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. 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.

  5. 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.

  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. Aerobic Decomposition of Trialkylquercetins: Structure Characterization and Antiproliferative Effect.

    PubMed

    Al-Jabban, Sami M R; Zhang, Xiaojie; Chen, Guanglin; Rakotondraibe, Liva Harinantenaina; Chen, Qiao-Hong

    2016-04-01

    The aerobic decomposition of 3,4',7-O-trialkylquercetins was first reported in this paper. The structures of four new decomposed products were characterized by analyzing the 1D and 2D NMR data, as well as their high resolution mass spectroscopic data. Their antiproliferative activity toward human prostate cancer cells has been assessed through WST-l cell proliferation assay. The decomposition mechanism was also proposed.

  9. 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.

  10. 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.

  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

    USDA-ARS?s Scientific Manuscript database

    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. 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.

  14. 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.

  15. 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.

  16. Pollutant content in marine debris and characterization by thermal decomposition.

    PubMed

    Iñiguez, M E; Conesa, J A; Fullana, A

    2017-04-15

    Marine debris (MDs) produces a wide variety of negative environmental, economic, safety, health and cultural impacts. Most marine litter has a very low decomposition rate (plastics), leading to a gradual accumulation in the coastal and marine environment. Characterization of the MDs has been done in terms of their pollutant content: PAHs, ClBzs, ClPhs, BrPhs, PCDD/Fs and PCBs. The results show that MDs is not a very contaminated waste. Also, thermal decomposition of MDs materials has been studied in a thermobalance at different atmospheres and heating rates. Below 400-500K, the atmosphere does not affect the thermal degradation of the mentioned waste. However, at temperatures between 500 and 800K the presence of oxygen accelerates the decomposition. Also, a kinetic model is proposed for the combustion of the MDs, and the decomposition is compared with that of their main constituents, i.e., polyethylene (PE), polystyrene (PS), polypropylene (PP), nylon and polyethylene-terephthalate (PET). Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. 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.

  18. 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.

  19. Characterization of Nanostructured Polymer Films

    DTIC Science & Technology

    2014-12-23

    MAPLE- deposited polymer nanoglobules within the context of the Zhigilei model of target ablation in the MAPLE process. Molecular dynamics... vapor deposition . Figure 7: (a) Normalized volume of polymer nanodroplets and MAPLE- deposited nanoglobules as a function of temperature for...C.L. Sosa, C.B. Arnold, R.D. Priestley*, Patchy Janus Particles with Tunable Roughness and Composition via Vapor -Assisted Deposition of Macromolecules

  20. Preparation and characterization of beryllium doped organic plasma polymer coatings

    SciTech Connect

    Brusasco, R.; Letts, S.; Miller, P.; Saculla, M.; Cook, R.

    1995-10-04

    We report the formation of beryllium doped plasma polymerized coatings derived from a helical resonator deposition apparatus, using diethylberyllium as the organometaric source. These coatings had an appearance not unlike plain plasma polymer and were relatively stable to ambient exposure. The coatings were characterized by Inductively Coupled Plasma Mass Spectrometry and X-Ray Photoelectron Spectroscopy. Coating rates approaching 0.7 {mu}m hr{sup {minus}1} were obtained with a beryllium-to-carbon ratio of 1:1.3. There is also a significant oxygen presence in the coating as well which is attributed to oxidation upon exposure of the coating to air. The XPS data show only one peak for beryllium with the preponderance of the XPS data suggesting that the beryllium exists as BeO. Diethylberyllium was found to be inadequate as a source for beryllium doped plasma polymer, due to thermal decomposition and low vapor recovery rates.

  1. High-energy coordination polymers (CPs) exhibiting good catalytic effect on the thermal decomposition of ammonium dinitramide

    NASA Astrophysics Data System (ADS)

    Li, Xin; Han, Jing; Zhang, Sheng; Zhai, Lianjie; Wang, Bozhou; Yang, Qi; Wei, Qing; Xie, Gang; Chen, Sanping; Gao, Shengli

    2017-09-01

    High-energy coordination polymers (CPs) not only exhibit good energetic performances but also have a good catalytic effect on the thermal decomposition of energetic materials. In this contribution, two high-energy CPs Cu2(DNBT)2(CH3OH)(H2O)3·3H2O (1) and [Cu3(DDT)2(H2O)2]n (2) (H2DNBT = 3,3‧-dinitro-5,5‧-bis(1H-1,2,4-triazole and H3DDT = 4,5-bis(1H-tetrazol-5-yl)-2H-1,2,3-triazole) were synthesized and structurally characterized. Furthermore, 1 was thermos-dehydrated to produce Cu2(DNBT)2(CH3OH)(H2O)3 (1a). The thermal decomposition kinetics of 1, 1a and 2 were studied by Kissinger's method and Ozawa's method. Thermal analyses and sensitivity tests show that all compounds exhibit high thermal stability and low sensitivity for external stimuli. Meanwhile, all compounds have large positive enthalpy of formation, which are calculated as being (1067.67 ± 2.62) kJ mol-1 (1), (1464.12 ± 3.12) kJ mol-1 (1a) and (3877.82 ± 2.75) kJ mol-1 (2), respectively. The catalytic effects of 1a and 2 on the thermal decomposition of ammonium dinitramide (ADN) were also investigated.

  2. 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.

  3. Interfacial Characterization of Rigid Polymer Coatings

    NASA Astrophysics Data System (ADS)

    DeNolf, Garret C.

    In order to enhance the performance and durability of today's polymer coatings it is pivotal to be able to characterize their mechanical and chemical properties, with emphasized importance on coating-substrate interfaces which are common points of material failure. The purpose of this thesis was to develop and demonstrate novel characterization methods to measure the interfacial and bulk properties of these polymer films and improve the overall understanding of these materials. The first portion of this thesis explores a new peel test technique to measure the adhesion between substrates and coatings. The employed method examines the effect of processing conditions and substrate treatment on the adhesion of polyurethane coatings. This technique successfully quantifies the adhesion of polyurethane coatings to a variety of treated substrates and at multiple curing temperatures. The second thrust of this thesis involves the utilization of a quartz crystal microbalance instrument to characterize the bulk rheological properties of polymer films and coatings in situ. This novel method enables the examination of the effect of temperature and mixing stoichiometry on the rheological properties of curing polyurethane coatings and polymer films. This analysis is extended to measure the curing and aging of paint systems relevant to the art conservation scientific community. The final portion of this thesis focuses on understanding the effect of pH on the interfacial swelling of polymer films in aqueous environments. The quartz crystal microbalance is used to characterize the swelling of interfacial polymer films as water reaches the interface, and the corresponding permeability and osmotic pressure provides insight into the mechanisms of delamination and adhesive failure of coatings attached to metal surfaces. The novel methods and calculations established in this thesis enable precise measurements of coating interfaces and rheological properties and have considerable potential

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. APFIM characterization of the spinodal decomposition in duplex stainless steels

    SciTech Connect

    Brown, J.E.; Smith, G.D.W. . Dept. of Materials); Pumphrey, P.H. . Technology and Environment Centre); Miller, M.K. )

    1991-01-01

    An atom probe field ion microscope characterization of two CF3 steels with 15 and 25 volume percent ferrite aged at 400{degrees}C for up to 10,000 h and service materials from the Shippingport main and check valves aged for approximately 13 years at {approximately}280{degrees}C has been performed. In all these materials, the ferrite phase was found to have decomposed into an ultrafine scale two phase microstructure consisting of an iron-rich {alpha} phase and a chromium-enriched {alpha}{prime} phase. The scale of the decomposition in the Shippingport materials was much finer that than found in the CF3 material subjected to accelerated aging at 400{degrees}C. 20 refs., 9 figs., 3 tabs.

  9. 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.

  10. 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.

  11. Mechanical characterization of active polymer gels

    NASA Astrophysics Data System (ADS)

    Marra, Steven P.; Ramesh, Kaliat T.; Douglas, Andrew S.

    2000-06-01

    Ionic polymer gels shrink and swell in response to certain environmental stimuli, such as the application of an electric field or a change in the pH level of the surroundings. This ability to achieve large, reversible deformations with no external mechanical loading has generated much interest in the use of these gels as actuators and artificial muscles. This work focuses on developing a means of characterizing the mechanical properties of such ionic gels and describing how these properties evolve as the gel actuates. A thermodynamically consistent finite elastic constitutive model of an active polymer gel is developed to describe this behavior. The mechanical properties of the gel are characterized by a strain-energy function and the model utilizes an evolving internal variable to describe the actuation state. Applications of the mode to poly(vinyl alcohol)-poly (acrylic acid) gels are presented.

  12. 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.

  13. 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.

  14. Kinetic parameters for thermal decomposition of supramolecular polymers derived from diclofenac-meglumine supramolecular adducts.

    PubMed

    Cassimiro, Douglas L; Ferreira, Leonardo M B; Capela, Jorge M V; Crespi, Marisa S; Ribeiro, Clóvis A

    2013-01-25

    Meglumine is an aminocarbohydrate able to form supramolecular adducts with organic acids. The recognition is based on hydrogen bonds and the structures resulting from the complexation have high solubility in water. This property has been exploited by the pharmaceutical industry in the improvement of existing drugs, and the successful example of this approach involves the poorly soluble non-steroidal anti-inflammatory drugs (NSAIDs). Investigation of the thermal behavior of adduct obtained from meglumine and the NSAID diclofenac revealed that a polymer-like material is formed from the self-assembly of diclofenac-meglumine adducts in the melt. This polymer showed a high molecular weight around 2.0×10(5)kDa. The kinetic parameters for the thermal decomposition step of the polymer were determined by the Capela-Ribeiro non-linear isoconversional method. From data for the TG curves in nitrogen atmosphere and heating rates of 5, 10, 15 and 20°Cmin(-1), the E(α) and B(α) terms could be determined, and consequently the pre-exponential factor, A(α), as well as the kinetic model, g(α). Copyright © 2012 Elsevier B.V. All rights reserved.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Evaluation of different bioremediation protocols to enhance decomposition of organic polymers in harbour sediments.

    PubMed

    Gallizia, Ilaria; Vezzulli, Luigi; Fabiano, Mauro

    2005-12-01

    The response of the microbial community (in term of abundance and enzymatic activity) was investigated to test the effect of different bioremediation protocols to naturally enhance decomposition of organic polymers in harbour sediments (Genoa Harbour, Italy, N-W Mediterranean). Bioremediation techniques tested were bioaugmentation (5 different microorganisms' inocula), biostimulation (air supply), and natural attenuation. The coupling bioaugmentation/biostimulation was also tested. After 60 days, following the bioaugmentation protocol, bacterial densities correlated to the quantities of inocula amended to the boxes, suggesting that allochthonous community was able to survive and multiply. However, while bioaugmentation alone seems not to be able to carry out significative degradation, its coupling with air insufflations produced the best response: here bacterial densities increased, especially in the water (from 2.3 x 10(7) to 3.50 x 10(8) cells ml(-1)), average cell size and enzymatic activities increased, and sedimentary organic matter was significantly depleted (PRT 5-folds reduction, CHO 1.5-folds reduction). The strong coupling observed between the sediment and water compartments together with the greatest microbial response observed in this latter suggest that the sediment-water interface may constitute a key compartment for the occurring of biodegradation processes in organic-rich sediments.

  5. Characterization of passive polymer optical waveguides

    NASA Astrophysics Data System (ADS)

    Joehnck, Matthias; Kalveram, Stefan; Lehmacher, Stefan; Pompe, Guido; Rudolph, Stefan; Neyer, Andreas; Hofstraat, Johannes W.

    1999-05-01

    The characterization of monomode passive polymer optical devices fabricated according to the POPCORN technology by methods originated from electron, ion and optical spectroscopy is summarized. Impacts of observed waveguide perturbations on the optical characteristics of the waveguide are evaluated. In the POPCORN approach optical components for telecommunication applications are fabricated by photo-curing of liquid halogenated (meth)acrylates which have been applied on moulded thermoplastic substrates. For tuning of waveguide material refractive indices with respect to the substrate refractive index frequently comonomer mixtures are used. The polymerization characteristics, especially the polymerization kinetics of individual monomers, determine the formation of copolymers. Therefore the unsaturation as function of UV-illumination time in the formation of halogenated homo- and copolymers has been examined. From different suitable copolymer system, after characterization of their glass transition temperatures, their curing behavior and their refractive indices as function of the monomer ratios, monomode waveguides applying PMMA substrates have been fabricated. To examine the materials composition also in the 6 X 6 micrometers 2 waveguides they have been visualized by transmission electron microscopy. With this method e.g. segregation phenomena could be observed in the waveguide cross section characterization as well. The optical losses in monomode waveguides caused by segregation and other materials induce defects like micro bubbles formed as a result of shrinkage have been quantized by return loss measurements. Defects causing scattering could be observed by convocal laser scanning microscopy and by conventional light microscopy.

  6. 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.

  7. 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.

  8. Mössbauer study of the thermal decomposition of lepidocrocite and characterization of the decomposition products

    NASA Astrophysics Data System (ADS)

    de Bakker, P. M. A.; de Grave, E.; Vandenberghe, R. E.; Bowen, L. H.; Pollard, R. J.; Persoons, R. M.

    1991-08-01

    The lepidocrocite (γ-FeOOH) to maghemite (γ-Fe2O3), and the maghemite to hematite (α-Fe2O3) transition temperatures have been monitored by TGA and DSC measurements for four initial γ-FeOOH samples with different particle sizes. The transition temperature of γ-FeOOH to γ-Fe2O3 and the size of the resulting particles were not affected by the particle size of the parent lepidocrocite. In contrast, the γ-Fe2O3 to γ-Fe2O3 transition temperature seems to depend on the amount of excess water molecules present in the parent lepidocrocite. Thirteen products obtained by heating for one hour at selected temperatures, were considered. Powder X-ray diffraction was used to qualify their composition and to determine their mean crystallite diameters. Transmission electron micrographs revealed the particle morphology. The Mössbauer spectra at 80 K and room temperature of the mixed and pure decomposition products generally had to be analyzed with a distribution of hyperfine fields and, where appropriate, with an additional quadrupole-splitting distribution. The Mössbauer spectra at variable temperature between 4.2 and 400 K of two single-phase γ-Fe2O3 samples with extremely small particles show the effect of superparamagnetism over a very broad temperature range. Only at the lowest temperatures (T⩽55 K), two distributed components were resolved from the magnetically split spectra. In the external-field spectra the ΔmI=0 transitions have not vanished. This effect is an intrinsic property of the maghemite particles, indicating a strong spin canting with respect to the applied-field direction. The spectra are successfully reproduced using a bidimensional-distribution approach in which both the canting angle and the magnetic hyperfine field vary within certain intervals. The observed distributions are ascribed to the defect structure of the maghemites (unordered vacancy distribution on B-sites, large surface-to-bulk ratio, presence of OH- groups). An important new finding

  9. Recycle polymer characterization and adhesion modeling

    NASA Astrophysics Data System (ADS)

    Holbery, James David

    Contaminants from paper product producers that adversely affect fiber yield have been collected from mills located in three North American geographic regions. Samples have been fractionated using a modified solvent extraction process and subsequently quantitatively characterized and it was found that agglomerates were comprised of the following: approximately 30% extractable polymeric material, 25--35% fiber, 12--15% inorganic material, 15% non-extractable high molecular-weight polyethylene or cross-linked polymers, and 2--4% starch residue. Three representative polymers, paraffin, low-molecular weight polyethylene, and a commercial hot-melt adhesive were selected for further analysis to model the attractive and repulsive behavior using Scanning Probe Microscopy in an aqueous cell. Scanning force probes were characterized using an original technique utilizing a nano-indentation apparatus that is non-destructive and is accurate to within 10% for probes with force constants as low as 1 N/m. Surface force measurements were performed between a Poly (Styrene/30% Butyl Methacrylate) sphere and substrates produced from paraffin, polyethylene, and a commercial hot-melt adhesive in solutions ranging in NaF ionic concentrations from 0.001M to 1M. Reasonable theoretical agreement with experimental data has been shown between a combined model applying van der Waals force contributions using the Derjaguin approximation and electrostatic contributions as predicted by a Debye-Huckel linearization of the Poisson-Boltzmann equation utilizing Hamaker constants derived from critical surface energies determined from Zisman and Lifshitz-van der Waals energy approaches. This model has been applied to measured data and indicates the strength of adhesion for the hot-melt to be 0.14 nN while that of paraffin is 1.9 nN and polyethylene 2.8 nN. Paraffin and polyethylene are 13.5 and 20 times greater in attraction than the hot-melt adhesive. Hot-melt adhesive repulsion is predicted to be 220

  10. 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}.

  11. 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)

  12. Characterization and Selection of Polymer Materials for Binary Munitions Storage. Part 2. Characterization of LLDPE Resins.

    DTIC Science & Technology

    1984-07-01

    23,100 161,700 367,000 7.00 8. BILLMEYER , F. W., Jr. Characterization of Molecular Weight Distributions in High Polvmers. J. Polym. Sci., C8, 1965, p...161. 9. BILLMEYER , F. W., Jr. Testbook of Polymer Science. Wiley Intcrscience. New York, Ch. 3, 1971. 10. WILLIAMS, D. J. Polymer Science and

  13. 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.

  14. 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.

  15. On submodule characterization and decomposition of modules over group rings

    NASA Astrophysics Data System (ADS)

    Uc, Mehmet; Alkan, Mustafa

    2017-07-01

    In this paper, for a commutative unity ring R and a finite group G, we characterize some submodule properties of RG- module MG introduced in [8]. Our aim is to decompose MG into RG-submodules by defining an idempotent in EndRG MG and to verify the relation between the quotient of group module and the quotient of related module.

  16. 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.

  17. 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. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. 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.

  19. 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.

  20. Char characterization-thermal decomposition chemistry of poly(vinyl alcohol)

    SciTech Connect

    Gilman, J.W.; VanderHart, D.L.; Kashiwagi, Takashi

    1995-12-01

    Currently, due to concerns over the environmental effects of halogenated compound, there is an international demand for the control of polymer flammability without the use of halogenated additives. An alternative to the use of halogenated fire retardants, which control flammability primarily in the gas phase, is to control polymer flammability by manipulating the condensed phase chemistry. Our approach is to increase the amount of char that forms during polymer combustion. Char formation reduces, through crosslinking reactions, the amount of small volatile polymer pyrolysis fragments, or fuel, available for burning in the gas phase; this, in turn reduces the amount of heat feedback to the polymer surface. The char also insulates the underlying virgin polymer. The polymer we chose to investigate was polyvinyl alcohol, PVA, because it is one of the few linear, non-halogenated, aliphatic, polymers with a measurable (approximately 4%) char yield. We report the CP/MAS {sup 13}C NMR characterization of the fundamental condensed phase processes and structures which lead to char formation during the pyrolysis of poly (vinyl-alcohol), PVA, and PVA with nonhalogenated additives.

  1. 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.

  2. 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. Copyright © 2011 Elsevier B.V. All rights reserved.

  3. 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

  4. 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.

  5. 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.

  6. Electrospinning polymer nanofibers - Electrical and optical characterization

    NASA Astrophysics Data System (ADS)

    Khan, Saima N.

    Electro spinning is a technique used for the production of thin continuous fibers from a variety of materials including polymers, composites and ceramics [1-3]. The extremely small diameters (˜nm) and high surface to volume and aspect ratios found in electrospun fibers can not be achieved through conventional spinning. Electrically conducting polymers are materials which simultaneously possess the physical and chemical properties of organic polymers and the electronic characteristics of metals. In this work fibers were electrospun from polymer blends of polyaniline doped with Camphorsulfonic acid (PAn.HCSA) and polyethylene oxide (PEO) in chloroform. Electrical conductivities of the fibers were measured using the four-point-probe method. The conductivities of the cast films were measured for comparison purposes. It was noticed that the conductivity of both the fibers and films increase exponentially with the concentration of (PAn.HCSA), the conductivity of the film however is higher than that of the mat for any given concentration of PAn.HCSA in PEO. Electrical conductivities of single fibers containing different PAn: HCSA concentrations were measured for the first time and were found to be the highest (3.2S/cm) among the mats and films. The effect of the non-conductive PEO on the conductivity of the polyaniline fibers was studied. Keeping the PAn.HCSA concentration constant films and fibers were obtained from blends containing PEO (300,000 g/mol) and PEO (900,000 g/mol). Higher electrical conductivities were recorded in fibers and mats containing PEO (900,000 g/mol) than those containing PEO (300,000 g/mol). Silicon Carbide (SiC) fibers were obtained by electrospinning a blend of SiC and PEO in chloroform and sintering the as spun fibers at temperatures of 800°C and 1000°C. The compositional analysis of the annealed samples confirmed the presence of (30-40) mum long SiC fibers with diameters in the range (1-3) mum. Optical spectra of the fibers show red

  7. 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.

  8. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. 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.

  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 plasticized PEO-PAM blend polymer electrolyte system

    NASA Astrophysics Data System (ADS)

    Dave, Gargi; Kanchan, Dinesh

    2017-05-01

    Present study reports characterization studies of NaCF3SO3 based PEO-PAM Blend Polymer Electrolyte (BPE) system with varying amount of EC+PC as plasticizer prepared by solution cast technique. Structural analysis and surface topography have been performed using FTIR and SEM studies. To understand, thermal properties, DSC studies have been undertaken in the present paper

  12. Structural characterization of semicrystalline polymer morphologies by imaging-SANS

    NASA Astrophysics Data System (ADS)

    Radulescu, A.; Fetters, L. J.; Richter, D.

    2012-02-01

    Control and optimization of polymer properties require the global knowledge of the constitutive microstructures of polymer morphologies in various conditions. The microstructural features can be typically explored over a wide length scale by combining pinhole-, focusing- and ultra-small-angle neutron scattering (SANS) techniques. Though it proved to be a successful approach, this involves major efforts related to the use of various scattering instruments and large amount of samples and the need to ensure the same crystallization kinetics for the samples investigated at various facilities, in different sample cell geometries and at different time intervals. With the installation and commissioning of the MgF2 neutron lenses at the KWS-2 SANS diffractometer installed at the Heinz Maier-Leibnitz neutron source (FRMII reactor) in Garching, a wide Q-range, between 10-4Å-1 and 0.5Å-1, can be covered at a single instrument. This enables investigation of polymer microstructures over a length scale from lnm up to 1μm, while the overall polymer morphology can be further examined up to 100μm by optical microscopy (including crossed polarizers). The study of different semi-crystalline polypropylene-based polymers in solution is discussed and the new imaging-SANS approach allowing for an unambiguous and complete structural characterization of polymer morphologies is presented.

  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. 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.

  15. The hemocompatibility of a nitric oxide generating polymer that catalyzes S-nitrosothiol decomposition in an extracorporeal circulation model

    PubMed Central

    Major, Terry C.; Brant, David O.; Burney, Charles P.; Amoako, Kagya A.; Annich, Gail M.; Meyerhoff, Mark E.; Handa, Hitesh; Bartlett, Robert H.

    2011-01-01

    Nitric oxide (NO) generating (NOGen) materials have been shown previously to create localized increases in NO concentration by the catalytic decomposition of blood S-nitrosothiols (RSNO) via copper (Cu)-containing polymer coatings and may improve extracorporeal circulation (ECC) hemocompatibility. In this work, a NOGen polymeric coating composed of a Cuo-nanoparticle (80 nm)-containing hydrophilic polyurethane (SP-60D-60) combined with the intravenous infusion of an RSNO, S-nitroso-N-acetylpenicillamine (SNAP), is evaluated in a 4 h rabbit thrombogenicity model and the anti-thrombotic mechanism is investigated. Polymer films containing 10 wt.% Cuo-nanoparticles coated on the inner walls of ECC circuits are employed concomitantly with systemic SNAP administration (0.1182 μmol/kg/min) to yield significantly reduced ECC thrombus formation compared to polymer control + systemic SNAP or 10 wt.% Cu NOGen + systemic saline after 4 h blood exposure (0.4 ± 0.2 NOGen/SNAP vs 4.9 ± 0.5 control/SNAP or 3.2 ± 0.2 pixels/cm2 NOGen/saline). Platelet count (3.9 ± 0.7 NOGen/SNAP vs 1.8 ± 0.1 control/SNAP or 3.0 ± 0.2 × 108/ml NOGen/saline) and plasma fibrinogen levels were preserved after 4 h blood exposure with the NOGen/SNAP combination vs either the control/SNAP or the NOGen/saline groups. Platelet function as measured by aggregometry (51 ± 9 NOGen/SNAP vs 49 ± 3% NOGen/saline) significantly decreased in both the NOGen/SNAP and NOGen/saline groups while platelet P-selectin mean fluorescence intensity (MFI) as measured by flow cytometry was not decreased after 4 h on ECC to ex vivo collagen stimulation (26 ± 2 NOGen/SNAP vs 29 ± 1 MFI baseline). Western blotting showed that fibrinogen activation as assessed by Aγ dimer expression was reduced after 4 h on ECC with NOGen/SNAP (68 ± 7 vs 83 ± 3% control/SNAP). These results suggest that the NOGen polymer coating combined with SNAP infusion preserves platelets in blood exposure to ECCs by attenuating activated

  16. 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.

  17. 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.

  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. 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

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2017-10-01

    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.

  3. 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.

  4. 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.

  5. Characterization and Cu sorption properties of humic acid from the decomposition of rice straw.

    PubMed

    Qi, Yongbo; Zhu, Jun; Fu, Qingling; Hu, Hongqing; Rong, Xingmin; Huang, Qiaoyun

    2017-09-01

    Humic acid (HA) derived from rice straw decomposed for 1 (HA-1), 3 (HA-3), 6 (HA-6) and 12 (HA-12) months was characterized by potentiometric titration and solid-state cross-polarization magic-angle spinning (13)C nuclear magnetic resonance spectroscopy (CPMAS (13)C NMR). The sorption of Cu on examined HA was investigated using a combination of batch sorption, isothermal titration calorimetry (ITC) and sequential desorption. Results showed that the functional group content and the humification degree of HA tended to increase with increasing decomposition time especially in the latter stage of examined decomposition period. Cu sorption on HA was a rapid process that occurred within the first 1 h and the sorption capacity increased from 245.4 mmol kg(-1) on HA-1 to 294.6 mmol kg(-1) on HA-12. The sorption of Cu was endothermic, spontaneous and the randomness was increased during Cu sorption. Sorbed Cu on examined HA can be hardly released by NH4Ac but nearly fully released by EDTA. Forming inner-sphere complexes was the main mechanism of Cu sorption on examined HA. This study could provide valuable information for a better understanding on the environmental impacts of the decomposition of organic waste.

  6. A domain decomposition parallel processing algorithm for molecular dynamics simulations of polymers

    NASA Astrophysics Data System (ADS)

    Brown, David; Clarke, Julian H. R.; Okuda, Motoi; Yamazaki, Takao

    1994-10-01

    We describe in this paper a domain decomposition molecular dynamics algorithm for use on distributed memory parallel computers which is capable of handling systems containing rigid bond constraints and three- and four-body potentials as well as non-bonded potentials. The algorithm has been successfully implemented on the Fujitsu 1024 processor element AP1000 machine. The performance has been compared with and benchmarked against the alternative cloning method of parallel processing [D. Brown, J.H.R. Clarke, M. Okuda and T. Yamazaki, J. Chem. Phys., 100 (1994) 1684] and results obtained using other scalar and vector machines. Two parallel versions of the SHAKE algorithm, which solves the bond length constraints problem, have been compared with regard to optimising the performance of this procedure.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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

  20. Synthesis, characterization and non-isothermal decomposition kinetics of manganese hypophosphite monohydrate

    NASA Astrophysics Data System (ADS)

    Noisong, Pittayagorn; Danvirutai, Chanaiporn; Srithanratana, Tipaporn; Boonchom, Banjong

    2008-11-01

    The manganese hypophosphite monohydrate (α-Mn(H 2PO 2) 2·H 2O) was synthesized and characterized by differential thermal analysis-thermogravimetry (TG/DTG/DTA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The thermal transformation products form the synthesized Mn(H 2PO 2) 2·H 2O according to the thermal treatment at 160 and 450 °C were found to be α-Mn(H 2PO 2) 2· xH 2O and Mn 2P 2O 7, respectively. The activation energies of two decomposition reaction steps of Mn(H 2PO 2) 2·H 2O were calculated through the isoconversional methods of Ozawa and KAS. The obtained activation energies can be concluded that the reactions of the dehydration and the decomposition steps for Mn(H 2PO 2) 2·H 2O were the single and multi-step mechanisms, respectively.

  1. 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

  2. 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.

  3. Polymer planar waveguide Bragg gratings: fabrication, characterization, and sensing applications

    NASA Astrophysics Data System (ADS)

    Rosenberger, M.; Hessler, S.; Pauer, H.; Girschikofsky, M.; Roth, G. L.; Adelmann, B.; Woern, H.; Schmauss, B.; Hellmann, R.

    2017-02-01

    In this contribution, we give a comprehensive overview of the fabrication, characterization, and application of integrated planar waveguide Bragg gratings (PPBGs) in cyclo-olefin copolymers (COC). Starting with the measurement of the refractive index depth profile of integrated UV-written structures in COC by phase shifting Mach-Zehnder- Interferometry, we analyze the light propagation using numerical simulations. Furthermore, we show the rapid fabrication of humidity insensitive polymer waveguide Bragg gratings in cyclo-olefin copolymers and discuss the influence of the UV-dosage onto the spectral characteristics and the transmission behavior of the waveguide. Based on these measurements we exemplify that our Bragg gratings exhibit a reflectivity of over 99 % and are highly suitable for sensing applications. With regard to a negligible affinity to absorb water and in conjunction with high temperature stability these polymer devices are ideal for mechanical deformation sensing. Since planar structures are not limited to tensile but can also be applied for measuring compressive strain, we manufacture different functional devices and corroborate their applicability as optical sensors. Exemplarily, we highlight a temperature referenced PPBG sensor written into a femtosecond-laser cut tensile test geometry for tensile and compressive strain sensing. Furthermore, a flexible polymer planar shape sensor is presented.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Characterization of Local Mechanical Properties of Polymer Thin Films and Polymer Nanocomposites via AFM indentations

    NASA Astrophysics Data System (ADS)

    Cheng, Xu

    AFM indentation has become a tool with great potential in the characterization of nano-mechanical properties of materials. Thanks to the nanometer sized probes, AFM indentation is capable of capturing the changes of multiple properties within the range of tens of nanometers, such task would otherwise be difficult by using other experiment instruments. Despite the great potentials of AFM indentation, it operates based on a simple mechanism: driving the delicate AFM probe to indent the sample surface, and recording the force-displacement response. With limited information provided by AFM indentation, efforts are still required for any practice to successfully extract the desired nano-scale properties from specific materials. In this thesis, we focus on the mechanical properties of interphase between polymer and inorganic materials. It is known that in nanocomposites, a region of polymer exist around nanoparticles with altered molecular structures and improved properties, which is named as interphase polymer. The system with polymer thin films and inorganic material substrates is widely used to simulate the interphase effect in nanocomposites. In this thesis, we developed an efficient and reliable method to process film/substrate samples and characterize the changes of local mechanical properties inside the interphase region with ultra-high resolution AFM mechanical mapping technique. Applying this newly developed method, the interphase of several film/substrate pairs were examined and compared. The local mechanical properties on the other side of the polymer thin film, the free surface side, was also investigated using AFM indentation equipped with surface modified probes. In order to extract the full spectrum of local elastic modulus inside the surface region in the range of only tens of nanometers, the different contact mechanics models were studied and compared, and a Finite Element model was also established. Though the film/substrate system has been wide used as

  9. 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.

  10. Comparative study of differential matrix and extended polar decomposition formalisms for polarimetric characterization of complex tissue-like turbid media.

    PubMed

    Kumar, Satish; Purwar, Harsh; Ossikovski, Razvigor; Vitkin, I Alex; Ghosh, Nirmalya

    2012-10-01

    Development of methodologies for quantification/unique interpretation of the intrinsic polarimetry characteristics of biological tissues are important for various applications involving tissue characterization/diagnosis. A detailed comparative evaluation of the polar decomposition and the differential matrix decomposition of Mueller matrices for extraction/quantification of the intrinsic polarimetry characteristics (with special emphasis on linear retardance δ, optical rotation Ψ and depolarization Δ parameters was performed, because these are the most prominent tissue polarimetry effects) from complex tissue-like turbid media exhibiting simultaneous scattering and polarization effects. The results suggest that for media exhibiting simultaneous linear retardance and optical rotation polarization events, the use of retarder polar decomposition with its associated analysis which assumes sequential occurrence of these effects, results in systematic underestimation of δ and overestimation of Ψ parameters. Analytical relationships between the polarization parameters (δ, Ψ) extracted from both the retarder polar decomposition and the differential matrix decomposition for either simultaneous or sequential occurrence of the linear retardance and optical rotation effects were derived. The self-consistency of both decompositions is validated on experimental Mueller matrices recorded from tissue-simulating phantoms (whose polarization properties are controlled, known a-priori, and exhibited simultaneously) of increasing biological complexity. Additional theoretical validation tests were performed on Monte Carlo-generated Mueller matrices from analogous turbid media exhibiting simultaneous depolarization (Δ), linear retardance (δ) and optical rotation (Ψ) effects. After successful evaluation, the potential advantage of the differential matrix decomposition over the polar decomposition formalism was explored for monitoring of myocardial tissue regeneration following

  11. 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.

  12. Synthesis and characterization of perfluoroalkyl-terminated polymers

    SciTech Connect

    Hunt, M.O. Jr.; Belu, A.M.; Linton, R.W.; DeSimone, J.M.

    1993-12-31

    The focus of the authors` research was the synthesis of heterophase block copolymers composed of fluorinated segments with conventional polymers. This was accomplished in a facile, unique one pot synthesis via termination of a living polymeric carbanion with a perfluorinated chlorosilane. This synthetic methodology has been successful applied to styrenics, dienes, and siloxanes. Excellent control of the molar mass, molar mass distribution, and functionality was verified using conventional characterization technique such as gel premeation chromatography (GPC), NMR, and elemental analysis. The authors have also shown the utility of time-of-flight secondary ion mass spectrometry (TOF-SIMS) for characterization not only of absolute molar masses and molar mass distributions, but also for the determination of the extent of functionalization.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  14. Directed colloidal assembly and characterization of PZT-polymer composites

    NASA Astrophysics Data System (ADS)

    Smay, James Earl

    composites consisting of PZT lattices in a polymer matrix (3-3), a lattice/polymer matrix with PZT faceplates (3-2), or a lattice/polymer matrix with faceplates and encircled by a solid PZT ring (3-1) were formed and their piezoelectric properties were characterized. The PZT:polymer ratio was controlled by the lattice spacing in these thin composites (˜1 mm). Lattice rod intersections formed high permittivity, low compliance PZT pillars that concentrated stress and electric flux, leading to improved hydrostatic figures of merit.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Mechanical properties characterization and modeling of active polymer gels

    NASA Astrophysics Data System (ADS)

    Marra, Steven Paul

    Active polymer gels expand and contract in response to certain environmental stimuli, such as the application of an electric field or a change in the pH level of the surroundings. This ability to achieve large, reversible deformations with no external mechanical loading has generated much interest in the use of these gels as actuators and "artificial muscles." While much work has been done to study the behavior and properties of these gels, little information is available regarding the full constitutive description of the mechanical and actuation properties. This work focuses on developing a means of characterizing the mechanical properties of active polymer gels and describing how these properties evolve as the gel actuates. Poly(vinyl alcohol)-poly(acrylic acid) (PVA-PAA) gel was chosen as the model material for this work because it is relatively simple and safe to both fabricate and actuate. PVA-PAA gels are fabricated on-site using a solvent-casting technique. These gels expand when moved from acidic to basic solutions, and contract when moved from basic to acidic solutions. Citric acid and sodium bicarbonate were used as the testing solutions for this work. The mechanical properties of the gel were characterized by conducting uniaxial and biaxial tests on thin PVA-PAA gel films. A biaxial testing system has been developed which can measure stresses and deformations of these films in a variety of liquid environments. The experimental results on PVA-PAA gels show these materials to be relatively compliant, and slightly viscoelastic and compressible. These gels are also capable of large recoverable deformations in both acidic and basic environments. A thermodynamically consistent finite-elastic constitutive model was developed to describe the mechanical and actuation behaviors of active polymer gels. The mechanical properties of the gel are characterized by a free-energy function, and the model utilizes an evolving internal variable to describe the actuation

  1. 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).

  2. 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.

  3. 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.

  4. 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

  5. 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.

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

    PubMed

    Della Bona, Alvaro; Corazza, Pedro H; Zhang, Yu

    2014-05-01

    To characterize the microstructure and determine some mechanical properties of a polymer-infiltrated ceramic-network (PICN) material (Vita Enamic, Vita Zahnfabrik) available for CAD-CAM systems. 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 (ν) 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 ν and E were measured using an ultrasonic thickness gauge with a combination of a pulse generator and an oscilloscope. Microstructural analyses showed a ceramic- and a polymer-based interpenetrating network. Mean and standard deviation values for the properties evaluated were: KIc=1.09±0.05MPam(1/2), ρ=2.09±0.01g/cm(3), ν=0.23±0.002 and E=37.95±0.34GPa. The PICN material showed mechanical properties between porcelains and resin-based composites, reflecting its microstructural components. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Characterization of electroelastomers based on interpenetrating polymer networks

    NASA Astrophysics Data System (ADS)

    Ha, Soon Mok; Wissler, Michael; Pelrine, Ron; Stanford, Scott; Kovacs, Gabor; Pei, Qibing

    2007-04-01

    Interpenetrating polymer networks (IPN) in which one elastomer network is under high tension balanced by compression of the second network have been shown to exhibit electrically-induced strain up to 300% and promise a number of polymer actuators with substantially enhanced performance and stability. This paper describes the mechanical and thermal properties of the IPN electroelastomer films. The quasi-linear viscoelastic model and Yeoh strain energy potential are used to characterize the viscoelastic response and stress-strain behavior of the IPN films in comparison with 3M VHB films, primary component network in the IPN films. Material parameters were determined from uniaxial stress relaxation experiments. An analysis of the results confirms that the IPN composites have reduced viscoelasticity and fast stress-strain response due to preserved prestrain. Differential scanning calorimetry showed two glass transition temperatures that are slightly shifted from the two component networks, respectively. The two networks in the IPN are considered to be independent of each other. The thermal property is also studied with termogravimetric analysis (TG).

  8. Optical characterization and confocal fluorescence imaging of mechanochromic acrylate polymers

    NASA Astrophysics Data System (ADS)

    van Horn, M.; Smith, P.; Mason, B. P.; Hemmer, J. R.; Read de Alaniz, J.; Hooper, J. P.; Osswald, S.

    2015-01-01

    The development of mechanochromic molecules has opened new pathways for the study of localized stress and failure in polymers. Their application as stress or temperature diagnostics, however, requires suitable measurement techniques capable of detecting the force- and temperature-sensitive chemical species with high spatial resolution. Confocal imaging techniques offer excellent spatial resolution but the energy input during these measurements can itself affect the activation state of the mechanochromic species. Here, we present a systematic study of the effects of laser-based imaging on the activation and fluorescence behavior of mechanochromic spiropyran (SP) integrated into poly(methyl acrylate) (PMA) and poly(methyl methacrylate) matrices using a confocal Raman microspectrometer. Localized stress and temperature activation were studied by means of high-rate compressive loading and dynamic fracture. Laser illumination of SP in PMA revealed a strong excitation wavelength- and power-dependence. Suitable correction functions were established and used to account for the observed laser effects. The presented study demonstrates that confocal imaging using conventional Raman spectrometers is a powerful characterization tool for localized stress analysis in mechanochromic polymers, offering quantifiable information on the activation state with high spatial resolution. However, laser-mechanophore interactions must be well understood and effects of laser excitation and exposure times must be taken into consideration when interpreting the obtained results.

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

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

    PubMed Central

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

    2011-01-01

    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 seconds 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 amu) of the N-terminal thermal decomposition product and a −32 amu 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. PMID:21952765

  7. Mass spectrometry characterization of the thermal decomposition/digestion (TDD) at cysteine in peptides and proteins in the condensed phase.

    PubMed

    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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. Polymer blend microspheres for controlled drug release: the techniques for preparation and characterization: a review article.

    PubMed

    Dasan, K Priya; Rekha, C

    2012-11-01

    The use of polymers and their microspheres in drug delivery is well known for they are being widely used in the field of drug delivery. The polymer entraps a drug which is to be released in a predesigned manner in the body through biodegradation. The blending of polymers is one way of modifying and enhancing the properties of polymer- based products which is also a cost effective procedure rather than developing a new product. The molecular weight of the polymer, the composition of the blend, the sphere porosity and size, and drug distribution are found to be controllable factors on which drug delivery depends. Polymer blends are obtained by allowing two polymers to combine as one material which has the advantage of two or more polymers. Polymer microspheres are small spherical particles with diameters in the micrometer range between 1μm to 1000μm which are manufactured from various natural and synthetic materials. Microspheres are used to administer medication in a rate- controlled manner and sometimes in a targeted manner. This review presents various polymer blend- combinations in different ratios, the different processing techniques adopted and the details of their characterization through examples found in a literature survey. The characterization of the different polymer blends or microspheres showed changes in structure, increase in drug loading, encapsulation efficiency, biocompatibility and low cytotoxicity.

  14. Structural characterization of synthetic polymers using thermal-assisted atmospheric pressure glow discharge mass spectrometry.

    PubMed

    Zhang, Ning; Zhou, Yueming; Zhen, Cheng; Li, Yafeng; Xiong, Caiqiao; Wang, Jiyun; Li, Huayi; Nie, Zongxiu

    2012-11-07

    With the development of material science and the practical needs of the polymer industry, rapid characterization of synthetic polymers using mass spectrometry is of sustainable interest. Herein a new method for characterizing synthetic polymers using thermal-assisted atmospheric pressure glow discharge mass spectrometry (TA-APGD-MS) is established. After illustration of the mechanism of ion formation, typical polymer samples such as polystyrene (PS), polyoxymethylene (POM) and poly (butanediol succinate) (PBS) were directly characterized at the molecular level using TA-APGD-MS. The thermal degradation products of synthetic polymers including monomer units and/or other fragments were rapidly detected by tandem mass spectrometry, providing rich information about the chemical composition for the structural characterization of homo- and co-polymers. The result suggests that TA-APGD-MS allows direct and rapid analysis of both synthetic homo-polymers and co-polymers under ambient conditions without any sample pretreatment. This method features high throughput, high sensitivity and rich information, showing promising applications in polymer science.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Characterization of Conjugated Polymer Actuation under Cerebral Physiological Conditions

    PubMed Central

    Daneshvar, Eugene Dariush; Smela, Elisabeth

    2014-01-01

    Conjugated polymer actuators have potential use in implantable neural interface devices for modulating the position of electrode sites within brain tissue or guiding insertion of neural probes along curved trajectories. The actuation of polypyrrole (PPy) doped with dodecylbenzenesulfonate (DBS) was characterized to ascertain whether it could be employed in the cerebral environment. Microfabricated bilayer beams were electrochemically cycled at either 22 or 37 °C in aqueous NaDBS or in artificial cerebrospinal fluid (aCSF). Nearly all the ions in aCSF were exchanged into the PPy – the cations Na+, K+, Mg2+, Ca2+, as well as the anion PO43−; Cl− was not present. Nevertheless, deflections in aCSF were comparable to those in NaDBS and they were monotonic with oxidation level: strain increased upon reduction, with no reversal of motion despite the mixture of ionic charges and valences being exchanged. Actuation depended on temperature. Upon warming, the cyclic voltammograms showed additional peaks and an increase of 70% in the consumed charge. Bending was, however, much less affected: strain increased somewhat (6-13%) but remained monotonic, and deflections shifted (up to 20%). These results show how the actuation environment must be taken into account, and demonstrate proof of concept for actuated implantable neural interfaces. PMID:24574101

  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. 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.

  3. 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.

  4. Kinetic modeling of the polymer-derived ceramics route: investigation of the thermal decomposition kinetics of poly[B-(methylamino)borazine] precursors into boron nitride.

    PubMed

    Bernard, Samuel; Fiaty, Koffi; Cornu, David; Miele, Philippe; Laurent, Pierre

    2006-05-11

    A complete kinetic modeling of the polymer-derived ceramics (PDCs) route is achieved for the first time through the investigation of the solid-state decomposition of a typical melt-spinnable poly[B-(methylamino)borazine] into boron nitride fibers at various heating rates. Through the use of the Lorentz fitting approach, it is shown that the two-step weight loss associated with the polymer-to-ceramic conversion is governed by a complex interplay of five diffusion-type transport mechanisms that are independent of the applied heating schedule. The application of the Friedman method to dynamic thermogravimetry data yields Ea and ln A values that are seen to increase with the extent of the ceramic conversion from region one (Ea = 38.73 kJ mol(-1)) to region five (Ea = 146.64 kJ mol(-1)). This fact indicates that both the mechanisms within those regions are parallel routes to the formation of the final solid-state material and their complexity increases with the conversion progress. The cross-linking process (first weight loss) of the polymer is governed by three dependent poorly energetic mechanisms. The first weight loss is activated by ammonolysis reactions that provide a modified polymer capable of undergoing condensation reactions in regions two and three to yield a highly cross-linked polymer. A large evolution of methylamine is identified during this process. Mineralization (region four) and ceramization (region five) steps are represented by two highly energetic multistep mechanisms. The mineralization step is associated with a large evolution of methylamine and occurs during the transition between the cross-linking and ceramization processes through the cleavage of the inter-ring B-N bonds. Ceramization represents the end of the polymer-to-ceramic conversion in which the planar consolidation of BN hexagons occurs through complex structural rearrangements of the borazine units (cleavage of the intraring B-N bonds) accompanied with an ammonia evolution. Finally

  5. Characterization and recovery of polymers from mobile phone scrap.

    PubMed

    Kasper, Angela C; Bernardes, Andréa M; Veit, Hugo M

    2011-07-01

    Electronic scrap is part of a universally wide range of obsolete, defective, or used materials that need to be disposed of or recycled in an ecologically friendly manner. The present study focused on the polymers present in mobile phone scrap. In mobile phones, polymers are found in frames and in printed circuit boards (PCBs). The frames are mainly made of polymers whereas PCBs use a variety of material (polymers, ceramics, and metals) which makes recycling more difficult. As a first step, mobile phones were collected, separated by manufacturer/model, and weighed, and the principal polymer types identified. The frames and PCBs were processed separately. The metals in PCBs were separated out by an electrostatic separation process. The resulting polymeric material was identified and mixed with the polymers of frames to fabricate the samples. Two types of samples were made: one with polymeric frames, and the other with a mixture of frames and polymeric fraction from the PCBs. Both kinds of sample were fabricated by injection moulding. The samples were evaluated by mechanical tests (tensile, impact, and hardness) to verify the feasibility of recycling the polymers present in mobile phone scrap. The results demonstrated the technical viability of recovering polymers using mechanical processing followed by an injection process.

  6. 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.

  7. "H"-shape second order NLO polymers: synthesis and characterization.

    PubMed

    Li, Zhong'an; Hu, Pan; Yu, Gui; Zhang, Wei; Jiang, Zuoquan; Liu, Yunqi; Ye, Cheng; Qin, Jingui; Li, Zhen

    2009-02-28

    In this work, two "H"-shape and one "AB"-type second order nonlinear optical (NLO) polymers were prepared for the first time. The linkage positions of chromophores in the "H"-shape polymers were shoulder-to-shoulder, in which the chromophore moieties were part of the polymeric backbone. The subtle structure could be easily modified by the introduction of different isolation groups, to adjust the property of the resultant polymers. All the polymers exhibited good film-forming ability and thermal stability. The second harmonic generation (SHG) experiments demonstrated that the two "H"-shape polymers (P1 and P2) exhibited large SHG coefficients of d(33) values (up to 90 pm V(-1)), and P2 even demonstrated relatively good long-term temporal stability.

  8. 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

  9. 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...

  10. 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...

  11. 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%.

  12. 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.

  13. 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

  14. Design, Synthesis, and Characterization of High Performance Polymer Electrolytes for Printed Electronics and Energy Storage

    DTIC Science & Technology

    2016-03-31

    AFRL-AFOSR-VA-TR-2016-0168 Design, Synthesis, and Characterization of High Performance Polymer Electrolytes for Printed Electronics and Energy ...Sep 2015 4. TITLE AND SUBTITLE Design, Synthesis, and Characterization of High Performance Polymer Electrolytes for Printed Electronics and Energy ... energy storage. This project produced 11 peer reviewed papers and results in the training of 3 graduate students and two postdoctoral fellows. The

  15. 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

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

    USDA-ARS?s Scientific Manuscript database

    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...

  17. 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.

  18. Fabrication and characterization of polymer composites for endodontic use.

    PubMed

    Alhashimi, R; Mannocci, F; Foxton, R; Deb, S

    2014-06-01

    To develop a low-density polyethylene-hydroxyapatite (HA-PE) composite with properties tailored to function as a potential root canal filling material. Hydroxyapatite and polyethylene mixed with strontium oxide as a radiopacifier were extruded from a single screw extruder fitted with an appropriate die to form fibres. The composition of the composite was optimized with clinical handling and placement in the canal being the prime consideration. The fibres were characterized using infrared spectroscopy (FTIR), and their thermal properties determined using differential scanning calorimetry (DSC). The tensile strength and elastic modulus of the composite fibres and gutta-percha were compared, dry and after 1 month storage in simulated body fluid (SBF), using a universal testing machine. The radiopacity of the fibres was determined using digital radiography. The interaction of the composites with eugenol was evaluated and compared with gutta-percha. Data of the tensile test were submitted to two-way anova and Bonferroni tests (P < 0.05). The endothermic peaks obtained from the DSC studies showed that the melting point of the HA/PE composites ranged between 110.5 and 111.2 °C, whereas gutta-percha exhibited a melting point at 52 °C. The tensile strength and elastic modulus of the silanated HA/PE composites were significantly higher than those of gutta-percha (P < 0.0001) under dry conditions and 1 month storage in SBF. The gutta-percha in eugenol showed a significant increase in the polymer molar mass, whereas the silanated HA/PE composites were unchanged. Radiological evaluations demonstrated that silanated HA/PE fibres were sufficiently radiopaque. Promising materials for endodontic applications have been developed, offering relevant benefits over the traditional materials in terms of mechanical and chemical properties. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

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

    SciTech Connect

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

    2016-05-06

    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{sup −4} Scm{sup −1}. The dielectric data were analyzed using Complex impedance Z*, Dielectric loss ε’, Tangent loss for prepared polymer electrolyte membrane with the highest conductivity samples at various temperature.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. 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.

  7. Design and characterization of well-defined supramolecular polymers

    NASA Astrophysics Data System (ADS)

    Schaefer, Kathleen; Kade, Matthew; Hawker, Craig; Kramer, Edward

    2007-03-01

    Polymeric materials with well-defined and controllable temperature dependent properties are of interest both for technological applications and fundamental physical studies. Melt processing requires low viscosity, while resistance to fracture is desirable at material operating temperatures, and these two properties are often mutually exclusive. Through controlled radical polymerization (ATRP) we have synthesized tailor-made polymers with MHB groups specifically located at one or both chain ends or randomly along the backbone to provide thermal tunability, and by changing the nature of the MHB group (complementary or self-complementary) we can control the specificity and type of the polymer-polymer interaction. As a simple model system, we investigate the case of two end-functional MHB homopolymers that form a novel supramolecular diblock copolymer. Two energies are expected to be important in this system---χN, the Flory-Huggins interaction parameter times the degree of polymerization, which describes the polymer-polymer interaction, and ɛ, the binding energy of the MHB group. Using deuterium labeled polymers in various multilayer thin film structures, dynamic secondary ion mass spectrometry (dSIMS) allows each of these parameters to be measured independently and these values used to design technologically and physically interesting new materials.

  8. 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

  9. Syntheses and characterizations of two new energetic copper-amine-DNANT complexes and their effects on thermal decomposition of RDX

    NASA Astrophysics Data System (ADS)

    Qiu, Qianqian; Xu, Kangzhen; Yang, Shihe; Gao, Zhe; Zhang, Hang; Song, Jirong; Zhao, Fengqi

    2013-09-01

    Two novel copper complexes of dinitroacetonitrile (DNANT), Cu(NH3)4(DNANT)2 (1) and Cu(en)2(DNATN)2 (2), have been synthesized for the first time through an unique reaction, and structurally characterized. The single-crystal X-ray structural analysis shows that the Cu2+ cations in the two complexes share a similar four-coordinated structure, which however does not directly involve the main energetic DNANT- anion. The differential scanning calorimetry (DSC) study reveals that the two complexes have higher thermal stability and lower sensitivity than the analogous FOX-7 complexes, and exhibit good catalytic action to the decomposition of RDX.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Characterization of polymer adsorption onto drug nanoparticles using depletion measurements and small-angle neutron scattering.

    PubMed

    Goodwin, Daniel J; Sepassi, Shadi; King, Stephen M; Holland, Simon J; Martini, Luigi G; Lawrence, M Jayne

    2013-11-04

    Production of polymer and/or surfactant-coated crystalline nanoparticles of water-insoluble drugs (nanosuspensions) using wet bead milling is an important formulation approach to improve the bioavailability of said compounds. Despite the fact that there are a number of nanosuspensions on the market, there is still a deficiency in the characterization of these nanoparticles where further understanding may lead to the rational selection of polymer/surfactant. To this end small-angle neutron scattering (SANS) measurements were performed on drug nanoparticles milled in the presence of a range of polymers of varying molecular weight. Isotopic substitution of the aqueous solvent to match the scattering length density of the drug nanoparticles (i.e., the technique of contrast matching) meant that neutron scattering resulted only from the adsorbed polymer layer. The layer thickness and amount of hydroxypropylcellulose adsorbed on nabumetone nanoparticles derived from fitting the SANS data to both model-independent and model dependent volume fraction profiles were insensitive to polymer molecular weight over the range Mv = 47-112 kg/mol, indicating that the adsorbed layer is relatively flat but with tails extending up to approximately 23 nm. The constancy of the absorbed amount is in agreement with the adsorption isotherm determined by measuring polymer depletion from solution in the presence of the nanoparticles. Insensitivity to polymer molecular weight was similarly determined using SANS measurements of nabumetone or halofantrine nanoparticles stabilized with hydroxypropylmethylcellulose or poly(vinylpyrrolidone). Additionally SANS studies revealed the amount adsorbed, and the thickness of the polymer layer was dependent on both the nature of the polymer and drug particle surface. The insensitivity of the adsorbed polymer layer to polymer molecular weight has important implications for the production of nanoparticles, suggesting that lower molecular weight polymers

  15. 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

  16. Synthesis and Characterization of Bioactive Tamoxifen-conjugated Polymers

    PubMed Central

    Rickert, Emily L.; Trebley, Joseph P.; Peterson, Anton C.; Morrell, Melinda M.; Weatherman, Ross V.

    2008-01-01

    Macromolecular conjugates of tamoxifen could perhaps be used to circumvent some of the limitations of the extensively used breast cancer drug. To test the feasibility of these conjugates, a 4-hydroxytamoxifen analog was conjugated to a diaminoalkyl linker and then conjugated to activated esters of a poly(methacrylic acid) polymer synthesized by atom transfer radical polymerization. A polymer conjugated to the 4-hydroxytamoxifen analog with a six carbon linker showed high affinity for both estrogen receptor alpha and estrogen receptor beta and potent antagonism of the estrogen receptor in cell-based transcriptional reporter assays. These results suggest that the conjugation of 4-hydroxytamoxifen to a polymer results in a macromolecular conjugate that can display ligand in a manner that can be recognized by estrogen receptor and still act as a potent antiestrogen in cells. PMID:17929966

  17. Processing, Characterization, and Modeling of Polymer/Clay Nanocomposite Foams

    NASA Astrophysics Data System (ADS)

    Jo, Choonghee; Naguib, Hani E.

    2007-04-01

    The effects of the material parameters and processing conditions on the foam morphologies, and mechanical properties of polymer/clay nanocomposite foams were studied. Microcellular closed-cell nanocomposite foams were manufactured with poly(methylmethacrylate) (PMMA) and high density polyethylene (HDPE), where the nanoclay loadings of 0.5, 1.0, and 2.0 wt% were used. The effect of clay contents and foaming conditions on the volume expansion ratio, cell size, elastic modulus, tensile strength, and elongation at break were investigated and compared between amorphous and semicrystalline polymers. An elastic modulus model for tensile behavior of foams was proposed by using the micromechanics theory. The model was expressed in terms of microstructural properties of polymer and physical properties of the foams. The tensile experimental data of the foams were compared with those predicted by the theoretical model.

  18. 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.

  19. Synthesis of Nanoporous Ni-Co Mixed Oxides by Thermal Decomposition of Metal-Cyanide Coordination Polymers.

    PubMed

    Zakaria, Mohamed B; Hu, Ming; Pramanik, Malay; Li, Cuiling; Tang, Jing; Aldalbahi, Ali; Alshehri, Saad M; Malgras, Victor; Yamauchi, Yusuke

    2015-07-01

    A straightforward strategy to prepare nanoporous metal oxides with well-defined shapes is highly desirable. Through thermal treatment and a proper selection of metal-cyanide coordination polymers, nanoporous nickel-cobalt mixed oxides with different shapes (i.e., flakes and cubes) can be easily prepared. Our nanoporous materials demonstrate high electrocatalytic activity for oxygen evolution reaction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. 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.

  1. 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.

  2. 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.

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

    SciTech Connect

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

    2016-07-06

    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{sup −5} (Ω.cm){sup −1}, with tow of absorption peak at 426,805 nm has been attributed due to quantized size of polyaniline conducting polymer.

  4. Computational Optimization and Characterization of Molecularly Imprinted Polymers

    NASA Astrophysics Data System (ADS)

    Terracina, Jacob J.

    Molecularly imprinted polymers (MIPs) are a class of materials containing sites capable of selectively binding to the imprinted target molecule. Computational chemistry techniques were used to study the effect of different fabrication parameters (the monomer-to-target ratios, pre-polymerization solvent, temperature, and pH) on the formation of the MIP binding sites. Imprinted binding sites were built in silico for the purposes of better characterizing the receptor - ligand interactions. Chiefly, the sites were characterized with respect to their selectivities and the heterogeneity between sites. First, a series of two-step molecular mechanics (MM) and quantum mechanics (QM) computational optimizations of monomer -- target systems was used to determine optimal monomer-to-target ratios for the MIPs. Imidazole- and xanthine-derived target molecules were studied. The investigation included both small-scale models (one-target) and larger scale models (five-targets). The optimal ratios differed between the small and larger scales. For the larger models containing multiple targets, binding-site surface area analysis was used to evaluate the heterogeneity of the sites. The more fully surrounded sites had greater binding energies. Molecular docking was then used to measure the selectivities of the QM-optimized binding sites by comparing the binding energies of the imprinted target to that of a structural analogue. Selectivity was also shown to improve as binding sites become more fully encased by the monomers. For internal sites, docking consistently showed selectivity favoring the molecules that had been imprinted via QM geometry optimizations. The computationally imprinted sites were shown to exhibit size-, shape-, and polarity-based selectivity. This represented a novel approach to investigate the selectivity and heterogeneity of imprinted polymer binding sites, by applying the rapid orientation screening of MM docking to the highly accurate QM-optimized geometries. Next

  5. 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

  6. 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...

  7. 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...

  8. 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.

  9. 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.

  10. 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.

  11. Surface Characterization of Polymer Blends by XPS and ToF-SIMS

    PubMed Central

    Chan, Chi Ming; Weng, Lu-Tao

    2016-01-01

    The surface properties of polymer blends are important for many industrial applications. The physical and chemical properties at the surface of polymer blends can be drastically different from those in the bulk due to the surface segregation of the low surface energy component. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary mass spectrometry (ToF-SIMS) have been widely used to characterize surface and bulk properties. This review provides a brief introduction to the principles of XPS and ToF-SIMS and their application to the study of the surface physical and chemical properties of polymer blends. PMID:28773777

  12. 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.

  13. 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.

  14. 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.

  15. 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)

  16. 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)

  17. Characterization and antimicrobial activity of silver nanoparticles prepared by a thermal decomposition technique

    NASA Astrophysics Data System (ADS)

    Tam, Le Thi; Phan, Vu Ngoc; Lan, Hoang; Thuy, Nguyen Thanh; Hien, Tran Minh; Huy, Tran Quang; Quy, Nguyen Van; Chinh, Huynh Dang; Tung, Le Minh; Tuan, Pham Anh; Lam, Vu Dinh; Le, Anh-Tuan

    2013-11-01

    Recently, there has been an increasing need of efficient synthetic protocols using eco-friendly conditions including low costs and green chemicals for production of metal nanoparticles. In this work, silver nanoparticles (silver NPs) with average particle size about 10 nm were synthesized by using a thermal decomposition technique. Unlike the colloidal chemistry method, the thermal decomposition method developed has advantages such as the high crystallinity, single-reaction synthesis, and easy dispersion ability of the synthesized NPs in organic solvents. In a modified synthesis process, we used sodium oleate as a capping agent to modify the surface of silver NPs because the oleate has a C18 tail with a double bond in the middle, therefore, forming a kink which is to be effective for aggregative stability. Importantly, the as-synthesized silver NPs have demonstrated strong antimicrobial effects against various bacteria and fungi strains. Electron microscopic studies reveal physical insights into the interaction and bactericidal mechanism between the prepared silver NPs and tested bacteria in question. The observed excellent antibacterial and antifungal activity of the silver NPs make them ideal for disinfection and biomedicine applications.

  18. 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.

  19. 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

  20. 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

  1. Reduced-Volume Fracture Toughness Characterization for Transparent Polymers

    DTIC Science & Technology

    2015-03-21

    dependence of (21) is a major contribution of this work. Siegmund and Brocks (2000), Tijssens et al. (2000), Estevez et al. (2000), Gearing and Anand...With the exception of Gearing and Anand (2004) all of these works are limited to two dimensions. Only Siegmund and Brocks (2000) and Anvari et al...Selden, R., 1987. Fracture energy measurements in polycarbonate and pmma. Polymer Testing, 209–222. Siegmund , T., Brocks, W., 2000. A numerical study

  2. Characterization of the potential energy landscape of an antiplasticized polymer.

    PubMed

    Riggleman, Robert A; Douglas, Jack F; de Pablo, Juan J

    2007-07-01

    The nature of the individual transitions on the potential energy landscape (PEL) associated with particle motion are directly examined for model fragile glass-forming polymer melts, and the results are compared to those of an antiplasticized polymer system. In previous work, we established that the addition of antiplasticizer reduces the fragility of glass formation so that the antiplasticized material is a stronger glass former. In the present work, we find that the antiplasticizing molecules reduce the energy barriers for relaxation compared to the pure polymer, implying that the antiplasticized system has smaller barriers to overcome in order to explore its configuration space. We examine the cooperativity of segmental motion in these bulk fluids and find that more extensive stringlike collective motion enables the system to overcome larger potential energy barriers, in qualitative agreement with both the Stillinger-Weber and Adam-Gibbs views of glass formation. Notably, the stringlike collective motion identified by our PEL analysis corresponds to incremental displacements that occur within larger-scale stringlike particle displacement processes associated with PEL metabasin transitions that mediate structural relaxation. These "substrings" nonetheless seem to exhibit changes in relative size with antiplasticization similar to those observed in "superstrings" that arise at elevated temperatures. We also study the effects of confinement on the energy barriers in each system. Film confinement makes the energy barriers substantially smaller in the pure polymer, while it has little effect on the energy barriers in the antiplasticized system. This observation is qualitatively consistent with our previous studies of stringlike motion in these fluids at higher temperatures and with recent experimental measurements by Torkelson and co-workers.

  3. 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 %.

  4. 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.

  5. 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.

  6. 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

  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. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Protamine-sensitive polymer membrane electrode: characterization and bioanalytical applications.

    PubMed

    Yun, J H; Meyerhoff, M E; Yang, V C

    1995-01-01

    A polymeric membrane electrode that exhibits significant and analytically useful potentiometric response to submicromolar levels of the heparin antagonist, protamine, is reported. The sensor is prepared by incorporating a lipophilic cation exchanger, potassium tetrakis(4-chlorophenyl)borate (KTpClPB) (at 1 wt%), within a specially formulated polymer membrane composed of 33 wt% 2-nitrophenyl octyl ether (2-NPOE), and 66 wt% poly(vinyl chloride) (PVC). When the polymer film is mounted in an appropriate electrode body, the resulting membrane electrode responds reproducibly to protamine via a nonequilibrium quasi-steady-state change in the phase boundary potential at the membrane/sample interface. Such response can be used to directly monitor, via classical potentiometric titrations, the binding between protamine and a variety of native (porcine and beef) as well as low-molecular-weight heparins. Scatchard analysis of the EMF titration data provides binding constants and stoichiometries for protamine-heparin interactions. The electrode can be further used to follow the enzymatic digestion of protamine by trypsin. In the presence of a given level of protamine, initial rates of potential decrease (-dE/dt) are shown to be linearly related to trypsin activity in solution over the range of 0-130 units/ml. The speed and simplicity of the protamine sensor make it an attractive alternative to classical methods for studying the interaction of protamine with other biologically important macromolecules as well as the proteolytic activity and reaction kinetics of trypsin.

  17. 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.

  18. 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.

  19. Synthesis and Characterization of Magnetically Controllable Nanostructures Using Different Polymers

    NASA Astrophysics Data System (ADS)

    Turcu, Rodica; Nan, Alexandrina; Craciunescu, Izabell; Leostean, Cristian; Macavei, Sergiu; Taculescu, Alina; Marinica, Oana; Daia, Camelia; Vekas, Ladislau

    2010-12-01

    We report a comparative study of hybrid nanostructures prepared by using water based magnetic nanofluids and polymers such as poly(N-isopropylacrylamide) and pyrrole copolymer functionalized with glycyl-leucine. Design of magnetic nanostructures could be achieved using different synthesis procedures that allow either coating or clustering the magnetic nanoparticles from magnetic fluid by the addition of polymer. Physical-chemical characteristics of hybrid magnetic nanostructures were investigated by FTIR, TEM, DLS, rotational viscosimetry and magnetization measurements. Functionalized pyrrole copolymer coated magnetite nanoparticles with mean size around 9 nm have superparamagnetic behavior and saturation magnetization value of 65 emu/g_Fe3O4. Clusters of magnetite nanoparticles from the water based magnetic nanofluid were encapsulated into polymeric PNIPA spheres having diameters in the range 50-100 nm. The procedure applied allowed to achieve high magnetic loading of polymeric microspheres, having saturation magnetization value of 41 emu/g. Also, the stable suspension in water of thermoresponsive magnetic microgel, as well as the dried samples shows superparamagnetic behavior. It was evidenced that the thermally induced transition from the swollen to collapsed state of magnetic microgels occurs around 30° C.

  20. Synthesis and characterization of long perylenediimide polymer fibers: from bulk to the single-molecule level.

    PubMed

    De Witte, Pieter A J; Hernando, Jordi; Neuteboom, Edda E; van Dijk, Erik M H P; Meskers, Stefan C J; Janssen, René A J; van Hulst, Niek F; Nolte, Roeland J M; García-Parajó, Maria F; Rowan, Alan E

    2006-04-20

    The synthesis and characterization of perylenediimide polyisocyanides is reported. In addition to short oligomers, our synthetic approach results in the formation of extremely long, well-defined, and rigid perylenediimide polymers. Ordering and close-packing of the chromophores in these long polymers is guaranteed by attachment to a polyisocyanide backbone with amino acid side chains. Hydrogen bonding interactions between those groups stabilize and rigidify the helical polymer structure. The rodlike nature of the synthesized long perylenediimide pendant polyisocyanides as well as the helical arrangement of the chromophores is demonstrated by means of atomic force microscopy. Remarkably, polymer fibers up to 1 mum in length have been visualized, containing several thousands of perylenediimide molecules. Circular dichroism spectroscopy reveals the chiral organization of the chromophore units in the polymer, whereas absorption and emission measurements prove the occurrence of excited-state interactions between those moieties due to the close packing of the chromophore groups. However, an intricate optical behavior is encountered in bulk as a result of the coexistence of short oligomers and long polymers of perylenediimide, a situation subsequently uncovered by means of single-molecule experiments. Individual long helical perylenediimide polyisocyanides exhibit a typical red-shifted fluorescence spectrum, which, together with depolarized emission continuously decreasing in time, demonstrate that fluorescence arises from multiple excimer-like species in the polymer. Upon continuous irradiation of these long polymers, a fast decay in fluorescence lifetime is observed, a situation explained by photoinduced creation of quenching sites. Radical/ion formation by intramolecular electron transfer between close-by perylenediimide moieties is the most probable mechanism for this process. Appropriate control of the electron-transfer process might open the possibility of applying

  1. 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

  2. A review of recent trends in polymer characterization using non-destructive vibrational spectroscopic modalities and chemical imaging.

    PubMed

    Mukherjee, Sindhuraj; Gowen, Aoife

    2015-10-01

    This review focuses on the recent developments in vibrational spectroscopy and chemical imaging (i.e. Raman, Near Infrared, Mid Infrared) to characterize polymers in diverse forms, their behaviour and transient phenomenon. First, important polymeric properties and traditional methods of their characterization are outlined. Then relative advantages & disadvantages have been presented of different characterization methods are presented. This is followed by a detailed review of applications of chemical imaging and spectroscopic techniques in polymer characterization, including the limitations encountered. The article ends with a discussion on the future of chemical imaging with regards to polymer characterization. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Using singular value decomposition to characterize protein-protein interactions by in-cell NMR spectroscopy.

    PubMed

    Majumder, Subhabrata; DeMott, Christopher M; Burz, David S; Shekhtman, Alexander

    2014-05-05

    Distinct differences between how model proteins interact in-cell and in vitro suggest that the cytosol might have a profound effect in modulating protein-protein and/or protein-ligand interactions that are not observed in vitro. Analyses of in-cell NMR spectra of target proteins interacting with physiological partners are further complicated by low signal-to-noise ratios, and the long overexpression times used in protein-protein interaction studies may lead to changes in the in-cell spectra over the course of the experiment. To unambiguously resolve the principal binding mode between two interacting species against the dynamic cellular background, we analyzed in-cell spectral data of a target protein over the time course of overexpression of its interacting partner by using single-value decomposition (SVD). SVD differentiates between concentration-dependent and concentration-independent events and identifies the principal binding mode between the two species. The analysis implicates a set of amino acids involved in the specific interaction that differs from previous NMR analyses but is in good agreement with crystallographic data. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Characterization of a cyclic olefin polymer microcentrifuge tube.

    PubMed

    Waxman, Lloyd; Erwin, Rachel L; Vilivalam, Vinod D

    2017-05-01

    Here, we describe the properties of a prototype microcentrifuge tube made from the plastic cyclic olefin polymer (COP). This material has been used in the manufacture of primary containers including syringes and vials for the storage, shipment, and delivery of biotherapeutics, vaccines, and cell therapy products. Its low level of extractable substances and metals along with its glass-like clarity make COP an attractive material for the fabrication of microcentrifuge tubes and other consumable laboratory plasticware where contamination is an important consideration, such as in the storage and analysis of labile proteins, nucleic acids, and metabolites. We compare the performance of microcentrifuge tubes made of COP with that of several brands made of polypropylene (PP), the plastic most widely used in the manufacture of microcentrifuge tubes. Our results show COP microcentrifuge tubes perform as well as tubes made of PP, with reduced levels of compounds capable of leaching into solvents typically used in the laboratory.

  9. 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.

  10. 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.

  11. 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

  12. 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.

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

    PubMed

    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

    2015-12-04

    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 (13)C-graphene is employed to separate the Raman signal G-band between (12)C-a-Cs and (13)C-graphene in the Raman spectrum. The residence of the polymer residues is clearly confirmed by the different Raman signals of two different isotopes ((12)C and (13)C) 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Nanoparticle-polymer composite membranes: Synthesis, characterization, and environmental applications

    NASA Astrophysics Data System (ADS)

    Taurozzi, Julian S.

    Advances in nanotechnology and materials science offer new possibilities for the development of novel water treatment technologies A salient example is the emergence of a new generation of nanostructured membranes with improved separation properties and, in some cases, multifunctional capabilities. The present work explores different aspects of the formation of nanoparticle-enabled membranes, focusing on the dependence between synthetic methods, nanoparticle properties, and the performance of the obtained membranes. The effects of nanoparticle loading, size and morphology, and methods of nanoparticle incorporation on the functional properties of the resulting nanocomposite membranes are studied. Additionally, empirical predictors of membrane performance for the rational design of nanocomposite membranes and novel strategies for the manufacture of membrane-based sensors and biofouling resistant membrane spacers are presented. The first chapter of the dissertation provides an overview of the theory of phase inversion in polymer blends -- one of the main methods for the fabrication of ultrafiltration membranes. The second chapter describes the study of the effect of shape and loading of carbon nanoparticle fillers on the hydraulic properties of nanocomposite membranes. In the third chapter, the effects of casting mixture composition and nanoparticle incorporation route on the morphological structure and separation performance of nanocomposite membranes are described and the potential use of these nanocomposites for the mitigation of membrane biofouling is discussed. Finally, in the last chapter, a method for the synthesis of a nanoparticle-enabled, membrane-based sensor for water quality control is presented.

  2. 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.

  3. End-functionalized polymers. 1. Synthesis and characterization of perfluoroalkyl-terminated polymers via chorosilane derivatives

    SciTech Connect

    Hunt, M.O. Jr; Belu, A.M.; Linton, R.W.; DeSimone, J.M. )

    1993-08-01

    Surface-active, perfluoroalkyl-terminated block copolymers were synthesized and characterized. These heterophase block copolymers were made by terminating a variety of living anionic polymerizations with a chlorosilane derivative containing a perfluoroalkyl group. This synthetic methodology was successfully applied to the anionic polymerization of styrene and 1,3-dienes. Perfluoroalkyl-terminated poly(olefin)s were obtained via hydrogenation of the unsaturated poly(diene) materials. Excellent control of the molar mass, molar mass distribution, and functionality was verified using conventional characterization techniques such as gel permeation chromatography, NMR, and elemental analysis. In addition, time-of-flight secondary ion mass spectrometry (TOF-SIMS) was employed to characterize the absolute molar masses and molar mass distributions and also the extent of functionalization.

  4. 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.

  5. 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.

  6. 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.

  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. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Recent developments in the detailed characterization of polymers by multidimensional chromatography.

    PubMed

    Baumgaertel, Anja; Altuntaş, Esra; Schubert, Ulrich S

    2012-06-01

    Synthetic polymers as well as biopolymers reveal complex structures, such as variations in functionality, chain length and architecture. Therefore, combinations of different chromatographic techniques are a prerequisite for a detailed characterization. One possible approach is the combination of high performance liquid chromatography at critical conditions (LCCC) and size-exclusion chromatography, also named as two-dimensional chromatography, which allows the separation of the polymers according to different properties, like molar mass, chemical composition or functionality. In addition, LCCC hyphenated with different mass spectrometry techniques, e.g. MALDI-TOF or ESI-TOF, leads to additional information about molecular details of the polymeric structure. We summarize in this article the recent developments in two-dimensional chromatography of synthetic polymers and biopolymers since 2005. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. 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.

  17. 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.

  18. 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.

  19. 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.)

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Electrochemical characterization of plasma polymer coatings in corrosion protection of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Chan, Yenfong; Yu, Qingsong

    2005-07-01

    Low-temperature plasma polymerization is a promising pretreatment technique to create environmentally friendly coating systems for corrosion protection of aluminum alloys. In this study, the pretreatment effects of plasma treatment and plasma polymerization on corrosion properties of alclad aluminum alloy 2024-T3 ([2A]) were investigated using electrochemical characterization techniques, including cyclic polarization (CP) and electrochemical impedance spectroscopy (EIS). The [2A] panels were coated with an ultrathin layer (~50 nm) of plasma polymers in a direct current (dc) glow discharge of trimethylsilane or its mixtures with one of two diatomic gases (O2 and N2). The CP measurement results showed that the plasma polymer coated [2A] panels exhibited more negative corrosion potentials (Ecorr), smaller corrosion currents (Icorr), and no surface passivation when compared with uncoated [2A] control panels. The lower values of Icorr imply a higher corrosion resistance on the plasma polymer coated [2A]. When investigated using EIS, these plasma polymer coated [2A] panels exhibited higher impedance (|Z|) at lower frequency when first immersed in electrolyte solution, yet degraded quickly to a similar level as uncoated controls within 1 day of immersion. These results illustrated that thin plasma polymer films provided a certain but very limited corrosion resistance to [2A] substrate; their dominant role in plasma interface engineered coating systems still relied mostly on their adhesion enhancement at metal/paint interface as observed in our previous studies.

  5. Preparation and characterization of novel PBAE/PLGA polymer blend microparticles for DNA vaccine delivery.

    PubMed

    Balashanmugam, Meenashi Vanathi; Nagarethinam, Sivagurunathan; Jagani, Hitesh; Josyula, Venkata Rao; Alrohaimi, Abdulmohsen; Udupa, Nayanabhirama

    2014-01-01

    Poly(beta-amino ester) (PBAE) with its pH sensitiveness and Poly(lactic-co-glycolic acid) (PLGA) with huge DNA cargo capacity in combination prove to be highly efficient as DNA delivery system. To study the effectiveness of novel synthesized PBAE polymer with PLGA blend at different ratios in DNA vaccine delivery. In the present study, multifunctional polymer blend microparticles using a combination of PLGA and novel PBAE polymers A1 (bis(3-(propionyloxy)propyl)3,3'-(propane-1,3-diyl-bis(methylazanediyl))dipropanoate) and A2 (bis(4-(propionyloxy)butyl)3,3'-(ethane-1,2-diyl-bis(isopropylazanediyl))dipropanoate) at different ratios (85:15, 75:25, and 50:50) were prepared by double emulsion solvent removal method. The microparticles were characterized for cytotoxicity, transfection efficiency, and DNA encapsulation efficiency. It was evident from results that among the microparticles prepared with PLGA/PBAE blend the PLGA:PBAE at 85:15 ratio was found to be more effective combination than the microparticles prepared with PLGA alone in terms of transfection efficiency and better DNA integrity. Microparticles made of PLGA and PBAE A1 at 85:15 ratio, respectively, were found to be less toxic when compared with microparticles prepared with A2 polymer. The results encourage the use of the synthesized PBAE polymer in combination with PLGA as an effective gene delivery system.

  6. 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.

  7. 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.

  8. Physical characterization of polymer electrolytes as novel iontophoretic drug delivery devices.

    PubMed

    Sahota, T S; Latham, R J; Linford, R G; Taylor, P M

    1999-03-01

    Polymer electrolytes are solid-like materials formed by dispersing a salt at the molecular level in a high molecular weight polymer such as poly(ethylene oxide) (PEO). They have been extensively studied for use in electrochemical applications such as batteries and display devices. This paper considers a novel application of polymer electrolytes as the basis of iontophoretic drug delivery systems. Polymer electrolyte films were cast from solutions of PEO and various drug salts using either water or an acetonitrile/ethanol mixture as the solvent. These films were characterized by variable-temperature polarizing microscopy (VTPM), differential scanning calorimetry (DSC), and alternating current (AC) impedance analysis. The films were around 100-micron thick and mechanically strong; the optical and thermal methods provided evidence that the polymer electrolytes had crystalline and amorphous phases, although some drugs may exist in films as nanodispersions. The amorphous phase is important as ions have greater mobility in this phase and therefore allow a current to be passed when the material is incorporated into a device such as one suitable for drug delivery by iontophoresis. The AC impedance analysis showed that the conductivity of the films varied between 10(-6) and 10(-3) S cm-1, depending on the salt, casting solvent, and temperature. Two drugs in particular were shown to be promising candidates in these systems: lidocaine hydrochloride and lithium chloride.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. Novelmetal-organic photocatalysts: Synthesis, characterization and decomposition of organic dyes

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Nanoscale Mechanical Characterization of Graphene/Polymer Nanocomposites using Atomic Force Microscopy

    NASA Astrophysics Data System (ADS)

    Cai, Minzhen

    Graphene materials, exhibiting outstanding mechanical properties, are excellent candidates as reinforcement in high-performance polymer nanocomposites. In this dissertation, advanced atomic force microscopy (AFM) techniques are applied to study the nanomechanics of graphene/polymer nanocomposites, specifically the graphene/polymer interfacial strength and the stress transfer at the interface. Two novel methods to directly characterize the interfacial strength between individual graphene sheets and polymers using AFM are presented and applied to a series of polymers and graphene sheets. The interfacial strength of graphene/polymer varies greatly for different combinations. The strongest interaction is found between graphene oxide (GO) and polyvinyl alcohol (PVA), a strongly polar, water-based polymer. On the other hand, polystyrene, a non polar polymer, has the weakest interaction with GO. The interfacial bond strength is attributed to hydrogen bonding and physical adsorption. Further, the stress transfer in GO/PVA nanocomposites is studied quantitatively by monitoring the strain in individual GO sheet inside the polymer via AFM and Raman spectroscopy. For the first time, the strains of individual GO sheets in nanocomposites are imaged and quantified as a function of the applied external strains. The matrix strain is directly transferred to GO sheets for strains up to 8%. At higher strain levels, the onset of the nanocomposite failure and a stick-slip behavior is observed. This study reveals that GO is superior to pure graphene as reinforcement in nanocomposites. These results also imply the potential to make a new generation of nanocomposites with exceptional high strength and toughness. In the second part of this dissertation, AFM is used to study the structure of silk proteins and the morphology of spider silks. For the first time, shear-induced self-assembly of native silk fibroin is observed. The morphology of the Brown Recluse spider silk is investigated and a

  19. 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.

  20. 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.

  1. Development of CdS Nanostructures by Thermal Decomposition of Aminocaproic Acid-Mixed Cd-Thiourea Complex Precursor: Structural, Optical and Photocatalytic Characterization.

    PubMed

    Patel, Jayesh D; Mighri, Frej; Ajji, Abdellah; Chaudhuri, Tapas K

    2015-04-01

    The present work deals with two different CdS nanostructures produced via hydrothermal and solvothermal decompositions of aminocaproic acid (ACA)-mixed Cd-thiourea complex precursor at 175 °C. Both nanostructures were extensively characterized for their structural, morphological and optical properties. The powder X-ray diffraction characterization showed that the two CdS nanostructures present a wurtzite morphology. Scanning electron microscopy and energy-dispersive X-ray characterizations revealed that the hydrothermal decomposition produced well-shaped CdS flowers composed of six dendritic petals, and the solvothermal decomposition produced CdS microspheres with close stoichiometric chemical composition. The UV-vis absorption and photoluminescence spectra of CdS dendritic flowers and microsphere nanostructures showed that both nanostructures present a broad absorption between 200 and 700 nm and exhibit strong green emissions at 576 and 520 nm upon excitations at 290 nm and 260 nm, respectively. The transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) characterizations confirmed that CdS microspheres were mesoporous and were composed of small nanocrystals. A possible growth mechanism in the formation of the CdS nanostructures was proposed based on morphology evolution as a function of the reaction time. Furthermore, the as-synthesized CdS nanostructures were found to exhibit highly efficient photocatalytic activities for the degradation of methyl orange (MeO) and rhodamine B (RhB) dyes.

  2. 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

  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. 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. Copyright © 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  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. Green synthesis and characterization of polymer-stabilized silver nanoparticles.

    PubMed

    Medina-Ramirez, Iliana; Bashir, Sajid; Luo, Zhiping; Liu, Jingbo Louise

    2009-10-15

    Silver nanoparticles (Ag-NPs) were synthesized using a facile green chemistry synthetic route. The reaction occurred at ambient temperature with four reducing agents introduced to obtain nanoscale Ag-NPs. The variables of the green synthetic route, such as acidity, concentration of starting materials, and molar ratio of reactants were optimized. Dispersing agents were employed to prevent Ag-NPs from aggregating. Advanced instrumentation techniques, such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (UV-vis), and phase analysis light scattering technique (ZetaPALS) were applied to characterize the morphology, particle size distribution, elemental composition, and electrokinetic behavior of the Ag-NPs. UV-vis spectra detected the characteristic plasmon at approximately 395-410 nm; and XRD results were indicative of face-centered cubic phase structure of Ag. These particles were found to be monodispersed and highly crystalline, displaying near-spherical appearance, with average particle size of 10.2 nm using citrate or 13.7 nm using ascorbic acid as reductants from particle size analysis by ZetaPALS, respectively. The rapid electrokinetic behavior of the Ag was evaluated using zetapotential (from -40 to -42 mV), which was highly dependant on nanoparticle acidity and particle size. The current research opens a new avenue for the green fabrication of nanomaterials (including variables optimization and aggregation prevention), and functionalization in the field of nanocatalysis, disinfection, and electronics.

  7. Characterization of semicrystalline polymers after nanoimprint by spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Wang, Si; Rond, Johannes; Steinberg, Christian; Papenheim, Marc; Scheer, Hella-Christin

    2016-02-01

    Semicrystalline Reg-P3HT (regio-regular poly-3-hexylthiophene) is a promising material for organic electronics. It features relatively high charge mobility and enables easy preparation because of its solubility. Due to its high optical and electrical anisotropy, the size, number and orientation of the ordered domains are important for applications. To control these properties without limitation from crystalline domains existing after spin coating, thermal nanoimprint is performed beyond the melting point. The state of the art of measurement to analyze the complex morphology is X-ray diffraction (XRD). We address an alternative measurement method to characterize the material by its optical properties, spectroscopic ellipsometry. It provides information on the degree of order from the typical fingerprint absorption spectrum. In addition, when the material is modeled as a uniaxial layer, an anisotropy factor can be derived. The results obtained from spectroscopic ellipsometry are in accordance with those from XRD. In particular, spectroscopic ellipsometry is able to distinguish between order along the backbone and order in π- π stacking direction, which is important with respect to conductivity.

  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 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.

  10. 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.

  11. Characterization of Polymer Phase Separation of Reacting Systems

    NASA Astrophysics Data System (ADS)

    Yontz, D. J.; Hsu, S. L.; Gier, D.; Lidy, W.; Mazor, M.

    1997-03-01

    The degree of phase separation and size of the hard domains and soft domains that form in polyurethanes are highly dependent on the temperature at which phase separation occurs. This current study has focused on a polyurea urethane synthesized from toluene diisocyanate (TDI), water, and PPO. The temperature of this very exothermic system increases from room temperature to well over 100 ^circC in less than two minutes. This rise in temperature, especially during the first several minutes in which molecular weight buildup and phase separation compete, plays a significant role in the development of the final phase separated morphology. Samples prepared isothermally displayed a morphology that differed from that of the samples prepared with the inherent temperature profile. The evidence has shown that the phase separation process of this system cannot be predicted easily. Our experimental data have shown that competition between the rate of reaction and the phase separation rate is crucial to the production of this heterogeneous morphology. Infrared spectroscopy and atomic force microscopy analyses have proved to be instrumental in the characterization of the structures produced.

  12. 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.

  13. 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.

  14. 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.

  15. Fabrication and characterization of polymer gel for MRI phantom with embedded lesion particles

    NASA Astrophysics Data System (ADS)

    In, Eunji; Naguib, Hani E.; Haider, Masoom

    2012-04-01

    Magnetic Resonance Imaging (MRI) is a medical imaging technique used in radiology to visualize the detailed internal structure and body soft tissues in complete 3D image. MRI performs best when optimal imaging parameters such as contrast, signal to noise ratio (SNR), spatial resolution and total scan time are utilized. However, due to a variety of imaging parameters that differ with the manufacturer, a calibration medium that allows the control of these parameters is necessary. Therefore, a phantom that behaves similar to human soft tissue is developed to replace a real human. Polymer gel is novel material that has great potential in the medical imaging. Since very few have focused on examining the behavior of polymer lesions, the motivation of this study is to develop a polymer gel phantom, especially for liver, with embedded lesions. Both the phantom and lesions should be capable of reflecting T1 and T2 relaxation values through various characterization processes. In this paper, phantom and lesion particles were fabricated with carrageenan as a gelling agent by physical aggregation. Agar was used as supplementary gelling agent and T2 modifier and Gd-DTPA as T1 modifier. The polymer gel samples were fabricated by varying the concentrations of the gelling agent, and T1 and T2 modifiers. The lesion particles were obtained by extracting molten polymer gel solution in chilled oil bath to obtain spherical shape. The polymer gel properties including density, elastic modulus, dielectric constant and optical properties were measured to compare with human tissue values for long period of time.

  16. 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

  17. 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.

  18. [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.

  19. 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

  20. 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

  1. 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.

  2. Ampicillin-ester bonded branched polymers: characterization, cyto-, genotoxicity and controlled drug-release behaviour.

    PubMed

    Oledzka, Ewa; Sobczak, Marcin; Nalecz-Jawecki, Grzegorz; Skrzypczak, Agata; Kolodziejski, Waclaw

    2014-06-06

    The development and characterization of novel macromolecular conjugates of ampicillin using branched biodegradable polymers has been described in this study. The conjugates have been prepared coupling the β-lactam antibiotic with branched polymer matrices based on the natural oligopeptide core. The cyto- and genotoxicity of the synthesized polymers were evaluated with a bacterial luminescence test, two protozoan assays and Salmonella typhimurium TA1535. The presence of a newly formed covalent bond between the drug and the polymer matrices was confirmed by 1H-NMR and FTIR studies. A drug content (15.6 and 10.2 mole %) in the macromolecular conjugates has been determined. The obtained macromolecular products have been subjected to further in vitro release studies. The total percentage of ampicillin released after 21 days of incubation was nearly 60% and 14% and this resulted from the different physicochemical properties of the polymeric matrices. This is the first report on the application of branched biodegradable polymeric matrices for the covalent conjugation of ampicillin. The obtained results showed that the synthesized macromolecular drug-conjugates might slowly release the active drug molecule and improve the pharmacokinetics of ampicillin.

  3. 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.

  4. 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.

  5. 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

    2017-05-01

    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.

  6. 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.

  7. Preparation, characterization and efficacy evaluation of synthetic biocompatible polymers linking natural antioxidants.

    PubMed

    Trombino, Sonia; Cassano, Roberta; Ferrarelli, Teresa; Leta, Sonia; Puoci, Francesco; Picci, Nevio

    2012-10-26

    The purpose of this work was the synthesis, characterization and efficacy evaluation of new biocompatible antioxidant polymers linking trans-ferulic acid or a-lipoic acid. In particular, ferulic or lipoic acid were introduced in the preformed polymeric backbone. The new antioxidant biopolymers were characterized by Fourier transform infrared spectroscopy and gel permeation chromatography. The degree of functionalization (moles of antioxidant per gram of polymer) was determined by the Gaur-Gupta method for free amino group determination and by the Folin method for the phenolic groups. Their ability to inhibit lipid peroxidation were estimated in rat liver microsomal membranes induced in vitro by tert-BOOH (tert-butyl hydroperoxide), as a source of free radicals. The DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging effect was also evaluated. The obtained systems, with different solubility, showed strong antioxidant and antiradical activities, suggesting potential use as packaging materials for foods, cosmetics, pharmaceuticals and personal care products. Moreover, the cytotoxicity of the synthesized polymers was also evaluated on Caco-2 cell cultures in order to verify their biocompatibility when exposed to an absorptive epithelial cell line.

  8. 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.

  9. Preparation and Characterization of Novel PBAE/PLGA Polymer Blend Microparticles for DNA Vaccine Delivery

    PubMed Central

    Balashanmugam, Meenashi Vanathi; Nagarethinam, Sivagurunathan; Jagani, Hitesh; Josyula, Venkata Rao; Alrohaimi, Abdulmohsen; Udupa, Nayanabhirama

    2014-01-01

    Context. Poly(beta-amino ester) (PBAE) with its pH sensitiveness and Poly(lactic-co-glycolic acid) (PLGA) with huge DNA cargo capacity in combination prove to be highly efficient as DNA delivery system. Objective. To study the effectiveness of novel synthesized PBAE polymer with PLGA blend at different ratios in DNA vaccine delivery. Methods. In the present study, multifunctional polymer blend microparticles using a combination of PLGA and novel PBAE polymers A1 (bis(3-(propionyloxy)propyl)3,3′-(propane-1,3-diyl-bis(methylazanediyl))dipropanoate) and A2 (bis(4-(propionyloxy)butyl)3,3′-(ethane-1,2-diyl-bis(isopropylazanediyl))dipropanoate) at different ratios (85 : 15, 75 : 25, and 50 : 50) were prepared by double emulsion solvent removal method. The microparticles were characterized for cytotoxicity, transfection efficiency, and DNA encapsulation efficiency. Result. It was evident from results that among the microparticles prepared with PLGA/PBAE blend the PLGA : PBAE at 85 : 15 ratio was found to be more effective combination than the microparticles prepared with PLGA alone in terms of transfection efficiency and better DNA integrity. Microparticles made of PLGA and PBAE A1 at 85 : 15 ratio, respectively, were found to be less toxic when compared with microparticles prepared with A2 polymer. Conclusion. The results encourage the use of the synthesized PBAE polymer in combination with PLGA as an effective gene delivery system. PMID:25401137

  10. 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

  11. Production and characterization of polymer microspheres containing trace explosives using precision particle fabrication technology.

    PubMed

    Staymates, Matthew; Fletcher, Robert; Staymates, Jessica; Gillen, Greg; Berkland, Cory

    2010-01-01

    Well characterized test materials are essential for validating the performance of current trace explosive detection systems. These test materials must replicate trace explosive contamination in the form of small particles with characteristic diameters in the micrometer range. In this work, Precision Particle Fabrication was used to fabricate monodisperse polymer microspheres that contain high explosives. Three high explosives were successfully incorporated into the microspheres. Ion mobility spectrometry confirmed that the encapsulation efficiency was typically greater than 50%, with some suspected loss to the aqueous phase during production. This study demonstrates that, with this technique, polymer microspheres containing explosives can be produced with sufficient encapsulation, along with tightly controlled particle size distributions at high production rates. These microspheres have proven to be a valuable test material for trace explosive detectors because of their highly precise size, shape and explosive composition.

  12. 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).

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Fluctuation-conductivity Characterization of Superconducting Bi2Sr2CaCu2O8+d Thin Films Prepared by the Metal-organic Decomposition Method

    NASA Astrophysics Data System (ADS)

    Deguchi, Y.; Kikuchi, H.; Mori, N.; Yamada, Y.; Atsumi, T.; Yoshida, K.; Ishibashi, T.

    We report on the preparation and characterization of Bi2Sr2CaCu2O8+d (Bi2212) thin films. These films on SrTiO3 substrates were fabricated by the metal-organic decomposition method and annealing at a temperature between 810~850 °C. On the basis of the analysis for the fluctuation conductivity σ' above Tc, we characterize properties of Bi2212 films by taking account of overall theoretical σ' terms and momentum cutoff effects. In the analysis we estimate, as a function of Tc, the fluctuation parameters, among which anisotropy and depairing parameters are found to be correlated with Tc.

  18. 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.

  19. 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.

  20. In-line characterization of nanostructured mass-produced polymer components using scatterometry

    NASA Astrophysics Data System (ADS)

    Skovlund Madsen, Jonas; Højlund Thamdrup, Lasse; Czolkos, Ilja; Hansen, Poul Erik; Johansson, Alicia; Garnaes, Jørgen; Nygård, Jesper; Hannibal Madsen, Morten

    2017-08-01

    Scatterometry is used as an in-line metrology solution for injection molded nanostructures to evaluate the pattern replication fidelity. The method is used to give direct feedback to an operator when testing new molding parameters and for continuous quality control. A compact scatterometer has been built and tested at a fabrication facility. The scatterometry measurements, including data analysis and handling of the samples, are much faster than the injection molding cycle time, and thus, characterization does not slow down the production rate. Fabrication and characterization of 160 plastic parts with line gratings are presented here, and the optimal molding temperatures for replication of nanostructures are found for two polymers. Scatterometry results are compared to state of the art metrology solutions: atomic force and scanning electron microscopy. It is demonstrated that the scatterometer can determine the structural parameters of the samples with an accuracy of a few nanometers in less than a second, thereby enabling in-line characterization.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. Synthesis and spectroscopic characterization of a new (aryl-SCN)n polymer: Polythiocyanatohydroquinone

    NASA Astrophysics Data System (ADS)

    Baryshnikov, Gleb V.; Galagan, Rostislav L.; Shepetun, Ludmila P.; Litvin, Valentina A.; Minaev, Boris F.

    2015-09-01

    In the present work we have demonstrated the first synthesis of the polythiocyanogen-like (aryl-SCN)n compound (polythiocyanatohydroquinone) from the initial 1,4-benzoquinone and NH4SCN reagents under the normal conditions in the glacial acetic acid medium. The synthesized amorphous polymer was characterized experimentally by the FT-IR and UV-vis spectroscopic methods accompanied with theoretical assignments by the density functional theory (DFT) and time-dependent DFT calculations. The transmission electron microscopy and the XRD pattern analysis were used to indicate the amorphous structure of the synthesized polymer. The DFT geometry optimization of a number of oligomers (n = 4-8) permit us to predict the possible structure of polythiocyanatohydroquinone and to assign the observed bands in IR and UV-vis absorption spectra. It was found that the synthesized polythiocyanatohydroquinone powder has a complicated structure which can be represented as a branched polymer constructed from the mono- and doubly-SCN-substituted benzene-1,4-diol moieties. This new material demonstrates a good stabilizing effect in respect to colloidal solutions of Ag and Au nanoparticles. Additionally, polythiocyanatohydroquinone is predicted to be a promising candidate for creation of metal-containing composite materials. Its application as a framework for the Pt electrode closing is found very useful.

  8. 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.

  9. 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.

  10. Synthesis and characterization of polymer-protected rhodium and palladium sols in mixed media.

    PubMed

    Jaine, Jacob E; Mucalo, Michael R

    2012-06-01

    A series of polymer-protected rhodium and palladium sols were generated in mixed (organic/aqueous) dispersion media. Protecting polymers used were PAA, PVP, PVA and an oligosaccharide-based protecting agent, arabinogalactan. This is the first systematic study of colloids generated in mixed solvent dispersion media with these protecting agents. The sols were characterized by TEM, UV/Vis spectrophotometry and Photon Correlation Spectroscopy (PCS). In general, the macroscopic stability of the sols depended on the protecting agent/organic cosolvent combination used, with a nonlinear dependence on cosolvent concentration. Observed sol stabilities correlated well with pre-existing hydrodynamic data for the protective polymers, e.g. radius of gyration data. Average particle size and polydispersity of all sols examined decreased as cosolvent concentration increased, with actual cosolvent concentration, protecting agent and reducing agent used influencing the extent of decrease. Sol particle sizes ranged from 0.8 nm to 6.0 nm with sol turbidities decreasing in parallel with the particle sizes. Hydrodynamic sizes (from PCS) tended to reflect the sols' macroscopic stabilities. FTIR studies using adsorbed CO as a spectroscopic surface probe indicated decreases in the ν(CO)(ads) stretching frequency with an increase in cosolvent concentration due to competitive adsorption of CO with the cosolvent molecules on the metal colloid surfaces. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. On the mechanical characterization and modeling of polymer gel brain substitute under dynamic rotational loading.

    PubMed

    Fontenier, B; Hault-Dubrulle, A; Drazetic, P; Fontaine, C; Naceur, H

    2016-10-01

    The use of highly sensitive soft materials has become increasingly apparent in the last few years in numerous industrial fields, due to their viscous and damping nature. Unfortunately these materials remain difficult to characterize using conventional techniques, mainly because of the very low internal forces supported by these materials especially under high strain-rates of deformation. The aim of this work is to investigate the dynamic response of a polymer gel brain analog material under specific rotational-impact experiments. The selected polymer gel commercially known as Sylgard 527 has been studied using a specific procedure for its experimental characterization and numerical modeling. At first an indentation experiment was conducted at several loading rates to study the strain rate sensitivity of the Sylgard 527 gel. During the unloading several relaxation tests were performed after indentation, to assess the viscous behavior of the material. A specific numerical procedure based on moving least square approximation and response surface method was then performed to determine adequate robust material parameters of the Sylgard 527 gel. A sensitivity analysis was assessed to confirm the robustness of the obtained material parameters. For the validation of the obtained material model, a second experiment was conducted using a dynamic rotational loading apparatus. It consists of a metallic cylindrical cup filled with the polymer gel and subjected to an eccentric transient rotational impact. Complete kinematics of the cup and the large strains induced in the Sylgard 527 gel, have been recorded at several patterns by means of optical measurement. The whole apparatus was modeled by the Finite Element Method using explicit dynamic time integration available within Ls-dyna(®) software. Comparison between the physical and the numerical models of the Sylgard 527 gel behavior under rotational choc shows excellent agreements. Copyright © 2016 Elsevier Ltd. All rights

  18. 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.

  19. 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.

  20. 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.

  1. 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).

  2. 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.

  3. Preparation and characterization of shape memory polymer scaffolds via solvent casting/particulate leaching.

    PubMed

    De Nardo, Luigi; Bertoldi, Serena; Cigada, Alberto; Tanzi, Maria Cristina; Haugen, Håvard Jostein; Farè, Silvia

    2012-09-27

    Porous Shape Memory Polymers (SMPs) are ideal candidates for the fabrication of defect fillers, able to support tissue regeneration via minimally invasive approaches. In this regard, control of pore size, shape and interconnection is required to achieve adequate nutrient transport and cell ingrowth. Here, we assessed the feasibility of the preparation of SMP porous structures and characterized their chemico-physical properties and in vitro cell response. SMP scaffolds were obtained via solvent casting/particulate leaching of gelatin microspheres, prepared via oil/water emulsion. A solution of commercial polyether-urethane (MM-4520, Mitsubishi Heavy Industries) was cast on compacted microspheres and leached-off after polymer solvent evaporation. The obtained structures were characterized in terms of morphology (SEM and micro-CT), thermo-mechanical properties (DMTA), shape recovery behavior in compression mode, and in vitro cytocompatibility (MG63 Osteoblast-like cell line). The fabrication process enabled easy control of scaffold morphology, pore size, and pore shape by varying the gelatin microsphere morphology. Homogeneous spherical and interconnected pores have been achieved together with the preservation of shape memory ability, with recovery rate up to 90%. Regardless of pore dimensions, MG63 cells were observed adhering and spreading onto the inner surface of the scaffolds obtained for up to seven days of static in vitro tests. A new class of SMP porous structures has been obtained and tested in vitro: according to these preliminary results reported, SMP scaffolds can be further exploited in the design of a new class of implantable devices.

  4. 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.

  5. 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.

  6. 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

    2017-03-01

    Several polymer films for improved optical properties in optoelectronic devices are presented. In such 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 optoelectronic components, such as organic light-emitting diodes. Three different epoxy acrylate mixtures containing Syntholux 291 EA, bisphenol A glycerolate dimethacrylate, and Sartomer SR 348 L are characterized and optimized with different additives. The adjustable refractive index of the material is achieved by chemical doping using 9-vinylcarbazole. Titanium nanoparticles in the mixtures generate light scattering and increase the refractive index additionally. A high-power stirrer 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, therefore, the viscosity measurement results are presented. After the mixing, the monomer mixture is applied on glass substrates by screen printing. To initiate polymerization, the produced films are irradiated for 10 min with ultraviolet radiation and heat. Transmission measurements of the polymer matrix and roughness measurements complement the characterization.

  7. Electrochemically deposited conducting polymers for reliable biomedical interfacing materials: Formulation, mechanical characterization, and failure analysis

    NASA Astrophysics Data System (ADS)

    Qu, Jing

    Conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) are of interest for a variety of applications including interfaces between electronic biomedical devices and living tissue. These polymers provide an improved interface compared to metal and semiconducting electrodes because of their ionic conductivity, relatively lower stiffness, and ability to incorporate biological molecules. Even though the signal transfer and biocompatibility of conjugated polymers are superior compared as the biointerfacing materials, the durability has been the weakest part for the long-term applications. Even though some efforts have been made to improve the durability of conjugated polymers, little quantitative information of the improved cohesion, adhesion and durability has been reported. In this thesis, the methods of improving the durability of conjugated polymer films, especially PEDOT, were investigated, including alternating the processing methods and components in synthesis. The 7-month in vivo testing showed that the durability of PEDOT films still needed to be improved. As a coating for biosignal transfer, the cohesion, adhesion and electrochemical stability of PEDOT are vital to determine the long-term performance. Not much information hd been developed around the cohesion and adhesion. A thin film cracking method was developed to measure the stiffness, strength and the interfacial shear strength (adhesion) of electrochemically deposited PEDOT. 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 effectiveness of crosslinker and adhesion promoter was demonstrated by this method. It was shown that 5 mole% addition 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%). With the modification of EDOT-acid to the surface of stainless steel

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. Functionalization and characterization of pyrolyzed polymer based carbon microstructures for bionanoelectronics platforms

    NASA Astrophysics Data System (ADS)

    Hirabayashi, Mieko; Mehta, Beejal; Vahidi, Nasim W.; Khosla, Ajit; Kassegne, Sam

    2013-11-01

    In this study, the investigation of surface-treatment of chemically inert graphitic carbon microelectrodes (derived from pyrolyzed photoresist polymer) for improving their attachment chemistry with DNA molecular wires and ropes as part of a bionanoelectronics platform is reported. Polymer microelectrodes were fabricated on a silicon wafer using standard negative lithography procedures with negative-tone photoresist. These microelectrode structures were then pyrolyzed and converted to a form of conductive carbon that is referred to as PP (pyrolyzed polymer) carbon throughout this paper. Functionalization of the resulting pyrolyzed structures was done using nitric, sulfuric, 4-amino benzoic acids (4-ABA), and oxygen plasma etching and the surface modifications confirmed with Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and electron dispersion x-ray spectroscopy (EDS). Post surface-treatment analysis of microelectrodes with FTIR and Raman spectroscopy showed signature peaks characteristics of carboxyl functional groups while EDS showed an increase in oxygen content in the surface-treatment procedures (except 4-ABA) indicating an increase in carboxyl functional group. These functional groups form the basis for peptide bond with aminated oligonucleotides that in turn could be used as molecular wires and interconnects in a bionanoelectronics platform. Post-pyrolysis analysis using EDS showed relatively higher oxygen concentrations at the edges and location of defects compared to other locations on these microelectrodes. In addition, electrochemical impedance measurements showed metal-like behavior of PP carbon with high conductivity (|Z| <1 KΩ) and no detectable detrimental effect of oxygen plasma surface-treatment on electrical characteristic. In general, characterization results—taken together—indicated that oxygen plasma surface-treatment produced more reliable, less damaging, and consistently repeatable generation of carboxyl functional

  13. Experimental and theoretical characterization of implantable neural microelectrodes modified with conducting polymer nanotubes.

    PubMed

    Abidian, Mohammad Reza; Martin, David C

    2008-03-01

    Neural prostheses transduce bioelectric signals to electronic signals at the interface between neural tissue and neural microelectrodes. A low impedance electrode-tissue interface is important for the quality of signal during recording as well as quantity of applied charge density during stimulation. However, neural microelectrode sites exhibit high impedance because of their small geometric surface area. Here we analyze nanostructured-conducting polymers that can be used to significantly decrease the impedance of microelectrode typically by about two orders of magnitude and increase the charge transfer capacity of microelectrodes by three orders of magnitude. In this study poly(pyrrole) (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) nanotubes were electrochemically polymerized on the surface of neural microelectrode sites (1250 microm(2)). An equivalent circuit model comprising a coating capacitance in parallel with a pore resistance and interface impedance in series was developed and fitted to experimental results to characterize the physical and electrical properties of the interface. To confirm that the fitting parameters correlate with physical quantities of interface, theoretical equations were used to calculate the parameter values thereby validating the proposed model. Finally, an apparent diffusion coefficient was calculated for PPy film (29.2+/-1.1 x 10(-6) cm(2)/s), PPy nanotubes (PPy NTs) (72.4+/-3.3 x 10(-6) cm(2)/s), PEDOT film (7.4+/-2.1 x 10(-6) cm(2)/s), and PEDOT nanotubes (PEDOT NTs) (13.0+/-1.8 x 10(-6) cm(2)/s). The apparent diffusion coefficient of conducting polymer nanotubes was larger than the corresponding conducting polymer films.

  14. Experimental and theoretical characterization of implantable neural microelectrodes modified with conducting polymer nanotubes

    PubMed Central

    Abidian, Mohammad Reza; Martin, David C.

    2009-01-01

    Neural prostheses transduce bioelectric signals to electronic signals at the interface between neural tissue and neural microelectrodes. A low impedance electrode-tissue interface is important for the quality of signal during recording as well as quantity of applied charge density during stimulation. However, neural microelectrode sites exhibit high impedance because of their small geometric surface area. Here we analyze nanostructured-conducting polymers that can be used to significantly decrease the impedance of microelectrode typically by about two orders of magnitude and increase the charge transfer capacity of microelectrodes by three orders of magnitude. In this study poly(pyrrole) (PPy) and poly(3, 4- ethylenedioxythiophene) (PEDOT) nanotubes were electrochemically polymerized on the surface of neural microelectrode sites (1250 μm2). An equivalent circuit model comprising a coating capacitance in parallel with a pore resistance and interface impedance in series was developed and fitted to experimental results to characterize the physical and electrical properties of the interface. To confirm that the fitting parameters correlate with physical quantities of interface, theoretical equations were used to calculate the parameter values thereby validating the proposed model. Finally, an apparent diffusion coefficient was calculated for PPy film (29.2 ± 1.1 cm2/s), PPy nanotubes (72.4 ± 3.3 cm2/s), PEDOT film (7.4 ± 2.1 cm2/s), and PEDOT nanotubes (13.0 ± 1.8 cm2/s). The apparent diffusion coefficient of conducting polymer nanotubes was larger than the corresponding conducting polymer films. PMID:18093644

  15. 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.

  16. 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

  17. Synthesis and characterization of ion transport behavior in Cu2+-conducting nano composite polymer electrolyte membranes

    NASA Astrophysics Data System (ADS)

    Bala Sahu, Tripti; Sahu, Manju; Karan, Shrabani; Mahipal, Y. K.; Sahu, D. K.; Agrawal, R. C.

    2017-07-01

    Synthesis and characterization of ion transport behavior in Cu2+-conducting nano composite polymer electrolyte (NCPE) films: [90PEO: 10Cu(CF3SO3)2]  +  x CuO have been reported. NCPE films have been formed by hot-press casting technique using solid polymer electrolyte (SPE) film composition: [90PEO: 10Cu(CF3SO3)2] as 1st-phase host and nanoparticles of CuO in varying wt.(%) as 2nd-phase active filler. SPE: [90PEO: 10Cu(CF3SO3)2] was identified earlier as highest conducting film with room temperature conductivity (σ rt) ~ 3.0 x 10-6 S cm-1, which is three orders of magnitude higher than that of pure polymer host PEO with σ rt ~ 3.2  ×  10-9 S cm-1. Filler particle concentration dependent conductivity study revealed NCPE film: [90PEO: 10Cu(CF3SO3)2]  +  3%CuO as optimum conducting composition (OCC) exhibiting σ rt ~ 1.14  ×  10-5 S cm-1. Hence, by the fractional dispersal of 2nd-phase active filler into 1st-phase SPE host, σ-enhancement of approximately an order of magnitude has further been obtained. Ion transport behavior in NCPE OCC film has been characterized in terms of basic ionic parameters viz. ionic conductivity (σ), total ionic transference (t ion)/cationic (t +) numbers. Temperature dependent conductivity measurement has also been done to explain the mechanism of ion transport and to compute activation energy (E a). Materials characterization and hence, confirmation of complexation of salt in polymeric host and/or dispersal of filler particles in SPE host have been done by scanning electron microscopy (SEM), energy dispersive x-ray spectrometer (EDS), x-ray diffraction (XRD), Fourier transform infra-red (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). All-solid-state battery in the cell configuration: Cu (Anode) || SPE host/NCPE OCC film || C  +  I2  +  Electrolyte) (Cathode) has been fabricated and cell performance has been studied under two load resistances viz

  18. 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)

  19. 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)

  20. 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.

  1. 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.

  2. Synthesis and Characterization of Hydrazide-Linked and Amide-Linked Organic Polymers.

    PubMed

    Liu, Zhongshan; Ou, Junjie; Wang, Hongwei; You, Xin; Ye, Mingliang

    2016-11-23

    Four kinds of either hydrazide-linked or amide-linked polymers were facilely synthesized by using hydrazine, tetrakis(4-aminophenyl)methane (TAPM), terephthaloyl chloride (TPC), and trimesoyl chloride (TMC) as building blocks. The morphology, porosity, composition, and surface property of polymers were characterized by scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption measurement, (13)C/CP-MAS NMR, X-ray photoelectron spectroscopy, etc. The results indicated that building blocks had important effects on morphology and porosity. Poly(TMC-TAPM) synthesized with TMC and TAPM showed the highest surface area of 241.9 m(2) g(-1). In addition, note that a hollow structure with ∼20 nm wall thickness was formed in poly(TMC-hydrazine) prepared with TMC and hydrazine. Further study indicated that both carboxyl groups (-COOH) and hydrazide groups (-CONH-NH2) existed on the surface of poly(TMC-hydrazine), besides the mainly hydrazide linkage (-CONH-NHOC-). Taking advantages of good hydrophilicity and special functional groups on the surface, we finally adopted poly(TMC-hydrazine) to enrich glycopeptides from tryptic digest via both hydrophilic interaction chromatography method with identification of 369 unique N-glycosylation sites and hydrazide chemistry method with identification of 88 unique N-glycosylation sites, respectively.

  3. Characterization of a new natural fiber from Arundo donax L. as potential reinforcement of polymer composites.

    PubMed

    Fiore, V; Scalici, T; Valenza, A

    2014-06-15

    The aim of this paper is to study the possibility of using of Arundo donax L. fibers as reinforcement in polymer composites. The fibers are extracted from the outer part of the stem of the plant, which widely grows in Mediterranean area and is diffused all around the world. To use these lignocellulosic fibers as reinforcement in polymer composites, it is necessary to investigate their microstructure, chemical composition and mechanical properties. Therefore, the morphology of A. donax L. fibers was investigated through electron microscopy, the thermal behavior through thermogravimetric analysis and the real density through a helium pycnometer. The chemical composition of the natural fibers in terms of cellulose, hemicellulose, lignin, and ash contents was determinated by using standard test methods. The mechanical characterization was carried out through single fiber tensile tests and a reliability analysis of the experimental data was performed. Furthermore, a mathematical model was applied to investigate the relation between the transverse dimension of the fibers and the mechanical properties. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. 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.

  5. 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.

  6. 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.

  7. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Rupture threshold characterization of polymer-shelled ultrasound contrast agents subjected to static overpressure

    PubMed Central

    Chitnis, Parag V.; Lee, Paul; Mamou, Jonathan; Allen, John S.; Böhmer, Marcel; Ketterling, Jeffrey A.

    2011-01-01

    Polymer-shelled micro-bubbles are employed as ultrasound contrast agents (UCAs) and vesicles for targeted drug delivery. UCA-based delivery of the therapeutic payload relies on ultrasound-induced shell rupture. The fragility of two polymer-shelled UCAs manufactured by Point Biomedical or Philips Research was investigated by characterizing their response to static overpressure. The nominal diameters of Point and Philips UCAs were 3 μm and 2 μm, respectively. The UCAs were subjected to static overpressure in a glycerol-filled test chamber with a microscope-reticule lid. UCAs were reconstituted in 0.1 mL of water and added over the glycerol surface in contact with the reticule. A video-microscope imaged UCAs as glycerol was injected (5 mL∕h) to vary the pressure from 2 to 180 kPa over 1 h. Neither UCA population responded to overpressure until the rupture threshold was exceeded, which resulted in abrupt destruction. The rupture data for both UCAs indicated three subclasses that exhibited different rupture behavior, although their mean diameters were not statistically different. The rupture pressures provided a measure of UCA fragility; the Philips UCAs were more resilient than Point UCAs. Results were compared to theoretical models of spherical shells under compression. Observed variations in rupture pressures are attributed to shell imperfections. These results may provide means to optimize polymeric UCAs for drug delivery and elucidate associated mechanisms. PMID:21580800

  9. Rupture threshold characterization of polymer-shelled ultrasound contrast agents subjected to static overpressure.

    PubMed

    Chitnis, Parag V; Lee, Paul; Mamou, Jonathan; Allen, John S; Böhmer, Marcel; Ketterling, Jeffrey A

    2011-04-15

    Polymer-shelled micro-bubbles are employed as ultrasound contrast agents (UCAs) and vesicles for targeted drug delivery. UCA-based delivery of the therapeutic payload relies on ultrasound-induced shell rupture. The fragility of two polymer-shelled UCAs manufactured by Point Biomedical or Philips Research was investigated by characterizing their response to static overpressure. The nominal diameters of Point and Philips UCAs were 3 μm and 2 μm, respectively. The UCAs were subjected to static overpressure in a glycerol-filled test chamber with a microscope-reticule lid. UCAs were reconstituted in 0.1 mL of water and added over the glycerol surface in contact with the reticule. A video-microscope imaged UCAs as glycerol was injected (5 mL∕h) to vary the pressure from 2 to 180 kPa over 1 h. Neither UCA population responded to overpressure until the rupture threshold was exceeded, which resulted in abrupt destruction. The rupture data for both UCAs indicated three subclasses that exhibited different rupture behavior, although their mean diameters were not statistically different. The rupture pressures provided a measure of UCA fragility; the Philips UCAs were more resilient than Point UCAs. Results were compared to theoretical models of spherical shells under compression. Observed variations in rupture pressures are attributed to shell imperfections. These results may provide means to optimize polymeric UCAs for drug delivery and elucidate associated mechanisms.

  10. Fabrication and characterization of disordered polymer optical fibers for transverse Anderson localization of light.

    PubMed

    Karbasi, Salman; Frazier, Ryan J; Mirr, Craig R; Koch, Karl W; Mafi, Arash

    2013-07-29

    We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed polymer optical fiber is composed of 80,000 strands of poly (methyl methacrylate) (PMMA) and polystyrene (PS) that are randomly mixed and drawn into a square cross section optical fiber with a side width of 250 μm. Initially, each strand is 200 μm in diameter and 8-inches long. During the mixing process of the original fiber strands, the fibers cross over each other; however, a large draw ratio guarantees that the refractive index profile is invariant along the length of the fiber for several tens of centimeters. The large refractive index difference of 0.1 between the disordered sites results in a small localized beam radius that is comparable to the beam radius of conventional optical fibers. The input light is launched from a standard single mode optical fiber using the butt-coupling method and the near-field output beam from the disordered fiber is imaged using a 40X objective and a CCD camera. The output beam diameter agrees well with the expected results from the numerical simulations. The disordered optical fiber presented in this work is the first device-level implementation of 2D Anderson localization, and can potentially be used for image transport and short-haul optical communication systems.

  11. Synthesis and characterization of a novel chitosan-N-acetyl-homocysteine thiolactone polymer using MES buffer.

    PubMed

    Ferris, C; Casas, M; Lucero, M J; de Paz, M V; Jiménez-Castellanos, M R

    2014-10-13

    We report a new "green" approach to synthesize a novel thiolated chitosan conjugate, chitosan-N-acetyl-homocysteine thiolactone (chitosan-AcHcys) using a "Good's buffers", 2-(N-morpholino)ethanesulfonic acid (MES). After that, the crosslinked Xr-chitosan-AcHcys was obtained only in the presence of air, without other reactants. The chitosan-AcHcys spectrum shows a partial incorporation of the thiolactone onto the polymer backbone. The derivative thermogravimetric analysis confirmed that chitosan-AcHcys is slightly less stable than starting chitosan; however, the peak profile is broadened which is indicative of deeper changes in the thermal degradation process. Also, aqueous dispersions with different concentrations of the crosslinked material (Xr-chitosan-AcHcys) were prepared and rheologically characterized. All aqueous dispersions are viscoelastic fluid with shear-thinning behavior. The viscosity of the dispersions (1-7% of chitosan-AcHcys) increases as a function of polymer concentration. So, we have achieved to disperse a high concentration of thiolated-chitosan derivative in water with different rheological characteristics, which could affect the drug release. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. 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.

  13. 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.

  14. Rupture threshold characterization of polymer-shelled ultrasound contrast agents subjected to static overpressure

    NASA Astrophysics Data System (ADS)

    Chitnis, Parag V.; Lee, Paul; Mamou, Jonathan; Allen, John S.; Böhmer, Marcel; Ketterling, Jeffrey A.

    2011-04-01

    Polymer-shelled micro-bubbles are employed as ultrasound contrast agents (UCAs) and vesicles for targeted drug delivery. UCA-based delivery of the therapeutic payload relies on ultrasound-induced shell rupture. The fragility of two polymer-shelled UCAs manufactured by Point Biomedical or Philips Research was investigated by characterizing their response to static overpressure. The nominal diameters of Point and Philips UCAs were 3 μm and 2 μm, respectively. The UCAs were subjected to static overpressure in a glycerol-filled test chamber with a microscope-reticule lid. UCAs were reconstituted in 0.1 mL of water and added over the glycerol surface in contact with the reticule. A video-microscope imaged UCAs as glycerol was injected (5 mL/h) to vary the pressure from 2 to 180 kPa over 1 h. Neither UCA population responded to overpressure until the rupture threshold was exceeded, which resulted in abrupt destruction. The rupture data for both UCAs indicated three subclasses that exhibited different rupture behavior, although their mean diameters were not statistically different. The rupture pressures provided a measure of UCA fragility; the Philips UCAs were more resilient than Point UCAs. Results were compared to theoretical models of spherical shells under compression. Observed variations in rupture pressures are attributed to shell imperfections. These results may provide means to optimize polymeric UCAs for drug delivery and elucidate associated mechanisms.

  15. Recent Advances in Characterization of Lignin Polymer by Solution-State Nuclear Magnetic Resonance (NMR) Methodology

    PubMed Central

    Wen, Jia-Long; Sun, Shao-Long; Xue, Bai-Liang; Sun, Run-Cang

    2013-01-01

    The demand for efficient utilization of biomass induces a detailed analysis of the fundamental chemical structures of biomass, especially the complex structures of lignin polymers, which have long been recognized for their negative impact on biorefinery. Traditionally, it has been attempted to reveal the complicated and heterogeneous structure of lignin by a series of chemical analyses, such as thioacidolysis (TA), nitrobenzene oxidation (NBO), and derivatization followed by reductive cleavage (DFRC). Recent advances in nuclear magnetic resonance (NMR) technology undoubtedly have made solution-state NMR become the most widely used technique in structural characterization of lignin due to its versatility in illustrating structural features and structural transformations of lignin polymers. As one of the most promising diagnostic tools, NMR provides unambiguous evidence for specific structures as well as quantitative structural information. The recent advances in two-dimensional solution-state NMR techniques for structural analysis of lignin in isolated and whole cell wall states (in situ), as well as their applications are reviewed. PMID:28809313

  16. 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.

  17. [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.

  18. Characterization of steel fiber and/or polymer concrete mixes and applications to slender rectangular and I-beams

    NASA Astrophysics Data System (ADS)

    Ahmed, Ashraf Ibrahim

    This dissertation presents results from experimental studies related to polymer modified concrete, steel fiber reinforced concrete, and steel fiber/polymer modified concrete. As a first stage of this research, the properties of different concrete mixes were characterized. These mixes were: plain concrete, steel fiber concrete with fiber volume fraction of 1%, polymer modified concrete with 1% to 7.5% solids of polymer, and steel fiber/polymer modified concrete with 1% to 7.5% polymer solids and I% steel fiber fraction. Concrete cylinders and 4 x 4 inches beams were tested under compressive, tensile, flexural, and bar pull-out loadings. In the second phase of this research, slender beams with a depth to width ratio of three were tested under four point loading for shear and flexure. Half I-beams, with gross aspect ratio of four and web aspect ratio of three were tested under the combined loading of bending, shear, and torsion. Lateral eccentric loads were applied transversely in the shallow direction to the 3 x 9 inches beams and the half I-beams. Dog bone shaped reinforced and un-reinforced specimens with 3 x 3 inches square sections were tested under pure torsional loading. The addition of 1% steel fibers alone or with 5% solids of polymers to concrete mixes improved their toughness and ductility. The contribution of steel fibers to bending, shear, and torsion in slender and half I-beams is presented. The ACI code methods for calculating the torsional, shear, and flexural resistance of beams are compared to the experimental results. Post crack analysis performed on the slender beams and half I-beams indicated that the tested specimens could carry 70% of the maximum applied loads after initial concrete cracking and failure. The reduction in the tensile stresses of stirrups and longitudinal reinforcing bars, due to the steel fibers and polymer, are presented. Fibers and polymers increase bending and toughness in concrete.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    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.

  10. 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%).

  11. Polymer nanocomposite nanomechanical cantilever sensors: material characterization, device development and application in explosive vapour detection

    NASA Astrophysics Data System (ADS)

    Seena, V.; Fernandes, Avil; Pant, Prita; Mukherji, Soumyo; Ramgopal Rao, V.

    2011-07-01

    This paper reports an optimized and highly sensitive piezoresistive SU-8 nanocomposite microcantilever sensor and its application for detection of explosives in vapour phase. The optimization has been in improving its electrical, mechanical and transduction characteristics. We have achieved a better dispersion of carbon black (CB) in the SU-8/CB nanocomposite piezoresistor and arrived at an optimal range of 8-9 vol% CB concentration by performing a systematic mechanical and electrical characterization of polymer nanocomposites. Mechanical characterization of SU-8/CB nanocomposite thin films was performed using the nanoindentation technique with an appropriate substrate effect analysis. Piezoresistive microcantilevers having an optimum carbon black concentration were fabricated using a design aimed at surface stress measurements with reduced fabrication process complexity. The optimal range of 8-9 vol% CB concentration has resulted in an improved sensitivity, low device variability and low noise level. The resonant frequency and spring constant of the microcantilever were found to be 22 kHz and 0.4 N m - 1 respectively. The devices exhibited a surface stress sensitivity of 7.6 ppm (mN m - 1) - 1 and the noise characterization results support their suitability for biochemical sensing applications. This paper also reports the ability of the sensor in detecting TNT vapour concentration down to less than six parts per billion with a sensitivity of 1 mV/ppb.

  12. Polymer nanocomposite nanomechanical cantilever sensors: material characterization, device development and application in explosive vapour detection.

    PubMed

    Seena, V; Fernandes, Avil; Pant, Prita; Mukherji, Soumyo; Rao, V Ramgopal

    2011-07-22

    This paper reports an optimized and highly sensitive piezoresistive SU-8 nanocomposite microcantilever sensor and its application for detection of explosives in vapour phase. The optimization has been in improving its electrical, mechanical and transduction characteristics. We have achieved a better dispersion of carbon black (CB) in the SU-8/CB nanocomposite piezoresistor and arrived at an optimal range of 8-9 vol% CB concentration by performing a systematic mechanical and electrical characterization of polymer nanocomposites. Mechanical characterization of SU-8/CB nanocomposite thin films was performed using the nanoindentation technique with an appropriate substrate effect analysis. Piezoresistive microcantilevers having an optimum carbon black concentration were fabricated using a design aimed at surface stress measurements with reduced fabrication process complexity. The optimal range of 8-9 vol% CB concentration has resulted in an improved sensitivity, low device variability and low noise level. The resonant frequency and spring constant of the microcantilever were found to be 22 kHz and 0.4 N m(-1) respectively. The devices exhibited a surface stress sensitivity of 7.6 ppm (mN m(-1))(-1) and the noise characterization results support their suitability for biochemical sensing applications. This paper also reports the ability of the sensor in detecting TNT vapour concentration down to less than six parts per billion with a sensitivity of 1 mV/ppb.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level.

    PubMed

    Habuchi, Satoshi; Yamamoto, Takuya; Tezuka, Yasuyuki

    2016-09-26

    We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single molecule level. An electrostatic self-assembly and covalent fixation (ESA-CF) process is used for the synthesis of the cyclic poly(tetrahydrofuran) (poly(THF)). The diffusive motion of individual cyclic polymer chains in a melt state is visualized using single molecule fluorescence imaging by incorporating a fluorophore unit in the cyclic chains. The diffusive motion of the chains is quantitatively characterized by means of a combination of mean-squared displacement (MSD) analysis and a cumulative distribution function (CDF) analysis. The cyclic polymer exhibits multiple-mode diffusion which is distinct from its linear counterpart. The results demonstrate that the diffusional heterogeneity of polymers that is often hidden behind ensemble averaging can be revealed by the efficient synthesis of the cyclic polymers using the ESA-CF process and the quantitative analysis of the diffusive motion at the single molecule level using the MSD and CDF analyses.

  18. 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

  19. 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.

  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. 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.

  2. 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.

  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. Multifaceted characterization of cell wall decomposition products formed during ammonia fiber expansion (AFEX) and dilute acid based pretreatments.

    PubMed

    Chundawat, Shishir P S; Vismeh, Ramin; Sharma, Lekh N; Humpula, James F; da Costa Sousa, Leonardo; Chambliss, C Kevin; Jones, A Daniel; Balan, Venkatesh; Dale, Bruce E

    2010-11-01

    Decomposition products formed/released during ammonia fiber expansion (AFEX) and dilute acid (DA) pretreatment of corn stover (CS) were quantified using robust mass spectrometry based analytical platforms. Ammonolytic cleavage of cell wall ester linkages during AFEX resulted in the formation of acetamide (25mg/g AFEX CS) and various phenolic amides (15mg/g AFEX CS) that are effective nutrients for downstream fermentation. After ammonolysis, Maillard reactions with carbonyl-containing intermediates represent the second largest sink for ammonia during AFEX. On the other hand, several carboxylic acids were formed (e.g. 35mg acetic acid/g DA CS) during DA pretreatment. Formation of furans was 36-fold lower for AFEX compared to DA treatment; while carboxylic acids (e.g. lactic and succinic acids) yield was 100-1000-fold lower during AFEX compared to previous reports using sodium hydroxide as pretreatment reagent. Copyright 2010 Elsevier Ltd. All rights reserved.

  5. Fabrication and characterization of biomimetic ceramic/polymer composite materials for dental restoration.

    PubMed

    Petrini, Morena; Ferrante, Maurizio; Su, Bo

    2013-04-01

    Conventional dental composites with randomly dispersed inorganic particles within a polymer matrix fail to recapitulate the aligned and anisotropic structure of the dentin and enamel. The aim of the study was to produce a biomimetic composite consisting of a ceramic preform with graded and continuously aligned open pores, infiltrated with epoxy resin. The freeze casting technique was used to obtain the hierarchically structured architecture of the ceramic preforms. Optical and scanning electron microscopy (SEM) and differential thermal analysis and thermogravimetry (TG-DTA) were used to characterize the samples. Three point bending test and compression test were also performed. All analysis confirmed that the biomimetic composite was characterized by a multi-level hierarchical structure along the freezing direction. In the bottom layers close to the cooling plate (up to 2mm thick), a randomly packed ceramic with closed pores were formed, which resulted in incomplete infiltration with resin and resultant poor mechanical propertiesof the composite. Above 2mm, all ceramic samples showed an aligned structure with an increasing lamellae spacing (wavelength) and a decreasing wall thickness. Mechanical tests showed that the properties of the composites made from ceramic preforms above 2mm from cooling plate are similar to those of the dentin. The fabrication processing reported in this work offers a viable route for the fabrication of biomimetic composites, which could be potentially used in a range of dental restorations to compete with the current dental composites and ceramics. Copyright © 2012 Academy of Dental Materials. All rights reserved.

  6. 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.

  7. 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.

  8. 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.

  9. 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%.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

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

    PubMed

    Zeis, Roswitha

    2015-01-01

    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 fuel cell

  18. 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

  19. 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

  20. Reactive molecular dynamics of network polymers: Generation, characterization and mechanical properties

    NASA Astrophysics Data System (ADS)

    Shankar, Chandrashekar

    The goal of this research was to gain a fundamental understanding of the properties of networks created by the ring opening metathesis polymerization (ROMP) of dicyclopentadiene (DCPD) used in self-healing materials. To this end we used molecular simulation methods to generate realistic structures of DCPD networks, characterize their structures, and determine their mechanical properties. Density functional theory (DFT) calculations, complemented by structural information derived from molecular dynamics simulations were used to reconstruct experimental Raman spectra and differential scanning calorimetry (DSC) data. We performed coarse-grained simulations comparing networks generated via the ROMP reaction process and compared them to those generated via a RANDOM process, which led to the fundamental realization that the polymer topology has a unique influence on the network properties. We carried out fully atomistic simulations of DCPD using a novel algorithm for recreating ROMP reactions of DCPD molecules. Mechanical properties derived from these atomistic networks are in excellent agreement with those obtained from coarse-grained simulations in which interactions between nodes are subject to angular constraints. This comparison provides self-consistent validation of our simulation results and helps to identify the level of detail necessary for the coarse-grained interaction model. Simulations suggest networks can classified into three stages: fluid-like, rubber-like or glass-like delineated by two thresholds in degree of reaction alpha: The onset of finite magnitudes for the Young's modulus, alphaY, and the departure of the Poisson ration from 0.5, alphaP. In each stage the polymer exhibits a different predominant mechanical response to deformation. At low alpha < alphaY it flows. At alpha Y < alpha < alphaP the response is entropic with no change in internal energy. At alpha > alphaP the response is enthalpic change in internal energy. We developed graph theory

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. Modified detrended fluctuation analysis based on empirical mode decomposition for the characterization of anti-persistent processes

    NASA Astrophysics Data System (ADS)

    Qian, Xi-Yuan; Gu, Gao-Feng; Zhou, Wei-Xing

    2011-11-01

    Detrended fluctuation analysis (DFA) is a simple but very efficient method for investigating the power-law long-term correlations of non-stationary time series, in which a detrending step is necessary to obtain the local fluctuations at different timescales. We propose to determine the local trends through empirical mode decomposition (EMD) and perform the detrending operation by removing the EMD-based local trends, which gives an EMD-based DFA method. Similarly, we also propose a modified multifractal DFA algorithm, called an EMD-based MFDFA. The performance of the EMD-based DFA and MFDFA methods is assessed with extensive numerical experiments based on fractional Brownian motion and multiplicative cascading process. We find that the EMD-based DFA method performs better than the classic DFA method in the determination of the Hurst index when the time series is strongly anticorrelated and the EMD-based MFDFA method outperforms the traditional MFDFA method when the moment order q of the detrended fluctuations is positive. We apply the EMD-based MFDFA to the 1 min data of Shanghai Stock Exchange Composite index, and the presence of multifractality is confirmed. We also analyze the daily Austrian electricity prices and confirm its anti-persistence.

  6. Rheological Characterization of Molten Polymer-Drug Dispersions as a Predictive Tool for Pharmaceutical Hot-Melt Extrusion Processability.

    PubMed

    Van Renterghem, Jeroen; Vervaet, Chris; De Beer, Thomas

    2017-08-15

    The aim of this study was to investigate (i) the influence of drug solid-state (crystalline or dissolved in the polymer matrix) on the melt viscosity and (ii) the influence of the drug concentration, temperature and shear rate on polymer crystallization using rheological tests. Poly (ethylene oxide) (PEO) (100.000 g/mol) and physical mixtures (PM) containing 10-20-30-40% (w/w) ketoprofen or 10% (w/w) theophylline in PEO were rheologically characterized. Rheological tests were performed (frequency and temperature sweeps in oscillatory shear as well as shear-induced crystallization experiments) to obtain a thorough understanding of the flow behaviour and crystallization of PEO-drug dispersions. Theophylline did not dissolve in PEO as the complex viscosity (η*) of the drug-polymer mixture increased as compared to that of neat PEO. In contrast, ketoprofen dissolved in PEO and acted as a plasticizer, decreasing η*. Acting as a nucleating agent, theophylline induced the crystallization of PEO upon cooling from the melt. On the other hand, ketoprofen inhibited crystallization upon cooling. Moreover, higher concentrations of ketoprofen in the drug-polymer mixture increasingly inhibited polymer crystallization. However, shear-induced crystallization was observed for all tested mixtures containing ketoprofen. The obtained rheological results are relevant for understanding and predicting HME processability (e.g., barrel temperature selection) and downstream processing such as injection moulding (e.g., mold temperature selection).

  7. 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.

  8. 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.

  9. 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.

  10. Characterization of Highly Sulfonated SIBS Polymer Partially Neutralized With Mg(+2) Cations

    DTIC Science & Technology

    2008-08-01

    97% of all styrene groups in the polymer were modified with sulfonic acid group as was verified by titration and elemental analysis. The...the acidic hydrogens are exchanged out with Mg+2 ions creating an ionic crosslink between the neighboring sulfonic groups. Initially, attempts were...not appear in the unsulfonated polymer. In particular, three distinct bands associated with sulfonic acid were identified in the sulfonated polymers

  11. 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.

  12. 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.

  13. Screening of lipid carriers and characterization of drug-polymer-lipid interactions for the rational design of polymer-lipid hybrid nanoparticles (PLN).

    PubMed

    Li, Yongqiang; Taulier, Nicolas; Rauth, Andrew M; Wu, Xiao Yu

    2006-08-01

    The thermodynamics and solid state properties of components and their interactions in a formulation for polymer-lipid hybrid nanoparticles (PLN) were characterized for screening lead lipid carriers and rational design of PLN. Verapamil HCI (VRP) was chosen as a model drug and dextran sulfate sodium (DS) as a counter-ionic polymer. Solubility parameters of VRP, VRP-DS complex, and various lipids were calculated and partition of VRP and VRP-DS in lipids was determined. Thermodynamics of VRP binding to DS was determined by isothermal titration calorimetry (ITC). The solid state properties of individual components and their interactions were characterized using differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). Dodecanoic acid (DA) was identified as the best lipid carrier among all lipids tested based on the solubility parameters and partition coefficients. VRP-DS complexation was a thermodynamically favorable process. Maximum binding capacity of DS and the highest drug loading capacity of DA were obtained at an equal ionic molar ratio of DS to VRP. In the PLN formulation, DA remained its crystal structure but had a slightly lower melting point, while VRP-DS complex was in an amorphous form. Drug loading efficiency and capacity of a lipid matrix depend on the VRP-DS binding and the interactions of the complex with the lipid. A combined analysis of solubility parameters and partition coefficients is useful for screening lipid candidates for PLN preparation.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. A Novel Method to Characterize Nanorod Orientation and Aggregation in Polymer Nanocomposites

    NASA Astrophysics Data System (ADS)

    Glor, Ethan; Ferrier, Robert; Composto, Russell; Fakhraai, Zahra

    Gold nanorods provide an ideal system for the systematic change of optical properties through changes in the rod aspect ratio. Furthermore, the dispersity and orientation of the nanorods within a polymer matrix greatly affects the optical properties of the composites. Here, we use spectroscopic ellipsometry to characterize the properties of nanocomposite thin films. The optical properties of the nanorod are modeled as an effective index of refraction for a disordered meta-material. This effective medium index is then related to the longitudinal surface plasmon resonance (LSPR) of the nanorods. The degree of birefringence in the LSPR frequency, as determined by variable angle ellipsometry measurements, can help determine the average orientation of the rods in the thin film as well as the degree of aggregation. With this method, one can quickly and accurately define the average orientation and average aggregation of nanorods within a nanocomposite with a single measurement. Ellipsometry also allows us to perform in-situ variable temperature measurements to monitor properties such as nanoparticle shape and the glass transition temperature of the matrix. Acknowledgement: NSF-PIRE-1545884, MRSEC (NSF-DMR-11-20901).

  1. 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.

  2. 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

  3. 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.

  4. 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.

  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 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. Nanocrystalline hydroxyapatite powders by a chitosan-polymer complex solution route: Synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Klinkaewnarong, Jutharatana; Swatsitang, Ekaphan; Maensiri, Santi

    2009-05-01

    Nanocrystalline hydroxyapatite (HAp) powders were successfully synthesized by a simple method using chitosan-polymer complex solution. To obtain HAp nanopowders, the prepared precursor was calcined in air at 400-800 °C for 2 h. The phase composition of the calcined samples was studied by X-ray diffraction (XRD) technique. The XRD results confirmed the formation of HAp phase with a small trace of monotite phase. With increasing calcination temperature, the crystallinity of the HAp increased, showing the hexagonal structure of HAp with the lattice parameter a in a range of 0.94030-0.94308 nm and c of 0.68817-0.68948 nm. The particle sizes of the powder were found to be 55.02-73.36 nm as evaluated by the XRD line broadening method. The chemical composition of the calcined powders was characterized by FTIR spectroscopy. The peaks of the phosphate carbonate and hydroxyl vibration modes were observed in the FTIR spectra for all the calcined powders. TEM investigation revealed that the prepared HAP samples consisted of rod-like nanoparticles having the particle size in the range of 100-300 nm. The corresponding selected-area electron diffraction (SAED) analysis further confirmed the formation of hexagonal structure of HAp.

  15. 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.

  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. 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.

  18. 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.

  19. Thermal decomposition of sewage sludge under N2, CO2 and air: Gas characterization and kinetic analysis.

    PubMed

    Hernández, Ana Belén; Okonta, Felix; Freeman, Ntuli

    2017-07-01

    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. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. 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.

  1. 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.

  2. 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.

  3. Sub-10-Minute Characterization of an Ultrahigh Molar Mass Polymer by Multi-detector Hydrodynamic Chromatography

    USDA-ARS?s Scientific Manuscript database

    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...

  4. 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.

  5. 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.

  6. 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).

  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. 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.

  9. Assessment and characterization of the total geometric uncertainty in Gamma Knife radiosurgery using polymer gels.

    PubMed

    Moutsatsos, A; Karaiskos, P; Petrokokkinos, L; Sakelliou, L; Pantelis, E; Georgiou, E; Torrens, M; Seimenis, I

    2013-03-01

    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. 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. MR spatial distortions stemming from main field (B0) 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 geometric uncertainty ranged from

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. Processing and characterization of natural cellulose fibers/thermoset polymer composites.

    PubMed

    Thakur, Vijay Kumar; Thakur, Manju Kumari

    2014-08-30

    Recently natural cellulose fibers from different biorenewable resources have attracted the considerable attraction of research community all around the globe owing to their unique intrinsic properties such as biodegradability, easy availability, environmental frie