bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prevaporation of water/alcohol mixtures through the PVA membranes containing cyclodextrin oligomer
Authors: Yamasaki Akihiro , Ogasawara Keiichi , Mizoguchi Kensaku 
Published: April 2003

AbstractPrevaporation through the PVA membrame containing β‐cyclodextrin oligomer (PVA/CD membrane) was performed for the mixtures of water/ethanol, water/1‐propanol, and water/2‐propanol. At higher alcohol concentrations, the water selectivities were greatly increased by CD for all the mixtures, in the order of 2‐propanol/water>1‐propanol/water>ethanol/water. The water permeation rate was decreased by CD, and the alcohol permeation rate was decreased much more for each mixture. At lower alcohol concentrations, the water selectivity for 1‐propanol/water was slightly increased by CD, and that for 2‐propanol/water was scarcely affeted, whereas that for ethanol/water was greatly increased. The water permeation rate was increased by CD for each mixture, and the relative increases in the water rates for propanols/water were smaller than that for ethanol/water. The permeation rate of 1‐propanol as well as that of ethanol was decreased by CD, but the rate of 2‐propanol was was increased. These effects of CD can be explained in terms of the inclusion strength. © 1994 John Wiley & Sons, Inc.
Characterization of polyamide 6 made by reactive extrusion. II. Analysis of microstructure
Authors: Hornsby P. R. , Tung J. F. 
Published: April 2003

AbstractConsideration is given to the characterization of microstructure in polyamide 6 prepared by polymerization of ϵ‐caprolactam in a corotating twin‐screw extruder. Results obtained by FTIR, WAXD, DSC, and DMTA are discussed in terms of the molecular mass of the polymer, the thermal history of the material, and the influence of residual monomer. © 1994 John Wiley & Sons, Inc.
A study of the degradation of polyethylene by high‐temperature dynamic light‐scattering
Authors: Wu Chi 
Published: April 2003

AbstractAfter passing throught an extuder, a small amount of degradation normally occurs in the high molecular weight tial of a broadly distrubuted polymer sample. This small amount of degradation counld dramatically affect the polymer viscoelastic properties. It is difficult to detect this type of degradion by using convetional analytical methods, such as hightemperature size exculsion chr omatography. An investisgation of this thype of degradation in a broadly distributed polyethylene sample was accomplished by using high‐temperature dynamic light‐scattering (HTDLS). We have shown that the measured line‐width (or the tsranslatinal diffusion coefficient) distrubuiton in the HTDLS is proportional to Mα with α = 3. 580 ± 0.005 so that the HTDLS is a very sensitive techique for detecting a very small amount of degradation im the high molecular weight tail. Another advantage of using the HTDLS is that the study does not intoduce further stress or perturbation into the sample. In study, we also investigated the thermal degradation of the polyelthylene sample in trichlorobenzene at high temperatures. We found that the polyethylene sample after the extrusion undergoes a thermal degradation more easily. © 1994 John Wiley & Sons, Inc.
Effect of different cross‐linking systems on properties of highly saturated nitrile rubber compounds
Authors: Hernández L. González , González J. L. De Benito , Rueda L. Ibarra , Díaz A. Rodríguez 
Published: April 2003

AbstractThe peroxide curing of highly saturated nitrile rubber was analyzed. Reactions such as chain scission occurred that account for the drop in physical properties. The results are compared with an alternative cross‐linking that is currently being assessed. With a new curing agent the chain‐scission reaction was not present and the properties of the compounds were improved. Finally, an estimation of the free volume of the materials tested was attempted by using the WLF equation. © 1994 John Wiley & Sons, Inc.
Synthesis of graft poly(ester ether) by ring‐opening copolymerization of epoxy‐terminated poly(ethylene glycol) with lactones
Authors: Ikeda Isao , Horie Naofumi , Suzuki Kimihiro 
Published: April 2003

AbstractThe copolymerization of epoxy‐terminated poly(ethylene glycol methyl ether) (CH3PEG–epoxide) with lactones such as ϵ‐caprolactone (CL) was carried out to prepare the PEG graft poly(ester ether). The methanol‐insoluble part of the reaction product was considered to be the graft copolymer. The graft copolymer was prepared using potassium tert‐butoxide or sodium methoxide as a catalyst. The apparent number‐average molecular weight (M̄n) of the graft copolymers increased with an increase in CL concentration and a decrease in the dielectric constant of the solvents. ß‐Propiolactone (PL) and δ‐valerolactone (VL) were also copolymerized with CH3PEG–epoxide as well as was CL. The apparent composition of the graft copolymers (lactone units/CH3PEG) was greater than the feed ratio of the two monomers in all cases. On the other hand, the composition of copolymers prepared with the copolymerization of low molecular weight epoxides such as phenyl glycidyl ether with VL was almost consistent with the feed ratio of the two monomers. © 1994 John Wiley & Sons, Inc.
Room‐temperature kinetics of castor‐oil‐based polyurethane/poly(2‐hydroxyethyl methacrylate) interpenetrating polymer networks
Authors: Suthar Bhikhu , Jadav Kanak , Dave Mayank 
Published: April 2003

AbstractThe kinetics aspects of the formation of castor‐oil‐based polyurethane/poly(2‐hydroxyethyl methacrylate) interpenetrating polymer networks (IPNs) were studied. The effect of parameters such as the polyurethane content, the activator, and acrylic cross‐linker on the kinetics of formation of IPN networks was examined at room temperature. The formation of the individual networks, polyurethane, poly(2‐hydroxethyl methacrylate), and their IPNs, was studied by measuring the decrease of absorbance of characteristic absorption peak of each system using IR spectroscopy. © 1994 John Wiley & Sons, Inc.
Preparation and application of low‐molecular‐weight poly(vinyl chloride). V. Preparation and characteristics of blended poly(vinyl chloride) by two‐step suspension polymerization
Authors: Yamamoto Kikuo , Maehara Takashi , Mitani Katsuo , Mizutani Yukio 
Published: April 2003

AbstractPoly(vinyl chloride) (PVC) with relatively broader molecular weight distribution (BMD‐PVC) was prepared by two‐step suspension polymerization: (1) preparation of poly(vinyl chloride) with relatively higher molecular weight (HMW‐PVC) and (2) successive preparation of poly(vinyl chloride) with relatively lower molecular weight (LMW‐PVC) in the presence of the resultant HMW‐PVC and 2‐mercaptoethanol as a chain transfer agent. Some properties of BMD‐PVC were investigated: fusion time, melt viscosity, discoloration time, tensile strength at yield, tensile modulus in tension, and elongation at break. © 1994 John Wiley & Sons, Inc.
Morphological implications of phase transitions in polymer solutions: Study of polyacrylonitrile‐based solutions
Authors: Akki Rashi , Desai P. , Abhiraman A. S. 
Published: April 2003

AbstractSolution‐based processing of infusible polymers usually involves large quantities of undesirable solvents and transport‐limited morphological evolution that is often difficult to control. The present study constitutes a rational exploration of the phase transitions in polymer solutions to form the basis for new processes that would diminish the abovementioned problems and also identify appropriate mechanisms for controlled generation of useful morphologies. The fundamental concepts in this regard are exemplified through solutions of acrylonitrile‐based homopolymer and copolymers, with important inferences drawn regarding their potential implications for the formation of fibers, films, and membranes. Thermodynamic and kinetic manipulation of transitions such as liquid–liquid phase separation and crystallization is shown to be effective in controlled generation of morphologies ranging from microporous to dense. © 1994 John Wiley & Sons, Inc.
Surface properties for poly(perfluoroalkylethyl methacrylate)/poly(n‐alkyl methacrylate)s mixtures
Authors: Park In Jun , Lee Soo‐Bok , Choi Chang Kyun 
Published: April 2003

AbstractA poly(perfluoroalkylethyl methacrylate) and a series of poly(n‐alkyl methacrylate)s such as poly(methyl methacrylate), poly(ethyl methacrylate), and poly(n‐butyl methacrylate) were prepared and used to investigate the surface properties of polymer mixtures containing a fluorinated homopolymer and a nonfluorinated homopolymer and the effect of the side‐chain length of poly(n‐alkyl methacrylate) on the surface free energy for the polymer mixtures. Contact angles were measured for the surfaces of polymer mixtures by varying the concentration of poly(perfluoroalkylethyl methacrylate). From the contact angle data, it can be inferred that most of the poly(perfluoroalkylethyl methacrylate) added to poly(n‐alkyl methacrylate)s is located in the outermost layer of polymer‐mixture surface. Surface free energies for the outermost surfaces of polymer mixtures were calculated from the contact angle data using Owen and Wendt's equation. The decrease in the surface free energy for the polymer mixture with the poly(perfluoroalkylethyl methacrylate) addition is more pronounced as the side‐chain length of poly(n‐alkyl methacrylate) decreases. Due to the steric effect of the side chain of poly(n‐alkyl methacrylate), the arrangement of the perfluoroalkylethyl group of poly(perfluoroalkylethyl methacrylate) to the air side is considerably hindered. The ESCA analysis of atomic compositions of the surface for the polymer mixture verified that poly(perfluoroalkylethyl methacrylate) is preferentially arranged and concentrates at the polymer mixture–air interface. The results of functional group compositions obtained by ESCA showed that the functional group composition of CF3 for the outermost layer has a more important effect on the surface free energy than that of CF2 and confirmed the hindrance of the arrangement of perfluoroalkylethyl group to the air side by the side chain of poly(n‐alkyl methacrylate). © 1994 John Wiley & Sons, Inc.
The permanence of UV absorbers in a rubber‐modified acrylic film by UV/visible spectrophotometry
Authors: Bonekamp J. E. , Maecker N. L. 
Published: April 2003

AbstractA new analysis technique for UV/visible spectrophotometry is described. This technique is used to accurately determine the retention of several UV absorbers (UVAs) in a rubbermodified acrylic film during xenon arc accelerated weathering. The effects of reflectance, light scattering, and matrix absorbance are deconvoluted from the total apparent absorbance, resulting in an absorbance spectrum due to the UVA alone. All of the UVAs studied exhibit significant losses upon xenon arc exposure, which has important implications for the longterm durability of polymers that utilize these stabilizers. © 1994 John Wiley & Sons, Inc.
Permanence of polymer stabilizers in hostile environments
Authors: Bell B. , Beyer D. E. , Maecker N. L. , Papenfus R. R. , Priddy D. B. 
Published: April 2003

AbstractAdditives are commonly formulated into polymers to stabilize them against thermo‐oxidative and photo‐oxidative degradation. However, the additives themselves undergo degradation in the polymers, especially when the polymers are placed in hostile environments. This study focuses on the degradation of additives in chemical and photo‐oxidizing environments; i.e., spas and xenon arc, respectively. HPLC‐UV/vis, FT‐IR, and GC‐MS techniques were utilized to follow the degradation chemistry of the additives. The chemistry was determined for additive degradation by spa chemicals, but the degradation chemistry of benzotriazoles remains elusive due to the insolubility of the resinous degradation products. © 1994 John Wiley & Sons, Inc.
Polylactide. III. Fiber preparation by spinning in precipitant vapor
Authors: Horáček I. , Kalíšek V. 
Published: April 2003

AbstractThe mechanical properties and morphologies of poly(L‐lactide) (PLLA) fibers, prepared by spinning in different vapor precipitants and hot drawing afterward, were studied in relation to fiber in vitro degradability. Petrolether, methanol, and ethanol were employed as precipitants. PLLA was used as‐polymerized, i.e., with 10% of residual L‐lactide. The tensile strength, structure, and degradability of obtained fibers were mainly governed by the nonsolvent concentration in the vapor phase. Using methanol as the precipitant for the fiber preparation, total tensile strength loss was achieved during 12 wk of in vitro degradation. © 1994 John Wiley & Sons, Inc.
Aqueous dispersion of polyurethanes containing ionic and nonionic hydrophilic segments
Authors: Kim Byung Kyu , Lee Young Min 
Published: April 2003

AbstractAqueous polyurethane (PU) dispersions were prepared from isophorone diisocyanate (IPDI), polytetramethylene glycol (PTMG), polypropylene glycol (PPG), polyethylene glycol (PEG), and dimethylol propionic acid (DMPA) as anionic center. The effects of the PEG/PTAd mixing ratio, type of polyether polyols, and hard segment content on the state of dispersion, surface, dynamic, and tensile properties of emulsion‐cast film were determined. With more incorporation of nonionic hydrophilic PEG, particle size of the emulsion and tensile strength of the emulsion‐cast film decreased, while the emulsion viscosity and elongation at break increased. Among ether type polyols, PTMG‐based PU generally showed superior mechanical properties. With increasing hard segment content, particle size, storage modulus (E′), and tensile strength increased. At the lowest hard segment content (36 wt %) tested in this experiment, soft segments crystallized and water swell decreased. © 1994 John Wiley & Sons, Inc.
Ion beam irradiation effect on gas permeation properties of polyimide films
Authors: Xu X. L. , Dolveck J. Y. , Boiteux G. , Escoubes M. , Monchanin M. , Dupin J. P. , Davenas J. 
Published: April 2003

AbstractThis study deals with the ion beam irradiation effect on gas permeation properties of polyimide films. 2 MeV α, 500 keV, and 170 keV N+ ions were used for modifying the membranes. It was found that there are two different effects according to the implantation dose. In the case of small‐dose irradiation, ion implantation causes a raise of permeability both for CH4 and H2. When the implantation dose reaches a more important level, the implanted membranes have at the same time high permselectivity for H2/CH4 and high permeability for H2. The relationships between the permeation properties and microstructure of the films are also discussed. © 1995 John Wiley & Sons, Inc.
Cross‐linked coatings by co‐reaction of isocyanate–methoxymethyl melamine systems
Authors: Ntsihlele E. S. , Pizzi A. 
Published: April 2003

AbstractTwo‐components methoxymethyl melamine/isocyanate and three‐components methoxymethyl melamine/isocyanate/polyol coating systems were studied. Methoxymethyl melamine was shown to react with isocyanate groups through the carbocation formed by splitting within the methoxymethyl group. In three‐components systems, methoxymethyl melamine/polyol and methoxymethyl melamine/isocyanate rections appear to occur, but not isocyanate/polyol reactions. This was ascribed to the release from the methoxymethyl melamine/polyol reaction of methanol which reacts more rapidly than the polyol with the isocyanate group. A blocked isocyanate was then used whereby the methoxymethyl melamine reacts at an earlier stage and urethane formation is delayed. Introducing the blocked isocyanate, however, required significant increase in cure temperature for the isocyanate/polyol reaction, narrowing the cure temperature window of the system. © 1995 John Wiley & Sons, Inc.
The effect of crystallization conditions on the properties of polyoxymethylene
Authors: Plummer C. J. G. , Menu P. , Cudré‐Mauroux N. , Kausch H.‐H. 
Published: April 2003

AbstractMeasurements using compact tension specimens machined from compression and injectionmolded plaques of polyoxymethylene show a systematic decrease in the plane‐strain critical stress intensity KIC for crack initiation with crystallization temperature and with molecular weight, but little change in the yield stress in plane strain compression tests. The variation in KIC with crystallization temperature has been accounted for in terms of the effective entanglement density in the damage zone ahead of the crack tip. The entanglement density is argued to decrease with increasing temperature owing to partial disentanglement of the polymer chains during lamellar folding. © 1995 John Wiley & Sons, Inc.
Strategies for supercritical CO2 fractionation of polydimethylsiloxane
Authors: Zhao X. , Watkins R. , Barton S. W. 
Published: April 2003

AbstractThe fractionation of polydimethylsiloxane (PDMS) using supercritical CO2 was studied to determine the parameters of pressure and temperature required to separate specific molecular weights. On a laboratory scale, we show that this fractionation method can quickly provide gram quantities of the polymer with a polydispersity of around 1.2 for molecular weights in excess of 200 kg/mol. This technique has obvious applications in the preparation of PDMS for surface‐related uses. © 1995 John Wiley & Sons, Inc.
Effect of silica filler on dynamic mechanical properties of lonic elastomer based on carboxylated nitrile rubber
Authors: Mandal U. K. , Tripathy D. K. , De S. K. 
Published: April 2003

AbstractVariation of dynamic mechanical propeties like storage modulus (E′) and loss tangent (tan δ) with temperature show the presence of two transitions in the carboxylated nitrile rubber (XNBR) molded in the presence of zinc oxide (ZnO). The low‐temperature transition is due to the glass–rubber transition (Tg) of XNBR, and the high‐temperature transition is due to formation of ionic clusters. Incorporation of reinforcing silica filler makes the high temperature transition more prominent and high filler loading casues a shift of the transition temperature to the higer side. It is believed that the rubber–filler interaction in the cluster region causes striking changes in the variation of E′ and tan δ with a double‐strain amplitude (DSA). © 1995 John Wiley & Sons, Inc.
Characterization of microstructure and fracture behavior of polypropylene/elastomer blends containing small crystal in elastomeric phase
Authors: Nomura Takao , Nishio Takeyoshi , Iwanami Kunio , Yokomizo Katsuyuki , Kitano Kissho , Toki Shigeyuki 
Published: April 2003

AbstractFracture behavior of polypropylene (PP)/ethylene–propylene–rubber (EPR) blends containing small crystal in elastomeric phase was investigated. Various ethylene‐α‐olefin co‐polymers (ECP) were used as crystal components and put into the elastomer phase of the blends. The crystallite size was controlled by changing the composition of the ECP. From thermal analysis and electron microscopic analysis, it was found that the ECP having a smaller crystal had better affinity to EPR and thus the crystal was finely dispersed in the elastomeric phase. The ECP with large crystallite size had poorer affinity to EPR and tended to segregate in the elastomeric phase. Scratch resistance and tensile elongation of blends were measured and it was found that the small crystal drastically improved the above properties while the large crystal deteriorated them. The dispersed small crystal was thought to act as a crosslinking point in the elastomeric phase. The reinforcement of the elastomeric phase by such quasi‐crosslinking structure was the possible reason for the improvement of the mechanical properties of the blends. © 1995 John Wiley & Sons, Inc.
Deformation and fracture of urethane–methacrylate resins
Authors: Elleithy R. H. , Hiltner A. , Baer E. , Fraser I. M. , Orton M. L. 
Published: April 2003

AbstractThe tensile properties of three urethane–methacrylate resins that varied in the soft segment content of the urethane were characterized. The strain birefringence at a circular hole was observed during loading–unloading cycles to progressivley higher displacements. The shear strain distribution at the hole was calculated from the isochromatic fringe contours and compared with results from linear elastic analysis. When the onset of nonlinearity, and the subsequent appearance of residual strain at the root of the hole, were correlated with features of the macroscopic stress‐displacement curves, three regions of prefracture deformation were defined. A region of linear elastic behavior was observed at the lowest strains. The maximum shear strain at the linear limit was the same in all the resins, and appeared to correlate with the yield condition at the hole. When the shear strain at the hole exceeded about 2.8%, the fringe patterns started to deviate from the elastic prediction. However, strain was fully recoverable in this region as indicated by the absence of residual birefringence at the hole after unloading. This region of nonlinear, recoverable deformation extended to progressively higher strains as the amount of urethane soft segment increased. This feature was attributed to the network structure of the urethane–methacrylate resins. A region characterized by nonrecoverable deformation at the hole followed at higher strains; the urethane soft segment content had a major effect on the amount of permanent deformation sustained before fracture. The fracture surfaces exhibited features typical of brittle fracture without crazing. © 1995 John Wiley & Sons, Inc.
Preparation of amphiphilic membranes using photosensitive polymers and their applications on the enzyme electrode
Authors: Liu Jui‐Hsiang , Chung Yi‐Chang , Lin Ming‐Ter 
Published: April 2003

AbstractTo decrease the mass transfer resistance of oxygen permeation and to improve the response of the enzyme electrode, a series of hydrophilic–hydrophobic polyvinylcinnamate (PVCin) membranes were developed. The PVCins were synthesized from polyvinyl alcohol using various amounts of cinnamoyl chlorides in the presence of alkali. The amphiphilic membranes were prepared by using photosensitive PVCin and/or sensitizers that were used instead of the traditional Teflon–hydrophilic two‐layer membranes. The properties of photocrosslinking, water and oxygen permeability of the amphiphilic membranes, the calibration curves, and the characteristics of the enzyme electrode prepared by the amphiphilic membranes were investigated. © 1995 John Wiley & Sons, Inc.
Study of radical copolymerization of tetrafluoroethylene with ethylene in bulk
Authors: Kostov G. K. , Nikolov Al. T. 
Published: April 2003

AbstractRadical copolymerization of tetrafluorethylene (TFE) with ethylene (E) by azo‐bis‐iso‐butyronitrile in the temperature interval 333–363 K, monomer pressure from 3.0 to 7.0 MPa at TFE/E molar ratio from 77/23 to 23/77 in bulk was carried out. The effect of reaction conditions on the yield, molecular weight, and polymer composition of copolymer synthesized was studied. White powdery alternating copolymers were obtained at TFE content in the monomer mixture from 65 to 85 mol %. Copolymerization rate R was described by the equation R = kM[ln] [Σ M]1.3 which was related to the heterophase character of the reaction. The reactivity ratio of TFE and E (0.067 ± 0.12 and 0.52 ± 0.18, respectively) and apparent activation energy Ea = 135 kJ/mol were found. The TFE and E block formation probabilities were calculated and compared with IR spectroscopy data. Melting point, entropy, and enthalpy of fusion of the entirely alternating copolymers were determined. Some of the basic properties of the alternating copolymers obtained were also studied. © 1995 John Wiley & Sons, Inc.
Electrical conduction in cellophane and polypyrrole composites and its use as an electrode in rechargeable batteries
Authors: Bhat N. V. , Yasmin S. 
Published: April 2003

AbstractElectrical properties of cellophane and polypyrrole [cello + PPy] composite films were investigated by the two‐probe method. The electrical conduction of composite films was studied as a function of voltage, temperature, and percentage content of PPy in the composite films. An attempt was made to use the [cello + PPy] composite films as electrodes in rechargeable batteries. © 1995 John Wiley & Sons, Inc.