bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of doping treatment on gas transport properties and on separation factors of polyaniline memebranes
Authors: Rebattet L. , Escoubes M. , Genies E. , Pineri M. 
Published: April 2003

AbstractGas permeation experiments of H2, O2, CO2, N2, and CH2 were carried out with freestanding films of the conjugated polymer polyaniline (PANi). At first annealed to remove residual solvent, PANi membranes were doped (i.e., protonated) in a strongly acidic medium (HCl 4M), undoped in a basic medium (NH4OH 1M), and redoped in a slightly acidic medium (HCl 10−2M). Protonation and deprotonation kinetics were studied by elementary analysis Gas permeation experiments were performed with the annealed, doped, undoped, and redoped PANi films. The gas transport mechanism was clearly influenced by the diffusivity factor and it obeyed a Fickian diffusion model. From the variations in permeability coefficients with the doping treatment, gases could be divided in two subgroups comprising H2, O2, and CO2 on one hand and N2 and CH4 on the other. After the doping–undoping–redoping process, gas fluxes were increased by 15% for the smaller gases and were decreased by 45% for the larger gases. As a consequence gas separation factors were approximately doubled for a gas pair involving the two subgroups and these were unchanged for a gas pair involving only one subgroup. The highest O2/N2 and CO2/CH4 selectivity coefficients were, respectively, equal to 14 and 78. © 1995 John Wiley & Sons, Inc.
Microstructure, deformation, and fracture behavior of commercial ABS resins
Authors: Bernal Celina R. , Frontini Patricia M. , Sforza Miguel , Bibbó Miguel A. 
Published: April 2003

AbstractThe microstructure, deformation, and fracture behavior of commercial ABS resins were investigated. Fracture mechanics studies were carried out under both static and dynamic conditions. Fracture toughness was evaluated via the J‐integral analysis. In addition static fracture experiments were conducted at different temperatures. The ABS resins assayed here exhibited different deformation and fracture behavior depending on loading mode, matrix molecular weight, strain rate, temperature, rubber content, and morphologies. The reasons for this material's behavior are discussed with the help of scanning and transmission electron microscopy (SEM and TEM) investigation methods. The major source of toughness seems to be matrix crazing and rubber cavitation under both static and dynamic experiences, but at low strain rates shear yielding also contributes to toughening. © 1995 John Wiley & Sons, Inc.
Emulsifier‐free synthesis of monodisperse core–shell polymer colloids containing chloromethyl groups
Authors: Bon Stefan A. F. , Van Beek Henno , Piet Pieter , German Anton L. 
Published: April 2003

AbstractBoth the synthesis of m,p‐trimethyl(vinylbenzyl) ammonium chloride (TMVBAC) and the synthesis of polymer colloids consisting of a shell of poly(vinylbenzyl chloride) grafted onto a well‐defined, monodisperse poly(styrene–divinylbenzene) core are described. The preparation of the polymer latices consists of a sequence of different emulsifier‐free emulsion polymerizations. First, monodisperse poly(styrene–divinylbenzene) seed latices, with 2,2′‐azobis(2‐amidinopropane) hydrochloride (AIBA·2HCl) as cationic initiator, are prepared under batch conditions. These latices are used for the seeded polymerization of divinylbenzene (DVB), in order to synthesize monodisperse particles, with a well‐defined spherical shape, which contain a sufficient amount of pendant vinyl groups for grafting of the vinylbenzyl chloride (VBC) monomer. After the graft polymerization, the chloromethyl groups can easily be modified with a postpolymerization reaction. As an example, the amination with trimethylamine (TMA) is described. © 1995 John Wiley & Sons, Inc.
Degradable property of UV‐cured Hessian cloth (jute)
Authors: Khan Mubarak A. , Uddin M. Khabir , Islam M. Nurul , Ali K. M. Idriss 
Published: April 2003

AbstractTwelve different formulations were developed with urethane acrylate oligomer in combination with a number of functional monomers in the presence of different additives, fillers, and plasticizers. Hessian cloth (jute product) was coated with these formulated solutions and cured under UV radiation. Enhancement of tensile strength and elongation was determined. Loss of these properties due to simulating weathering was also measured. The treated Hessian cloths were buried in soil, water, and mud for a long period and it was found that the samples put in mud were completely degradable while those treated in water and soil retained their tensile properties. © 1995 John Wiley & Sons, Inc.
Preparation and characterization of crosslinked gelatin microspheres
Authors: Akin H. , Hasirci N. 
Published: April 2003

AbstractGelatin, a natural macromolecule, is widely used in biomedical and biotechnological applications and is a good candidate for preparation of microspheres and microcapsules for the purpose of controlled release applications of drugs. In this study, gelatin microspheres crosslinked with glutaraldehyde with different crosslink densities were prepared by the phase separation technique induced by temperature change. The chemical structures of the microspheres were examined with FTIR and formation of crosslinks were observed. Topography, size, and shape of the microspheres were examined with scanning electron microscopy (SEM) and a narrow size distribution (approximately 1 μm) was observed. Thermal properties of microspheres were analyzed by differential scanning calorimetry and an increase in glass transition temperature values with an increase in crosslinking was observed. For each sample, dry and swollen densities of microspheres were determined by pycnometric methods and the average molecular weights between the crosslinks, Mc, were calculated from the equilibrium swelling experiments using the modified Flory‐Rehner thermodynamic theory. A decrease in percent solvent content values with decreasing average molecular weight between the crosslinks was observed. © 1995 John Wiley & Sons, Inc.
Melt blending of linear low‐density polyethylene and polystyrene in a haake internal mixer. I. Compatibilization and morphology development
Authors: Yang Li‐Ying , Smith Theodore G. , Bigio David 
Published: April 2003

AbstractMorphology development was investigated during blending of linear low‐density polyethylene (LLDPE) and polystyrene (PS) (the minor phase) in a Haake internal mixer. In addition, the blending was studied using 5 wt % Kraton styrene–ethylene/propylene (SEP) diblock or styrene–ethylene/butylene–styrene (SEBS) triblock copolymers as compatibilizing agents. Scanning electron microscopy (SEM) examinations of blends show a bimodal particle size distribution of the minor phase during the initial stage of morphological development. Morphology observations suggest that the main function of the compatibilizer during blending lies in reducing the interfacial tension between two immiscible polymer phases. The addition of the copolymer reduces the average domain size from a micron to a submicron range. Compatibilization mechanisms of the copolymers with the immiscible blends are proposed. The superiority of SEBS triblock over SEP diblock as a stabilizer of the morphology was shown. © 1995 John Wiley & Sons, Inc.
Internal pressures and thermal pressure coefficients for solid polymers
Authors: Seo Myung Po , Shin Boo Young , Han Do Hung , Cho Bongkee 
Published: April 2003

AbstractThe temperature and pressure dependence of the thermal pressure coefficient and internal pressure for eight polymer solids are calculated. The principal results are as follows: (1) The pressure dependence of the thermal pressure coefficient at constant temperature is relatively small. (2) For some solid polymers, as a function of temperature, a maximum in the thermal pressure coefficient is predicted in the solid region, and the temperatures corresponding to the maximum values are estimated. (3) For most solid polymers, the zeropressure internal pressure increases with increasing temperature over the entire temperature range to the glass transition temperature or the melting point. © 1995 John Wiley & Sons, Inc.
Synthesis and application of core–shell particles as toughening agents for epoxies
Authors: Qian Julie Y. , Pearson Raymond A. , Dimonie Victoria L. , El‐Aasser Mohamed S. 
Published: April 2003

AbstractPoly(butadiene‐co‐styrene) [P(B‐S)] core‐poly(methyl methacrylate) (PMMA) shell particles were prepared using a two‐step emulsion polymerization. These core‐shell particles were used to toughen an epoxy polymer. The role of particle‐epoxy interfaces were studied by systematically varying the shell compositions of the core‐shell particles such as PMMA, P[MMA‐acrylonitrile (AN)], P[MMA‐glycidyl methacrylate (GMA)] and P[MMA‐divinyl benzene(DVB)]. Therefore, the nature of the particle‐epoxy interfaces is varied in terms of physical interactions and chemical bonding. The fracture toughness values of the toughened epoxies were measured using linear elastic fracture mechanics. Results indicate that the morphology of the dispersed particles in the epoxy matrix plays an important role in the toughening of epoxies. This degree of dispersion can be varied by incorporating AN and GMA comonomers in the PMMA shells or by crosslinking the shell. In summary, nanoscale interactions of the rubber‐matrix interface do not directly influence fracture toughness, instead, it was found that the nanoscale interactions could be used to control the blend morphology which has a dramatic effect on toughness. © 1995 John Wiley & Sons, Inc.
Thermal degradation characteristics of poly[poly(ethylene glycol)] phosphates
Authors: Basu Sudhapada , Chatterjee Nandini , Maiti Mrinal M. 
Published: April 2003

AbstractThermal degradation characteristics of some poly[poly(ethylene glycol)] phosphates (PPEGP) based on ethylene glycol (PEGP), an equimolar mixture of ethylene glycol and trigol (PETP), digol (PDGP), and trigol (PTGP) have been studied by combined differential thermal and thermogravimetric analyses (DTA/TGA). It has been shown that, in spite of their structural similarities, the PPEGPs do not conform to any generalized degradation pattern. Local strains in the crosslinked network and the possible intranetwork topographic interferences due to crossovers, entanglements, and varying lengths of polyoxyethylene link units are believed to play a pivotal role in the thermal degradation of individual PPEGPs. © 1995 John Wiley & Sons, Inc.
Magnetroviscoelastic behavior of composite gels
Authors: Shiga Tohru , Okada Akane , Kurauchi Toshio 
Published: April 2003

AbstractDynamic viscoelasticity of silicone gels having many lines of dispersed iron particles under the influence of external magnetic fields was studied. The particulate composite enhanced its elastic modulus by action of magnetic fields. The magnetroviscoelastic behavior was caused by the cohesive forces between magnetically polarized particles and was analyzed using a simple model of induced dipole‐induced dipole interactions. The presented results provide insight into the relationship between macroscopic viscoelastic behavior of the composite gels and the microscopic bondings between dispersed particles. © 1995 John Wiley & Sons, Inc.
Synthesis and characterization of poly(o‐ethoxyaniline): A processable conducting polymer
Authors: Dhawan S. K. , Trivedi D. C. 
Published: April 2003

AbstractThe synergic effect of the substituentlike ethoxy group on the electronic properties of conducting polyaniline was investigated. The presence of substituents affects not only the electrochemical polymerization window but also brings about changes in optical and electronic properties of the parent polymer polyaniline. The study indicates that electrochemical polymerization of (o‐ethoxyaniline) yields a conducting polymer that shows a multiple color transition (yellow → green) on switching the potential between the reduced and oxidized states with an electrochromic response time of 40 ms in addition to its solubility in dimethyl sulfoxide, N‐methyl pyrrolidinone, etc. However, the chemical polymerization of the monomer yields a crimson red polymer that is less conducting but has solubility in ethanol/methanol. Evaluation of this alcohol soluble polymer as a corrosion inhibitor for iron in acidic medium shows that it offers corrosion inhibition efficiency of 90%. © 1995 John Wiley & Sons, Inc.
Bulk polymerization of hydroxyl terminated polybutadiene (HTPB) with tolylene diisocyanate (TDI): A kinetics study using 13C‐NMR spectroscopy
Authors: Dubois C. , Désilets S. , Ait‐Kadi A. , Tanguy P. 
Published: April 2003

AbstractThe bulk polymerization of hydroxyl‐terminated polybutadene with tolylene diisocyanate has been studied in uncatalyzed isothermal reactions. The conversion in urethane was monitored by 13C‐NMR spectroscopy of the CO function at level up to 70%. Effects of reagents ratio and temperature were investigated. The experimental data were modeled by a set of two competitive second‐order reactions to account for the difference in reactivity of o‐NCO and p‐NCO groups of tolylene 2,4 diisocyanate. The apparent kinetic constants calculated appeared to be statistically higher than previous results found in literature from work in aromatic solvents. Deviations from second‐order law were observed during the last stage of polymerization. Activation energies were estimated at 12.3 kJ. mol−1 and 42.8 kJ. mol−1 for the p‐NCO and o‐NCO groups, respectively. The difference in their reactivity tended to decrease as temperature of reaction was increased. © 1995 John Wiley & Sons, Inc.
Direct synthesis of electrorheological suspension containing salt of poly(methacrylic acid) and its electrorheological effect
Authors: Xie Hong‐Quan , Guan Jian‐Guo , Guo Jun‐Shi 
Published: April 2003

AbstractColloidal suspensions containing salts of poly(methacrylic acid) which exhibit high electrorheological (ER) activity were synthesized by inverse emulsion polymerization. Factors influencing the ER effect were studied. The results showed that maximum yield stress occurred at optimum amounts of both polymeric stabilizer and crosslinking agent used in the inverse emulsion polymerization as well as a certain water content of the particles, while yield stress increased with electric field strength, average diameter of the particles below 0.9 μm, or the molar ratio of the salt to the acid. The ER activity for the suspensions containing different monovalent counter ions decreased in the following order: Li+ > Na+ > K+ > NH4+. The phenomena were discussed with the ionic polarization mechanism. © 1995 John Wiley & Sons, Inc.
Characterization of regenerated silk fibroin membranes for immobilizing glucose oxidase and construction of a tetrathiafulvalene‐mediating glucose sensor
Authors: Yu Tongyin , Liu Haiying , Deng Jiaqi , Liu Yongcheng 
Published: April 2003

AbstractThe IR spectra, the electronic absorption bands, and scanning electron microscopy (SEM) of the blend membranes of regenerated silk fibroin and glucose oxidase were reported for the first time and the second generation of glucose sensor based on glucose oxidase immobilized in the regenerated silk fibroin membrane was first constructed. The IR absorption spectra of the pure regenerated silk fibroin membrane were ascribed to its structural characteristics by which the part transition from silk I to silk II was recognized in ethanol immersion. Those spectra of the blend membrane of regenerated silk fibroin and glucose oxidase were identified as a composite of the absorption bands characteristic of both macromolecules. The electronic absorption bands showed that the glucose oxidase in the membrane exists in aggregates. A sea islands' structure was observed by SEM. These findings suggest that the regenerated silk fibroin and glucose oxidase are incompatible and their molecular interactions are very weak. A tetrathiafulvalene‐mediating glucose sensor, employing immobilization of glucose oxidase by regenerated silk fibroin, was fabricated. The influences of temperature, applied potential, and pH on steady‐state electrocatalytic oxidation of glucose at the sensor were evaluated. The response of the sensor to glucose under N2 saturation reached 95% steady‐state current within 40 s. The sensor could be used repeatedly for 1.5 months without deterioration of the response. © 1995 John Wiley & Sons, Inc.
Novel rolltruded membranes. III. The effect of processing temperature on the gas transport properties of isotactic polypropylene
Authors: Ciora R. J. , Magill J. H. 
Published: April 2003

AbstractThe solubility and diffusivity of CO2, N2, and CH4 in isotactic polypropylene [iPP] thin films produced via rolltrusion solid‐state processing have been studied. Processing temperatures between 50 and 125°C and draw ratios between 1 and ca. 10 are reported. Variations in the transport coefficients and the activation energies, in conjunction with the molecular theory of diffusion of Pace and Datyner,22,23 were used to assess changes in the micromorphology of the polymer due to this unique processing mode. Specifically, it has been found that the formation and destruction of microvoid volume were necessary to account for the large increases in solubility and decreases in the heats of solution. Additionally, changes in the tortuosity of the diffusive pathways—due in part to crystallite orientation and to the formation of impermeable amorphous regions in the microfibrillar morphology—were found to influence the diffusivity significantly. The tortuosity actually decreased in contrast to the behavior obtained for uniaxially drawn films. Based upon these observations, it is suggested that triaxial stresses induced in rolltruded polymer films are responsible for this morphology and its function in polymer membranes. © 1995 John Wiley & Sons, Inc.
Relationship between dynamic response of surface to environmental changes and adhesive property of polyacrylate
Authors: Xu Mei Xuan , Zhang Wen Hua , Xue Pu Xing , Gao Wei , Yao Kang De 
Published: April 2003

AbstractAcrylate copolymer composed of octadecyl acrylate (OA), 2‐ethyl hexyl acrylate (2‐EHA), hydroxythyl acrylate (HEA), and vinyl acetate (VA) was synthesized. The copolymer was used to adhere polyethylene (PE) with T‐type peel, strength 4.4 N/cm. The interfacial characteristics of copolymer and PE were investigated via ATR‐FTIR, transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), and dynamic contact angle (DCA). Results show that apolar moieties of the adhesive enrich on the interface. Moreover, the time dependence of peel strength coincides with that of enrichment in nonpolar moieties on the interface. © 1995 John Wiley & Sons, Inc.
Tetramethylthiuram disulfide and 2‐mercaptobenzothiazole as binary accelerators in sulfur vulcanization. II. Exchange reactions between the accelerators and their zinc salts in the absence of rubber
Authors: Giuliani B. V. M. K. , McGill W. J. 
Published: April 2003

AbstractExchange reactions between tetramethylthiuram disulfide, 2‐mercaptobenzothiazole, and sulfur in the presence of ZnO were studied by heating powdered mixes to vulcanization temperatures at a preprogrammed rate in a DSC. The reaction was stopped at points along the thermal curve and the mixture was analyzed. Sulfide exchange reactions between the accelerators leads to a mixed accelerator and dimethyldithiocarbamic acid that is trapped by ZnO to give the zinc accelerator complex bis(dimethyldithiocarbamato)zinc (II). Exchange also occurs between the accelerators and ligands on both the thiuram and benzothiazole zinc accelerator complexes. Zinc complexes containing ligands of both accelerators were synthesized. These showed little interaction on being heated with sulfur, but on dissolution yielded a spectrum of products similar to that obtained in the other system containing zinc. Reactions to account for changes in the spectrum of products on heating different mixes of these curatives to different temperatures are discussed. © 1995 John Wiley & Sons, Inc.
Studies of rigid poly(vinyl chloride) (PVC) compounds. IV. Fusion characteristics and morphology analyses
Authors: Chen C. H. , Wesson R. D. , Collier J. R. , Lo Y. W. 
Published: April 2003

AbstractPoly(vinyl chloride) (PVC), PVC/chlorinated polyethylene (CPE), PVC/oxidized polyethylene (OPE), and PVC/CPE/OPE compounds were prepared in a Haake torque rheometer at various temperatures, rotor speeds, and totalized torques (TTQ). The fusion characteristics of these PVC compounds (fusion time, fusion torque, and fusion temperature) were studied. Longer fusion time results in higher fusion temperature. Higher fusion temperature results in lower fusion torque. The fusion time of PVC/OPE compounds is the longest among these PVC blends. However, the fusion time of PVC/CPE/OPE compounds is the shortest among these PVC blends. The fusion time of the PVC/CPE/OPE compound is significantly different from those of PVC, PVC/OPE, and PVC/CPE compounds at the medium starting temperature and the medium rotor speed. Scanning electron microscopy (SEM) analyses successfully revealed the surface morphological changes of the fusion of PVC, PVC/OPE, PVC/CPE, and PVC/CPE/OPE compounds. The lubrication mechanisms of these PVC compounds have also been postulated. © 1995 John Wiley & Sons, Inc.
Effects of catalyst acidity and HZSM‐5 channel volume on the catalytic cracking of poly(ethylene)
Authors: Lin Rong , White Robert L. 
Published: April 2003

AbstractThe effects of catalyst acidity and the restricted reaction volume afforded by the HZSM‐5 zeolite structure on the volatile cracking products derived from poly(ethylene) are investigated. The effectiveness of silica‐alumina, HZSM‐5, and sulfated zirconia acid catalysts for poly(ethylene) cracking are compared. When high catalyst to polymer ratios are employed and volatile products are rapidly removed during cracking, the most abundant volatile products generated by poly(ethylene) cracking are propene and isoalkenes. The relative amount of propene produced and the temperatures corresponding to the maximum rate of volatile hydrocarbon production are found to be related to catalyst acidity. The restricted volume inside HZSM‐5 channels facilitates oligomerization and the production of small alkyl aromatics. © 1995 John Wiley & Sons, Inc.
Effect of an acidic comonomer on thermooxidative stabilization of polyacrylonitrile
Authors: Gupta A. K. , Paliwal D. K. , Bajaj P. 
Published: April 2003

AbstractThis paper presents a study of the reactions involved in stabilization of polyacrylonitrile (PAN) through the effect of various experimental variables on the differential scanning calorimetry (DSC) exotherm and thermogravimetric measurements coupled with Fourier transform infrared (FTIR) spectroscopy, i.e., DSC‐FTIR and TG‐FTIR. The experimental variables used were the environment of heat treatment (viz. oxidative and inert) and in corporation of an acidic comonomer (viz. itaconic acid). The essential findings include the broadening of the exotherm in an air atmosphere over that in a nitrogen (i.e., inert) atmosphere. This broadening of the exotherm was further enhanced in the presence of the acidic comonomer. Furthermore, the exotherm revealed a doublet character with greater separation of the peaks in case of the copolymer than the homopolymer. Possible explanations of these observations are discussed. © 1995 John Wiley & Sons, Inc.