bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of 4,4’-bis(6-hydroxyhexoxy)biphenyl moieties on properties of polyurethanes based on 4,4’-methylenebis(cyclohexyl isocyanate)
Authors: Łazarewicz Tymon , Haponiuk Józef T. , Balas Adolf 
Published: August 2014

AbstractTwo series of polyurethanes (PUs) were synthesized from a low molecular weight diol - 4,4’-bis(6-hydroxyhexoxy)biphenyl (BH6), a high molecular weight diol - poly(1,6-hexylene adipate)diol (PHA) and 4,4’-methylenebis (cyclohexyl isocyanate) (HMDI) using two fractions of different trans,trans isomer content (uT), respectively: 16%, 46%. The effect of low molecular diol content (uB) in the total mass of the diols used for synthesis on properties of PUs was investigated by DSC, DTA, TGA, polarization microscopy, WAXS, DMTA and tensile testing. For segmented PUs microphase separation is observed and melting temperatures of hard segment (HS) microphases are almost constant within the series for uB≥ 40%. The growth of hard segment content (uHS) induces rectilinear growth of crystallization enthalpy of HS microphases. PUs of uT= 46% show birefringence of HS microphases at uBB ≥ 40%. Glass transition temperatures of HS microphases shift towards lower values with a decrease of uB. PUs of u B = 80 and 100% are stiff, for 20 - 60% elastomeric properties are observed, and in absence of low molecular diol moieties (uB= 0%) plastic behaviour is shown when stretched. Phase inversion is observed between u B BB = 60 and 80%. Thermal stability of PUs (by TGA and DTA) does not depend on uBand uT.
Synthesis of highly sulfonated polystyrene-based block copolymers soluble in tetrahydrofuran
Authors: Janata Miroslav , Kůdela Vlastimil , Gromadzki Daniel , Štěpánek Petr , Nallet Frédéric , Diat Olivier , Vlček Petr , Toman Luděk 
Published: August 2014

AbstractPolystyrene-block-polyisoprene with hydrogenated polyisoprene block (Shellvis 50) was sulfonated to a high degree (up to 42 mol% of styrene units) using acetyl sulfate as sulfonation agent in various chlorinated solvents. Membranes were prepared from the tetrahydrofuran solution of the sulfonated copolymer by casting. The membranes were characterized by conductivity and SAXS measurements.
A Novel Approach For Synthesizing Composite Polymer Electrolytes with a Stereocomplex Poly(methyl meth acrylate) for electrochromic devices
Authors: Ahmad Shahzada , Ahmad Sharif , Agnihotry S.A. 
Published: August 2014

AbstractA novel approach has been adopted for synthesizing composite polymer electrolytes with a blend of atactic poly(methyl methacrylate) (a-PMMA) and isotactic PMMA (i-PMMA) owing to their ability to form stereocomplex structures, especially double helix like structures. Nanocomposite polymeric electrolytes based on gel polymeric electrolyte (GPE) consisting of stereocomplex PMMA, propylene carbonate (PC) and LiClO4 has been synthesized. For the stabilization of polymer electrolytes and for good processability, fumed silica nanoparticles have been added in different proportions up to 6 wt% to GPE resulting in composite polymeric electrolytes (CPEs). Thermally stable, low volatile CPEs without the cost on electrochemical stability can thus be obtained, being promising candidates as polymeric electrolytes in many electrochemical devices in general, and in particular electrochromic windows.
Functionalization of poly(vinyl alcohol) by addition of methacryloyl groups: characterization by FTIR and NMR and optimization of reaction conditions by RSM
Authors: Crispim Edson G. , Piai Juliana F. , Schüquel Ivânia T. A. , Rubira Adley F. , Muniz Edvani C. 
Published: August 2014

AbstractThe modification of poly(vinyl alcohol) (PVA) with glycidyl methacrylate (GMA) in DMSO catalyzed by TEMED is reported in this paper. PVA was dissolved in DMSO and reacted with GMA at 30 ºC in a closed vessel under N2 gas bubbling for 24 hours. The reaction was characterized by FTIR and NMR (1H, 13C/DEPT and HETCOR) spectroscopies. The reaction occurs by transesterification through the insertion of methacryloyl groups into PVA chains and probably with the formation of glycidol as a by-product. The degree of substitution (DS) that represents the number of methacryloyl groups inserted was determined through 1H NMR spectra based on the ratio between the averaged area due to the vinyl hydrogen from methacryloyl groups at δ̣ 5.6 ppm and δ 6.0 ppm and the total area of the vinyl hydrogen and hydroxyl hydrogen of PVA. By use of response surface methodology the experimental conditions were optimized. The optimum conditions were 62 ºC with a reaction time of 6 hours. In these optimized conditions, the reactions using the molar ratios [-OH(PVA)/GMA] equal to 1/0.10, 1/0.25, 1/0.50, 1/0.75 and 1/1 were investigated. The response surface was based on the model DS= −19.70 + 6.09x10−1T +1.93 t − 3.89x10−3 T2 − 5.21x10−2t2 − 2.14x10−2 T * t, where T is the temperature (°C) and t the reaction time (hours). This model explained 99.20 % of the 99.64 % explainable statistical data. Using the optimized conditions, it is possible to produce a desired modified PVA, (or PVA-Ma), because DS raises linearly to the ratio [-OH(PVA)/GMA] up to 25 mol-% and the respective yield ranged from 83 to 92 %. It is difficult to obtain more than 50 mol-% substitution of PVA hydroxyl by methacryloyl groups even in these optimized conditions due to increased steric hindrance by the large number of the methacryloyl groups inserted into PVA.
Preparation and characterization of post-derivatives from functional polystyrene (ATRP) with p-nitroanilineazomethine phenol and their thermal and optical study
Authors: Yu Xifei , Zhang Guo , Shi Tongfei , Dutta P.K. , An Lijia 
Published: August 2014

AbstractThe functional polystyrene, (Cl-PS)2-CHCOOCH2CH2OH (designated as XPSt and coded P2) was prepared by ATRP at 1300C using CuCl and bipyridine as catalysts, 2,2-dichloro acetate-ethylene glycol (DCAG) as multifunctional initiator and THF as solvent. 4-Nitoroaniline azomethine-4’ phenol (P1) as chromophores were covalently linked to the functional end groups of the polymer by using simple displacement reaction. The functional polystyrenes, namely XPSt (P2) and (PS)2-CHCOOCH2CH2OH, designated as X-PSt and coded P3 and their post-derivatives, namely, DXPSt (P4) and DX-PSt (P5) respectively were characterized by IR, NMR and UV spectroscopies, gel permeation chromatography (GPC) and thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), polarising optical microscopy (POM) and XRD studies. DSC showed that incorporation of chromophores in the side chains of polymers towards the polystyrene moiety increases the rigidity of the polymer and subsequently, its glass transition temperature; however the incorporation of side chain towards the alcoholic functional group decreases the glass transition temperature. The post derivatives do not play any significant role to increase the thermal stability (TGA). There was evidence for liquid crystalline properties in the resulting polymer derivative DXPSt (P4) as observed from POM study, which defines the alignment of chromophores into the polymers. The XRD study shows crystalline behaviour of the polymer derivative, P4. The polymer derivative, DXPSt (P5) does not show such behaviour and this may be due to the bonding of azomethine towards the short chain alcoholic telechelic alcoholic sides of the copolymer.
Modification of poly(L-lactic acid) with L-lactic acid / citric acid oligomers
Authors: Jiang Yan , Bai Yun , Chen Man , Yao Fanglian , Zhang Haiyue , De Yao Kang 
Published: August 2014

AbstractThe surface modification of polymeric biomaterials can be achieved by surface immobilization of bioactive molecules, increased hydrophilicity, and balanced hydrophilicity and hydrophobicity. Poly (L-Lactic Acid) (PLLA) is hydrophobic and possesses no reactive groups in the structure. In the present work, an effort has been made to blend PLLA with functionalized L-lactic acid / citric acid oligomer (PLCA) in order to improve the hydrophilicity of the PLLA. The compatibility of PLLA and PLCA was studied by using differential scanning calorimetry (DSC). The blends were also characterized for their water absorption, contact angle, tensile strength and hydrolytic degradation. The DSC results showed that PLLA/PLCA blends exhibited a single glass transition temperature (Tg), which lies in between that of PLLA and PLCA, thus asserting compatibility at the molecular level. The studies on water absorption, contact angle and hydrolytic degradation showed that addition of PLCA to PLLA enhanced the hydrophilicity of PLLA.
Effect of Nematic Order Coupling on the Phase Diagrams of Side-Chain Polymer Gels with Liquid Crystal Solvent
Authors: Vendamme Richard , Maschke Ulrich 
Published: August 2014

AbstractWe have explored the influence of nematic order coupling on the swelling and phase diagram of polymer networks in nematogenic low molar weight LC solvent, in view of the increasing importance of such systems in advanced optical devices. Firstly, one isotropic polyacrylate network and one nematic sidechain polyacrylate network is prepared. Immersing these two networks in nematic LC solvent lead to the formation of well-defined polymer gels with LC solvents and allow us to establish the phase diagram of these relatively new materials in the concentration-temperature frame. Results were critically analysed as a function of temperature and network nature (isotropic or nematic). We demonstrate that in the case of gel made from an isotropic polymer network, the LC solvents fails to form a nematic phase inside the gel due to the lack of anisotropic coupling. Moreover, in that case the gel shrinks below TNI Solvent because of a strong “entropic” incompatibility between the isotropic flexible coils and the LC nematogens. However, the situation is drastically different in the case of LC side-chain network due to a strong coupling of the nematic order between the mesogens of the solvents and those of the polymer backbone. In that case, tremendous distortions appear in the phase-diagram, in which we especially emphasize the apparition of a stable nematic gel phase and a miscibility gap between TNI Solvent and TNI Gel. Finally, results are critically examined and compared to the few studies found in the literature.
One-pot synthesis of PMMA/montmorillonite nanocomposites
Authors: Kiersnowski Adam , Trelinska-Wlazlak Maria , Dolega Justyna , Piglowski Jacek 
Published: August 2014

AbstractThis article describes simple preparation methods of poly(methyl methacrylate) (PMMA)/synthetic montmorillonite nanocomposites by single-step insitu polymerizations. Compatibility between PMMA and the silicate was ensured by an addition of (3-acrylamidepropyl) trimethylammonium chloride (AAPTMA). The work also compares how different synthetic routes, namely emulsion and solution polymerization, affect the structure as well as thermal and mechanical properties of obtained nanocomposites. The results of structural investigations clearly show, that both the techniques lead to intercalated nanocomposites, but emulsion polymerization allows more effective deflocculating and intercalating of the clay with acrylic copolymers. The addition of small amounts of layered silicates causes an increase in thermal stability and stiffness of the materials. It is demonstrated that at 5 wt. % of the filler, the temperature of 10 % weight loss was shifted up by nearly 50 K in comparison to the neat PMMA. In the same sample, the Young’s modulus of the material was found to be increased by 26 %.
Dynamic Simulation and Modelling of Bulk Polymerization of Ethylene Using Bi-functional initiators
Authors: Gharagheizi Farhad 
Published: August 2014

AbstractA dynamic simulation and modelling of ethylene bulk polymerization in an autoclave reactor are presented in this paper, based on a kinetic model. This simulation is done for mono- and bi-functional initiators, and results show that application of the bi-functional initiators cause an increase in ethylene conversion. The presented model shows very good results for high temperature and low temperature, in comparison with experimental data in the literature.
Surface-Ionized thermosensitive poly(N-isopropylacryl amide) hydrogels with faster response
Authors: Xin-Cai Xiao 
Published: August 2014

AbstractPoly(N-isopropylacrylamide) hydrogels have been successfully modified by concentrated sulfuric acid for the first time. The modified hydrogels displayed faster, larger magnitude and hydration/dehydration dynamic response to temperature cycling without increasing the lower critical solution temperature (LCST). These contributions were attributed to sulphate ester groups resulting from terminal hydroxyl groups of poly(N-isopropylacrylamide). These results may lead to technological application for temperature-responsive thin film and microgel particles with higher surface-to-volume ratio.
Synthesis and characterization of poly(ethylene-vinyl alcohol)-g-poly(phenyl ethyl methacrylate) copolymers by a grafting onto method
Authors: Azam M. , John V. Dawkins 
Published: August 2014

AbstractGraft copolymers of poly(ethylene-vinyl alcohol)-g-poly(phenyl ethyl methacrylate) copolymers were prepared by a grafting onto method in two steps. In the first step carboxyl terminated poly(phenyl ethyl methacrylate) (PPHETMA) were prepared by solution radical polymerization using 4,4-azobis(cyanovaleric acid) (ACVA) as initiator and thioglycolic acid (TGA) as matched chain transfer agent and then converting carboxyl groups into acid chloride terminated prepolymer by reacting with oxalyl chloride. In the second step acid chloride terminated prepolymers were reacted to the ethylene-vinyl alcohol (EVOH) backbone. Grafting was confirmed by Size Exclusion Chromatography (SEC), Fourier Transfer Infrared spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopy. Thermal properties of the graft copolymers were studied by Differential Scanning Calorimetery (DSC) and Dynamic Mechanical Thermal Analysis (DMTA).
Dynamics of Complexation of a Charged Dendrimer by Linear Polyelectrolyte: Computer Modelling
Authors: Lyulin Sergey , Darinskii Anatolij , Lyulin Alexey 
Published: August 2014

AbstractBrownian-dynamics simulations have been performed for complexes formed by a charged dendrimer and a long oppositely charged linear polyelectrolyte when overcharging phenomenon is always observed. After complex formation the orientational mobility of the individual dendrimer bonds, the fluctuations of the dendrimer size, and the dendrimer rotational diffusion have been simulated. Corresponding relaxation times do not depend on the linear-chain length in a complex and are close to those for a single neutral dendrimer. At the same time fluctuations of the size of a complex are completely defined by the corresponding fluctuations of a linear polyelectrolyte size. Adsorbed polyelectrolyte practically does not feel the rotation of a dendrimer; simulated complexes may be considered as nuts with light core (dendrimer) and heavy shell (adsorbed linear polymer); the electrostatic contacts between dendrimer and oppositely charged linear polymer are easily broken due to the very fast dendrimer-size fluctuations.
Kinetics modeling of the reaction for an Epoxy/PMMA/MMT ternary system
Authors: Hernandez Marcelo , Dupuy Jérôme , Duchet Jannick , Sautereau Henry 
Published: August 2014

Abstract The effect of thermoplastic PMMA and clay Cloisite 30B addition on the cure kinetics of an epoxy/amine thermosetting system was investigated using differential scanning calorimetry (DSC) and modelled using a single kinetic model. For obtaining a good agreement between the experimental results and theoretical modeling, it was necessary to separate the ternary system in two formulations: matrix/PMMA and matrix/clay systems. It appeared that the addition of PMMA delays the reaction up to the phase separation phenomenon due to a dilution effect of the reactive species. In opposition, the presence of clays accelerates the reaction (probably due to a catalytic effect of some metals ions introduced with the clay) but it has no sensitive effect on the cloud point conversion in the presence of PMMA. The modeling results are in good agreement with those experimentally obtained.
Polyaniline-modified Montmorillonite Nanocomposite as an Actuator
Authors: Golmohammadi Masumeh , Kokabi Mehrdad , Entezami Ali Akbar 
Published: August 2014

AbstractPolymer actuators have received much attention due to their vast potential applications. In this work the preparation of polyaniline nanocomposite actuator is studied. The main objective is to overcome the disadvantages of pristine polyaniline in thermal, mechanical and electroactive properties. Montmorillonite is the best candidate for this purpose. Various polyaniline/modified montmorillonite nanocomposite films were prepared using solution method. The properties of nanocomposites are characterized by X-ray diffractometry, transmission electron microscopy, thermal gravimetric analysis, dynamic mechanical analysis, conductivity measurement and cyclic voltammeter. The effects of actuator length and applied scan rate as well as the response of applied potential in actuating applications were investigated. The results show that the structure of nanocomposite is exfoliated. Adding organoclay to polyaniline matrix regardless of decreasing its conductivity; increases the stiffness of the actuator resulting in lower bending level in a linear manner. It reduces the required time to reach the maximum bending, also recovery bending time, i.e. actuator response. Increasing the applied scan rate decreases the actuator bending. Also increasing the length of actuator increases the amount of nanocomposite actuator bending in a linear manner.
Static light scattering and transmission microscopy study of dilute Nafion solutions
Authors: Wen-Hong Liu , Ting-Yi Yu , Yu T. Leon , Hsiu-Li Lin 
Published: August 2014

AbstractNafion, an ionomer composed of perfluorocarbon backbone and vinyl ether side chains terminated with -SO3 - groups, has dual solubility parameters, i.e. δ1= 9.7 (cal/cm3)1/2 relating to perfluorocarbon backbones and δ2 = 17.3 (cal/cm3)1/2 relating to sulfonated vinyl ether side chains. It had been reported that Nafion molecules aggregated in dilute and semi-dilute water and alcohol solutions. In this study, we report static light scattering (SLS) measurements of dilute Nafion in N,N’- dimethyl formamide (DMF, solubility parameter δ =12.2 (cal/cm3)1/2, dielectric constant ε=36.7) and N,N’-dimethyl acetamide (DMAc, δ =10.8 (cal/cm3)1/2, ε=37.8) solutions with Nafion concentrations ranging from 0.2 mg/ml to 1.0 mg/ml. The DMF and DMAc solvents have δ closing to δ1 of Nafion perfluorocarbon backbones and ε much lower than water (ε =78). Thus DMF and DMAc are compatible with Nafion perfluorocarbon and few Nafion molecules aggregate in DMF and DMAc solvents when [Nafion]< 1.0 mg/ml. The lower ε of DMF and DMAc led to low polyelectrolyte effect of Nafion in these two solvents. The obtained Mws of present work were in good agreement with the Mw obtained from Nafion in dilute dimethyl sulfoxide (DMSO, δ =12.0 (cal/cm3)1/2, ε=46.6) solutions, reported by Lousenberg, using size exclusion chromatography incorporating static light scattering detection. The <RG> data obtained from SLS measurements were compared with the particles sizes of transmission electron microscope (TEM) observations of freeze dried Nafion thin films prepared on copper grids with 0.6 mg/ml Nafion solutions. Comparable results were obtained from these two observations.
Conductivity and Thermal Analysis Studies of Solid Polymeric Electrolytes Based on Plasticized Hydroxyethyl Cellulose
Authors: Machado Gilmara O. , Prud’homme Robert E. , Pawlicka Agnieszka 
Published: August 2014

AbstractTransparent film samples of hydroxyethyl cellulose (HEC) based on solid polymeric electrolytes (SPE) were prepared by the plasticization of HEC with glycerol and addition of lithium perchlorate salt. SPEs with different quantities of glycerol and LiClO4 were studied by electrochemical impedance spectroscopy (EIS), Dynamic Mechanical Thermal Analysis (DMTA), TGA (Thermogravimetric Analysis) and DSC (Differential Scanning Calorimetry). The ionic conductivity measurements revealed that the sample containing [O]/[Li]=8 and 48% of glycerol showed the conductivity value of almost 10-4 S/cm at room temperature. The TGA analysis of electrolytes with high plastizant and salt concentrations showed 25% weight loss after heating to 130 °C, which can be related to the liberation of absorbed water. Finally, DMTA measurements showed changes attributed to the glass transition (Tg) evidenced by the decrease in the elastic modulus value and peaks in the tanδ curves. These results demonstrated that HEC is a good material to be used as a matrix for new solid polymeric electrolytes.
Molecularly Imprinted Polymers for Selective Adsorption of Cholesterol from Aqueous Environment
Authors: Puoci Francesco , Iemma Francesca , Cirillo Giuseppe , Trombino Sonia , Cassano Roberta , Picci Nevio 
Published: August 2014

AbstractIn this work the preparation and evaluation of molecularly imprinted polymers (MIPs) based on 2-hydroxyethylmetacrylate (HEMA) for selective recovery of cholesterol from aqueous media are reported. HEMA was used as functional monomer in order to maximize the hydrogen bond forming both in prepolymerization complex and in rebinding experiments which were performed in polar solvents; in particular, an acetonitrile:water (7:3 v/v) mixture was employed. The templating effect is clearly seen in the capacity of the synthesized polymers to bind cholesterol, and their selectivity was evaluated using two steroids quite similar to cholesterol such as progesterone and hydrocortisone which are less effectively bound by the matrices.
Polypropylene/Waste Ground Rubber Tire Powder Foams: A Study of the Relationship Between Processing and Structure Using Supercritical Carbon Dioxide
Authors: Zhang Zhen Xiu , Zhang Shu Ling , Xin Zhen Xiang , Kim Jin Kuk 
Published: August 2014

AbstractIn this study, processing-structure relationships in polypropylene (PP)/waste ground rubber tire powder (WGRT) foams made using supercritical carbon dioxide as a physical blowing agent were investigated. In order to investigate the relationship between structure and properties of PP/WGRT foams, it was necessary to make samples with a wide range of controlled structures. For this reason, a systematic investigation of the relationship between processing conditions and structure was performed based on a statistical experimental design. Regression analysis was conducted on the data and expressions were developed to quantify the relationships between structural parameters and processing conditions. The samples were saturated with carbon dioxide at high temperature and high pressure and the saturated specimens were expanded during the pressure-quench process. The importance of the individual processing parameters was determined. Statistical analysis of data showed that saturation temperature was the most important factor determining cell size, cell density and relative density. By controlling the foaming conditions, PP/WGRT samples having the same foam density and different cell size or having the same cell size and different foam density were produced.
Radical copolymerization of styrene and acrylonitrile in the presence of oligooxyethylene azoester
Authors: Wiśniewska Ewa , Pabin–Szafko Barbara 
Published: August 2014

AbstractTelechelic vinyl oligomers terminated with hydroxyl groups were prepared by free radical copolymerization of styrene (S) and acrylonitrile (AN), initiated by azoester-2,2’-azobis[2-methyl-ω-hydroxy-oligo(oxyethylene) propionate] [AIB-OOE(400)], carried out in N,N-dimethylformamide. The reactivity ratios rS=0,225 and rAN=0,722 for styrene and acrylonitrile, respectively, were evaluated by Kelen-Tüdős method. The glass transition temperatures (Tg) of the copolymers were determined by differential scanning calorimetry. Tg values varied with the copolymer composition in the range of 60-82 °C and the maximum Tg value was obtained for copolymer with 60 mol% AN.