7.5 wt %, 10 wt %) was prepared by the solution casting technique. The temperature dependence of the proton conductivity of complex electrolytes obeys the Arrhenius relationship. Proton conductivity of the prepared polymer electrolyte of the bio polymer with acid doped was measured to be approximately 5.90 × 10-4 Scm-1. The dielectric data were analyzed using Complex impedance Z*, Dielectric loss ɛ', Tangent loss for prepared polymer electrolyte membrane with the highest conductivity samples at various temperature.

  13. Thermochemical characterization of some thermally stable thermoplastic and thermoset polymers

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.; Gilwee, W. J., Jr.; Parker, J. A.

    1979-01-01

    The thermochemical and flammability properties of some thermally stable polymers considered for use in aircraft interiors are described. The properties studied include: (1) thermomechanical properties such as glass transition and melt temperature; (2) dynamic thermogravimetric analysis in anaerobic environment; (3) flammability properties such as oxygen index, flame spread, and smoke evolution; and (4) selected physical properties. The thermoplastic polymers evaluated include polyphenylene sulfide, polyaryl sulfone, 9,9-bis(4-hydroxyphenyl)-fluorene polycarbonate-poly(dimethylsiloxane) and polyether sulfone. The thermoset polymers evaluated include epoxy, bismaleimide, a modified phenolic, and polyaromatic melamine resin. These resins were primarily used in the fabrication of glass-reinforced prepregs for the construction of experimental panels. Test results and relative rankings of some of the flammability parameters are presented, and the relationship of the molecular structure, char yield, and flammability properties of these polymers are discussed.

  14. Preparation and characterization of barium hexaferrite powders produced by decomposition of organometallic complexes

    SciTech Connect

    Chandrasekhar, R.; Charles, S.W.; O'Grady, K. ); Moerup, S.; van Wonterghem, J. )

    1987-01-01

    Barium hexaferrite (BaFe{sub 12}O{sub 19}) particles have been prepared by the decomposition of an organometallic salt. The properties of the ferrite particles have been investigated by x-ray diffractometry, Moessbauer spectroscopy, scanning electron microscopy, and magnetic measurements. The size of the particles produced lie between 0.1 and 0.5 {mu}m. To form the hexaferrite the decomposition product must be heated to > 620{degree}C. Typical values of the saturation magnetization, coercivity, and remanence ratio of the hexaferrite particles are 333 kA{center dot}m{sup {minus}1} (63 emu/g{sup {minus}1}), 320 kA{center dot}m{sup {minus}1} (4 kOe), and 0.49, respectively.

  15. Processing and Characterization of Shape Memory Polymer Nanocomposites (Preprint)

    DTIC Science & Technology

    2006-02-01

    Group on Polymer Nanocomposites- PNC- Tech, http://www.imi.cnrc-nrc.gc.ca/ english /Default.htm. 2. Zhu, J ., et al ., “Reinforcing Epoxy Polymer Composites...through Covalent Integration of Functionalized Nanotubes”, Advanced Functional Materials, No. 7, 2004, pp.643-648. 3. Zeng, J ., et al , “Processing...Barrera, V., “A Study on Nanofiber-Reinforced Thermoplastic Composites (II): Investigation of the mixing Rheology and Conduction Properties

  16. Design, Synthesis and Characterization of Novel Nonlinear Optical Polymers

    DTIC Science & Technology

    1994-05-31

    spin coating or casting from solutions, the polymer chains self organize in an acentric stable polar organization without recourse to poling. The...heated at 150 ’C for 1 h before spin - coating . * Corona poling technique was used to obtain the second-order NLO property in the polymer films. Poling...assemble in an acentric stable polar organization upon spin coating . Spontaneous alignment of the urethane moiety aided by the intramolecular hydrogen

  17. Studies of the Breakdown Mechanism of Polymers. VII. The Thermal Decomposition of a Polyhydrazide and of Polyoxadiazoles

    DTIC Science & Technology

    monoxide, and carbon dioxide. The major part converts to the corresponding polyoxadiazole. Poly- 1,3-and -1,4-phenylene -2,5(1,3,4- oxadiazole ...1,3-polymer and forms less gaseous products and more condensate. The oxadiazole ring degrades before the benzene ring. Initial competing reactions seem

  18. Characterization and optimization of polymer-ceramic pressure-sensitive paint by controlling polymer content.

    PubMed

    Sakaue, Hirotaka; Kakisako, Takuma; Ishikawa, Hitoshi

    2011-01-01

    A pressure-sensitive paint (PSP) with fast response characteristics that can be sprayed on a test article is studied. This PSP consists of a polymer for spraying and a porous particle for providing the fast response. We controlled the polymer content (%) from 10 to 90% to study its effects on PSP characteristics: the signal level, pressure sensitivity, temperature dependency, and time response. The signal level and temperature dependency shows a peak in the polymer content around 50 to 70%. The pressure sensitivity was fairly constant in the range between 0.8 and 0.9 %/kPa. The time response is improved by lowering the polymer content. The variation of the time response is shown to be on the order of milliseconds to ten seconds. A weight coefficient is introduced to optimize the resultant PSPs. By setting the weight coefficient, we can optimize the PSP for sensing purposes.

  19. Target characterization using decomposition of the time-reversal operator: electromagnetic scattering from small ellipsoids

    SciTech Connect

    Chambers, D H; Berryman, J G

    2006-05-18

    Decomposition of the time-reversal operator for an array, or equivalently the singular value decomposition of the multistatic response matrix, has been used to improve imaging and localization of targets in complicated media. Typically, each singular value is associated with one scatterer even though it has been shown in several cases that a single scatterer can generate several singular values. In earlier papers Chambers and Berryman [1, 2] showed that a small spherical scatterer can generate up to six singular values depending on the array geometry and sphere composition. It was shown that the existence and characteristics of multiple singular values for each scatterer can, in principle, be used to determine certain properties of the scatterers, e.g. conducting or non-conducting material. In this paper, we extend this analysis to non-spherical targets and show how orientation information about the target may be obtained from the spectrum of singular values. The general properties of the decomposition for small non-spherical dielectric (and possibly conductive) targets in an electromagnetic field are derived and detailed results are obtained for the specific cases of non-magnetic and perfectly conducting needles and disks. It is shown that scatterer orientation can be estimated by tracking the singular values of a linear array as it is rotated around its midpoint.

  20. A thermodynamic theory for characterizing thermo-mechanical response of polymers during crystallization

    SciTech Connect

    Negahban, M.

    1995-12-31

    A thermodynamic theory will be presented to capture the thermo-mechanical characteristics associated with crystallization of polymers. The basic characteristics associated with crystallization consists of (a) crystallization in polymers is considered a gradual transition from an amorphous polymer to a semi-crystalline polymer, (b) there is a volume reduction associated with crystallization as the material moves to the denser morphology of the crystal structure, (c) there is a substantial stiffening of the polymer, (d) there is stress relaxation associated with crystallization for polymers under a constant stretch, (e) there is creep associated with crystallization in polymers under a fixed load. These and other characteristics are modeled in a multi-dimensional thermodynamic theory. As a first example, the simplest possible constitutive assumptions are studied in relation to characterizing the behavior of natural rubber. Natural rubber is selected due to the abundance of information on its thermo-mechanical behavior. This work is an extension to non-isothermal thermodynamic processes of previous work on characterizing the mechanical effects of polymer crystallization under isothermal conditions.

  1. Characterization of ionic, dipolar and molecular mobility in polymer systems

    NASA Astrophysics Data System (ADS)

    Guo, Zhenrong

    Changes in the ionic and dipolar molecular mobility in a polymer system are the basis for the changes in the dielectric mechanical properties of polymer materials. Frequency Dependent Dielectric Measurements (FDEMS) and Ion Time-of-Flight (ITOF) are two important techniques to investigate ionic and dipolar molecular mobility in polymer systems. The results can be related to the macro- and molecular dielectric, electrical and dynamic properties of polymeric materials. The combination of these two methods provides a full view of electric, dielectric and dynamic behavior for the systems as they undergo chemical and/or physical changes during polymerization crystallization, vitrification, and/or phase separation. The research on microscopic mass mobility in polymer systems was done on three aspects: (1) ion mobility in an epoxy-amine reaction system; (2) dipolar mobility and relaxation during dimethacrylate resin cure and (3) dye molecule migration and diffusion in polymer films. In the ion mobility study, we separately monitor the changes in the ion mobility and the number of charge carriers during the epoxy-amine polymerization with FDEMS and ITOF measurements. The isolation of the number of carriers and their mobility allows significant improvement in monitoring changes in the state and structure of a material as it cures. For the dipolar mobility and relaxation study, FDEMS measurements were used to detect structural evolution and spatial heterogeneity formation during the polymerization process of dimethacrylate resins. The dielectric spectra, glass transition (Tg) profiles and dynamic mechanical measurements were used to investigate the existence of two cooperative regions of sufficient size to create two alpha-relaxation processes representing oligomer rich and polymer microgel regions during the polymerization. For the dye migration research, we tried to develop a visually color changing paper (VCP) due to dye molecule migration in polymer films. The mobility

  2. Synthesis, Characterization, and Application of Metal-Chelating Polymers for Mass Cytometric Bioassays

    NASA Astrophysics Data System (ADS)

    Majonis, Daniel

    This thesis describes the synthesis, characterization, and application of metal-chelating polymers for mass-cytometric bioassays. Mass cytometry is a cell characterization technique in which cells are injected individually into an ICP-MS detector. Signal is provided by staining cell-surface or intracellular antigens with metal-labeled antibodies (Abs). These Abs are labeled through the covalent attachment of metal-chelating polymers which carry multiple copies of a lanthanide isotope. In this work, my first goal was to develop a facile, straightforward synthesis of a new generation of metal-chelating polymers. The synthesis began with reversible addition-fragmentation chain transfer polymerization, and was followed by numerous post-polymerization pendant group transformations to introduce DTPA lanthanide chelators to every repeat unit, and a maleimide at the end of the chain. The second goal was to apply these metal-chelating polymers in bioassay experiments. The DTPA groups were loaded with lanthanide ions, and the maleimide group was used to covalently attach the polymer to an Ab. This goat anti-mouse conjugate was found to carry an average of 2.4 +/- 0.3 polymer chains. Then, primary Ab conjugates were prepared and used in an 11-plex mass cytometry assay in the characterization of umbilical cord blood cells. The third goal was to expand the multiplexity of the assay. In current technology, the number of Abs that can be monitored simultaneously is limited to the 31 commercially available, stable lanthanide isotopes. Thus, I had an interest in preparing metal-chelating polymers that could carry other metals in the 100-220 amu range. I synthesized polymers with four different polyaminocarboxylate ligands, and investigated the loading of palladium and platinum ions into these polymers. Polymer-Ab conjugates prepared with palladium- and platinum-loaded polymers gave curious results, in that only dead cells were recognized. The fourth goal was to create dual

  3. The use of scanning probe microscopy to characterize polymer blends

    SciTech Connect

    Joseph, T.; Yao, L.; Beatty, C.L.

    1996-12-31

    The use of scanning probe microscopy for the examination of atomic scale phenomena in polymers has been well documented, but the use of scanning probe microscopy to examine submicron scale structures has not been well documented. The purpose of this project was to examine the structure of polymer blends on a submicron scale. Two different systems were studied; a blend of recycled thermoplastics and a blend of ground rubber tire particles in a polystyrene matrix. Topographical images, z modulation plots, internal sensor measurements, and lateral force microscopy images were obtained for both systems. The plots were compared to the structures that we were expected to obtain. A second method of mathematical analysis, fractal dimension measurement, was also performed on the topographical images. Fractal dimension measurement has been correlated to fracture toughness in homopolymers, but the correlation has not been established for polymer blends. Comparison of both methods will be shown.

  4. Characterizing Feedback Control Mechanisms in Nonlinear Microbial Models of Soil Organic Matter Decomposition by Stability Analysis

    NASA Astrophysics Data System (ADS)

    Georgiou, K.; Tang, J.; Riley, W. J.; Torn, M. S.

    2014-12-01

    Soil organic matter (SOM) decomposition is regulated by biotic and abiotic processes. Feedback interactions between such processes may act to dampen oscillatory responses to perturbations from equilibrium. Indeed, although biological oscillations have been observed in small-scale laboratory incubations, the overlying behavior at the plot-scale exhibits a relatively stable response to disturbances in input rates and temperature. Recent studies have demonstrated the ability of microbial models to capture nonlinear feedbacks in SOM decomposition that linear Century-type models are unable to reproduce, such as soil priming in response to increased carbon input. However, these microbial models often exhibit strong oscillatory behavior that is deemed unrealistic. The inherently nonlinear dynamics of SOM decomposition have important implications for global climate-carbon and carbon-concentration feedbacks. It is therefore imperative to represent these dynamics in Earth System Models (ESMs) by introducing sub-models that accurately represent microbial and abiotic processes. In the present study we explore, both analytically and numerically, four microbe-enabled model structures of varying levels of complexity. The most complex model combines microbial physiology, a non-linear mineral sorption isotherm, and enzyme dynamics. Based on detailed stability analysis of the nonlinear dynamics, we calculate the system modes as functions of model parameters. This dependence provides insight into the source of state oscillations. We find that feedback mechanisms that emerge from careful representation of enzyme and mineral interactions, with parameter values in a prescribed range, are critical for both maintaining system stability and capturing realistic responses to disturbances. Corroborating and expanding upon the results of recent studies, we explain the emergence of oscillatory responses and discuss the appropriate microbe-enabled model structure for inclusion in ESMs.

  5. Characterization of molecularly imprinted polymers using a new polar solvent titration method.

    PubMed

    Song, Di; Zhang, Yagang; Geer, Michael F; Shimizu, Ken D

    2014-07-01

    A new method of characterizing molecularly imprinted polymers (MIPs) was developed and tested, which provides a more accurate means of identifying and measuring the molecular imprinting effect. In the new polar solvent titration method, a series of imprinted and non-imprinted polymers were prepared in solutions containing increasing concentrations of a polar solvent. The polar solvent additives systematically disrupted the templation and monomer aggregation processes in the prepolymerization solutions, and the extent of disruption was captured by the polymerization process. The changes in binding capacity within each series of polymers were measured, providing a quantitative assessment of the templation and monomer aggregation processes in the imprinted and non-imprinted polymers. The new method was tested using three different diphenyl phosphate imprinted polymers made using three different urea functional monomers. Each monomer had varying efficiencies of templation and monomer aggregation. The new MIP characterization method was found to have several advantages. To independently verify the new characterization method, the MIPs were also characterized using traditional binding isotherm analyses. The two methods appeared to give consistent conclusions. First, the polar solvent titration method is less susceptible to false positives in identifying the imprinting effect. Second, the method is able to differentiate and quantify changes in binding capacity, as measured at a fixed guest and polymer concentration, arising from templation or monomer aggregation processes in the prepolymerization solution. Third, the method was also easy to carry out, taking advantage of the ease of preparing MIPs.

  6. Dynamic Mechanical Characterization of Thin Film Polymer Nanocomposites

    NASA Technical Reports Server (NTRS)

    Herring, Helen M.; Gates, Thomas S. (Technical Monitor)

    2003-01-01

    Many new materials are being produced for aerospace applications with the objective of maximizing certain ideal properties without sacrificing others. Polymer composites in various forms and configurations are being developed in an effort to provide lighter weight construction and better thermal and electrical properties and still maintain adequate strength and stability. To this end, thin film polymer nanocomposites, synthesized for the purpose of influencing electrical conductivity using metal oxide particles as filler without incurring losses in mechanical properties, were examined to determine elastic modulus and degree of dispersion of particles. The effects of various metal oxides on these properties will be discussed.

  7. Synthesis and characterization thin films of conductive polymer (PANI) for optoelectronic device application

    NASA Astrophysics Data System (ADS)

    Jarad, Amer N.; Ibrahim, Kamarulazizi; Ahmed, Nasser M.

    2016-07-01

    In this work we report preparation and investigation of structural and optical properties of polyaniline conducting polymer. By using sol-gel in spin coating technique to synthesize thin films of conducting polymer polyaniline (PANI). Conducting polymer polyaniline was synthesized by the chemical oxidative polymerization of aniline monomers. The thin films were characterized by technique: Hall effect, High Resolution X-ray diffraction (HR-XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FE-SEM), and UV-vis spectroscopy. Polyaniline conductive polymer exhibit amorphous nature as confirmed by HR-XRD. The presence of characteristic bonds of polyaniline was observed from FTIR spectroscopy technique. Electrical and optical properties revealed that (p-type) conductivity PANI with room temperature, the conductivity was 6.289×10-5 (Ω.cm)-1, with tow of absorption peak at 426,805 nm has been attributed due to quantized size of polyaniline conducting polymer.

  8. Novel semiconducting polymers: Synthesis, characterization, and their application in organic electronics

    NASA Astrophysics Data System (ADS)

    Hubijar, Emir

    Conjugated polymers have attracted considerable attention as semiconducting materials in recent years due to their versatile electronic and optoelectronic applications. The main promise of conjugated polymers is not just attaining or exceeding the level of performance of silicon technologies but also producing electronic devices at a lower cost and enabling completely new device functionalities such as light weight, large surface area, mechanical flexibility, and optical transparency. Due to their broad potential, conjugated polymers have been incorporated in the wide range of applications, including polymer light-emitting diodes (LEDs), organic field-effect transistors (OFETs), and polymer solar cells (PSCs). Chapter 1 provides general information on conjugated polymers utilized in polymer light-emitting diodes (LEDs), polymer solar cells (PSCs) and organic field effect transistors (OFETs). It also includes brief description and schematic diagrams for each device configuration. Chapter 2 describes the synthesis, characterization and electronic properties of a novel symmetrical sulfone-substituted polyphenylene vinylene (SO 2EH-PPV) for applications in light-emitting devices. The sulfonyl functional group was directly attached to the polymer's backbone to increase the electron affinities of the polymer. The polymer was incorporated into a single layer PLED devices with the configuration of (ITO/ PEDOT:PSS/SO2EH-PPV polymer/Al). Chapter 3 focuses on the synthesis and color tuning of novel poly (fluorenevinylene-co-sulfonylphenylenevinylene) based copolymers for application in light-emitting diodes. New electroluminescent Poly(fluorenevinylene)-co-(sulfonylphenylenevinylene) random copolymers with different monomer feed ratios (PFV-SO2EH 10 and PFV-SO2EH 50) were synthesized via palladium-catalyzed Stille coupling reaction. Single layer stable PLED devices with the configuration of (ITO/PEDOT:PSS/PFV-SO 2EH 10 & PFV-SO2EH 50 polymer/Al) were fabricated exhibiting a

  9. Compositional and sensory characterization of red wine polymers.

    PubMed

    Wollmann, Nadine; Hofmann, Thomas

    2013-03-06

    After isolation from red wine by means of ultrafiltration and gel adsorption chromatography, the composition of the highly astringent tasting high-molecular weight polymers was analyzed by means of HPLC-MS/MS, HPLC-UV/vis, and ion chromatography after thiolytic, alkaline, and acidic depolymerization and, on the basis of the quantitative data obtained as well as model incubation experiments, key structural features of the red wine polymers were proposed. The structural backbone of the polymers seems to be comprised of a procyanidin chain with (-)-epicatechin, (+)-catechin, (-)-epicatechin-3-O-gallate units as extension and terminal units as well as (-)-epigallocatechin as extension units. In addition, acetaldehyde was shown to link different procyanidins at the A-ring via an 1,1-ethylene bridge and anthocyanins and pyranoanthocyanins were found to be linked to the procyanidin backbone via a C-C-linkage at position C(6) or C(8), respectively. Alkaline hydrolysis demonstrated the polymeric procyanidins to be esterified with various organic acids and phenolic acids, respectively. In addition, the major part of the polysaccharides present in the red wine polymeric fraction were found not to be covalently linked to procyanidins. Interestingly, sensory evaluation of individual fractions of the red wine polymers did not show any significant difference in the astringent threshold concentrations, nor in the astringency intensity in supra-threshold concentrations and demonstrated the mean degree of polymerization as well as the galloylation degree not to have an significant influence on the astringency perception.

  10. Characterizing Residuals in New and Aged Fluorotelomer Polymers in Soil

    EPA Science Inventory

    Fluorotelomer polymers (FTPs) comprise some of the major products of the fluorotelomer industry. FTPs impart anti-wetting and anti-staining properties which are invaluable to wide range of consumer products including clothing, upholstery, food packaging, and carpeting. FTPs retai...

  11. Fabrication of Au nanoparticle composite TiO2 shell arrays by controlled decomposition of polymer particles

    NASA Astrophysics Data System (ADS)

    Yan, Wei-Guo; Luo, Chun-Li; Zhao, Jian; Guo, Mei-Li; Ye, Qing; Li, Zu-Bin; Tian, Jian-Guo

    2014-11-01

    In the paper, the novel TiO2 nanoshell arrays coated with Au nanoparticles (NPs) were prepared by a simple and effective fabrication method with thermal decomposing polymer particles. Surface structure and composition of these arrays were evaluated by Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS), and X-ray photoelectron spectroscopy (XPS). The results indicated that TiO2 nanoshell coated with Au NPs was changed into Au@TiO2 composite NPs with the rise of annealing temperature. These novel nanostructures have the potential applications in some research fields, such as photocatalysis, single molecule detection, and novel optoelectronic devices.

  12. Synthesis and Characterization of Composite Membranes made of Graphene and Polymers of Intrinsic Microporosity

    DTIC Science & Technology

    2016-02-16

    polymers of intrinsic microporosity (PIMs), J. Membr. Sci. 401 (2012) 222e231. [20] T. Anokhina, A. Yushkin, P. Budd, A. Volkov, Application of PIM-1 for...characterization of composite membranes made of graphene and polymers of intrinsic microporosity Yuyoung Shin a, Eric Prestat b, Kai-Ge Zhou a, Patricia Gorgojo c...dx.doi.org/10.1016/j.carbon.2016.02.037 0008-6223/© 2016 The Authors. Published by Elseviea b s t r a c t Polymers of intrinsic microporosity (PIMs) are a

  13. Development and characterization of porous polypyrrole-polylactic acid electroactive polymer blends

    NASA Astrophysics Data System (ADS)

    Chan, Christine; Chan, Ellen; Naguib, Hani E.

    2009-03-01

    Conducting polymers have sparked much research interest due to their unique ability to be electrically stimulated. However, these polymers are very brittle and have poor mechanical properties. In order to improve upon its structural integrity, it can be blended with other host polymers that have better mechanical properties. These blended composites would then possess the benefits of conductive properties while having sufficient mechanical properties to be more suitable for practical applications. Polypyrrole-polylactic acid blends were processed using chemical oxidative polymerization and compression molding, followed by gas foaming and saturation techniques to create porous structures. Characterization of these porous blends included its physical, thermal, and mechanical properties.

  14. Dynamic nuclear polarization NMR spectroscopy allows high-throughput characterization of microporous organic polymers.

    PubMed

    Blanc, Frédéric; Chong, Samantha Y; McDonald, Tom O; Adams, Dave J; Pawsey, Shane; Caporini, Marc A; Cooper, Andrew I

    2013-10-16

    Dynamic nuclear polarization (DNP) solid-state NMR was used to obtain natural abundance (13)C and (15)N CP MAS NMR spectra of microporous organic polymers with excellent signal-to-noise ratio, allowing for unprecedented details in the molecular structure to be determined for these complex polymer networks. Sensitivity enhancements larger than 10 were obtained with bis-nitroxide radical at 14.1 T and low temperature (∼105 K). This DNP MAS NMR approach allows efficient, high-throughput characterization of libraries of porous polymers prepared by combinatorial chemistry methods.

  15. Characterization of pi-Conjugated Polymers for Transistor and Photovoltaic Applications

    NASA Astrophysics Data System (ADS)

    Paulsen, Bryan D.

    pi-Conjugated polymers represent a unique class of optoelectronic materials. Being polymers, they are solution processable and inherently "soft" materials. This makes them attractive candidates for the production of roll-to-roll printed electronic devices on flexible substrates. The optical and electronic properties of pi-conjugated polymers are synthetically tunable allowing material sets to be tailored to specific applications. Two of the most heavily researched applications are the thin film transistor, the building block of electronic circuits, and the bulk heterojunction solar cell, which holds great potential as a renewable energy source. Key to developing commercially feasible pi-conjugated polymer devices is a thorough understanding of the electronic structure and charge transport behavior of these materials in relationship with polymer structure. Here this structure property relationship has been investigated through electrical and electrochemical means in concert with a variety of other characterization techniques and device test beds. The tunability of polymer optical band gap and frontier molecular orbital energy level was investigated in systems of vinyl incorporating statistical copolymers. Energy levels and band gaps are crucial parameters in developing efficient photovoltaic devices, with control of these parameters being highly desirable. Additionally, charge transport and density of electronic states were investigated in pi-conjugated polymers at extremely high electrochemically induced charge density. Finally, the effects of molecular weight on pi-conjugated polymer optical properties, energy levels, charge transport, morphology, and photovoltaic device performance was examined.

  16. Electronic, chemical and structural characterization of CNTs grown by SiC surface decomposition

    NASA Astrophysics Data System (ADS)

    Policicchio, A.; Caruso, T.; Agostino, R. G.; Maccallini, E.; Chiarello, G.; Colavita, E.; Formoso, V.; Castriota, M.; Cazzanelli, E.

    2008-03-01

    The electronic, chemical and structural properties of Carbon NanoTubes (CNTs) synthesized by Silicon Carbide surface decomposition were analyzed by Scanning Electron Microscopy (SEM), Scanning Tunnelling Microscopy/Spectroscopy (STM/STS), Electron Energy Loss (EEL) and Raman spectroscopy. A clear relationship between the bonding features and the growth condition (temperature and growth time) is obtained. The morphology of the sample investigated by SEM reveals a well-packed and aligned structure of the CNTs. Different lengths of the CNTs are observed depending on the local temperature of the sample surface. The longest observed CNTs were 500/600 nm. The STS measurements show I-V diode-like characteristic curve which can be used, for instance, as an electron collector in solar cells applications. As a perspective metallic electrode, gold, will be deposited on top of the CNTs in the future, to collect the electron current and investigated by the same techniques.

  17. Characterizing Structure, Microclimate and Decomposition of Peatland, Beachfront, and Newly Logged Forest Edges in Southeastern Alaska

    NASA Astrophysics Data System (ADS)

    Concannon, Julie Ann

    In this study, I examined the forest structure, composition, microclimate, and decomposition of three common edge types in southeastern Alaska including; peatland, beachfront, and new clearcuts adjacent to productive western hemlock-Sitka spruce forests. Sites were located on 4 larger islands of the Alexander Archipelago in southeastern Alaska. The study was focussed on transects extending from the open area, through the forest boundary to 200 m into the forest. Twenty-two edges were examined during 1990 and 1991. Forest structure was unique for each edge type. Peatland -forest edges exhibit feathered transition of short and sparse tree growth to large dense old-growth western hemlock -Sitka spruce forests. Beachfront-forest edges were sealed at the boundary by a multi-layering of shrubs, small trees, mid-canopy trees, and some emergents. The transition to large productive old-growth was abrupt. Clearcut-forest edges were essentially old-growth forests opened up by logging. Average size of trees at the boundary was large but stand size and productivity decreased moving into the forest. Productive western hemlock-Sitka spruce associations were not apparent for a long distance into the forest. Herbaceous cover appeared to be directly linked to light levels along the forest transects. Because structure was so inherently different for each edge type, microclimatic gradients from open area to the forest interior environment varied with edge type. The strongest gradients were observed on sunny and extremely windy days. An edge index value (EIV) was calculated to differentiate edge-affected microclimate from interior environments. Edge type influenced forest microclimate such that; (1) Peatlands affected interior radiation and air temperature range for 120 m into the forest until interior environments were encountered. (2) Beachfront-forests were penetrated by ocean winds for up to 120 m however, other variables such as interior air temperature and relative humidity were

  18. Characterization and decomposition of self-aligned quadruple patterning friendly layout

    NASA Astrophysics Data System (ADS)

    Zhang, Hongbo; Du, Yuelin; Wong, Martin D. F.; Topaloglu, Rasit O.

    2012-03-01

    Self-aligned quadruple patterning (SAQP) lithography is one of the major techniques for the future process requirement after 16nm/14nm technology node. In this paper, based on the existing knowledge of current 193nm lithography and process flow of SAQP, we will process an early study on the definition of SAQP-friendly layout. With the exploration of the feasible feature regions and possible combinations of adjacent features, we will define several simple but important geometry rules to help define the SAQP-friendliness. Then, we will introduce a conflicting graph algorithm to generate the feature region assignment for SAQP decomposition. Our experimental results validate our SAQP-friendly layout definition, and basic circuit building blocks in the low level metal layer are analyzed.

  19. Identification and characterization of a vitamin D₃ decomposition product bactericidal against Helicobacter pylori.

    PubMed

    Hosoda, Kouichi; Shimomura, Hirofumi; Wanibuchi, Kiyofumi; Masui, Hisashi; Amgalanbaatar, Avarzed; Hayashi, Shunji; Takahashi, Takashi; Hirai, Yoshikazu

    2015-03-09

    This study demonstrated that the vitamin D₃ decomposition product VDP1 exerts an antibacterial action against Helicobacter pylori but not against other bacteria. Treatment with VDP1 induced a collapse of cell membrane structures of H. pylori and ultimately lysed the bacterial cells. A unique dimyristoyl phosphatidylethanolamine in the membrane lipid compositions contributed to the interaction of VDP1 with H. pylori cells. In separate experiments, VDP1 had no influence on the viability of the human cancer cell lines MKN45 and T47D and lacked any vitamin D₃-like hormonal action against the latter. In both (1)H and (13)C NMR analyses, the spectra patterns of VDP1 corresponded with those of Grundmann's ketone. These results suggest that VDP1 (or Grundmann's ketone-type indene compound) may become a fundamental structure for the development of new antibacterial substances with selective bactericidal action against H. pylori.

  20. Polymers.

    ERIC Educational Resources Information Center

    Tucker, David C.

    1986-01-01

    Presents an open-ended experiment which has students exploring polymer chemistry and reverse osmosis. This activity involves construction of a polymer membrane, use of it in a simple osmosis experiment, and application of its principles in solving a science-technology-society problem. (ML)

  1. Optical activity of transparent polymer layers characterized by spectral means

    NASA Astrophysics Data System (ADS)

    Cosutchi, Andreea Irina; Dimitriu, Dan Gheorghe; Zelinschi, Carmen Beatrice; Breaban, Iuliana; Dorohoi, Dana Ortansa

    2015-06-01

    The method based on the channeled spectrum, validated for inorganic optical active layers, is used now to determine the optical activity of some transparent polymer solutions in different solvents. The circular birefringence, the dispersion parameter and the specific rotation were estimated in the visible range by using the measurements of wavelengths in the channeled spectra of Hydroxypropyl cellulose in water, methanol and acetic acid. The experiments showed the specific rotation dependence on the polymer concentration and also on the solvent nature. The decrease of the specific rotation in the visible range with the increase in wavelength was evidenced. The method has some advantages as the rapidity of the experiments and the large spectral range in which it can be applied. One disadvantage is the fact that the channeled spectrum does not allow to establish the rotation sense of the electric field intensity.

  2. Fluorinated bottlebrush polymers based on poly(trifluoroethyl methacrylate): Synthesis and characterizations

    SciTech Connect

    Xu, Yuewen; Wang, Weiyu; Wang, Yangyang; Zhu, Jiahua; Uhrig, David; Lu, Xinyi; Keum, Jong Kahk; Mays, Jimmy W.; Hong, Kunlun

    2015-11-25

    Bottlebrush polymers are densely grafted polymers with long side-chains attached to a linear polymeric backbone. Their unusual structures endow them with a number of unique and potentially useful properties in solution, in thin films, and in bulk. Despite the many studies of bottlebrushes that have been reported, the structure–property relationships for this class of materials are still poorly understood. In this contribution, we report the synthesis and characterization of fluorinated bottlebrush polymers based on poly(2,2,2-trifluoroethyl methacrylate). The synthesis was achieved by atom transfer radical polymerization (ATRP) using an α-bromoisobutyryl bromide functionalized norbornene initiator, followed by ring-opening metathesis polymerization (ROMP) using a third generation Grubbs’ catalyst (G3). Rheological characterization revealed that the bottlebrush polymer backbones remained unentangled as indicated by the lack of a rubbery plateau in the modulus. By tuning the size of the backbone of the bottlebrush polymers, near-spherical and elongated particles representing single brush molecular morphologies were observed in a good solvent as evidenced by TEM imaging, suggesting a semi-flexible nature of their backbones in dilute solutions. Thin films of bottlebrush polymers exhibited noticeably higher static water contact angles as compared to that of the macromonomer reaching the hydrophobic regime, where little differences were observed between each bottlebrush polymer. Further investigation by AFM revealed that the surface of the macromonomer film was relatively smooth; in contrast, the surface of bottlebrush polymers displayed certain degrees of nano-scale roughness (Rq = 0.8–2.4 nm). The enhanced hydrophobicity of these bottlebrushes likely results from the preferential enrichment of the fluorine containing end groups at the periphery of the molecules and the film surface due to the side chain crowding effect. Furthermore, our results

  3. Fluorinated bottlebrush polymers based on poly(trifluoroethyl methacrylate): Synthesis and characterizations

    DOE PAGES

    Xu, Yuewen; Wang, Weiyu; Wang, Yangyang; ...

    2015-11-25

    Bottlebrush polymers are densely grafted polymers with long side-chains attached to a linear polymeric backbone. Their unusual structures endow them with a number of unique and potentially useful properties in solution, in thin films, and in bulk. Despite the many studies of bottlebrushes that have been reported, the structure–property relationships for this class of materials are still poorly understood. In this contribution, we report the synthesis and characterization of fluorinated bottlebrush polymers based on poly(2,2,2-trifluoroethyl methacrylate). The synthesis was achieved by atom transfer radical polymerization (ATRP) using an α-bromoisobutyryl bromide functionalized norbornene initiator, followed by ring-opening metathesis polymerization (ROMP) usingmore » a third generation Grubbs’ catalyst (G3). Rheological characterization revealed that the bottlebrush polymer backbones remained unentangled as indicated by the lack of a rubbery plateau in the modulus. By tuning the size of the backbone of the bottlebrush polymers, near-spherical and elongated particles representing single brush molecular morphologies were observed in a good solvent as evidenced by TEM imaging, suggesting a semi-flexible nature of their backbones in dilute solutions. Thin films of bottlebrush polymers exhibited noticeably higher static water contact angles as compared to that of the macromonomer reaching the hydrophobic regime, where little differences were observed between each bottlebrush polymer. Further investigation by AFM revealed that the surface of the macromonomer film was relatively smooth; in contrast, the surface of bottlebrush polymers displayed certain degrees of nano-scale roughness (Rq = 0.8–2.4 nm). The enhanced hydrophobicity of these bottlebrushes likely results from the preferential enrichment of the fluorine containing end groups at the periphery of the molecules and the film surface due to the side chain crowding effect. Furthermore, our results provide

  4. Synthesis and Physicochemical Characterization of Biobased, Compostable Polymers Containing Lignin

    NASA Astrophysics Data System (ADS)

    Harris, Stephanie Beret

    Biobased and compostable materials have gained in popularity as sustainable solutions for reducing waste and minimizing environmental impacts. Polylactide (PLA) continues to be a popular biobased polymer, but has limited use due to its brittleness, high vapor and ultraviolet (UV) light permeability. This study addresses these shortfalls through copolymerization of lactide (LA) with organosolv lignin from switchgrass (OSL) and delta-valerolactone (DVL) to produce 100 % biobased polymers with improved properties. Incorporation of hydrophobic OSL into poly(L-lactide) (PLLA), even in small quantities (up to 0.26%) resulted in a considerable decrease in water vapor transition rate (WVTR) of up to 64 %, nearly a 20 % decrease in UV light transmission, and slowing of hydrolytic degradation. Unfortunately, lignin appears to stop the chain propagation and effectively reduces overall M M w of the copolymer. Young's modulus for these copolymers is affected little as stress and strain decreased proportionally with the addition of OSL, resulting in a copolymer that is nearly equal to PLLA in stiffness. To improve elasticity, terpolymers of PLLA-DVL-OSL were explored. The addition of DVL to the polymerization was found to increase UV transmission rate, an effect that could be counteracted through OSL addition. PLLA-DVL co and terpolymers showed low Young's modulus, characteristic for polymers with elastomeric properties. WVTR was seen to decrease with the addition of DVL and was even further reduced through addition of OSL, resulting in an overall WVTR reduction of up to 79 %.

  5. Synthesis, characterization and application of epichlorohydrin-β-cyclodextrin polymer.

    PubMed

    Gidwani, Bina; Vyas, Amber

    2014-02-01

    Cyclodextrins, the macrocyclic compounds are renowned for their inclusion ability. Several chemical and polymerized derivatives of parent cyclodextrins are synthesized to improve the physicochemical/biopharmaceutical properties of drug and inclusion capacity of cyclodextrin. This review article recapitulates the potential aspects of polymerized water-soluble derivative of β-cyclodextrin viz. epichlorohydrin-β-cyclodextrin polymer in different areas of drug delivery. Polymerized cyclodextrin combines the advantage of the properties of polymer (high molecular weight and higher solubility) with the formation of inclusion complex with cyclodextrin. This justifies the superiority of polymerized cyclodextrin over parent cyclodextrin and some other chemically modified and non-polymerized derivatives. The use of polymerized cyclodextrin in various fields like biomedical, pharmaceutical and gene delivery is increasing day-by-day. β-Cyclodextrin-epichlorohydrin polymer is a high molecular weight compound, which acts as an effective drug carrier for enhancing the solubility and oral bioavailability of drugs along with the increase in therapeutic efficiency. The future panorama of polymerized cyclodextrins is quite bright as they can serve as useful multifunctional tools for pharmaceutical scientists to develop and optimize drug delivery through various routes. Also, no information concerning the regulatory status and toxicity of polymerized cyclodextrins is available. So, there is a need to focus on these critical issues for resolving the problems associated with the development and commercialization of drug products.

  6. Preparation and characterization of cross-linked composite polymer electrolytes

    SciTech Connect

    Hou, J.; Baker, G.L.

    1998-11-01

    Cross-linkable composite electrolytes were prepared from poly(ethylene glycol) dimethyl ether (PEGDME)-500, LiClO{sub 4}, fumed silica, and 10 wt % methyl, butyl, or octyl methacrylate. The silicas used were chemically modified by attaching methacrylate groups to the silica surface through C{sub 8} and C{sub 3} tethers. Before cross-linking, the electrolytes were thixotropic and had ionic conductivities of >2 {times} 10{sup {minus}4} S/cm. After ultraviolet (UV)-induced cross-linking, the electrolytes were rubbery and dimensionally stable, and the conductivities were unchanged. Conductivity, extraction, and thermal analysis data all support a model where the added methacrylate monomer and growing polymer chains phase separate from the electrolyte phase during photopolymerization to yield a methacrylate-rich silica/polymer phase and little or no polymer in the PEGDME-500 phase. Thus, the mechanical properties of the composite electrolyte and its ionic conductivity are decoupled and can be optimized independently.

  7. Fabrication and characterization of shape memory polymers at small-scales

    NASA Astrophysics Data System (ADS)

    Wornyo, Edem

    The objective of this research is to thoroughly investigate the shape memory effect in polymers, characterize, and optimize these polymers for applications in information storage systems. Previous research effort in this field concentrated on shape memory metals for biomedical applications such as stents. Minimal work has been done on shape memory polymers; and the available work on shape memory polymers has not characterized the behaviors of this category of polymers fully. Copolymer shape memory materials based on diethylene glycol dimethacrylate (DEGDMA) crosslinker, and tert butyl acrylate (tBA) monomer are designed. The design encompasses a careful control of the backbone chemistry of the materials. Characterization methods such as dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC); and novel nanoscale techniques such as atomic force microscopy (AFM), and nanoindentation are applied to this system of materials. Designed experiments are conducted on the materials to optimize spin coating conditions for thin films. Furthermore, the recovery, a key for the use of these polymeric materials for information storage, is examined in detail with respect to temperature. In sum, the overarching objectives of the proposed research are to: (i) Design shape memory polymers based on polyethylene glycol dimethacrylate (PEGDMA) and diethylene glycol dimethacrylate (DEGDMA) crosslinkers, 2-hydroxyethyl methacrylate (HEMA) and tert-butyl acrylate monomer (tBA). (ii) Utilize dynamic mechanical analysis (DMA) to comprehend the thermomechanical properties of shape memory polymers based on DEGDMA and tBA. (iii) Utilize nanoindentation and atomic force microscopy (AFM) to understand the nanoscale behavior of these SMPs, and explore the strain storage and recovery of the polymers from a deformed state. (iv) Study spin coating conditions on thin film quality with designed experiments. (iv) Apply neural networks and genetic algorithms to optimize these systems.

  8. Synthesis and characterization of phosphonate ester and phosphonic acid containing polymers and blends

    NASA Astrophysics Data System (ADS)

    Tamber, Harinder Singh

    1997-12-01

    Vinylbenzylphosphonate ester (VBP) was homopolymerized and copolymerized with methyl methacrylate and the reactivity ratio of this pair of monomers was calculated from Finneman-Ross and Kelen-Tudos methods. These methods provided identical values, which are rsb1 (VBP) = 1.23 and rsb2(MMA) = 0.43. The phosphonate ester group, -P = O(OEt)sb2; in VBP and poly(VBP-MMA) copolymers was hydrolysed to phosphonic acid, -P = O(OH)sb2; at room temperature to obtain vinylbenzylphosphonic acid (VBPa) and poly(VBPa-MMA) copolymers. sp1H, sp{13}C & sp{31}P NMR spectroscopy, DSC and FTIR were used to monitor the hydrolysis of these phosphorylated monomers and polymers. The glass transition temperature of PVBP was 13sp°C as compared to 198sp°C of PVBPa. The phosphoryl group in the parent polymers acts as a self plasticizing agent resulting in lower glass transition temperature, on the other hand inter and intra hydrogen bonding results in broad and high Tsbg in these hydrolysed polymers. VBP was also polymerized with BisGMA or TEGDM to low conversions. These oligomers were tested in vitro as potential adhesive materials for dental/enamel and composite resins. The phosphonate esters containing polymers show substantial capacity to dissolve the heavy metal salts, e.g., UOsb2(NO)sb3.6Hsb2O and thus provides radiopaque polymers. Excessive sorption of water lead to phase separation and, hence, loss of radiopacity. Thus, an alternate method of synthesis of radiopaque polymers is also described in which radiopacifying agent is covalently linked to polymer backbone. Styryldiphenylbismuth was prepared by the reaction of diphenylbismuthchloride and Grignard of p-bromostyrene, but some other by-products such as triphenylbismuth, distyrylphenyl bismoth were also obtained as revealed by reverse phase HPLC and the yield of the reaction was low. Iodinated monomers VBTIsb3 and IEMIsb3 were prepared by reacting VBC or IEM to triiodophenol in high yields. Decomposition kinetic analysis was done by

  9. Synthesis, Characterization and Catalytic Properties of Attapulgite/CeO2 Nanocomposite Films for Decomposition of Rhodamine B.

    PubMed

    Lu, Xiaowang; Li, Xiazhang; Qian, Junchao; Chen, Feng; Chen, Zhigang

    2015-08-01

    ATP(attapulgite)/CeO2 nanocomposite films were prepared on the glass substrates via a sol-gel and dip-coating route. The ATP/CeO2 nanocomposite films were characterized by Powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), transmission electron microscopy (TEM), atomic force microscopy (AFM) and fourier transform infrared spectroscopy (FT-IR). The results showed that the ATP/CeO2 nanocomposite films were free from cracks and the nanoparticles were attached onto the surface of attapulgite. The ATP/CeO2 nanocomposite films displayed excellent catalytic activity for decomposition of Rhodamine B. The COD (chemical oxygen demand) removal rate of rhodamine B using ATP/CeO2 nanocomposite films as catalyst reached as high as 94% when the weight ratio of ATP to CeO2 was 2:1.

  10. Channel polymer optical waveguides embedded in glass: Design, fabrication and characterization

    NASA Astrophysics Data System (ADS)

    Fernández Gavela, Adrián; García Granda, Miguel; Rodríguez García, José

    2015-09-01

    In this work, the design, fabrication and experimental evaluation of new channel polymer optical waveguides embedded in glass are reported. We show that high quality microchannels in glass, without roughness on the walls, make possible the fabrication of new channel optical waveguides by filling the microchannels with a polymer. Guided light through those new optical waveguides is demonstrated experimentally. The commercial software OlympIOs was used to design multimode and monomode channel polymer optical waveguides. The microchannels in glass substrate were fabricated by using a laser lithography system and wet-etching procedures. The spin-coating technique was applied to deposit the polymer inside the microchannels. The end-coupling method was implemented for the waveguides characterization. Theoretical and experimental results have confirmed light confinement as well as guided modes propagation by these new channel optical waveguides.

  11. Synthesis and characterization of porous polyaniline conductive polymers

    NASA Astrophysics Data System (ADS)

    Price, Aaron D.; Naguib, Hani E.

    2007-04-01

    Polyaniline conductive polymers exhibit great potential for linear actuator applications. Many recent studies report methods to develop polyaniline-based materials with increased mechanical properties, electrical conductivity, and faster response time during actuation. In this study, porous blends of poly(methylmethacrylate) and polyaniline are processed using a two phase batch foaming setup. The effect of materials, processing, and system parameters on the physical properties of the resulting cellular structure are investigated. Hence, the effect of density and cell morphology on the electrical conductivity is elucidated.

  12. Surface characterization of LDEF carbon fiber/polymer matrix composites

    NASA Technical Reports Server (NTRS)

    Grammer, Holly L.; Wightman, James P.; Young, Philip R.; Slemp, Wayne S.

    1995-01-01

    XPS (x-ray photoelectron spectroscopy) and SEM (scanning electron microscopy) analysis of both carbon fiber/epoxy matrix and carbon fiber/polysulfone matrix composites revealed significant changes in the surface composition as a result of exposure to low-earth orbit. The carbon 1s curve fit XPS analysis in conjunction with the SEM photomicrographs revealed significant erosion of the polymer matrix resins by atomic oxygen to expose the carbon fibers of the composite samples. This erosion effect on the composites was seen after 10 months in orbit and was even more obvious after 69 months.

  13. Laboratory bench for the characterization of triboelectric properties of polymers

    NASA Astrophysics Data System (ADS)

    Neagoe, Bogdan; Prawatya, Yopa; Zeghloul, Thami; Souchet, Dominique; Dascalescu, Lucian

    2015-10-01

    The use of polymers as materials for sliding machine components is due to their low cost, ease of manufacturing, as well as appropriate mechanical and thermal properties. The aim of this paper is to present the experimental bench designed for the study of the triboelectric charge generated in sliding conformal contacts between flat polymer materials. The experiments were performed with 4-mm-thick samples of polystyrene and 5-mm-thick samples of poly-vinyl-chloride.The normal contact force can be adjusted using an appropriate control system and measured by a force sensor (± 50 N). The translational back-and-forth motion of the samples is produced by a crank-shaft system that generates a sinusoidal translational speed profile, with amplitudes between 12 and 50 mm/s, for strokes of 36 to 60 mm. The distribution of charge at the surface of the samples is measured by the capacitive probe of an electrostatic voltmeter (± 10 kV). The experiments pointed out that this bench enables the evaluation of the non-uniformity of the electric charge accumulated on the sliding bodies and the study of the correlations that might exists between this charge and the external forces applied to the contact.

  14. Characterization of non-Fickian moisture absorption in thermosetting polymers

    NASA Astrophysics Data System (ADS)

    Guloglu, Gorkem E.; Altan, M. Cengiz

    2015-05-01

    A recently developed moisture absorption model for thermosetting polymers that combines the non-Fickian, diffusion hindrance effects and three-dimensional anisotropy is introduced. The hindered diffusion model is shown to predict both short term Fickian and long term anomalous moisture absorption behavior often observed in thermosetting polymers and their composites. The salient characteristics of long term moisture uptake such as the equilibrium moisture content and the effect of non-Fickian phenomena are presented. Anomalous moisture concentration profiles predicted by the two-dimensional solution of hindered diffusion model are demonstrated for various cases, including the through-the-thickness moisture profile of a 40-ply, quartz/bismaleimide (BMI) composite laminate. The effects of diffusion hindrance and anisotropy on the two-dimensional, through-the-thickness concentration profiles are illustrated. The moisture absorption parameters for an EPON 862 epoxy laminate are recovered from the experimental moisture absorption data. The hindered diffusion model is shown to accurately predict the moisture uptake of EPON 862 over the complete absorption time period. The non-Fickian effects governed by the hindrance coefficient are identified for both EPON 862 and quartz/BMI composite laminate. It is shown that the quartz/BMI laminate displays significant non-Fickian behavior compared to EPON 862 epoxy resin.

  15. Synthesis and characterization of thermally responsive polymer layers

    NASA Astrophysics Data System (ADS)

    Seeber, Michael

    Future devices such as biomedical and microfluidic devices, to a large extent, will depend on the interactions between the device surfaces and the contacting liquid. Further, biological liquids containing proteins call for controllable interactions between devices and such proteins, however the bulk material must retain the inherent mechanical properties from which the device was fabricated from. It is well known that surface modification is a suitable technique to tune the surface properties without sacrificing the bulk properties of the substrate. In the present study, surface properties were modified through temperature responsive polymer layers. After the modification, the surfaces gained switchability toward protein interaction as well as surface wettability properties. Poly(N-isopropylacrylamide) (PNIPAM), a well studied thermo-responsive polymer was utilized in the subsequent work. Firstly, thermally responsive brushes made from well defined block copolymers incorporating NIPAM and the surface reactive monomer, glycidyl methacrylate (GMA) were fabricated in a single step process. Reaction of the PGMA block with surface hydroxyl groups anchors the polymers to the surface yet allows PNIPAM to assemble at the interface at high enough concentration to exhibit thermally responsive properties in aqueous solutions. Surface properties of the resulting brushes prepared the 1-step process are compared to characteristics of PNIPAM brushes synthesized by already established methods. The thickness, swelling, and protein adsorption of the PNIPAM films were studied by ellipsometry. Chemical composition of the layer was studied by angle-resolved x-ray photoelectron spectroscopy. Film morphologies and forces of adhesion to fibrinogen were examined using atomic force microscopy (AFM) tapping mode and colloidal probe technique. Block copolymer (BCP) and conventional brush films were abraded and subsequently examined for changes in thermally responsive behavior. The results

  16. Orthogonal Supramolecular Polymer Formation on Highly Oriented Pyrolytic Graphite (HOPG) Surfaces Characterized by Scanning Probe Microscopy.

    PubMed

    Gong, Yongxiang; Zhang, Siqi; Geng, Yanfang; Niu, Chunmei; Yin, Shouchun; Zeng, Qingdao; Li, Min

    2015-10-27

    Formation of an orthogonal supramolecular polymer on a highly oriented pyrolytic graphite (HOPG) surface was demonstrated for the first time by means of scanning probe microscopy (SPM). Atomic force microscopy (AFM) was employed to characterize the variation of both the thickness and the topography of the film formed from (1) monomer 1, (2) monomer 1/Zn(2+), and (3) monomer 1/Zn(2+)/cross-linker 2, respectively. Scanning tunneling microscopy (STM) was used to monitor the self-assembly behavior of monomer 1 itself, as well as 1/Zn(2+) ions binary system on graphite surface, further testifying for the formation of linear polymer via coordination interaction at the single molecule level. These results, given by the strong surface characterization tool of SPM, confirm the formation of the orthogonal polymer on the surface of graphite, which has great significance in regard to fabricating a complex superstructure on surfaces.

  17. Formation and Characterization of Stacked Nanoscale Layers of Polymers and Silanes on Silicon Surfaces

    NASA Astrophysics Data System (ADS)

    Ochoa, Rosie; Davis, Brian; Conley, Hiram; Hurd, Katie; Linford, Matthew R.; Davis, Robert C.

    2008-10-01

    Chemical surface patterning at the nanoscale is a critical component of chemically directed assembly of nanoscale devices or sensitive biological molecules onto surfaces. Complete and consistent formation of nanoscale layers of silanes and polymers is a necessary first step for chemical patterning. We explored methods of silanizing silicon substrates for the purpose of functionalizing the surfaces. The chemical functionalization, stability, flatness, and repeatability of the process was characterized by use of ellipsometry, water contact angle, and Atomic Force Microscopy (AFM). We found that forming the highest quality functionalized surfaces was accomplished through use of chemical vapor deposition (CVD). Specifically, surfaces were plasma cleaned and hydrolyzed before the silane was applied. A polymer layer less then 2 nm in thickness was electrostatically bound to the silane layer. The chemical functionalization, stability, flatness, and repeatability of the process was also characterized for the polymer layer using ellipsometry, water contact angle, and AFM.

  18. Synthesis and characterization of soluble conducting polymers and conducting adhesives

    NASA Astrophysics Data System (ADS)

    Oztemiz, Serhan

    With the demanding nature of the technology today, scientists are looking for new materials in order to decrease the cost, increase the efficiency of the use of the materials, and decrease time-consuming steps in order to increase the speed of production. New materials are being studied to decrease the weight of cars, planes and space vehicles; surface properties are being modified to decrease the drag coefficient; new technologies are being introduced for speeding up applications in production and assembly lines. In this research we address the needs of different technological applications from a conductivity perspective. In the first part of the thesis, the synthesis of soluble conducting polymers in order to make them more processable for potential electronic and photovoltaic applications is presented. Soluble conducting polymers of 3-hexylthiophene, 3-octylthiophene, 3-decylthiophene and 3-dodecylthiophene were synthesized electrochemically and thus, doped during synthesis. It was found that the conductivities; molecular weights and degrees of polymerization of the polymers strongly depend on the side chain's length. The substitution of alkyl side chains decreases the reactivity of the growing chain, and with an increasing side-chain length, all of these properties show a decrease. The hexyl substituent, being the shortest of the four side chains, causes the least distortion in the background, has the highest conjugation, and has the highest shift in the UV spectrum when it polymerizes. As the length of the side chain increases, the shift in the UV spectrum decreases, too. Decrease in the pi-stacking, conjugation and delocalization decreases the conductivity. This gives the material an opportunity to be used in photovoltaic applications. In the second part of the thesis, a conducting adhesive formulation that eliminates the need for heat or other expensive and rather bothersome application methods to activate the adhesive is investigated. Using the quick

  19. Interface Characterization in Fiber-Reinforced Polymer-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Naya, F.; Molina-Aldareguía, J. M.; Lopes, C. S.; González, C.; LLorca, J.

    2017-01-01

    A novel methodology is presented and applied to measure the shear interface strength of fiber-reinforced polymers. The strategy is based in fiber push-in tests carried out on the central fiber of highly-packed fiber clusters with hexagonal symmetry, and it is supported by a detailed finite element analysis of the push-in test to account for the influence of hygrothermal residual stresses, fiber constraint and fiber anisotropy on the interface strength. Examples of application are presented to determine the shear interface strength in carbon and glass fiber composites reinforced with either thermoset or thermoplastic matrices. In addition, the influence of the environment (either dry or wet conditions) on the interface strength in C/epoxy composites is demonstrated.

  20. Preparation and Characterization of Novel Polymer/Silicate Nanocomposites

    SciTech Connect

    Harrup, Mason Kurt; Wertsching, Alan Kevin; Jones, Michael Glen

    2002-01-01

    Nanocomposite materials with an inorganic glass and an organic polymer constitute a relatively new and unique area in material science. The term “ormocers”, “ormosils” and “ceramers” are often utilized to describe this class of nanocomposite (1, 2). By combining at the molecular level inorganic and organic polymeric material a blending of unique physical properties can be achieved. The value in these materials is apparent, from fiber optics to paints these materials may provide the requisite physical properties to achieve the next technological advance. There are several different ways of synthesizing this class of nanocomposite; therefore a means of classification is necessary. Most developed nomenclature is based on synthetic techniques; Wilkes has a relatively recent and exhaustive categorization (3). However we chose to classify these materials upon a simpler system first suggested by Novak (4). Five categories cover the majority of composites synthesized with more recent techniques being modifications or combinations from this list.

  1. Design, fabrication and characterization of an arrayable all-polymer microfluidic valve employing highly magnetic rare-earth composite polymer

    NASA Astrophysics Data System (ADS)

    Rahbar, Mona; Shannon, Lesley; Gray, Bonnie L.

    2016-05-01

    We present a new magnetically actuated microfluidic valve that employs a highly magnetic composite polymer (M-CP) containing rare-earth hard-magnetic powder for its actuating element and for its valve seat. The M-CP offers much higher magnetization compared to the soft-magnetic, ferrite-based composite polymers typically used in microfluidic applications. Each valve consists of a permanently magnetized M-CP flap and valve seat mounted on a microfluidic channel system fabricated in poly(dimethylsiloxane) (PDMS). Each valve is actuated under a relatively small external magnetic field of 80 mT provided by a small permanent magnet mounted on a miniature linear actuator. The performance of the valve with different flap thicknesses is characterized. In addition, the effect of the magnetic valve seat on the valve’s performance is also characterized. It is experimentally shown that a valve with a 2.3 mm flap thickness, actuated under an 80 mT magnetic field, is capable of completely blocking liquid flow at a flow rate of 1 ml min-1 for pressures up to 9.65 kPa in microfluidic channels 200 μm wide and 200 μm deep. The valve can also be fabricated into an array for flow switching between multiple microfluidic channels under continuous flow conditions. The performance of arrays of valves for flow routing is demonstrated for flow rates up to 5 ml min-1 with larger microfluidic channels of up to 1 mm wide and 500 μm deep. The design of the valves is compatible with other commonly used polymeric microfluidic components, as well as other components that use the same novel permanently magnetic composite polymer, such as our previously reported cilia-based mixing devices.

  2. Fabrication and characterization of ultrahigh-volume- fraction aligned carbon nanotube-polymer composites.

    PubMed

    Wardle, Brian L; Saito, Diego S; García, Enrique J; Hart, A John; de Villoria, Roberto Guzmán; Verploegen, Eric A

    2008-07-17

    Aligned CNT nanocomposites with variable volume fraction, up to 20%, are demonstrated. Biaxial mechanical densification of aligned CNT forests, followed by capillarity-driven wetting using unmodified aerospace-grade polymers, creates centimeter-scale specimens. Characterizations confirm CNT alignment and dispersion in the thermosets, providing a useful platform for controlled nanoscale interaction and nanocomposite property studies that emphasize anisotropy.

  3. Synthesis and characterization of nanoscale polymer films grafted to metal surfaces

    NASA Astrophysics Data System (ADS)

    Galabura, Yuriy

    Anchoring thin polymer films to metal surfaces allows us to alter, tune, and control their biocompatibility, lubrication, friction, wettability, and adhesion, while the unique properties of the underlying metallic substrates, such as magnetism and electrical conductivity, remain unaltered. This polymer/metal synergy creates significant opportunities to develop new hybrid platforms for a number of devices, actuators, and sensors. This present work focused on the synthesis and characterization of polymer layers grafted to the surface of metal objects. We report the development of a novel method for surface functionalization of arrays of high aspect ratio nickel nanowires/micronails. The polymer "grafting to" technique offers the possibility to functionalize different segments of the nickel nanowires/micronails with polymer layers that possess antagonistic (hydrophobic/hydrophilic) properties. This method results in the synthesis of arrays of Ni nanowires and micronails, where the tips modified with hydrophobic layer (polystyrene) and the bottom portions with a hydrophilic layer (polyacrylic acid). The developed modification platform will enable the fabrication of switchable field-controlled devices (actuators). Specifically, the application of an external magnetic field and the bending deformation of the nickel nanowires and micronails will make initially hydrophobic surface more hydrophilic by exposing different segments of the bent nanowires/micronails. We also investigate the grafting of thin polymer films to gold objects. The developed grafting technique is employed for the surface modification of Si/SiO2/Au microprinted electrodes. When electronic devices are scaled down to submicron sizes, it becomes critical to obtain uniform and robust insulating nanoscale polymer films. Therefore, we address the electrical properties of polymer layers of poly(glycidyl methacrylate) (PGMA), polyacrylic acid (PAA), poly(2-vinylpyridine) (P2VP), and polystyrene (PS) grafted to

  4. Effective characterization of polymer residues on two-dimensional materials by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Park, Ji-Hoon; Choi, Soo Ho; Chae, Won Uk; Stephen, Boandoh; Park, Hyeon Ki; Yang, Woochul; Kim, Soo Min; Lee, Joo Song; Kim, Ki Kang

    2015-12-01

    Large-area two-dimensional (2D) materials grown by chemical vapor deposition need to be transferred onto a target substrate for real applications. Poly(methyl methacrylate) as a supporting layer is widely used during the transfer process and removed after finishing it. However, it is a challenge to diminish the polymer layer completely. It is necessary to readily characterize the polymer residues on 2D materials to facilitate the removal process. Here, we report a method that characterizes the polymer residues on 2D materials by tracking the presence of G-band of amorphous carbons (a-Cs) in the Raman spectrum after forming carbonized a-Cs through thermal annealing. The 13C-graphene is employed to separate the Raman signal G-band between 12C-a-Cs and 13C-graphene in the Raman spectrum. The residence of the polymer residues is clearly confirmed by the different Raman signals of two different isotopes (12C and 13C) due to differences in mass. Our effective method recognizes that while the polymer residue is not easily removed on graphene, those on hexagonal boron nitride and molybdenum disulfide are almost diminished under optimum thermal annealing conditions. Our method will not only contribute to the development of a new transfer process, but also help to achieve a clean surface of 2D materials.

  5. Recent progress of the characterization of oppositely charged polymer/surfactant complex in dilution deposition system.

    PubMed

    Miyake, M

    2017-01-01

    A mixture of oppositely charged polymer and surfactants changes the solubilized state, having a complex precipitation region at the composition of electric neutralization. This complex behavior has been applied to surface modification in the fields of health care and cosmetic products such as conditioning shampoos, as a dilution-deposition system in which the polymer/surfactant mixture at the higher surfactant concentration precipitates the insoluble complex by dilution. A large number of studies over many years have revealed the basic coacervation behavior and physicochemical properties of complexes. However, the mechanism by which a precipitated complex performs surface modification is not well understood. The precipitation region and the morphology of precipitated complex that are changed by molecular structure and additives affect the performance. Hydrophilic groups such as the EO unit in polymers and surfactants, the mixing of nonionic or amphoteric surfactant and nonionic polymer, and the addition of low polar solvent influence the complex precipitation region. Furthermore, the morphology of precipitated complex is formed by crosslinking and aggregating among polymers in the dilution process, and characterizes the performance of products. The polymer chain density in precipitated complex is determined by the charges of both the polymer and surfactant micelle and the conformation of polymer. As a result, the morphology of precipitated complexes is changed from a closely packed film to looser meshes, and/or to small particles, and it is possible for the morphology to control the rheological properties and the amount of adsorbed silicone. In the future, further investigation of the relationships between the morphology and performance is needed.

  6. Characterization of explosives processing waste decomposition due to composting. Phase 2, Final report

    SciTech Connect

    Griest, W.H.; Tyndall, R.L.; Stewart, A.J.; Ho, C.H.; Ironside, K.S.; Caton, J.E.; Caldwell, W.M.; Tan, E.

    1991-11-01

    Static pile and mechanically stirred composts generated at the Umatilla Army Depot Activity in a field composting optimization study were chemically and toxicologically characterized to provide data for the evaluation of composting efficiency to decontaminate and detoxify explosives-contaminated soil. Characterization included determination of explosives and 2,4,6,-trinitrotoluene metabolites in composts and their EPA Synthetic Precipitation Leaching Procedure Leachates, leachate toxicity to Ceriodaphnia Dubia and mutagenicity of the leachates and organic solvent extracts of the composts to Ames bacterial strains TA-98 and TA-100. The main conclusion from this study is that composting can effectively reduce the concentrations of explosives and bacterial mutagenicity in explosives -- contaminated soil, and can reduce the aquatic toxicity of leachable compounds. Small levels of explosive and metabolites, bacterial mutagenicity, and leachable aquatic toxicity remain after composting. The ultimate fate of the biotransformed explosives, and the source(s) of residual toxicity and mutagenicity remain unknown.

  7. Characterization of explosives processing waste decomposition due to composting. Final report

    SciTech Connect

    Griest, W.H.; Stewart, A.J.; Ho, C.H.; Tyndall, R.L.; Vass, A.A.; Caton, J.E.; Caldwell, W.M.

    1994-09-01

    The objective of this work was to provide data and methodology assisting the transfer and acceptance of composting technology for the remediation of explosives-contaminated soils and sediments. Issues and activities addressed included: (a) chemical and toxicological characterization of compost samples from new field composting experiments, and the environmental availability of composting efficiency by isolation of bacterial consortia and natural surfactants from highly efficient composts, and (c) improved assessment of compost product suitability for land application.

  8. Interpenetrating phase ceramic/polymer composite coatings: Fabrication and characterization

    NASA Astrophysics Data System (ADS)

    Craig, Bradley Dene

    The goals of this thesis research were to fabricate interpenetrating phase composite (IPC) ceramic/polymer coatings and to investigate the effect of the interconnected microstructure on the physical and wear properties of the coatings. IPC coatings with an interpenetrating phase microstructure were successfully fabricated by first forming a porous ceramic with an interconnected microstructure using a chemical bonding route (mainly reacting alpha-alumina (0.3 mum) with orthophosphoric acid to form a phosphate bond). Porosity within these ceramic coatings was easily controlled between 20 and 50 vol. % by phosphoric acid addition, and was measured by a new porosity measurement technique (thermogravimetric volatilization of liquids, or TVL) which was developed. The resulting ceramic preforms were infiltrated with a UV and thermally curable cycloaliphatic epoxide resin and cured. This fabrication route resulted in composite coatings with thicknesses ranging from ˜1mum to 100 mum with complete filling of open pore space. The physical properties of the composite coatings, including microhardness, flexural modulus and wear resistance, were evaluated as a function of processing variables, including orthophosphoric acid content and ceramic phase firing temperature, which affected the microstructure and interparticulate bonding between particles in the coatings. For example, microhardness increased from ˜30 on the Vicker's scale to well over 200 as interparticulate bonding was increased in the ceramic phase. Additionally, Taber wear resistance in the best TPC coatings was found to approach that of fully-densified alumina under certain conditions. Several factors were found to influence the wear mechanism in the IPC coating materials. Forming strong connections between ceramic particles led to up to an order of magnitude increase in the wear resistance. Additionally, coating microhardness and ceramic/polymer interfacial strength were studied and found to be important in

  9. Characterization of selected LDEF polymer matrix resin composite materials

    NASA Technical Reports Server (NTRS)

    Young, Philip R.; Slemp, Wayne S.; Witte, William G., Jr.; Shen, James Y.

    1991-01-01

    The characterization of selected graphite fiber reinforced epoxy (934 and 5208) and polysulfone (P1700) matrix resin composite materials which received 5 years and 10 months of exposure to the LEO environment on the Long Duration Exposure Facility is reported. Resin loss and a decrease in mechanical performance as well as dramatic visual effects were observed. However, chemical characterization including infrared, thermal, and selected solution property measurements showed that the molecular structure of the polymeric matrix had not changed significantly in response to this exposure. The potential effect of a silicon-containing molecular contamination of these specimens is addressed.

  10. Optical characterization of phase transitions in pure polymers and blends

    SciTech Connect

    Mannella, Gianluca A.; Brucato, Valerio; La Carrubba, Vincenzo

    2015-12-17

    To study the optical properties of polymeric samples, an experimental apparatus was designed on purpose and set up. The sample is a thin film enclosed between two glass slides and a PTFE frame, with a very thin thermocouple placed on sample for direct temperature measurement. This sample holder was placed between two aluminum slabs, equipped with a narrow slit for optical measurements and with electrical resistances for temperature control. Sample was enlightened by a laser diode, whereas transmitted light was detected with a photodiode. Measurements were carried out on polyethylene-terephtalate (PET) and two different polyamides, tested as pure polymers and blends. The thermal history imposed to the sample consisted in a rapid heating from ambient temperature to a certain temperature below the melting point, a stabilization period, and then a heating at constant rate. After a second stabilization period, the sample was cooled. The data obtained were compared with DSC measurements performed with the same thermal history. In correspondence with transitions detected via DSC (e.g. melting, crystallization and cold crystallization), the optical signal showed a steep variation. In particular, crystallization resulted in a rapid decrease of transmitted light, whereas melting gave up an increase of light transmitted by the sample. Further variations in transmitted light were recorded for blends, after melting: those results may be related to other phase transitions, e.g. liquid-liquid phase separation. All things considered, the apparatus can be used to get reliable data on phase transitions in polymeric systems.

  11. Characterization of a boron carbide-based polymer neutron sensor

    NASA Astrophysics Data System (ADS)

    Tan, Chuting; James, Robinson; Dong, Bin; Driver, M. Sky; Kelber, Jeffry A.; Downing, Greg; Cao, Lei R.

    2015-12-01

    Boron is used widely in thin-film solid-state devices for neutron detection. The film thickness and boron concentration are important parameters that relate to a device's detection efficiency and capacitance. Neutron depth profiling was used to determine the film thicknesses and boron-concentration profiles of boron carbide-based polymers grown by plasma enhanced chemical vapor deposition (PECVD) of ortho-carborane (1,2-B10C2H12), resulting in a pure boron carbide film, or of meta-carborane (1,7-B10C2H12) and pyridine (C5H5N), resulting in a pyridine composite film, or of pyrimidine (C4H4N2) resulting in a pure pyrimidine film. The pure boron carbide film had a uniform surface appearance and a constant thickness of 250 nm, whereas the thickness of the composite film was 250-350 nm, measured at three different locations. In the meta-carborane and pyridine composite film the boron concentration was found to increase with depth, which correlated with X-ray photoelectron spectroscopy (XPS)-derived atomic ratios. A proton peak from 14N (n,p)14C reaction was observed in the pure pyrimidine film, indicating an additional neutron sensitivity to nonthermal neutrons from the N atoms in the pyrimidine.

  12. Optical characterization of phase transitions in pure polymers and blends

    NASA Astrophysics Data System (ADS)

    Mannella, Gianluca A.; Brucato, Valerio; La Carrubba, Vincenzo

    2015-12-01

    To study the optical properties of polymeric samples, an experimental apparatus was designed on purpose and set up. The sample is a thin film enclosed between two glass slides and a PTFE frame, with a very thin thermocouple placed on sample for direct temperature measurement. This sample holder was placed between two aluminum slabs, equipped with a narrow slit for optical measurements and with electrical resistances for temperature control. Sample was enlightened by a laser diode, whereas transmitted light was detected with a photodiode. Measurements were carried out on polyethylene-terephtalate (PET) and two different polyamides, tested as pure polymers and blends. The thermal history imposed to the sample consisted in a rapid heating from ambient temperature to a certain temperature below the melting point, a stabilization period, and then a heating at constant rate. After a second stabilization period, the sample was cooled. The data obtained were compared with DSC measurements performed with the same thermal history. In correspondence with transitions detected via DSC (e.g. melting, crystallization and cold crystallization), the optical signal showed a steep variation. In particular, crystallization resulted in a rapid decrease of transmitted light, whereas melting gave up an increase of light transmitted by the sample. Further variations in transmitted light were recorded for blends, after melting: those results may be related to other phase transitions, e.g. liquid-liquid phase separation. All things considered, the apparatus can be used to get reliable data on phase transitions in polymeric systems.

  13. The design and characterization of protein based block polymers

    NASA Astrophysics Data System (ADS)

    Haghpanah, Jennifer Shorah

    Over the past decades, protein engineering has provided noteworthy advances in basic science as well as in medicine and industry. Protein engineers are currently focusing their efforts on developing elementary rules to design proteins with a specific structure and function. Proteins derived from natural sources have been used generate a plethora of materials with remarkable structural and functional properties. In the first chapter, we show how we can fabricate protein polymers comprised of two different self-assembling domains (SADs). From our studies, we discover that SADs in different orientations have a large impact on their overall microscopic and macroscopic features. In the second chapter, we explore the impact of cellulose (Tc) on the diblocks EC and CE. We discover that Tc is able to selectively impact the mechanical propertied of CE because CE has smaller particle sizes and more E domain exposed on its surface at RT. In the third chapter, we appended an extra C domain to CE to generate CEC with improved mechanical properties, structure and small molecule recognition.

  14. Predicting X-ray absorption spectra of semiconducting polymers for electronic structure and morphology characterization

    NASA Astrophysics Data System (ADS)

    Su, Gregory; Patel, Shrayesh; Pemmaraju, C. Das; Kramer, Edward; Prendergast, David; Chabinyc, Michael

    2015-03-01

    Core-level X-ray absorption spectroscopy (XAS) reveals important information on the electronic structure of materials and plays a key role in morphology characterization. Semiconducting polymers are the active component in many organic electronics. Their electronic properties are critically linked to device performance, and a proper understanding of semiconducting polymer XAS is crucial. Techniques such as resonant X-ray scattering rely on core-level transitions to gain materials contrast and probe orientational order. However, it is difficult to identify these transitions based on experiments alone, and complementary simulations are required. We show that first-principles calculations can capture the essential features of experimental XAS of semiconducting polymers, and provide insight into which molecular model, such as oligomers or periodic boundary conditions, are best suited for XAS calculations. Simulated XAS can reveal contributions from individual atoms and be used to visualize molecular orbitals. This allows for improved characterization of molecular orientation and scattering analysis. These predictions lay the groundwork for understanding how chemical makeup is linked to electronic structure, and to properly utilize experiments to characterize semiconducting polymers.

  15. Computational Reduction of Specimen Noise to Enable Improved Thermography Characterization of Flaws in Graphite Polymer Composites

    NASA Technical Reports Server (NTRS)

    Winfree, William P.; Howell, Patricia A.; Zalameda, Joseph N.

    2014-01-01

    Flaw detection and characterization with thermographic techniques in graphite polymer composites are often limited by localized variations in the thermographic response. Variations in properties such as acceptable porosity, fiber volume content and surface polymer thickness result in variations in the thermal response that in general cause significant variations in the initial thermal response. These result in a "noise" floor that increases the difficulty of detecting and characterizing deeper flaws. A method is presented for computationally removing a significant amount of the "noise" from near surface porosity by diffusing the early time response, then subtracting it from subsequent responses. Simulations of the thermal response of a composite are utilized in defining the limitations of the technique. This method for reducing the data is shown to give considerable improvement characterizing both the size and depth of damage. Examples are shown for data acquired on specimens with fabricated delaminations and impact damage.

  16. Modern mass spectrometry in the characterization and degradation of biodegradable polymers.

    PubMed

    Rizzarelli, Paola; Carroccio, Sabrina

    2014-01-15

    In the last decades, the solid-waste management related to the extensively growing production of plastic materials, in concert with their durability, have stimulated increasing interest in biodegradable polymers. At present, a variety of biodegradable polymers has already been introduced onto the market and can now be competitive with non biodegradable thermoplastics in different fields (packaging, biomedical, textile, etc.). However, a significant economical effort is still directed in tailoring structural properties in order to further broaden the range of applications without impairing biodegradation. Improving the performance of biodegradable materials requires a good characterization of both physico-chemical and mechanical parameters. Polymer analysis can involve many different features including detailed characterization of chemical structures and compositions as well as average molecular mass determination. It is of outstanding importance in troubleshooting of a polymer manufacturing process and for quality control, especially in biomedical applications. This review describes recent trends in the structural characterization of biodegradable materials by modern mass spectrometry (MS). It provides an overview of the analytical tools used to evaluate their degradation. Several successful applications of MALDI-TOF MS (matrix assisted laser desorption ionization time of flight) and ESI MS (electrospray mass spectrometry) for the determination of the structural architecture of biodegradable macromolecules, including their topology, composition, chemical structure of the end groups have been reported. However, MS methodologies have been recently applied to evaluate the biodegradation of polymeric materials. ESI MS represents the most useful technique for characterizing water-soluble polymers possessing different end group structures, with the advantage of being easily interfaced with solution-based separation techniques such as high-performance liquid

  17. Synthesis and characterization of a hyper-branched water-soluble β-cyclodextrin polymer

    PubMed Central

    Caldera, Fabrizio; Cavalli, Roberta; Mele, Andrea; Punta, Carlo; Melone, Lucio; Castiglione, Franca; Rossi, Barbara; Ferro, Monica; Crupi, Vincenza; Majolino, Domenico; Venuti, Valentina

    2014-01-01

    Summary A new hyper-branched water-soluble polymer was synthesized by reacting β-cyclodextrin with pyromellitic dianhydride beyond the critical conditions that allow the phenomenon of gelation to occur. The molar ratio between the monomers is a crucial parameter that rules the gelation process. Nevertheless, the concentration of monomers in the solvent phase plays a key role as well. Hyper-branched β-cyclodextrin-based polymers were obtained performing the syntheses with excess of solvent and cross-linking agent, and the conditions for critical dilution were determined experimentally. A hyper-branched polymer with very high water solubility was obtained and fully characterized both as for its chemical structure and for its capability to encapsulate substances. Fluorescein was used as probe molecule to test the complexation properties of the new material. PMID:25550720

  18. Preparation and characterization of novel molecularly imprinted polymers based on thiourea receptors for nitrocompounds recognition.

    PubMed

    Athikomrattanakul, Umporn; Katterle, Martin; Gajovic-Eichelmann, Nenad; Scheller, Frieder W

    2011-04-15

    Molecularly imprinted polymers (MIPs) for the recognition of nitro derivatives are prepared from three different (thio)urea-bearing functional monomers. The binding capability of the polymers is characterized by a batch binding experiment. The imprinting factors and affinity constants (K) of the imprinted polymers exhibit the same tendency as the binding constants (K(a)) of the functional monomers to the target substance in solution. Not only nitrofurantoin is efficiently bound by these MIPs but also a broad spectrum of other nitro compounds is bound with at the intermediate level, addressing that these (thio)urea-based monomers can be utilized to prepare a family of MIPs for various nitro compounds, which can be applied as recognition elements in separation and analytical application.

  19. Crossover time in relative fluctuations characterizes the longest relaxation time of entangled polymers

    NASA Astrophysics Data System (ADS)

    Uneyama, Takashi; Akimoto, Takuma; Miyaguchi, Tomoshige

    2012-09-01

    In entangled polymer systems, there are several characteristic time scales, such as the entanglement time and the disengagement time. In molecular simulations, the longest relaxation time (the disengagement time) can be determined by the mean square displacement (MSD) of a segment or by the shear relaxation modulus. Here, we propose the relative fluctuation analysis method, which is originally developed for characterizing large fluctuations, to determine the longest relaxation time from the center of mass trajectories of polymer chains (the time-averaged MSDs). Applying the method to simulation data of entangled polymers (by the slip-spring model and the simple reptation model), we provide a clear evidence that the longest relaxation time is estimated as the crossover time in the relative fluctuations.

  20. Polymers containing nickel(II) complexes of Goedken's macrocycle: optimized synthesis and electrochemical characterization.

    PubMed

    Paquette, Joseph A; Sauvé, Ethan R; Gilroy, Joe B

    2015-04-01

    The synthesis and characterization of a new class of nickel-containing polymers is described. The optimized copolymerization of alkyne-bearing nickel(II) complexes of Goedken's macrocycle (4,11-dihydro-5,7,12,14-tetramethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine) and brominated 9,9-dihexylfluorene produced polymers with potential application as functional redox-active materials. The title polymers exhibit electrochemically reversible, ligand-centered oxidation events at 0.24 and 0.73 V versus the ferrocene/ferrocenium redox couple. They also display exceptional thermal stability and interesting absorption properties due to the presence of the macrocyclic nickel(II) complexes and π-conjugated units incorporated in their backbones.

  1. Fabrication and characterization of submicron polymer waveguides by micro-transfer molding

    SciTech Connect

    Wu, Te-Wei

    2009-01-01

    Various methods exist for fabrication of micron and submicron sized waveguide structures. However, most of them include expensive and time consuming semiconductor fabrication techniques. An economical method for fabricating waveguide structures is introduced and demonstrated in this thesis. This method is established based on previously well-developed photonic crystal fabrication method called two-polymer microtransfer molding. The waveguide in this work functions by a coupler structure that diffracts the incident light into submicron polymer rods. The light is then guided through the rods. Characterization is done by collecting the light that has been guided through the waveguide and exits the end of these submicron polymer bars. The coupling and waveguiding capabilities are demonstrated using two light sources, a laser and white light.

  2. Development and Characterization of Healable Carbon Fiber Composites with a Reversibly Cross Linked Polymer

    SciTech Connect

    Ghezzo, Fabrizia; Smith, David R.; Starr, Tatiana N.; Perram, Timothy; Starr, Anthony F.; Darlington, Thomas K.; Baldwin, Richard K.; Oldenburg, Steven J.

    2010-10-18

    Carbon fiber reinforced polymer (CFRP) laminates with remendable cross-linked polymeric matrices were fabricated using a modified resin transfer mold (RTM) technique. The healable composite resin, bis-maleimide tetrafuran (2MEP4F), was synthesized by mixing two monomers, furan (4F) and maleimide (2MEP), at elevated temperatures. The fast kinetic rate of the reaction of polymer constituents requires a fast injection of the healable resin into the carbon fiber preform. The polymer viscosity as a function of time and temperature was experimentally quantified in order to optimize the fabrication of the composite material and to guarantee a uniform flow of the resin through the reinforcement. The method was validated by characterizing the thermo-mechanical properties of the polymerized 2MEP4F. Additionally, the thermo-mechanical properties of the remendable CFRP material were studied.

  3. Novel metal-organic photocatalysts: synthesis, characterization and decomposition of organic dyes.

    PubMed

    Gopal Reddy, N B; Murali Krishna, P; Kottam, Nagaraju

    2015-02-25

    An efficient method for the photocatalytic degradation of methylene blue in an aqueous medium was developed using metal-organic complexes. Two novel complexes were synthesized using, Schiff base ligand, N'-[(E)-(4-ethylphenyl)methylidene]-4-hydroxybenzohydrazide (HL) and Ni(II) (Complex 1)/Co(II) (Complex 2) chloride respectively. These complexes were characterized using microanalysis, various spectral techniques. Spectral studies reveal that the complexes exhibit square planar geometry with ligand coordination through azomethine nitrogen and enolic oxygen. The effects of catalyst dosage, irradiation time and aqueous pH on the photocatalytic activity were studied systematically. The photocatalytic activity was found to be more efficient in the presence of Ni(II) complexes than the Co(II) complex. Possible mechanistic aspects were discussed.

  4. Physiochemical characterization and antimicrobial evaluation of phenylthiourea-formaldehyde polymer (PTF) based polymeric ligand and its polymer metal complexes.

    PubMed

    Ahamad, Tansir; Alshehri, Saad M

    2013-05-01

    Phenylthiourea-formaldehyde polymer (PTF) has been synthesized via polycondensation of phenylthiourea and formaldehyde in basic medium and its corresponding metal complexes [PTF-M(II)] were prepared with Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) ions. The synthesized polymers have been characterized by elemental analysis, magnetic susceptibility, UV-visible, FT-IR, (1)H NMR, (13)C NMR, ESR spectroscopy and thermogravimetric analysis (TGA). Elemental analysis, electronic spectra and magnetic moment measurement indicate that PTF-Mn(II), PTF-Co(II) and PTF-Ni(II) show octahedral geometry, while PTF-Cu(II) and PTF-Zn(II) show square planar and tetrahedral geometry, respectively. The results of TGA ascribed that all the PTF-M(II) showed better heat-resistance properties than PTF resin. In vitro antimicrobial activities were performed against several bacteria and fungi using agar well diffusion method. The results of microbial activity were compared with Kanamycin and Miconazole as standard antibiotics for antibacterial and antifungal activities respectively.

  5. Physiochemical characterization and antimicrobial evaluation of phenylthiourea-formaldehyde polymer (PTF) based polymeric ligand and its polymer metal complexes

    NASA Astrophysics Data System (ADS)

    Ahamad, Tansir; Alshehri, Saad M.

    2013-05-01

    Phenylthiourea-formaldehyde polymer (PTF) has been synthesized via polycondensation of phenylthiourea and formaldehyde in basic medium and its corresponding metal complexes [PTF-M(II)] were prepared with Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) ions. The synthesized polymers have been characterized by elemental analysis, magnetic susceptibility, UV-visible, FT-IR, 1H NMR, 13C NMR, ESR spectroscopy and thermogravimetric analysis (TGA). Elemental analysis, electronic spectra and magnetic moment measurement indicate that PTF-Mn(II), PTF-Co(II) and PTF-Ni(II) show octahedral geometry, while PTF-Cu(II) and PTF-Zn(II) show square planar and tetrahedral geometry, respectively. The results of TGA ascribed that all the PTF-M(II) showed better heat-resistance properties than PTF resin. In vitro antimicrobial activities were performed against several bacteria and fungi using agar well diffusion method. The results of microbial activity were compared with Kanamycin and Miconazole as standard antibiotics for antibacterial and antifungal activities respectively.

  6. Synthesis and characterization of a novel polymer-ceramic system for biodegradable composite applications.

    PubMed

    Yang, Liu; Wang, Jian; Hong, Jason; Santerre, J Paul; Pilliar, Robert M

    2003-09-01

    The objective of this study was to develop a biodegradable polymer resin that could be used for the fabrication of an interpenetrating phase composite (IPC) made of porous calcium polyphosphate (CPP) and an organic polymer resin. The resin was synthesized from a polycarbonate-based divinyl oligomer and monomers containing ionic groups. The physical and chemical properties of the polymer resin and polycarbonate-based divinyl oligomer were characterized by gel permeation chromatography, Fourier transform infrared spectroscopy, and swelling studies. The in vitro degradation of the polymer resins was assessed using cholesterol esterase in a buffer solution at 37 degrees C for 3 weeks. Scanning electron microscopy of the degraded samples indicated that the hydrolysis of the resin was catalyzed by the enzyme. The relative interfacial shear strength between the polymer resin and the CPP ceramic was studied using a microbond test. The addition of ionic groups into the polymer resin chains appeared to improve the chemical bonding between the polymer and the CPP. Preliminary mechanical properties of the IPC were investigated by determining bending strength using a three point bending test. The data showed a sevenfold increase in strength over that of the monolithic CPP, and the addition of more ionic groups into the resin led to a higher bending strength for the newly formed CPP/polycarbonate resin system. Sample cross sections of the IPC examined using scanning electron microscopy suggested that the resin had infiltrated almost all of the pores of the CPP. The results of this study indicate that the IPC could potentially be used for fabricating novel biodegradable load-bearing implants.

  7. Synthesis and characterization of novel antibacterial polymers and clay delivery systems and polymeric phase transfer catalysts

    NASA Astrophysics Data System (ADS)

    Dizman, Bekir

    The research presented in this dissertation involves the syntheses of both novel antibacterial polymers and nanocomposites and polymeric phase transfer catalysts. The first section describes the synthesis, characterization, and antibacterial activities of new acrylate/methacrylate and acrylamide/methacrylamide polymers containing pendant quaternary ammonium compounds and norfloxacin. The first part of this section focuses on the syntheses and antibacterial activities of new water-soluble bis-quaternary ammonium methacrylate monomers and polymers (Chapter II). The monomers and polymers showed antibacterial activities against Staphylococcus aureus and Escherichia coli and the activity increased as the alkyl chain length in ammonium groups increased from 4 to 6 carbons. The results are very encouraging since polymers with quaternary ammonium compounds containing short alkyl chains are generally not active against bacteria. The second part of the first section involves the syntheses and antibacterial activities of various new monomers and polymers with amine and mono-quaternary ammonium groups on the side chain (Chapter III). The monomers were either the derivatives of 3-(acryloyloxy)-2-hydroxypropyl methacrylate (AHM) or based on acrylamide and methacrylamide derivatives. All monomers were homopolymerized and copolymerized with 2-hydroxyethylmethacrylate (HEMA). Amine monomers, their homopolymers and copolymers did not show any antibacterial activity against S. aureus and E. coli while the quaternized AHM-3-(aminomethyl) pyridine monomer, its homopolymer and copolymer with HEMA showed antibacterial activities against both bacteria. It was also found that the antibacterial activity of the quaternized methacrylamide-3-(aminomethyl) pyridine monomers and polymers increased as the alkyl chain length in ammonium groups increased. (Abstract shortened by UMI.)

  8. Core/shell CdS/ZnS nanoparticles: Molecular modelling and characterization by photocatalytic decomposition of Methylene Blue

    NASA Astrophysics Data System (ADS)

    Praus, Petr; Svoboda, Ladislav; Tokarský, Jonáš; Hospodková, Alice; Klemm, Volker

    2014-02-01

    Core/shell CdS/ZnS nanoparticles were modelled in the Material Studio environment and synthesized by one-pot procedure. The core CdS radius size and thickness of the ZnS shell composed of 1-3 ZnS monolayers were predicted from the molecular models. From UV-vis absorption spectra of the CdS/ZnS colloid dispersions transition energies of CdS and ZnS nanostructures were calculated. They indicated penetration of electrons and holes from the CdS core into the ZnS shell and relaxation strain in the ZnS shell structure. The transitions energies were used for calculation of the CdS core radius by the Schrödinger equation. Both the relaxation strain in ZnS shells and the size of the CdS core radius were predicted by the molecular modelling. The ZnS shell thickness and a degree of the CdS core coverage were characterized by the photocatalytic decomposition of Methylene Blue (MB) using CdS/ZnS nanoparticles as photocatalysts. The observed kinetic constants of the MB photodecomposition (kobs) were evaluated and a relationship between kobs and the ZnS shell thickness was derived. Regression results revealed that 86% of the CdS core surface was covered with ZnS and the average thickness of ZnS shell was about 12% higher than that predicted by molecular modelling.

  9. Synthesis and characterization of alkaline polyvinyl alcohol and poly(epichlorohydrin) blend polymer electrolytes and performance in electrochemical cells

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Chen; Lin, Sheng-Jen; Hsu, Sung-Ting

    Alkaline SPE was obtained from a blend of polyvinyl alcohol (PVA) and poly(epichlorohydrin) (PECH), PVA-PECH, by a solution-cast technique. The PVA host polymer is blended with PECH polymer to provide a polymer electrolyte with improved chemical and mechanical properties. The ionic conductivity of the PVA-PECH polymer electrolytes is between 10 -2 and 10 -3 S cm -1 at room temperature when the blend ratio is varied from 1:0.2 to 1:1. The PVA-PECH polymer was characterized by means of scanning electron microscopy, X-ray diffraction, stress-strain test, cyclic voltammetry, and a.c. impedance spectroscopy. It is found that the polymer electrolytes exhibit good mechanical strength and excellent chemical stability. The electrochemical performance of solid-state Zn-air batteries with various types of the blended polymer electrolyte films is examined by a galvanostatic discharge method.

  10. Elastic and viscoelastic characterization of inhomogeneous polymers by bimodal atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Nguyen, Hung K.; Ito, Makiko; Nakajima, Ken

    2016-08-01

    The elastic and viscoelastic responses of inhomogeneous polymers upon interacting with an atomic force microscopy (AFM) probe are simultaneously characterized by a bimodal AFM approach namely the amplitude- and frequency-modulation (AM-FM) method. In this approach, the AFM probe is operated in the AM mode at the first flexural frequency and in the FM mode at a higher flexural frequency. The AM mode provides information about the viscoelasticity of polymers in terms of the mechanical loss tangent, whereas the modulus of polymers is obtained as a function of the frequency shift of flexural frequencies in both modes. For a glassy polymer blend, the AM-FM method provides a consistent result in both the elastic modulus and loss tangent in comparison with those obtained by other methods. Moreover, a significant improvement of the contrast and lateral resolution in the AM-FM modulus image can be observed. However, the current approach shows a substantial increase in the modulus of rubbery polymers.

  11. Synthesis, characterization, and transistor and solar cell applications of a naphthobisthiadiazole-based semiconducting polymer.

    PubMed

    Osaka, Itaru; Shimawaki, Masafumi; Mori, Hiroki; Doi, Iori; Miyazaki, Eigo; Koganezawa, Tomoyuki; Takimiya, Kazuo

    2012-02-22

    We report the synthesis and characterization of a novel donor-acceptor semiconducting polymer bearing naphthobisthiadiazole (NTz), a doubly benzothiadiazole (BTz)-fused ring, and its applications to organic field-effect transistors and bulk heterojunction solar cells. With NTz's highly π-extended structure and strong electron affinity, the NTz-based polymer (PNTz4T) affords a smaller bandgap and a deeper HOMO level than the BTz-based polymer (PBTz4T). PNTz4T exhibits not only high field-effect mobilities of ~0.56 cm(2)/(V s) but also high photovoltaic properties with power conversion efficiencies of ~6.3%, both of which are significantly high compared to those for PBTz4T. This is most likely due to the more suitable electronic properties and, importantly, the more highly ordered structure of PNTz4T in the thin film than that of PBTz4T, which might originate in the different symmetry between the cores. NTz, with centrosymmetry, can lead to a more linear backbone in the present polymer system than BTz with axisymmetry, which might be favorable for better molecular ordering. These results demonstrate great promise for using NTz as a bulding unit for high-performance semiconducting polymers for both transistors and solar cells.

  12. Stainless steel grafting of hyperbranched polymer brushes with an antibacterial activity: synthesis, characterization, and properties.

    PubMed

    Ignatova, Milena; Voccia, Samule; Gabriel, Sabine; Gilbert, Bernard; Cossement, Damien; Jerome, Robert; Jerome, Christine

    2009-01-20

    Two strategies were used for the preparation of hyperbranched polymer brushes with a high density of functional groups: (a) the cathodic electrografting of stainless steel by poly[2-(2-chloropropionate)ethyl acrylate] [poly(cPEA)], which was used as a macroinitiator for the atom transfer radical polymerization of an inimer, 2-(2-bromopropionate)ethyl acrylate in the presence or absence of heptadecafluorodecyl acrylate, (b) the grafting of preformed hyperbranched poly(ethyleneimine) onto poly(N-succinimidyl acrylate) previously electrografted onto stainless steel. The hyperbranched polymer, which contained either bromides or amines, was quaternized because the accordingly formed quaternary ammonium or pyridinium groups are known for antibacterial properties. The structure, chemical composition, and morphology of the quaternized and nonquaternized hyperbranched polymer brushes were characterized by ATR-FTIR reflectance, Raman spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. The peeling test confirmed that the grafted hyperbranched polymer films adhered much more strongly to stainless steel than the nongrafted solvent-cast films. The quaternized hyperbranched polymer brushes were more effective in preventing both protein adsorption and bacterial adhesion than quaternary ammonium containing poly(cPEA) primary films, more likely because of the higher hydrophilicity and density of cationic groups.

  13. Preparation and characterization of erythromycin molecularly imprinted polymers based on distillation-precipitation polymerization.

    PubMed

    Liu, Jiang; Li, Le; Tang, Hui; Zhao, Feilang; Ye, Bang-Ce; Li, Yingchun; Yao, Jun

    2015-09-01

    Erythromycin-imprinted polymers with excellent recognition properties were prepared by an innovative strategy called distillation-precipitation polymerization. The interaction between erythromycin and methacrylic acid was studied by ultraviolet absorption spectroscopy, and the as-prepared materials were characterized by Fourier-transform infrared spectroscopy and scanning electron microscopy. Moreover, their binding performances were evaluated in detail by static, kinetic and selective sorption tests. It was found that the molecularly imprinted polymers afforded good morphology, monodispersity, and high adsorption capacity when the fraction of the monomers was 7 vol% in the whole reaction system, and the adsorption data for imprinted polymers correlated well with the Langmuir model. The maximum capacity of the imprinted and the non-imprinted polymers for adsorbing erythromycin is 44.03 and 19.95 mg/g, respectively. The kinetic studies revealed that the adsorption process fitted a pseudo-second-order kinetic model. Furthermore, the imprinted polymers display higher affinity toward erythromycin, compared with its analogue roxithromycin.

  14. Synthesis, characterization, and biocide properties of semicarbazide-formaldehyde resin and its polymer metal complexes.

    PubMed

    Nishat, Nahid; Ahamad, Tansir; Alshehri, Saad M; Parveen, Shadma

    2010-04-01

    Semicarbazide-formaldehyde resin (SFRs) was prepared by the condensation of semicarbazide with formaldehyde in an acidic medium and its polymer metal complexes were prepared with transition metal ions. All the synthesized polymers were characterized by elemental analysis, FTIR, (1)H NMR, (13)C NMR, electronic spectroscopy, magnetic moment measurement and thermogravimetric analyses. The percentage of metal in all the polymer metal complexes was found to be consistent with 2:1 (resin: metal) stoichiometry. The magnetic susceptibility measurement and electronic spectra of all the polymer metal complexes confirmed the geometry of the complexes. All the synthesized polymeric compounds have been screened in vitro against Bacillus subtilis, Staphylococcus aureus (Gram-positive) and Escherichia coli, Salmonella typhi (Gram-negative) using shaking flask method. The entire polymer metal complexes showed excellent anti-bacterial activity and low toxicity when compared with their parental polymeric resin. The anti-bacterial activity and toxicity of the entire synthesized compound is significant and they can be used as antimicrobial as well as anticancer agents for mammals in future.

  15. Characterization of selected LDEF: Exposed polymer films and resins

    NASA Technical Reports Server (NTRS)

    Young, Philip R.; Slemp, Wayne S.

    1992-01-01

    The Long Duration Exposure Facility (LDEF) provided a unique environmental exposure of a wide variety of materials. The effects of 5 years and 10 months of Low-Earth Orbit (LEO) exposure of these materials to atomic oxygen, ultraviolet and particulate radiation, meteoroid and debris, vacuum, contamination, and thermal cycling is providing a data base unparalleled in the history of space environment research. Working though the Environmental Effects on Materials Special Investigation Group (MSIG), a number of polymeric materials in various processed forms have been assembled from LDEF investigators for analysis at the NASA Langley Research Center. This paper reports the status of on-going chemical characterization of these materials.

  16. Fast Geostatistical Inversion using Randomized Matrix Decompositions and Sketchings for Heterogeneous Aquifer Characterization

    NASA Astrophysics Data System (ADS)

    O'Malley, D.; Le, E. B.; Vesselinov, V. V.

    2015-12-01

    We present a fast, scalable, and highly-implementable stochastic inverse method for characterization of aquifer heterogeneity. The method utilizes recent advances in randomized matrix algebra and exploits the structure of the Quasi-Linear Geostatistical Approach (QLGA), without requiring a structured grid like Fast-Fourier Transform (FFT) methods. The QLGA framework is a more stable version of Gauss-Newton iterates for a large number of unknown model parameters, but provides unbiased estimates. The methods are matrix-free and do not require derivatives or adjoints, and are thus ideal for complex models and black-box implementation. We also incorporate randomized least-square solvers and data-reduction methods, which speed up computation and simulate missing data points. The new inverse methodology is coded in Julia and implemented in the MADS computational framework (http://mads.lanl.gov). Julia is an advanced high-level scientific programing language that allows for efficient memory management and utilization of high-performance computational resources. Inversion results based on series of synthetic problems with steady-state and transient calibration data are presented.

  17. Development and Characterization of New Donor-Acceptor Conjugated Polymers and Fullerene Nanoparticles for High Performance Bulk Heterojunction Solar Cells

    DTIC Science & Technology

    2011-01-14

    Nanoparticles for High Performance Bulk Heterojunction Solar Cells Jan. 14,2011 Name of Principal Investigators: Kung-Hwa Wei - e-mail address : khwei...donor-π-bridge-acceptor side chains for high efficiency polymer solar cells . Different from the commonly used linear D-A conjugated polymers, the...Development and Characterization of New Donor-Acceptor Conjugated Polymers and Fullerene Nanoparticles for High Performance Bulk Heterojunction Solar Cells

  18. Characterization of interictal epileptiform discharges with time-resolved cortical current maps using the helmholtz-hodge decomposition.

    PubMed

    Slater, Jeremy D; Khan, Sheraz; Li, Zhimin; Castillo, Eduardo

    2012-01-01

    Source estimates performed using a single equivalent current dipole (ECD) model for interictal epileptiform discharges (IEDs) which appear unifocal have proven highly accurate in neocortical epilepsies, falling within millimeters of that demonstrated by electrocorticography. Despite this success, the single ECD solution is limited, best describing sources which are temporally stable. Adapted from the field of optics, optical flow analysis of distributed source models of MEG or EEG data has been proposed as a means to estimate the current motion field of cortical activity, or "cortical flow." The motion field so defined can be used to identify dynamic features of interest such as patterns of directional flow, current sources, and sinks. The Helmholtz-Hodge Decomposition (HHD) is a technique frequently applied in fluid dynamics to separate a flow pattern into three components: (1) a non-rotational scalar potential U describing sinks and sources, (2) a non-diverging scalar potential A accounting for vortices, and (3) an harmonic vector field H. As IEDs seem likely to represent periods of highly correlated directional flow of cortical currents, the U component of the HHD suggests itself as a way to characterize spikes in terms of current sources and sinks. In a series of patients with refractory epilepsy who were studied with magnetoencephalography as part of their evaluation for possible resective surgery, spike localization with ECD was compared to HHD applied to an optical flow analysis of the same spike. Reasonable anatomic correlation between the two techniques was seen in the majority of patients, suggesting that this method may offer an additional means of characterization of epileptic discharges.

  19. Preparation and characterization of PVC-LiClO 4 based composite polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Ahmad, A.; Rahman, M. Y. A.; Su'ait, M. S.

    2008-11-01

    The preparation of PVC-LiClO 4 based composite polymer electrolyte was carried out to study the effect of ceramic fillers such as ZnO, TiO 2 and Al 2O 3 on the room temperature conductivity. The samples were tested using impedance spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The samples were prepared with different percentage (%) by weight of ceramic filler. The highest ionic conductivity achieved was 3.7×10 -7 S cm -1 for the sample prepared with 20% of ZnO. The glass transition temperature decreases with the fillers concentration due to the increasing amorphous state. While, the decomposition temperature increases with the increase in the fillers content. Both of these thermal properties influence the enhancement of the conductivity value. The morphology of the samples shows the even distribution of the ceramic filler in the samples however the filler starts to agglomerate in the sample at higher concentration of filler. In conclusion, the addition of ceramic filler improves the ionic conductivity of PVC-LiCIO 4 composite polymer electrolyte.

  20. Characterization of electrophoretic suspension for thin polymer film deposition

    NASA Astrophysics Data System (ADS)

    Mladenova, D.; Weiter, M.; Stepanek, P.; Ouzzane, I.; Vala, M.; Sinigersky, V.; Zhivkov, I.

    2012-03-01

    The optical absorption and fluorescence spectra of poly [2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] toluene solutions and 50:50% toluene/acetonitrile suspensions show clearly distinguishable differences (e.g., peak broadening and shifting), which could be used for characterization of suspensions with different acetonitrile content. The dynamic light scattering (DLS) measurement of the suspensions prepared showed a particle size of 90 nm. Thin films with thicknesses of about 400 nm were prepared by electrophoretic deposition (EPD) and spin coating. As the films are very soft, a contactless optical profilometry techique based on chromatic aberration was used to measure their thickness. AFM imaging of spin coated and EPD films revealed film roughness of 20÷40 nm and 40÷80 nm, respectively. The EPD film roughness seems to be less than the suspension particle size obtained by DLS, probably due to the partial film dissolving by the toluene present in the suspension.

  1. Acoustical characterization of polysaccharide polymers tissue-mimicking materials.

    PubMed

    Cuccaro, Rugiada; Musacchio, Chiara; Giuliano Albo, P Alberto; Troia, Adriano; Lago, Simona

    2015-02-01

    Tissue-mimicking phantoms play a crucial role in medical ultrasound research because they can simulate biological soft tissues. In last years, many types of polymeric tissues have been proposed and characterized from an acoustical and a thermal point of view, but, rarely, a deep discussion about the quality of the measurements, in terms of the uncertainty evaluation, has been reported. In this work, considering the necessity to develop laboratory standards for the measurement of ultrasonic exposure and dose quantities, a detailed description of the experimental apparatuses for the sound speed and the attenuation coefficient measurements is given, focusing the attention on the uncertainty evaluation both of the results and analysis algorithms. In particular, this algorithm reveals a novel empirical relation, fixing a limit to the energy content (therefore limits the number of cycles) of the three parts in which the authors have proposed to divide the acoustical signal. Furthermore, the realisation of multi-components phantoms, Agar and Phytagel based tissue-mimicking gels along with others long chain molecules (dextrane or polyvinyl alcohol) and scattering materials (silicon carbide and kieselguhr) are investigated. This paper reports accurate speed of sound and attenuation coefficient measurements. Speed of sound is measured by a pulse-echo technique in far-field condition, using an optical glass buffer rod; while attenuation coefficient is determined by an insertion technique, using demineralized water as reference material. The experimental sound speed results are subjected to an overall estimated relative uncertainty of about 1.5% and the attenuation coefficient uncertainty is less than 2.5%. For the development of laboratory standards, a detailed analysis of the measurement uncertainty is fundamental to make sample properties comparable. The authors believe this study could represent the right direction to make phantoms characterizations referable and traceable.

  2. Characterization of ι-carrageenan and its derivative based green polymer electrolytes

    SciTech Connect

    Jumaah, Fatihah Najirah; Mobaraka, Nadhratun Naiim; Ahmad, Azizan; Ramli, Nazaruddin

    2013-11-27

    The new types of green polymer electrolytes based on ι-carrageenan derivative have been prepared. ι-carrageenan act as precursor was reacted with monochloroacetic acid to produce carboxymethyl ι-carrageenan. The powders were characterized by Attenuated Total Reflection Fourier Transform infrared (ATR-FTIR) spectroscopy and {sup 1}H nuclear magnetic resonance (NMR) to confirm the substitution of targeted functional group in ι-carrageenan. The green polymer electrolyte based on ι-carrageenan and carboxymethyl ι-carrageenan was prepared by solution-casting technique. The films were characterized by electrochemical impedance spectroscopy to determine the ionic conductivity. The ionic conductivity ι-carrageenan film were higher than carboxymethyl ι-carrageenan which 4.87 ×10{sup −6} S cm{sup −1} and 2.19 ×10{sup −8} S cm{sup −1}, respectively.

  3. Synthesis and characterization of metal-polymer nanocomposites with radiation-protective properties

    NASA Astrophysics Data System (ADS)

    Bychkov, A. N.; Dzhardimalieva, G. I.; Fetisov, G. P.; Valskiy, V. V.; Golubeva, N. D.; Pomogailo, A. D.

    2016-12-01

    Metal-polymer nanocomposites, which can weaken the activity of a beta radiation source in undesirable directions at the minimum protection size, are developed. These nanocomposites are fabricated by dispersing metal-containing nanoparticles in thermoplastic matrices. Metal nanoparticles are synthesized by the polymerassisted thermolysis of metal-containing precursors. The composition and structure of the nanocomposites are characterized by elemental and X-ray diffraction analyses and transmission electron microscopy.

  4. Synthesis and Characterization of Conducting Elastomers Based on Interpenetrated C60-Derived Polymer Networks

    DTIC Science & Technology

    2007-11-02

    CHARACTERIZATION OF CONDUCTING ELASTOMERS BASED ON INTERPENETRATED C 60-DERIVED POLYMER NETWORKS" 6. AUTHOR( S ) PROFESSOR LONG Y. CHIANG PROFESSOR LEE Y. WANG 7...PERFORMING ORGANIZATION NAME( S ) AND ADDRESS(ES) IHE FOUNDATION OF CONDENSED MATTER SCIENCES NATIONAL TAIWAN UNIVERSITY 1 ROOSEVELT ROAD TAIPEI...TAIWAN 9. SPONSORING/MONITORING AGENCY NAME( S ) AND ADDRESS(ES) ASIAN OFFICE OF AEROSPACE RESEARCH AND DEVELOPMENT (AOARD) UNIT 45002 f\\P0 AP 96337

  5. Synthesis and Characterization of Thin Film Lithium-Ion Batteries Using Polymer Electrolytes

    NASA Technical Reports Server (NTRS)

    Maranchi, Jeffrey P.; Kumta, Prashant N.; Hepp, Aloysius F.; Raffaelle, Ryne P.

    2002-01-01

    The present paper describes the integration of thin film electrodes with polymer electrolytes to form a complete thin film lithium-ion battery. Thin film batteries of the type, LiCoO2 [PAN, EC, PC, LiN(CF3SO2)2] SnO2 have been fabricated. The results of the synthesis and characterization studies will be presented and discussed.

  6. Characterizing electroactive polymers for use in robotic surgical instruments

    NASA Astrophysics Data System (ADS)

    Snyder, Alan J.; Cohen, Adam L.; Cheng, Zhong-Yang; Zhang, Qi Ming; Runt, James P.

    2002-07-01

    The popularity of minimally invasive surgical procedures over traditional open procedures motivates us to develop new instruments that address the limits of existing technology and enable more widespread use of minimally invasive approaches. Robotic surgical instruments have the potential to provide improved dexterity and range of motion within the confines of the human body when compared with manually actuated instruments. The high strain response and elastic energy density of electron-irradiated P(VDF-TrFE) make it a candidate actuator material for robotic instruments that provide electronic mediation and multiple degrees of freedom of tip movement. We are currently studying both active and passive properties of P(VDF-TrFE) with the goal of constructing a mathematical model of the material's behavior. Studies have been conducted on 15 micron thick film samples in rolled and rolled-flattened configurations. Passive properties can be represented by a 5 parameter viscoelastic model with two time constants on the order of ten and 200 seconds. Active responses were found to have strong dependence upon field and modest dependence upon load. We suggest means by which the active and passive responses can be combined in a model of steady-state response that would be of value in positioning tasks. The time course of the active response appears to contain components on two time scales, but further studies are required to characterized it in more detail.

  7. Characterization of ultraviolet-photocured acrylamide based polymer

    NASA Astrophysics Data System (ADS)

    Rozi, Normazida; Hanifah, Sharina Abu; Heng, Lee Yook; Shyuan, Loh Kee

    2016-11-01

    Poly (acrylamide-co-ethyl methacrylate) (AAm-co-EMA) membrane was studied and compared with poly (acrylamide) (AAm). Poly (AAm-co-EMA) and poly (AAm) membranes were synthesized using photopolymerization technique. These membranes were characterized by Fourier Transform Infrared (FTIR), swelling test and scanning electron microscopy (SEM). The aim of this study was to investigate the suitability of these membranes to be used for enzyme immobilization. FTIR spectra exhibited peaks of -CO and -CH3 functional groups at 1166 cm-1 and 1377 cm-1 and confirmed that poly (AAm-co-EMA) was successfully formed. The equilibrium swelling percentage of poly (AAm) and poly (AAm-co-EMA) were 93.97 % and 96.24 %. It was found out that 10 % of EMA monomer was added to form the copolymer, the membrane produced a good hydrolytic stability copolymer in water and indicated its biocompatibility. This finding may be attributed by the morphology property as a semi porous surface of copolymer was formed. In conclusion, poly (AAM-co-EMA) was successfully synthesized and more suitable for enzyme immobilization.

  8. Additive Manufacturing and Characterization of Ultem Polymers and Composites

    NASA Technical Reports Server (NTRS)

    Chuang, Kathy C.; Grady, Joseph E.; Draper, Robert D.; Shin, Euy-Sik E.; Patterson, Clark; Santelle, Thomas D.

    2015-01-01

    The objective of this project was to conduct additive manufacturing to produce aircraft engine components by Fused Deposition Modeling (FDM), using commercially available polyetherimides - Ultem 9085 and experimental Ultem 1000 mixed with 10 percent chopped carbon fiber. A property comparison between FDM-printed and injection-molded coupons for Ultem 9085, Ultem 1000 resin and the fiber-filled composite Ultem 1000 was carried out. Furthermore, an acoustic liner was printed from Ultem 9085 simulating conventional honeycomb structured liners and tested in a wind tunnel. Composite compressor inlet guide vanes were also printed using fiber-filled Ultem 1000 filaments and tested in a cascade rig. The fiber-filled Ultem 1000 filaments and composite vanes were characterized by scanning electron microscope (SEM) and acid digestion to determine the porosity of FDM-printed articles which ranged from 25-31 percent. Coupons of Ultem 9085 and experimental Ultem 1000 composites were tested at room temperature and 400 degrees Fahrenheit to evaluate their corresponding mechanical properties.

  9. Characterization of the Binding Properties of Molecularly Imprinted Polymers.

    PubMed

    Ansell, Richard J

    2015-01-01

    The defining characteristic of the binding sites of any particular molecularly imprinted material is heterogeneity: that is, they are not all identical. Nonetheless, it is useful to study their fundamental binding properties, and to obtain average properties. In particular, it has been instructive to compare the binding properties of imprinted and non-imprinted materials. This chapter begins by considering the origins of this site heterogeneity. Next, the properties of interest of imprinted binding sites are described in brief: affinity, selectivity, and kinetics. The binding/adsorption isotherm, the graph of concentration of analyte bound to a MIP versus concentration of free analyte at equilibrium, over a range of total concentrations, is described in some detail. Following this, the techniques for studying the imprinted sites are described (batch-binding assays, radioligand binding assays, zonal chromatography, frontal chromatography, calorimetry, and others). Thereafter, the parameters that influence affinity, selectivity and kinetics are discussed (solvent, modifiers of organic solvents, pH of aqueous solvents, temperature). Finally, mathematical attempts to fit the adsorption isotherms for imprinted materials, so as to obtain information about the range of binding affinities characterizing the imprinted sites, are summarized.

  10. Synthesis and characterization of benzodithiophene and benzotriazole-based polymers for photovoltaic applications.

    PubMed

    Gedefaw, Desta; Tessarolo, Marta; Bolognesi, Margherita; Prosa, Mario; Kroon, Renee; Zhuang, Wenliu; Henriksson, Patrik; Bini, Kim; Wang, Ergang; Muccini, Michele; Seri, Mirko; Andersson, Mats R

    2016-01-01

    Two high bandgap benzodithiophene-benzotriazole-based polymers were synthesized via palladium-catalysed Stille coupling reaction. In order to compare the effect of the side chains on the opto-electronic and photovoltaic properties of the resulting polymers, the benzodithiophene monomers were substituted with either octylthienyl (PTzBDT-1) or dihexylthienyl (PTzBDT-2) as side groups, while the benzotriazole unit was maintained unaltered. The optical characterization, both in solution and thin-film, indicated that PTzBDT-1 has a red-shifted optical absorption compared to PTzBDT-2, likely due to a more planar conformation of the polymer backbone promoted by the lower content of alkyl side chains. The different aggregation in the solid state also affects the energetic properties of the polymers, resulting in a lower highest occupied molecular orbital (HOMO) for PTzBDT-1 with respect to PTzBDT-2. However, an unexpected behaviour is observed when the two polymers are used as a donor material, in combination with PC61BM as acceptor, in bulk heterojunction solar cells. Even though PTzBDT-1 showed favourable optical and electrochemical properties, the devices based on this polymer present a power conversion efficiency of 3.3%, considerably lower than the efficiency of 4.7% obtained for the analogous solar cells based on PTzBDT-2. The lower performance is presumably attributed to the limited solubility of the PTzBDT-1 in organic solvents resulting in enhanced aggregation and poor intermixing with the acceptor material in the active layer.

  11. Synthesis and characterization of benzodithiophene and benzotriazole-based polymers for photovoltaic applications

    PubMed Central

    Gedefaw, Desta; Tessarolo, Marta; Bolognesi, Margherita; Prosa, Mario; Kroon, Renee; Zhuang, Wenliu; Henriksson, Patrik; Bini, Kim; Wang, Ergang; Muccini, Michele

    2016-01-01

    Summary Two high bandgap benzodithiophene–benzotriazole-based polymers were synthesized via palladium-catalysed Stille coupling reaction. In order to compare the effect of the side chains on the opto-electronic and photovoltaic properties of the resulting polymers, the benzodithiophene monomers were substituted with either octylthienyl (PTzBDT-1) or dihexylthienyl (PTzBDT-2) as side groups, while the benzotriazole unit was maintained unaltered. The optical characterization, both in solution and thin-film, indicated that PTzBDT-1 has a red-shifted optical absorption compared to PTzBDT-2, likely due to a more planar conformation of the polymer backbone promoted by the lower content of alkyl side chains. The different aggregation in the solid state also affects the energetic properties of the polymers, resulting in a lower highest occupied molecular orbital (HOMO) for PTzBDT-1 with respect to PTzBDT-2. However, an unexpected behaviour is observed when the two polymers are used as a donor material, in combination with PC61BM as acceptor, in bulk heterojunction solar cells. Even though PTzBDT-1 showed favourable optical and electrochemical properties, the devices based on this polymer present a power conversion efficiency of 3.3%, considerably lower than the efficiency of 4.7% obtained for the analogous solar cells based on PTzBDT-2. The lower performance is presumably attributed to the limited solubility of the PTzBDT-1 in organic solvents resulting in enhanced aggregation and poor intermixing with the acceptor material in the active layer. PMID:27559416

  12. Electrochemical characterization of electrospun nanocomposite polymer blend electrolyte fibrous membrane for lithium battery.

    PubMed

    Padmaraj, O; Rao, B Nageswara; Venkateswarlu, M; Satyanarayana, N

    2015-04-23

    Novel hybrid (organic/inorganic) electrospun nanocomposite polymer blend electrolyte fibrous membranes with the composition poly(vinylidene difluoride-co-hexafluoropropylene) [P(VdF-co-HFP)]/poly(methyl methacrylate) [P(MMA)]/magnesium aluminate (MgAl2O4)/LiPF6 were prepared by the electrospinning technique. All of the prepared electrospun P(VdF-co-HFP), PMMA blend [90% P(VdF-co-HFP)/10% PMMA], and nanocomposite polymer blend [90% P(VdF-co-HFP)/10% PMMA/x wt % MgAl2O4 (x = 2, 4, 6, and 8)] fibrous membranes were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. The fibrous nanocomposite separator-cum-polymer blend electrolyte membranes were obtained by soaking the nanocomposite polymer blend membranes in an electrolyte solution containing 1 M LiPF6 in ethylene carbonate (EC)/diethyl carbonate (DEC) (1:1, v/v). The newly developed fibrous nanocomposite polymer blend electrolyte [90% P(VdF-co-HFP)/10% PMMA/6 wt % MgAl2O4/LiPF6] membrane showed a low crystallinity, low average fiber diameter, high thermal stability, high electrolyte uptake, high conductivity (2.60 × 10(-3) S cm(-1)) at room temperature, and good potential stability above 4.5 V. The best properties of the fibrous nanocomposite polymer blend electrolyte (NCPBE) membrane with a 6 wt % MgAl2O4 filler content was used for the fabrication of a Li/NCPBE/LiCoO2 CR 2032 coin cell. The electrochemical performance of the fabricated CR 2032 cell was evaluated at a current density of 0.1 C-rate. The fabricated CR 2032 cell lithium battery using the newly developed NCPBE membrane delivered an initial discharge capacity of 166 mAh g(-1) and a stable cycle performance.

  13. Short wave infrared hyperspectral imaging for recovered post-consumer single and mixed polymers characterization

    NASA Astrophysics Data System (ADS)

    Bonifazi, Giuseppe; Palmieri, Roberta; Serranti, Silvia

    2015-03-01

    Postconsumer plastics from packing and packaging represent about the 60% of the total plastic wastes (i.e. 23 million of tons) produced in Europe. The EU Directive (2014/12/EC) fixes as target that the 60%, by weight, of packaging waste has to be recovered, or thermally valorized. When recovered, the same directive established that packaging waste has to be recycled in a percentage ranging between 55% (minimum) and 60% (maximum). The non-respect of these rules can produce that large quantities of end-of-life plastic products, specifically those utilized for packaging, are disposed-off, with a strong environmental impact. The application of recycling strategies, finalized to polymer recovery, can represent an opportunity to reduce: i) not renewable raw materials (i.e. oil) utilization, ii) carbon dioxide emissions and iii) amount of plastic waste disposed-off. Aim of this work was to perform a full characterization of different end-of-life polymers based products, constituted not only by single polymers but also of mixtures, in order to realize their identification for quality control and/or certification assessment. The study was specifically addressed to characterize the different recovered products as resulting from a recycling plant where classical processing flow-sheets, based on milling, classification and separation, are applied. To reach this goal, an innovative sensing technique, based on the utilization of a HyperSpectral[b] I[/b]maging (HSI) device working in the SWIR region (1000-2500 nm), was investigated. Following this strategy, single polymers and/or mixed polymers recovered were correctly recognized. The main advantage of the proposed approach is linked to the possibility to perform "on-line" analyses, that is directly on the different material flow streams, as resulting from processing, without any physical sampling and classical laboratory "off-line" determination.

  14. Conjugation of Polymer-Coated Gold Nanoparticles with Antibodies—Synthesis and Characterization

    PubMed Central

    Tan, Gamze; Kantner, Karsten; Zhang, Qian; Soliman, Mahmoud G.; del Pino, Pablo; Parak, Wolfgang J.; Onur, Mehmet A.; Valdeperez, Daniel; Rejman, Joanna; Pelaz, Beatriz

    2015-01-01

    The synthesis of polymer-coated gold nanoparticles with high colloidal stability is described, together with appropriate characterization techniques concerning the colloidal properties of the nanoparticles. Antibodies against vascular endothelial growth factor (VEGF) are conjugated to the surface of the nanoparticles. Antibody attachment is probed by different techniques, giving a guideline about the characterization of such conjugates. The effect of the nanoparticles on human adenocarcinoma alveolar basal epithelial cells (A549) and human umbilical vein endothelial cells (HUVECs) is probed in terms of internalization and viability assays. PMID:28347065

  15. [Synthesis and Characterization of a Sugar Based Electrolyte for Thin-film Polymer Batteries

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The work performed during the current renewal period, March 1,1998 focused primarily on the synthesis and characterization of a sugar based electrolyte for thin-film polymer batteries. The initial phase of the project involved developing a suitable sugar to use as the monomer in the polymeric electrolyte synthesis. The monomer has been synthesized and characterized completely. Overall the yield of this material is high and it can be produced in relatively large quantity easily and in high purity. The scheme used for the preparation of the monomer is outlined along with pertinent yields.

  16. Polymer Brushes Containing Sulfonated Sugar Repeat Units: Synthesis, Characterization and In Vitro Testing of Blood Coagulation Activation

    PubMed Central

    Ayres, N.; Holt, D. J.; Jones, C.F.; Corum, L. E.; Grainger, D. W.

    2009-01-01

    A new polymer brush chemistry containing sulfonated carbohydrate repeat units has been synthesized from silicon substrates using ATRP methods and characterized both in bulk and using surface analysis. The polymer brush was designed to act as a mimic for the naturally occurring sulfonated glycosaminoglycan, heparin, commonly used for modifying blood-contacting surfaces both in vitro and in vivo. Surface analysis showed conversion of brush saccharide precursor chemistry to the desired sulfonated polymer product. The sulfonated polymer brush surface was further analyzed using three conventional in vitro tests for blood compatibility -- plasma recalcification times, complement activation, and thrombin generation. The sulfonated polymer brush films on silicon oxide wafers exhibited better assay performance in these blood component assays than the unsulfonated sugar functionalized polymer brush in all tests performed. PMID:19859552

  17. Characterization of Homopolymer and Polymer Blend Films by Phase Sensitive Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Ngwa, Wilfred; Wannemacher, Reinhold; Grill, Wolfgang

    2003-03-01

    CHARACTERIZATION OF HOMOPOLYMER AND POLYMER BLEND FILMS BY PHASE SENSITIVE ACOUSTIC MICROSCOPY W Ngwa, R Wannemacher, W Grill Institute of Experimental Physics II, University of Leipzig, 04103 Leipzig, Germany Abstract We have used phase sensitive acoustic microscopy (PSAM) to study homopolymer thin films of polystyrene (PS) and poly (methyl methacrylate) (PMMA), as well as PS/PMMA blend films. We show from our results that PSAM can be used as a complementary and highly valuable technique for elucidating the three-dimensional (3D) morphology and micromechanical properties of thin films. Three-dimensional image acquisition with vector contrast provides the basis for: complex V(z) analysis (per image pixel), 3D image processing, height profiling, and subsurface image analysis of the polymer films. Results show good agreement with previous studies. In addition, important new information on the three dimensional structure and properties of polymer films is obtained. Homopolymer film structure analysis reveals (pseudo-) dewetting by retraction of droplets, resulting in a morphology that can serve as a starting point for the analysis of polymer blend thin films. The outcome of confocal laser scanning microscopy studies, performed on the same samples are correlated with the obtained results. Advantages and limitations of PSAM are discussed.

  18. Analytical characterization of polymers used in conservation and restoration by ATR-FTIR spectroscopy.

    PubMed

    Chércoles Asensio, Ruth; San Andrés Moya, Margarita; de la Roja, José Manuel; Gómez, Marisa

    2009-12-01

    In the last few decades many new polymers have been synthesized that are now being used in cultural heritage conservation. The physical and chemical properties and the long-term behaviors of these new polymers are determined by the chemical composition of the starting materials used in their synthesis along with the nature of the substances added to facilitate their production. The practical applications of these polymers depend on their composition and form (foam, film, sheets, pressure-sensitive adhesives, heat-seal adhesives, etc.). Some materials are used in restoration works and others for the exhibition, storage and transport of works of art. In all cases, it is absolutely necessary to know their compositions. Furthermore, many different materials that are manufactured for other objectives are also used for conservation and restoration. The technical information about the materials provided by the manufacturer is usually incomplete, so it is necessary to analytically characterize such materials. FTIR spectrometry is widely used for polymer identification, and, more recently, ATR-FTIR has been shown to give excellent results. This paper reports the ATR-FTIR analysis of samples of polymeric materials used in the conservation of artworks. These samples were examined directly in the solid material without sample preparation.

  19. Synthesis, characterization and properties of novel blue light emitting discrete π-functional polymer consisting of carbazole and anthracene units and their applications in polymer light emitting diodes

    NASA Astrophysics Data System (ADS)

    Gopal, Ram; Huang, Yi-Chiang; Lee, Hsu-Feng; Chang, Ming-Sien; Huang, Wen-Yao

    2017-03-01

    A new novel blue light emitting polymer containing carbazole and anthracene derivatives has been successfully synthesized via polycondensation chemical reaction of diol and difluoro monomers. An effort has been made to raise the band gap of blue light emitter by lowering the conjugation extent in the backbone. The synthesized blue polymer exhibits decent solubility, good process ability, high thermal stability, high glass transition temperature (272 °C) and the decomposition temperature of 358 °C. The UV-vis absorption spectra and photoluminescence spectra depict that the light emission lies in blue region. The solid state photoluminescence (PL) spectra of the polymer (λPL=456 nm) shows red shift (Δλ = 37 nm) as compared with the corresponding solution PL spectra, presumably due to lower intermolecular distance in solid state. The multi-layered polymer light emitting diode was fabricated, using blue polymer with ITO/PEDOT: PSS/BP/LiF/Al architecture. The luminance-voltage (L-V) and current density-voltage (J-V) curves show a maximum luminance of 7544 cd m-2, a maximum emission efficiency of 4.2 cd A-1, a maximum current density of 453 mA cm-2 at a turn-on voltage of 4.5 V. Moreover, the PLED instigate pure blue EL emission, stable at 436 nm with outstanding CIE coordinates of (x = 0.15, y = 0.08), which is close to the pure NTSC blue coordinates of (0.14, 0.08). [Figure not available: see fulltext.

  20. On the use of the chirplet atomic decomposition for characterizing and classifying bedload signals recorded with hydrophones

    NASA Astrophysics Data System (ADS)

    Barrière, J.; Oth, A.; Schenkluhn, R.; Krein, A.

    2013-12-01

    Hydroacoustic measurements are of growing interest for bedload transport monitoring since this indirect technique allows performing high temporal resolution and continuous records contrary to sediments trap data analysis. We aim to test in our project the reliability of such measurements to describe the bedload transport of typical small lowland rivers. Our set-up is constituted by a piezoelectric hydrophone acting as a 'sediment vibration sensor' in contact with a steel plate located on the streambed. In previous similar studies, the signal processing is generally reduced to power spectral analysis to derive a quantitative relationship with the total mass of the transported materials. In view of the high signal to noise ratio of the recorded signals, we intend to improve the processing procedure in order to derive more information on time-varying bedload properties. The waveform of the first signal arrival (flexural wave) is directly proportional to the force and the contact time that the bedload imposes on the plate. According to the Hertz contact theory, grain size and mass could be estimated from acoustic measurements. However, recorded signals after impacts exhibit complex waveforms due to boundary reflections. To identify and characterize the first arrival, we use a high-dimensional signal decomposition method based on the chirplet transform. This algorithm provides an optimal reconstruction of the selected waveform in terms of chirp atom characterized by 7 parameters (generalization of 2-D information obtained by wavelet transform in the time/frequency plane). Afterwards, we performed a hierarchical clustering of reconstructed waveforms and obtain a classification of saltating bedload signals. From the results of two experiments (one artificial and one natural flood event), we observe that this classification is mainly controlled by the central frequency. The frequency of the extracted atom is a key parameter, since it is related to the grain size

  1. An integrated electroactive polymer sensor-actuator: design, model-based control, and performance characterization

    NASA Astrophysics Data System (ADS)

    Hunt, A.; Chen, Z.; Tan, X.; Kruusmaa, M.

    2016-03-01

    Ionic electroactive polymers (IEAPs), particularly ionic polymer-metal composites (IPMCs) and carbon-polymer composites (CPCs), bend when a voltage is applied on their electrodes, and conversely, they generate an electrical signal when subjected to a mechanical bending. In this work we study and compare the capabilities of IPMC and CPC actuators and sensors in closed-loop control applications. We propose and realize an integrated IEAP sensor-actuator design, characterize its performance using three different materials, and compare the results. The design consists of two short IEAP actuators and one sensor mechanically coupled together in a parallel configuration, and an attached rigid extension significantly longer than the IEAPs. This allows the device to be compliant, simple to construct, lightweight, easy to miniaturize, and functionally similar to a one-degree-of-freedom rotational joint. For control design and accurate position sensing in feedback experiments, we adapt physics-based and control-oriented models of actuation and sensing dynamics, and perform experiments to identify their parameters. In performance characterization, both model-based {H}∞ control and proportional-integral control are explored. System responses to step inputs, sinusoids, and random references are measured, and long-duration sinusoidal tracking experiments are performed. The results show that, while IEAP position sensing is stable for only a limited time-span, H ∞ control significantly improves the performance of the device.

  2. Direct characterization of polymer encapsulated CdSe/CdS/ZnS quantum dots

    NASA Astrophysics Data System (ADS)

    Zorn, Gilad; Dave, Shivang R.; Weidner, Tobias; Gao, Xiaohu; Castner, David G.

    2016-06-01

    Surface engineering advances of semiconductor quantum dots (QDs) have enabled their application to molecular labeling, disease diagnostics and tumor imaging. For biological applications, hydrophobic core/shell QDs are transferred into aqueous solutions through the incorporation of water-solubility imparting moieties, typically achieved via direct exchange of the native surface passivating ligands or indirectly through the adsorption of polymers. Although polymeric encapsulation has gained wide acceptance, there are few reports addressing the characterization of the adsorbed polymers and existing theoretical analyses are typically based on simple geometric models. In this work, we experimentally characterize and quantify water-soluble QDs prepared by adsorption of amphiphilic poly(maleic anhydride-alt-1-tetradecene) (PMAT, MW ~ 9000) onto commercially available CdSe/CdS/ZnS (CdSe/CdS/ZnS-PMAT). Using X-ray photoelectron spectroscopy (XPS) we determined that ~ 15 PMAT molecules are adsorbed onto each QD and sum frequency generation (SFG) vibrational spectra were utilized to investigate the mechanism of interaction between PMAT molecules and the QD surface. Importantly, when employed together, these techniques constitute a platform with which to investigate any polymer-nanoparticle complex in general.

  3. The fabrication and characterization of biodegradable HA/PHBV nanoparticle-polymer composite scaffolds.

    PubMed

    Jack, Kevin S; Velayudhan, Shiny; Luckman, Paul; Trau, Matt; Grøndahl, Lisbeth; Cooper-White, Justin

    2009-09-01

    This study reports the fabrication and characterization of nano-sized hydroxyapatite (HA)/poly(hydroxyabutyrate-co-hydroxyvalerate) (PHBV) polymer composite scaffolds with high porosity and controlled pore architectures. These scaffolds were prepared using a modified thermally induced phase-separation technique. This investigation focuses on the effect of fabrication conditions on the overall pore architecture of the scaffolds and the dispersion of HA nanocrystals within the composite scaffolds. The morphologies, mechanical properties and in vitro bioactivity of the composite scaffolds were investigated. It was noted that the pore architectures could be manipulated by varying phase-separation parameters. The HA particles were dispersed in the pore walls of the scaffolds and were well bonded to the polymer. The introduction of HA greatly increased the stiffness and strength, and improved the in vitro bioactivity of the scaffolds. The results suggest these newly developed nano-HA/PHBV composite scaffolds may serve as an effective three-dimensional substrate in bone tissue engineering.

  4. Flame retardant brominated styrene-based polymers. VI. Synthesis and characterization of dibromostyrene graft latices

    SciTech Connect

    Favstritsky, N.A.; Wang, J.L.

    1995-12-01

    Nine dibromostyrene-grafted commercial lattices were prepared in 8 oz bottles by an emulsion polymerization technique. Proper selection of lattices used in conjunction with the dibromostyrene monomer enables production of flame retardant latex products useful in a wide range of coating applications. The prime factor to be considered in the choice of a latex or a latex mixture to be grafted is the glass transition temperature(s) of the polymer(s) in the final latex desired. Lattices chosen for grafting are commercial lattices, such as Rhoplex HA-24 and HA-8, Hystretch V-29, Airflex 465, 4500, 4514 and 4530, Pliolite SBR latex and polybutadiene latex. The graft latex was characterized in terms of glass transition temperature, solids content, bromine content, grafted dibromostyrene and flame retardancy.

  5. Novel polymer anchored Cr(III) Schiff base complexes: Synthesis, characterization and antimicrobial properties

    NASA Astrophysics Data System (ADS)

    Selvi, Canan; Nartop, Dilek

    2012-09-01

    New polymer-bound Schiff bases and Cr(III) complexes have been synthesized by the reaction of 4-benzyloxybenzaldehyde, polymer-bound with 2-aminophenol, 2-amino-4-chlorophenol and 2-amino-4-methylphenol. The structure of polymeric-Schiff bases and their Cr(III) complexes have been characterized by elemental analyses, magnetic measurements, IR, UV-Vis, TG-DTA and 1H-NMR. All these compounds have also been investigated for antibacterial activity by the well-diffusion method against Staphylococcus aureus (RSKK-07035), Shigella dysenteria type 10 (RSKK 1036), Listeria monocytogenes 4b(ATCC 19115, Escherichia coli (ATCC 1230), Salmonella typhi H (NCTC 901.8394), Staphylococcus epidermis (ATCC 12228), Brucella abortus (RSKK-03026), Micrococcs luteus (ATCC 93419, Bacillus cereus sp., Pseudomonas putida sp. and for antifungal activity against Candida albicans (Y-1200-NIH).

  6. Multiscale characterization of chemical–mechanical interactions between polymer fibers and cementitious matrix

    SciTech Connect

    Hernández-Cruz, Daniel; Hargis, Craig W.; Bae, Sungchul; Itty, Pierre A.; Meral, Cagla; Dominowski, Jolee; Radler, Michael J.; Kilcoyne, David A.; Monteiro, Paulo J. M.

    2014-04-01

    Together with a series of mechanical tests, the interactions and potential bonding between polymeric fibers and cementitious materials were studied using scanning transmission X-ray microscopy (STXM) and microtomography (lCT). Experimental results showed that these techniques have great potential to characterize the polymer fiber-hydrated cement-paste matrix interface, as well as differentiating the chemistry of the two components of a bi-polymer (hybrid) fiber the polypropylene core and the ethylene acrylic acid copolymer sheath. Similarly, chemical interactions between the hybrid fiber and the cement hydration products were observed, indicating the chemical bonding between the sheath and the hardened cement paste matrix. Microtomography allowed visualization of the performance of the samples, and the distribution and orientation of the two types of fiber in mortar. Beam flexure tests confirmed improved tensile strength of mixes containing hybrid fibers, and expansion bar tests showed similar reductions in expansion for the polypropylene and hybrid fiber mortar bars.

  7. Synthesis, characterization and magnetic properties of Fe3O4 doped chitosan polymer

    NASA Astrophysics Data System (ADS)

    Karaca, E.; Şatır, M.; Kazan, S.; Açıkgöz, M.; Öztürk, E.; Gürdağ, G.; Ulutaş, D.

    2015-01-01

    Fe3O4 nanoparticles doped into chitosan films were prepared by the solution casting technique. Various samples were synthesized in atmospheric medium and in vacuum. The morphological properties of the samples were characterized by high resolution transmission electron microscopy (HR-TEM) and Scanning Electron Microscopy (SEM). The structural, magnetic, and microwave absorption properties of magnetic chitosan films have been carried out using the Vibrating Sample Magnetometer (VSM) and Ferromagnetic Resonance (FMR). It is shown that the composite polymer behaves like a superparamagnetic material with high blocking temperature. The effective magnetization shows gradual increments with the concentration of dopant Fe3O4 nanoparticles. The microwave absorption characteristic of superparamagnetic composite polymer shows low reflection loss.

  8. Preparation and characterization of lanthanide-azo-dye coordination polymers and polymer thin films via layer-by-layer depositions.

    PubMed

    Han, Li-Wei; Lü, Jian; Liu, Tian-Fu; Gao, Shui-Ying; Cao, Rong

    2010-12-07

    A series of tartrazine-lanthanide dye compounds has been synthesized and characterized. Structural studies reveal that the light rare-earth elements La, Ce, Pr and Nd form coordination compounds with tartrazine ligands in a 1:1 ratio and result in 1-D 'fish-bone' chain-like structures having uncoordinated organosulfonate groups on each side of the chain. However, reactions of tartrazine and heavy rare-earth elements Ho, Er, Tm and Yb, in the presence of auxiliary 1,10-phenanthroline, give new 1-D coordination polymers in which uncoordinated organosulfonate groups are located on the same side of the chains. The tartrazine ligands display similar but slightly different coordination modes in both types of structures and the 1,10-phenanthroline plays a vital role in the formation of heavy rare-earth dye compounds. Based on the knowledge of their structures, the light rare-earth dye compounds were utilized to assemble with positively-charged PEI into multilayer thin films by means of layer-by-layer depositions. The as-synthesized thin films showed enhanced stability and consistency on solid surfaces.

  9. An NDE Approach for Characterizing Quality Problems in Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Roth, Don J.; Baaklini, George Y.; Sutter, James K.; Bodis, James R.; Leonhardt, Todd A.; Crane, Elizabeth A.

    1994-01-01

    Polymer matrix composite (PMC) materials are periodically identified appearing optically uniform but containing a higher than normal level of global nonuniformity as indicated from preliminary ultrasonic scanning. One such panel was thoroughly examined by nondestructive (NDE) and destructive methods to quantitatively characterize the nonuniformity. The NDE analysis of the panel was complicated by the fact that the panel was not uniformly thick. Mapping of ultrasonic velocity across a region of the panel in conjunction with an error analysis was necessary to (1) characterize properly the porosity gradient that was discovered during destructive analyses and (2) account for the thickness variation effects. Based on this study, a plan for future NDE characterization of PMC's is presented to the PMC community.

  10. Synthesis and characterization of nickel and zinc ferrite nanocatalysts for decomposition of CO2 greenhouse effect gas.

    PubMed

    Lin, Kuen-Song; Adhikari, Abhijit Krishna; Wang, Chi-Yu; Hsu, Pei-Ju; Chan, Ho-Yang

    2013-04-01

    The decomposition of CO2 over oxygen deficient nickel ferrite nanoparticles (NFNs) and zinc ferrite nanoparticles (ZFNs) at 573 K was studied. The oxidation states with fine structure of Fe/Ni or Fe/Zn species were also measured in NFNs and ZFNs catalysts, respectively. Oxygen deficiency of catalysts was obtained by reduction in hydrogen. Decomposition of CO2 into carbon and oxygen has been carried out within few minutes when it comes into contact with oxygen deficient catalysts through incorporation of oxygen into ferrite nanoparticles. Oxygen and carbon rather than CO were produced in the decomposition process. The complete decomposition of CO2 was possible because of higher degree of oxygen deficiency andsurface-to-volume ratio of the catalysts. The pre-edge XANES spectra of Fe species in both catalysts exhibit an absorbance feature at 7114 eV for the 1s to 3d transition which is forbidden by the selection rule in case of perfect octahedral symmetry. The EXAFS data showed that the NFNs had two central Fe atoms coordinated by primarily Fe-O and Fe-Fe with bond distances of 1.871 and 3.051 angstroms, respectively. In case of ZFNs these values are 1.889 and 3.062 A, respectively. Methane gas was produced during the reactivation of NFNs by flowing hydrogen gas. Decomposition of CO2, moreover, recovery of valuable methane using heat energy of offgas produced from power generation plant or steel industry is an appealing alternative for energy recovery.

  11. Characterization of 2-(2-Methoxyethoxy)ethanol Substituted Phosphazene Polymers Using Pervaporation, Solubility Parameters and Sorption Studies

    SciTech Connect

    Orme, Christopher Joseph; Klaehn, John Ray; Harrup, Mason Kurt; Lash, Robert Paul; Stewart, Frederick Forrest

    2005-05-01

    Two linear phosphazene polymers were synthesized with differing amounts of hydrophilic 2-(2-methoxyethoxy)ethanol (MEE) and hydrophobic 4-methoxyphenol (MEOP) substituted on the backbone. These high polymers were cast into membranes and their permeability to water, methanol, ethanol, and 2-propanol was evaluated as a function of temperature. An additional polymer with a low content of MEE was studied for water permeation and was characterized by trace flux. At higher levels of MEE on the backbone, fluxes of all solvents increased. Solubility also was found to increase with increasing MEE content for all solvents except water. Unexpectedly, water was found to be less soluble in the higher MEE polymer, although higher membrane fluxes were observed. Diffusion coefficients showed the following trend: methanol 2-propanol > ethanol water. Finally, the affinity of solvents and polymers was discussed in terms of Hansen solubility parameters.

  12. Preparation and characterization of MWCNT nanofiller incorporated polymer composite for lithium battery applications

    NASA Astrophysics Data System (ADS)

    Pradeepa, P.; Raj, S. Edwin; Selvakumar, K.; Sowmya, G.; Prabhu, M. Ramesh

    2015-06-01

    Poly (ethyl methacrylate) based polymer electrolyte films were prepared by solution casting technique incorporating multi-walled carbon nanotube (MWCNT) as filler and characterized using XRD and Ac impedance analysis. The electrical conductivity is increased with increasing filler concentration (upto 6wt %), which is attributed to the formation of charge transfer complexes. The maximum ionic conductivity value is found to be 1.171×10-3 Scm-1 at 303K for PEMA (19wt %) -LiClO4 (8wt %) -MWCNT (6wt %) -PC (67wt %) electrolyte system. The temperature dependent ionic conductivity plot seems to obey Vogel -Tamman-Fulcher relation.

  13. Preparation and characterization of MWCNT nanofiller incorporated polymer composite for lithium battery applications

    SciTech Connect

    Pradeepa, P.; Raj, S. Edwin; Selvakumar, K.; Sowmya, G.; Prabhu, M. Ramesh

    2015-06-24

    Poly (ethyl methacrylate) based polymer electrolyte films were prepared by solution casting technique incorporating multi-walled carbon nanotube (MWCNT) as filler and characterized using XRD and Ac impedance analysis. The electrical conductivity is increased with increasing filler concentration (upto 6wt %), which is attributed to the formation of charge transfer complexes. The maximum ionic conductivity value is found to be 1.171×10{sup −3} Scm{sup −1} at 303K for PEMA (19wt %) -LiClO{sub 4} (8wt %) -MWCNT (6wt %) -PC (67wt %) electrolyte system. The temperature dependent ionic conductivity plot seems to obey Vogel -Tamman-Fulcher relation.

  14. Dynamic characterization of viscoelastic polymer solutions in a lubricated cylinder - Plate apparatus

    NASA Technical Reports Server (NTRS)

    Doremus, P.; Piau, J. M.; Altman, R. L.

    1987-01-01

    The characterization of several viscoelastic lubricants which are oil or water based has been studied in an apparatus consisting of a lubricated cylinder-plate contact. The friction loads were measured as a function of speed. The experimental results show the influence of the molecular weight and of the concentration of the polymeric additive as well as the influence of the viscosity of the oil-base on the load and friction coefficient. Also a test for mechanical degradation was performed on the polymer solutions. Several additives can favor a viscoelastic lubrication.

  15. Characterization of magnetization-induced second harmonic generation in iron oxide polymer nanocomposites.

    PubMed

    Vandendriessche, Stefaan; Valev, Ventsislav K; Verbiest, Thierry

    2012-01-10

    We have measured the magnetization-induced second harmonic generation (MSHG) of a nanocomposite consisting of iron oxide nanoparticles in a polymer film. The existing theoretical framework is extended to include DC magnetic fields in order to characterize the MSHG signal and analyze the measurements. Additionally, magnetic hysteresis loops are measured for four principal polarizer-analyzer configurations, revealing the P(IN)-P(OUT) and S(IN)-P(OUT) polarizer-analyzer configurations to be sensitive to the transverse magnetic field. These results demonstrate the use of MSHG and the applied formalism as a tool to study magnetic nanoparticles and their magnetic properties.

  16. Molecular Engineering of Liquid Crystalline Polymers by Living Polymerization. 22. Synthesis and Characterization of Binary Copolymers

    DTIC Science & Technology

    1992-03-27

    are isomorphic but behave as a non-ideal solution. Poly [( l 5-8)-¢o-( -li: ] X/Y 10 This copolymer is synthesized from a pair of monomers whose parent...Science Case Western Reserve University D T IC Cleveland, OH 44106-2699 E L EC fE 7 Submitted for Publication • APR07 1992 , D in Liquid Crystal March...Crystalline Polymers by Living Polymerization. 22. Synthesis and Characterization of Binary Copolymers Of I l -14 -Cyano-4*-biphenyl)oxy]undecany Vinyl Ether

  17. Synthesis and characterization of a molecularly imprinted polymer for the determination of spiramycin in sheep milk.

    PubMed

    García Mayor, M A; Paniagua González, G; Garcinuño Martínez, R M; Fernández Hernando, P; Durand Alegría, J S

    2017-04-15

    A series of molecularly imprinted polymers (MIPs) comprising reactionary sites which are complementary to macrolide antibiotic spiramycin (SPI) were synthetized by noncovalent bulk polymerization technique. MIPs were synthesized under different polymerization process and their recognition efficiency was evaluated in binding studies in comparison with non-imprinted polymers. The best MIP was morphologically characterized and equilibrium assays were carried out. The MIP was evaluated as a sorbent for extraction and preconcentration of SPI from aqueous and sheep milk samples, and an off-line MISPE method followed by high-performance liquid chromatography with UV diode-array detection was established. Good linearity were obtained for SPI in a range of 24-965μgkg(-1) and the average recoveries at three spiked levels in milk samples were higher than 90% (RSD<5%). Limit of quantification was 24.1μgkg(-1). Cross-reactivity studies from other macrolides with similar structure were tested. The optimum imprinted polymer showed a good selectivity and affinity for SPI, demonstrating the potential of the proposed MISPE for rapid, sensitive and effective sample pretreatment for selective determination of SPI in sheep milk samples.

  18. Characterization of Nanoclay Orientation in Polymer Nanocomposite Film by Small-angle X-ray Scattering

    SciTech Connect

    P Nawani; C Burger; L Rong; B Chu; B Hsiao; A Tsou; W Weng

    2011-12-31

    The orientation distribution of layer-shaped nanoclays (e.g. organoclays and pristine clays) dispersed in a polymer matrix is an important parameter to control the properties of polymer nanocomposites. In this study, we demonstrate that the use of multi-directional 2-D small-angleX-rayscattering (SAXS) can quantitatively describe the orientation distribution of organoclays (e.g. Cloisite C20A) in melt-pressed nanocompositefilms, containing ethylene-vinyl acetate (EVA) copolymers as polymer matrices. Different weight fractions of organoclays were used to alter the orientation profile of nanocompositefilms, in which the dispersion and morphology of organoclays were also characterized by complementary 2-D and 3-D transmission electron microscopy (TEM). All nanocomposites exhibited mixed intercalation/exfoliation clay morphology, where the intercalated structure possessed partial orientation parallel to the in-plane direction of the film. The higher content of the clay loading showed a higher clay orientation. A simple analytical scheme for SAXS data analysis to determine the orientation parameter (P{sub 2}) was demonstrated, the results of which are in agreement with the gas permeation properties of the nanocompositefilms.

  19. Synthesis and characterization of MAA-based molecularly-imprinted polymer (MIP) with D-glucose template

    NASA Astrophysics Data System (ADS)

    Yanti; Nurhayati, T.; Royani, I.; Widayani; Khairurrijal

    2016-08-01

    In this study, molecularly-imprinted polymer (MIP) was prepared by using a D-glucose template and a methacrylic acid (MAA) functional monomer. The obtained MIP was characterized using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy techniques to study the template imprinting results. For comparison, similar characterizations were also carried out for the respective non imprinted polymer (NIP). It was found that the polymer has semicrystalline structure, with crystallinity degree of the unleached- polymer, the NIP, and the MIP is 62.40%, 62.97%, and 63.47%, respectively. XRD patterns showed that the intensity peaks increases as D-glucose content decreases. The FTIR spectra of the MIP indicate the detail interaction of template and functional monomer.

  20. Characterization of physicochemical properties of naproxen systems with amorphous beta-cyclodextrin-epichlorohydrin polymers.

    PubMed

    Mura, P; Faucci, M T; Maestrelli, F; Furlanetto, S; Pinzauti, S

    2002-08-01

    Ground mixtures of naproxen with amorphous beta-cyclodextrin-epichlorohydrin soluble (betaCd-EPS) or insoluble cross-linked (betaCd-EPI) polymers were investigated for both solid phase characterization (Differential Scanning Calorimetry, powder X-ray Diffractometry) and dissolution properties (dispersed amount method). The effect of different grinding conditions and of drug-to-carrier ratio was also evaluated. Co-grinding induced a decrease in drug crystallinity to an extent which depended on the grinding time, and was most pronounced for the cross-linked insoluble polymer, particularly in combinations at the lowest drug content. Both cyclodextrin polymers were more effective in improving the naproxen dissolution properties, not only than the parent betaCd but also than hydroxyalkyl-derivatives, and their performance was almost comparable to that of methyl-derivatives, previously found as the best carriers for naproxen. Dissolution efficiencies of naproxen from physical mixtures with betaCd-EPS, thanks to the high water solubility of this Cd-derivative, were up to three times higher than those from the corresponding products with betaCd-EPI. However this difference in their performance became much less evident in co-ground products and tended to progressively diminish with increasing the polymer content in the mixture, according to the better amorphizing power shown by betaCd-EPI during the co-grinding process. The 10/90 (w/w) drug-carrier co-ground products exhibited the best dissolution properties, giving dissolution efficiencies about 30 times higher than that of naproxen alone.

  1. Synthesis, characterization and analytical applications of Ni(II)-ion imprinted polymer

    NASA Astrophysics Data System (ADS)

    Singh, D. K.; Mishra, Shraddha

    2010-10-01

    Ion recognition-based separation techniques have received much attention because of their high selectivity for target ions. In this study, we have prepared a novel ion imprinted polymer (IIP) to remove nickel ions with high selectivity. The imprinted polymer was prepared by copolymerization of 2-hydroxy ethyl methacrylate (HEMA) with nickel vinylbenzoate complex in the presence of ethylene glycol dimethacrylate (EGDMA) as a crosslinker. The polymerization was carried out in bulk with free radical initiation using 2-methoxy ethanol as a solvent and porogen. The adsorbed nickel was completely eluted with 15 mL of 1 M HCl. Control polymer was also prepared by similar experimental conditions without using imprint ion. The above synthesized polymers were characterized by surface area measurements, FT-IR, microanalysis and SEM analysis. The adsorption capacity of IIP and CP was found to be 1.51 and 0.65 mmol g -1, respectively. The optimal pH for quantitative enrichment was 6.5. Nature of eluent, eluent concentration and eluent volume were also studied. The relative selectivity factor ( αr) values of Ni(II)/Zn(II), Ni(II)/Cu(II) and Ni(II)/Co(II) were 78.6, 111.1 and 91.6, respectively. Five replicate determinations of 30 μg L -1 of Ni(II) gave a mean absorbance of 0.067 with a relative standard deviation of 1.06%. The lowest concentration determined by GTA-AAS below which the recovery becomes non-quantitative is 6 μg L -1. IIP was tested for removal of Ni(II) from sea water sample.

  2. Decomposition techniques

    USGS Publications Warehouse

    Chao, T.T.; Sanzolone, R.F.

    1992-01-01

    Sample decomposition is a fundamental and integral step in the procedure of geochemical analysis. It is often the limiting factor to sample throughput, especially with the recent application of the fast and modern multi-element measurement instrumentation. The complexity of geological materials makes it necessary to choose the sample decomposition technique that is compatible with the specific objective of the analysis. When selecting a decomposition technique, consideration should be given to the chemical and mineralogical characteristics of the sample, elements to be determined, precision and accuracy requirements, sample throughput, technical capability of personnel, and time constraints. This paper addresses these concerns and discusses the attributes and limitations of many techniques of sample decomposition along with examples of their application to geochemical analysis. The chemical properties of reagents as to their function as decomposition agents are also reviewed. The section on acid dissolution techniques addresses the various inorganic acids that are used individually or in combination in both open and closed systems. Fluxes used in sample fusion are discussed. The promising microwave-oven technology and the emerging field of automation are also examined. A section on applications highlights the use of decomposition techniques for the determination of Au, platinum group elements (PGEs), Hg, U, hydride-forming elements, rare earth elements (REEs), and multi-elements in geological materials. Partial dissolution techniques used for geochemical exploration which have been treated in detail elsewhere are not discussed here; nor are fire-assaying for noble metals and decomposition techniques for X-ray fluorescence or nuclear methods be discussed. ?? 1992.

  3. Characterization of low molecular weight alkoxylated polymers using long column SFC/MS and an image analysis based quantitation approach.

    PubMed

    Pinkston, J David; Marapane, Suresh B; Jordan, Glenn T; Clair, B David

    2002-10-01

    The utility of low viscosity mobile phases and long chromatographic columns for complex polymer analysis is demonstrated. We use long column supercritical fluid chromatography/mass spectrometry (SFC/MS) with electrospray ionization (ESI) to characterize a variety of complex, low molecular weight polymers. When quantitative analysis is desired, the resulting three-dimensional (time, intensity, and mass-to-charge ratio [m/z]) data are converted to images. Custom image analysis software is used to detect and integrate peaks in arbitrarily defined regions of the time-m/z map. These integrated peak volumes can be used to quantitate distinct component classes of the polymer mixtures.

  4. Viscoelastic characterization of thin-film polymers exposed to low Earth orbit

    NASA Technical Reports Server (NTRS)

    Letton, Alan; Farrow, Allan; Strganac, Thomas

    1993-01-01

    The materials made available through the Long Duration Exposure Facility (LDEF) satellite provide a set of specimens that can be well characterized and have a known exposure history with reference to atomic oxygen and ultraviolet radiation exposure. Mechanical characteristics measured from control samples and exposed samples provide a data base for predicting the behavior of polymers in low earth orbit. Samples of 1.0 mil thick low density polyethylene were exposed to the low earth orbit environment for a period of six years. These materials were not directly exposed to ram atomic oxygen and offer a unique opportunity for measuring the effect of atomic oxygen and UV radiation on mechanical properties with little concern to the effect of erosion. The viscoelastic characteristics of these materials were measured and compared to the viscoelastic characteristics of control samples. To aid in differentiating the effects of changes in crystallinity resulting from thermal cycling, from the effects of changes in chemical structure resulting from atomic oxygen/UV attack to the polymer, a second set of control specimens, annealed to increase crystallinity, were measured as well. The resulting characterization of these materials will offer insight into the impact of atomic oxygen/UV on the mechanical properties of polymeric materials. The viscoelastic properties measured for the control, annealed, and exposed specimens were the storage and loss modulus as a function of frequency and temperature. From these datum is calculated the viscoelastic master curve derived using the principle of time/temperature superposition. Using the master curve, the relaxation modulus is calculated using the method of Ninomiya and Ferry. The viscoelastic master curve and the stress relaxation modulus provide a direct measure of the changes in the chemical or morphological structure. In addition, the effect of these changes on long-term and short-term mechanical properties is known directly. It

  5. Size control and characterization of wustite (core)/spinel (shell) nanocubes obtained by decomposition of iron oleate complex.

    PubMed

    Hai, Hoang Tri; Yang, Hai Tao; Kura, Hiroaki; Hasegawa, Daiji; Ogata, Yasunobu; Takahashi, Migaku; Ogawa, Tomoyuki

    2010-06-01

    Monodisperse wustite (core)/spinel (shell) nanocubes with controllable size from 9 to 22 nm were synthesized by the decomposition of iron oleate complex at high temperature. The composition of the nanocubes was confirmed by X-ray diffraction and magnetic analysis, meanwhile the distributions of wustite and spinel phases within the nanocubes were directly observed by high resolution transmission electron microscopy using the dark-field image technique. The core/shell structure is quite unique, in which spinel phase is distributed not only preferentially on the surface, but also in the interior, while almost all of the wustite phase is located in the core of the nanocubes. The formation of wustite is inherent in the decomposition of the iron oleate complex, as indirectly inferred through the detection of a huge quantity of carbon monoxide generated from the reactor.

  6. Radiation grafted membranes for polymer electrolyte fuel cells, ex situ and in situ characterization

    SciTech Connect

    Scherer, G.G.; Buchi, F.N.; Gupta, B.

    1993-12-31

    Proton conducting membranes for polymer electrolyte fuel cells were prepared by radiation grafting of styrene/divinylbenzene onto Telon-FEP films and subsequent sulfonation. Films with degrees of grafting up to 50% were obtained and characterized FTIR-ATR with respect to their homogeneity, by DSC and TGA with respect to their thermal properties. After sulfonation thermal stability was again probed by TGA in combination with one-line FTIR and MS. Water uptake and protonic resistivity were determined after pretreatment in boiling water. The decrease in resistivity with increasing degree of grafting is mainly due to an increasing proton mobility. The membranes were tested in H{sub 2}/O{sub 2} fuel cells (ambient pressure, 60 to 90{degrees}C) with respect to their short- and long-term (up to 1000 h) polarization performance. The results of the ex and in situ characterization will be presented and discussed.

  7. Synthesis and characterization of inorganic polymers from the alkali activation of an aluminosilicate

    NASA Astrophysics Data System (ADS)

    González, C. P.; Montaño, A. M.; González, A. K.; Ríos, C. A.

    2014-06-01

    This paper presents the results of the synthesis and characterization of inorganic polymers (IP) from aluminosilicates: bentonite (BT) and pumice (PP). The synthesis of IP, was carried out by two methods involving alkaline activation, at room temperature and 80 ± 5 °C, using as activating agent sodium silicate both commercial and analytical (Na2SiO3). Sodium hydroxide (NaOH) at 3 M, 7 M and 12 M was added. A lower degree of polymerization was obtained by using analytical precursors subjected to room temperature and 80 ± 5°C. Replacement of heating by the use of the commercial activating agent with greater alkalinity allows the formation of a 3D network. The materials were structurally characterized by FTIR spectroscopy with Attenuated Reflectance (ATR), Scanning Electron Microscope (SEM) and X -ray diffraction (DRX).

  8. Synthesis and Characterization of Sulfonated Graphene Oxide Nanofiller for Polymer Electrolyte Membrane

    NASA Astrophysics Data System (ADS)

    Ch'ng, Y. Y.; Loh, K. S.; Daud, W. R. W.; Mohamad, A. B.

    2016-11-01

    In this study, sulfonated graphene oxide (SGO) nanocomposite were produced as potential nanofiller to improve the properties of polymer electrolyte membrane (PEM) for fuel cell applications. The GO is produced by modified Hummers's method and the as-synthesized GO was used to prepare SGO with three distinctive precursors, namely 3- mercaptomethoxysilane (MPTMS), sulfanilic acid (SA) and butane sultone (BS). The SGO samples were characterized with several physical characterization techniques (XRD, FTIR, SEM-EDX and XPS) to provide the insights into the morphology; the state of homogenization; the crystallography and the functional groups. The experimental result indicated that the sulfonic acid group has been successfully incorporated with GO and can be used as filler in PEM.

  9. Synthesis and characterization of hybrid molecularly imprinted polymer (MIP) membranes for removal of methylene blue (MB).

    PubMed

    Asman, Saliza; Yusof, Nor Azah; Abdullah, Abdul Halim; Haron, Md Jelas

    2012-02-15

    This work reports the synthesis and characterization of a hybrid molecularly imprinted polymer (MIP) membrane for removal of methylene blue (MB) in an aqueous environment. MB-MIP powders were hybridized into a polymer membrane (cellulose acetate (CA) and polysulfone (PSf)) after it was ground and sieved (using 90 µm sieve). MB-MIP membranes were prepared using a phase inversion process. The MB-MIP membranes were characterized using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). Parameters investigated for the removal of MB by using membrane MB-MIP include pH, effect of time, concentration of MB, and selectivity studies. Maximum sorption of MB by PSf-MB-MIP membranes and CA-MB-MIP membranes occurred at pH 10 and pH 12, respectively. The kinetic study showed that the sorption of MB by MB-MIP membranes (PSf-MB-MIP and CA-MB-MIP) followed a pseudo-second-order-model and the MB sorption isotherm can be described by a Freundlich isotherm model.

  10. Analysis of the finite deformation response of shape memory polymers: I. Thermomechanical characterization

    NASA Astrophysics Data System (ADS)

    Volk, Brent L.; Lagoudas, Dimitris C.; Chen, Yi-Chao; Whitley, Karen S.

    2010-07-01

    This study presents the analysis of the finite deformation response of a shape memory polymer (SMP). This two-part paper addresses the thermomechanical characterization of SMPs, the derivation of material parameters for a finite deformation phenomenological model, the numerical implementation of such a model, and the predictions from the model with comparisons to experimental data. Part I of this work presents the thermomechanical characterization of the material behavior of a shape memory polymer. In this experimental investigation, the vision image correlation system, a visual-photographic apparatus, was used to measure displacements in the gauge area. A series of tensile tests, which included nominal values of the extension of 10%, 25%, 50%, and 100%, were performed on SMP specimens. The effects on the free recovery behavior of increasing the value of the applied deformation and temperature rate were considered. The stress-extension relationship was observed to be nonlinear for increasing values of the extension, and the shape recovery was observed to occur at higher temperatures upon increasing the temperature rate. The experimental results, aided by the advanced experimental apparatus, present components of the material behavior which are critical for the development and calibration of models to describe the response of SMPs.

  11. New biosourced chiral molecularly imprinted polymer: Synthesis, characterization, and evaluation of the recognition capacity of methyltestosterone.

    PubMed

    Saadaoui, Asma; Sanglar, Corinne; Medimagh, Raouf; Bonhomme, Anne; Baudot, Robert; Chatti, Saber; Marque, Sylvain; Prim, Damien; Zina, Mongia Saïd; Casabianca, Herve

    2017-04-01

    New biosourced chiral cross-linkers were reported for the first time in the synthesis of methyltestosterone (MT) chiral molecularly imprinted polymers (cMIPs). Isosorbide and isomannide, known as 1,4:3,6-dianhydrohexitols, were selected as starting diols. The cMIPs were synthesized following a noncovalent approach via thermal radical polymerization and monitored by Raman spectroscopy. These cross-linkers were fully characterized by (1) H and (13) C nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry. The cross-polarization magic angle spinning (13) C NMR, Fourier transform infrared spectroscopy, scanning electron microscopy, and specific surface areas following the Brunauer-Emmett-Teller (BET) method were used to characterize the cMIPs. The effect of stereochemistry of cross-linkers on the reactivity of polymerization, morphology, and adsorption-recognition properties of the MIP was evaluated. The results showed that the cMIP exhibited an obvious improvement in terms of rebinding capacity for MT as compared with the nonimprinted polymer (NIP). The highest binding capacity was observed for cMIP-Is (27.298 mg g(-1) ) for high concentrations (500 mg L(-1) ). However, the isomannide homologue cMIP-Im showed higher recovery-up to 65% and capacity for low concentrations (15 mg L(-1) ). The experimental data were properly fitted by the Freundlich adsorption isothermal model.

  12. Synthesis and characterization of polymer layers for control of fluid transport

    NASA Astrophysics Data System (ADS)

    Vatansever, Fehime

    The level of wetting of fiber surface with liquids is an important characteristic of fibrous materials. It is related to fiber surface energy and the structure of the material. Surface energy can be changed by surface modification via the grafting methodologies that have been reported for introducing new and stable functionality to fibrous substrates without changing bulk properties. Present work is dedicated to synthesis and characterization of macromolecular layers grafted to fiber surface in order to achieve directional liquid transport for the modified fabric. Modification technique used here is based on formation of stable polymer layer on fabric surface using "grafting to" technique. Specifically, modification of fabric with wettability gradient for facilitated one way-liquid transport, and pointed modification of yarn-based channels on textile microfluidic device for directional liquid transport are reported here. First, fabric was activated with alkali (NaOH) solution. Second, poly (glycidyl methacrylate) (PGMA) was deposited on fabric as an anchoring layer. Finally, polymers of interest were grafted to surface through the epoxy functionality of PGMA. Effect of polymer grafting on the wicking property of the fabric has been evaluated by vertical wicking technique at the each step of surface modification. The results shows that wicking performance of fabric can be altered by grafting of a thin nanoscale polymeric film. For the facilitated liquid transport, the gradient polymer coating was created using "grafting to" technique and its dependence on the grafting temperature. Wettability gradient from hydrophilic to hydrophobic (change in water contact angle from 0 to 140 degrees on fabric) was achieved by grafting of polystyrene (PS) and polyacrylic acid (PAA) sequentially with concentration gradient. This study proposes that fabric with wettability gradient property can be used to transfer sweat from skin and support moisture management when it is used in a

  13. Woodland Decomposition.

    ERIC Educational Resources Information Center

    Napier, J.

    1988-01-01

    Outlines the role of the main organisms involved in woodland decomposition and discusses some of the variables affecting the rate of nutrient cycling. Suggests practical work that may be of value to high school students either as standard practice or long-term projects. (CW)

  14. Development and characterization of adjustable refractive index scattering epoxy acrylate polymer layers

    NASA Astrophysics Data System (ADS)

    Eiselt, Thomas; Preinfalk, Jan; Gleißner, Uwe; Lemmer, Uli; Hanemann, Thomas

    2016-09-01

    This work presents different polymer diffusing films for optical components. In optical applications it is sometimes important to have a film with an adjusted refractive index, scattering properties and a low surface roughness. These diffusing films can be used to increase the efficiency of optical components like organic light emitting diodes (OLEDs). In this study three different epoxy acrylate mixtures containing Syntholux 291 EA, bisphenol a glycerolate dimethacrylate, Sartomer SR 348 L are characterized and optimized with different additives. The adjustable refractive index of the material is achieved with a chemical doping by 9-vinylcarbazole. Titanium nanoparticles in the mixtures generate light scattering and increase the refractive index additionally. To prevent sedimentation and agglomeration of these nanoparticles, a stabilization agent [2-(2-methoxyethoxy)ethoxy]acetic acid is added to the mixture. Other ingredients are a UV-starter and thermal starter for the radical polymerization. A high power stirrer (ultraturrax) is used to mix and disperse all chemical substances together to a homogenous mixture. The viscosity behavior of the mixtures is an important property for the selection of the production method and gets characterized. After the mixing, the monomer mixture is applied on glass substrates by blade coating or screen printing. To initiate the chain growing (polymerization) the produced films are irradiated for 10 minutes long with UV light (UV LED Spot Hönle, 405 nm). After this step a final post bake from the layers in the oven (150°C, 30 min.) is operated. Light transmission measurements (UV-Vis) of the polymer matrix and roughness measurements complement the characterization.

  15. Piezoelectric Polymers

    NASA Technical Reports Server (NTRS)

    Harrison, J. S.; Ounaies, Z.; Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    The purpose of this review is to detail the current theoretical understanding of the origin of piezoelectric and ferroelectric phenomena in polymers; to present the state-of-the-art in piezoelectric polymers and emerging material systems that exhibit promising properties; and to discuss key characterization methods, fundamental modeling approaches, and applications of piezoelectric polymers. Piezoelectric polymers have been known to exist for more than forty years, but in recent years they have gained notoriety as a valuable class of smart materials.

  16. Synthesis, characterization and optical properties of polymer-based ZnS nanocomposites.

    PubMed

    Tiwari, A; Khan, S A; Kher, R S; Dhoble, S J; Chandel, A L S

    2016-03-01

    Nanostructured polymer-semiconductor hybrid materials such as ZnS-poly(vinyl alcohol) (ZnS-PVA), ZnS-starch and ZnS-hydroxypropylmethyl cellulose (Zns-HPMC) are synthesized by a facile aqueous route. The obtained nanocomposites are characterized using various techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), UV/vis spectroscopy and photoluminescence (PL). XRD studies confirm the zinc blende phase of the nanocomposites and indicate the high purity of the samples. SEM studies indicate small nanoparticles clinging to the surface of a bigger particle. The Energy Dispersive Analysis by X-rays (EDAX) spectrum reveals that the elemental composition of the nanocomposites consists primarily of Zn:S. FTIR studies indicate that the polymer matrix is closely associated with ZnS nanoparticles. The large number of hydroxyl groups in the polymer matrix facilitates the complexation of metal ions. The absorption spectra of the specimens show a blue shift in the absorption edge. The spectrum reveals an absorption edge at 320, 310 and 325 nm, respectively. PL of nanocomposites shows broad peaks in the violet-blue region (420-450 nm). The emission intensity changes with the nature of capping agent. The PL intensity of ZnS-HPMC nanocomposites is found to be highest among the studied nanocomposites. The results clearly indicate that hydroxyl-functionalized HPMC is much more effective at nucleating and stabilizing colloidal ZnS nanoparticles in aqueous suspensions compared with PVA and starch.

  17. Mechanical characterization and structural analysis of recycled fiber-reinforced-polymer resin-transfer-molded beams

    NASA Astrophysics Data System (ADS)

    Tan, Eugene Wie Loon

    1999-09-01

    The present investigation was focussed on the mechanical characterization and structural analysis of resin-transfer-molded beams containing recycled fiber-reinforced polymers. The beams were structurally reinforced with continuous unidirectional glass fibers. The reinforcing filler materials consisted entirely of recycled fiber-reinforced polymer wastes (trim and overspray). The principal resin was a 100-percent dicyclo-pentadiene unsaturated polyester specially formulated with very low viscosity for resin transfer molding. Variations of the resin transfer molding technique were employed to produce specimens for material characterization. The basic materials that constituted the structural beams, continuous-glass-fiber-reinforced, recycled-trim-filled and recycled-overspray-filled unsaturated polyesters, were fully characterized in axial and transverse compression and tension, and inplane and interlaminar shear, to ascertain their strengths, ultimate strains, elastic moduli and Poisson's ratios. Experimentally determined mechanical properties of the recycled-trim-filled and recycled-overspray-filled materials from the present investigation were superior to those of unsaturated polyester polymer concretes and Portland cement concretes. Mechanical testing and finite element analyses of flexure (1 x 1 x 20 in) and beam (2 x 4 x 40 in) specimens were conducted. These structurally-reinforced specimens were tested and analyzed in four-point, third-point flexure to determine their ultimate loads, maximum fiber stresses and mid-span deflections. The experimentally determined load capacities of these specimens were compared to those of equivalent steel-reinforced Portland cement concrete beams computed using reinforced concrete theory. Mechanics of materials beam theory was utilized to predict the ultimate loads and mid-span deflections of the flexure and beam specimens. However, these predictions proved to be severely inadequate. Finite element (fracture propagation

  18. Structural characterization of polymers by MALDI spiral-TOF mass spectrometry combined with Kendrick mass defect analysis.

    PubMed

    Sato, Hiroaki; Nakamura, Sayaka; Teramoto, Kanae; Sato, Takafumi

    2014-08-01

    High-resolution mass spectrometry (HRMS) continues to play an important role in the compositional characterization of larger organic molecules. In the field of polymer characterization, however, the application of HRMS has made only slow progress because of lower compatibility between matrix-assisted laser desorption/ionization (MALDI) and ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICRMS). In this study, a newly developed type of MALDI high-resolution time-of-flight mass spectrometry (TOFMS) with a spiral ion trajectory (MALDI spiral-TOFMS) was applied to the structural and compositional characterization of polymers. To create a graphical distribution of polymer components on a two-dimensional plot converted from complex mass spectra, we adopted a slightly modified Kendrick mass defect (KMD) analysis based on accurate masses determined using spiral-TOFMS. By setting the Kendrick mass scale based on the mass of the repeating units of a given polymer, components with common repeat units lined up in the horizontal direction on the KMD plot, whereas those components with different structures were shifted vertically. This combination of MALDI spiral-TOFMS measurement and KMD analysis enabled the successful discrimination of the polymer components in a blend of poly(alkylene oxide)s, the compositional analysis of poly(ethylene oxide)/poly(propylene oxide) block copolymers, and profiling of the end-group distribution of poly(ε-caprolactone)s synthesized under different conditions.

  19. Antimicrobial N-halamine polymers and coatings: a review of their synthesis, characterization, and applications.

    PubMed

    Hui, Franck; Debiemme-Chouvy, Catherine

    2013-03-11

    Antimicrobial N-halamine polymers and coatings have been studied extensively over the past decade thanks to their numerous qualities such as effectiveness toward a broad spectrum of microorganisms, long-term stability, regenerability, safety to humans and environment and low cost. In this review, recent developments are described by emphasizing the synthesis of polymers and/or coatings having N-halamine moieties. Actually, three main approaches of preparation are given in detail: polymerization, generation by electrochemical route with proteins as monomers and grafting with precursor monomers. Identification and characterization of the formation of the N-halamine bonds (>N-X with X = Cl or Br or I) by physical techniques such as Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and by chemical reactions are described. In order to check the antimicrobial activity of the N-halamine compounds, bacterial tests are also described. Finally, some examples of application of these N-halamines in the water treatment, paints, healthcare equipment, and textile industries are presented and discussed.

  20. Recycling WEEE: Polymer characterization and pyrolysis study for waste of crystalline silicon photovoltaic modules.

    PubMed

    Dias, Pablo; Javimczik, Selene; Benevit, Mariana; Veit, Hugo

    2017-02-01

    Photovoltaic (PV) modules contain both valuable and hazardous materials, which makes its recycling meaningful economically and environmentally. In general, the recycling of PV modules starts with the removal of the polymeric ethylene-vinyl acetate (EVA) resin using pyrolysis, which assists in the recovery of materials such as silicon, copper and silver. The pyrolysis implementation, however, needs improvement given its importance. In this study, the polymers in the PV modules were characterized by Fourier transform infrared spectroscopy (FTIR) and the removal of the EVA resin using pyrolysis has been studied and optimized. The results revealed that 30min pyrolysis at 500°C removes >99% of the polymers present in photovoltaic modules. Moreover, the behavior of different particle size milled modules during the pyrolysis process was evaluated. It is shown that polymeric materials tend to remain at a larger particle size and thus, this fraction has the greatest mass loss during pyrolysis. A thermo gravimetric analysis (TGA) performed in all polymeric matter revealed the optimum pyrolysis temperature is around 500°C. Temperatures above 500°C continue to degrade matter, but mass loss rate is 6.25 times smaller. This study demonstrates the use of pyrolysis can remove >99% of the polymeric matter from PV modules, which assists the recycling of this hazardous waste and avoids its disposal.

  1. Interdigitated silver-polymer-based antibacterial surface system activated by oligodynamic iontophoresis - an empirical characterization study.

    PubMed

    Shirwaiker, Rohan A; Wysk, Richard A; Kariyawasam, Subhashinie; Voigt, Robert C; Carrion, Hector; Nembhard, Harriet Black

    2014-02-01

    There is a pressing need to control the occurrences of nosocomial infections due to their detrimental effects on patient well-being and the rising treatment costs. To prevent the contact transmission of such infections via health-critical surfaces, a prophylactic surface system that consists of an interdigitated array of oppositely charged silver electrodes with polymer separations and utilizes oligodynamic iontophoresis has been recently developed. This paper presents a systematic study that empirically characterizes the effects of the surface system parameters on its antibacterial efficacy, and validates the system's effectiveness. In the first part of the study, a fractional factorial design of experiments (DOE) was conducted to identify the statistically significant system parameters. The data were used to develop a first-order response surface model to predict the system's antibacterial efficacy based on the input parameters. In the second part of the study, the effectiveness of the surface system was validated by evaluating it against four bacterial species responsible for several nosocomial infections - Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Enterococcus faecalis - alongside non-antibacterial polymer (acrylic) control surfaces. The system demonstrated statistically significant efficacy against all four bacteria. The results indicate that given a constant total effective surface area, the system designed with micro-scale features (minimum feature width: 20 μm) and activated by 15 μA direct current will provide the most effective antibacterial prophylaxis.

  2. Remotely detected NMR for the characterization of flow and fast chromatographic separations using organic polymer monoliths.

    PubMed

    Teisseyre, Thomas Z; Urban, Jiri; Halpern-Manners, Nicholas W; Chambers, Stuart D; Bajaj, Vikram S; Svec, Frantisek; Pines, Alexander

    2011-08-01

    An application of remotely detected magnetic resonance imaging is demonstrated for the characterization of flow and the detection of fast, small molecule separations within hypercrosslinked polymer monoliths. The hyper-cross-linked monoliths exhibited excellent ruggedness, with a transit time relative standard deviation of less than 2.1%, even after more than 300 column volumes were pumped through at high pressure and flow. Magnetic resonance imaging enabled high-resolution intensity and velocity-encoded images of mobile phase flow through the monolith. The images confirm that the presence of a polymer monolith within the capillary disrupts the parabolic laminar flow profile that is characteristic of mobile phase flow within an open tube. As a result, the mobile phase and analytes are equally distributed in the radial direction throughout the monolith. Also, in-line monitoring of chromatographic separations of small molecules at high flow rates is shown. The coupling of monolithic chromatography columns and NMR provides both real-time peak detection and chemical shift information for small aromatic molecules. These experiments demonstrate the unique power of magnetic resonance, both direct and remote, in studying chromatographic processes.

  3. Microencapsulation of phosphogypsum into a sulfur polymer matrix: physico-chemical and radiological characterization.

    PubMed

    López, Félix A; Gázquez, Manuel; Alguacil, Francisco José; Bolívar, Juan Pedro; García-Díaz, Irene; López-Coto, Israel

    2011-08-15

    The aim of this work is to prepare a new type of phosphogypsum-sulfur polymer cements (PG-SPC) to be utilised in the manufacture of building materials. Physico-chemical and radiological characterization was performed in phosphogypsum and phosphogypsum-sulfur polymer concretes and modeling of exhalation rates has been also carried out. An optimized mixture of the materials was obtained, the solidified material with optimal mixture (sulfur/phosphogypsum=1:0.9, phosphogypsum dosage=10-40 wt.%) results in highest strength (54-62 MPa) and low total porosity (2.8-6.8%). The activity concentration index (I) in the PG-SPC is lower than the reference value in the most international regulations and; therefore, these cements can be used without radiological restrictions in the manufacture of building materials. Under normal conditions of ventilation, the contribution to the expected radon indoor concentration in a standard room is below the international recommendations, so the building materials studied in this work can be applied to houses built up under normal ventilation conditions. Additionally, and taking into account that the PG is enriched in several natural radionuclides as (226)Ra, the leaching experiments have demonstrated that environmental impact of the using of SPCs cements with PG is negligible.

  4. Preparation and characterization of aqueous polyurethane oil/polyacrylate latex interpenetrating polymer network

    NASA Astrophysics Data System (ADS)

    Zhou, M. M.; Ma, L. L.; Du, J.; Cao, F.; Xiao, J. J.

    2015-07-01

    A series of aqueous polyurethane oil (network I)/polyacrylate (network II) latex interpenetrating polymer networks (LIPNs) were synthesized via the technology of latex interpenetrating polymer network combined seed emulsion polymerization process. Fourier transform infrared (FTIR) spectroscopy, laser particle size distributing analyzer and universal tension machine were utilized to characterize the bulk structures and mechanical properties of LIPNs. For used as damping material, the damping performance of LIPNs were analyzed by dynamic mechanical analysis (DMA). It was found that the damping temperature region of LIPN was wider than those of aqueous polyurethane oil, the temperature region with greater tanδ changed with the TPGDA content and hard-/soft-segment mass weight ratio (mMMA/mBA) and the glass transition temperature (Tg) of the network I and network II in LIPN occurred within shift each other, even overlap with increasing mMMA/mBA value. The results show that LIPNs synthesized through the combined process have greater tanδ and wider damping temperature region, which is suitable for the use of damping coatings.

  5. Nonlinear viscoelastic characterization of polymer materials using a dynamic-mechanical methodology

    NASA Technical Reports Server (NTRS)

    Strganac, Thomas W.; Payne, Debbie Flowers; Biskup, Bruce A.; Letton, Alan

    1995-01-01

    Polymer materials retrieved from LDEF exhibit nonlinear constitutive behavior; thus the authors present a method to characterize nonlinear viscoelastic behavior using measurements from dynamic (oscillatory) mechanical tests. Frequency-derived measurements are transformed into time-domain properties providing the capability to predict long term material performance without a lengthy experimentation program. Results are presented for thin-film high-performance polymer materials used in the fabrication of high-altitude scientific balloons. Predictions based upon a linear test and analysis approach are shown to deteriorate for moderate to high stress levels expected for extended applications. Tests verify that nonlinear viscoelastic response is induced by large stresses. Hence, an approach is developed in which the stress-dependent behavior is examined in a manner analogous to modeling temperature-dependent behavior with time-temperature correspondence and superposition principles. The development leads to time-stress correspondence and superposition of measurements obtained through dynamic mechanical tests. Predictions of material behavior using measurements based upon linear and nonlinear approaches are compared with experimental results obtained from traditional creep tests. Excellent agreement is shown for the nonlinear model.

  6. Preparation and characterization of functional material based on hybrid polymer composites

    NASA Astrophysics Data System (ADS)

    Agusu, La; Amiruddin; Taswito, Chen Chen; Herdianto; Zamrun, Muh.

    2016-08-01

    The microstructures and properties of hybrid polymer composites based on polyaniline (PANi)/γ-Fe2O3 nanoparticles/TiO2/carbon have been investigated for multifunctional applications such as heavy metal removal and initial study for radar absorbing material application. γ-Fe2O3 nanoparticles with spherical shape were synthetized by a coprecipitation method from iron sand. By activating the polyethylene glycol (PEG-400) coated carbon of coconut shell, the homogenous shape and size of carbon was achieved. Then, γ- Fe2O3, TiO2, and carbon were mixed with PANi by an in situ polymerization method at low temperature 0-5 oC. Characterization process involved XRD, SEM, FTIR, VSM, and DC conductivity measurements. For radar absorber application, the functionalized polymer composites showed good electrical conductivity 0.45 S/cm to absorb the incoming electromagnetic energy. An efficient and effective reduction of Pb2+ ion from the water has been achieved by using this material.

  7. [Preparation and characterization of core-shell structural magnetic molecularly imprinted polymers for nafcillin].

    PubMed

    Chen, Langxing; Liu, Yuxing; He, Xiwen; Zhang, Yukui

    2015-05-01

    The uniform core-shell nanostructured magnetic molecularly imprinted polymers (MIPs) were synthesized using antibiotic nafcillin as a template. In this protocol, the magnetite nanoparticles (NPs) were synthesized by the solvothermal reaction firstly. Subsequently, the vinyl groups were grated onto silica-modified Fe3O4 surface by 3-methacryloyloxypropyltrimethoxysilane via sol-gel method. Finally, the nafcillin-MIPs film was formed on the surface of Fe3O4 @ SiO2 by the copolymerization of vinyl end group with functional monomer, methacrylic acid, cross-linking agent, ethylene glycol dimethacrylate, the initiator azo-bis-isobutyronitrile and template molecule. The morphological and magnetic characteristics of the MIPs were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and vibrating sample magnetometer. The obtained spherical magnetic MIPs with diameters of about 320 nm had good monodispersity. The static binding experiment was carried out to evaluate the properties of magnetic MIPs and non imprinted polymers (NIPs). The results demonstrated that the magnetic MIPs had high adsorption capacity to template and good selectivity. The imprinting factor and the maximum adsorption capacity of Fe3O4 @ MIPs to nafcillin were 2.46 and 50.7 mg/g, respectively. It is expected that the prepared magnetic MIPs could be used for the enrichment of nafcillin in complex samples.

  8. Characterization, catalyzed water oxidation and anticancer activities of a NIR BODIPY-Mn polymer

    NASA Astrophysics Data System (ADS)

    Lan, Ya-Quan; Xiao, Ke-Jing; Wu, Yun-Jie; Chen, Qiu-Yun

    2017-04-01

    To obtain near-IR absorbing biomaterials as fluorescence cellular imaging and anticancer agents for hypoxic cancer cell, a nano NIR fluorescence Mn(III/IV) polymer (PMnD) was spectroscopically characterized. The PMnD shows strong emission at 661 nm when excited with 643 nm. Furthermore, PMnD can catalyze water oxidation to generate dioxygen when irradiated by red LED light (10 W). In particular, the PMnD can enter into HepG-2 cells and mitochondria. Both anticancer activity and the inhibition of the expression of HIF-1α for PMnD were concentration dependent. Our results demonstrate that PMnD can be developed as mitochondria targeted imaging agents and new inhibitors for HIF-1 in hypoxic cancer cells.

  9. Interferometric pump-probe characterization of the nonlocal response of optically transparent ion implanted polymers

    NASA Astrophysics Data System (ADS)

    Stefanov, Ivan L.; Hadjichristov, Georgi B.

    2012-03-01

    Optical interferometric technique is applied to characterize the nonlocal response of optically transparent ion implanted polymers. The thermal nonlinearity of the ion-modified material in the near-surface region is induced by continuous wave (cw) laser irradiation at a relatively low intensity. The interferometry approach is demonstrated for a subsurface layer of a thickness of about 100 nm formed in bulk polymethylmethacrylate (PMMA) by implantation with silicon ions at an energy of 50 keV and fluence in the range 1014-1017 cm-2. The laser-induced thermooptic effect in this layer is finely probed by interferometric imaging. The interference phase distribution in the plane of the ion implanted layer is indicative for the thermal nonlinearity of the near-surface region of ion implanted optically transparent polymeric materials.

  10. Optimization of a planar all-polymer transistor for characterization of barrier tissue.

    PubMed

    Ramuz, Marc; Margita, Kaleigh; Hama, Adel; Leleux, Pierre; Rivnay, Jonathan; Bazin, Ingrid; Owens, Róisín M

    2015-04-27

    The organic electrochemical transistor (OECT) is a unique device that shows great promise for sensing in biomedical applications such as monitoring of the integrity of epithelial tissue. It is a label-free sensor that is amenable to low-cost production by roll-to-roll or other printing technologies. Herein, the optimization of a planar OECT for the characterization of barrier tissue is presented. Evaluation of surface coating, gate biocompatibility and performance, and optimization of the geometry of the transistor are highlighted. The conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), which is used as the active material in the transistor, has the added advantage of allowing significant light transmission compared to traditional electrode materials and thus permits high-quality optical microscopy. The combination of optical and electronic monitoring of cells shown herein provides the opportunity to couple two very complementary techniques to yield a low-cost method for in vitro cell sensing.

  11. Photopolymerisation and characterization of maleylatedcellulose-g-poly(acrylic acid) superabsorbent polymer.

    PubMed

    Sawut, Amatjan; Yimit, Mamatjan; Sun, Wanfu; Nurulla, Ismayil

    2014-01-30

    A novel biodegradable superabsorbent polymer has been prepared from maleylated cotton stalk cellulose (MCSC) crosslinker and acrylic acid (AA) by ultraviolet (UV) photopolymerization in aqueous solution at room temperature, and irgacure 651 as a photoinitiator. The resulting superabsorbent was characterized by FT-IR, (1)H NMR, SEM and TGA. The effects of preparation conditions such as degree of substitution (DS), amount of maleylated cotton stalk cellulose, exposed time, photoinitiator amount and monomer concentration on the water absorbency and the monomer conversion in graft were evaluated. The swelling kinetics, salt-resistance, water retention capacity and biodegradability of the MCSC-g-PAA superabsorbent were investigated. It was found that, the obtained superabsorbent have good swelling degree that greatly affected by its composition and preparation conditions. Owing to its considerable good water retention capacity, being economical and environment-friendly, it might be useful for its application in agriculture field.

  12. Linear alkaline earth metal phosphinate coordination polymers: synthesis and structural characterization.

    PubMed

    Rood, Jeffrey A; Huttenstine, Ashley L; Schmidt, Zachery A; White, Michael R; Oliver, Allen G

    2014-06-01

    Reaction of alkaline earth metal salts with diphenylphosphinic acid in dimethylformamide solvent afforded four coordination polymers: [Mg3(O2PPh2)6(DMF)2]·2DMF (I), [Ca(O2PPh2)2(DMF)2] (II), [Sr(O2PPh2)2(DMF)2] (III) and [Ba(O2PPh2)2(DMF)2] (IV) (where DMF is N,N-dimethylformamide). Single-crystal X-ray diffraction revealed that all four compounds produce linear chain structures in the solid state, with the Ca, Sr and Ba forming isostructural crystals. The bulk materials were characterized by FT-IR and (1)H NMR spectroscopy and elemental analyses.

  13. Fabrication and Characterization of Cylindrical Light Diffusers Comprised of Shape Memory Polymer

    SciTech Connect

    Small IV, W; Buckley, P R; Wilson, T S; Loge, J M; Maitland, K D; Maitland, D J

    2007-01-29

    We have developed a technique for constructing light diffusing devices comprised of a flexible shape memory polymer (SMP) cylindrical diffuser attached to the tip of an optical fiber. Devices were fabricated by casting an SMP rod over the cleaved tip of an optical fiber and media blasting the SMP rod to create a light diffusing surface. The axial and polar emission profiles and circumferential (azimuthal) uniformity were characterized for various blasting pressures, nozzle-to-sample distances, and nozzle translation speeds. The diffusers were generally strongly forward-directed and consistently withstood over 8 W of incident infrared laser light without suffering damage when immersed in water. These devices are suitable for various endoluminal and interstitial biomedical applications.

  14. Low-velocity impact damage characterization of carbon fiber reinforced polymer (CFRP) using infrared thermography

    NASA Astrophysics Data System (ADS)

    Li, Yin; Zhang, Wei; Yang, Zheng-wei; Zhang, Jin-yu; Tao, Sheng-jie

    2016-05-01

    Carbon fiber reinforced polymer (CFRP) after low-velocity impact is detected using infrared thermography, and different damages in the impacted composites are analyzed in the thermal maps. The thermal conductivity under pulse stimulation, frictional heating and thermal conductivity under ultrasonic stimulation of CFRP containing low-velocity impact damage are simulated using numerical simulation method. Then, the specimens successively exposed to the low-velocity impact are respectively detected using the pulse infrared thermography and ultrasonic infrared thermography. Through the numerical simulation and experimental investigation, the results obtained show that the combination of the above two detection methods can greatly improve the capability for detecting and evaluating the impact damage in CFRP. Different damages correspond to different infrared thermal images. The delamination damage, matrix cracking and fiber breakage are characterized as the block-shape hot spot, line-shape hot spot, and

  15. Improved electrochemical in-situ characterization of polymer electrolyte membrane fuel cell stacks

    NASA Astrophysics Data System (ADS)

    Hartung, I.; Kirsch, S.; Zihrul, P.; Müller, O.; von Unwerth, T.

    2016-03-01

    In-situ diagnostics for single polymer electrolyte membrane fuel cells are well known and established. Comparable stack level techniques are urgently needed to enhance the understanding of degradation during real system operation, but have not yet reached a similar level of sophistication. We have therefore developed a new method for the quantification of the hydrogen crossover current in stacks, which in combination with a previously published technique now allows a clear quantitative characterization of the individual cells' membranes and electrodes. The limits of the reported methods are theoretically assessed and application is then demonstrated on automotive short stacks. The results prove to be highly reproducible and are validated for individual cells of the respective stacks by direct comparison with cyclic voltammetry results, showing good quantitative agreement for the hydrogen crossover current, the double layer capacitance and the electrochemically active surface area.

  16. Solid state NMR and IR characterization of wood polymer structure in relation to tree provenance.

    PubMed

    Santoni, Ilaria; Callone, Emanuela; Sandak, Anna; Sandak, Jakub; Dirè, Sandra

    2015-03-06

    (13)C nuclear magnetic resonance and mid-infrared spectroscopies were used for characterizing changes in the chemical structure of wood polymers (cellulose, hemicellulose and lignin) in relation to the tree growth location. Samples of three provenances in Europe (Finland, Poland and Italy) were selected for studies. The requirement was to use untreated solid wood samples to minimize any manipulation to the nanostructure of native wood. The results confirm that the chemical and physical properties of samples belonging to the same wood species (Picea abies Karst.) differ due to the origin. Both FT-IR and dynamic NMR spectroscopies were able to correctly discriminate samples originating from three different provenances in Europe. Such methods might be very useful for both, research and understanding of wood microstructure and its variability due to the growth conditions.

  17. Characterization of polymer silver pastes for screen printed flexible RFID antennas

    NASA Astrophysics Data System (ADS)

    Janeczek, Kamil; Jakubowska, Małgorzata; Futera, Konrad; MłoŻniak, Anna; Kozioł, GraŻyna; Araźna, Aneta

    Radio Frequency Identification (RFID) systems have become more and more popular in the last few years because of their wide application fields, such as supply chain management and logistics. To continue their development further investigations of new conductive materials for fabrication of RFID transponders' antennas are necessary to be carried out. These materials should provide high flexibility and good radiation performance of printed antennas. In this paper, two polymer silver pastes based on silver flakes were characterized with regard to manufacturing of flexible RFID antennas with screen printing technique. Foil and paper were used as a substrate materials. Surface profile of the printed antennas was measured using an optical profilometer and their resistance was measured with a four-point-probe method. Antenna flexibility was evaluated in cyclic bending tests and its performance with reflection coefficient measurements with the use of differential probe connected to a vector network analyzer. In addition, a maximum read distance of a fabricated RFID transponder was measured.

  18. SAXS Combined with UV-vis Spectroscopy and QELS: Accurate Characterization of Silver Sols Synthesized in Polymer Matrices.

    PubMed

    Bulavin, Leonid; Kutsevol, Nataliya; Chumachenko, Vasyl; Soloviov, Dmytro; Kuklin, Alexander; Marynin, Andrii

    2016-12-01

    The present work demonstrates a validation of small-angle X-ray scattering (SAXS) combining with ultra violet and visible (UV-vis) spectroscopy and quasi-elastic light scattering (QELS) analysis for characterization of silver sols synthesized in polymer matrices. Polymer matrix internal structure and polymer chemical nature actually controlled the sol size characteristics. It was shown that for precise analysis of nanoparticle size distribution these techniques should be used simultaneously. All applied methods were in good agreement for the characterization of size distribution of small particles (less than 60 nm) in the sols. Some deviations of the theoretical curves from the experimental ones were observed. The most probable cause is that nanoparticles were not entirely spherical in form.

  19. Synthesis and Characterization of Conjugated Polymers and Small Molecules for Organic Photovoltaic Devices

    NASA Astrophysics Data System (ADS)

    Kwon, Obum

    Solar energy harvested directly from sunlight using photovoltaic (PV) technology has become one of the most promising ways to meet growing global energy needs with a sustainable resource while minimizing environmental concerns. Especially, organic bulk heterojunction (BHJ) solar cells have been attracting a great deal of interest as a source of renewable energy because of their potential as low-cost, flexible, light-weight and large-scale devices. The choice of materials in a BHJ solar cell is very important for device performance because the power conversion efficiencies (PCEs) are determined by their some crucial characteristics such as energy levels, charge transfer mobilities and structural orders. In this dissertation, two carbazole-diketopyrrolopyrrole based conjugated polymers (P1 and P2) and three thieno-[3,4-c]pyrrole-4,6-dione (TPD) based small molecules (M1, SM1 and SM2) were synthesized and characterized to investigate their optical, electrical and photovoltaic properties. First, the substitution of alkyl and aryl side chains on the carbazole moiety of two push-pull conjugated polymers (P1 and P2) shows the significant differences in the optical, electrical and photovoltaic properties. Second, TPD-based conjugated small molecule with a donor-acceptor-donor-acceptor-donor (D-A-D-A-D) framework, M1 shows the relatively deep HOMO level resulting the relatively high Voc.(0.85 eV) Small molecule BHJ solar cells were fabricated and characterized using different M1:PC71BM blend ratios, solvents, and additives and the highest PCE achieved in this study was 1.86%. Lastly, different bridgehead atoms of SM1 and SM2 can affect their energy band levels and device performances. The PCE (2.5%) of the SM2-based SM-BHJ solar cell was higher than that of the SM1-based SM-BHJ solar cell (1.5%).

  20. LC–MS/MS quantification of a neuropeptide fragment kisspeptin-10 (NSC 741805) and characterization of its decomposition product and pharmacokinetics in rats

    PubMed Central

    Liu, Zhongfa; Ren, Chen; Jones, William; Chen, Ping; Seminara, Stephanie B.; Chan, Yee-Ming; Smith, Nicola F.; Covey, Joseph M.; Wang, Jeffrey; Chan, Kenneth K.

    2014-01-01

    The kisspeptins are critical regulators of mammalian reproduction. Kisspeptin-10 (45YNWNSFGLRF-NH254, kisspeptin-112–121 or metastin 45–54, NSC 741805), an active fragment of kisspeptin, has been shown to be a potent stimulator of gonadotropin-releasing hormone and secretion of luteinizing hormone in both rodents and primates. This shorter peptide fragment may have clinical utility potential and it is important to characterize its pharmacokinetic property. Recently, the pharmacokinetics of both kisspeptin-54 and kisspeptin-10 were characterized in humans using a radioimmunoassay (RIA), which measures only the immunoreactive kisspeptin (kisspeptin-IR). In this study, a highly sensitive and specific LC–MS/MS assay was developed to quantify kisspeptin-10 levels in rat plasma. The lower limit of quantitation (LLOQ) was 0.5 ng/mL, the within-day and between-day coefficient of variations (CVs) ranged from 5.2 to 15.4% and 1.3 to 14.2%, and the accuracy values ranged from 98 to 114% and 99 to 105%, respectively. With this method, stability studies demonstrated that kisspeptin-10 degraded rapidly with decomposition half-lives of 6.8 min, 2.9 min and 1.7 min at 4 °C, 25 °C, and 37 °C, respectively. The principal decomposition product was characterized as the N-terminal tyrosine deleted kisspeptin-10 46NWDSFGLRF-NH254. Pharmacokinetic study in rats showed that low ng/mL kisspeptin-10 was detected in the first few minutes, and eliminated rapidly and became undetectable 30 min after intravenous (i.v.) bolus administration of 1.0 mg/kg kisspeptin-10. PMID:23524040

  1. Production and analysis of thermal decomposition products from polymeric materials

    NASA Technical Reports Server (NTRS)

    Chatfield, D. A.; Einhorn, I. N.; Hileman, F. D.; Futrell, J. H.; Voorhees, K. J.

    1978-01-01

    A description is presented of a strategy for analyzing the combustion process and the degradation products which are formed. One of three primary objectives in the study of polymer degradation is related to the characterization of the material to be studied and the investigation of the thermal behavior of the material. Another objective is concerned with the definition of the nature of the decomposition process by identification and quantitation of the degradation products. The third objective involves the determination of the mechanism and kinetics of the decomposition process. The methods of sample degradation include pyrolysis, oxidative degradation, flaming combustion, and the use of large-scale combustion chambers. Methods of chemical separation and identification are considered, taking into account low-boiling volatiles, high-boiling volatiles, and ancillary techniques.

  2. Structural/surface characterization and catalytic evaluation of rare-earth (Y, Sm and La) doped ceria composite oxides for CH3SH catalytic decomposition

    NASA Astrophysics Data System (ADS)

    He, Dedong; Chen, Dingkai; Hao, Husheng; Yu, Jie; Liu, Jiangping; Lu, Jichang; Liu, Feng; Wan, Gengping; He, Sufang; Luo, Yongming

    2016-12-01

    A series of rare earth (Y, Sm and La) doped ceria composite oxides and pure CeO2 were synthesized and evaluated by conducting CH3SH catalytic decomposition test. Several characterization studies, including XRD, BET, Raman, H2-TPR, XPS, FT-IR, CO2-TPD and CH3SH-TPD, were undertaken to correlate structural and surface properties of the obtained ceria-based catalysts with their catalytic performance for CH3SH decomposition. More oxygen vacancies and increased basic sites exhibited in the rare earth doped ceria catalysts. Y doped ceria sample (Ce0.75Y0.25O2-δ), with a moderate increase in basic sites, contained more oxygen vacancies. More structural defects and active sites could be provided, and a relatively small amount of sulfur would accumulate, which resulted in better catalytic performance. The developed catalyst presented good catalytic behavior with stability very similar to that of typical zeolite-based catalysts reported previously. However, La doped ceria catalyst (Ce0.75La0.25O2-δ) with the highest alkalinity was not the most active one. More sulfur species would be adsorbed and a large amount of cerium sulfide species (Ce2S3) would accumulate, which caused deactivation of the catalysts. The combined effect of increased oxygen vacancies and alkalinity led to the catalytic stability of Ce0.75Sm0.25O2-δ sample was comparable to that of pure CeO2 catalyst.

  3. Synthesis, purification and characterization of multi- and single-wall nanotubes produced by catalytic decomposition of hydrocarbons

    NASA Astrophysics Data System (ADS)

    Colomer, J.-F.; Piedigrosso, P.; Willems, I.; Konya, Z.; Fonseca, A.; Nagy, J. B.

    1999-09-01

    The catalytic process is the third method, with laser evaporation and electric arc techniques, to produce carbon nanotubes. By this way, multi-wall carbon nanotubes can be synthesised by catalytic decomposition of acetylene over supported catalyst Co/Zeolite NaY. The tubes produced are purified in two steps: first, separation of nanotubes and catalyst particles are carried out by fluorhydric acid treatment; then, the amorphous carbon elimination is made following two oxidative treatments. Multi-wall carbon nanotubes are obtained quasi-pure with high yield. Recently, single-walled nanotubes can be also synthesised by the catalytic pyrolysis of hydrocarbons. Typical TEM images of multi- and single-wall carbon nanotubes are given: for multi-wall nanotubes, after each step of production and purification, and for single-wall nanotubes after synthesis.

  4. The ability of the Coincidence Doppler Broadening Spectroscopy to characterize polymers containing different chemical elements

    NASA Astrophysics Data System (ADS)

    Yang, J.; Zhang, T.; Han, L. A.; Cao, X. Z.; Yu, R. S.; Wang, B. Y.

    2017-04-01

    Hydrocarbon polymers, O-containing, F-containing and Cl-containing polymers are comprehensively studied by Coincidence Doppler Broadening Spectroscopy (CDBS). It is shown that for polymers with different chemical structure, CDBS results can effectively distinguish polar groups C dbnd O, Csbnd Cl, and Csbnd F. For polymers with similar chemical structure, the intensity of the element-specific peak in the CDBS ratio curve is dependent not only on the fraction of free positrons, but also on the content of characteristic atom in polymer repeated unit, and the polarity of the polymer molecule. For polymers containing several different polar groups, such as PCTFE (Csbnd F & Csbnd Cl) and PFA (Csbnd F & C dbnd O), whether the element-specific peak appears or not depends on the amount of the polar groups and its positron capture ability. This work may provide insights into potential applications of CDBS for studying complex polymer systems.

  5. Formulation and Characterization of Solid Dispersion Prepared by Hot Melt Mixing: A Fast Screening Approach for Polymer Selection

    PubMed Central

    Enose, Arno A.; Dasan, Priya K.; Sivaramakrishnan, H.; Shah, Sanket M.

    2014-01-01

    Solid dispersion is molecular dispersion of drug in a polymer matrix which leads to improved solubility and hence better bioavailability. Solvent evaporation technique was employed to prepare films of different combinations of polymers, plasticizer, and a modal drug sulindac to narrow down on a few polymer-plasticizer-sulindac combinations. The sulindac-polymer-plasticizer combination that was stable with good film forming properties was processed by hot melt mixing, a technique close to hot melt extrusion, to predict its behavior in a hot melt extrusion process. Hot melt mixing is not a substitute to hot melt extrusion but is an aid in predicting the formation of molecularly dispersed form of a given set of drug-polymer-plasticizer combination in a hot melt extrusion process. The formulations were characterized by advanced techniques like optical microscopy, differential scanning calorimetry, hot stage microscopy, dynamic vapor sorption, and X-ray diffraction. Subsequently, the best drug-polymer-plasticizer combination obtained by hot melt mixing was subjected to hot melt extrusion process to validate the usefulness of hot melt mixing as a predictive tool in hot melt extrusion process. PMID:26556187

  6. Fabrication and Characterization of Conductive Conjugated Polymer-Coated Antheraea mylitta Silk Fibroin Fibers for Biomedical Applications.

    PubMed

    Gh, Darshan; Kong, Dexu; Gautrot, Julien; Vootla, Shyam Kumar

    2017-02-27

    Conductive polymers are interesting materials for a number of biological and medical applications requiring electrical stimulation of cells or tissues. Highly conductive polymers (polypyrrole and polyaniline)/Antheraea mylitta silk fibroin coated fibers are fabricated successfully by in situ polymerization without any modification of the native silk fibroin. Coated fibers characterized by scanning electron microscopy confirm the silk fiber surface is covered by conductive polymers. Thermogravimetric analysis reveals preserved thermal stability of silk fiber after coating process. X-ray diffraction of degummed fiber diffraction peaks at around 2θ = 20.4 and 16.5 confirms the preservation of the β-sheet structure typical of degummed silk II fibers. This phenomenon implies that both polypyrrole and polyaniline chains form interactions with peptide linkages in degummed fiber macromolecules, without significantly disrupting protein assembly. Fourier transform infrared spectroscopy of coated fibers indicates hydrogen bonding and electrostatic interactions exist between silk fibroin macromolecules and conductive polymers. Resulting fibers display good conductive properties compared to corresponding conjugated polymers. In vitro analysis (live/dead assay) of the behavior of human immortalized keratinocytes (HaCaTs) on coated fibers demonstrates improved cell-adhesive properties and viability after polymers coating. Hence, polypyrrole- and polyaniline-coated A. mylitta silk fibers are suitable for application in cell culture and for tissue engineering, where electrical conduction properties are required.

  7. PLLA-HA composites: Synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Gonzalez, Gema; Albano, Carmen; Palacios, Jordana

    2012-07-01

    A composite based on PLLA -HA was prepared by the solvent casting technique and characterized. An interaction between the polymer matrix and HA through the carbonyl and phosphate groups was obtained by FTIR . The several thermal transitions of PLLA were evaluated by DSC: the glass transition, crystallization, cold crystallization, melt-recrystallization and melting. The addition of HA to PLLA matrix increases its glass transition temperature and no major changes on the melting temperature and crystallinity were observed. The PLLA-HA composite showed better thermal stability than the neat polymer. The introduction of the nano-HA particles increased the decomposition temperature and the activation energy retarding the decomposition process.

  8. Synthesis and characterization of ionomers as polymer electrolytes for energy conversion devices

    NASA Astrophysics Data System (ADS)

    Oh, Hyukkeun

    Single-ion conducting electrolytes present a unique alternative to traditional binary salt conductors used in lithium-ion batteries. Secondary lithium batteries are considered as one of the leading candidates to replace the combustible engines in automotive technology, however several roadblocks are present which prevent their widespread commercialization. Power density, energy density and safety properties must be improved in order to enable the current secondary lithium battery technology to compete with existing energy technologies. It has been shown theoretically that single-ion electrolytes can eliminate the salt concentration gradient and polarization loss in the cell that develops in a binary salt system, resulting in substantial improvements in materials utilization for high power and energy densities. While attempts to utilize single-ion conducting electrolytes in lithium-ion battery systems have been made, the low ionic conductivities prevented the successful operation of the battery cells in ambient conditions. This work focuses on designing single-ion conducting electrolytes with high ionic conductivities and electrochemical and mechanical stability which enables the stable charge-discharge performance of battery cells. Perfluorosulfonate ionomers are known to possess exceptionally high ionic conductivities due to the electron-withdrawing effect caused by the C-F bonds which stabilizes the negative charge of the anion, leading to a large number of free mobile cations. The effect of perfluorinated sulfonic acid side chains on transport properties of proton exchange membrane polymers was examinated via a comparison of three ionomers, having different side chain structures and a similar polymer backbone. The three different side chain structures were aryl-, pefluoro alkyl-, and alkyl-sulfonic acid groups, respectively. All ionomers were synthesized and characterized by 1H and 19F NMR. A novel ionomer synthesized with a pendant perfluorinated sulfonic acid

  9. An investigation of adhesive/adherend and fiber/matrix interactions. Part A: Surface characterization of titanium dioxide, titantium and titanium 6% Al to 4% V powders: Interaction with water, hydrogen chloride and polymers

    NASA Technical Reports Server (NTRS)

    Siriwardane, R. V.; Wightman, J. P.

    1982-01-01

    The titanium dioxide surface is discussed. Polymer adhesive are also discussed. Titanium powders are considered. Characterization techniques are also considered. Interactions with polymers, water vapor, and HCl are reported. Adsorbents are characterized.

  10. Tris dithiocarbamate of Co(III) complexes: Synthesis, characterization, thermal decomposition studies and experimental and theoretical studies on their crystal structures

    NASA Astrophysics Data System (ADS)

    Sonia, Ayyavoo Sait; Bhaskaran, Ramalingam

    2017-04-01

    New homoleptic complexes of the form [Co(L1)3] & [Co(L2)3] where L1 = (ethylaminoethanol dithiocarbamate) 1 and L2 = (methylaminoethanol dithiocarbamate) 2 have been prepared and characterized by elemental analysis, IR, UV-visible absorption spectra, Cyclic voltammetry,1H and C13 NMR. The thermal properties were studied using a simultaneous thermal analyzer, and showed two main steps of decomposition. In addition, structures for 1 and 2 have been elucidated by X-ray crystallography. The single-crystal X-ray analysis for both the complexes showed distorted octahedral geometry. The optimized molecular structure, natural bond orbital analysis, electrostatic potential map, HOMO-LUMO energies, molecular properties, and atomic charges of these molecules have been studied by performing DFT/B3LYP/6-31G(d,p) level of theory in gas phase.

  11. Hyperspectral imaging and characterization of live cells by broadband coherent anti-Stokes Raman scattering (CARS) microscopy with singular value decomposition (SVD) analysis.

    PubMed

    Khmaladze, Alexander; Jasensky, Joshua; Price, Erika; Zhang, Chi; Boughton, Andrew; Han, Xiaofeng; Seeley, Emily; Liu, Xinran; Banaszak Holl, Mark M; Chen, Zhan

    2014-01-01

    Coherent anti-Stokes Raman scattering (CARS) microscopy can be used as a powerful imaging technique to identify chemical compositions of complex samples in biology, biophysics, medicine, and materials science. In this work we developed a CARS microscopic system capable of hyperspectral imaging. By employing an ultrafast laser source, a photonic crystal fiber, and a scanning laser microscope together with spectral detection by a highly sensitive back-illuminated cooled charge-coupled device (CCD) camera, we were able to rapidly acquire and process hyperspectral images of live cells with chemical selectivity. We discuss various aspects of hyperspectral CARS image analysis and demonstrate the use of singular value decomposition methods to characterize the cellular lipid content.

  12. Assembly and Characterization of Well Defined High Molecular Weight Poly(p-phenylene) Polymer Brushes

    SciTech Connect

    Alonzo Calderon, Jose E; Kilbey, II, S Michael; Ankner, John Francis; Britt, Phillip F; Chen, Jihua; Dadmun, Mark D; Deng, Suxiang; Hong, Kunlun; Mays, Jimmy; Messman, Jamie M; Sumpter, Bobby; Swader, Onome A; Yu, Xiang; Bredas, Jean-Luc E; Malagoli, Massimo

    2011-01-01

    The assembly and characterization of well-defined, end-tethered poly(p-phenylene) (PPP) brushes having high molecular weight, low polydispersity and high 1,4-stereoregularity are presented. The PPP brushes are formed using a precursor route that relies on either self-assembly or spin coating of high molecular weight (degrees of polymerizations 54, 146, and 238) end-functionalized poly(1,3-cyclohexadiene) (PCHD) chains from benzene solutions onto silicon or quartz substrates, followed by aromatization of the end-attached PCHD chains on the surface. The approach allows the thickness (grafting density) of the brushes to be easily varied. The dry brushes before and after aromatization are characterized by ellipsometry, atomic force microscopy, grazing angle attenuated total reflectance Fourier transform infrared spectroscopy, and UV-Vis spectroscopy. The properties of the PPP brushes are compared with those of films made using oligo-paraphenylenes and with ab initio density functional theory simulations of optical properties. Our results suggest conversion to fully aromatized, end-tethered PPP polymer brushes having effective conjugation lengths of 5 phenyl units.

  13. Development and characterization of high refractive index and high scattering acrylate polymer layers

    NASA Astrophysics Data System (ADS)

    Eiselt, Thomas; Gomard, Guillaume; Preinfalk, Jan; Gleissner, Uwe; Lemmer, Uli; Hanemann, Thomas

    2016-04-01

    The aim is to develop a polymer layer which has the ability to diffuse light homogeneously and exhibit a high refractive index. The mixtures are containing an acrylate casting resin, benzylmethacrylate, phenanthrene and other additives. Phenanthrene is employed to increase the refractive index. The mixtures are first rheologically characterized and then polymerized with heat and UV radiation. For the refractive index measurements the polymerized samples require a planar surface without air bubbles. To produce flat samples a special construction consisting of a glass plate, a teflon sheet, a silicone ring (PDMS mold), another teflon sheet and another glass plate is developed. Glue clamps are used to fix this construction together. Selected samples have a refractive index of 1.585 at 20°C at a wavelength of 589nm. A master mixture with a high refractive index is taken for further experiments. Nano scaled titanium dioxide is added and dispersed into the master mixture and then spin coated on a glass substrate. These layers are optically characterized. The specular transmission and the overall transmission are measured to investigate the degree of scattering, which is defined as the haze. Most of the presented layers express the expected haze of over 50%.

  14. Nanomechanical and tribological characterization of the MPC phospholipid polymer photografted onto rough polyethylene implants.

    PubMed

    Wang, Na; Trunfio-Sfarghiu, Ana-Maria; Portinha, Daniel; Descartes, Sylvie; Fleury, Etienne; Berthier, Yves; Rieu, Jean-Paul

    2013-08-01

    Grafting biomimetic polymers onto biomaterials such as implants is one of the promising approaches to increase their tribological performance and biocompatibility and to reduce wear. In this paper, poly(2-methacryloyloxyethyl phosphorylcholine) (p(MPC)) brushes were obtained by photografting MPC from the rough surface of ultra high molecular weight polyethylene (UHMWPE) joint implants. Such substrates have a high roughness (Ra∼650nm) which often has the same order of magnitude as the brush thickness, so it is very difficult to estimate the vertical density profile of the grafted content. The quality of the p(MPC) grafting was evaluated through a wide range of characterization techniques to reveal the effectiveness of the grafting: atomic force microcopy (AFM) imaging and force spectroscopy, contact angle, SEM/EDX, and confocal microscopy. After testing the methods on smooth glass substrate as reference, AFM nano-indentation proves to be a reliable non destructive method to characterize the thickness and the mechanical properties of the p(MPC) layer in liquid physiological medium. Tribological measurements using a homemade biotribometer confirm that, despite heterogeneity thickness (h=0.5-6μm), the p(MPC) layer covers the roughness of the UHMWPE substrate and acts as an efficient lubricant with low friction coefficient and no wear for 9h of friction.

  15. Characterization and dynamic modeling of ionic polymer-metal composites (IPMC): artificial muscles

    NASA Astrophysics Data System (ADS)

    Mudigonda, Ashwin; Zhu, Jianchao J.

    2006-03-01

    This paper deals with the characterization and dynamic modeling of the behavior of two types of the Ionic Polymer Metal Composite (IPMC) "artificial muscle" materials. Environmental Robots, Inc. (ERI) was the initial vendor and its IPMC products required hydration for optimal performance. Virginia Polytechnic Institute and State University (Virginia Tech, VT) subsequently developed their innovative ionic solvent filled IPMCs that obviated hydration. Static tests were conducted to characterize force, displacement and current as a function of applied voltage. Dynamic tests were conducted to observe the frequency response of the material. Fatigue tests were performed on the ERI IPMCs to observe the change in behavior over time. It was found that the VT IPMCs had a bandwidth that was almost half that of the ERI product. However, the obviation of hydration of the VT's IPMC ensured the repeatability of performance and generated increased force densities. A feasibility study is presented to estimate the amount of IPMC materials and power consumption for a biceps exo-muscular assistance device based on the characteristics of the current IPMC materials and a primitive exo-muscular fiber bundle structure.

  16. Use of Fourier transform infrared spectrometry to characterize composites and polymers

    SciTech Connect

    Lerner, B.D.

    1992-01-01

    Carbon fiber reinforced composites (CFRCs) combine the high tensile strength of carbon fibers with a highly crosslinked polymer matrix. Typically the carbon fibers are in the form of a cloth which is preimpregnated with a mixture of either unreacted monomers or partially reacted oligomers that are polymerized at high temperatures and pressures. For the product to have the desired mechanical properties, the prepreg must undergo the expected crosslinking reaction and this process is susceptible to small changes in the composition of the reactants that can occur on atmospheric exposure. In this dissertation the use of diffuse reflectance Fourier transform infrared (FT-IR) spectrometry as a means of characterizing small compositional changes occurring in epoxy and polyimide prepregs was evaluated. Prepregs were aged under similar conditions of temperature and humidity. Several methods of analyzing the spectra were investigated, ranging from the simple measurement of the ratio of two bands in the spectra to the combined use of Fourier self-deconvolution (FSD) and curve-fitting. Useful data on the epoxy polymers was obtained using each of these techniques, with the most linear plots of the spectral changes with time being obtained using combined FSD and curve-fitting. The development of several different types of step-scanning FT-IR spectrometers is described. Installation of a piezoelectric transducer (PZT) behind the movable mirror of the interferometer allows positional control to an accuracy of [+-]1.5 nm. Three coarse positioning drives, based on a dc motor, an Inchworm PZT drive, and a microstepper motor, were evaluated. Each permitted the desired level of positional accuracy, but none permitted the optical element to be stepped to the next sampling point in less than 0.5 s. The use of Fourier transforms to demodulate the sinusoidal signal from a phase-modulated interferogram was demonstrated.

  17. Characterization of Peptide Polymer Interactions in Poly(alkylcyanoacrylate) Nanoparticles: A Mass Spectrometric Approach.

    PubMed

    Kafka, Alexandra P; Kleffmann, Torsten; Rades, Thomas; McDowell, Arlene

    2010-07-01

    Drug/polymer interactions occur during in situ polymerization of poly(alkylcyanoacrylate) (PACA) formulations. We have used MALDI ionization coupled tandem time-of-flight (TOF) mass spectrometry as an accurate method to characterize covalent peptide/polymer interactions of PACA nanoparticles with the bioactives D-Lys6-GnRH, insulin, [Asn1-Val5]-angiotensin II, and fragments of insulin-like growth factor 1 (IGF-1 (1-3)) and human adrenocorticotropic hormone (h-ACTH, (18-39)) at the molecular level. Covalent interactions of peptide with alkylcyanoacrylate were identified for D-Lys6-GnRH, [Asn1-Val5]-angiotensin II and IGF-1 (1-3). D-Lys6-GnRH and [Asn1-Val5]-angiotensin II were modified at their histidine side chain within the peptide, whilst IGF-1 (1-3) was modified at the C-terminal glutamic acid residue. The more complex protein insulin was not modified despite the presence of 2 histidine residues. This might be explained by the engagement of histidine residues in the folding and sterical arrangement of insulin under polymerization conditions. As expected, h-ACTH (18-39) that does not contain histidine residues did not interfere in the polymerization process. Lowering the pH did not prevent the covalent association of PACA with D-Lys6-GnRH or IGF-1 (1-3). Conclusively, protein and peptide bioactives are potentially reactive towards alkylcyanoacrylate monomers via various mechanisms with limited interference of pH. Histidines and C-terminal glutamic acid residues have been identified as potential sites of interaction. The likelihood of their engagement in the polymerization process (initiators), however, seems dependent on their sterical availability. The reactivity of nucleophilic functional groups should always be considered and bioactives examined for their potential to covalently interfere with alkylcyanoacrylate monomers, especially when designing PACA delivery systems for protein and peptide biopharmaceuticals.

  18. Characterization of Peptide Polymer Interactions in Poly(alkylcyanoacrylate) Nanoparticles: A Mass Spectrometric Approach.

    PubMed

    Kafka, Alexandra P; Kleffmann, Torsten; Rades, Thomas; McDowell, Arlene

    2010-02-17

    Drug/polymer interactions occur during in situ polymerization of poly(alkylcyanoacrylate) (PACA) formulations. We have used MALDI ionization coupled tandem time-of-flight (TOF) mass spectrometry as an accurate method to characterize covalent peptide/polymer interactions of PACA nanoparticles with the bioactives D-Lys6-GnRH, insulin, [Asn1-Val5]-angiotensin II, and fragments of insulin-like growth factor 1 (IGF-1 (1-3)) and human adrenocorticotropic hormone (h-ACTH, (18-39)) at the molecular level. Covalent interactions of peptide with alkylcyanoacrylate were identified for D-Lys6-GnRH, [Asn1-Val5]-angiotensin II and IGF-1 (1-3). D-Lys6-GnRH and [Asn1-Val5]-angiotensin II were modified at their histidine side chain within the peptide, whilst IGF-1 (1-3) was modified at the C-terminal glutamic acid residue. The more complex protein insulin was not modified despite the presence of 2 histidine residues. This might be explained by the engagement of histidine residues in the folding and sterical arrangement of insulin under polymerization conditions. As expected, h-ACTH (18-39) that does not contain histidine residues did not interfere in the polymerisation process. Lowering the pH did not prevent the covalent association of PACA with D-Lys6-GnRH or IGF-1 (1-3). Conclusively, protein and peptide bioactives are potentially reactive towards alkylcyanoacrylate monomers via various mechanisms with limited interference of pH. Histidines and C-terminal glutamic acid residues have been identified as potential sites of interaction. The likelihood of their engagement in the polymerisation process (initiators), however, seems dependant on their sterical availability. The reactivity of nucleophilic functional groups should always be considered and bioactives examined for their potential to covalently interfere with alkylcyanoacrylate monomers, especially when designing PACA delivery systems for protein and peptide biopharmaceuticals.

  19. Development and characterization of new 157-nm photoresists based on advanced fluorinated polymers

    NASA Astrophysics Data System (ADS)

    Yamazaki, Tamio; Furukawa, Takamitsu; Itani, Toshiro; Ishikawa, Takuji; Koh, Meiten; Araki, Takayuki; Toriumi, Minoru; Kodani, T.; Aoyama, Hirokazu; Yamashita, Tsuneo

    2003-06-01

    Fluorinated polymers show a good transparency at the 157-nm exposure wavelength for single-layer resists. We have developed fluorinated resist polymers for 157-nm lithography. These polymers are main-chain fluorinated polymers synthesized by the co-polymerization of tetrafluoroethylene (TFE) and polymers such as poly(TFE/norbornene/α-fluoroolefin) fluoropolymers (FP1). In this paper, a number of polymerization initiators were evaluated in the polymerization of PF1-type polymers in order to investigate the effect of polymer end groups on optical and dissolution properties. We found that the polymer end group greatly affects the dissolution properties of these polymers when using a standard 0.26N tetramethylammonium hydroxide (TMAH) aqueous developer solution. These end groups also affect the polymer transparencies at 157-nm, and the resulting lithographic performance. The fluorocarbon initiator named "F2" induced the lowered absorbance (~0.4μm-1) and an increase in the dissolution rate (~300 nm/sec) without noticeable amounts of swelling. These polymer-based resists can achieve a resolution of less than 60-nm using a 157-nm laser microstepper (NA=0.85) with a Levenson-type strong phase shifting mask.

  20. Functionalized white graphene - Copper oxide nanocomposite: Synthesis, characterization and application as catalyst for thermal decomposition of ammonium perchlorate.

    PubMed

    Paulose, Sanoop; Raghavan, Rajeev; George, Benny K

    2017-05-15

    Reactivity is of great importance for metal oxide nanoparticles (MONP) used as catalysts and advanced materials, but seeking for higher reactivity seems to be conflict with high chemical stability required for MONP. There is direct balance between reactivity and stability of these MONP. This could be acheived for metal oxide by dispersing them in a substrate. Here, we report a simple, efficient and high-yield process for the production of copper oxide (CuO) nanoparticles dispersed on a chemically inert material, few-layer hexagonal boron nitride (h-BN) with a thickness around 1.7nm and lateral dimensions mostly below 200nm. The mechano-chemical reaction which take place at atmospheric pressure and room temperature involves a urea assisted exfoliation of pristine boron nitride. Copper oxide nanoparticles dispersed on the surface of these few layered h-BN reduced its tendency for aggregation. The optimum concentration of CuO:h-BN was found to be 2:1 which shows highest catalytic activity for the thermal decomposition of ammonium perchlorate. The high catalytic activity of the in situ synthesized CuO-h-BN composite may be attributed to uniform distribution of CuO nanoparticles on the few layered h-BN which in turn provide a number of active sites on the surface due to non aggregation.

  1. Structural characterization of irreversibly adsorbed polymer layers at the polymer/solid interface - In-situ grazing incidence angle x-ray scattering studies

    NASA Astrophysics Data System (ADS)

    Jiang, Naisheng; Chen, Fen; Chen, Xiameng; Han, Zexi; Liang, Chen; Gin, Peter; Asada, Mitsunori; Endoh, Maya; Koga, Tad

    2012-02-01

    In recent years, great attention has been paid to irreversibly adsorbed polymer layers formed on solid substrates since they can modify various properties of polymeric materials confined at the nanometer scale. In this talk, by the combined use of in-situ grazing incidence small angle x-ray scattering and x-ray reflectivity techniques, we aim to characterize the detailed structures of the adsorbed layers composed of different homopolymers (polystyrene, polybutadiene, poly (ethylene oxide), and poly (methyl methacrylate)) prepared on silicon substrates. We will highlight the generality/differences in the structures, leading to a better understanding of the formation process of the adsorbed layers at the impenetrable solid interfaces.

  2. Fundamental Vibration Frequency and Damping Estimation: A Comparison Using the Random Decrement Method, the Empirical Mode Decomposition, and the HV Spectral Ratio Method for Local Site Characterization

    NASA Astrophysics Data System (ADS)

    Huerta-Lopez, C. I.; Upegui Botero, F. M.; Pulliam, J.; Willemann, R. J.; Pasyanos, M.; Schmitz, M.; Rojas Mercedes, N.; Louie, J. N.; Moschetti, M. P.; Martinez-Cruzado, J. A.; Suárez, L.; Huerfano Moreno, V.; Polanco, E.

    2013-12-01

    Site characterization in civil engineering demands to know at least two of the dynamic properties of soil systems, which are: (i) dominant vibration frequency, and (ii) damping. As part of an effort to develop understanding of the principles of earthquake hazard analysis, particularly site characterization techniques using non invasive/non destructive seismic methods, a workshop (Pan-American Advanced Studies Institute: New Frontiers in Geophysical Research: Bringing New Tools and Techniques to Bear on Earthquake Hazard Analysis and Mitigation) was conducted during july 15-25, 2013 in Santo Domingo, Dominican Republic by the alliance of Pan-American Advanced Studies Institute (PASI) and Incorporated Research Institutions for Seismology (IRIS), jointly supported by Department of Energy (DOE) and National Science Foundation (NSF). Preliminary results of the site characterization in terms of fundamental vibration frequency and damping are here presented from data collected during the workshop. Three different methods were used in such estimations and later compared in order to identify the stability of estimations as well as the advantage or disadvantage among these methodologies. The used methods were the: (i) Random Decrement Method (RDM), to estimate fundamental vibration frequency and damping simultaneously; (ii) Empirical Mode Decomposition (EMD), to estimate the vibration modes, and (iii) Horizontal to Vertical Spectra ratio (HVSR), to estimate the fundamental vibration frequency. In all cases ambient vibration and induced vibration were used.

  3. Materials and characterization techniques for high-temperature polymer electrolyte membrane fuel cells

    PubMed Central

    2015-01-01

    Summary The performance of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFC) is critically dependent on the selection of materials and optimization of individual components. A conventional high-temperature membrane electrode assembly (HT-MEA) primarily consists of a polybenzimidazole (PBI)-type membrane containing phosphoric acid and two gas diffusion electrodes (GDE), the anode and the cathode, attached to the two surfaces of the membrane. This review article provides a survey on the materials implemented in state-of-the-art HT-MEAs. These materials must meet extremely demanding requirements because of the severe operating conditions of HT-PEMFCs. They need to be electrochemically and thermally stable in highly acidic environment. The polymer membranes should exhibit high proton conductivity in low-hydration and even anhydrous states. Of special concern for phosphoric-acid-doped PBI-type membranes is the acid loss and management during operation. The slow oxygen reduction reaction in HT-PEMFCs remains a challenge. Phosphoric acid tends to adsorb onto the surface of the platinum catalyst and therefore hampers the reaction kinetics. Additionally, the binder material plays a key role in regulating the hydrophobicity and hydrophilicity of the catalyst layer. Subsequently, the binder controls the electrode–membrane interface that establishes the triple phase boundary between proton conductive electrolyte, electron conductive catalyst, and reactant gases. Moreover, the elevated operating temperatures promote carbon corrosion and therefore degrade the integrity of the catalyst support. These are only some examples how materials properties affect the stability and performance of HT-PEMFCs. For this reason, materials characterization techniques for HT-PEMFCs, either in situ or ex situ, are highly beneficial. Significant progress has recently been made in this field, which enables us to gain a better understanding of underlying processes occurring during

  4. Characterizing the Material Properties of Polymer-Based Microelectrode Arrays for Retinal Prosthesis

    SciTech Connect

    Park, Christina Soyeun

    2003-06-01

    The Retinal Prosthesis project is a three year project conducted in part at the Lawrence Livermore National Laboratory and funded by the Department of Energy to create an epiretinal microelectrode array for stimulating retinal cells. The implant must be flexible to conform to the retina, robust to sustain handling during fabrication and implantation, and biocompatible to withstand physiological conditions within the eye. Using poly(dimethyl siloxane) (PDMS), LLNL aims to use microfabrication techniques to increase the number of electrodes and integrate electronics. After the initial designs were fabricated and tested in acute implantation, it became obvious that there was a need to characterize and understand the mechanical and electrical properties of these new structures. This knowledge would be imperative in gaining credibility for polymer microfabrication and optimizing the designs. Thin composite microfabricated devices are challenging to characterize because they are difficult to handle, and exhibit non-linear, viscoelastic, and anisotropic properties. The objective of this research is to device experiments and protocols, develop an analytical model to represent the composite behavior, design and fabricate test structures, and conduct experimental testing to determine the mechanical and electrical properties of PDMS-metal composites. Previous uniaxial stretch tests show an average of 7% strain before failure on resistive heaters of similar dimensions deposited on PDMS. Lack of background information and questionable human accuracy demands a more sophisticated and thorough testing method. An Instron tensile testing machine was set up to interface with a digital multiplexor and computer interface to simultaneously record and graph position, load, and resistance across devices. With a compliant load cell for testing polymers and electrical interconnect grips designed and fabricated to interface the sample to the electronics, real-time resistance measurements

  5. Covalently functionalized noble metal nanoparticles for molecular imprinted polymer biosensors: Synthesis, characterization, and SERS detection

    NASA Astrophysics Data System (ADS)

    Volkert, Anna Allyse

    This dissertation evaluates how gold nanoparticle structure and local environment influence resulting sensor function when using these nanomaterials for complex sample analysis. Molecular imprinted polymers (MIPs), a class of plastic antibodies, are engineered and incorporated into these nanosensors thereby facilitating the quantitative detection of a variety of small molecules when Raman spectroscopy and surface enhanced Raman scattering (SERS) are used for detection. First, homogeneous seeded growth gold nanosphere synthesis is evaluated as a function of ionic double layer composition and thickness. Systematically increasing the citrate concentration during synthesis improves nanomaterial shape homogeneity; however, further elevations of citrate concentration increase the number of internal and/or external atomic defects in the nanomaterials which leads to decreasing solution-phase stability. Next, spherical gold nanoparticles are modified with self-assembled monolayer (SAM), modeled using interfacial energy calculations, and experimental characterized using transmission electron microscopy, NMR, extinction spectroscopy, zeta potential, X-ray photoelectron spectroscopy, and flocculation studies to assess the morphology, surface chemistry, optical properties, surface charge, SAM packing density, and nanoparticle stability, respectively. The number of molecules on the nanostructures increases with increasing ionic strength (by decreasing the electrostatic interfacial energy between assembled molecules) which subsequently promotes nanoparticle stability. Third, plastic antibodies that recognize three drugs commonly used to treat migraines are engineered. These methacrylate-based MIPs are synthesized, extracted, characterized, and used to quantitatively and directly detect over-the-counter drugs in complex samples using Raman microscopy. These results along with numerical approximation methods to estimate drug binding site densities and dissociation constants with

  6. Development and Characterization of Novel Nonlinear Optical Ultrathin Films from Preformed Polymers

    NASA Astrophysics Data System (ADS)

    Cheong, Dong-Wook

    This thesis focuses on the fabrication of Langmuir -Blodgett (LB) films of performed polymers to achieve improved non-linear optical (NLO) properties. Two different classes of polymers have been investigated in the course of this study, which include an asymmetrically substituted polydiacetylene and a polyamic acid containing p-nitroazobenzene as NLO side group. The polyamic acid film has been subsequently imidized to obtain polyimide thin films. The hydrophilic side groups distributed at regular short intervals along the backbone of these polymers assist the formation of stable polymeric monolayers at the air-water interface, which could be transferred to solid surfaces as multilayers for further characterization. An asymmetric polydiacetylene studied here is poly-{8- ((butoxycarbonyl-methyl)urethanyl) -1- (5-pyrimidyl) octa-1,3-diyne} (P-BPOD), consisting of hetero-aromatic pyrimidyl ring at one side and flexible urethane group at the other. Multilayers of P-BPOD could be deposited on hydrophobic surfaces in a non-centrosymmetric fashion. Both linear and non-linear optical experiments have suggested that P-BPOD molecules organize in a structure having inplane anisotropy and bulk asymmetry. The second harmonic generation (SHG) studies have indicated that the p-polarized SHG signal is higher when the polarization of the fundamental beam is parallel to the dipping direction than when it is perpendicular. The preferential orientation of the backbone along the dipping direction, induced by the shear force applied to the viscous polymeric monolayer, has resulted in an enhanced _chi^{(3)} along the dipping direction, which is an order of magnitude higher as compared to that along the perpendicular direction. These preformed polymeric LB films may provide ultrathin NLO films, which can be applied towards the fabrication of thin-film waveguides and optical-switching with definite technological advantages such as negligible film shrinkage (thus less defects) and improved

  7. Synthesis and characterization of functional polymers with controlled architecture and their application as anticorrosion primers

    NASA Astrophysics Data System (ADS)

    Quincy, Anne S.

    spectroscopy, polarization curves and pull-off test). A deposition method was developed to generate the optimal coating system: the steel to protect was dipped in a dilute solution of the copolymer, rinsed with pure solvent to eliminate the excess material and painted by spraying the epoxy mixture. Electrochemical techniques showed a 60% corrosion inhibition for the AEMA-GMA copolymers. An improvement of the epoxy coating corrosion resistance with the addition of the AEMA-GMA gradient copolymer and the AEMA-GMA star-block copolymer was noticed when subjected to hot water immersion and salt spray tests. While the polymeric primers showed to be quite effective in improving the coating's corrosion resistance, the common corrosion resistance tests were found to be inadequate to robustly characterize their full potential. Nonetheless, the functional copolymers polymer with controlled architecture, their formulation and improved testing techniques, present challenging and interesting work to continue for anticorrosion research.

  8. Synthesis and characterization of sulfonated poly(ether sulfone)s containing mesonaphthobifluorene for polymer electrolyte membrane fuel cell.

    PubMed

    Lim, Youngdon; Seo, Dongwan; Lee, Soonho; Hossain, Md Awlad; Lim, Jinseong; Lee, Sangyoung; Hong, Taehoon; Kim, Whangi

    2014-10-01

    The novel sulfonated poly(ether sulfone)s containing mesonaphthobifluorene (MNF) moiety were synthesized and characterized their properties. The prepared polymers have highly conjugated aromatic structure due to the MNF group which is an allotrope of carbon and one atom thick planar sheets of sp2-bonded carbon atoms. Poly(ether sulfone)s bearing tetraphenylethylene on polymer backbone were synthesized by polycondensation and followed intra-cyclization from tetraphenylethylene to form MNF by Friedel-craft reaction with Lewis acid (FeCl3). The sulfonation was performed selectively on MNF units with conc. sulfuric acid. The structural properties of the sulfonated polymers were investigated by 1H-NMR spectroscopy. The membranes were studied by ion exchange capacity (IEC), water uptake, and proton conductivity. The synthesized polymer electrolyte membranes showed better thermal and dimensional stabilities owing to the inducted highly conjugated aromatic structure in the polymer backbone. The water uptake of the synthesized membranes ranged from 23-52%, compared with 32.13% for Nafion 211 at 80 degrees C. The synthesized membranes exhibited proton conductivities (80 degrees C, RH 90%) of 74.6-100.4 mS/cm, compared with 102.7 mS/cm for Nafion 211.

  9. Thermal decomposition of sewage sludge under N2, CO2 and air: Gas characterization and kinetic analysis.

    PubMed

    Hernández, Ana Belén; Okonta, Felix; Freeman, Ntuli

    2017-03-25

    Thermochemical valorisation processes that allow energy to be recovered from sewage sludge, such as pyrolysis and gasification, have demonstrated great potential as convenient alternatives to conventional sewage sludge disposal technologies. Moreover, these processes may benefit from CO2 recycling. Today, the scaling up of these technologies requires an advanced knowledge of the reactivity of sewage sludge and the characteristics of the products, specific to the thermochemical process. In this study the behaviour of sewage sludge during thermochemical conversion, under different atmospheres (N2, CO2 and air), was studied, using TGA-FTIR, in order to understand the effects of different atmospheric gases on the kinetics of degradation and on the gaseous products. The different steps observed during the solid degradation were related with the production of different gaseous compounds. A higher oxidative degree of the atmosphere surrounding the sample resulted in higher reaction rates and a shift of the degradation mechanisms to lower temperatures, especially for the mechanisms taking place at temperatures above 400 °C. Finally, a multiple first-order reaction model was proposed to compare the kinetic parameters obtained under different atmospheres. Overall, the highest activation energies were obtained for combustion. This work proves that CO2, an intermediate oxidative atmosphere between N2 and air, results in an intermediate behaviour (intermediate peaks in the derivative thermogravimetric curves and intermediate activation energies) during the thermochemical decomposition of sewage sludge. Overall, it can be concluded that the kinetics of these different processes require a different approach for their scaling up and specific consideration of their characteristic reaction temperatures and rates should be evaluated.

  10. Fabrication and characterization of dry conducting polymer actuator by vapor phase polymerization of polypyrrole.

    PubMed

    Ramasamy, Madeshwaran Sekkarapatti; Mahapatra, Sibdas Singha; Cho, Jae Whan

    2014-10-01

    A trilayered dry conducting polymer actuator was fabricated via application of a polypyrrole (PPy) coating on both sides of a solid polymer electrolyte film using vapor phase polymerization (VPP). The solid polymer electrolyte film was prepared by incorporation of different weight ratios of dodecylbenzene sulfonic acid sodium salt in poly(vinyl alcohol) (PVA) by solvent casting. The successful polymerization of PPy was confirmed by Fourier transform infrared spectroscopy; a uniform PPy coating on the solid polymer electrolyte film surface was also observed by scanning electron microscopy. The dry PVA/PPy actuator demonstrated good actuation behavior at a low applied voltage of 1-3 V. The actuator bending displacement was found to increase with an increase in the applied voltage. The VPP approach in this study provides a very effective method for achieving a uniform polymer coating in the fabrication of a dry conducting polymer actuator.

  11. Design, Synthesis, and Characterization of High Performance Polymer Electrolytes for Printed Electronics and Energy Storage

    DTIC Science & Technology

    2016-03-31

    organic , polymer 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 19a.  NAME OF RESPONSIBLE PERSON LEE, CHARLES 19b...The overarching goal of this project was to develop a new generation of high performance polymer electrolytes for applications in electronics...performance and national defense capabilities. Importantly, while the specific requirements for polymer electrolytes vary with application , the basic

  12. Physicochemical characterization of in situ drug-polymer nanocomplex formed between zwitterionic drug and ionomeric material in aqueous solution.

    PubMed

    Salamanca, Constain H; Castillo, Duvan F; Villada, Juan D; Rivera, Gustavo R

    2017-03-01

    Biocompatible polymeric materials with the potential to form functional structures, in association with different therapeutic molecules, in physiological media, represent a great potential for biological and pharmaceutical applications. Therefore, here the formation of a nano-complex between a synthetic cationic polymer and model drug (ampicillin trihydrate) was studied. The formed complex was characterized by size and zeta potential measurements, using dynamic light scattering and capillary electrophoresis. Moreover, the chemical and thermodynamically stability of these complexes were studied. The ionomeric material, here referred as EuCl, was obtained by equimolar reaction between Eudragit E and HCl. The structural characterization was carried out by potentiometric titration, FTIR spectroscopy, and DSC. The effect of pH, time, polymer concentration and ampicillin/polymer molar ratio over the hydrodynamic diameter and zeta potential were established. The results show that EuCl ionomer in aqueous media presents two different populations of nanoparticles; one of this tends to form flocculated aggregates in high pH and concentrations, by acquiring different conformations in solution by changing from a compact to an extended conformation. Moreover, the formation of an in situ interfacial polymer-drug complex was demonstrated, this could slightly reduce the hydrolytic degradation of the drug while affecting its solubility, mainly under acidic conditions.

  13. Thermal Decomposition Behavior of Poly(3-nitratooxetane)

    NASA Astrophysics Data System (ADS)

    Mason, Brian; Cruz, Aliza; Stoltz, Chad

    2009-06-01

    Poly(3-nitratooxetane), or PNO, is a new high-energy density polymer that is expected to increase formulation energy output without sacrificing binder stability. It is anticipated that using PNO in propellant formulations will be advantageous compared to other energetic binders such as its structural isomer poly(glycidyl nitrate) (PGN). In an effort to understand the combustion behavior of this new energetic polymer, thermal decomposition of PNO has been investigated. Differential scanning calorimetry coupled with thermal gravimetric analysis shows that this material is thermally stable to at least 150^oC and that exothermic decomposition peaks near 203^oC. T- Jump/FTIR was used under various conditions to identify gas- phase thermal decomposition products, including H2O, CH2O, CO2, CO, N2O, NO, NO2, and HONO (cis and trans). Additional time- resolved T-Jump/FTIR experiments suggest immediate dissociation of NO2 as the obvious first step in PNO decomposition, while previous work on the PGN polymer system suggests that the entire CH2ONO2 side chain breaks from the PGN backbone before dissociation. It is likely that different decomposition pathways are followed for each binder system due to location of available C-O and N-O moieties on each polymer.

  14. All-polymer arrayed waveguide grating at 850  nm: design, fabrication, and characterization.

    PubMed

    Orghici, Rozalia; Bethmann, Konrad; Zywietz, Urs; Reinhardt, Carsten; Schade, Wolfgang

    2016-09-01

    In this Letter, a novel all-polymer arrayed waveguide grating (AWG) device with an operating wavelength around 850 nm is reported. The all-polymer AWG consists of polymer ridge waveguides fabricated on a thin poly(methyl methacrylate) foil via microscope projection photolithography. The developed device is suitable to be integrated into optical circuits, e.g., a planar polymer foil and, along with other optical integrated devices, to be used for different sensing applications. The functionality of the device is demonstrated by using a fiber Bragg grating sensor and performing strain measurements.

  15. Synthesis and Characterization of Molecularly Imprinted Polymer Membrane for the Removal of 2,4-Dinitrophenol

    PubMed Central

    Yusof, Nor Azah; Zakaria, Nor Dyana; Maamor, Nor Amirah Mohd; Abdullah, Abdul Halim; Haron, Md. Jelas

    2013-01-01

    Molecularly imprinted polymers (MIPs) were prepared by bulk polymerization in acetonitrile using 2,4-dinitrophenol, acrylamide, ethylene glycol dimethacrylate, and benzoyl peroxide, as the template, functional monomer, cross-linker, and initiator, respectively. The MIP membrane was prepared by hybridization of MIP particles with cellulose acetate (CA) and polystyrene (PS) after being ground and sieved. The prepared MIP membrane was characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. The parameters studied for the removal of 2,4-dinitrophenol included the effect of pH, sorption kinetics, and the selectivity of the MIP membrane. Maximum sorption of 2,4-nitrophenol by the fabricated CA membrane with MIP (CA-MIP) and the PS membrane with MIP (PS-MIP) was observed at pH 7.0 and pH 5.0, respectively. The sorption of 2,4-dinitrophenol by CA-MIP and PS-MIP followed a pseudo–second-order kinetic model. For a selectivity study, 2,4-dichlorophenol, 3-chlorophenol, and phenol were selected as potential interferences. The sorption capability of CA-MIP and PS-MIP towards 2,4-dinitrophenol was observed to be higher than that of 2,4-dichlorophenol, 3-chlorophenol, or phenol. PMID:23429189

  16. Synthesis and characterization of molecularly imprinted polymer membrane for the removal of 2,4-dinitrophenol.

    PubMed

    Yusof, Nor Azah; Zakaria, Nor Dyana; Maamor, Nor Amirah Mohd; Abdullah, Abdul Halim; Haron, Md Jelas

    2013-02-18

    Molecularly imprinted polymers (MIPs) were prepared by bulk polymerization in acetonitrile using 2,4-dinitrophenol, acrylamide, ethylene glycol dimethacrylate, and benzoyl peroxide, as the template, functional monomer, cross-linker, and initiator, respectively. The MIP membrane was prepared by hybridization of MIP particles with cellulose acetate (CA) and polystyrene (PS) after being ground and sieved. The prepared MIP membrane was characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. The parameters studied for the removal of 2,4-dinitrophenol included the effect of pH, sorption kinetics, and the selectivity of the MIP membrane. Maximum sorption of 2,4-nitrophenol by the fabricated CA membrane with MIP (CA-MIP) and the PS membrane with MIP (PS-MIP) was observed at pH 7.0 and pH 5.0, respectively. The sorption of 2,4-dinitrophenol by CA-MIP and PS-MIP followed a pseudo-second-order kinetic model. For a selectivity study, 2,4-dichlorophenol, 3-chlorophenol, and phenol were selected as potential interferences. The sorption capability of CA-MIP and PS-MIP towards 2,4-dinitrophenol was observed to be higher than that of 2,4-dichlorophenol, 3-chlorophenol, or phenol.

  17. Quantitative characterization of water transport and flooding in the diffusion layers of polymer electrolyte fuel cells

    NASA Astrophysics Data System (ADS)

    Casalegno, A.; Colombo, L.; Galbiati, S.; Marchesi, R.

    Optimization of water management in polymer electrolyte membrane fuel cells (PEMFC) and in direct methanol fuel cells (DMFC) is a very important factor for the achievement of high performances and long lifetime. A good hydration of the electrolyte membrane is essential for high proton conductivity; on the contrary water in excess may lead to electrode flooding and severe reduction in performances. Many studies on water transport across the gas diffusion layer (GDL) have been carried out to improve these components; anyway efforts in this field are affected by lack of effective experimental methods. The present work reports an experimental investigation with the purpose to determine the global coefficient of water transport across different diffusion layers under real operating conditions. An appropriate and accurate experimental apparatus has been designed and built to test the single GDL under a wide range of operating conditions. Data analysis has allowed quantification of both the water vapor transport across different diffusion layers, and the effects of micro-porous layers; furthermore flooding onset and its consequences on the mass transport coefficient have been characterized by means of suitably defined parameters.

  18. Characterization and analysis of carbon fibre-reinforced polymer composite laminates with embedded circular vasculature.

    PubMed

    Huang, C-Y; Trask, R S; Bond, I P

    2010-08-06

    A study of the influence of embedded circular hollow vascules on structural performance of a fibre-reinforced polymer (FRP) composite laminate is presented. Incorporating such vascules will lead to multi-functional composites by bestowing functions such as self-healing and active thermal management. However, the presence of off-axis vascules leads to localized disruption to the fibre architecture, i.e. resin-rich pockets, which are regarded as internal defects and may cause stress concentrations within the structure. Engineering approaches for creating these simple vascule geometries in conventional FRP laminates are proposed and demonstrated. This study includes development of a manufacturing method for forming vascules, microscopic characterization of their effect on the laminate, finite element (FE) analysis of crack initiation and failure under load, and validation of the FE results via mechanical testing observed using high-speed photography. The failure behaviour predicted by FE modelling is in good agreement with experimental results. The reduction in compressive strength owing to the embedding of circular vascules ranges from 13 to 70 per cent, which correlates with vascule dimension.

  19. Preparation and Characterization of Nanocomposite Polymer Membranes Containing Functionalized SnO2 Additives

    PubMed Central

    Scipioni, Roberto; Gazzoli, Delia; Teocoli, Francesca; Palumbo, Oriele; Paolone, Annalisa; Ibris, Neluta; Brutti, Sergio; Navarra, Maria Assunta

    2014-01-01

    In the research of new nanocomposite proton-conducting membranes, SnO2 ceramic powders with surface functionalization have been synthesized and adopted as additives in Nafion-based polymer systems. Different synthetic routes have been explored to obtain suitable, nanometer-sized sulphated tin oxide particles. Structural and morphological characteristics, as well as surface and bulk properties of the obtained oxide powders, have been determined by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) and Raman spectroscopies, N2 adsorption, and thermal gravimetric analysis (TGA). In addition, dynamic mechanical analysis (DMA), atomic force microscopy (AFM), thermal investigations, water uptake (WU) measurements, and ionic exchange capacity (IEC) tests have been used as characterization tools for the nanocomposite membranes. The nature of the tin oxide precursor, as well as the synthesis procedure, were found to play an important role in determining the morphology and the particle size distribution of the ceramic powder, this affecting the effective functionalization of the oxides. The incorporation of such particles, having sulphate groups on their surface, altered some peculiar properties of the resulting composite membrane, such as water content, thermo-mechanical, and morphological characteristics. PMID:24957125

  20. Preparation and Characterization of Space Durable Polymer Nanocomposite Films from Functionalized Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Delozier, D. M.; Connell, J. W.; Smith, J. G.; Watson, K. A.

    2003-01-01

    Low color, flexible, space durable polyimide films with inherent, robust electrical conductivity have been under investigation as part of a continuing materials development activity for future NASA space missions involving Gossamer structures. Electrical conductivity is needed in these films to dissipate electrostatic charge build-up that occurs due to the orbital environment. One method of imparting conductivity is through the use of single walled carbon nanotubes (SWNTs). However, the incompatibility and insolubility of the SWNTs severely hampers their dispersion in polymeric matrices. In an attempt to improve their dispersability, SWNTs were functionalized by the reaction with an alkyl hydrazone. After this functionalization, the SWNTs were soluble in select solvents and dispersed more readily in the polymer matrix. The functionalized SWNTs were characterized by Raman spectroscopy and thermogravimetric analysis (TGA). The functionalized nanotubes were dispersed in the bulk of the films using a solution technique. The functionalized nanotubes were also applied to the surface of polyimide films using a spray coating technique. The resultant polyimide nanocomposite films were evaluated for nanotube dispersion, electrical conductivity, mechanical, and optical properties and compared with previously prepared polyimide-SWNT samples to assess the effects of SWNT functionalization.

  1. Optical and electrical characterizations of multifunctional silver phosphate glass and polymer-based optical fibers.

    PubMed

    Rioux, Maxime; Ledemi, Yannick; Morency, Steeve; de Lima Filho, Elton Soares; Messaddeq, Younès

    2017-03-03

    In recent years, the fabrication of multifunctional fibers has expanded for multiple applications that require the transmission of both light and electricity. Fibers featuring these two properties are usually composed either of a single material that supports the different characteristics or of a combination of different materials. In this work, we fabricated (i) novel single-core step-index optical fibers made of electrically conductive AgI-AgPO3-WO3 glass and (ii) novel multimaterial fibers with different designs made of AgI-AgPO3-WO3 glass and optically transparent polycarbonate and poly (methyl methacrylate) polymers. The multifunctional fibers produced show light transmission over a wide range of wavelengths from 500 to 1000 nm for the single-core fibers and from 400 to 1000 nm for the multimaterial fibers. Furthermore, these fibers showed excellent electrical conductivity with values ranging between 10(-3) and 10(-1) S·cm(-1) at room temperature within the range of AC frequencies from 1 Hz to 1 MHz. Multimodal taper-tipped fibre microprobes were then fabricated and were characterized. This advanced design could provide promising tools for in vivo electrophysiological experiments that require light delivery through an optical core in addition to neuronal activity recording.

  2. Characterization of multi-layered impact damage in polymer matrix composites using lateral thermography

    NASA Astrophysics Data System (ADS)

    Whitlow, Travis; Sathish, Shamachary

    2017-02-01

    Polymer matrix composites (PMCs) are increasingly being integrated into aircraft structures. However, these components are susceptible to impact related delamination, which, on aircrafts, can occur due to a number of reasons during aircraft use and maintenance. Quantifying impact damage is an important aspect for life-management of aircraft and requires in-depth knowledge of the damage zone on a ply-by-ply level. Traditionally, immersion ultrasound has provided relative high resolution images of impact damage. Ultrasonic time-of-flight data can be used to determine the front surface delamination depth and an approximation of the delaminated area. However, such inspections require the material to be immersed in water and can be time consuming. The objective of this work is to develop a quick and robust methodology to non-destructively characterize multi-layered impact damage using lateral thermography. Initial results suggest lateral heat flow is sensitive to the depth of impact damage. The anticipated outcome of this project is to estimate the extent of through-thickness impact damage. Initial results are shown and future efforts are discussed.

  3. Characterization of nanoscale spatial distribution of small molecules in amorphous polymer matrices

    NASA Astrophysics Data System (ADS)

    Ricarte, Ralm; Hillmyer, Marc; Lodge, Timothy

    Hydroxypropyl methylcellulose acetate succinate (HPMCAS) can significantly enhance the efficacy of active pharmaceutical ingredients (APIs). Yet, the interactions between species in HPMCAS-API blends are not understood. Elucidating these interactions is difficult because the spatial distributions of HPMCAS and API in the blends are ambiguous; the polymer and drug may be molecularly mixed or the species may form phase separated domains. As these phase separated domains may be less than 100 nm in size, traditional characterization techniques may not accurately evaluate the spatial distribution. To address this challenge, we explore the use of electron energy-loss spectroscopy (EELS) for detecting the model API phenytoin in an HPMCAS-phenytoin blend. Using EELS, we directly measured with high accuracy and precision the phenytoin concentrations in several blends. We present evidence that suggests phase separation occurs in blends that have a phenytoin loading of approximately 50 wt percent. Finally, we demonstrate that this technique achieves a sub-100 nm spatial resolution and can detect several other APIs.

  4. Synthesis, characterization, and antibacterial activities of novel methacrylate polymers containing norfloxacin.

    PubMed

    Dizman, Bekir; Elasri, Mohamed O; Mathias, Lon J

    2005-01-01

    A novel methacrylate monomer containing a quinolone moiety was synthesized and homopolymerized in N,N-dimethylformamide (DMF) by using azobisisobutyronitrile (AIBN) as an initiator. The new monomer was copolymerized with poly(ethylene glycol) methyl ether methacrylate (MPEGMA) in DMF using the same initiator. The monomer, homopolymer, and copolymer were characterized by elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), size exclusion chromatography (SEC), FTIR, (13)C NMR, and (1)H NMR. The antibacterial activities of the monomer as well as polymers were investigated against Staphylococcus aureus and Escherichia coli, which are representative of Gram-positive and Gram-negative bacteria, respectively. All compounds showed excellent antibacterial activities against these two types of bacteria. The antibacterial activities were determined using the shaking flask method, where 25 mg/mL concentrations of each compound were tested against 10(5) CFU/mL bacteria solutions. The number of viable bacteria was calculated by using the spread plate method, where 100 microL of the incubated antibacterial agent in bacteria solutions were spread on agar plates and the number of viable bacteria was counted after 24 h of incubation period at 37 degrees C.

  5. Synthesis and Characterization of Polymer Nanocarriers for the Targeted Delivery of Therapeutic Enzymes

    PubMed Central

    Simone, Eric; Dziubla, Thomas; Shuvaev, Vladimir; Muzykantov, Vladimir R.

    2011-01-01

    Protein drugs, such as recombinant enzymes useful for detoxification and replacement therapies, have extraordinary specificity and potency. However, inherently inadequate delivery to target sites and rapid inactivation limit their medical utility. Using chaperone polymeric particles designed within an injectible size range (sub-micron) may help solve these shortcomings. Such nanocarriers would (i) prevent premature inactivation of encapsulated therapeutic protein cargoes, (ii) provide a carrier that can be surface decorated by targeting ligands, and (iii) optimize sub-cellular localization of the drug. This chapter describes the techniques successfully employed for the preparation of polymer nanocarriers (PNC) loaded with the antioxidant enzyme, catalase, and targeted to endothelial cells. Methods of PNC synthesis, loading with catalase, characterization, coupling of a targeting moiety, and in vitro testing of the enzymatic and targeting activities are provided here. Advantages and disadvantages of specific designs are discussed. Due to the modular nature of the targeting methodology employed, it is believed that these protocols will provide a solid foundation for the formulation of a wide variety of enzymatic drug targeting strategies. PMID:20013177

  6. Preparation, characterization and selective recognition for vanillic acid imprinted mesoporous silica polymers

    NASA Astrophysics Data System (ADS)

    Li, Hui; Xu, Miaomiao; Wang, Susu; Lu, Cuimei; Li, Zhiping

    2015-02-01

    A vanillic acid imprinted mesoporous silica polymer (MIPs) was prepared by copolymerizing a modified mesoporous silica molecular sieve with template molecule, functional monomer and cross-linker in present work. Interaction between the template and functional monomer was investigated by ultraviolet/visible spectrophotometry. These MIPs were characterized by Fourier transmission infrared spectrometry (FTIR) and scanning electron microscopy (SEM). Adsorption dynamics and thermodynamic behavior of MIPs was explored and the selective recognition capability evaluated. Also, the applicability for the MIPs as solid phase extraction media was tested. Results indicated the 1:1 (mole ratio) complex of vanillic acid-4-vinylpyridine might predominate in the pre-polymerization mixture and the MIPs obtained possessed rapid binding dynamics and higher affinity toward template molecules, reaching adsorption equilibrium within 230 min with the highest adsorption amount of 50.7 mg g-1. Freundlich model was shown best to describe isotherm adsorption for the MIPs. The MIPs could selectively bind template molecule with selectivity coefficients of 1.36-1.50. In addition, a higher enrichment capability when using it for gathering target compound from methanol extract of Artemisia stelleriana and a good reusability during adsorption-desorption recycling use could be observed.

  7. Preparation and characterization of nanocomposite polymer electrolytes poly(vinylidone fluoride)/nanoclay

    SciTech Connect

    Rahmawati, Suci A.; Sulistyaningsih,; Putro, Alviansyah Z. A.; Widyanto, Nugroho F.; Jumari, Arif; Purwanto, Agus; Dyartanti, Endah R.

    2016-02-08

    Polymer electrolytes are defined as semi solid electrolytes used as separator in lithium ion battery. Separator used as medium for transfer ions and to prevent electrical short circuits in battery cells. To obtain the optimal battery performance, separator with high porosity and electrolyte uptake is required. This can reduce the resistance in the transfer of ions between cathode and anode. The main objective of this work is to investigate the impact of different solvent (Dimethyl acetamide (DMAc), N-methyl-2-pyrrolidone (NMP) and dimethyl formamide (DMF)), pore forming agent poly(vinylpyrolidone) (PVP) and nanoclay as filler in addition of membrane using phase inversion method on the morphology, porosity, electrolyte uptake and degree of crystallinity. The membrane was prepared by the phase inversion method by adding PVP and Nanoclay using different solvents. The phase inversion method was prepared by dissolving Nanoclay and PVP in solvent for 1-2 hours, and then add the PVDF with stirring for 4 hours at 60°C. The membranes were characterized by porosity test, electrolyte uptake test, scanning electron microscope (SEM), and X-ray diffraction (XRD). The results showed that DMAc as solvent gives the highest value of porosity and electrolyte uptake. The addition of nanoclay and PVP enlarge the size of the pores and reduce the degree of crystallinity. So, the usage of DMAc as solvent is better than NMP or DMF.

  8. Polymer based flapping-wing robotic insect: Progress in design, fabrication, and characterization

    NASA Astrophysics Data System (ADS)

    Bontemps, A.; Vanneste, T.; Soyer, C.; Paquet, J. B.; Grondel, S.; Cattan, E.

    2014-03-01

    In the last decade, many researchers pursued the development of tiny flying robots inspired by natural flyers destined for the exploration of confined spaces, for example. Within this context, our main objective is to devise a flying robot bioinspired from insect in terms of size and wing kinematics using MEMS technologies. For this purpose, an original design has been developed around resonant thorax and wings by the way of an indirect actuation and a concise transmission whereas the all-polymer prototypes are obtained using a micromachining SU-8 photoresist process. This paper reports our recent progress on the design of a flapping-wing robotic insect as well as on the characterization of its performance. Prototypes with a wingspan of 3 cm and a mass of 22 mg are achieved. Due to the introduction of an innovative compliant link, large and symmetrical bending angles of 70° are obtained at a flapping frequency of 30 Hz along with passive wing torsion while minimizing its energy expenditure. Furthermore, it leads to a mean lift force representing up to 75 % of the prototype weight as measured by an in-house force sensor. Different improvements are currently underway to increase the power-to-weight ratio of the prototype and to obtain an airborne prototype.

  9. Characterization of UV-cured gel polymer electrolytes for rechargeable lithium batteries

    NASA Astrophysics Data System (ADS)

    Song, Min-Kyu; Cho, Jin-Yeon; Cho, Byung Won; Rhee, Hee-Woo

    Novel ultraviolet (UV)-cured gel polymer electrolytes based on polyethyleneglycol diacrylate (PEGDA) oligomer and polyvinylidene fluoride (PVdF) are prepared and characterized. UV-curing of PEGDA oligomer containing PVdF and ethylene carbonate (EC)-based liquid electrolyte yields chemically and physically cross-linked PEGDA/PVdF blend gel electrolytes. PEGDA/PVdF blend films show much higher mechanical properties and electrolyte liquid retention than pure PEGDA film. The ionic conductivity ( σ) of a PEGDA/PVdF (5/5) blend electrolyte reaches about 4 mS cm -1 at ambient temperature and is as high as 1 mS cm -1 at 0 °C. All the blend electrolytes are electrochemically stable up to 4.6 V versus Li/Li +. The cation transference number ( t+) measured by dc micropolarization exceeds 0.5 at room temperature. Li/(PEGDA/PVdF)/LiCoO 2 cells ( 2 cm×2 cm) retains >91% of its initial discharge capacity after 50 cycles at the C/3 rate (2 mA cm -2) and delivers about 70% of full capacity with an average load voltage of 3.6 V at the C/1 rate. Cell performance is stable up to 80 °C because PVdF chains might be stabilized by entanglement with the chemically cross-linked PEGDA network structure.

  10. 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.

  11. Preparation and characterization of nanocomposite polymer electrolytes poly(vinylidone fluoride)/nanoclay

    NASA Astrophysics Data System (ADS)

    Rahmawati, Suci A.; Sulistyaningsih, Putro, Alviansyah Z. A.; Widyanto, Nugroho F.; Jumari, Arif; Purwanto, Agus; Dyartanti, Endah R.

    2016-02-01

    Polymer electrolytes are defined as semi solid electrolytes used as separator in lithium ion battery. Separator used as medium for transfer ions and to prevent electrical short circuits in battery cells. To obtain the optimal battery performance, separator with high porosity and electrolyte uptake is required. This can reduce the resistance in the transfer of ions between cathode and anode. The main objective of this work is to investigate the impact of different solvent (Dimethyl acetamide (DMAc), N-methyl-2-pyrrolidone (NMP) and dimethyl formamide (DMF)), pore forming agent poly(vinylpyrolidone) (PVP) and nanoclay as filler in addition of membrane using phase inversion method on the morphology, porosity, electrolyte uptake and degree of crystallinity. The membrane was prepared by the phase inversion method by adding PVP and Nanoclay using different solvents. The phase inversion method was prepared by dissolving Nanoclay and PVP in solvent for 1-2 hours, and then add the PVDF with stirring for 4 hours at 60°C. The membranes were characterized by porosity test, electrolyte uptake test, scanning electron microscope (SEM), and X-ray diffraction (XRD). The results showed that DMAc as solvent gives the highest value of porosity and electrolyte uptake. The addition of nanoclay and PVP enlarge the size of the pores and reduce the degree of crystallinity. So, the usage of DMAc as solvent is better than NMP or DMF.

  12. Characterization and Analysis of Triaxially Braided Polymer Composites under Static and Impact Loads

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Roberts, Gary D.; Blinzler, Brina J.; Kohlman, Lee W.; Binienda, Wieslaw K.

    2012-01-01

    In order to design impact resistant aerospace components made of triaxially-braided polymer matrix composite materials, a need exists to have reliable impact simulation methods and a detailed understanding of the material behavior. Traditional test methods and specimen designs have yielded unrealistic material property data due to material mechanisms such as edge damage. To overcome these deficiencies, various alternative testing geometries such as notched flat coupons have been examined to alleviate difficulties observed with standard test methods. The results from the coupon level tests have been used to characterize and validate a macro level finite element-based model which can be used to simulate the mechanical and impact response of the braided composites. In the analytical model, the triaxial braid unit cell is approximated by using four parallel laminated composites, each with a different fiber layup, which roughly simulates the braid architecture. In the analysis, each of these laminated composites is modeled as a shell element. Currently, each shell element is considered to be a smeared homogeneous material. Simplified micromechanics techniques and lamination theory are used to determine the equivalent stiffness properties of each shell element, and results from the coupon level tests on the braided composite are used to back out the strength properties of each shell element. Recent improvements to the model include the incorporation of strain rate effects into the model. Simulations of ballistic impact tests have been carried out to investigate and verify the analysis approach.

  13. Characterization and analysis of carbon fibre-reinforced polymer composite laminates with embedded circular vasculature

    PubMed Central

    Huang, C.-Y.; Trask, R. S.; Bond, I. P.

    2010-01-01

    A study of the influence of embedded circular hollow vascules on structural performance of a fibre-reinforced polymer (FRP) composite laminate is presented. Incorporating such vascules will lead to multi-functional composites by bestowing functions such as self-healing and active thermal management. However, the presence of off-axis vascules leads to localized disruption to the fibre architecture, i.e. resin-rich pockets, which are regarded as internal defects and may cause stress concentrations within the structure. Engineering approaches for creating these simple vascule geometries in conventional FRP laminates are proposed and demonstrated. This study includes development of a manufacturing method for forming vascules, microscopic characterization of their effect on the laminate, finite element (FE) analysis of crack initiation and failure under load, and validation of the FE results via mechanical testing observed using high-speed photography. The failure behaviour predicted by FE modelling is in good agreement with experimental results. The reduction in compressive strength owing to the embedding of circular vascules ranges from 13 to 70 per cent, which correlates with vascule dimension. PMID:20150337

  14. Optical and electrical characterizations of multifunctional silver phosphate glass and polymer-based optical fibers

    NASA Astrophysics Data System (ADS)

    Rioux, Maxime; Ledemi, Yannick; Morency, Steeve; de Lima Filho, Elton Soares; Messaddeq, Younès

    2017-03-01

    In recent years, the fabrication of multifunctional fibers has expanded for multiple applications that require the transmission of both light and electricity. Fibers featuring these two properties are usually composed either of a single material that supports the different characteristics or of a combination of different materials. In this work, we fabricated (i) novel single-core step-index optical fibers made of electrically conductive AgI-AgPO3-WO3 glass and (ii) novel multimaterial fibers with different designs made of AgI-AgPO3-WO3 glass and optically transparent polycarbonate and poly (methyl methacrylate) polymers. The multifunctional fibers produced show light transmission over a wide range of wavelengths from 500 to 1000 nm for the single-core fibers and from 400 to 1000 nm for the multimaterial fibers. Furthermore, these fibers showed excellent electrical conductivity with values ranging between 10‑3 and 10‑1 S·cm‑1 at room temperature within the range of AC frequencies from 1 Hz to 1 MHz. Multimodal taper-tipped fibre microprobes were then fabricated and were characterized. This advanced design could provide promising tools for in vivo electrophysiological experiments that require light delivery through an optical core in addition to neuronal activity recording.

  15. Optical and electrical characterizations of multifunctional silver phosphate glass and polymer-based optical fibers

    PubMed Central

    Rioux, Maxime; Ledemi, Yannick; Morency, Steeve; de Lima Filho, Elton Soares; Messaddeq, Younès

    2017-01-01

    In recent years, the fabrication of multifunctional fibers has expanded for multiple applications that require the transmission of both light and electricity. Fibers featuring these two properties are usually composed either of a single material that supports the different characteristics or of a combination of different materials. In this work, we fabricated (i) novel single-core step-index optical fibers made of electrically conductive AgI-AgPO3-WO3 glass and (ii) novel multimaterial fibers with different designs made of AgI-AgPO3-WO3 glass and optically transparent polycarbonate and poly (methyl methacrylate) polymers. The multifunctional fibers produced show light transmission over a wide range of wavelengths from 500 to 1000 nm for the single-core fibers and from 400 to 1000 nm for the multimaterial fibers. Furthermore, these fibers showed excellent electrical conductivity with values ranging between 10−3 and 10−1 S·cm−1 at room temperature within the range of AC frequencies from 1 Hz to 1 MHz. Multimodal taper-tipped fibre microprobes were then fabricated and were characterized. This advanced design could provide promising tools for in vivo electrophysiological experiments that require light delivery through an optical core in addition to neuronal activity recording. PMID:28256608

  16. Preparation and characterization of magnetic molecularly imprinted polymers for the extraction of hexamethylenetetramine in milk samples.

    PubMed

    Xu, Xing; Duhoranimana, Emmanuel; Zhang, Xiaoming

    2017-01-15

    Magnetic molecularly imprinted polymers (M-MIPs) were synthesized as the sorbents for extracting hexamethylenetetramine (HMT) from milk samples. Molecular simulations were used to calculate the interaction energies of the template monomers. The physical properties of M-MIPs were characterized. The adsorption isotherms and kinetics were investigated. Gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) was applied to determine the amount of HMT residue in milk samples. In the optimized method, a linear calibration curve was obtained using a matrix-matched standard in the range of 1.0-50.0μgL(-1). The limit of detection (LOD) and limit of quantification (LOQ) was 0.3μgkg(-1) and 1.0μgkg(-1), respectively. The relative standard deviation (RSD) of the intra-day assay ranged from 2.6% to 5.2%, while that of the inter-day assay ranged from 3.6% to 11.5%. The recovery of HMT in milk samples ranged from 88.7% to 111.4%.

  17. Synthesis and characterization of hot pressed ion conducting solid polymer electrolytes: (1 - x) PEO: x NaClO4

    NASA Astrophysics Data System (ADS)

    Chandra, Angesh; Chandra, Archana; Thakur, Kiran

    2015-02-01

    Synthesis and ion transport characterization of hot-pressed poly(ethylene oxide) PEO-based solid polymer electrolytes (SPEs): (1 - x) PEO: x NaClO4, where 0 < x < 50 wt.%, are reported. The composition: (70PEO: 30NaClO4) with ionic conductivity (σ) ~ 7.07 × 10-7 S cm-1 shows the highest conducting composition and this have been referred to as optimum conducting composition (OCC). Materials characterization and thermal behavior of the present SPEs have been done with the help of XRD, FTIR, SEM, DSC and TG analysis. To determine the activation energy, temperature dependent ionic conductivity (σ) of different compositions has been measured. Ionic nature of the SPEs has been explained with the help of ionic transference number (tion) measurements. Finally, the thin film polymer battery is also fabricated using the SPE OCC as electrolyte and calculated their cell parameters at room temperature.

  18. Preparation and characterization of organotin-oxomolybdate coordination polymers and their use in sulfoxidation catalysis.

    PubMed

    Abrantes, Marta; Valente, Anabela A; Pillinger, Martyn; Gonçalves, Isabel S; Rocha, João; Romão, Carlos C

    2003-06-16

    The organotin-oxomolybdates [(R(3)Sn)(2)MoO(4)].n H(2)O (R=methyl, n-butyl, cyclohexyl, phenyl, benzyl) have been prepared and tested as catalysts for the oxidation of benzothiophene with aqueous hydrogen peroxide, at 35 degrees C and atmospheric pressure. In all cases, the 1,1-dioxide was the only observed product. The kinetic profiles depend on the nature of the tin-bound R group and also on the addition of a co-solvent. For the tribenzyltin derivative, the apparent activation energies for sulfoxidation as a function of the co-solvent are in the order 1,2-dichloroethane (5 kcal mol(-1))polymers also have different structures, as evidenced by Xray powder diffraction. Mo K-edge and Sn K-edge EXAFS spectroscopy confirmed that the structures arise from the self-assembly of tetrahedral [MoO(4)](2-) subunits and [R(3)Sn](+) spacers. The Mo...Sn separation in the trimethyltin derivative is a uniform 3.84 A. By contrast, the EXAFS results revealed the coexistence of short (3.67-3.79 A) and long (3.93-4.07 A) Mo.Sn separations in the other coordination polymers. The catalyst precursors were also characterized in the solid state by thermogravimetric analysis, FTIR, and Raman spectroscopy, and MAS NMR ((13)C, (119)Sn) spectroscopy.

  19. Experimental characterization of thermo-oxidation induced shrinkage and damage onset in polymer matrix composites at high temperature

    NASA Astrophysics Data System (ADS)

    Vu, D. Q.; Gigliotti, M.; Lafarie, M. C.; Grandidier, J. C.

    2010-06-01

    This paper focuses on the experimental characterization of thermo-oxidation in carbon fibre reinforced polymers (CFRP) exposed to “high” temperatures (up to 150°C) and “high” oxygen pressures (up to 5 bars). Thermo-oxidation induces matrix shrinkage and damage in CFRP. In this study these are both investigated at room temperature by means of confocal interferometric microscopy (CIM) and scanning electron microscopy (SEM).

  20. Characterization of polymers of adenosine diphosphate ribose generated in vitro and in vivo.

    PubMed

    Alvarez-Gonzalez, R; Jacobson, M K

    1987-06-02

    Methods have been developed and applied to determine the size and branching frequency of polymers of ADP-ribose synthesized in nucleotide-permeable cultured mouse cells and in intact cultured cells. Polymers were purified by affinity chromatography with a boronate resin and were fractionated according to size molecular sieve high-performance liquid chromatography. Fractions were enzymatically digested to nucleotides, which were separated by strong anion exchange high-performance liquid chromatography. From these data, average polymer size and branching frequency were calculated. A wide range of polymer sizes was observed. Polymers as large as 190 residues with at least five points of branching per molecule were generated in vitro. Polymers of up to 67 residues containing up to two points of branching per molecule were isolated from intact cells following treatment with the DNA alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine. Cells treated with hyperthermia prior to DNA damage contained polymers of an average maximum size of 244 residues containing up to six points of branching per molecule. The detection of large polymers of ADP-ribose in intact cells suggests that alterations in chromatin organization effected by poly(ADP-ribosylation) may extend beyond the covalently modified proteins and very likely involve noncovalent interactions of poly(ADP-ribose) with other components of chromatin.

  1. Hyperbranched polymer vesicles: from self-assembly, characterization, mechanisms, and properties to applications.

    PubMed

    Jiang, Wenfeng; Zhou, Yongfeng; Yan, Deyue

    2015-06-21

    Vesicles, including lipid vesicles, surfactant vesicles, as well as polymer vesicles, have been extensively investigated over the past fifty years. Among them, polymer vesicles have attracted more and more attention because of their low permeability, superior stability and toughness, in addition to the numerous possibilities for tailoring physical, chemical and biological properties. Polymer vesicles are generally fabricated through the self-assembly of amphiphilic polymers with a linear architecture. Recently, as representative polymers with a highly branched three-dimensional architecture, hyperbranched polymers have also exhibited great potential for preparing vesicles. The resultant hyperbranched polymer vesicles, defined as branched-polymersomes (BPs), have shown unique properties, such as giant and easily tuned vesicle sizes, facile functionalization, a special formation mechanism, and appealing solution behaviours. In this tutorial review, ten years of advances in BPs have been summarized since their first discovery in the year 2004, including the syntheses of vesicle-forming hyperbranched polymers, self-assembly methods, self-assembly mechanisms, as well as the special properties. In addition, the cytomimetic, biomedical and other initiatory applications of BPs are also included.

  2. Sub-10-Minute Characterization of an Ultrahigh Molar Mass Polymer by Multi-detector Hydrodynamic Chromatography

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molar mass averages, distributions, and architectural information of polymers are routinely obtained using size-exclusion chromatography (SEC). It has previously been shown that ultrahigh molar mass polymers may experience degradation during SEC analysis, leading to inaccurate molar mass averages a...

  3. Ordered macroporous quercetin molecularly imprinted polymers: Preparation, characterization, and separation performance.

    PubMed

    Feng, Yonggang; Liu, Qin; Ye, Lifang; Wu, Quanzhou; He, Jianfeng

    2017-02-01

    Ordered macroporous molecularly imprinted polymers were prepared by a combination of the colloidal crystal templating method and the molecular imprinting technique by using SiO2 colloidal crystal as the macroporogen, quercetin as the imprinting template, acrylamide as the functional monomer, ethylene glycol dimethacrylate as the cross-linker and tetrahydrofuran as the solvent. Scanning electron microscopy and Brunauer-Emmett-Teller measurements show that the ordered macroporous molecularly imprinted polymers have a more regular macroporous structure, a narrower pore distribution and a greater porosity compared with the traditional bulk molecularly imprinted polymers. The kinetic and isothermal adsorption behaviors of the polymers were investigated. The results indicate that the ordered macroporous molecularly imprinted polymers have a faster intraparticle mass transfer process and a higher adsorption capacity than the traditional bulk molecularly imprinted polymers. The ordered macroporous molecularly imprinted polymers were further employed as a sorbent for a solid-phase extraction. The results show that the ordered macroporous molecularly imprinted polymers can effectively separate quercetin from the Gingko hydrolysate.

  4. Assessment and characterization of the total geometric uncertainty in Gamma Knife radiosurgery using polymer gels

    SciTech Connect

    Moutsatsos, A.; Karaiskos, P.; Pantelis, E.; Georgiou, E.; Petrokokkinos, L.; Sakelliou, L.; Torrens, M.; Seimenis, I.

    2013-03-15

    Purpose: This work proposes and implements an experimental methodology, based on polymer gels, for assessing the total geometric uncertainty and characterizing its contributors in Gamma Knife (GK) radiosurgery. Methods: A treatment plan consisting of 26, 4-mm GK single shot dose distributions, covering an extended region of the Leksell stereotactic space, was prepared and delivered to a polymer gel filled polymethyl methacrylate (PMMA) head phantom (16 cm diameter) used to accurately reproduce every link in the GK treatment chain. The center of each shot served as a 'control point' in the assessment of the GK total geometric uncertainty, which depends on (a) the spatial dose delivery uncertainty of the PERFEXION GK unit used in this work, (b) the spatial distortions inherent in MR images commonly used for target delineation, and (c) the geometric uncertainty contributor associated with the image registration procedure performed by the Leksell GammaPlan (LGP) treatment planning system (TPS), in the case that registration is directly based on the apparent fiducial locations depicted in each MR image by the N-shaped rods on the Leksell localization box. The irradiated phantom was MR imaged at 1.5 T employing a T2-weighted pulse sequence. Four image series were acquired by alternating the frequency encoding axis and reversing the read gradient polarity, thus allowing the characterization of the MR-related spatial distortions. Results: MR spatial distortions stemming from main field (B{sub 0}) inhomogeneity as well as from susceptibility and chemical shift phenomena (also known as sequence dependent distortions) were found to be of the order of 0.5 mm, while those owing to gradient nonlinearities (also known as sequence independent distortions) were found to increase with distance from the MR scanner isocenter extending up to 0.47 mm at an Euclidean distance of 69.6 mm. Regarding the LGP image registration procedure, the corresponding average contribution to the total

  5. A real-time plane-wave decomposition algorithm for characterizing perforated liners damping at multiple mode frequencies.

    PubMed

    Zhao, Dan

    2011-03-01

    Perforated liners with a narrow frequency range are widely used as acoustic dampers to stabilize combustion systems. When the frequency of unstable modes present in the combustion system is within the effective frequency range, the liners can efficiently dissipate acoustic waves. The fraction of the incident waves being absorbed (known as power absorption coefficient) is generally used to characterize the liners damping. To estimate it, plane waves either side of the liners need to be decomposed and characterized. For this, a real-time algorithm is developed. Emphasis is being placed on its ability to online decompose plane waves at multiple mode frequencies. The performance of the algorithm is evaluated first in a numerical model with two unstable modes. It is then experimentally implemented in an acoustically driven pipe system with a lined section attached. The acoustic damping of perforated liners is continuously characterized in real-time. Comparison is then made between the results from the algorithm and those from the short-time fast Fourier transform (FFT)-based techniques, which are typically used in industry. It was found that the real-time algorithm allows faster tracking of the liners damping, even when the forcing frequency was suddenly changed.

  6. Characterization of proton conducting blend polymer electrolyte using PVA-PAN doped with NH4SCN

    NASA Astrophysics Data System (ADS)

    Premalatha, M.; Mathavan, T.; Selvasekarapandian, S.; Genova, F. Kingslin Mary; Umamaheswari, R.

    2016-05-01

    Polymer electrolytes with proton conductivity based on blend polymer using polyvinyl alcohol (PVA) and poly acrylo nitrile (PAN) doped with ammonium thiocyanate have been prepared by solution casting method using DMF as solvent. The complex formation between the blend polymer and the salt has been confirmed by FTIR Spectroscopy. The amorphous nature of the blend polymer electrolytes have been confirmed by XRD analysis. The highest conductivity at 303 K has been found to be 3.25 × 10-3 S cm-1 for 20 mol % NH4SCN doped 92.5PVA:7.5PAN system. The increase in conductivity of the doped blend polymer electrolytes with increasing temperature suggests the Arrhenius type thermally activated process. The activation energy is found to be low (0.066 eV) for the highest conductivity sample.

  7. Synthesis and characterization of functional thienyl-phosphine microporous polymers for carbon dioxide capture.

    PubMed

    Chen, Xianghui; Qiao, Shanlin; Du, Zhengkun; Zhou, Yuanhang; Yang, Renqiang

    2013-07-25

    A novel kind of functional organic microporous polymer is designed by introducing polar organic groups (P=O and P=S) and electron-rich heterocyclic into the framework to obtain high carbon dioxide capture capacity. The estimated Brunauer-Emmett-Teller (BET) surface areas of these polymers are about 600 m(2) g(-1) and the highest CO2 uptake is 2.26 mmol g(-1) (1.0 bar/273 K). Interestingly, the polymer containing P=O groups shows greater CO2 capture capacity than that containing P=S groups at the same temperature. In addition, these polymers show high isosteric heats of CO2 adsorption (28.6 kJ mol(-1) ), which can be competitive with some nitrogen-rich networks. Therefore, these microporous polymers are promising candidates for carbon dioxide capture.

  8. Synthesis and characterization of polymer electrolyte membranes with controlled ion transport properties

    NASA Astrophysics Data System (ADS)

    Xu, Kui

    2011-12-01

    Ion-containing block copolymers hold promise as next-generation polymer electrolyte membrane (PEM) materials due to their capability to self-assemble into ordered nanostructures facilitating proton transport over a wide range of conditions. Ion-containing block copolymers, sulfonated poly(styrene- b-vinylidene fluoride-b-styrene), with varied degrees of sulfonation were synthesized. The synthetic strategy involved a new approach to chain-end functionalized poly(vinylidene fluoride) as a macro-initiator followed by atom transfer polymerization of styrene and sulfonation. Characterization of the polymers were extensively carried out by 1H and 19F nuclear magnetic resonance and Fouriertransform infrared spectroscopy, differential scanning calorimetry, and thermogravimetry analysis. Tapping mode atomic force microscopy and transmission electron microscopy were applied to study the phase separation and self-assembled morphology. Strong dependence of ion exchange capacity, water absorption, morphology and proton conductivity on the degree of sulfonation has been found. It has been observed that the conductivities of the block copolymers are considerably higher than the random copolymers of polystyrene and sulfonated polystyrene possessing similar ion exchange capacities. Copolymers of vinylidene fluoride and perfluoro(4-methyl-3,6-dioxane-7-ene) sulfonyl fluoride containing amino end-groups were synthesized for the first time. The prepared aminoterminated polymers underwent cross-linking reactions with 1,3,5-benzene triisocyanate to form proton conductive networks. The chain-end crosslinked fluoropolymer membranes exhibited excellent thermal, hydrolytic and oxidative stabilities. The ion exchange capacity, water uptake, the state of absorbed water, and transport properties of the membranes were found to be highly dependent upon the chemical composition of the copolymers. The cross-linked membranes showed extremely low methanol permeability, while maintaining high proton

  9. Preliminary study to characterize plastic polymers using elemental analyser/isotope ratio mass spectrometry (EA/IRMS).

    PubMed

    Berto, Daniela; Rampazzo, Federico; Gion, Claudia; Noventa, Seta; Ronchi, Francesca; Traldi, Umberto; Giorgi, Giordano; Cicero, Anna Maria; Giovanardi, Otello

    2017-06-01

    Plastic waste is a growing global environmental problem, particularly in the marine ecosystems, in consideration of its persistence. The monitoring of the plastic waste has become a global issue, as reported by several surveillance guidelines proposed by Regional Sea Conventions (OSPAR, UNEP) and appointed by the EU Marine Strategy Framework Directive. Policy responses to plastic waste vary at many levels, ranging from beach clean-up to bans on the commercialization of plastic bags and to Regional Plans for waste management and recycling. Moreover, in recent years, the production of plant-derived biodegradable plastic polymers has assumed increasing importance. This study reports the first preliminary characterization of carbon stable isotopes (δ(13)C) of different plastic polymers (petroleum- and plant-derived) in order to increase the dataset of isotopic values as a tool for further investigation in different fields of polymers research as well as in the marine environment surveillance. The δ(13)C values determined in different packaging for food uses reflect the plant origin of "BIO" materials, whereas the recycled plastic materials displayed a δ(13)C signatures between plant- and petroleum-derived polymers source. In a preliminary estimation, the different colours of plastic did not affect the variability of δ(13)C values, whereas the abiotic and biotic degradation processes that occurred in the plastic materials collected on beaches and in seawater, showed less negative δ(13)C values. A preliminary experimental field test confirmed these results. The advantages offered by isotope ratio mass spectrometry with respect to other analytical methods used to characterize the composition of plastic polymers are: high sensitivity, small amount of material required, rapidity of analysis, low cost and no limitation in black/dark samples compared with spectroscopic analysis.

  10. Synthesis, crystal structures and characterization of four coordination polymers based on 5-amino-2,4,6-triiodoisophthalic acid

    SciTech Connect

    Zhang Koulin; Chang Yan; Zhang Jingbo; Yuan Limin; Deng Ye; Diao Guowang; Ng, Seik Weng

    2011-05-15

    One homochiral 1D coordination polymer [Cu(ATIBDC)(2,2'-bipy)].3H{sub 2}O.CH{sub 3}OH (1) and three achiral 1D coordination polymers: [Cd(ATIBDC)(2,2'-bipy)(H{sub 2}O)].3H{sub 2}O (2), [Cd(ATIBDC)(phen)(H{sub 2}O)].4H{sub 2}O (3), and [Mn(ATIBDC)(phen){sub 2}].5H{sub 2}O (4) have been synthesized and characterized (H{sub 2}ATIBDC=5-amino-2,4,6-triiodoisophthalic acid, 2,2'-bipy=2,2'-bipyridine, and phen=1,10-phenanthroline). Extended high dimensional network architectures are further constructed with the help of weak secondary interactions, such as hydrogen bonding, aromatic stacking, and halogen bonding (C-I..{pi} and C-I...N/O). Complex 1 crystallizes in the monoclinic system with chiral space group P2(1) and exhibits a right-handed 2{sub 1} helical chain structure. The homochirality of 1 was confirmed by CD spectrum. Interestingly, two new configurations of decameric water cluster are found in 3 and 4. The acyclic tetrameric cluster (H{sub 2}O){sub 3}(CH{sub 3}OH) in 1 and (H{sub 2}O){sub 4} in 2 array into highly ordered helical infinite chains. Thermal stabilities of all the complexes have been studied. Solid state fluorescent properties of the Cd(II) complexes have been explored. -- Graphical abstract: The synthesis, crystal structures and characterization of one 1D homochiral coordination polymer and three achiral 1D coordination polymers with 5-amino-2,4,6-triiodoisophthalic acid (H{sub 2}ATIBDC) are reported. Display Omitted highlights: > Four 1D coordination polymers with 5-amino-2,4,6-triiodoisophthalate are reported. > The halogen bonds play important roles in the supramolecular assembly. > Solid state fluorescent properties of the Cd(II) complexes are explored.

  11. Characterization of a metal-chelating substance in coffee.

    PubMed

    Takenaka, Makiko; Sato, Naoko; Asakawa, Hiromi; Wen, Xu; Murata, Masatsune; Homma, Seiichi

    2005-01-01

    A metal-chelating substance in brewed coffee was separated and characterized by its chemical structure. This substance was a brown polymer. The contents of sugars, amino acids and phenolics in the substance were evaluated. This polymer contained small amounts of sugars and amino acids in its partial structure. After being decomposed by alkaline fusion, the decomposition products were identified by HPLC and GC-MS. Several phenolics were detected in the decomposed products. To characterize this substance, various types of model compounds were prepared by roasting chlorogenic acid, sucrose, and (or) protein with cellulose powder. Among these model compounds, the polymer-forming ability was highest in the model prepared from all four of materials, but the metal-chelating ability was the highest in the model prepared from chlorogenic acid and cellulose. These results suggest that this metal-chelating substance was a melanoidin-like polymer formed by the decomposition and polymerization of sugars, amino acids and phenolics.

  12. Synthesis and characterization of biodegradable peptide-based polymers prepared by microwave-assisted click chemistry.

    PubMed

    van Dijk, Maarten; Nollet, Maria L; Weijers, Pascal; Dechesne, Annemarie C; van Nostrum, Cornelus F; Hennink, Wim E; Rijkers, Dirk T S; Liskamp, Rob M J

    2008-10-01

    In this study, the microwave-assisted copper(I)-catalyzed 1,3-dipolar cycloaddition reaction was used to synthesize peptide triazole-based polymers from two novel peptide-based monomers: azido-phenylalanyl-alanyl-lysyl-propargyl amide (1) and azido-phenylalanyl-alanyl-glycolyl-lysyl-propargyl amide (2). The selected monomers have sites for enzymatic degradation as well as for chemical hydrolysis to render the resulting polymer biodegradable. Depending on the monomer concentration in DMF, the molecular mass of the polymers could be tailored between 4.5 and 13.9 kDa (corresponding with 33-100 amino acid residues per polymer chain). As anticipated, both polymers can be enzymatically degraded by trypsin and chymotrypsin, whereas the ester bond in the polymer of 2 undergoes chemical hydrolysis under physiological conditions, as was shown by a ninhydrin-based colorimetric assay and MALDI-TOF analysis. In conclusion, the microwave-assisted copper(I)-catalyzed 1,3-dipolar cycloaddition reaction is an effective tool for synthesizing biodegradable peptide polymers, and it opens up new approaches toward the synthesis of (novel) designed biomedical materials.

  13. Synthesis and characterization of thermally stable and/or conductive polymers

    SciTech Connect

    Gajiwala, H.M.

    1992-01-01

    Eight new thermally stable polyimides were synthesized from two tricyclic heterocyclic diamines: thionine which has a phenothiazine moiety and proflavine which has an acridine unit. The polymerization reactions were optimized with respect to solvents, reaction time, reaction temperature, solid contents, etc., and their structure property relationships were studied. All these soluble polyimides have nice film forming properties. One of the polyimides containing the acridine moiety, appears to have a tendency to form a liquid crystalline state when its solution is passed through a fine capillary. All of these polyimides were thermally stable in air up to 500-550[degrees]C and up to 600[degrees]C in a nitrogen atmosphere. They have refractive indices in the range of 1.65 to 1.85 and have relatively low value of permittivity. Two other thermally stable polymers, viz., polybenzimidazole and the ladder polymer having the phenazine moiety in the backbone were also synthesized. For these polymerization reactions, tetraamino derivative of phenazine was synthesized from the commercially available diamino, dinitro derivative of benzene. The polybenzimidazole was prepared via the azomethine pathway. This polymer had an intrinsic viscosity of 0.94 in methanesulfonic acid. The nice film forming polybenzimidazole polymer was found to be thermally stable up to 400[degrees]C. The ladder type of a polymer was synthesized by condensation polymerization between tetraaminophenazine and dihydroxybenzophenone in polyphosphoric acid at an elevated temperature. The completely conjugated ladder polymer was found to be semiconducting on doping with iodine. This polymer was highly crystalline as demonstrated by its X-ray diffraction pattern. A morphology study of the polymer indicated that the material has a tendency to form dendritic crystals. The polymer was thermally stable up to about 400[degrees]C in air.

  14. Synthesis and characterization of polymer brushes for controlled adsorption of proteins

    NASA Astrophysics Data System (ADS)

    Hoy, Olha

    Performance of biomedical devices to a large extent depends on the interactions between the device surface and the biological liquids/protein molecules. To achieve controllable interactions between the device and biomolecules and still retain the required mechanical strength on the whole, modification of the surface is often done. In the present study surface properties were modified through a polymer brush approach. After the modification, surfaces gain tunability toward protein adsorption. Mixed polymer brushes consisting of protein repelling and protein attractive components were used, with a "grafting to" method employed for the synthesis of polymer layers. First, poly(ethylene glycol), the protein repelling component of the mixed polymer brush, was tethered to the surface. Then, polyacrylic acid-b-polystyrene (the protein attractive component) was grafted on top of the previous layer. As one part of this study, the temperature dependence of grafting of the mixed brush components was studied. Surface morphology and surface properties of the mixed polymer brush were altered by treating the brush with different organic solvents. Changes in surface morphology and properties resulting from the solvent treatment were studied in dry conditions and in aqueous media. Hydrophobic interactions of the mixed polymer brush in different pH environments were also estimated. Synthesized mixed polymer brushes demonstrated a clear dependency between the external stimuli applied to the brush and the amount of the protein adsorbed onto the brush surface, allowing an effective control of protein adsorption. Attraction forces between the protein molecules and surface of he mixed polymer brush were measured using AFM and these supported the findings from the protein adsorption studies. 2-D molecular imprinting of the polymer brush approach was used to synthesize a surface with controlled positioning of the protein molecules on the surface. Protein adsorption onto the surface of the

  15. Furan-functionalized co-polymers for targeted drug delivery: characterization, self-assembly and drug encapsulation.

    PubMed

    Shi, Meng; Shoichet, Molly S

    2008-01-01

    We have previously reported furan-maleimide Diels-Alder chemistry as a new methodology to couple maleimide-modified antibodies on furan-functionalized polymeric carriers in the preparation of immuno-nanoparticles for targeted drug delivery. In this report, we focus on the characterization, self-assembly behavior and drug encapsulation of two types of furan-functionalized co-polymers: poly(2-methyl, 2-carboxytrimethylene carbonate-co-D,L-lactide)-furan (poly(TMCC-co-LA)-furan) and poly(2-methyl, 2-carboxytrimethylene carbonate-co-D,L-lactide)-graft-poly(ethylene glycol)-furan (poly(TMCC-co-LA)-g-PEG-furan). The co-polymers were synthesized by modifying the carboxylic acid groups on the poly(TMCC-co-LA) backbone by either furfurylamine or PEG-furan to generate either linear co-polymers of poly(TMCC-co-LA)-furan with furan pendant groups or graft co-polymers of poly(TMCC-co-LA)-g-PEG-furan with furan-terminated PEG grafts, respectively. Using a membrane dialysis method, both of the co-polymers were self-assembled into nanoparticles in aqueous environments driven by the hydrophobic association among polymer chains. The hydrophobic domains in the nanoparticles were confirmed by the incorporation of pyrene molecules and the critical aggregation concentrations were determined to be approximately 5 x 10(-5) mM for poly(TMCC-co-LA)-furan and 2 x 10(-4) mM for poly(TMCC-co-LA)-g-PEG-furan. By the addition of borate buffer in the organic solvent used to dissolve the co-polymers in the dialysis procedure, we were able to control the size of the nanoparticles: 54-169 nm for poly(TMCC-co-LA)-furan and 28-283 nm for poly(TMCC-co-LA)-g-PEG-furan. This unique feature can be explained by the ionization of carboxylic acid groups along the co-polymer backbone. A hydrophobic anticancer drug, doxorubicin (DOX), was encapsulated within the nanoparticles, with the larger size nanoparticles incorporating greater amounts of DOX. Combining the strategy of antibody-mediated targeting, these

  16. Polydisperse methyl β-cyclodextrin–epichlorohydrin polymers: variable contact time 13C CP-MAS solid-state NMR characterization

    PubMed Central

    Mallard, Isabelle; Baudelet, Davy; Castiglione, Franca; Ferro, Monica; Panzeri, Walter; Ragg, Enzio

    2015-01-01

    Summary The polymerization of partially methylated β-cyclodextrin (CRYSMEB) with epichlorohydrin was carried out in the presence of a known amount of toluene as imprinting agent. Three different preparations (D1, D2 and D3) of imprinted polymers were obtained and characterized by solid-state 13C NMR spectroscopy under cross-polarization magic angle spinning (CP-MAS) conditions. The polymers were prepared by using the same synthetic conditions but with different molar ratios of imprinting agent/monomer, leading to morphologically equivalent materials but with different absorption properties. The main purpose of the work was to find a suitable spectroscopic descriptor accounting for the different imprinting process in three homogeneous polymeric networks. The polymers were characterized by studying the kinetics of the cross-polarization process. This approach is based on variable contact time CP-MAS spectra, referred to as VCP-MAS. The analysis of the VCP-MAS spectra provided two relaxation parameters: T CH (the CP time constant) and T 1ρ (the proton spin-lattice relaxation time in the rotating frame). The results and the analysis presented in the paper pointed out that T CH is sensitive to the imprinting process, showing variations related to the toluene/cyclodextrin molar ratio used for the preparation of the materials. Conversely, the observed values of T 1ρ did not show dramatic variations with the imprinting protocol, but rather confirmed that the three polymers are morphologically similar. Thus the combined use of T CH and T 1ρ can be helpful for the characterization and fine tuning of imprinted polymeric matrices. PMID:26877800

  17. Polydisperse methyl β-cyclodextrin-epichlorohydrin polymers: variable contact time (13)C CP-MAS solid-state NMR characterization.

    PubMed

    Mallard, Isabelle; Baudelet, Davy; Castiglione, Franca; Ferro, Monica; Panzeri, Walter; Ragg, Enzio; Mele, Andrea

    2015-01-01

    The polymerization of partially methylated β-cyclodextrin (CRYSMEB) with epichlorohydrin was carried out in the presence of a known amount of toluene as imprinting agent. Three different preparations (D1, D2 and D3) of imprinted polymers were obtained and characterized by solid-state (13)C NMR spectroscopy under cross-polarization magic angle spinning (CP-MAS) conditions. The polymers were prepared by using the same synthetic conditions but with different molar ratios of imprinting agent/monomer, leading to morphologically equivalent materials but with different absorption properties. The main purpose of the work was to find a suitable spectroscopic descriptor accounting for the different imprinting process in three homogeneous polymeric networks. The polymers were characterized by studying the kinetics of the cross-polarization process. This approach is based on variable contact time CP-MAS spectra, referred to as VCP-MAS. The analysis of the VCP-MAS spectra provided two relaxation parameters: T CH (the CP time constant) and T 1ρ (the proton spin-lattice relaxation time in the rotating frame). The results and the analysis presented in the paper pointed out that T CH is sensitive to the imprinting process, showing variations related to the toluene/cyclodextrin molar ratio used for the preparation of the materials. Conversely, the observed values of T 1ρ did not show dramatic variations with the imprinting protocol, but rather confirmed that the three polymers are morphologically similar. Thus the combined use of T CH and T 1ρ can be helpful for the characterization and fine tuning of imprinted polymeric matrices.

  18. Structural characterization of a polymer substituted fullerene (flagellene) by small angle neutron scattering

    SciTech Connect

    Affholter, K.A.; Bunick, G.J.; Wignall, G.D.; Desimone, J.M.; Hunt, M.O. Jr.; Menceloglu, Y.Z.; Samulski, E.T.

    1994-12-31

    Small-angle neutron scattering (SANS) can structurally characterize fullerenes in solvents with strong SANS contrast (e.g. CS{sub 2}). Deuterated solvents (e.g. toluene-d{sub 8}) have a high scattering length density (SLD), which is close to that of C{sub 60} and C{sub 70} moieties. Hence, there is virtually no SANS contrast with the solvent and these particles are practically ``invisible`` in such media. On the other hand, the negative scattering length of hydrogen means that the SLD of H{sup 1}-containing materials is much lower, so they have strong contrast with toluene-d{sub 8}. Thus, SANS makes it possible to study the size and shapes of modified buckyballs such as the polymer-substituted fullerenes, or flagellenes. These consist of C{sub 60} cores to which 1-4 polystryene chains (with a molecular weight, MW {approx_equal} 2000) are attached. The extrapolated cross section at zero angle of scatter [d{Sigma}/d{Omega}(0)] is a function of the number of pendant chains, so SANS can be used to assess the number of ``arms`` which are covalently attached to the fullerene ``sphere.`` Close agreement ({plus_minus}4%) between measured and calculated values of d{Sigma}/d{Omega}(0) along with independent estimates of the radius of gyration (R{sub g}) and second virial coefficient (A{sub 2}) for a calibration linear polystyrene sample serves as a cross check on the validity of this methodology.

  19. Biosynthesis and characterization of silver nanoparticles prepared from two novel natural precursors by facile thermal decomposition methods

    NASA Astrophysics Data System (ADS)

    Goudarzi, Mojgan; Mir, Noshin; Mousavi-Kamazani, Mehdi; Bagheri, Samira; Salavati-Niasari, Masoud

    2016-09-01

    In this work, two natural sources, including pomegranate peel extract and cochineal dye were employed for the synthesis of silver nanoparticles. The natural silver complex from pomegranate peel extract resulted in nano-sized structures through solution-phase method, but this method was not efficient for cochineal dye-silver precursor and the as-formed products were highly agglomerated. Therefore, an alternative facile solid-state approach was investigated as for both natural precursors and the results showed successful production of well-dispersed nanoparticles with narrow size distribution for cochineal dye-silver precursor. The products were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray microanalysis (EDX), and Transmission Electron Microscopy (TEM).

  20. Biosynthesis and characterization of silver nanoparticles prepared from two novel natural precursors by facile thermal decomposition methods

    PubMed Central

    Goudarzi, Mojgan; Mir, Noshin; Mousavi-Kamazani, Mehdi; Bagheri, Samira; Salavati-Niasari, Masoud

    2016-01-01

    In this work, two natural sources, including pomegranate peel extract and cochineal dye were employed for the synthesis of silver nanoparticles. The natural silver complex from pomegranate peel extract resulted in nano-sized structures through solution-phase method, but this method was not efficient for cochineal dye-silver precursor and the as-formed products were highly agglomerated. Therefore, an alternative facile solid-state approach was investigated as for both natural precursors and the results showed successful production of well-dispersed nanoparticles with narrow size distribution for cochineal dye-silver precursor. The products were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray microanalysis (EDX), and Transmission Electron Microscopy (TEM). PMID:27581681

  1. Development and characterization of poly(1-vinylpyrrolidone-co-vinyl acetate) copolymer based polymer electrolytes.

    PubMed

    Sa'adun, Nurul Nadiah; Subramaniam, Ramesh; Kasi, Ramesh

    2014-01-01

    Gel polymer electrolytes (GPEs) are developed using poly(1-vinylpyrrolidone-co-vinyl acetate) [P(VP-co-VAc)] as the host polymer, lithium bis(trifluoromethane) sulfonimide [LiTFSI] as the lithium salt and ionic liquid, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [EMImTFSI] by using solution casting technique. The effect of ionic liquid on ionic conductivity is studied and the optimum ionic conductivity at room temperature is found to be 2.14 × 10(-6) S cm(-1) for sample containing 25 wt% of EMImTFSI. The temperature dependence of ionic conductivity from 303 K to 353 K exhibits Arrhenius plot behaviour. The thermal stability of the polymer electrolyte system is studied by using thermogravimetric analysis (TGA) while the structural and morphological properties of the polymer electrolyte is studied by using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction analysis (XRD), respectively.

  2. Bismaleimide/Preceramic Polymer Blends for Hybrid Material Transition Regions. Part 1. Processing and Characterization (Postprint)

    DTIC Science & Technology

    2014-01-01

    Case Number: 88ABW-2012-4313; Clearance Date: 08 Aug 2012. Journal article published in High Performance Polymers, 25(4), 363-376 (2013). © 2012 Sage...thermal properties, and rheology of the blends. Preparation of hot-melt blends Two types of samples were prepared. The first group was mixed and then...siloxanes to silicon carbide. Chem Mater 1992; 4: 1313–1323. 12. Elias L, Fenouillot F, Majeste JC, et al. Morphology and rheology of immiscible polymer

  3. Unusually conductive carbon-inherently conducting polymer (ICP) composites: Synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Bourdo, Shawn Edward

    Two groups of materials that have recently come to the forefront of research initiatives are carbon allotropes, especially nanotubes, and conducting polymers-more specifically inherently conducting polymers. The terms conducting polymers and inherently conducting polymers sometimes are used interchangeably without fully acknowledging a major difference in these terms. Conducting polymers (CPs) and inherently conducting polymers (ICPs) are both polymeric materials that conduct electricity, but the difference lies in how each of these materials conducts electricity. For CPs of the past, an electrically conductive filler such as metal particles, carbon black, or graphite would be blended into a polymer (insulator) allowing for the CP to carry an electric current. An ICP conducts electricity due to the intrinsic nature of its chemical structure. The two materials at the center of this research are graphite and polyaniline. For the first time, a composite between carbon allotropes (graphite) and an inherently conducting polymer (PANI) has exhibited an electrical conductivity greater than either of the two components. Both components have a plethora of potential applications and therefore the further investigation could lead to use of these composites in any number of technologies. Touted applications that use either conductive carbons or ICPs exist in a wide range of fields, including electromagnetic interference (EMI) shielding, radar evasion, low power rechargeable batteries, electrostatic dissipation (ESD) for anti-static textiles, electronic devices, light emitting diodes (LEDs), corrosion prevention, gas sensors, super capacitors, photovoltaic cells, and resistive heating. The main motivation for this research has been to investigate the connection between an observed increase in conductivity and structure of composites. Two main findings have resulted from the research as related to the observed increase in conductivity. The first was the structural evidence from

  4. Thermal Decomposition of Radiation-Damaged Polystyrene

    SciTech Connect

    J Abrefah GS Klinger

    2000-09-26

    The radiation-damaged polystyrene material (''polycube'') used in this study was synthesized by mixing a high-density polystyrene (''Dylene Fines No. 100'') with plutonium and uranium oxides. The polycubes were used on the Hanford Site in the 1960s for criticality studies to determine the hydrogen-to-fissile atom ratios for neutron moderation during processing of spent nuclear fuel. Upon completion of the studies, two methods were developed to reclaim the transuranic (TRU) oxides from the polymer matrix: (1) burning the polycubes in air at 873 K; and (2) heating the polycubes in the absence of oxygen and scrubbing the released monomer and other volatile organics using carbon tetrachloride. Neither of these methods was satisfactory in separating the TRU oxides from the polystyrene. Consequently, the remaining polycubes were sent to the Hanford Plutonium Finishing Plant (PFP) for storage. Over time, the high dose of alpha and gamma radiation has resulted in a polystyrene matrix that is highly cross-linked and hydrogen deficient and a stabilization process is being developed in support of Defense Nuclear Facility Safety Board Recommendation 94-1. Baseline processes involve thermal treatment to pyrolyze the polycubes in a furnace to decompose the polystyrene and separate out the TRU oxides. Thermal decomposition products from this degraded polystyrene matrix were characterized by Pacific Northwest National Laboratory to provide information for determining the environmental impact of the process and for optimizing the process parameters. A gas chromatography/mass spectrometry (GC/MS) system coupled to a horizontal tube furnace was used for the characterization studies. The decomposition studies were performed both in air and helium atmospheres at 773 K, the planned processing temperature. The volatile and semi-volatile organic products identified for the radiation-damaged polystyrene were different from those observed for virgin polystyrene. The differences were in the

  5. Synthesis and Characterization of Thermally Stable Photocurable Polymer with Cyclohexane Moiety.

    PubMed

    Kim, Dong Mm; Yu, Seong Hun; Lee, Jun Young

    2016-03-01

    Photocurable polymers with high transparency and thermal stability were synthesized by reaction between a commercial epoxy resin (NC9110) containing cyclohexane moiety and various kinds of cinnamic acids such as trans-cinnamic acid (CA), 3-hydroxy-trans-cinnamic acid (HCA) and 4-methoxy-trans-cinnamic acid (MCA). The photocurable polymers were synthesized with equal equivalent weight ratio of epoxy and cinnamate group. The chemical structures of the synthesized polymers were confirmed by 1H-NMR and FT-IR spectroscopies. Optical transmittance and thermal stability of the photocured polymers were investigated using UV-Visible spectroscopy and thermogravimetric analysis (TGA), respectively. It was confirmed that the polymers could form thin films with very smooth surface and could be efficiently cured by UV irradiation. It was also found that the polymer after curing showed a good thermal stability and optical transmittance. There was no significant transmittance change after heat treatment at 250 degrees C for 1 h and showed no noticeable weight loss up to 360 degrees C.

  6. Characterization and Mechanism for the Protection of Photolytic Decomposition of N-Halamine Siloxane Coatings by Titanium Dioxide.

    PubMed

    Liu, Ying; Li, Jing; Li, Lin; McFarland, Stuart; Ren, Xuehong; Acevedo, Orlando; Huang, T S

    2016-02-10

    N-Halamine antibacterial materials have superior inactivation activities due to oxidative chlorine species. However, N-Cl bonds and bonds between N-halamine and substrates often decompose rapidly under UV irradiation, leading to unrecoverable loss of antimicrobial activity. In this study, titanium dioxide was covalently bonded onto N-halamine siloxane poly[5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin] (PSPH) via a sol-gel process. Experimental testing of the chlorinated cotton fabrics treated with TiO2/PSPH demonstrated that the residual oxidative chlorine in cotton-TiO2/PSPH-Cl was still effective for inactivating bacteria after 50 washing cycles and under UV light irradiation for 24 h. Quantum mechanical calculations found that TiO2 improves the UV stability of the PSPH-Cl system by increasing the activation barrier of the C-Si scission reaction responsible for the loss of the biocidal hydantoin moiety. SEM, XPS and FTIR spectra were used to characterize the coated cotton samples. Cotton-TiO2/PSPH-Cl samples exhibited good antibacterial activity against Staphylococcus aureus (ATCC 6538) and Escherichia coli O157:H7 (ATCC 43895). The storage stability and washing stability of treated cotton fabrics were also investigated.

  7. Synthesis, spectroscopic characterization, electrochemical behaviour and thermal decomposition studies of some transition metal complexes with an azo derivative

    NASA Astrophysics Data System (ADS)

    Sujamol, M. S.; Athira, C. J.; Sindhu, Y.; Mohanan, K.

    2010-01-01

    Complexes of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) with a novel heterocyclic azo derivative, formed by coupling diazotized 2-amino-3-carbethoxy-4,5-dimethylthiophene with acetylacetone were synthesized and characterized on the basis of elemental analyses, molar conductance, magnetic susceptibility measurements, UV-vis, IR, 1H NMR and EPR spectral data. Spectral studies revealed that the ligand existed in an internally hydrogen bonded azo-enol form rather than the keto-hydrazone form and coordinated to the metal ion in a tridentate fashion. Analytical data revealed that all the complexes exhibited 1:1 metal-ligand ratio. On the basis of electronic spectral data and magnetic susceptibility measurements, suitable geometry was proposed for each complex. The nickel(II) complex has undergone facile transesterification reaction when refluxed in methanol for a long period. The ligand and the copper(II) complex were subjected to X-ray diffraction study. The electrochemical behaviour of copper(II) complex was investigated by cyclic voltammetry. The thermal behaviour of the same complex was also examined by thermogravimetry.

  8. Synthesis, spectroscopic characterization, electrochemical behaviour and thermal decomposition studies of some transition metal complexes with an azo derivative.

    PubMed

    Sujamol, M S; Athira, C J; Sindhu, Y; Mohanan, K

    2010-01-01

    Complexes of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) with a novel heterocyclic azo derivative, formed by coupling diazotized 2-amino-3-carbethoxy-4,5-dimethylthiophene with acetylacetone were synthesized and characterized on the basis of elemental analyses, molar conductance, magnetic susceptibility measurements, UV-vis, IR, (1)H NMR and EPR spectral data. Spectral studies revealed that the ligand existed in an internally hydrogen bonded azo-enol form rather than the keto-hydrazone form and coordinated to the metal ion in a tridentate fashion. Analytical data revealed that all the complexes exhibited 1:1 metal-ligand ratio. On the basis of electronic spectral data and magnetic susceptibility measurements, suitable geometry was proposed for each complex. The nickel(II) complex has undergone facile transesterification reaction when refluxed in methanol for a long period. The ligand and the copper(II) complex were subjected to X-ray diffraction study. The electrochemical behaviour of copper(II) complex was investigated by cyclic voltammetry. The thermal behaviour of the same complex was also examined by thermogravimetry.

  9. On symmetric decompositions of positive operators

    NASA Astrophysics Data System (ADS)

    Anastasia Jivulescu, Maria; Nechita, Ion; Găvruţa, Paşc

    2017-04-01

    We present results concerning decompositions of positive operators acting on finite-dimensional Hilbert spaces. Our motivation is the study of a generalized version of the SIC–POVM problem, which has applications to Quantum Information Theory. We relax some of the conditions in the SIC–POVM setting (the elements sum up to the identity, resp. the elements have unit rank), and we focus on equiangular decompositions (the elements of the decomposition should have the same length, and pairs of distinct elements should have constant angles). We characterize all such decompositions, comparing our results with the case of SIC–POVMs. We also generalize some existing Welch-type inequalities.

  10. Potential approaches to the spectroscopic characterization of high performance polymers exposed to energetic protons and heavy ions

    NASA Technical Reports Server (NTRS)

    Suleman, Naushadalli K.

    1991-01-01

    A potential limitation to human activity on the lunar surface or in deep space is the exposure of the crew to unacceptably high levels of penetrating space radiations. The radiations of most concerns for such missions are high-energy protons emitted during solar flares, and galactic cosmic rays which are high-energy ions ranging from protons to iron. The development of materials for effective shielding from energetic space radiations will clearly require a greater understanding of the underlying mechanisms of radiation-induced damage in bulk materials. This can be accomplished in part by the detailed spectroscopic characterization of bulk materials that were exposed to simulated space radiations. An experimental data base thus created can then be used in conjunction with existing radiation transport codes in the design and fabrication of effective radiation shielding materials. Electron Paramagnetic Resonance Spectroscopy was proven very useful in elucidating radiation effects in polymers (high performance polymers are often an important components of structural composites).

  11. Characterization of nanocellulose reinforced semi-interpenetrating polymer network of poly(vinyl alcohol) & polyacrylamide composite films.

    PubMed

    Mandal, Arup; Chakrabarty, Debabrata

    2015-12-10

    Semi-interpenetrating polymer network (semi-IPN) of poly(vinyl alcohol)/polyacrylamide was reinforced with various doses of nanocellulose. The different composite films thus prepared were characterized with respect to their mechanical, thermal, morphological and barrier properties. The composite film containing 5 wt.% of nanocellulose showed the highest tensile strength. The semi-interpenetrating polymer network of poly(vinyl alcohol)/polyacrylamide; and its various composites with nanocellulose were almost identical in their thermal stability. Each of the composites however exhibited much superior stability with respect to the linear poly(vinyl alcohol) and crosslinked polyacrylamide. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies exhibited phase separated morphology where agglomerates of nanocellulose were found to be dispersed in the matrix of the semi-IPN. The moisture vapor transmission rate (MVTR) was the lowest for the film containing 5 wt.% of nanocellulose.

  12. Synthesis and characterization of perfluorinated sulfonimide copolymers as polymer electrolyte membranes

    NASA Astrophysics Data System (ADS)

    Zhou, Shuang

    Ionomers for polymer electrolyte membranes in fuel cell applications were developed utilizing the acidic bis(perfluoromethyl sulfonyl) imide functional group. Perfluorinated vinyl ether sulfonimide monomers CF2=CFOCF 2CF(CF3)O(CF2)2SO2N(Na)SO 2CF3 (1), CF2=CFOCF2CF(CF 3)O(CF2)2SO2N(Na)SO2(CF 2)4SO2N(Na)CF3 (2), CF 2=CFOCF2CF(CF3)O(CF2)2SO 2N(Na)SO2(CF2)6SO2N(Na)CF 3 (3) and CF2=CFOCF2CF(CF3)O(CF2) 2SO2N(Na)SO2(CF2)2O(CF 2)2SO2N(Na)CF3 (4) were synthesized through multiple steps. The complete coupling reaction between the water sensitive CF3SO 2N(Na)Si(CH3)3 and the bromine-protected Dupont monomer BrCF2CFBrOCF2CF(CF3)O(CF2) 2SO2F is an important step to incorporate the sulfonimide group into the monomer 1. Bis(fluorosulfonyl) perfluoroalkanes FSO2RfSO2F (Rf = -(CF 2)4-, -(CF2)6- and -(CF 2)2O(CF2)2-) were used to introduce multifunctional sulfonimides into monomers 2, 3 and 4. Disulfonyl fluoride compounds were reacted with CF 3SO2N(Na)SiMe3 affording the unsymmetrical sulfonyl fluoride intermediates CF3SO2N(Na)SO2R fSO2F. After the transformation of -SO2F into -SO2N(Na)Si(CH3), the coupling reaction of the silyl compounds with BrCF2CFBrOCF2CF(CF3)O(CF 2)2SO2F followed by debromination gave the final products 2, 3 and 4. Copolymers of the sulfonimide monomers with tetrafluoroethylene (TFE) were produced by semi-batch free-radical emulsion copolymerizations. The perflurinated vinyl ether sulfonimide, TFE, the redox initiator pair (NH4) 2S2O8/NaHSO3, the emulsifier C 7F15COONH4 and the buffer NaH2PO 4/Na2HPO4 were mixed in a stirred Parr autoclave at 10°C. During the copolymerization, TFE pressure and the sulfonimide monomer concentration were kept nearly constant in the reaction system to generate copolymers with acidic groups randomly distributed in the polymer chains. Copolymerization conditions were optimized through variations of some important reaction parameters such as the initiator concentration, TFE pressure, the sulfonimide monomer concentration and the

  13. Polymer surface functionalities that control human embryoid body cell adhesion revealed by high throughput surface characterization of combinatorial material microarrays.

    PubMed

    Yang, Jing; Mei, Ying; Hook, Andrew L; Taylor, Michael; Urquhart, Andrew J; Bogatyrev, Said R; Langer, Robert; Anderson, Daniel G; Davies, Martyn C; Alexander, Morgan R

    2010-12-01

    High throughput materials discovery using combinatorial polymer microarrays to screen for new biomaterials with new and improved function is established as a powerful strategy. Here we combine this screening approach with high throughput surface characterization (HT-SC) to identify surface structure-function relationships. We explore how this combination can help to identify surface chemical moieties that control protein adsorption and subsequent cellular response. The adhesion of human embryoid body (hEB) cells to a large number (496) of different acrylate polymers synthesized in a microarray format is screened using a high throughput procedure. To determine the role of the polymer surface properties on hEB cell adhesion, detailed HT-SC of these acrylate polymers is carried out using time of flight secondary ion mass spectrometry (ToF SIMS), X-ray photoelectron spectroscopy (XPS), pico litre drop sessile water contact angle (WCA) measurement and atomic force microscopy (AFM). A structure-function relationship is identified between the ToF SIMS analysis of the surface chemistry after a fibronectin (Fn) pre-conditioning step and the cell adhesion to each spot using the multivariate analysis technique partial least squares (PLS) regression. Secondary ions indicative of the adsorbed Fn correlate with increased cell adhesion whereas glycol and other functionalities from the polymers are identified that reduce cell adhesion. Furthermore, a strong relationship between the ToF SIMS spectra of bare polymers and the cell adhesion to each spot is identified using PLS regression. This identifies a role for both the surface chemistry of the bare polymer and the pre-adsorbed Fn, as-represented in the ToF SIMS spectra, in controlling cellular adhesion. In contrast, no relationship is found between cell adhesion and wettability, surface roughness, elemental or functional surface composition. The correlation between ToF SIMS data of the surfaces and the cell adhesion demonstrates

  14. Isolation, characterization, and evaluation of Cassia fistula Linn. seed and pulp polymer for pharmaceutical application

    PubMed Central

    Killedar, Suresh G; Nale, Ashwini B; more, Harinath N; Nadaf, Sameer J; Pawar, Anuja A; Tamboli, Umarfarukh S

    2014-01-01

    Introduction: Present work, is an effort toward exploring the potential of Cassia fistula Linn. seed gum as an extended release polymer and laxative. While, C. fistula pulp polymer has evaluated as suspending agent. Materials and Methods: For extended release application, total five batches (F1-F5) were prepared by varying the ratio of drug:polymer as 1:1, 1:2, 1:3, 1:4, and 1:5, respectively. The granules were prepared by wet granulation method and further evaluated for micromeritic properties such as angle of repose (θ), Carr's compressibility index (CCI), and Hausner's ratio. Further compacts were evaluated by hardness, thickness, swelling index, in-vitro dissolution, and so on. Laxative activity was evaluated by administration of seed polymer (100 mg/kg) alone or in combination with bisacodyl (2.5 mg/kg) in 1% Tween 80. Zinc oxide suspension was prepared by varying the concentration of C. fistula pulp polymer and compared with suspension made by use of tragacanth, sodium carboxymethyl cellulose and bentonite. Results: Result showed that granules were free flowing, while the compact extended the drug release up to 10 h (72.84 ± 0.98; batch F5) and followed Higuchi matrix release kinetics. This extended release might be due to the formation of polyelectrolyte complex because of gluco-mannose in seed gum. Result of in-vivo laxative activity showed that seed polymer reduced faeces weight after 24 h compared to control (P < 0.01). Conclusions: Pulp polymer showed good sedimentation volume, but alone fails to stabilize the suspension for a longer period, so it could be useful in combination with other suspending agents and can be useful as novel excipient. PMID:25426443

  15. Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

    PubMed Central

    Hess, Allison E.; Potter, Kelsey A.; Tyler, Dustin J.; Zorman, Christian A.; Capadona, Jeffrey R.

    2013-01-01

    Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, each offering its own advantages and shortcomings5,6. Most prominently, due to the microscale device dimensions, a high modulus is required to facilitate implantation into living tissue. Conversely, the stiffness of the device should match the surrounding tissue to minimize induced local strain7-9. Therefore, we recently developed a new class of bio-inspired materials to meet these requirements by responding to environmental stimuli with a change in mechanical properties10-14. Specifically, our poly(vinyl acetate)-based nanocomposite (PVAc-NC) displays a reduction in stiffness when exposed to water and elevated temperatures (e.g. body temperature). Unfortunately, few methods exist to quantify the stiffness of materials in vivo15, and mechanical testing outside of the physiological environment often requires large samples inappropriate for implantation. Further, stimuli-responsive materials may quickly recover their initial stiffness after explantation. Therefore, we have developed a method by which the mechanical properties of implanted microsamples can be measured ex vivo, with simulated physiological conditions maintained using moisture and temperature control13,16,17. To this end, a custom microtensile tester was designed to accommodate microscale samples13,17 with widely-varying Young's moduli (range of 10 MPa to 5 GPa). As our interests are in the application of PVAc-NC as a biologically-adaptable neural probe substrate, a tool capable of mechanical characterization of samples at the microscale was necessary. This tool was adapted to provide humidity and temperature control, which minimized sample drying and cooling17. As a result, the mechanical characteristics of the explanted sample closely reflect those of the sample just prior to explantation. The overall goal of this method is to quantitatively assess

  16. Non-Destructive Characterization of Polymer/Metal Interphases Using Surface-Enhanced Raman Scattering

    DTIC Science & Technology

    1990-06-01

    acetylphenylhydrazine, and cumene hydroperoxide were similar to SERS spectra of saccharin and to normal Raman spectra of the sodium salt of saccharin... salts are important factors in the curing reaction of the adhesive since metal ions catalyze decomposition of the hydroperoxide to form radicals that... hydroperoxide (CHP), acetylphenylhydrazine (APH), and saccharin. SERS spectra obtained from films of the adhesive spin-coated onto silver island films

  17. Star Polymers.

    PubMed

    Ren, Jing M; McKenzie, Thomas G; Fu, Qiang; Wong, Edgar H H; Xu, Jiangtao; An, Zesheng; Shanmugam, Sivaprakash; Davis, Thomas P; Boyer, Cyrille; Qiao, Greg G

    2016-06-22

    Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings.

  18. Fluorescence anisotropy sensor and its application to polymer processing and characterization

    NASA Astrophysics Data System (ADS)

    Bur, Anthony J.; Roth, Steven C.; Thomas, Charles L.

    2000-03-01

    An optical sensor containing polarizing optical components has been constructed to monitor fluorescence anisotropy during polymer processing and to carry out remote sensing of polymer products doped with fluorescent dyes. The sensor is a compact unit that is used to polarize incident excitation light as well as to analyze the polarization of generated fluorescent light. Optical fibers are used to carry light between the sensor head and the light source and detecting equipment. The anisotropy measurement yields information about the orientation of a fluorescent dye molecule that has been doped into polymer matrix. Fluorescent dyes that have geometrical asymmetry in their molecular structure are used. Experiments are described for which the sensor is positioned in line during extrusion, during specimen extension, and where the sensor is used to carry out area scans of films and sheets. Measurements were made on polyethylene, polyethylene terephthalate, and polybutadiene resins that contained a low concentration of fluorescent dye.

  19. Characterization of coplanar poled electro optic polymer films for Si-photonic devices with multiphoton microscopy

    SciTech Connect

    Himmelhuber, R. Mehravar, S. S.; Herrera, O. D.; Demir, V.; Kieu, K.; Norwood, R. A.; Peyghambarian, N.; Luo, J.; Jen, A. K.-Y.

    2014-04-21

    We imaged coplanar poled electro optic (EO) polymer films on transparent substrates with a multiple-photon microscope in reflection and correlated the second-harmonic light intensity with the results of Pockels coefficient (r{sub 33}) measurements. This allowed us to make quantitative measurements of poled polymer films on non-transparent substrates like silicon, which are not accessible with traditional Pockels coefficient measurement techniques. Phase modulators consisting of silicon waveguide devices with EO polymer claddings with a known Pockels coefficient (from V{sub π} measurements) were used to validate the correlation between the second-harmonic signal and r{sub 33}. This also allowed us to locally map the r{sub 33} coefficient in the poled area.

  20. DSC characterization of ion beam modifications in ion conducting PEO salt polymers

    NASA Astrophysics Data System (ADS)

    Maitra, Minakshi; Verma, K. C.; Sinha, Mrinal; Kumar, Rajesh; Middya, T. R.; Tarafdar, S.; Sen, P.; Bandyopadhyay, S. K.; De, Udayan

    2006-03-01

    Ion conducting polymer films have been prepared by complexing non-conducting poly-(ethylene-oxide), PEO, with x fraction of NH4ClO4 salt. Since its electrical conductivity showed a maximum at x somewhere between 0.18 and 0.19, such polymer films having 17 and 19 wt% salt, have been chosen and irradiated by 160 MeV Ne6+ beam. The films have been investigated by differential scanning calorimetry (DSC) and ac impedance spectroscopy before and after the irradiations. Irradiation-induced shift of an endotherm in our DSC indicates a rise in the melting temperature from 54.6 °C to 57.9 °C for the 19% film. Cross-linking by the Ne-irradiation making the polymer structure more rigid can explain this as well as our other observation of a decrease in electrical conductivity.

  1. Characterizing the function of unstructured proteins: Simulations of charged polymers under confinement

    NASA Astrophysics Data System (ADS)

    Bright, Joanne N.; Stevens, Mark. J.; Hoh, Jan; Woolf, Thomas B.

    2001-09-01

    Experimental findings that some polypeptides may be unstructured and behave as entropically driven polymeric spacers in biological systems motivates a study of confined polymers. Here we examine the confinement of neutral, polyampholyte, and polyelectrolyte polymers between two parallel surfaces using course grained models and molecular dynamics. Forces between the confining surfaces are determined for different polymer classes and as a function of chain length, charge sequence (pattern) and degree of confinement. Changes in chain properties are also evaluated under these conditions. The results reinforce the significance of length and net charge for predicting chain properties. In addition the clustering of charge along the chain appears to be critical, and changes in cluster size and distribution produce dramatic changes in chain behavior.

  2. Fabrication and characterization of polymer microfluidic devices for bio-agent detection

    NASA Astrophysics Data System (ADS)

    Morales, Alfredo M.; Brazzle, John D.; Crocker, Robert W.; Domeier, Linda A.; Goods, Eric B.; Hachman, John T., Jr.; Harnett, Cindy K.; Hunter, Marion C.; Mani, Seethambal S.; Mosier, Bruce P.; Simmons, Blake A.

    2004-12-01

    Sandia and Lawrence Livermore National Laboratories are developing a briefcase-sized, broad-spectrum bioagent detection system. This autonomous instrument, the BioBriefcase, will monitor the environment and warn against bacterium, virus, and toxin based biological attacks. At the heart of this device, inexpensive polymer microfluidic chips will carry out sample preparation and analysis. Fabrication of polymer microfluidic chips involves the creation of a master in etched glass; plating of the master to produce a nickel stamp; large lot chip replication by injection molding; and thermal chip sealing. Since the performance and reliability of microfluidic chips are very sensitive to fluidic impedance and to electromagnetic fluxes, the microchannel dimensions and shape have to be tightly controlled during chip fabrication. In this talk, we will present an overview of chip design and fabrication. Metrology data collected at different fabrication steps and the dimensional deviations of the polymer chip from the original design will be discussed.

  3. Fabrication and characterization of polymer microfluidic devices for bio-agent detection

    NASA Astrophysics Data System (ADS)

    Morales, Alfredo M.; Brazzle, John D.; Crocker, Robert W.; Domeier, Linda A.; Goods, Eric B.; Hachman, John T., Jr.; Harnett, Cindy K.; Hunter, Marion C.; Mani, Seethambal S.; Mosier, Bruce P.; Simmons, Blake A.

    2005-01-01

    Sandia and Lawrence Livermore National Laboratories are developing a briefcase-sized, broad-spectrum bioagent detection system. This autonomous instrument, the BioBriefcase, will monitor the environment and warn against bacterium, virus, and toxin based biological attacks. At the heart of this device, inexpensive polymer microfluidic chips will carry out sample preparation and analysis. Fabrication of polymer microfluidic chips involves the creation of a master in etched glass; plating of the master to produce a nickel stamp; large lot chip replication by injection molding; and thermal chip sealing. Since the performance and reliability of microfluidic chips are very sensitive to fluidic impedance and to electromagnetic fluxes, the microchannel dimensions and shape have to be tightly controlled during chip fabrication. In this talk, we will present an overview of chip design and fabrication. Metrology data collected at different fabrication steps and the dimensional deviations of the polymer chip from the original design will be discussed.

  4. Characterization of HPMC/PVP polymer blend films using WAXS technique

    NASA Astrophysics Data System (ADS)

    Prakash, Y.; Somashekarappa, H.; Parameswara, P.; Demappa, T.; Somashekar, R.

    2012-06-01

    Hydroxy propyl methyl cellulose (HPMC) and Poly vinyl pyrrolidone (PVP) polymer blend films were prepared and investigated using X-ray line profile analysis method. Here an attempt has been made to study the changes in the crystallite size and lattice strain in HPMC with the increase in concentration of PVP. Decrease in these microcrystalline parameters implies increase in the amorphous nature of the film giving more flexibility, degradability and good miscibility. Micro structural parameters reveals that the blend films have more amorphous nature than virgin HPMC. This further justified by SEM images which indicate better miscibility of the two polymers in the blend matrix.

  5. Modification and characterization of fluorescent conjugated polymer nanoparticles for single molecule detection

    NASA Astrophysics Data System (ADS)

    Zheng, Yueli

    Single molecule tracking using fluorescent dye or nanoparticle labels has emerged as a useful technique for probing biomolecular processes. Considerable interest arises in the development of nanoparticle labels with brighter fluorescence in order to improve the spatial and temporal resolution of single molecule detection and to facilitate the application of single molecule detection methods to a wider range of intracellular processes. The McNeill laboratory recently reported that conjugated polymer nanoparticles exhibit fluorescence cross-sections roughly 10--100 times higher than other luminescent nanoparticles of similar size, excellent photostability (2.2x108 photons emitted per nanoparticle prior to photobleaching), and saturated emission rates roughly 100 times higher than that of the molecular dyes and more than 1000 times higher than that of colloidal semiconductor quantum dots. One purpose of this graduate research is the development of highly fluorescent, bioconjugated nanoparticle labels based on conjugated polymers for demanding fluorescence applications such as single molecule tracking in live cells. Three surface modification methods (conjugated polymer nanoparticles encapsulated with lipid silica agents, conjugated polymer nanoparticles encapsulated with tetraethyl orthosilicate(TEOS) and hybrid nanoparticles with thiol pendant groups by the Stober Method (3-mercaptopropyl trimethoxysilane (MPS))) have been developed to protect the conjugated polymer, passivate the nanoparticle surface, and provide a chemical handle for bioconjugation such as nanoparticle encapsulation with alkoxysilanes and Stober method. After encapsulation, the fluorescence quantum yield of silica-encapsulated nanoparticles is improved by 20% as compared to bare conjugated polymer nanoparticles, while the photostability is improved by a factor of 2, indicating that some protection of the polymer is provided by the encapsulating layer. Another purpose of my research is the

  6. ALKALINE-SURFACTANT-POLYMER FLOODING AND RESERVOIR CHARACTERIZATION OF THE BRIDGEPORT AND CYPRESS RESERVOIRS OF THE LAWRENCE FIELD

    SciTech Connect

    Malcolm Pitts; Ron Damm; Bev Seyler

    2003-03-01

    Feasibility of alkaline-surfactant-polymer flood for the Lawrence Field in Lawrence County, Illinois is being studied. Two injected formulations are being designed; one for the Bridgeport A and Bridgeport B reservoirs and one for Cypress and Paint Creek reservoirs. Fluid-fluid and coreflood evaluations have developed a chemical solution that produces incremental oil in the laboratory from the Cypress and Paint Creek reservoirs. A chemical formulation for the Bridgeport A and Bridgeport B reservoirs is being developed. A reservoir characterization study is being done on the Bridgeport A, B, & D sandstones, and on the Cypress sandstone. The study covers the pilot flood area and the Lawrence Field.

  7. ALKALINE-SURFACTANT-POLYMER FLOODING AND RESERVOIR CHARACTERIZATION OF THE BRIDGEPORT AND CYPRESS RESERVOIRS OF THE LAWRENCE FIELD

    SciTech Connect

    Malcolm Pitts; Ron Damm; Bev Seyler

    2003-04-01

    Feasibility of alkaline-surfactant-polymer flood for the Lawrence Field in Lawrence County, Illinois is being studied. Two injected formulations are being designed; one for the Bridgeport A and Bridgeport B reservoirs and one for Cypress and Paint Creek reservoirs. Fluid-fluid and coreflood evaluations have developed a chemical solution that produces incremental oil in the laboratory from the Cypress and Paint Creek reservoirs. A chemical formulation for the Bridgeport A and Bridgeport B reservoirs is being developed. A reservoir characterization study is being done on the Bridgeport A, B, & D sandstones, and on the Cypress sandstone. The study covers the pilot flood area and the Lawrence Field.

  8. Preparation and characterization of polymer layer systems for validation of 3D Micro X-ray fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Schaumann, Ina; Malzer, Wolfgang; Mantouvalou, Ioanna; Lühl, Lars; Kanngießer, Birgit; Dargel, Rainer; Giese, Ulrich; Vogt, Carla

    2009-04-01

    For the validation of the quantification of the newly-developed method of 3D Micro X-ray fluorescence spectroscopy (3D Micro-XRF) samples with a low average Z matrix and minor high Z elements are best suited. In a light matrix the interferences by matrix effects are minimized so that organic polymers are appropriate as basis for analytes which are more easily detected by X-ray fluorescence spectroscopy. Polymer layer systems were assembled from single layers of ethylene-propylene-diene rubber (EPDM) filled with changing concentrations of silica and zinc oxide as inorganic additives. Layer thicknesses were in the range of 30-150 μm. Before the analysis with 3D Micro-XRF all layers have been characterized by scanning micro-XRF with regard to filler dispersion, by infrared microscopy and light microscopy in order to determine the layer thicknesses and by ICP-OES to verify the concentration of the X-ray sensitive elements in the layers. With the results obtained for stacked polymer systems the validity of the analytical quantification model for the determination of stratified materials by 3D Micro-XRF could be demonstrated.

  9. Synthesis and characterization of an insoluble polymer based on polyamidoamine: applications for the decontamination of metals in aqueous systems.

    PubMed

    Valdés, Oscar; Vergara, Claudia E; Camarada, Maria B; Carrasco-Sánchez, Veronica; Nachtigall, Fabiane M; Tapia, Jaime; Fischer, Rainer; González-Nilo, F D; Santos, Leonardo S

    2015-01-01

    We present a novel, insoluble, low-generation polyamidoamine (PAMAM)-based polymer. The monomer and polymer were characterized by fourier transform infrared spectroscopy, electrospray ionization mass spectrometry and thermogravimetric measurement, revealing that G0 acryloyl-terminated PAMAM were synthesized and polymerized using ammonium persulfate as an initiator, producing a high-density PAMAM derivative (PAMAM-HD). PAMAM-HD was tested for its ability to remove Na(I), K(I), Ca(II), Mg(II), Cu(II), Mn(II), Cd(II), Pb(II) and Zn(II) ions from acidic, neutral and basic aqueous solutions. PAMAM-HD efficiently removed metals ions from all three solutions. The greatest absorption efficiency at neutral pH was observed against Cu(II), Cd(II) and Pb(II), and the experimental data were supported by the calculated Kd values. Our data could have a significant impact on water purification by providing an inexpensive and efficient polymer for the removal of metal ions.

  10. Polymer gel dosimetry for the TG-43 dosimetric characterization of a new 125I interstitial brachytherapy seed.

    PubMed

    Papagiannis, P; Pantelis, E; Georgiou, E; Karaiskos, P; Angelopoulos, A; Sakelliou, L; Stiliaris, S; Baltas, D; Seimenis, I

    2006-04-21

    In this work, a polymer gel-magnetic resonance (MR) imaging method is employed for the dosimetric characterization of a new 125I low dose rate seed (IsoSeed model I25.S17). Two vials filled with PABIG gel were prepared in-house and one new seed as well as one commercially available 125I seed of similar dose rate and well-known dosimetric parameters (IsoSeed model I25.S06) were positioned in each vial. Both seeds in each vial were MR scanned simultaneously on days 11 and 26 after implantation. The data obtained from the known seed in each vial are used to calibrate the gel dose response which, for the prolonged irradiation duration necessitated by the investigated dose rates, depends on the overall irradiation time. Data for this study are presented according to the AAPM TG-43 dosimetric formalism. Polymer gel results concerning the new seed are compared to corresponding, published dosimetric results obtained, for the purpose of the new seed clinical implementation, by our group using the established methods of Monte Carlo (MC) simulation and thermo-luminescence dosimetry (TLD). Polymer gel dosimetry yields an average dose rate constant value of lambda = (0.921 +/- 0.031) cGy h(-1) U(-1) relative to (MC)lambda = (0.929 +/- 0.014) cGy h(-1) U(-1), (TLD)lambda = (0.951 +/- 0.044) cGy h(-1) U(-1) and the average value of Lambda = (0.940 +/- 0.051) cGy h(-1) U(-1) proposed for the clinical implementation of the new seed. Results for radial dose function, g(L)(r), and anisotropy function, F(r, theta), also agree with corresponding MC calculations within experimental uncertainties which are smaller for the polymer gel method compared to TLD. It is concluded that the proposed polymer gel-magnetic resonance imaging methodology could be used at least as a supplement to the established techniques for the dosimetric characterization of new low energy and low dose rate interstitial brachytherapy seeds.

  11. The synthesis and characterization of environmentally-responsive water-swellable and water-soluble polymers for wastewater remediation

    NASA Astrophysics Data System (ADS)

    Armentrout, Rodney Scott

    The primary research goal is the development of new polymeric materials that demonstrate the environmentally-responsive sequestration of common water foulants, including surfactants and oils. Water-swellable and water-soluble polymers have been synthesized, structurally characterized, and their physical properties have been determined. In addition, the ability of the materials to sequester model water foulants has been evaluated. Anionic crosslinked polymer networks of 2-acrylamido-2-methyl-1-propanesulfonic acid, acrylamide, and methylene bisacrylamide have been synthesized and characterized by determining the equilibrium water contents as a function of ionic content of the polymer network. The molar ratio of bound surfactant to ionic group was determined to be less than one for all hydrogels studied, indicating an ion-exchange binding mechanism with minimal hydrophobic interactions between bound and unbound surfactant molecules is responsible for surfactant binding. Cationic crosslinked cyclopolymer networks of N,N-diallyl- N-methyl amine (DAMA) and N,N,N,N-tetraallyl ammonium chloride (TAAC) have been synthesized and characterized by determining the equilibrium water content as a function of pH. A maximum in the equilibrium water content is observed for pH-6 when the polymer is fully ionized. The solubilization of a model water foulant, p-cresol, by the polymeric surfactant, Pluronic F127, has been studied via equilibrium dialysis, dynamic light scattering and ultrafiltration experiments. It has been shown that at 25°C p-cresol is readily solubilized by F127 since the polymeric surfactant exists in a multimer conformation. Ultrafiltration experiments have demonstrated that the polymer-foulant binding interactions are largely unaffected by shear in a hollow fiber membrane. Copolymers of the zwitterionic monomer, 3-(N,N-diallyl- N-methyl ammonio) propane sulfonate (DAMAPS) and N,N-diallyl- N,N-dimethylammonium chloride (DADMAC) (the DADS series) or the p

  12. Processing and electrical characterization in intrinsic conducting polymers for electronic and MEMS applications

    NASA Astrophysics Data System (ADS)

    Seifert, Wilhelm; Albrecht, Henrik; Mietke, Stephan; Koehler, Thomas; Werner, Matthias

    2003-07-01

    Electronic polymer devices and test structures based on PEDOT/PSS were fabricated in a fully CMOS compatible process. The resistivity of PEDOT/PSS polymer films is dependent on film thickness. The resistivity increases with decreasing film thickness for polymer film thicknesses between 190 nm and 380 nm. The resistivity differs by a factor of ~3 depending on film thickness. The evaluation of the specific contact resistivity depending on the choice of the metallization leads to a difference of the specific contact resistivity by a factor of 190. The specific contact resistivity does not follow the Schottky-Mott law and thus indicates a non-ideal behavior of the metal PEDOT/PSS interface. The lowest average specific contact resistivity was obtained for silver with an average value of 0.14 Ωcm2 and the highest specific contact resistivity was obtained for platinum. Even the lowest specific contact resistivity for silver is still very high when compared with low resistivity ohmic contacts to silicon. However, the specific contact resistivity is expected to have a significant drawback for overall device performance. Possible future applications of MEMS and electronics based on polymers will be for simple devices like transistors, ID tags, thermistors, acceleration and pressure sensors as well as radiation and UV detectors.

  13. Development and Characterization of Poly(1-vinylpyrrolidone-co-vinyl acetate) Copolymer Based Polymer Electrolytes

    PubMed Central

    Sa'adun, Nurul Nadiah; Subramaniam, Ramesh; Kasi, Ramesh

    2014-01-01

    Gel polymer electrolytes (GPEs) are developed using poly(1-vinylpyrrolidone-co-vinyl acetate) [P(VP-co-VAc)] as the host polymer, lithium bis(trifluoromethane) sulfonimide [LiTFSI] as the lithium salt and ionic liquid, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [EMImTFSI] by using solution casting technique. The effect of ionic liquid on ionic conductivity is studied and the optimum ionic conductivity at room temperature is found to be 2.14 × 10−6 S cm−1 for sample containing 25 wt% of EMImTFSI. The temperature dependence of ionic conductivity from 303 K to 353 K exhibits Arrhenius plot behaviour. The thermal stability of the polymer electrolyte system is studied by using thermogravimetric analysis (TGA) while the structural and morphological properties of the polymer electrolyte is studied by using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction analysis (XRD), respectively. PMID:25431781

  14. Synthesis, characterization, and ab initio theoretical study of a molecularly imprinted polymer selective for biosensor materials.

    PubMed

    Jacob, Rebecca; Tate, Margaret; Banti, Yididya; Rix, Colin; Mainwaring, David E

    2008-01-17

    Despite the complex phenomena involved in encoding template molecule information within stable synthetic polymers to yield selective and efficient molecular recognition processes, molecularly imprinted polymers (MIP) are increasingly finding broad areas of application. Molecular interactions, both during the polymerization of the functional monomers in the presence of the template and during the processes of specific recognition after template removal, are key determinants of an effective MIP. Covalent and noncovalent template imprinting have been employed to achieve specific recognition sites. In the present study, a molecularly imprinted biocompatible polymer, having a high capacity and affinity for the dye template, nickel(II) phthalocyanine tetrasulfonic acid, has been prepared. UV-visible spectroscopy, FTIR spectroscopy, and ICP analysis were used to investigate the aspects of the synthesis, binding capacity, and adsorption kinetics of the system. Poly(allylamine) cross-linked with epichlorohydrin has been used to represent an amino-functional receptor. Binding isotherms and capacities were correlated with the degree of template removal. Kinetic studies of binding allowed diffusion mechanisms to be evaluated for the fine particulate MIP. Ab initio molecular orbital calculations were performed using Hartree-Fock, MP2, and density functional theory methods to determine the most likely mechanisms of molecular imprinting. Suitable theoretical models have been constructed to mimic the interactions between the template molecule and the polymer. Simulation of the vibrational spectra was also undertaken to make meaningful assignments to experimentally determined spectral bands resulting from these template MIP receptor interactions.

  15. A thermosensitive carrageenan-based polymer: synthesis, characterization and interactions with a cationic surfactant.

    PubMed

    Gaweł, Kamila; Karewicz, Anna; Bielska, Dorota; Szczubiałka, Krzysztof; Rysak, Katarzyna; Bonarek, Piotr; Nowakowska, Maria

    2013-07-01

    Novel polyelectrolytes were obtained by grafting N-isopropylacrylamide (NIPAM) on the ι-carrageenan (CAR) chain. Two polymers with different grafting degrees were synthesized. The polymers were found to show the lower critical solution temperature (LCST) close to that of PNIPAM. The LCST values were dependent on the concentration of salt and cationic surfactant. The interactions of CAR-graft-PNIPAM with a model cationic surfactant-dodecyltrimethyl ammonium chloride (DTAC) in water and 0.15M NaCl were studied. It was found that both ι-carrageenan and CAR-graft-PNIPAM polymers interact with DTAC. The presence of CAR-graft-PNIPAM in the solution of DTAC induces formation of surfactant aggregates at the critical aggregation concentration much lower than the cmc of the surfactant. Cac increased with ionic strength. The values of cac for CAR-graft-PNIPAM - DTAC system and standard free enthalpy changes attributed to the complexation process were determined. The results obtained for CAR-graft-PNIPAM were compared with these for the non-modified ι-carrageenan. The surfactant interactions with non-modified and grafted polymers were found to be different in nature.

  16. Structural and optical characterization of PVA:KMnO4 based solid polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Abdullah, Omed Gh.; Aziz, Shujahadeen B.; Rasheed, Mariwan A.

    Solid polymer electrolyte films of polyvinyl alcohol (PVA) doped with a different weight percent of potassium permanganate (KMnO4) were prepared by standard solution cast method. XRD and FTIR techniques were performed for structural study. Complex formation between the PVA polymer and KMnO4 salt was confirmed by Fourier transform infrared (FTIR) spectroscopy. The description of crystalline nature of the solid polymer electrolyte films has been confirmed by XRD analysis. The UV-Visible absorption spectra were analyzed in terms of absorption formula for non-crystalline materials. The fundamental optical parameters such as optical band gap energy, refractive index, optical conductivity, and dielectric constants have been investigated and showed a clear dependence on the KMnO4 concentration. The observed value of optical band gap energy for pure PVA is about 6.27 eV and decreases to a value 3.12 eV for the film sample formed with 4 wt% KMnO4 salt. The calculated values of refractive index and the dielectric constants of the polymer electrolyte films increase with increasing KMnO4 content.

  17. HCN polymers characterized by SSNMR: Solid state reaction of crystalline tetramer (diaminomaleonitrile)

    NASA Astrophysics Data System (ADS)

    Mamajanov, Irena; Herzfeld, Judith

    2009-04-01

    The HCN tetramer, diaminomaleonitrile, crystallizes in sheets with amine and nitrile groups of neighboring molecules in close proximity. This suggests the possibility of relatively facile acid-base addition to form a protopeptide polymer. We find that moderate heating under argon indeed results in an unmistakable reaction, with the abrupt transformation of pale crystallites to shrunken dark particles that become electrically conductive upon doping with iodine. Since nearly a quarter of the mass is lost in the process and the released gas condenses, polymerizes, and reacts with aqueous AgNO3 like HCN, it seems likely that the dark solid is a polymer of HCN trimer. C13 and N15 solid state NMR spectra show the formation of new N-C bonds, and entirely different functional groups from those observed in polymers formed by liquid HCN. These include three different types of nitrogen functionalities and an absence of saturated carbon or nitrile. The observed chemical shifts, optical properties, and electrical conductivity are consistent with polymers of HCN trimer that have undergone cyclization to form poly-[aminoimidazole].

  18. Characterization of Polyaniline Based Polymer Light-Emitting Devices During Operation by Electrical Impedance Spectroscopy

    DTIC Science & Technology

    2004-07-01

    regions. 2. Experimental The light-emitting devices were prepared by Covion by spin coating and curing a 80 nm layer of Pani/PSS as HIL onto indium...tin oxide (ITO) patterned glass substrates followed by spin coating of the 80 nm light-emitting polymer layer. A water based Pani/PSS dispersion

  19. The modulation of physicochemical characterization of innovative liposomal platforms: the role of the grafted thermoresponsive polymers.

    PubMed

    Chountoulesi, Maria; Kyrili, Aimilia; Pippa, Natassa; Meristoudi, Anastasia; Pispas, Stergios; Demetzos, Costas

    2017-05-01

    This study is focused on chimeric advanced drug delivery systems and specifically on thermosensitive liposomes, combining lipids and thermoresponsive polymers. In this investigation, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) chimeric liposomal systems were prepared, incorporating the homopolymer C12H25-poly(N-isopropylacrylamide)-COOH (C12H25-PNIPAM-COOH) and the block copolymer poly(n-butylacrylate-b-N-isoropylacrylamide) (PnBA-PNIPAM), at six different molar ratios. Both of these polymers contain the thermoresponsive PNIPAM block, which exhibits lower critical solution temperature (LCST) at 32 °C in aqueous solutions, changing its nature from hydrophilic to hydrophobic above LCST. During the preparation of liposomes, the dispersions were observed visually, while after the preparation we studied the alterations of the physicochemical characteristics, by measuring the size, size distribution and ζ-potential of prepared liposomes. The presence of polymer, either C12H25-PNIPAM-COOH or PnBA-PNIPAM, resulted in liposomes exhibiting different physicochemical characteristics in comparison to conventional DPPC liposomes. At the highest percentage of the polymeric guest, chimeric liposomes were found to retain their size during the stability studies. The incorporation of the appropriate amount of these novel thermoresponsive polymers yields liposomal stabilization and imparts thermoresponsiveness, due to the functional PNIPAM block.

  20. Synthesis and structural characterization of a single-crystal to single-crystal transformable coordination polymer.

    PubMed

    Tian, Yuyang; Allan, Phoebe K; Renouf, Catherine L; He, Xiang; McCormick, Laura J; Morris, Russell E

    2014-01-28

    A single-crystal to single-crystal transformable coordination polymer compound was hydrothermally synthesized. The structural rearrangement is induced by selecting a ligand that contains both strong and weaker coordinating groups. Both hydrated and dehydrated structures were determined by single crystal X-ray analysis.

  1. Dosimetric characterization of CyberKnife radiosurgical photon beams using polymer gels

    SciTech Connect

    Pantelis, E.; Antypas, C.; Petrokokkinos, L.; Karaiskos, P.; Papagiannis, P.; Kozicki, M.; Georgiou, E.; Sakelliou, L.; Seimenis, I.

    2008-06-15

    Dose distributions registered in water equivalent, polymer gel dosimeters were used to measure the output factors and off-axis profiles of the radiosurgical photon beams employed for CyberKnife radiosurgery. Corresponding measurements were also performed using a shielded silicon diode commonly employed for CyberKnife commissioning, the PinPoint ion chamber, and Gafchromic EBT films, for reasons of comparison. Polymer gel results of this work for the output factors of the 5, 7.5, and 10 mm diameter beams are (0.702{+-}0.029), (0.872{+-}0.039), and (0.929{+-}0.041), respectively. Comparison of polymer gel and diode measurements shows that the latter overestimate output factors of the two small beams (5% for the 5 mm beam and 3% for the 7.5 mm beams). This is attributed to the nonwater equivalence of the high atomic number silicon material of the diode detector. On the other hand, the PinPoint chamber is found to underestimate output factors up to 10% for the 5 mm beam due to volume averaging effects. Polymer gel and EBT film output factor results are found in close agreement for all beam sizes, emphasizing the importance of water equivalence and fine detector sensitive volume for small field dosimetry. Relative off-axis profile results are in good agreement for all dosimeters used in this work, with noticeable differences observed only in the PinPoint estimate of the 80%-20% penumbra width, which is relatively overestimated.

  2. Synthesis, characterization, and transistor response of semiconducting silole polymers with substantial hole mobility and air stability. Experiment and theory.

    PubMed

    Lu, Gang; Usta, Hakan; Risko, Chad; Wang, Lian; Facchetti, Antonio; Ratner, Mark A; Marks, Tobin J

    2008-06-18

    Realizing p-channel semiconducting polymers with good hole mobility, solution processibility, and air stability is an important step forward in the chemical manipulation of charge transport in polymeric solids and in the development of low-cost printed electronics. We report here the synthesis and full characterization of the dithienosilole- and dibenzosilole-based homopolymers, poly(4,4-di-n-hexyldithienosilole) (TS6) and poly(9,9-di-n-octyldibenzosilole) (BS8), and their mono- and bithiophene copolymers, poly(4,4-di-n-hexyldithienosilole-alt-(bi)thiophene) (TS6T1, TS6T2) and poly(9,9-di-n-octyldibenzosilole-alt-(bi)thiophene) (BS8T1, BS8T2), and examine in detail the consequences of introducing dithienosilole and dibenzosilole cores into a thiophene polymer backbone. We demonstrate air-stable thin-film transistors (TFTs) fabricated under ambient conditions having hole mobilities as large as 0.08 cm(2)/V x s, low turn-on voltages, and current on/off ratios > 10(6). Additionally, unencapsulated TFTs fabricated under ambient conditions are air-stable, an important advance over regioregular poly(3-hexylthiophene) (P3HT)-based devices. Density functional theory calculations provide detailed insight into the polymer physicochemical and charge transport characteristics. A direct correlation between the hole injection barrier and both TFT turn-on voltage and TFT polymer hole mobility is identified and discussed, in combination with thin-film morphological characteristics, to explain the observed OTFT performance trends.

  3. Molecular Dynamics Simulations of Spinodal-Assisted Polymer Crystallization

    SciTech Connect

    Gee, R H; Lacevic, N M; Fried, L

    2005-07-08

    Large scale molecular dynamics simulations of bulk melts of polar (poly(vinylidene fluoride) (pVDF)) polymers are utilized to study chain conformation and ordering prior to crystallization under cooling. While the late stages of polymer crystallization have been studied in great detail, recent theoretical and experimental evidence indicates that there are important phenomena occurring in the early stages of polymer crystallization that are not understood to the same degree. When the polymer melt is quenched from a temperature above the melting temperature to the crystallization temperature, crystallization does not occur instantaneously. This initial interval without crystalline order is characterized as an induction period. It has been thought of as a nucleation period in the classical theories of polymer crystallization, but recent experiments, computer simulations, and theoretical work suggest that the initial period in polymer crystallization is assisted by a spinodal decomposition type mechanism. In this study we have achieved physically realistic length scales to study early stages of polymer ordering, and show that spinodal-assisted ordering prior to crystallization is operative in polar polymers suggesting general applicability of this process.

  4. Synthesis and characterization of high molecular weight water-soluble polymers to study the role of extensional viscosity in polymeric drag reduction

    NASA Astrophysics Data System (ADS)

    Cowan, Martin E.

    Several high molecular weight water-soluble acrylamide copolymers identified as efficient drag reducers have been synthesized, characterized, and examined for drag reduction effectiveness. Commercially supplied poly(ethylene oxide) polymers of varying molecular weight were also characterized and studied for comparison. The resistance to polymer extension was measured using a screen extensional rheometer allowing for the local extensional viscosity of each polymer to be quantified. Copolymer composition was determined using 13C NMR. Dilute solution properties and molecular weights were determined from zero shear intrinsic viscosity measurements and multi-angle laser light scattering experiments respectively. Molecular weights ranged from 0.55 to 4.3 million grams per mole. Drag reduction measurements were performed using a rotating disk instrument. Drag reduction data were analyzed by several theoretical models. The best correlation was found using the energy model of Walsh. Empirically, drag reduction was found to be directly related to the local extensional viscosity of each polymer sample. A model is presented explaining drag reduction in terms of increased local viscosity leading to decreased turbulence characterized with a decreased local Reynolds number. Molecular weight was found to be the most important molecular parameter of the polymers studied with polymers of greater molecular weight showing superior drag reduction properties.

  5. Spectral and spatial characterization of perfluorinated graded-index polymer optical fibers for the distribution of optical wireless communication cells.

    PubMed

    Hajjar, Hani Al; Montero, David S; Lallana, Pedro C; Vázquez, Carmen; Fracasso, Bruno

    2015-02-10

    In this paper, the characterization of a perfluorinated graded-index polymer optical fiber (PF-GIPOF) for a high-bitrate indoor optical wireless system is reported. PF-GIPOF is used here to interconnect different optical wireless access points that distribute optical free-space high-bitrate wireless communication cells. The PF-GIPOF channel is first studied in terms of transmission attenuation and frequency response and, in a second step, the spatial power profile distribution at the fiber output is analyzed. Both characterizations are performed under varying restricted mode launch conditions, enabling us to assess the transmission channel performance subject to potential connectorization errors within an environment where the end users may intervene by themselves on the home network infrastructure.

  6. Surface characterization of polymer-drug modified vascular stents and intraocular lenses

    NASA Astrophysics Data System (ADS)

    Elachchabi, Amin

    human coronary smooth muscle cell growth in vitro whereas dexamethasone exhibited no similar effect. A second major subject of this research was a series of studies concerning the properties of foldable hydrophobic acrylic intraocular lenses (IOLs) which have not previously been investigated. Most IOLs implanted today in the U.S. and the western world are foldable. The goal of this research was to conduct new surface characterization studies on the surfaces of several different foldable lenses in clinical use. Atomic force microscopy showed that these IOLs have different morphologies and that hydration greatly altered the surface morphology of these implants. Contact angle goniometry studies indicated that water contact angles varied significantly from one lens to the other and that prolonged hydration led to a reduction of the water contact angle. Nanoindentation experiments yielded new information on the surface mechanical properties of IOLs and a new methodology was developed to analyze nanoindent data to determine the surface modulus and hardness of foldable IOLs and low modulus polymers in general. The novel surface properties studies reported here can be important in guiding the design and the development of new ocular implants.

  7. New way to characterize the percolation threshold of polyethylene and carbon nanotube polymer composites using Fourier transform (FT) rheology

    NASA Astrophysics Data System (ADS)

    Ahirwal, Deepak; Palza, Humberto; Schlatter, Guy; Wilhelm, Manfred

    2014-08-01

    In this article, a new way to characterize the percolation threshold of polymer nanocomposites made of polyethylene (PE) with single and multi walled carbon nanotubes (SWCNTs and MWCNTs) is presented. Small and large oscillatory shear (SAOS and LAOS) experiments were performed to characterize the degree of dispersion and percolation threshold. The analysis of the stress response in the LAOS regime as a function of the applied deformation amplitude and frequency was performed using Fourier Transform (FT)-Rheology. The zero strain intrinsic nonlinear parameter, Q0(ω), was calculated by extrapolation of I3/1(γ0, ω) and was, used to quantify the nonlinearity measured by FT-Rheology. Interestingly, a drop in Q0 as a function of the CNT weight fraction at a fixed frequency was found that was below the percolation threshold. This was followed by, a steep rise in Q0 above the percolation threshold. Therefore, the new method based on this observation that is proposed and described with this article has the potential to lead to a better understanding of structure-property relationships in polymer nanocomposites.

  8. Physicochemical characterization and toxicological evaluation of plant-based anionic polymers and their nanoparticulated system for ocular delivery.

    PubMed

    Pathak, Deepa; Kumar, Prashant; Kuppusamy, Gowthamarajan; Gupta, Ankur; Kamble, Bhagyashree; Wadhwani, Ashish

    2014-12-01

    The water-soluble fractions of mucilages and gum from the seeds of fenugreek, isphagula and mango bark exudate were isolated, purified and characterized using X-ray diffraction (XRD) spectrometry, Fourier transform infrared spectroscopy (FT-IR), maldi/GC-MS, elemental analysis, 1D ((1)H and (13)C) and 2D (HMQC, COSY) nuclear magnetic resonance spectroscopy (NMR). The fenugreek mucilage was identified to be a galactomannan chain consisting of 4 units of galactose attached to the backbone of 6 mannose units in 1:1.5 ratio. The isphagula mucilage was identified to be an arabinoxylan polysaccharide chain consisting of 4 units of arabinofuranose attached to the backbone of 9 xylopyrannose units in 1:3 ratio. The mango gum showed the presence of amylose, α-arabinofuranosyl and β-galactopyranosyl, respectively. The characterized mucilages and gum were individually formulated into nanoparticulate system using their complementarily charged polymer chitosan. The particles were observed to be spherical in shape in the range of 61.5-90 nm having zetapotential between 31 and 34 mV and PDI of 0.097-0.241. The prepared nanoparticles were observed to be nonirritant and nontoxic in vitro and in vivo upto 2000 μg/ml. Therefore, these mucilages and gum can be the alternatives of anionic polymers for the ocular drug delivery system.

  9. Fabrication and Characterization of a Micromachined Swirl-Shaped Ionic Polymer Metal Composite Actuator with Electrodes Exhibiting Asymmetric Resistance

    PubMed Central

    Feng, Guo-Hua; Liu, Kim-Min

    2014-01-01

    This paper presents a swirl-shaped microfeatured ionic polymer-metal composite (IPMC) actuator. A novel micromachining process was developed to fabricate an array of IPMC actuators on a glass substrate and to ensure that no shortcircuits occur between the electrodes of the actuator. We demonstrated a microfluidic scheme in which surface tension was used to construct swirl-shaped planar IPMC devices of microfeature size and investigated the flow velocity of Nafion solutions, which formed the backbone polymer of the actuator, within the microchannel. The unique fabrication process yielded top and bottom electrodes that exhibited asymmetric surface resistance. A tool for measuring surface resistance was developed and used to characterize the resistances of the electrodes for the fabricated IPMC device. The actuator, which featured asymmetric electrode resistance, caused a nonzero-bias current when the device was driven using a zero-bias square wave, and we propose a circuit model to describe this phenomenon. Moreover, we discovered and characterized a bending and rotating motion when the IPMC actuator was driven using a square wave. We observed a strain rate of 14.6% and a displacement of 700 μm in the direction perpendicular to the electrode surfaces during 4.5-V actuation. PMID:24824370

  10. Fabrication and characterization of a micromachined swirl-shaped ionic polymer metal composite actuator with electrodes exhibiting asymmetric resistance.

    PubMed

    Feng, Guo-Hua; Liu, Kim-Min

    2014-05-12

    This paper presents a swirl-shaped microfeatured ionic polymer-metal composite (IPMC) actuator. A novel micromachining process was developed to fabricate an array of IPMC actuators on a glass substrate and to ensure that no shortcircuits occur between the electrodes of the actuator. We demonstrated a microfluidic scheme in which surface tension was used to construct swirl-shaped planar IPMC devices of microfeature size and investigated the flow velocity of Nafion solutions, which formed the backbone polymer of the actuator, within the microchannel. The unique fabrication process yielded top and bottom electrodes that exhibited asymmetric surface resistance. A tool for measuring surface resistance was developed and used to characterize the resistances of the electrodes for the fabricated IPMC device. The actuator, which featured asymmetric electrode resistance, caused a nonzero-bias current when the device was driven using a zero-bias square wave, and we propose a circuit model to describe this phenomenon. Moreover, we discovered and characterized a bending and rotating motion when the IPMC actuator was driven using a square wave. We observed a strain rate of 14.6% and a displacement of 700 μm in the direction perpendicular to the electrode surfaces during 4.5-V actuation.

  11. Methodologies for Controlled Conjugated Polymer Synthesis and Characterization of Small Molecule Organic Semiconductors

    NASA Astrophysics Data System (ADS)

    Bakus, Ronald C., II

    Conjugated polymers can broadly be described as materials which have a structure composed of repeating monomeric units that show extended electronic communication along the backbone. The extended pi-conjugated nature of these materials gives them a set of unique electronic and optical properties, and has lead to their application in a multitude of various technologies. Of specific interest is the application of these materials in various organic electronics applications, such as solution processed plastic solar cells, light emitting diodes, and field effect transistors. Herein is described the synthesis of a class of well-defined, highly active organometallic initiators for use in controlled polymer synthesis. The polymers prepared using the nickel based initiators in Grignard metathesis polymerization posses the following characteristics: rapid generation of high molecular weight polymers, low polydispersity, linear relation between monomer conversion and molecular weight growth, and the selective transfer of an initiating moiety from the organometallic initiator to one polymer chain end. This initiator was then used to prepare a new class of biosensor materials wherein the polymer had a well defined biosensing end group. Additionally, a series of small molecule donors have been developed that have shown promise in a wide variety of organic electronic applications. These materials can broadly be described as having a D'ADAD' type structure where D, D', and A correspond to electron rich and electron deficient aromatic heterocycles, respectively. By tuning the identity of these groups and the side-chains attached to them, one can subtly influence the optical, electronic, and physical properties of the materials. These materials were investigated via single crystal x-ray diffraction studies to gain insight into how changes to the molecule structure such as heteroatom regioisomerism and isoelectronic substitutions effected the molecular structure. These changes in

  12. Growth and characterization of CdS thin films on polymer substrates for photovoltaic applications.

    PubMed

    Park, Yongseob; Kim, Eung Kwon; Lee, Suho; Lee, Jaehyeong

    2014-05-01

    In this work, cadmium sulfide (CdS) films were deposited on flexible polymer substrates such as polycarbonate (PC) and polyethylene terephthalate (PET). The r.f. magnetron sputtering, which is cost-effective scalable technique, was used for the film deposition. The structural and optical properties of the films grown at different sputtering pressures were investigated. When the CdS film was deposited at lower pressure, the crystallinity and the preferred orientation toward c-axis in hexagonal phase was improved. However, the optical transmittance was reduced as the sputtering pressure was decreased. Compared with the glass substrate, CdS films grown on polymer substrates were exhibited some wore structural and optical characteristics. CdTe thin film solar cell applied to sputtered CdS as a window layer showed a maximum efficiency of 11.6%.

  13. Edible oleogels based on water soluble food polymers: preparation, characterization and potential application.

    PubMed

    Patel, Ashok R; Cludts, Nick; Sintang, Mohd Dona Bin; Lesaffer, Ans; Dewettinck, Koen

    2014-11-01

    Oil structuring using food-approved polymers is an emerging strategy and holds significant promise in the area of food and nutrition. In the current study, edible oleogels (containing >97 wt% of sunflower oil) were prepared using a combination of water soluble food polymers (methylcellulose and xanthan gum) and further evaluated for potential application as a shortening alternative. Microstructure studies (including cryo-SEM) and rheology measurements were conducted to gain more insights into the properties of these new types of oleogels. In addition, the functionality of oleogel as a shortening alternative was studied in terms of batter properties and the texture analysis of cakes and compared to the reference batches made using either oil, commercial shortening or cake margarine. Interestingly, while the batter properties (air incorporation, rheology and microstructure) of the oleogel batch were more close to the oil batch, the textural properties of cakes were significantly better than oil and resembled more to the cakes prepared using shortening and margarine.

  14. Characterization of ionic permeability and water vapor transmission rate of polymers used for implantable electronics.

    PubMed

    Kirsten, Sabine; Schubert, Martin; Uhlemann, Jürgen; Wolter, Klaus-Jurgen

    2014-01-01

    Biocompatible polymers used as encapsulation and packaging materials for implantable electronic devices have to comply with numerous requirements. Especially their barrier properties against water molecules and ions are of particular interest regarding the reliability of the encapsulation as well as functional integrity of the electronic components since water and ions on the circuit board may evoke corrosion, leakage current and finally the failure of the device. This paper describes a measurement setup to investigate the ionic permeability under in vitro conditions of polymeric membranes manufactured from various biocompatible polymers. Ionic permeability and water vapor transmission rate representing the barrier properties of these membranes were investigated. First results were obtained for polyimide, silicone, polyether ether ketone and polyamide, whereas polyimide evinced the best properties.

  15. Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

    NASA Technical Reports Server (NTRS)

    Cox, Sarah B.; Lui, Donovan; Gou, Jihua

    2014-01-01

    The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, which allows a shape to be formed prior to the cure, and is then pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Basalt fibers are used for the reinforcement in the composite system. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material.

  16. Synthesis and characterization of nanocomposite polymer blend electrolyte thin films by spin-coating method

    NASA Astrophysics Data System (ADS)

    Chapi, Sharanappa; Niranjana, M.; Devendrappa, H.

    2016-05-01

    Solid Polymer blend electrolytes based on Polyethylene oxide (PEO) and poly vinyl pyrrolidone (PVP) complexed with zinc oxide nanoparticles (ZnO NPs; Synthesized by Co-precipitation method) thin films have prepared at a different weight percent using the spin-coating method. The complexation of the NPs with the polymer blend was confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR). The variation in film morphology was examined by polarized optical micrographs (POMs). The thermal behavior of blends was investigated under non-isothermal conditions by differential thermal analyses (DTA). A single glass transition temperature for each blend was observed, which supports the existence of compatibility of such system. The obtained results represent that the ternary based thin films are prominent materials for battery and optoelectronic device applications.

  17. Synthesis and Characterization of Phosphonium-Containing Cationic Poly(styrene) Polymers

    DTIC Science & Technology

    2009-12-01

    ionomeric system designed as an anion exchange membrane for these types of applications. Styrene monomer has been copolymerized with 4... Ionomer , phophonium, cationic, RAFT, polymer 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 14 19a...drastically altered even at low phosphonium contents. Homopolymer poly(styrene) typically has a glass transition temperature (Tg) around 100 °C; low

  18. Experimental and Numerical Characterization of Polymer Nanocomposites for Solid Rocket Motor Internal Insulation

    DTIC Science & Technology

    2006-09-30

    a modeling framework for simulating the insulative behavior of thermoplastic Polyurethane elastomer nanocomposites (TPUNs) for solid rocket motors...Nanophase, Thermoplastic Elastomer, EPDM Rubber, Surface Modified MMT Clay, Carbon Nanofibers 16. SECURITY CLASSIFICATION OF: a. REPORT u b. ABSTRACT U...Third Year Program Tasks 7 4. Description of Polymer Nanocomposites 7 4.1 Thermoplastic Elastomer 7 4.2 Montmorilonite Nanoclays 7 4.3 Carbon

  19. Characterization of Highly Sulfonated SIBS Polymer Partially Neutralized With Mg(+2) Cations

    DTIC Science & Technology

    2008-08-01

    properties for chem-bio protective clothing. The major component of the triblock copolymer is polyisobutylene ( PIB ), which comprises 70% by weight of...the base polymer. The PIB gives the material low-temperature flexibility as well as excellent barrier properties. The polystyrene (PS) makes up 30...immiscibility of the two components results in a microphase separation where domains of PS are formed in the rubbery PIB matrix (5, 6). The fraction

  20. Synthesis of Hydroxy-Terminated Dinitropropyl Acrylate Polymers and Improved Characterization of Hydroxy-Terminated Prepolymers

    DTIC Science & Technology

    1983-03-01

    azelate polyesterdiol from Wittco PA Phthalic anhydride PCP Polycaprolactone diol from Union Carbide PDNPA Polydinitropropyl acrylate (our experimental... anhydride (AA) in the presence of N-methylimidazole (NMIM) (15)reported by Conners , and (b) phthalic anhydride (PA) in the presence of pyridine (PY...three meq sample of dried polymer was weighed into a 100 ml round bottom flask and 50 ml of phthalic anhydride stock solution (0.6 N) in anhydrous

  1. Characterization of fabricated three dimensional scaffolds of bioceramic-polymer composite via microstereolithography technique

    NASA Astrophysics Data System (ADS)

    Talib, Marina; Covington, James A.; Bolarinwa, Aminat

    2014-02-01

    Microstereolithography is a method used for rapid prototyping of polymeric and ceramic components. This technique converts a computer-aided design (CAD) to a three dimensional (3D) model, and enables layer per layer fabrication curing a liquid resin with UV-light or laser source. The aim of this project was to formulate photocurable polymer reinforced with synthesized calcium pyrophosphate (CPP), and to fabricate a 3D scaffolds with optimum mechanical properties for specific tissue engineering applications. The photocurable ceramic suspension was prepared with acrylate polyester, multifunctional acrylate monomer with the addition of 50-70wt% of CPP, photoinitiators and photoinhibitors. The 3D structure of disc (5 mm height × 4 mm diameter) was successfully fabricated using Envisiontec Perfactory3® . They were then sintered at high temperature for polymer removal, to obtain a ceramic of the desired porosity. The density increased to more than 35% and the dimensional shrinkage after sintering were 33%. The discs were then subjected compressive measurement, biodegradation and bioactivity test. Morphology and CPP content of the sintered polymer was investigated with SEM and XRD, respectively. The addition of CPP coupled with high temperature sintering, had a significant effect on the compressive strength exhibited by the bioceramic. The values are in the range of cancellous bone (2-4 MPa). In biodegradation and bioactivity test, the synthesized CPP induced the formation of apatite layer and its nucleation onto the composite surface.

  2. Synthesis, characterization, optical and electrical properties of bis(phenylvinyl)anthracene-based polymers

    NASA Astrophysics Data System (ADS)

    Mansour, Nadia; Hriz, Khaled; Jaballah, Nejmeddine; Kreher, David; Majdoub, Mustapha

    2016-08-01

    A series of bis(phenylvinyl)anthracene-based polymers containing different lengths of polar ethylene glycol groups in the main chain (P1-3) were efficiently synthesized by Wittig polycondensation. These polymers are fully soluble in volatile solvents, which helped a lot to obtain high quality films. Moreover, these semi-conducting materials exhibited semi-crystalline morphology with relatively high glass transition temperature. In this article, the UV-visible absorption and fluorescence properties of P1-3 were studied consequently both in solution and as thin solid film: tan absorption-onset at 433 nm was observed and all these bis(phenylvinyl)anthracene-based polymers (P1-3) show a blue emission in solution, fluorescence quantum efficiencies being respectively 52% for P1, 75% for P2 and 67% for P3. In addition, the HOMO/LUMO energy levels were evaluated by cyclic voltammetry measurements and indicate a p-type semi-conducting materials. Finally, the electrical properties of P1-3 were investigated by recording current-tension characteristics and these experimental results were modeled by the current space-charge-limited (SCLC) mechanism.

  3. Microstructural Characterization of Semi-Interpenetrating Polymer Networks by Positron Lifetime Spectroscopy

    NASA Technical Reports Server (NTRS)

    Singh, Jag J.; Pater, Ruth H.; Eftekhari, Abe

    1996-01-01

    Thermoset and thermoplastic polyimides have complementary physical and mechanical properties. Whereas thermoset polyimides are brittle and generally easier to process, thermoplastic polyimides are tough but harder to process. A combination of these two types of polyimides may help produce polymers more suitable for aerospace applications. Semi-Interpenetrating Polymer Networks (S-IPN) of thermoset LaRC(TM)-RP46 and thermoplastic LaRC(TM)-IA polyimides were prepared in weight percent ratios ranging from 100:0 to 0:100. Positron lifetime measurements were made in these samples to correlate their free volume features with physical and mechanical properties. As expected, positronium atoms are not formed in these samples. The second lifetime component has been used to infer the positron trap dimensions. The 'free volume' goes through a minimum at a ratio of about 50:50, and this suggests that S-IPN samples are not merely solid solutions of the two polymers. These data and related structural properties of the S-IPN samples are discussed.

  4. Mechanical characterization of an electrostrictive polymer for actuation and energy harvesting

    NASA Astrophysics Data System (ADS)

    Eddiai, A.; Meddad, M.; Touhtouh, S.; Hajjaji, A.; Boughaleb, Y.; Guyomar, D.; Belkhiat, S.; Sahraoui, B.

    2012-06-01

    Electroactive polymers have been widely used as smart material for actuators in recent years. Electromechanical applications are currently focused on energy harvesting and actuation, including the development of wireless portable electronic equipment autonomous and specific actuators such as artificial muscles. The problem to be solved is to make its devices the most efficient, as possible in terms of harvested energy and action. These two criteria are controlled by the permittivity of the electrostrictive polymer used, the Young's modulus, and their dependence on frequency and level of stress. In the present paper, we presented a model describing the mechanical behaviour of electrostrictive polymers with taking into account the mechanical losses. Young's modulus follows a linear function of strain and stress. However, when the elongation becomes higher, the data obtained from this strain linear trend and significant hysteresis loops appear the reflections on the existence of mechanical losses. In this work, to provide the analysis of the experimental observations, we utilized a theoretical model in order to define a constitutive law implying a representative relationship between stress and strain. After detailing this theoretical model, the simulation results are compared with experimental ones. The results show that hysteresis loss increases with the increase of frequency and strain amplitude. The model used here is in good agreement with the experimental results.

  5. Poling and characterization of a novel organic/polymer electro-optic material

    NASA Astrophysics Data System (ADS)

    Liao, Jinkun; Tang, Xianzhong; Lu, Rongguo; Tang, Xionggui; Li, Heping; Zhang, Xiaoxia; Liu, Yongzhi

    2010-10-01

    Electro-optic organic/polymer material is important for the fabrication of polymer integrated optic-electronic devices and organic sensors. Recently, a novel organic high μβ value chromophore FFC have been synthesized by molecular design. The absorption spectrum in 400-4000 cm-1 is measured for the material, and the measurement result shows that the absorption loss is negligibly small. An organic/polymer high electro-optic activity material FFC/PSU is obtained by dissolving guest FFC (wt. 20%) and a host polysulfone (PSU) in a solvent. The resolvability of cyclohexanone for the material is satisfactory by comparison with other solvents experimentally, and the preparation of FFC/PSU thin film is ease relatively. The materiel is poled by electric field-assisted contact poling, and the near optimum poling condition is determined by adjusting poling parameters as pre-curing duration, poling temperature and poling voltage etc. The electro-optic coefficient of the material is measured as high as 130pm/V by using the widely accepted simple reflection technique. The investigation indicates that the FFC/PSU has excellent characteristics, such as high electro-optic coefficient, low absorption loss, good thermal stability and capability for withstanding the subsequent process techniques, suitable for the fabrication of high-performance integrated optic-electronic devices and sensors.

  6. Synthesis and characterization of polymer-silica hybrid latexes and sol-gel-derived films

    NASA Astrophysics Data System (ADS)

    Petcu, Cristian; Purcar, Violeta; Ianchiş, Raluca; Spătaru, Cătălin-Ilie; Ghiurea, Marius; Nicolae, Cristian Andi; Stroescu, Hermine; Atanase, Leonard-Ionuţ; Frone, Adriana Nicoleta; Trică, Bogdan; Donescu, Dan

    2016-12-01

    Sol-gel derived organic-inorganic hybrid systems were obtained by applying alkaline-catalyzed co-hydrolysis and copolycondensation reactions of tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), isobutyltriethoxysilane (IBTES), diethoxydimethylsilane (DMDES), and vinyltriethoxysilane (VTES), respectively, into a polymer latex functionalized with vinyltriethoxysilane (VTES). The properties of the latex hybrid materials were analyzed by FTIR, water contact angle, environmental scanning electron microscopy (ESEM), TEM and AFM analysis, respectively. FT-IR spectra confirmed that the chemical structures of the sol-gel derived organic-inorganic materials are changed as function of inorganic precursor and Sisbnd Osbnd Si networks are formed during the co-hydrolysis and copolycondensation reactions. The water contact angle on the sol-gel latex film containing TEOS + VTES increased to 135° ± 2 compared to 65° ± 5 for the blank latex, due VTES incorporation into latex material. TGA curves of hybrid sample modifies against neat polymer, the thermal stability being influenced by the presence of the inorganic partner. ESEM analysis showed that the latex hybrid films prepared with different inorganic precursors were formed and the Si-based polymers were distributed on the surface of the dried sol-gel hybrid films. TEM and AFM photos revealed that the latex emulsion morphology was modified due to the VTES incorporation into system.

  7. Characterization of temperature-dependent optical material properties of polymer powders

    SciTech Connect

    Laumer, Tobias; Stichel, Thomas; Bock, Thomas; Amend, Philipp; Schmidt, Michael

    2015-05-22

    In former works, the optical material properties of different polymer powders used for Laser Beam Melting (LBM) at room temperature have been analyzed. With a measurement setup using two integration spheres, it was shown that the optical material properties of polymer powders differ significantly due to multiple reflections within the powder compared to solid bodies of the same material. Additionally, the absorption behavior of the single particles shows an important influence on the overall optical material properties, especially the reflectance of the powder bed. Now the setup is modified to allow measurements at higher temperatures. Because crystalline areas of semi-crystalline thermoplastics are mainly responsible for the absorption of the laser radiation, the influence of the temperature increase on the overall optical material properties is analyzed. As material, conventional polyamide 12 and polypropylene as new polymer powder material, is used. By comparing results at room temperature and at higher temperatures towards the melting point, the temperature-dependent optical material properties and their influence on the beam-matter interaction during the process are discussed. It is shown that the phase transition during melting leads to significant changes of the optical material properties of the analyzed powders.

  8. Fabrication and characterization of polymer blends and composites derived from biopolymers

    NASA Astrophysics Data System (ADS)

    Sharma, Suraj

    This research focuses on fabricating blends and composites from natural polymers especially from proteins and natural epoxy, and describing the properties of plastics made from them. Specifically, plastic samples from partially denatured feathermeal and bloodmeal proteins, derived from the animal co-products (rendering) industry, were successfully produced through a compression molding process. The modulus (stiffness) of the material obtained was found to be comparable with that of commercial synthetic materials, such as polystyrene, but was found to have lower toughness characteristics, which is a common phenomenon among plastics produced from animal and plant proteins. Therefore, this study explored blending methods for improving the toughness. Plastic forming conditions for undenatured animal proteins such as chicken egg whites albumin and whey, used as a model, were established to prepare plastics from their blends with animal co-product proteins. The resultant plastic samples from these biomacromolecular blends demonstrated improved mechanical properties that were also compared with the established theoretical models known for polymer blends and composites. Moreover, plastics from albumin of chicken egg whites and human serum have demonstrated their potential in medical applications that require antibacterial properties. Another natural polymer vegetable oil-based epoxy, especially epoxidized linseed oil, showed significant potential to replace petroleum-derived resins for use as a matrix for composites in structural applications. Moreover, the research showed the benefits of ultrasonic curing, which can help in preparing the out-of-autoclave composites.

  9. Characterization and dynamic charge dependent modeling of conducting polymer trilayer bending

    NASA Astrophysics Data System (ADS)

    Farajollahi, Meisam; Sassani, Farrokh; Naserifar, Naser; Fannir, Adelyne; Plesse, Cédric; Nguyen, Giao T. M.; Vidal, Frédéric; Madden, John D. W.

    2016-11-01

    Trilayer bending actuators are charge driven devices that have the ability to function in air and provide large mechanical amplification. The electronic and mechanical properties of these actuators are known to be functions of their charge state making prediction of their responses more difficult when they operate over their full range of deformation. In this work, a combination of state space representation and a two-dimensional RC transmission line model are used to implement a nonlinear time variant model for conducting polymer-based trilayer actuators. Electrical conductivity and Young’s modulus of electromechanically active PEDOT conducting polymer containing films as a function of applied voltage were measured and incorporated into the model. A 16% drop in Young’s modulus and 24 times increase in conductivity are observed by oxidizing the PEDOT. A closed form formulation for radius of curvature of trilayer actuators considering asymmetric and location dependent Young’s modulus and conductivity in the conducting polymer layers is derived and implemented in the model. The nonlinear model shows the capability to predict the radius of curvature as a function of time and position with reasonable consistency (within 4%). The formulation is useful for general trilayer configurations to calculate the radius of curvature as a function of time. The proposed electrochemical modeling approach may also be useful for modeling energy storage devices.

  10. Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

    NASA Technical Reports Server (NTRS)

    Cox, Sarah B.; Lui, Donovan; Gou, Jihua

    2014-01-01

    The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Polysiloxanes contain a silicon oxycarbide backbone when pyrolized up to 1000C. Polycarbosilane, an organosilicon polymer, contain a silicon-carbon backbone; around 1200C, beta-SiC begins to crystallize. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Basalt is a naturally occurring material found in volcanic rock. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. Thermal and mechanical testing includes oxyacetylene torch testing and three point bend testing.

  11. Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

    NASA Technical Reports Server (NTRS)

    Cox, Sarah B.; Lui, Donovan; Wang, Xin; Gou, Jihua

    2014-01-01

    The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Polysiloxanes contain a silicon oxycarbide backbone when pyrolized up to 1000 deg C. Polycarbosilane, an organosilicon polymer, contain a silicon-carbon backbone; around 1200 deg C, Beta-SiC begins to crystallize. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Basalt is a naturally occurring material found in volcanic rock. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. Thermal and mechanical testing includes oxyacetylene torch testing and three point bend testing.

  12. Processing and Material Characterization of Continuous Basalt Fiber Reinforced Ceramic Matrix Composites Using Polymer Derived Ceramics.

    NASA Technical Reports Server (NTRS)

    Cox, Sarah B.

    2014-01-01

    The need for high performance vehicles in the aerospace industry requires materials which can withstand high loads and high temperatures. New developments in launch pads and infrastructure must also be made to handle this intense environment with lightweight, reusable, structural materials. By using more functional materials, better performance can be seen in the launch environment, and launch vehicle designs which have not been previously used can be considered. The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Polymer matrix composites can be used for temperatures up to 260C. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in the composites. In this study, continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. The oxyacetylene torch testing and three point bend testing have been performed on test panels and the test results are presented.

  13. Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

    NASA Technical Reports Server (NTRS)

    Cox, Sarah; Lui, Donovan; Gou, Jihua

    2014-01-01

    The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed, to be cured, and be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Polysiloxanes contain a silicon oxycarbide backbone when pyrolized up to 1000degC. Polycarbosilane, an organosilicon polymer, contain a silicon-carbon backbone; around 1200degC, -SiC begins to crystallize. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Basalt is a naturally occurring material found in volcanic rock. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. Testing for this included thermal and mechanical testing per ASTM standard tests.

  14. Characterization of temperature-dependent optical material properties of polymer powders

    NASA Astrophysics Data System (ADS)

    Laumer, Tobias; Stichel, Thomas; Bock, Thomas; Amend, Philipp; Schmidt, Michael

    2015-05-01

    In former works, the optical material properties of different polymer powders used for Laser Beam Melting (LBM) at room temperature have been analyzed. With a measurement setup using two integration spheres, it was shown that the optical material properties of polymer powders differ significantly due to multiple reflections within the powder compared to solid bodies of the same material. Additionally, the absorption behavior of the single particles shows an important influence on the overall optical material properties, especially the reflectance of the powder bed. Now the setup is modified to allow measurements at higher temperatures. Because crystalline areas of semi-crystalline thermoplastics are mainly responsible for the absorption of the laser radiation, the influence of the temperature increase on the overall optical material properties is analyzed. As material, conventional polyamide 12 and polypropylene as new polymer powder material, is used. By comparing results at room temperature and at higher temperatures towards the melting point, the temperature-dependent optical material properties and their influence on the beam-matter interaction during the process are discussed. It is shown that the phase transition during melting leads to significant changes of the optical material properties of the analyzed powders.

  15. Preparation and characterization of nonfouling polymer brushes on poly(ethylene terephthalate) film surfaces.

    PubMed

    Li, Jiehua; Tan, Dongsheng; Zhang, Xiaoqing; Tan, Hong; Ding, Mingming; Wan, Changxiu; Fu, Qiang

    2010-07-01

    In this study, a surface grafting of nonfouling poly(ethylene glycol) methyl ether acrylate (PEGMA) on poly(ethylene terephthalate) (PET) was carried out via surface-initiated atom-transfer radical polymerization (SI-ATRP) to improve hemocompatibility of polymer based biomaterials. To do this, the coupling agent with hydroxyl groups for the ATRP initiator was first anchored on the surface of PET films using photochemical method, and then these hydroxyl groups were esterified by bromoisobutyryl bromide, from which PET with various main chain lengths of PEGMA was prepared. The structures and properties of modified PET surfaces were investigated using water contact angle (WAC), ATR-FTIR, X-ray photoelectron spectroscopy (XPS) and Atomic force microscopy (AFM). The molecular weights of the free polymer from solution were determined by gel permeation chromatography (GPC). These results indicated that grafting of PEGMA on PET film is a simple way to change its surface properties. The protein adsorption resistance on the surfaces of PET was primarily evaluated by an enzyme-linked immunosorbent assay (ELISA). The result demonstrated that the protein adsorption could be well suppressed by poly(PEGMA) brush structure on the surface of PET. This work provides a new approach for polymers to enhance their biocompatibility.

  16. Pine-polyethylene (wood-polymer) composites: Synthesis and mechanical behavior characterization

    NASA Astrophysics Data System (ADS)

    Razi, Parviz S.

    Processing of recycled wood chips, recently produced after extraction of creosote from telephone posts and railroad crossties, and combining them with a recycled polymer for the synthesis of novel composite materials would initiate a new trend toward preservation of natural resources. The challenge is taken in this work to produce and study the properties of such materials for further advancement of science. In the present study, addition of pine wood chips to HDPE reduced the tensile strength and break strain in tensile loading. Smaller wood chips generally resulted in smaller reductions. Peak load, modulus of rupture and stiffness were slightly higher at 40% pine wood chip concentration in the composite than the polymer alone; they later decreased with increasing concentration of wood chips. Optimal mechanical properties in these composites were produced by pine wood chips smaller than 0.125 inch in size, at around 40 vol. % in concentration. Pre-treatment of wood chips in a suitable solution of NaOH caused an increase in the coupling strength between protruding wood fibers and polymer. Such a treatment followed by a second one with vinyltrimethoxysilane was found to be the best for obtaining maximum bonding strength. Impact testing of the prepared samples showed that more fracture resistant wood-polymer composites were those with larger wood chips at the higher concentration range of 50 to 60 vol. %. In contrast, composites with 60% fine wood chips would fail easily at energy levels far less than those required to break the polymer alone. Variation of (Keng)2/E vs. crack length, the R curve, indicates three regions. The point of transition from region I (elastic) to region II is considered as a critical point of fracture process initiation, KIif,com. The transition from the state of stable crack growth, region II, to region III is considered to be at the point of instability. Likewise, the point of inflection on the plot of Ktrue vs. crack length, corresponding

  17. Surface and bulk characterization of an ultrafine South African coal fly ash with reference to polymer applications

    NASA Astrophysics Data System (ADS)

    van der Merwe, E. M.; Prinsloo, L. C.; Mathebula, C. L.; Swart, H. C.; Coetsee, E.; Doucet, F. J.

    2014-10-01

    South African coal-fired power stations produce about 25 million tons of fly ash per annum, of which only approximately 5% is currently reused. A growing concern about pollution and increasing landfill costs stimulates research into new ways to utilize coal fly ash for economically beneficial applications. Fly ash particles may be used as inorganic filler in polymers, an application which generally requires the modification of their surface properties. In order to design experiments that will result in controlled changes in surface chemistry and morphology, a detailed knowledge of the bulk chemical and mineralogical compositions of untreated fly ash particles, as well as their morphology and surface properties, is needed. In this paper, a combination of complementary bulk and surface techniques was explored to assess the physicochemical properties of a classified, ultrafine coal fly ash sample, and the findings were discussed in the context of polymer application as fillers. The sample was categorized as a Class F fly ash (XRF). Sixty-two percent of the sample was an amorphous glass phase, with mullite and quartz being the main identified crystalline phases (XRD, FTIR). Quantitative carbon and sulfur analysis reported a total bulk carbon and sulfur content of 0.37% and 0.16% respectively. The spatial distribution of the phases was determined by 2D mapping of Raman spectra, while TGA showed a very low weight loss for temperatures ranging between 25 and 1000 °C. Individual fly ash particles were characterized by a monomodal size distribution (PSD) of spherical particles with smooth surfaces (SEM, TEM, AFM), and a mean particle size of 4.6 μm (PSD). The BET active surface area of this sample was 1.52 m2/g and the chemical composition of the fly ash surface (AES, XPS) was significantly different from the bulk composition and varied considerably between spheres. Many properties of the sample (e.g. spherical morphology, small particle size, thermal stability) appeared

  18. Synthesis and characterization of β-cyclodextrin functionalized ionic liquid polymer as a macroporous material for the removal of phenols and As(V).

    PubMed

    Raoov, Muggundha; Mohamad, Sharifah; Abas, Mhd Radzi

    2013-12-23

    β-Cyclodextrin-ionic liquid polymer (CD-ILP) was first synthesized by functionalized β-cyclodextrin (CD) with 1-benzylimidazole (BIM) to form monofunctionalized CD (βCD-BIMOTs) and was further polymerized using a toluene diisocyanate (TDI) linker to form insoluble CD-ILP (βCD-BIMOTs-TDI). The βCD-BIMOTs-TDI polymer was characterized using various tools and the results obtained were compared with those derived from the native β-cyclodextrin polymer (βCD-TDI). The SEM result shows that the presence of ionic liquid (IL) increases the pore size, while the thermo gravimetric analysis (TGA) result shows that the presence of IL increases the stability of the polymer. Meanwhile, Brunauer-Emmett-Teller (BET) results show that βCD-BIMOTs-TDI polymer has 1.254 m(2)/g surface areas and the Barret-Joyner-Halenda (BJH) pore size distribution result reveals that the polymer exhibits macropores with a pore size of 77.66 nm. Preliminary sorption experiments were carried out and the βCD-BIMOTs-TDI polymer shows enhanced sorption capacity and high removal towards phenols and As(V).

  19. Synthesis and Characterization of β-Cyclodextrin Functionalized Ionic Liquid Polymer as a Macroporous Material for the Removal of Phenols and As(V)

    PubMed Central

    Raoov, Muggundha; Mohamad, Sharifah; Abas, Mhd Radzi

    2014-01-01

    β-Cyclodextrin-ionic liquid polymer (CD-ILP) was first synthesized by functionalized β-cyclodextrin (CD) with 1-benzylimidazole (BIM) to form monofunctionalized CD (βCD-BIMOTs) and was further polymerized using a toluene diisocyanate (TDI) linker to form insoluble CD-ILP (βCD-BIMOTs-TDI). The βCD-BIMOTs-TDI polymer was characterized using various tools and the results obtained were compared with those derived from the native β-cyclodextrin polymer (βCD-TDI). The SEM result shows that the presence of ionic liquid (IL) increases the pore size, while the thermo gravimetric analysis (TGA) result shows that the presence of IL increases the stability of the polymer. Meanwhile, Brunauer-Emmett-Teller (BET) results show that βCD-BIMOTs-TDI polymer has 1.254 m2/g surface areas and the Barret-Joyner-Halenda (BJH) pore size distribution result reveals that the polymer exhibits macropores with a pore size of 77.66 nm. Preliminary sorption experiments were carried out and the βCD-BIMOTs-TDI polymer shows enhanced sorption capacity and high removal towards phenols and As(V). PMID:24366065

  20. Characterization of particle morphology of biochanin A molecularly imprinted polymers and their properties as a potential sorbent for solid-phase extraction.

    PubMed

    Chrzanowska, Anna M; Poliwoda, Anna; Wieczorek, Piotr P

    2015-04-01

    Molecularly imprinted polymers (MIPs) with biochanin A as a template were obtained using a bulk polymerization with non-covalent imprinting approach. The polymers were prepared in acetonitrile as porogen, using ethylene glycol dimethacrylate (EDMA) as cross-linking agent. The synthesis, with an application of 1',1'-azobis(cyclohexanecarbonitrile) (ACHN) as an initiator, has been performed thermally. During the synthesis process the effect of different functional monomers such as methacrylic acid (MAA), acrylamide (AA) and 4-vinylpyridine (4-VP) was investigated. The application of nitrogen sorption porosimetry, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) permitted the characterization and evaluation of synthesized polymers. The adsorption capacity of obtained MIPs was checked by using the binding testing. All synthesized polymers were evaluated as solid-phase extraction (SPE) sorbents for isolation and preconcentration of biochanin A and its analogues, daidzein and genistein. The MIPs exhibited higher affinity for biochanin A over competitive compounds.

  1. Preparation and Characterization of Biomimetic Hydroxyapatite-Resorbable Polymer Composites for Hard Tissue Repair

    NASA Astrophysics Data System (ADS)

    Hiebner, Kristopher Robert

    Autografts are the orthopedic "gold standard" for repairing bone voids. Autografts are osteoconductive and do not elicit an immune response, but they are in short supply and require a second surgery to harvest the bone graft. Allografts are currently the most common materials used for the repair of segmental defects in hard tissue. Unlike autografts, allografts can cause an undesirable immune response and the possibility of disease transmission is a major concern. As an alternative to the above approaches, recent research efforts have focused on the use of composite materials made from hydroxyapatite (HA) and bioresorbable polymers, such as poly-L-lactide (PLLA). Recent results have shown that the surface hydroxides on HA can initiate the ring opening polymerization (ROP) of L-lactide and other lactones creating a composite with superior interfacial strength. This thesis demonstrates that the surface of porous biologically derived HA substrates, such as coralline HA and trabecular bone, can be used to initiate the ROP of L-lactide and other lactones from the vapor phase. This process increases the strength of the porous scaffold through the deposition of a thin, uniform polymer coating, while maintaining the porous structure. The kinetics of the chemical vapor deposition polymerization (CVDP) are described using a quartz crystal microbalance (QCM). The reaction temperature and monomer vapor pressure are found to affect the rate of the polymerization. Also described in this thesis is the preparation of a porous polymer scaffold that mimics the structure of demineralized bone matrix (DBM). This demineralized bone matrix simulant (DBMS) is created using anorganic bovine bone as a template to initiate the polymerization of various lactones, followed by the removal of the HA scaffold. This material retained its shape and exhibits mechanical properties superior to DBM. Finally it is shown that HA can be used to initiate the ROP of a-caprolactam and the biocompatibility

  2. Learning from nature: synthesis and characterization of longitudinal polymer gradient materials inspired by mussel byssus threads.

    PubMed

    Claussen, Kai U; Giesa, Reiner; Scheibel, Thomas; Schmidt, Hans-Werner

    2012-02-13

    Marine mussels use their threads for attachment to any substratum and these biopolymer gradient fibers show an excellent combination of stiff and soft mechanical properties. A straightforward approach for the preparation of macroscopic longitudinal polymer gradient materials on the centimeter scale based on a poly(dimethyl siloxane) system is presented. Compositional gradients are realized by using three syringe pumps feeding different prepolymers capable to undergo thermal cross-linking. Within the gradient samples, the stiffness between the hard and soft part can be varied up to a factor of four. The gradients are analyzed by UV-Vis spectroscopy as well as compressive and tensile modulus testing.

  3. Synthesis and characterization of 1D iron(II) spin crossover coordination polymers with hysteresis.

    PubMed

    Bauer, Wolfgang; Lochenie, Charles; Weber, Birgit

    2014-02-07

    Purposeful ligand design was used for the synthesis of eight new 1D iron(II) spin crossover coordination polymers aiming for cooperative spin transitions with hysteresis. The results from magnetic measurements and X-ray structure analysis show that the combination of rigid linkers and a hydrogen bond network between the 1D chains is a promising tool to reach this goal. Five of the eight new samples show a cooperative spin transition with hysteresis with up to 43 K wide hysteresis loops.

  4. Fabrication and characterization of novel polymer-matrix nanocomposites and their constituents

    NASA Astrophysics Data System (ADS)

    Ding, Rui

    Two main issues for the wide application of polymer-matrix nanocomposites need to be addressed: cost-effective processing of high-performance nanomaterials, and fundamental understanding of the nanofiller-polymer interaction related to property changes of nanocomposites. To fabricate inexpensive and robust carbon nanofibers (CNFs) by the electrospinning technique, an organosolv lignin for replacing polyacrylonitrile (PAN) precursor was investigated in this work. Modification of lignin to its butyl ester alters the electrospinnability and the thermal mobility of the lignin/PAN blend precursor fibers, which further affect the thermostabilization and carbonization processes of CNFs. The micromorphology, carbon structure, and mechanical properties of resultant CNFs were evaluated in detail. Lignin butyration reveals a new approach to controlling inter-fiber bonding of CNFs which efficiently increases the tensile strength and modulus of nonwoven mats. A commercial vapor-grown CNF reinforcing of room-temperature-vulcanized (RTV) polysiloxane foam has potential impact on the residual tin catalyst in composites and consequently the aging and the long-term performance of the materials. Elemental spectra and mapping were employed to analyze the distribution and the composition of tin catalyst residues in the CNF/polysiloxane composites. Thermal analysis revealed a significant increase of thermal stability for CNF-filled composites. Further, the glass transition properties of polysiloxane are not evidently influenced by the physical interaction between CNF filler and polysiloxane matrix. Nanocomposites consisting of anthracene, a model polycyclic aromatic hydrocarbon (PAH) compound, and a thermosetting epoxy was matrix was studied to interpret the reinforcing effect on the glass transition temperature ( Tg) by different routes: physical dispersion and/or covalent modification. The molecular dynamics of the relaxation processes were analyzed by broadband dielectric

  5. Simulation and experimental characterization of polymer/carbon nanotubes composites for strain sensor applications

    NASA Astrophysics Data System (ADS)

    De Vivo, B.; Lamberti, P.; Spinelli, G.; Tucci, V.; Vertuccio, L.; Vittoria, V.

    2014-08-01

    In this paper, a numerical model is presented in order to analyze the electrical characteristics of polymer composites filled by carbon nanotubes (CNTs) subject to tensile stress and investigate the possible usage of such materials as innovative sensors for small values of strain. The simulated mechano-electrical response of the nanocomposite is obtained through a multi-step approach which, through different modeling stages, provides a simple and effective tool for material analysis and design. In particular, at first, the morphological structures of the composites are numerically simulated by adopting a previously presented model based on a Monte Carlo procedure in which uniform distributions of the CNTs, approximated as of solid cylinders and ensuring some physical constraints, are dispersed inside a cubic volume representing the polymer matrix. Second, a geometrical analysis allows to obtain the percolation paths detected in the simulated structures. Suitable electrical networks composed by resistors and capacitors associated to the complex charge transport and polarization mechanisms occurring in the percolation paths are then identified. Finally, the variations of these circuit parameters, which are differently affected by the mechanical stresses applied to the composites, are considered to analyze the electromechanical characteristics of the composites and hence their performances as stress sensors. The proposed approach is used to investigate the impact on the electro-mechanical response of some physical properties of the base materials, such as the type of carbon nanotube, the height of energy barrier of polymer resin, as well as characteristics of the composite, i.e., the volume fraction of the filler. The tunneling effect between neighboring nanotubes is found to play a dominant role in determining the composite sensitivity to mechanical stresses. The simulation results are also compared with the experimental data obtained by performing stress tests on

  6. Conducting Polymer Nanostructures and Nanocomposites with Carbon Nanotubes: Hierarchical Assembly by Molecular Electrochemistry, Growth Aspects and Property Characterization.

    PubMed

    Gupta, Sanju; Price, Carson; Heintzman, Eli

    2016-01-01

    Conducting (or π-conjugated) polymers are promising materials for preparing supramolecular nano-structures and nanocomposites. We report controlled nanostructure syntheses of polypyrrole (PPy) and poylaniline (PANi) via electropolymerization (i.e., in-situ electrochemical anodic oxidation). The density, shape, caliber and thickness of self-assembled PPy micro-containers are regulated by electrochemical potential window for H2 bubbles and number of cyclic voltammetric (potentiodynamic) scans. Likewise, we employed amperometry, chronopotentiometry and potentiodynamic modes using hydrochloric acid as oxidizing agent to prepare PANi nanoparticles and nanotubules. We present our findings from the viewpoint of molecular electrochemistry with growth kinetic aspects yielding mechanistic details (initially forming dimers and oligomers as nucleating agents followed by polymer growth). Also targeted is forming nanocomposites with functionalized single- and multi-walled carbon nanotubes (FSWCNTs and FMWCNTs) as reinforced agent to optimize structural and functional properties. All of these novel nanomaterials are characterized using a range of complementary techniques to establish microscopic structure-property-function relationship.

  7. Mechanical characterization of thin film, water-based polymer gels through simple tension testing of laminated bilayers.

    PubMed

    Krone, Ryan; Havenstrite, Karen; Shafi, Bilal

    2013-11-01

    We present a method of characterizing the nonlinear stress-strain behavior of thin films of extremely soft, water-based polymer gels using uniaxial tension testing of bilayer laminates, in conjunction with methods of membrane nonlinear elasticity. A custom tensile testing apparatus is used to conduct quasi-static, uniaxial extension tests of narrow strips of thin, laminated sheets of bonded hydrogel and silicone rubber, submerged in a saline bath. The tensile load is measured via sensitive load cell and the position of material markers, at a central test-section of the sample, is optically tracked via digital image tracking methods. Stress-strain relationships are calculated for the hydrogel component of the bilayer, considered hyperelastic, homogeneous, isotropic, and incompressible, using membrane theories of finite hyperelasticity. We present the stress response for strains up to about 35% for poly(ethylene glycol) (PEG)-based hydrogels (>90% water) with polymer concentrations by weight of 5% to 10%. Polynomial functions are fit to the data for each formulation, whereby the one-dimensional strain-energy function for each formulation is determined by taking the indefinite integral.

  8. The fractal calibration method applied to the characterization of polymers in solvent mixtures and in mixed gel packings by SEC.

    PubMed

    Porcar, Iolanda; García-Lopera, Rosa; Abad, Concepción; Campos, Agustín

    2007-08-01

    The size-exclusion chromatographic (SEC) behaviour of different solvent/polymer systems in three packing sets has been analysed from fractal considerations. The three-column sets studied are specifically formed by: (i) 'pure' micro-styragel, (ii) 'mixed' TSK Gel H(HR + XL + HR) and (iii) mixed TSK Gel H(XL + HR + XL). The experimental data reveals that in most of the systems assayed the classical universal calibration (UC) is not fulfilled, denoting the existence of secondary effects accompanying the main SEC mechanism. In order to obtain an accurate characterization of different polymers eluted in solvent mixtures and/or mixed packings, the use of a reliable and trusted calibration curve is required. In this sense, two alternative procedures have been analysed: the specific (SC) and the fractal (FC) calibrations. The results have evidenced that the use of the FC instead of the classical universal method diminishes up to nine times (in the case of the micro-styragel set) the mean deviation on the calculated molar mass with respect to the value given by the supplier. In the case of TSK Gel-based sets, the mean deviation is reduced to the half. The SC curve made with standards of the sample under study also reduces the mean deviation values but needs a broad set of narrow standards, whereas the fractal approach only needs one polymeric sample to build up the calibration curve.

  9. Preparation and characterization, stable bismaleimide-triarylamine polymers with reversible electrochromic properties.

    PubMed

    Zhang, Haiyang; Niu, Haijun; Ji, Yan; Wu, Wenjun; Cai, Jiwei; Wang, Cheng; Lian, Yongfu; Bai, Xuduo; Wang, Wen

    2013-07-01

    A series of novel polyimides were synthesized from bismaleimide containing different diaminetriarylamines by Michael addition reaction. The prepolymer is readily soluble in many common organic solvents, such as CHCl3, Tetrahydrofuran (THF) and N, N-dimethyl formamide (DMF). Prepolymers can be solution-cast into transparent, tough, and flexible films. These aromatic polyimides display good thermal stabilities, i.e. 5% weight-loss temperatures in excess of 200 °C under nitrogen. All obtained polyimides revealed excellent stability of electrochromic characteristics, changing color from original yellowish to green. The energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of the investigated the polymers were estimated by experimental method are in the range of -4.78 eV to -4.98 eV and -1.64 eV to -2.09 eV vs the vacuum level, respectively. All the polymer films reveal good electrochemical and electrochromic stability under repeatedly switching electrode voltages, with coloration change from the yellow neutral state to green oxidized state.

  10. Preparation and characterization, stable bismaleimide-triarylamine polymers with reversible electrochromic properties

    NASA Astrophysics Data System (ADS)

    Zhang, Haiyang; Niu, Haijun; Ji, Yan; Wu, Wenjun; Cai, Jiwei; Wang, Cheng; Lian, Yongfu; Bai, Xuduo; Wang, Wen

    2013-07-01

    A series of novel polyimides were synthesized from bismaleimide containing different diaminetriarylamines by Michael addition reaction. The prepolymer is readily soluble in many common organic solvents, such as CHCl3, Tetrahydrofuran (THF) and N, N-dimethyl formamide (DMF). Prepolymers can be solution-cast into transparent, tough, and flexible films. These aromatic polyimides display good thermal stabilities, i.e. 5% weight-loss temperatures in excess of 200 °C under nitrogen. All obtained polyimides revealed excellent stability of electrochromic characteristics, changing color from original yellowish to green. The energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of the investigated the polymers were estimated by experimental method are in the range of -4.78 eV to -4.98 eV and -1.64 eV to -2.09 eV vs the vacuum level, respectively. All the polymer films reveal good electrochemical and electrochromic stability under repeatedly switching electrode voltages, with coloration change from the yellow neutral state to green oxidized state.

  11. Characterization of interfaces in Binary and Ternary Polymer Blends by Positron Lifetime Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ranganathaiah, C.

    2015-06-01

    A miscible blend is a single-phase system with compact packing of the polymeric chains/segments due configuration/conformational changes upon blending. Differential Scanning Calorimetry (DSC) is the most employed method to ascertain whether the blend is miscible or immiscible. Positron Lifetime Spectroscopy (PLS) has been employed in recent times to study miscibility properties of polymer blends by monitoring the ortho-Positronium annihilation lifetimes as function of composition. However, just free volume monitoring and the DSC methods fail to provide the composition dependent miscibility of blends. To overcome this limitation, an alternative approach based on hydrodynamic interactions has been developed to derive this information using the same o-Ps lifetime measurements. This has led to the development of a new method of measuring composition dependent miscibility level in binary and ternary polymer blends. Further, the new method also provides interface characteristics for immiscible blends. The interactions between the blend components has a direct bearing on the strength of adhesion at the interface and hence the hydrodynamic interaction. Understanding the characteristic of interfaces which decides the miscibility level of the blend and their end applications is made easy by the present method. The efficacy of the present method is demonstrated for few binary and ternary blends.

  12. miktoarm polymer: controlled synthesis, characterization, and application as anticancer drug carrier

    NASA Astrophysics Data System (ADS)

    Lin, Wenjing; Nie, Shuyu; Xiong, Di; Guo, Xindong; Wang, Jufang; Zhang, Lijuan

    2014-05-01

    Amphiphilic A2(BC)2 miktoarm star polymers [poly(ɛ-caprolactone)]2-[poly(2-(diethylamino)ethyl methacrylate)- b- poly(poly(ethylene glycol) methyl ether methacrylate)]2 [(PCL)2(PDEA- b-PPEGMA)2] were developed by a combination of ring opening polymerization (ROP) and continuous activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP). The critical micelle concentration (CMC) values were extremely low (0.0024 to 0.0043 mg/mL), depending on the architecture of the polymers. The self-assembled empty and doxorubicin (DOX)-loaded micelles were spherical in morphologies, and the average sizes were about 63 and 110 nm. The release of DOX at pH 5.0 was much faster than that at pH 6.5 and pH 7.4. Moreover, DOX-loaded micelles could effectively inhibit the growth of cancer cells HepG2 with IC50 of 2.0 μg/mL. Intracellular uptake demonstrated that DOX was delivered into the cells effectively after the cells were incubated with DOX-loaded micelles. Therefore, the pH-sensitive (PCL)2(PDEA- b-PPEGMA)2 micelles could be a prospective candidate as anticancer drug carrier for hydrophobic drugs with sustained release behavior.

  13. Morphological Characterization of a Low-Bandgap Crystalline Polymer: PCBM Bulk Heterojunction Solar Cells

    SciTech Connect

    Lu, Haiyun; Akgun, Bulent; Russell, Thomas P.

    2011-07-01

    Understanding the morphology of polymer-based bulk heterojunction (BHJ) solar cells is necessary to improve device efficiencies. Blends of a low-bandgap silole-containing conjugated polymer, poly[(4,4'-bis(2-ethylhexyl)dithieno[3,2-b;2',3'-d]silole)-2,6-diyl-alt-(4,7-bis(2-thienyl)-2,1,3-benzothiadiazole)-5,5'-diyl] (PSBTBT) with [6,6]phenyl-C61-butyric acid methyl ester (PCBM) were investigated under different processing conditions. The surface morphologies and vertical segregation of the “As-Spun”, “Pre-Annealed”, and “Post-Annealed” films were studied by scanning force microscopy, contact angle measurements, X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, dynamic secondary ion mass spectrometry, and neutron reflectivity. The results showed that PSBTBT was enriched at the cathode interface in the “As-Spun” films and thermal annealing increased the segregation of PSBTBT to the free surface, while thermal annealing after deposition of the cathode increased the PCBM concentration at the cathode interface. Grazing-incidence X-ray diffraction and small-angle neutron scattering showed that the crystallization of PSBTBT and segregation of PCBM occurred during spin coating, and thermal annealing increased the ordering of PSBTBT and enhanced the segregation of the PCBM, forming domains ~10 nm in size, leading to an improvement in photovoltaic performance.

  14. Ammonium across a Selective Polymer Inclusion Membrane: Characterization, Transport, and Selectivity.

    PubMed

    Casadellà, Anna; Schaetzle, Olivier; Loos, Katja

    2016-05-01

    The recovery of ammonium from urine requires distinguishing and excluding sodium and potassium. A polymer inclusion membrane selective for ammonium is developed using an ionophore based on pyrazole substituted benzene. The interactions of the components are studied, as well as their effect on transport and selectivity. Spectroscopic and thermogravimetric measurements show no extensive physical interactions of the components, and that the plasticizer reduces the intermolecular forces (rigidity) of the membrane. The ionophore turns the membrane more rigid, although it increases its swelling degree and therefore the affinity of cations. A ratio of plasticizer (DEHP) and polymer (PVC) of 1:3 in mass gives the highest ammonium flux. Tested contents of ionophore (2 and 5 wt%) show that the higher the content of the ionophore, the fastest the flux is (7.5 × 10(-3) mmol cm(-2) h(-1) ). Selectivity of NH4 (+) over Na(+) and over K(+) is reduced from 13.07 to 9.33 and from 14.15 to 9.57 correspondingly.

  15. Characterization of poly(3,4-ethylenedioxythiophene):tosylate conductive polymer microelectrodes for transmitter detection.

    PubMed

    Larsen, Simon T; Vreeland, Richard F; Heien, Michael L; Taboryski, Rafael

    2012-04-21

    In this paper we investigate the physical and electrochemical properties of micropatterned poly(3,4-ethylenedioxythiophene):tosylate (PEDOT:tosylate) microelectrodes for neurochemical detection. PEDOT:tosylate is a promising conductive polymer electrode material for chip-based bioanalytical applications such as capillary electrophoresis, high-performance liquid chromatography, and constant potential amperometry at living cells. Band electrodes with widths down to 3 μm were fabricated on polymer substrates using UV lithographic methods. The electrodes are electrochemically stable in a range between -200 mV and 700 mV vs. Ag/AgCl and show a relatively low resistance. A wide range of transmitters is shown to oxidize readily on the electrodes. Kinetic rate constants and half wave potentials are reported. The capacitance per area was found to be high (1670 ± 130 μF cm(-2)) compared to other thin film microelectrode materials. Finally, we use constant potential amperometry to measure the release of transmitters from a group of PC 12 cells. The results show how the current response decreases for a series of stimulations with high K(+) buffer.

  16. Characterization of the attachment mechanisms of tissue-derived cell lines to blood-compatible polymers.

    PubMed

    Hoshiba, Takashi; Nikaido, Mayo; Tanaka, Masaru

    2014-05-01

    Recent advances in biomedical engineering require the development of new types of blood-compatible polymers that also allow non-blood cell attachment for the isolation of stem cells and circulating tumor cells (CTCs) from blood and for the development of artificial organs for use under blood-contact conditions. Poly(2-methoxyethyl acrylate) (PMEA) and poly(tetrafurfuryl acrylate) (PTHFA) were previously identified as blood-compatible polymers. Here, it is demonstrated that cancer cells can attach to the PMEA and PTHFA substrates, and the differences in the attachment mechanisms to the PMEA and PTHFA substrates between cancer cells and platelets are investigated. It is also found that the adsorption-induced deformation of fibrinogen, which is required for the attachment and activation of platelets, does not occur on the PMEA and PTHFA substrates. In contrast, fibronectin is deformed on the PMEA and PTHFA substrates. Therefore, it is concluded that cancer cells and not platelets can attach to the PMEA and PTHFA substrates based on this protein-deformation difference between these substrates. Moreover, it is observed that cancer cells attach to the PMEA substrate via both integrin-dependent and -independent mechanisms and attach to the PTHFA substrate only through an integrin-dependent mechanism. It is expected that PMEA and PTHFA will prove useful for blood-contact biomedical applications.

  17. Characterization of the Migration of Hop Volatiles into Different Crown Cork Liner Polymers and Can Coatings.

    PubMed

    Wietstock, Philip C; Glattfelder, Richard; Garbe, Leif-Alexander; Methner, Frank-Jürgen

    2016-04-06

    Absorption of hop volatiles by crown cork liner polymers and can coatings was investigated in beer during storage. All hop volatiles measured were prone to migrate into the closures, and the absorption kinetics was demonstrated to fit Fick's second law of diffusion well for a plane sheet. The extent and rate of diffusion were significantly dissimilar and were greatly dependent upon the nature of the volatile. Diffusion coefficients ranged from 1.32 × 10(-5) cm(2)/day (limonene) to 0.26 × 10(-5) cm(2)/day (α-humulene). The maximum amounts absorbed into the material at equilibrium were in the following order: limonene > α-humulene > trans-caryophyllene > myrcene ≫ linalool > α-terpineol > geraniol. With the application of low-density polyethylene (LDPE) liners with oxygen-scavenging functionality, oxygen-barrier liners made up from high-density polyethylene (HDPE) or liner polymers from a different manufacturer had no significant effect on the composition of hop volatiles in beers after prolonged storage of 55 days; however, significantly higher amounts of myrcene and limonene were found in the oxygen-barrier-type crown cork, while all other closures behaved similarly. Can coatings were demonstrated to absorb hop volatiles in a similar pattern as crown corks but to a lesser extent. Consequently, significantly higher percentages of myrcene were found in the beers.

  18. Preparation and characterization of branched polymers as postoperative anti-adhesion barriers

    NASA Astrophysics Data System (ADS)

    Way, Tzong-Der; Hsieh, Shih-Rong; Chang, Chi-Jung; Hung, Tsung-Wei; Chiu, Chun-Hwei

    2010-03-01

    Homopolymers and copolymers synthesized from biocompatible monomers with polyethylene glycol (PEG) and polycaprolactone side chains, were applied to separate healing tissues and prevent postsurgical adhesions. The results of the contact angle and the ESCA spectra reveal the presence of more PEG segments on the surface of the PEMC1 film than the P(EM) 3(EMC4) 1 film. The effects of the molecular structures on the surface properties, including the wetting properties and the anti-tissue adhesion behaviors, of the films were examined. Fluorescent polymer was fixed on the surface of the film to form the marking dot. The in vivo degradation behaviors of the surface-marked films were investigated non-invasively by monitoring the location of the fluorescent signal. The degradation behaviors of various films observed in the animal study were consistent with those observed by in vivo imaging. Proper arrangement of PEG segments on the polymer side chain helped to keep a large proportion of PEG segments close to the surface of the film. Such an arrangement represents an effective means of preventing postoperative tissue adhesion.

  19. Development and characterization of polymer-coated liposomes for vaginal delivery of sildenafil citrate.

    PubMed

    Refai, Hanan; Hassan, Doaa; Abdelmonem, Rehab

    2017-11-01

    Vaginal administration of sildenafil citrate has shown recently to develop efficiently the uterine lining with subsequent successful embryo implantation following in vitro fertilization. The aim of the present study was to develop sildenafil-loaded liposomes coated with bioadhesive polymers for enhanced vaginal retention and improved drug permeation. Three liposomal formulae were prepared by thin-film method using different phospholipid:cholesterol ratios. The optimal liposomal formulation was coated with bioadhesive polymers (chitosan and HPMC). A marked increase in liposomal size and zeta potential was observed for all coated liposomal formulations. HPMC-coated liposomes showed the greater bioadhesion and higher entrapment efficiency than chitosan-coated formulae. The in vitro release studies showed prolonged release of sildenafil from coated liposomes as compared to uncoated liposomes and sildenafil solution. Ex vivo permeation study revealed the enhanced permeation of coated relative to uncoated liposomes. Chitosan-coated formula demonstrated highest drug permeation and was thus selected for further investigations. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) confirmed the successful coating of the liposomes by chitosan. Histopathological in vivo testing proved the efficacy of chitosan-coated liposomes to improve blood flow to the vaginal endometrium and to increase endometrial thickness. Chitosan-coated liposomes can be considered as potential novel drug delivery system intended for the vaginal administration of sildenafil, which would prolong system's retention at the vaginal site and enhance the permeation of sildenafil to uterine blood circulation.

  20. Growth and characterization of polymer thin films grown using molecular layer deposition with heterobifunctional precursors

    NASA Astrophysics Data System (ADS)

    Gibbs, Zachary Michael Conway

    In this work, growth of thin polymer films using molecular layer deposition with heterobifunctional precursors is investigated. Several growth phenomena are observed including: loss or gain of reactive sites as a result of precursor reactivity or vapor pressure; precursor diffusion and reaction within the porous polymer film; and crosslinking. Reactions were investigated using quartz crystal microbalance, Fourier transform infrared spectroscopy, and various ex situ techniques. Reactions involving 4-azidophenylisothiocyanate and 4-aminobenzonitrile were shown to stop growth after only a few cycles which is attributed to a loss in reactive sites which was modeled by an exponentially decaying growth rate. Growth of 4-carboxyphenylisothiocyanate with TMA and water was investigated as well. Active site multiplication as a result of the trifunctionality of the TMA molecule was proposed to explain the significantly higher growth rate for TMA/CI films. TMA/H2O/CI films showed the ability to crosslink through aluminum hydroxyl condensation reactions. Upon increasing the reaction temperature, reactant diffusion was observed in the form of mass removal upon TMA exposure. This same phenomena is thought to be occurring in films grown using Diels-Alder reactions in the third section of this thesis. These films showed a strong growth rate dependence upon reactant purge time and growth temperature. FTIR seems to weakly support Diels-Alder reaction, but it appears that the primary film growth mechanism is through CVD-like diffusion and condensation reactions.

  1. Experimental and theoretical characterization of non-bending ionic polymer transducer sensing

    NASA Astrophysics Data System (ADS)

    Kocer, Bilge; Zangrilli, Ursula T.; Weiland, Lisa M.

    2012-04-01

    Ionic Polymer Transducers (IPTs) have both actuation and sensing capabilities. However, the electromechanical response of an IPT as a sensor is quite different from the response as an actuator. IPT sensors are not limited to bending, i.e., they also produce current for compressive, extensional, and shear deformations. A robust physical model must be able to predict the existence of a sensing signal in all modes of deformation. Such a model could subsequently be adapted to form a roadmap toward enhancing sensitivity. In this study, the objective is to experimentally define IPT sensing characteristics in shear deformation (non-bending) and compare the empirical results with predictions derived from a model based on the streaming potential hypothesis. An in-house displacement control rig is employed to establish empirical results in shear sensing. A finite element approach is employed in the companion model development. The IPTs considered employ Nafion as the ionic polymer layer, while the electrode includes high surface area ruthenium oxide, RuO2, metallic powder and deposited per the Direct Assembly Process.

  2. Preparation and characterization of plasticized palm-based polyurethane solid polymer electrolyte

    SciTech Connect

    Daud, Farah Nadia; Ahmad, Azizan; Badri, Khairiah Haji

    2013-11-27

    Palm-based polyurethane solid polymer electrolyte was prepared via prepolymerization method between palm kernel oil based polyols (PKO-p) and 2,4’-diphenylmethane diisocyanate (2,4’-MDI) in acetone at room temperature with the vary amount of lithium trifuoromethanesulfonate (LiCF{sub 3}SO{sub 3}) salt and polyethylene glycol (PEG). The film was analyzed using attenuated total reflection infrared (ATR-IR) spectroscopy, electrochemical impedance spectroscopy (EIS) and X-ray diffractometry (XRD). EIS result indicated ionic conductivity obtained with 30 wt% LiCF3SO3 increased to 6.55 × 10{sup −6} S cm{sup −1} when 10 wt.% of plasticizer was added into the system. FTIR analysis showed the interaction between lithium ions and amine (-N-H) at 3600–3100 cm{sup −1}, carbonyl (-C=O) at 1750–1650 cm{sup −1} and ether (-C-O-C-) at 1150–1000 cm{sup −1} of the polyurethane forming polymer-salt complexes. The XRD result confirmed that LiCF{sub 3}SO{sub 3} salt completely dissociated within the polyurethane film with the absence of crystalline peaks of LiCF{sub 3}SO{sub 3}.

  3. Stiffness, strength and adhesion characterization of electrochemically deposited conjugated polymer films

    PubMed Central

    Qu, Jing; Ouyang, Liangqi; Kuo, Chin-chen; Martin, David C.

    2015-01-01

    Conjugated polymers such as poly(3,4-ethylenedioxythiphene) (PEDOT) are of interest for a variety of applications including interfaces between electronic biomedical devices and living tissue. The mechanical properties, strength, and adhesion of these materials to solid substrates are all vital for long-term applications. We have been developing methods to quantify the mechanical properties of conjugated polymer thin films. In this study the stiffness, strength and the interfacial shear strength (adhesion) of electrochemically deposited PEDOT and PEDOT-co-1,3,5-tri[2-(3,4-ethylene dioxythienyl)]-benzene (EPh) were studied. The estimated Young’s modulus of the PEDOT films was 2.6 ± 1.4 GPa, and the strain to failure was around 2%. The tensile strength was measured to be 56 ± 27 MPa. The effective interfacial shear strength was estimated with a shear-lag model by measuring the crack spacing as a function of film thickness. For PEDOT on gold/palladium-coated hydrocarbon film substrates an interfacial shear strength of 0.7 ± 0.3 MPa was determined. The addition of 5 mole% of a tri-functional EDOT crosslinker (EPh) increased the tensile strength of the films to 283 ± 67 MPa, while the strain to failure remained about the same (2%). The effective interfacial shear strength was increased to 2.4 ± 0.6 MPa. PMID:26607768

  4. Broadband coherent anti-Stokes Raman spectroscopy characterization of polymer thin films.

    PubMed

    Schultz, Zachary D; Gurau, Marc C; Richter, Lee J

    2006-10-01

    Broadband coherent anti-Stokes Raman spectroscopy (CARS) is demonstrated as an effective probe of polymer thin film materials. A simple modification to a 1 kHz broad bandwidth sum frequency generation (SFG) spectrometer permits acquisition of CARS spectra for polymer thin films less than 100 nm thick, a dimension relevant to organic electronic device applications. CARS spectra are compared to the conventional Raman spectra of polystyrene and the resonance-enhanced Raman spectra of poly(3-hexylthiophene). The CARS spectra obtained under these conditions consistently demonstrate enhanced signal-to-noise ratio compared to the spontaneous Raman scattering. The sensitivity of the CARS measurement is limited by the damage threshold of the samples. The dielectic properties of the substrate have a dramatic effect on the detected signal intensity. For ultrathin films, the strongest signals are obtained from fused silica surfaces. Similar to surface-enhanced Raman scattering (SERS), Au also gives a large signal, but contrary to SERS, no surface roughening is necessary.

  5. Characterization of origami shape memory metamaterials (SMMM) made of bio-polymer blends

    NASA Astrophysics Data System (ADS)

    Kshad, Mohamed Ali E.; Naguib, Hani E.

    2016-04-01

    Shape memory materials (SMMs) are materials that can return to their virgin state and release mechanically induced strains by external stimuli. Shape memory polymers (SMPs) are a class of SMMs that show a high shape recoverability and which have attractive potential for structural applications. In this paper, we experimentally study the shape memory effect of origami based metamaterials. The main focus is on the Muira origami metamaterials. The fabrication technique used to produce origami structure is direct molding where all the geometrical features are molded from thermally virgin polymers without post folding of flat sheets. The study shows experimental investigations of shape memory metamaterials (SMMMs) made of SMPs that can be used in different applications such as medicine, robotics, and lightweight structures. The origami structure made from SMP blends, activated with uniform heating. The effect of blend composition on the shape memory behavior was studied. Also the influence of the thermomechanical and the viscoelastic properties of origami unit cell on the activation process have been discussed, and stress relaxation and shape recovery were investigated. Activation process of the unit cell has been demonstrated.

  6. Characterization of cationic polymers by asymmetric flow field-flow fractionation and multi-angle light scattering-A comparison with traditional techniques.

    PubMed

    Wagner, Michael; Pietsch, Christian; Tauhardt, Lutz; Schallon, Anja; Schubert, Ulrich S

    2014-01-17

    In the field of nanomedicine, cationic polymers are the subject of intensive research and represent promising carriers for genetic material. The detailed characterization of these carriers is essential since the efficiency of gene delivery strongly depends on the properties of the used polymer. Common characterization methods such as size exclusion chromatography (SEC) or mass spectrometry (MS) suffer from problems, e.g. missing standards, or even failed for cationic polymers. As an alternative, asymmetrical flow field-flow fractionation (AF4) was investigated. Additionally, analytical ultracentrifugation (AUC) and (1)H NMR spectroscopy, as well-established techniques, were applied to evaluate the results obtained by AF4. In this study, different polymers of molar masses between 10 and 120kgmol(-1) with varying amine functionalities in the side chain or in the polymer backbone were investigated. To this end, some of the most successful gene delivery agents, namely linear poly(ethylene imine) (LPEI) (only secondary amines in the backbone), branched poly(ethylene imine) (B-PEI) (secondary and tertiary amino groups in the backbone, primary amine end groups), and poly(l-lysine) (amide backbone and primary amine side chains), were characterized. Moreover, poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), poly(2-(amino)ethyl methacrylate) (PAEMA), and poly(2-(tert-butylamino)ethyl methacrylate) (PtBAEMA) as polymers with primary, secondary, and tertiary amines in the side chain, have been investigated. Reliable results were obtained for all investigated polymers by AF4. In addition, important factors for all methods were evaluated, e.g. the influence of different elution buffers and AF4 membranes. Besides this, the correct determination of the partial specific volume and the suppression of the polyelectrolyte effect are the most critical issues for AUC investigations.

  7. A cyanide-bridged heterometallic coordination polymer constructed from square-planar [Ni(CN)4](2-): synthesis, crystal structure, thermal decomposition, electron paramagnetic resonance (EPR) spectrum and magnetic properties.

    PubMed

    Qin, Ying Lian; Yang, Bin Wu; Wang, Gao Feng; Sun, Hong

    2016-07-01

    Square-planar complexes are commonly formed by transition metal ions having a d(8) electron configuration. Planar cyanometallate anions have been used extensively as design elements in supramolecular coordination systems. In particular, square-planar tetracyanometallate(II) ions, i.e. [M(CN)4](2-) (M(II) = Ni, Pd or Pt), are used as good building blocks for bimetallic Hofmann-type assemblies and their analogues. Square-planar tetracyanonickellate(II) complexes have been extensively developed with N-donor groups as additional co-ligands, but studies of these systems using O-donor ligands are scarce. A new cyanide-bridged Cu(II)-Ni(II) heterometallic compound, poly[[diaquatetra-μ2-cyanido-κ(8)C:N-nickel(II)copper(II)] monohydrate], {[Cu(II)Ni(II)(CN)4(H2O)2]·H2O}n, has been synthesized and characterized by X-ray single-crystal diffraction analyses, vibrational spectroscopy (FT-IR), thermal analysis, electron paramagnetic resonance (EPR) and magnetic moment measurements. The structural analysis revealed that it has a two-dimensional grid-like structure built up of cationic [Cu(H2O)2](2+) and anionic [Ni(CN)4](2-) units connected through bridging cyanide ligands. The overall three-dimensional supramolecular network is expanded by a combination of interlayer O-H...N and intralayer O-H...O hydrogen-bond interactions. The first decomposition reactions take place at 335 K under a static air atmosphere, which illustrates the existence of guest water molecules in the interlayer spaces. The electron paramagnetic resonance (EPR) spectrum confirms that the Cu(II) cation has an axial coordination symmetry and that the unpaired electrons occupy the d(x(2)-y(2)) orbital. In addition, magnetic investigations showed that antiferromagnetic interactions exist in the Cu(II) atoms through the diamagnetic [Ni(CN)4](2-) ion.

  8. Composite Materials Handbook. Volume 1. Polymer Matrix Composites Guidelines for Characterization of Structural Materials

    DTIC Science & Technology

    2007-11-02

    46 7.6.2 Adhesive characterization tests...50 7.6.2.4 Suggested adhesive characterization test matrix............................................ 50...7.5 Develop Adhesive Allowables, Volume 1, Section 7.6.2 Develop Bonded Joint Allowables, Volume 1, Section 7.6.3 Calculate Allowables and Design

  9. X-Ray-Based Imaging for Characterizing Heterogeneous Gas Diffusion Layers for Polymer Electrolyte Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    George, Michael G.

    Characterization of gas diffusion layers (GDLs) for polymer electrolyte membrane (PEM) fuel cells informs modeling studies and the manufacturers of next generation fuel cell materials. Identifying the physical properties related to the primary functions of the modern GDL (thermal, electrical, and mass transport) is necessary for understanding the impact of GDL design choices. X-ray micro-computed tomographic reconstructions of GDLs were studied to isolate GDL surface morphologies. Surface roughness was measured for a wide variety of samples and a sensitivity study highlighted the scale-dependence of surface roughness measurements. Furthermore, a spatially resolved distribution map of polytetrafluoroethylene (PTFE) in the microporous layer (MPL), critical for water management and mass transport, was identified and the existence of PTFE agglomerations was highlighted. Finally, the impact of accelerated degradation on GDL wettability and water transport increases in liquid water accumulation and oxygen mass transport resistance were quantified as a result of accelerated GDL degradation.

  10. An Effective On-line Polymer Characterization Technique by Using SALS Image Processing Software and Wavelet Analysis

    PubMed Central

    Xian, Guang-ming; Qu, Jin-ping; Zeng, Bi-qing

    2008-01-01

    This paper describes an effective on-line polymer characterization technique by using small-angle light-scattering (SALS) image processing software and wavelet analysis. The phenomenon of small-angle light scattering has been applied to give information about transparent structures on morphology. Real-time visualization of various scattered light image and light intensity matrices is performed by the optical image real-time processing software for SALS. The software can measure the signal intensity of light scattering images, draw the frequency-intensity curves and the amplitude-intensity curves to indicate the variation of the intensity of scattered light in different processing conditions, and estimate the parameters. The current study utilizes a one-dimensional wavelet to delete noise from the original SALS signal and estimate the variation trend of maximum intensity area of the scattered light. So, the system brought the qualitative analysis of the structural information of transparent film success. PMID:19229343

  11. Multilevel domain decomposition for electronic structure calculations

    SciTech Connect

    Barrault, M. . E-mail: maxime.barrault@edf.fr; Cances, E. . E-mail: cances@cermics.enpc.fr; Hager, W.W. . E-mail: hager@math.ufl.edu; Le Bris, C. . E-mail: lebris@cermics.enpc.fr

    2007-03-01

    We introduce a new multilevel domain decomposition method (MDD) for electronic structure calculations within semi-empirical and density functional theory (DFT) frameworks. This method iterates between local fine solvers and global coarse solvers, in the spirit of domain decomposition methods. Using this approach, calculations have been successfully performed on several linear polymer chains containing up to 40,000 atoms and 200,000 atomic orbitals. Both the computational cost and the memory requirement scale linearly with the number of atoms. Additional speed-up can easily be obtained by parallelization. We show that this domain decomposition method outperforms the density matrix minimization (DMM) method for poor initial guesses. Our method provides an efficient preconditioner for DMM and other linear scaling methods, variational in nature, such as the orbital minimization (OM) procedure.

  12. Physical characterization and in silico modeling of inulin polymer conformation during vaccine adjuvant particle formation.

    PubMed

    Barclay, Thomas G; Rajapaksha, Harinda; Thilagam, Alagu; Qian, Gujie; Ginic-Markovic, Milena; Cooper, Peter D; Gerson, Andrea; Petrovsky, Nikolai

    2016-06-05

    This study combined physical data from synchrotron SAXS, FTIR and microscopy with in-silico molecular structure predictions and mathematical modeling to examine inulin adjuvant particle formation and structure. The results show that inulin polymer chains adopt swollen random coil in solution. As precipitation occurs from solution, interactions between the glucose end group of one chain and a fructose group of an adjacent chain help drive organized assembly, initially forming inulin ribbons with helical organization of the chains orthogonal to the long-axis of the ribbon. Subsequent aggregation of the ribbons results in the layered semicrystalline particles previously shown to act as potent vaccine adjuvants. γ-Inulin adjuvant particles consist of crystalline layers 8.5 nm thick comprising helically organized inulin chains orthogonal to the plane of the layer. These crystalline layers alternate with amorphous layers 2.4 nm thick, to give overall particle crystallinity of 78%.

  13. Contact angle hysteresis on polymer substrates established with various experimental techniques, its interpretation, and quantitative characterization.

    PubMed

    Bormashenko, Edward; Bormashenko, Yelena; Whyman, Gene; Pogreb, Roman; Musin, Albina; Jager, Rachel; Barkay, Zahava

    2008-04-15

    The effect of contact angle hysteresis (CAH) was studied on various polymer substrates with traditional and new experimental techniques. The new experimental technique presented in the article is based on the slow deformation of the droplet, thus CAH is studied under the constant volume of the drop in contrast to existing techniques when the volume of the drop is changed under the measurement. The energy of hysteresis was calculated in the framework of the improved Extrand approach. The advancing contact angle established with a new technique is in a good agreement with that measured with the needle-syringe method. The receding angles measured with three experimental techniques demonstrated a very significant discrepancy. The force pinning the triple line responsible for hysteresis was calculated.

  14. Characterization of Thin Film Polymers Through Dynamic Mechanical Analysis and Permeation

    NASA Technical Reports Server (NTRS)

    Herring, Helen

    2003-01-01

    Thin polymer films are being considered, as candidate materials to augment the permeation resistance of cryogenic hydrogen fuel tanks such as would be required for future reusable launch vehicles. To evaluate performance of candidate films after environmental exposure, an experimental study was performed to measure the thermal/mechanical and permeation performance of six, commercial-grade materials. Dynamic storage modulus, as measured by Dynamic Mechanical Analysis, was found over a range of temperatures. Permeability, as measured by helium gas diffusion, was found at room temperature. Test data was correlated with respect to film type and pre-test exposure to moisture, elevated temperature, and cryogenic temperature. Results indicated that the six films were comparable in performance and their resistance to environmental degradation.

  15. [Characterization and soil environmental safety assessment of super absorbent polymers in agricultural application].

    PubMed

    Li, Xi; Liu, Yu-Rong; Zheng, Yuan-Ming; He, Ji-Zheng

    2014-01-01

    Super absorbent polymers (SAPs) are compounds that can absorb a lot of water which can be several folds of their original size and weight. They can increase soil water content and aggregates, promote fertilizer utilization efficiency, and stimulate crop growth. Therefore, SAPs have been widely regarded as a potential agent for water-saving agriculture. In this paper, we reviewed the advances of SAPs in materials, properties and applications in agriculture and pointed out that the absence of influences of SAPs on soil microbial ecology was the main issue in current studies. In regard to the adverse effects on soil environment caused by misuse of SAPs, we should address the systematic safety assessment of SAPs application in the soil, especially the effects on the soil microorganisms, which should be an important part of chemicals risk assessment in the soil application.

  16. Synthesis and characterization of asymmetric polymer/inorganic nanocomposites with pH/temperature sensitivity

    NASA Astrophysics Data System (ADS)

    Zhang, Xinjie; Gao, Chunmei; Liu, Mingzhu; Huang, Yinjuan; Yu, Xiyong; Ding, Enyong

    2013-01-01

    An easy, comprehensive and inexpensive method is demonstrated to produce asymmetric polymer/inorganic nanocomposites in a large quantity. With the aid of Pickering emulsion, unmodified particles aggregate on the surface of emulsion droplets and are fixed in place when the wax solidifies. The exposed surfaces of immobilized SiO2 particles are modified chemically by 2-(dimethylamino) ethylmethacrylate (DMAEMA). With the removal of wax, the exposed side of particles can be further modified chemically by N-isopropylacrylamide (NIPAAm). Based on these procedures, dual responsive asymmetric nanocomposite particles are achieved with both pH and temperature sensitivities. Due to their dual-stimuli and asymmetric structure, these particles have potential applications in molecule targeting, drug delivery and as building blocks for the assembly of complex nanostructure.

  17. Characterization of polymer composites by fiber optic Fourier transform Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Farquharson, Stuart; Bhat, Sanmitra A.; Osbaldiston, Richard; DiTaranto, Marie B.; Smith, Wayne W.; Rose, Jennifer; Liu, Yong-Ming; Shaw, Montgomery

    1999-01-01

    The in-use performance of polymer composites is highly dependent on the polymeric structure, which in turn, is highly dependent on the processing conditions. We have been developing a Fourier transform Raman system capable of high temperature measurements within curing devices through the use of fiber optic probes. The goal is to use real-time spectral data to control heat schedules and ultimately, composite properties. This presentation will describe the development of cure models based on reaction mechanisms for an epoxy resin and a polyimide using IR and Raman spectroscopy. It will also describe correlations between molecular structure and mechanical properties obtained by simultaneous Raman and rheology measurements. In addition, new spectral methods to determine cure kinetics will be presented.

  18. Characterization, molecular dynamics, and encapsulation ability of β-cyclodextrin polymers crosslinked by polyethylene glycol.

    PubMed

    Kono, Hiroyuki; Nakamura, Taichi; Hashimoto, Hisaho; Shimizu, Yuuichi

    2015-09-05

    A series of water-insoluble cyclodextrin polymers (CDP) was prepared by crosslinking β-cyclodextrin (CD) with polyethylene glycol diglycidyl ether (PEGDE). Similarly, a reference CDP was prepared using ethylene glycol diglycidyl ether (EGDE). Increasing the feed ratio of PEGDE to CD in the reaction mixture led to high degrees of crosslinking. Relaxation measurements revealed structural homogeneity among the CDPs, which exhibited mobilities that strongly depended on the chain lengths of the crosslinking agents. In addition, all the CDPs displayed high encapsulat