bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas transport in polymer membrane at temperatures above and below glass transition point
Authors: Kumazawa H. , Wang J.‐S. , Naito K. , Messaoudi B. , Sada E. 
Published: April 2003

AbstractThe processes of gas sorption and permeation in a polymer membrane at temperatures above and below the glass‐transition point were examined using poly‐4‐methylpentene‐1 (glass‐transition temperature reported to be 40°C) as a membrane material. The permeabilities to O2 and N2 were independent of applied gas pressure at every temperature; the mean permeability coefficient to CO2 increased with increasing gas pressure. The logarithm of the mean permeability coefficient to CO2 increased linearly with gas pressure due to the plasticization effect induced by sorbed CO2. From the sorption isotherms for CO2 at 20 and 30°C it was judged that the glass transition was brought about by sorbed CO2 at temperatures below the glass‐transition point of the pure polymer. © 1994 John Wiley & Sons, Inc.
A study of reverse osmosis separation and permeation rate for sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide) membranes in different cationic forms
Authors: Chowdhury Geeta , Matsuura T. , Sourirajan S. 
Published: April 2003

AbstractThin film composite membranes were prepared by coating a thin layer of sulfonated poly(1,4‐dimethyl‐2,6‐phenylene oxide) polymer on the surface of a polysulfone ultrafiltration membrane. The membrane performance was studied when the sulfonate was either in the hydrogen form or loaded fully with an alkali metal cation. It was found that the permeation rate was greater than the pure water permeation rate, when the sulfonate was in the hydrogen form and the feed solution contained an alkali metal chloride solute. The permeation rate increased with an increase in the ionic radius of the alkali metal cation. With respect to membranes in which the sulfonate was loaded with an alkali metal cation, the pure water permeation rate was found to increase with a decrease in the ionic radius of the alkali metal cation. The permeation rate was the same as the pure water permeation rate when the membranes of the latter form were tested for reverse osmosis of aqueous solutions involving either sodium chloride or an organic solute. © 1994 John Wiley & Sons, Inc.
Ultraviolet radiation‐induced graft copolymerization of 2‐hydroxyethyl methacrylate onto polypropylene
Authors: Shukla S. R. , Athalye A. R. 
Published: April 2003

AbstractPolypropylene staple fibers were grafted with 2‐hydroxyethyl methacrylate (HEMA) using ultraviolet radiation in the presence of three different photoinitiators, uranyl nitrate (UN), ceric ammonium nitrate (CAN), and benzoin ethyl ether (BEE), separately. The parameters of grafting were optimized for obtaining maximum graft add‐on. BEE appeared to be a better photoinitiator than the other two, giving maximum possible graft add‐on. CAN, as a chemical initiator, did not show significant improvement in grafting. The moisture regain of the grafted polypropylene increased in proportion with the graft add‐on. Dyeing with reactive dye could give only light color to the grafted fiber. Possible explanations have been given. © 1994 John Wiley & Sons, Inc.
Comparison of hydrodynamic and rheological properties of dilute solutions of a styrene‐hydrogenated butadiene copolymer in aliphatic solvents by light scattering and viscometric techniques
Authors: Bezot P. , Hesse–Bezot C. , Elmakoudi B. , Constants B. , Faure D. , Hoornaert P. 
Published: April 2003

AbstractDilute solution of a styrene‐hydrogenated butadiene copolymer, a viscosity index improver, were studied by static and dynamic light‐scattering techniques. In n‐hexane (a model solvent for paraffinic oils) and a mineral base oil, aggregation is observed below 30°C. In cyclohexane (a model solvent for napthenic oils) only isolated polymers are present in the whole temperature range.Kinematic viscometric measurements from 20 to 60°C in the mineral oil show a continuous increase of the intrinsic viscosity together with a decrease of kH, the Huggins coefficient, from 2.5 to 0.5. At shear rates between 5000 and 40000s−1, a large shear thinning is observed at room temperature for the polymer in the mineral base oil. This effect progressively disappears as the temperature increases and the suspension becomes Newtonian near 100°C. All results can be interpreted in terms of micelle formation. © 1994 John Wiley & Sons, Inc.
Calcium alginate gel fibers: Influence of alginate source and gel structure on fiber strength
Authors: Moe Størker , Skjåk‐Bræk Gudmund , Smidsrød Olav , Ichijo Hisao 
Published: April 2003

AbstractThe low‐deformation extension modulus was measured for Ca–alginate gel fibers prepared from alginates of different compositions and molecular weights. The modulus showed an increase with increasing molecular weight for alginates of the same composition and sequence parameters. Fibers prepared with an inhomogeneous polymer concentration profile showed higher moduli than did fibers with a homogeneous polymer concentration profile. The higher modulus observed for fiber prepared from an alginate with low Ca2+ affinity is tentatively explained as resulting from a higher degree of polymer chain alignment. © 1994 John Wiley & Sons, Inc.
Composites of anionic (co)polyamides (nylon 6/nylon 12) with short glass E‐fibers. Preparation and properties
Authors: Arvanitoyannis I. , Psomiadou E. 
Published: April 2003

AbstractThe recent high demand of thermoplastic composites has induced an extensive experimentation and utilization of polyamides as thermoplastic sheet composites. The hand layup technique was used for the preparation of the glass fiber polyamide composites studied here. The percentage crystallinity of the composites was determined with a variety of techniques such as differential thermal analysis (DTA), wide‐angle X‐ray diffraction (WAXD) patterns, and density measurements. Glass transitions (Tg) and melting temperatures (Tm) were determined with DTA and dynamic mechanical thermal analyzer (DMTA) measurements. Finally, the mechanical properties (stress–strain curves and compression tests) were investigated and the results were correlated to the glass fiber content, and the percentage of the comonomer unit (caprolactam and laurolactam) in the polyamide composite. © 1994 John Wiley & Sons, Inc.
Characteristics of permeation and separation for propanol isomers through poly(vinyl alcohol) membranes containing cyclodextrin
Authors: Miyata Takashi , Iwamoto Tooru , Uragami Tadashi 
Published: April 2003

AbstractPoly(vinyl alcohol) membranes containing cyclodextrin (CD–PVA membrane) were prepared and characteristics of permeation and separation for propanol (PrOH) isomers through the CD–PVA membranes were investigated by pervaporation and evapomeation. Evapomeation was more effective for the separation of PrOH isomers through the CD–PVA membrane than was pervaporation. The CD–PVA membrane more preferentially permeated n‐PrOH than i‐PrOH from their mixtures. In particular, the mixture of 10 wt % n‐PrOH concentration was concentrated to about 45 wt % through the CD–PVA membrane. Both permeability and selectivity for n‐PrOH were improved with an increase of CD content in the membrane. The results were supported by the fact that the affinity of CD for n‐PrOH was stronger than that for i‐PrOH. The permeation mechanism of PrOH isomers through the CD–PVA membrane is discussed based on the solution–diffusion theory. © 1994 John Wiley & Sons, Inc.
The influence of processing terms of chitosan membranes made of differently deacetylated chitin on the crystalline structure of membranes
Authors: Urbanczyk G. W. , Lipp‐Symonowicz B. 
Published: April 2003

AbstractThe crystalline structure of chitosan membranes made of a high degree of (90%) and low degree of (60%) deacetylated chitin by various regeneration processes was studied. The results of X‐ray and IR spectroscopy investigations testify that the type of crystalline structre, the degree of crystallinity, and the average lateral crystallite size depend basically on the deacetylation degree of the chitin utilized in preparing the membranes. © 1994 John Wiley & Sons, Inc.
The ductile‐to‐quasi‐brittle transition of particulate‐filled thermoplastic polyester
Authors: Li J. X. , Silverstein M. , Hiltner A. , Baer E. 
Published: April 2003

AbstractThe effects of various filler characteristics on the ductility of filled amorphous copolyester, Kodar 6763, have been examined. The five fillers in the study included two calcium terephthalates with different particle‐size distributions and three calcium carbonates, also with different particle‐size distributions. One of the calcium carbonate fillers had received a surface treatment. The increase in Young's modulus with increasing filler content was the same for all fillers and was satisfactorily described by Kerner's equation. The only filler to affect the yield stress was the surface‐treated calcium carbonate; in this case, the decrease in yield stress was attributed to cracking and splitting of aggregated particles. A sharp drop in fracture strain was observed with increasing filler content. This ductile‐to‐quasi‐brittle transition occurred when the fracture mode changed from fracture during strain‐hardening of neck propagation to fracture during neck formation. The critical filler content of the ductile‐to‐quasi‐brittle transition varied from one filler to another. A simple model qualitatively described the decrease in critical filler content with increasing breadth of the particlesize distribution and, in particular, with increasing volume percent of large particle in the distribution. © 1994 John Wiley & Sons, Inc.
A simple dilatometer for thermoset cure shrinkage and thermal expansion measurements
Authors: Snow Arthur W. , Armistead J. Paul 
Published: April 2003

AbstractA simple capillary and bulb mercury dilatometer designed for specific volume measurements on thermoset resin systems during the curing reaction and as a function of temperature is described. The design, calibration, operation, data treatment, and error analysis are presented in detail, with data on the bisphenol A dicyanate resin system used as an example. Particular attention is directed at experimental difficulties such as monomer/prepolymer degassing, filling the dilatometer under vacuum, adhesive distortion of the curing resin on the dilatometer bulb, and the dilatometer bulb to capillary connection problem. © 1994 John Wiley & Sons, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
Interfacial synthesis and characterization of random and segmented block bisphenol A–tetrabromobisphenol A copolycarbonates
Authors: Marks M. J. 
Published: April 2003

AbstractThe chain sequence architecture of bisphenol A–tetrabromobisphenol A copolycarbonates depends on the process employed to prepare them. An interfacial process involving a single‐step phosgenation produces a segmented block copolymer, contrary to previous assumptions. An interfacial two‐step phosgenation process allows the preparation of random copolycarbonates. In each process the control of the pH of the acqueous phase of the two phase reaction mixture is required to achieve complete comonomer conversion to copolymer and to obtain the desired sequence architecture. The chain sequence architecture of these copolycarbonates can be estimated by examination of their Fourier transform infrared spectra. The relative bandwidth of the carbonate stretching band is roughly proportional to the copolycarbonate number average sequence length, allowing the facile distinction between block and random copolymers. The number average sequence lengths of these copolycarbonates were quantified by carbon‐13 NMR spectroscopy. These analyses showed that the one‐step phosgenation process yields segmented block copolycarbonates having number average sequence lengths from about 4 to 9, and the two‐step phosgenation process produces random copolycarbonates having sequence lengths from 1.6 to 2. The distribution of the aromatic carbon triads of these random copolymers shows them to have an alternate‐segmented block architecture, which is consistent with the synthesis conditions, rather than a statistically random distribution of comonomer segments. Dynamic mechanical analysis of two of these copolycarbonates shows a dependence of their low temperature secondary transitions on the copolymer sequence structure. A segmented block copolycarbonate, having a number average sequence length of about 4, displays two distinct peaks in its tan δ curve at temperatures corresponding to those transitions observed in the respective homopolymers. The tan δ curve of a random copolycarbonate shows a single low temperature secondary transition midway between those of the homopolymer. © 1994 John Wiley & Sons, Inc.
Synthesis, characterization, and coating applications of chlorinated hydroxyrubber
Authors: Thames Shelby F. , He Z. Alex 
Published: April 2003

AbstractChlorinated hydroxyrubber has been synthesized via the chlorination of hydroxylated liquid natural rubber. The formulation examples and coatings properties of two‐component chlorinated hydroxyrubber polyurethane coatings are described. © 1994 John Wiley & Sons, Inc.
Fracture toughness of adhesive joints. I. Relationship between strain energy release rates in three different fracture modes and adhesive strengths
Authors: Lim Won Woo , Hatano Yasunori , Mizumachi Hiroshi 
Published: April 2003

AbstractThe three strain energy release rates, GIC, GIIC, and GIIIC, of adhesive joints can be attributed to their ability to resist crack propagation of solids in the adhesive layer. The dependencies of GIC, GIIC, and GIIIC on crack lengths for various adhesive joints were determined using the double‐cantilever beam specimen by a compliance method. The two types of adhesive strengths, i.e., adhesive tensile strength and adhesive shear strength, corresponding to GIC and GIIC, respectively, were carried out at room temperature and 65% RH with a crosshead speed of 10 mm/min. The GIC, GIIC, and GIIIC were dependent upon crack length and had constant values irrespective of geometric parameters of the specimen over the crack length of five times adherend thickness, 0.65 (= crack length over half a length of span) and eight times adherend thickness, respectively. In the region of the crack length, we determined the following increasing order of fracture toughness: GIC < GIIIC < GIIC. A positive correlation was found between adhesive tensile strength and GIC. A significant relation between adhesive shear strength and GIIC was not found in this work. Further studies are needed to clarify the relation between adhesive shear strength and GIIC with general adhesives. © 1994 John Wiley & Sons, Inc.
Polymer blend: A novel method for the preparation of a natural rubber–carboxylated nitrile rubber blend
Authors: Naskar Nityananda , Biswas Tapasi , Basu Dipak Kr. 
Published: April 2003

AbstractBis(diisopropyl)thiophosphoryl disfulfide (DIPDIS) can be successfully used to form a blend comprising polar carboxylated nitrile rubber (XNBR) and nonpolar NR through a chemical link between the two. It is revealed from the study that the physical properties of the vulcanizates obtained from the NR‐XNBR blend could be significantly improved by the judicious selection of the NR:XNBR ratio. These properties can further be improved by two‐stage vulcanization as described in the procedure. The SEM study reveals that it is possible to form a coherent blend of NR and XNBR in the presence of DIPDIS. © 1994 John Wiley & Sons, Inc.
Oxidative damage and recovery of silicone rubber surfaces. I. X‐ray photoelectron spectroscopic study
Authors: Tóth András , Bertóti Imre , Blazsó Marianne , Bánhegyi György , Bognar Alajos , Szaplonczay Pál 
Published: April 2003

AbstractThe oxidative degradation of silicone rubber surfaces in air plasmas obtained by RF or corona discharges and the subsequent recovery process were studied by X‐ray photoelectron spectroscopy (XPS or ESCA). Using relatively short treatment times (5 min), the surface oxygen content was found to increase and that of carbon to decrease. Within 1 day some recovery toward the original composition was observed, but it was far from being complete. Angle‐dependent measurements have shown an almost total recovery in the topmost layer. The degree of surface degradation of a solvent‐extracted sample was much higher while its recovery was much smaller than the corresponding features of the nonextracted sample. According to GC and GC–MS analyses the extract contained a mixture of cyclic, and, in a minor quantity, linear dimethylsiloxane oligomers. Based on the above results the following steps were proposed for the oxidative damage and the subsequent recovery processes on silicone rubber surfaces: first the majority of surface methyl groups is removed and an oxidized layer containing Si atoms bound to 3 or 4 oxygens appears. The surface is later covered by a very thin (2–3 nm thick) “silicone oil” layer due to migration of low‐molecular‐weight components from the bulk. This diffusion‐controlled migration step plays a more important role in the recovery process than the eventual reorientation of the newly formed polar groups from the surface toward the bulk. The proposed model is discussed in the light of published data. © 1994 John Wiley & Sons, Inc.
Morphological studies of bisphenol series thermotropic liquid crystalline wholly aromatic copolyesters
Authors: Zhao Zhouming , Wu Xuqin , Lin Yongwei , McLean John 
Published: April 2003

AbstractA family of aromatic thermotropic liquid crystal (TLC) copolyesters are prepared based on terephthalic acid (TPA), isophthalic acid (IPA), p‐hydroxybenzoic acid (HBA), and a family of bisphenols. The morphological behaviors of the copolyesters are studied by using polarized optical microscopy, small‐angle light scattering (SALS), and depolarized light intensity (DLI) analysis. The copolyester melts exhibit nematic mesophase textures within wide temperature ranges without showing transitions to isotropic phases. The textures under different temperatures and deformation conditions are investigated. Scattering patterns of the mesophases change greatly during shear deformation and relaxation. The early formation of the mesophases is a one‐dimension heterogeneous nucleation based on isothermal condition. © 1994 John Wiley & Sons, Inc.
Surface modification of UHMWPE fibers
Authors: Silverstein M. S. , Breuer O. , Dodiuk H. 
Published: April 2003

AbstractUltrahigh molecular weight polyethylene (UHMWPE) fibers have a high specific strength, high specific modulus, and outstanding toughness, but their poor adhesive properties has limited their use for composite material applications. In this research, the effects of chemical etching on the surface chemistry and topography have been explored using chromic acid, potassium permanganate, and hydrogen peroxide etching. The smooth surface observed on the as‐received fiber was rich in ether and/or hydroxyl oxygen. This smooth surface resulted from the presence of an outer layer, a weak boundary layer, that was removed by all the etchants. A fibrillar structural hierarchy was revealed beneath this outer layer and the fiber was relatively unchanged by further etching. Chromic acid, the strongest etchant studied, produced a rough and oxidized UHMWPE surface with both ether and carbonyl oxygen. The combination of outer layer removal, roughness, and changes in oxygen bonding helps explain the improved adhesion on chromic acid etching in spite of the reduction in surface oxygen. Neither hydrogen peroxide nor potassium permanganate etching roughened or oxidized the surface to a great extent and neither yielded improved adhesion. © 1994 John Wiley & Sons, Inc.
Ductile tearing instability in phenolphthalein poly(ether ketone)
Authors: Han Yanchun , Yang Yuming , Li Binyao , Feng Zhiliu 
Published: April 2003

AbstractPhenolphthalein poly(ether ketone) (PEK‐C)can fail by tearing instability when the elastic contraction is greater than the plastic extension due to crack growth. Tearing instability (TIS) theory developed by Paris and coworkers describes the effect of specimen geometry on the ductile fracture properties of polymers. The stability of crack growth in three‐point bend specimens depends on the specimen's dimensions. In this article, tearing instability theory is applied to describe the ductile tearing instability of PEK‐C at different temperatures. The temperature dependence of tearing modulusTm,dJ/dδa, and the relationship betweendJ/dδaand yield stress are discussed. © 1994 John Wiley & Sons, Inc.
Electrostriction of highly swollen polymer gel: Possible application for gel actuator
Authors: Hirai Toshihiro , Nemoto Hiroshi , Hirai Mitsuhiro , Hayashi Sadao 
Published: April 2003

AbstractA gel of poly(vinyl alcohol) highly swollen with dimethyl sulfoxide was demonstrated to actuate at a much faster rate (more than 1000 times) than those reported on conventional gel actuators in air and to flap a wing of 12.5 cm at a rate of 2 Hz with a span of 10 cm by periodically applying electric field. The action (8% in length) induced by the electric field reached several hundreds times larger than those reported on the conventional ferroelectric solid materials. The electrostrictive gel was, thus, found to be a promising candidate material as a novel type of actuator or artificial muscle by having overcome some difficulties in responding time, electrochemical reactions on the electrodes, and magnitude of action in conventional methods or materials. © 1994 John Wiley & Sons, Inc.
Transient shear response of liquid crystal‐forming hydroxypropyl cellulose solution in dimethylacetamide. II. Correlation between band formation and stress relaxation
Authors: Suto Shinichi , Kohmoto Kenichi , Abe Atsushi 
Published: April 2003

AbstractThe simultaneous determination of band formation and stress relaxation behavior was carried out using a parallel glass plates apparatus for the liquid crystalline hydroxypropyl cellulose solutions. The effects of shear rate and concentration on both behavior were mainly determined. The dependence of band formation on shear rate was the same as that reported in the literature: the higher shear rate is, the more rapidly the band forms. The band formation depended on the concentration. The effect of concentration appeared to depend on the solution phase (biphase or fully liquid crystalline phase); for the biphasic solutions, the band formed rapidly with increasing concentration, whereas for the fully liquid crystalline solutions, the band formed rapidly with decreasing concentration. Qualitatively, the stress relaxation was divided into two regions; one was the first rapid relaxation process, and another was the secondary slow relaxation one. It was speculated that the band does not form in the first process, but begins to form around the beginning of the secondary process. © 1994 John Wiley & Sons, Inc.
Grafting of maleic anhydride onto polypropylene: Synthesis and characterization
Authors: Sathe Sachin N. , Rao G. S. Srinivasa , Devi Surekha 
Published: April 2003

AbstractIsotactic polypropylene was grafted with maleic anhydride using benzoyl peroxide as an initiator and toluene as a solvent. Effects of various parameters such as monomer and initiator concentration, reaction time, and reaction temperature on percentage grafting were studied. Effect of various solvents on extent of grafting was also studied. The maximum extent of grafting achieved was 5.3%. The graft copolymers were characterized by i.r., thermal, viscometric, and contact angle studies. Improved thermal stability and decreased intrinsic viscosity and critical surface tension were observed for graft copolymers. © 1994 John Wiley & Sons, Inc.