bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of glycolysis of poly(ethylene terephthalate) melts
Authors: Campanelli J. R. , Kamal M. R. , Cooper D. G. 
Published: April 2003

AbstractThe reaction of poly(ethylene terephthalate) (PET) melts with ethylene glycol was examined in a pressure reactor at temperatures above 245°C. The reaction rate was found to depend on temperature and on the concentrations of liquid ethylene glycol and of ethylene diester groups in the polymer. A kinetic model proposed for the initial period of the reaction was found to be consistent with experimental data. It was found that internal catalysis by ethylene glycol does not play an important role in the glycolytic depolymerization of PET. The rate constants for glycolysis were calculated for three different temperatures, yielding an activation energy of 92 kJ/mol. Zinc salts, which have a catalytic effect on glycolysis of PET below 245°C, do not appear to influence glycolysis rates above that temperature. © 1994 John Wiley & Sons, Inc.
Preparation of ultrafine metal particles supported on alumina by pyrolysis of polymer complex/alumina composites
Authors: Tamai Hisashi , Sakurai Hiroyuki , Yamagiri Takayuki , Nishiyama Fumitaka , Sakai Hiroshi , Yasuda Hajime 
Published: April 2003

AbstractUltrafine metal particles supported on alumina were prepared by pyrolysis of poly(vinylferrocene) (Poly(VFc))/alumina or sodium polyacrylate‐Pd(II) (Poly(AANa)‐Pd(II))/alumina precursors at 800 ∼ 1200°C. α‐Fe particles produced on k‐Al2O3 was obtained by pyrolysis of the mixture of Poly(VFc)/alumina(5/5) at 1000°C. Crystalline Pd supported on alumina was also obtained from Poly(AANa)‐Pd(II)/alumina precursor. The size of metal particles formed increased with increasing mixing ratio of polymer complex with alumina. © 1994 John Wiley & Sons, Inc.
Phase behavior of poly(ether urethane)‐nylon 6 block copolymer
Authors: Seo Seung Won , Ha Wan Shik 
Published: April 2003

AbstractPoly(ether urethane) (PEU)‐Nylon 6 block copolymer film prepared via melt pressing and subsequent quenching in liquid nitrogen exhibited a one‐phase structure due to the specific interaction between urethane groups in the PEU block and the amide groups in Nylon 6 block through hydrogen bonding. Contrary to this, the solvent cast film showed a microphase separated structure which had risen from the poor solubility characteristics of the PEU block in the solvent. However, by heat treatment, the mutual miscibility of the block copolymer increased as a result of the hydrogen bonding formation. The block copolymer and Nylon 6 binary blend showed that these two polymers are compatible over the entire composition range mainly due to the specific interactions between the urethane and the amide groups in the blend through hydrogen bonding. The block copolymer in the ternary blend which consists of polyrethane (PU), Nylon 6, and the block copolymer prepared by melt extrusion was soluble in either of the PU and Nylon 6 homopolymers, inducing a homogenizing effect. © 1994 John Wiley & Sons, Inc.
pH effects on the solubility of polyacrylamides in hard brines
Authors: Albonico Paola , Lockhart Thomas P. 
Published: April 2003

AbstractSolubility tests have been conducted on hydrolyzed polyacrylamide (PAAm) polymers to define the pH range for solubility as a function of the salinity of the solutions. These tests show for the first time that pH is a critical variable determining the solubility of extensively hydrolyzed PAAm in brines containing divalent cations. The pH range for solubility of PAAm and an acrylamide copolymer as a function of aging in synthetic seawater at elevated temperature is also reported. The underlying mechanisms for the pH‐dependent solubility behavior observed and the implications for petroleum applications of acrylamide polymers are discussed. © 1995 John Wiley & Sons, Inc.
Polymer networks based on the diepoxide–diisocyanate reaction catalyzed by tertiary amines
Authors: Galante María J. , Williams Roberto J. J. 
Published: April 2003

AbstractReactions taking place in a system consisting of a diepoxide (DGEBA, diglycidylether of bisphenol A) and a diisocyanate (TDI 80 : 20, toluene diisocyanate), catalyzed by a tertiary amine (BDMA, benzyldimethylamine), were followed by differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), and chemical titration of isocyanate groups in the pre‐gel stage. It was found that the main reactions took place in series, in steps of increasing temperature: (i) isocyanurate formation, (ii) epoxy‐isocyanate reaction leading to oxazolidone rings, and (iii) isocyanurate decomposition by epoxy groups producing oxazolidone rings. Isocyanurate rings were stable in the presence of epoxides and an isocyanate excess [reaction (ii) was faster than (iii)]. Epoxy homopolymerization (secondary reaction) occurred in parallel with steps (ii) and (iii). Step (i) took place by two different mechanisms and led to a maximum conversion, possibly limited by topological restrictions. A kinetic study of TDI trimerization in the presence of an equimolar amount of DGEBA and variable amounts of BDMA led to a third‐order regression with an activation energy E = 43 kJ/mol. © 1995 John Wiley & Sons, Inc.
Morphologies of poly(vinylcarbazole)–polyisoprene graft copolymer and blend
Authors: Ishikawa Satoshi 
Published: April 2003

AbstractThe microstructures of a poly(vinylcarbazole‐g‐isoprene) and blend of poly(vinylcarbazole) (PVCz) and polyisoprene (PIP) were studied by transmission electron microscopy (TEM). In the graft copolymer, the unique microphase separated structure was observed. In the blend, the blend ratio did not correspond to the area ratio on the TEM photograph. It is suggested that the results are caused by rigid and crystalline PVCz and low glass‐transition temperature of PIP. © 1995 John Wiley & Sons, Inc.
Mechanical behavior of particulate composites: Experiments and micromechanical predictions
Authors: Wong F. C. , Ait‐Kadi A. 
Published: April 2003

AbstractA model, based on linear elasticity and the first law of thermodynamics, was evaluated using experimentally derived data to verify its predictive capabilities. The model demonstrated that it could correctly predict the mechanical behavior of highly loaded composites if a representative adhesion energy was available. It worked well for systems where material nonlinearity was mainly due to particle debonding. The model could not, however, account for the effects of localized straining or stress concentrations on composite modulus or strength. In systems where matrix nonlinearity dominated, predictinos were less satisfactory. Although the model oversimplified the debonding process, it provided a convenient mechanism for relating the composite modulus and stress–strain state to the loss of reinforcement without requiring a micromechanical description that was too cumbersome to manage. Nevertheless, the inability of the model to account for localized strains, stress concentrations, and matrix nonlinearity needs to be addressed in order to obtain better mechanical behavior predictions. © 1995 John Wiley & Sons, Inc.
Graft copolymerization of dimethylacrylamide onto AFLAS
Authors: Lopez Rafael , Sanchez Victor , Fucugauchi Luz Alicia , Otsuhata Kazushige 
Published: April 2003

AbstractThe method of irradiation grafting of DMAA onto AFLAS (alternating copolymer of tetrafluoroethylene and propylene) films was studied. The effect of the solvent on the grafting yield was determined. As a result, it might be important to evaluate the blood compatibility of the films already grafted by using an in vitro test. Benzene tests seem to be the most adequate for copolymerization. Grafting yield was better in the monomer 40–60% concentration range. The degree of grafting increases proportionally to does rate in gamma ray radiation. The graft copolymerization is terminated via unimolecular mechanism. © 1995 John Wiley & Sons, Inc.
Effects of poly(vinyl acetate) and poly(methyl methacrylate) low‐profile additives on the curing of unsaturated polyester resins. II. Morphological changes during cure
Authors: Huang Yan‐Jyi , Su Chin‐Cheng 
Published: April 2003

AbstractThe effects of two low‐profile additives (LPA), poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA), on the morphological changes during the cure of unsaturated polyester (UP) resins at 110°C were investigated by an approach of integrated reaction kinetics‐morphology‐phase separation measurements by using a differential scanning calorimeter (DSC), scanning electron microscopy (SEM), optical microscopy (OM), and a low‐angle laser light‐scattering appartus (LALLS). For the UP resins cured at 110°C, adding LPA could facilitate the phase separation between LPA and crosslinked UP phases early in the reaction, and discrete microgel particles were thus allowed to be identified throughout the reaction. Microvoids and microcracks responsible for the volume shrinkage control could also be observed evidently at the later stage of reaction under SEM. Depending on the types of LPA and the initial molar ratios of styrene to polyester CC bonds, the morphological changes during the cure varied considerably. The progress of microstructure formation during reaction has been presented. Static ternary phase characteristics for the styrene–UP–LPA system at 25°C have also been employed to elucidate the resulting morphology during the cure in both the continuous and the dispersed phases. © 1995 John Wiley & Sons, Inc.
Assimilation of oil from metal surfaces by epoxy adhesives: XPS and ATR analyses
Authors: Hong S. G. , Boerio F. J. 
Published: April 2003

AbstractThe oil displaceing and absorbing behaviors of epoxy adhesives cured with amidoamine curing agents on oiled metal substrates were studied using X‐ray photoelectron spectroscopy (XPS) and attenuated total reflection infrared spectroscopy (ATR). A Simple XPS experiment demonstrated that amidoamine curing agents could displace an aliphatic oil from the cold‐rolled steel (CRS) and the electrogalvanized steel (EGS) surfaces, but an epoxy resin based on bisphenol A could not. Results of ATR measurements sowed that the oil was effectively displaced from the CRS surface and absorbed as deep as 2 μm into the epoxy adhesive cured with amidoamine with low amine numbers. But the oil was mostly present in the 0.3 μm thick adhesive layer near the CRS/adhesive interface for the epoxy adhesive cured with amidoamine with high amine numbers. The oil absorbing ability of the adhesive was worse on the oiled EGS substrate than on the oiled CRS substrate. It was also found that the pressure applied during cure could greatly facilitate the absorption of oil into the adhesive. © 1995 John Wiley & Sons, Inc.
Anomalous diffusion of iodine ions into polypropylene implanted with F+ and I+ ions
Authors: Hnatowicz Vladimír , Kvítek J. , S̆vorc̆ík Václav , Rybka Vladimír , Popok Vladimír 
Published: April 2003

AbstractThe diffusion of K and I atoms from 5 M water solution of KI into polypropylene implanted with 150 keV F+ and I+ was studied at boiling temperature. Standard Rutherford back scattering (RSB) technique was used for the determination of concentration depth profiles of diffused atoms. It was found that the I and K atoms penetrate the polymer surface layer affected by ion implantation and they are captured by trapping centers produced by electronic energy losses of implanted ions. The uptake of K atoms is several times higher than that of I atoms, and the relative K concentration exceeds the KI stoichiometric value. © 1995 John Wiley & Sons, Inc.
One‐stage method of preparing core–shell particles
Authors: He W. , Tong J. , Wang M. , Pan C. , Zhu Q. 
Published: April 2003

AbstractA one‐stage method of preparing code–shell particles was developed for the system containing silicone oils and glycidle methacrylate (GMA). Although the formation of core–shell particles for the systems containing silicone oils and methyl methacrylate (MMA) or styrene (ST) is possible in view of thermodynamics, the core–shell particles were not obtained. Factors such as better compatibility of silicone oils with vinyl monomers, higher swelling degree of silicone rubber in the vinyl monomers, and larger addition rate of thevinyl monomers with Si—H during the crosslinking of silicone oil containing vinyl group and Si—H (SVB and SHB) do not favor the formation of core–shell particles. X‐ray photoelectron spectrometer (ESCA) was used in determining the formation of core–shell particles. The mechanism of the formation of core–shell particles is discussed. © 1995 John Wiley & Sons, Inc.
Effect of the Sb2O3 catalyst on the solid‐state postpolycondensation of poly(ethylene terephthalate)
Authors: Kokkalas Demetris E. , Bikiaris Demetris N. , Karayannidis George P. 
Published: April 2003

AbstractThe effect of Sb2O3, which is used as the main catalyst in the production of poly(ethylene terephthalate) (PET) by melt polymerization, was studied on solid‐state postpolycondensation. It was observed that the catalyst works efficiently even in the solid state. The number‐average molecular weight of a PET prepolymer with an Sb2O3 content of 2000 ppm was increased from 18,350 to 40,800 after heating at 210°C for 8 h under vacuum (2–3 Pa), whereas when the catalyst was absent, the molecular weight of the same prepolymer under the same conditions was just increased to 22,500. The activation energies and the frequency factors of the esterification and ester interchange reactions, which take place simultaneously during solid‐state postpolycondensation, were determined. © 1995 John Wiley & Sons, Inc.
Immobilization of β‐galactosidase onto polymeric supports
Authors: Rejikumar S. , Devi Surekha 
Published: April 2003

AbstractPoly(vinyl alcohol) cross‐linked with para‐formaldehyde (PVA–F) and natural polysaccharide–chitosan in bead form and salicylic acid–resorcinol–formaldehyde polymeric resin (SRF) in powder form were used for immobilization of β‐galactosidase through covalent linkages. Various activation processes and conditions were optimized. Immobilized enzyme showed very good storage stability at room temperature. Durability of the enzyme was also improved on immobilization. On repeated use of enzyme immobilized on chitosan beads, no loss was observed in enzyme activity even after 10 batches. Michaelis constant Km and maximum reaction velocity Vm were calculated for free and immobilized enzyme systems. Effect of pH and temperature on enzyme activity was estimated and energy of activation (Ea) and inactivation constant (Ki) for free and immobilized enzyme were calculated. © 1995 John Wiley & Sons, Inc.
Use of carbon fibril additives to reduce the dc resistivity of elastomer‐based composites
Authors: Farriss C. W. , Kelley F. N. , Von Meerwall E. 
Published: April 2003

AbstractWe have prepared insert model solid rocket propellants of two kinds, polycaprolactone (PCP) networks highly (60%) plasticized with triacetin and hydroxyl‐terminated polybutadiene (HTPB) cross‐linked with isophorone diisocyanate, both filled with over 65% NaSO4 and Al powders as well as traces of fine carbon fibrils 100 Å thick and several micrometers long. Sheets of these dieletric composites were used for dc surface and volume electrical resistivities near room temperature. Addition of less than 1% fibrils in the PCP composites reduces volume resistivity by a factor of 10. The amount required for HTPB is only 0.1% leaving processability unaffected; resistivity reduction rises from one to nearly four orders of magnitude as potential differnce in increased from 10 to 500 V. Addition of fibrils to HTPB composites is a promising candidate for minimizing the incidence of dangerous electric discharge events. © 1995 John Wiley & Sons, Inc.
Determination of interfacial tension between PA/PP and LCP/PP by IFR method and effect of compatibilization on interfacial tension
Authors: Kirjava J. , Rundqvist T. , Holsti‐Miettinen R. , Heino M. , Vainio T. 
Published: April 2003

AbstractThe dynamic imbedded fiber retraction (IFR) method was used to measure the interfacial tension between two molten polymers. The aim was to evaluate the applicability of this method for polypropylene (PP) used as matrix, and two polyamide (PA6, PA66) and thermotropic main‐chain liquid crystalline polymer fibers. The effect on the interfacial properties of modifying the PP matrix with compatibilizers was studied as well. The IFR method was found to be suitable for evaluating the interfacial properties of these polymer blends. The measured interfacial tensions correlated well with the morphology and mechanical properties of the blends and values calculated from the harmonic mean equation. Although the measured interfacial tensions were generally lower than the theoretical ones, the order of the values for the different polymer pairs was similar. © 1995 John Wiley & Sons, Inc.
Characterization of coatings of poly(hexamethylene adipamide) deposited on carbon fibers by interfacial polymerization techniques
Authors: Varelidis P. C. , Skourlis T. P. , Bletsos J. V. , McCullough R. L. , Papaspyrides C. D. 
Published: April 2003

AbstractPolyamide coatings deposited on carbon fibers by means of an interfacial in situ polymerization technique have been examined. Two different coating processes were used, depending on the length of the carbon fibers (short or long). The effect of the concentration of the monomer reactants on the quantity of coating deposited on the fibers has been determined using thermogravimetric analysis (TGA). Characterization techniques used to identify the nature of the coating process product included Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). Using the above techniques, IR spectra were collected and identified, and important polymer properties, such as morphology, melting point, and the molecular weight of the polymer coating were determined. © 1995 John Wiley & Sons, Inc.
Graft copolymerization of N‐vinylpyrrolidone onto gelatin
Authors: Gao Jian‐Ping , Li Zhi‐Chong , Huang Ming‐Zhi 
Published: April 2003

AbstractThe graft copolymerization of N‐vinylpyrrolidone (VP) onto gelatin in aqueous medium, with α,α′‐azobisisobutylonitrile as initiator, has been studied. The effects of various reaction parameters such as temperature, reaction time, as well as the concentrations of initiator, monomer, and gelatin on the percentage of grafting and grafting efficiency were also studied. The chain‐transfer constant of isopropanol in this system was calculated. Finally, the grafted samples were analyzed with IR, DSC, TEM, and SEM measurements. © 1995 John Wiley & Sons, Inc.
Improvement of hot water resistance of poly(vinyl alcohol) hydrogel by acetalization and irradiation techniques
Authors: Darwis Darmawan , Yoshii Fumio , Makuuchi Keizo , Razzak Mirzan T. 
Published: April 2003

AbstractIn order to improve the heat stability of poly(vinyl alcohol) (PVA) hydrogel, acetalized PVA was irradiated with electron beam irradiation. The acetalization was strongly affected by PVA water content. There is an optimum water content of 20–30% for acetalization of PVA. The PVA gave maximum tensile strength at a dose of 100 kGy before or after acetalization. The PVA hydrogel maintained tensile strength of 10 MPa, even after 90 min boiling (98°C) in water or autoclave sterilization (121°C). It was confirmed that irradiation after, or before, acetalization is effective for enhancing heat resistance of a PVA hydrogel. The hydrogel is transparent, soft, has high tensile strength, and high hot water resistance. © 1995 John Wiley & Sons, Inc.
Bending behavior of gelatin/poly(hydroxyethyl methacrylate) IPN hydrogel under electric stimulus
Authors: Ma Ji Tao , Liu Ling Rong , Yang Xian Jin , De Yao Kang 
Published: April 2003

AbstractThis article deals with an interpenetrating polymer network composed of crosslinked gelatin (Gel) with glutaraldehyde (GA) and poly(hydroxyethyl methacrylate) (PHEMA) crosslinked with N,N′‐methylene bisacrylamide (BisAm). The hydrogel network is able to bend under an electric field stimulus. The composition of the interpenetrating polymer network (PN), pH, ionic strength, and voltage can influence the degree of bending. The mechanism of the electromechanichemical (EMC) effect is discussed as well. © 1995 John Wiley & Sons, Inc.
Hydrolytic thermal degradation of poly(naphthoyleneimide benzimidazole) in concentrated sulfuric acid
Authors: Lavrenko P. N. , Okatova O. V. 
Published: April 2003

AbstractTranslational diffusion in 96% H2SO4 and intrinsic viscosity of poly(naphthoyleneimide benzimidazole) (PNIB) have been investigated in different stages of its degradation in solution in the temperature range from 65 to 120°C. The degradation rate constant k has been determined from the change in molecular weight M of degraded products with time at the fixed temperature of solution. The activation energy of the process E was calculated from the temperature dependence of k. The difference in E values at low and high temperatures was found. At degradation temperatures above 90°C, the activation energy of hydrolysis was obtained as E = 133 kJ/mol, which coincides with that of aromatic polyamides in sulfuric acid. The data obtained are compared with the results of the investigations of optical properties of products of PNIB degradation in solution and PNIB stability in the solid state. An explanation of anomalies observed during PNIB degradation at low temperatures is suggested. © 1995 John Wiley & Sons, Inc.
Biodegradable polyester blends for biomedical application
Authors: Zhang Lianlai , Xiong Chengdong , Deng Xianmo 
Published: April 2003

AbstractA new family of bioabsorbable materials suitable for biomedical applications was designed and prepared by means of blending of some available polyesters to develop new biodegradable materials tailored for different requirements. Multiphase polymer blends containing poly(d, l‐lactide) (PLA), poly(ε‐caprolactone) (PCL), poly(d, l)‐lactide‐co‐poly(ethylene glycol) (PELA), poly(ε‐caprolactone) ‐co‐poly(ethylene glycol) (PECL), and poly(ß‐hydroxybutyrate) (PHB), PLA/PCL, PELA/PECL, PHB/PLA, PHB/PELA, PHB/PCL, and PHB/PECL blends were respectively investigated. It was found that PLA/PCL, PHB, and PHB/PLA and PHB/PCL blends were seemingly immiscible, with their morphology and hydrolytic behavior were determined by the composition of the blends. On the other hand, the miscibility of PELA/PECL, PHB/PELA, and PHB/PECL blends was improved by using PELA and/or PECL block copolymers that contained poly(ethylene glycol) (PEG) as compatibilizer. The blends showed to a certain extent miscibility, fine phase morphology, and fast hydrolysis. © 1995 John Wiley & Sons, Inc.
Miscibility and peel strength of acrylic pressure‐sensitive adhesives: Acrylic copolymer–tackifier resin systems
Authors: Kim Hyun‐Joong , Mizumachi Hiroshi 
Published: April 2003

AbstractInfluence of miscibility between the components in acrylic pressure‐sensitive adhesives upon their peel strength P as a function of temperature has been studied. In case of miscible blend systems, incorporation of tackifier resins into the pressure‐sensitive adhesive systems results in the modification of the bulk properties, including Tg, and a plot of P against ΔT gives a smooth master curve, where ΔT is defined as the difference between the temperature of peel test and Tg of the blend. However, in case of immiscible blends where two phases exist in the system, no master curve can be obtained, and P of an acrylic copolymer decreases as the tackifier content increases. In this case, physical properties and adhesive performance will be governed by a matrix phase, and a dispersed phase will act as a filler. © 1995 John Wiley & Sons, Inc.