bluuebunny/crossref_metadata_2025 huggingface dataset:
Peroxide modification of a multicomponent polymer blend with potential applications in recycling
Authors: Vivier T. , Xanthos M.
Published: April 2003

A mixture of seven immiscible “virgin” plastics, namely low and high density polyethylene (LDPE and HDPE), polypropylene (PP), polyvinyl chloride (PVC), crystal and high impact polystyrene (PS and HIPS), and polyethylene terephthalate (PET), in proportions representative of those currently found in post‐consumer plastics containers, was compounded in a corotating twin‐screw extruder. The mechanical properties of the blend were improved through the addition of relatively high concentrations of a dialkyl peroxide which was also found to drastically affect the blend morphology. The results are interpreted in terms of improved dispersive mixing favored by the similarity in the rheological behavior of the modified blend components, improved physical properties of certain blend components upon peroxide modification, and, possibly, enhanced intefacial adhesion. © 1994 John Wiley & Sons, Inc.
β‐radiation effects on PVC materials: Methodology for studying chemical modifications
Authors: Yagoubi N. , Baillet A. , Legendre B. , Rabaron A. , Ferrier D.
Published: April 2003

The radiosterilization of plastic packaging theoretically induces two types of chemical modifications, namely reticulation and cleavage, that depend not only on the chemical structure of the polymer, but also on the kind and dose of radiation. This article proposes a methodology for studying plasticized polyvinylchloride (PVC) behavior submitted to β radiation. Analytical techniques such as thermogravimetric analysis (TGA) and size exclusion chromatography (SEC) coupled with a light scattering detector were used in this study. SEC has informed us directly on the modifications (reticulation, scission) that intervened after a radiotreatment; TGA allowed us to highlight polymer structural changes. In addition, FTIR was employed to demonstrate an intermolecular dehydrochlorination following the radiotreatment. The results of these investigations permitted us to demonstrate both a reticulation and a scission phenomena within the PVC polymer. © 1994 John Wiley & Sons, Inc.
Preparation and characterization of perlite‐filled high‐density polyethylenes. II. Thermal and flow properties
Authors: Akin‐öktem G. , Tinçer T.
Published: April 2003

Thermal and flow properties of perlite‐filled high‐density polyethylenes (HDPE), studied in the first part of the paper, are discussed. Maximum peak temperatures of endotherms (Tmp) and the corresponding relative peak heights were examined by differential scanning calorimetry (DSC). The data obtained from a Brabender torque rheometer were evaluated to find the melt viscosities at low share rate during preparation of perlite–HDPE composities. The filler concentration, type of HDPEs, and the use of γ‐APS are found to be effective and influential factors on the thermal and flow propertis of these composities. © 1994 John Wiley & Sons, Inc.
Characterization of plasma‐induced graft polymerization of 2‐hydroxyethyl methacrylate onto silicone rubber
Authors: Lee Shyh‐Dar , Hsiue Ging‐Ho , Wang Chee‐Chan
Published: April 2003

Graft copolymerization of 2‐hydroxyethyl methacrylate (HEMA) as attempted onto the surface of silicone rubber membrane, which was pretreated by Ar‐plasma, then exposed in oxygen to introduce a peroxide group. The effect of the amount of HEMA grafted on Arplasma‐treated and graft copolymerization was examined for various parameters of power, pressure, time, reaction time, and concentration of HEMA aqueous solution. The surfaces were characterized by ATR–FTIR, ESCA, contact angle, and SEM. PHEMA was indicated by ATR–FTIR and ESCA analysis to be present successfully onto the grafted surface of silicone rubber membrane. The stable wettability, as demonstrated once the PHEMA grafted films, indicated contact with a hydrated environment by the study of contact angle. © 1994 John Wiley & Sons, Inc.
Physical and mechanical properties of highly plasticized pectin/starch films
Authors: Coffin David R. , Fishman Marshall L.
Published: April 2003

Blends of citrus pectin and high amylose starch plasticized with glycerine were investigated to determine the effect of compositional variables on film properties. Several films with representative compositions were made from sugar beet and almond pectin, and tested for comparison. The films were cast from water onto glass plates, dried, and removed. Mechanical analysis was done using a Rheometrics RSA II solids analyzer. Increasing the glycerine concentration led to decreases in static modulus, dynamic modulus, and tensile strength, but to increases in elongation. Increasing levels of starch in the blend lowered the effect of glycerine on mechanical properties. Oxygen permeability of the films was extremely low. Sugar‐beet pectin and almond pectin gave films with mechanical properties comparable to those made with citrus pectin. © 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.
Interactions between heterogeneous surfaces of polymers and water
Authors: Murase H. , Nanishi K. , Kogure H. , Fujibayashi T. , Tamura K. , Haruta N.
Published: April 2003

Preliminary investigations for the interactions between surfaces of polymers and water were conducted by the measurements of contact (θ) and sliding‐angles (α) with water. Work of adhesion (W) and interaction energies were subsequently calculated by using the values of θ and α, respectively. For the evaluation of actual performances of polymeric materials, shear strength of ice adhesion and snow accretion were measured. Characteristics of homogeneous surfaces of polymers in the interaction with water were obtained. On the basis of these concepts, the materials with heterogeneous surfaces were synthesized. Results of surface characterizations in these polymers showed that the relationship between θ and α, and the other surface attributes are very different according to polymer systems. The surface controlled energetically and morphologically, and the superior hydrophobic property prevented the snow accretion, but not ice adhesion. On the other hand, the organopolysiloxane modified with lithium compound provided the lowest strength of ice adhesion, but a poor capability of snow repellency. In the structural and energetic viewpoints', interactions between heterogeneous surfaces and water (snow and ice) were discussed. For the theoretical prediction, the intermolecular energies between model polymers and water were calculated by using a molecular orbital SCF method. The order of interactions calculated were coincident with experimental values deduced from α, but not from θ. The advantage of heterogeneity of surface was supported by the theoretical understanding. © 1994 John Wiley & Sons, Inc.
Characterization and application of crosslinkers for polyurethane aqueous systems: Isopropylidene malonate‐blocked isocyanurate
Authors: Mirčeva A. , Žigon M. , Malavašič T.
Published: April 2003

An adduct of hexamethylene isocyanurate and isopropylidene malonate was prepared and tested as a crosslinker in a one‐pack water‐borne polyurethane system. It was characterized by FTIR, NMR, and SEC; the blocking and curing courses were followed by FTIR and DSC. The crosslinker was a mixture of various oligomers having mainly amide‐type linkages. The cure analysis showed that cleavage of the malonate ring started at around 110°C and was followed by the formation of ester‐type products. After 30 min of heating at 130°C the insoluble part of crosslinked polyurethane films exceeded 80%. © 1994 John Wiley & Sons, Inc.
Environmental stress cracking behavior of short‐chain branch polyethylenes in Igepal solution under a constant load
Authors: Yeh J. T. , Chen Jung‐Horng , Hong Huei‐Song
Published: April 2003

An investigation of the influence of branch length and crystallinity on environmental stress cracking properties of short‐chain branch polyethylenes (SBPEs) in Igepal solution is reported. The precise value of Igepal transition time (ITT) and difference between the failure process of SBPEs in air and in Igepal solution were determined by comparing their plots of notch opening displacements vs. time in air and in Igepal solution. Igepal transition time can only be found as the failure time (tfI) is greater than the critical time Igepal required to “accelerate” the fracture of SBPEs in Igepal solution. Prior to ITT, time dependence of notch opening displacements and fracture surfaces of samples in Igepal solution were similar to those in air. In contrast, obvious voids appeared in the base of craze and crazelike structures containing clear voids were found on the fracture remnants of samples with tfI longer than their ITTs. The value of ITT and tfI were found to increase significantly for samples associated with higher crystallinity. However, no significant difference in value of ITT was found for samples with the same crystallinity, tie‐molecule density, molecular weight, branch frequency, but different branch length. Finally, environmental stress cracking resistance (ESCR) and tfI of SBPEs in Igepal solution increased dramatically as the short‐chain branch length increased. This dramatic improvement in environmental stress cracking properties with short‐chain branch length is attributed to the increasing sliding resistance of the polymer chains through the crystal and through the entanglement in amorphous region at time before and after ITT. © 1994 John Wiley & Sons, Inc.
Electrorheological effect of liquid crystalline polymers
Authors: Inoue A. , Maniwa S.
Published: April 2003

Large increases in shear stress upon application of a 2.0 kV/mm electric field were observed in homogeneous fluids composed of polysiloxane‐based liquid crystalline polymers (LCPs) in dimethyl silicone at a shear rate of 200 s−1. The increase was largest (about 3,000 Pa at 50°C) with LCP consisting of a polysiloxane bearing mesogenic groups as side chains. With LCP having the mesogenic groups within the main chain, the maximum increase was about 1,300 Pa at 90°C. It was about 400 Pa at 30°C with LCP having the mesogenic groups at both ends only (biterminal), and several Pa at 30°C with LCP having the mesogenic group at one end only (monoterminal). The increases were smaller with mesogenic groups of lower positive dielectric anisotropy in the side chain LCP. The side chain, biterminal, and monoterminal LCPs exhibited Newtonian flow in the electric field and shear stress yield at low shear rates in its absence. The complex dynamic modulus and viscosity of the side chain LCP in the electric field showed no dependence on strain at deformation displacements approaching 5°, but in its absence were generally strain‐dependent, and suggest the strong electrorheological effect of these homogeneous LCP fluids is related to a flexible‐chain linkage between their crystalline domains. © 1995 John Wiley & Sons, Inc.
Physical properties of moldings from liquefied wood resins
Authors: Lin Lianzhen , Yoshioka Mariko , Yao Yaoguang , Shiraishi Nobuo
Published: April 2003

The liquefied wood resins obtained by liquefying wood in the presence of phenol using phosphoric acid as a catalyst were applied to prepare the moldings by using hexamine as a hardener. The effects of the molding conditions and the moldings' compositions on flexural properties and water‐sorption kinetics of the moldings were investigated. It was found that the liquefied wood resins had satisfactory and almost uniform curing reactivity, although they were composed of different kinds of wood components. The flexural properties of the liquefied wood moldings were enhanced with an increase in the amount of combined phenol within the liquefied wood and became comparable to those of the commercial novolak when the amounts of combined phenol were larger than 75%. Furthermore, it was also found that with an increase in the content of wood fillers the flexural properties of the liquefied wood moldings were enhanced more effectively than were the cases of the commercial novolak moldings, exhibiting that the liquefied wood resins could gain a greater reinforced effect from compounding with the wood fillers than did the commercial novolak resins, and the greater the amount of combined phenol, the higher the reinforcing performance of wood fillers. In addition, water‐sorption measurements and the SEM observations of the moldings indicated that the liquefied wood resins had much greater hydrophilicity than that of the novolak and revealed a greater compatibility with wood fillers. © 1995 John Wiley & Sons, Inc.
Effect of process conditions on birefringence development in injection‐molded parts. I. Numerical analysis
Authors: Chen Shia Chung , Chen Yung Cheng
Published: April 2003

Analysis of the injection‐molding process based on Leonov viscoelastic fluid model has been employed to study the effects of process conditions on the residual stress and birefringence development in injection‐molded parts during the entire molding process. An integrated formulation was derived and numerically implemented to solve the nonisothermal, compressible, and viscoelastic nature of polymer melt flow. Simulations under process conditions of different melt temperatures, mold temperatures, filling speeds, and packing pressures are performed to predict the birefringence variation in both gapwise and planar direction. It has been found that melt temperature and the associated frozen layer thickness are the dominant factors that determine the birefringence development within the molded part. For a higher mold temperature, melt temperature, and injection speed, the averaged birefringence along gapwise direction is lower. The birefringence also increases significantly with the increased packing pressure especially along gate area. The simulated results show good consistency with those measured experimentally. © 1995 John Wiley & Sons, Inc.
A study on the polymer layer‐forming phenomena in a rotating disk polycondensation reactor
Authors: Cheong Seong Ill , Choi Kyu Yong
Published: April 2003

An experimental study is reported on the measurement of polymer melt film thickness in a rotating disk polycondensation reactor. The layer thickness of molten poly(ethylene terephthalate) on a rotating disk was measured at 280°C using an electrical conductivity probe at different radial and angular positions. It was observed that the polymer film thickness was not uniform in both radial and angular positions, particularly for high molecular weight polymers. For the slowly rotating disk system employed in our experimental study, the disk rotational speed and gravity effects on the polymer‐layer formation were found to be quite significant. The experimental results were used to develop an empirical correlation for the calculation of polymer film thickness and polymer melt holdup on a rotating disk. © 1995 John Wiley & Sons, Inc.
Synthesis of difuran diesters from furfural, and their evaluation as plasticizers for polyvinyl chloride
Authors: Sanderson R. D. , Schneider D. F. , Schreuder I.
Published: April 2003

The compounds 1,1‐bis[5‐(2‐ethylhexyl, 2‐octyl, hexyl, and butyl)carboxylate‐2‐furyl)ethane, and 5,5′‐dihexylcarboxylate‐2,2′ bifuran were synthesized from furfural and characterized for their plasticizing abilities toward polyvinyl chloride (PVC) by dynamic mechanical thermal analyses (DMTA) with di‐(2‐ethylhexyl)phthalate (DOP)as the standard of reference. DMTA gave values for the depression of the glass‐transition temperature (Tg) per mass fraction of plasticizer, and it also yielded a set of parameters, relative to those of DOP, which describe the compatability of the furan diesters with PVC. These values are compared to those of DOP and furan diesters incorporating only one furan ring in the molecular structure, which have previously been tested by this method. The difuran plasticizers are less efficient in lowering Tg than the monofuran plasticizers or DOP, with 1,1‐bis[5‐(2‐octyl)carboxylate‐2‐furyl]ethane the least efficient and 1,1‐bis(5‐hexylcarboxylate‐2‐furyl)ethane the most efficient. On average the compatability toward PVC is better than that of DOP, and similar to that of analogous monofuran structures. © 1995 John Wiley & Sons, Inc.
Rheological behavior of blends of natural rubber and styrene–butadiene rubber latices
Authors: Varkey Jyothi T. , Thomas Sabu , Rao S. Someswara
Published: April 2003

The rheological behavior of blends of natural rubber (NR) and styrene–butadiene rubber (SBR) latices has been studied with reference to the effects of blend ratio, shear rate, surface‐active agents (casein and sodium carboxymethyl cellulose), and temperature. When the SBR content was less than 50%, the viscosities of the blends appeared to be a nonadditive function of the viscosities of the constituent homopolymers; i.e., a positive deviation was observed. This was due to the structural buildup of the SBR domains. The SBR domains underwent agglomeration and consequently so‐called microflocculation took place. The viscosities of all the blends were found to decrease with increase of temperature and shear rate. The increase in temperature and shear rate marginally weakened the structural buildup as evidenced by the lowering of viscosity. As the SBR content in the system increased, the pseudoplasticity of the blend increased. Even in the presence of surface‐active agents the blends showed composition‐dependent positive deviation. However, surface‐active agents marginally reduced the extent of structural buildup by reducing the microflocculation behavior of SBR domains. © 1995 John Wiley & Sons, Inc.
Synthesis of calcium carbonate–chitosan composites via biomimetic processing
Authors: Zhang Sukun , Gonsalves K. E.
Published: April 2003

The crystal growth of calcium carbonate on a chitosan substrate was achieved using a supersaturated calcium carbonate solution, at different concentrations of polyacrylic acid (PAA) as an additive. Several techniques have been employed to characterize the systems. The pH of the solution as the one of indices was used to monitor the crystallization. In the absence of polyacrylic acid, the pH of the solution changed from 6.00 to 8.50 during the crystallization; meanwhile, sporadic nucleation and crystallization was observed via optical microscopy. By introducing polyacrylic acid to the systems, positively charged protonated nitrogen and negatively charged carboxylate ions were produced by reaction between the amino group in chitosan and the carboxyl group in polyacrylic acid, which were detected by ATR‐IR and XPS techniques. These charges induced calcium carbonate nucleation of calcite and vaterite crystals on the chitosan‐film surface. The average size of the vaterite phase was about 15 nm, determined by XRD. The pH of the solution changed from 5.80 to 9.25 during the crystallization; moreover, the crystals showed spherical morphology, which consisted of a large number of small particles with a diameter of about 0.2 μm. © 1995 John Wiley & Sons, Inc.
Hydrogenation of 1,3‐butadiene and isoprene prepolymers having carboxyl end groups
Authors: Luo Yanming
Published: April 2003

The hydrogenations of butadiene and isoprene prepolymers having carboxyl and cyano end groups were investigated by two methods: Heterogenous hydrogenations were carried out at 45°C and 50 psi of hydrogen pressure with palladium on carbonate as catalyst. The best degree of saturation and carboxyl retention were 95 and 79% for butadiene prepolymers and 84 and 95% for an isoprene prepolymers, respectively. Dimide reduction was made in xylene at 130–140°C and normal pressure with p‐toluenesulfonylhydrazide (TSH) as the diimide source. A nearly 100% degree of saturation for butadiene prepolymers and 91% for isoprene prepolymers were achieved. The effects of reaction conditions on the degree of saturation and the carboxyl retention, calculation of molecular weight before and after hydrogenation based on H‐NMR spectral data, and diimide reduction with TSH are discussed. © 1995 John Wiley & Sons, Inc.
The effect of transcrystallinity on the transverse mechanical properties of single‐polymer polyethylene composites
Authors: Teishev Albert , Marom Gad
Published: April 2003

The microstructure of polyethylene (PE)/PE composites, consisting of the high‐density PE (HDPE) matrix and ultrahigh molecular‐weight PE (UHMWPE) fibers, was investigated. Single‐fiber composites were prepared and analyzed in a hot‐stage crystallization unit attached to a polarizing microscope, aiming to find out how the conditions of crystallization affected the transcrystallinity (tc) growth at the fiber‐matrix interface. Thermal treatments leading to two extreme microstructures, of either maximum or minimum thickness of the transcrystalline zone, were sought. It was found that a uniform transcrystalline layer was developed on the UHMWPE fiber from the HDPE melt under isothermal conditions, whereas rapid cooling from the melt prevented the generation of tc. The mechanical properties of unidirectional composite laminae either with or without the transcrystalline zone were measured. A comparison of the transverse strength predicted by theoretical models with the experimental values revealed good interfacial adhesion in the PE/PE system. It was shown that the tc growth had a negligible effect on the composite mechanical properties in the longitudinal direction, whereas it resulted in a 50% decrease of the transverse tensile strength and strain to failure. Scanning electron microscopy attributed that observation to premature brittle failure at tc/tc contact regions. © 1995 John Wiley & Sons, Inc.
A macrokinetic approach to crystallization applied to a new thermoplastic polyimide (New TPI) as a model polymer
Authors: Torre Luigi , Maffezzoli Alfonso , Kenny José M.
Published: April 2003

The application of a new macrokinetic approach to polymer crystallization is applied in this work to a new thermoplastic polyimide (New TPI) recently developed as a matrix of advanced polymer matrix composites. The slow crystallization kinetics presented by New TPI in the entire range between the glass‐transition temperature and the melting point makes TPI an excellent model polymer for testing crystallization models. In the approach presented here the variation of the induction time with the temperature is included in the Nakamura model for nonisothermal crystallization, and a simplified expression of the kinetic constant as a function of the temperature is adopted. The proposed model is verified through a comparison with a complete set of experimental data, ranging from the melting point to the glass‐transition temperature of the polymer, obtained in isothermal and nonisothermal conditions. Moreover phase transformation diagrams (TTT and CCT plots) are presented, providing a fundamental tool for understanding the crystallization behavior of semicrystalline matrices and to determine the more appropriate processing conditions. © 1995 John Wiley & Sons, Inc.
Effect of coupling agents on thermal and electrical properties of mica/epoxy composites
Authors: Bajaj Pushpa , Jha N. K. , Kumar Anand
Published: April 2003

The influence of 3‐aminopropyltriethoxysilane, 3‐glycidyloxypropyltrimethoxysilane, and neoalkoxytric(dioctyl pyrophosphato)zirconate on thermal expansion behavior, dielectric strength, and arc resistance of mica/epoxy composites has been investigated. The addition of mica up to 30% resulted in the reduction of thermal expansion with respect to neat resin. However, the coefficient of linear thermal expansion of 30% mica treated with aminosilane was the least among the various coupling agent‐coated filler/epoxy composites. Mica (30%)/epoxy composites showed the highest dielectric strength values (26 kV/mm), but the highest arc resistance was obtained in zirconate‐treated mica (30%)/epoxy composite. © 1995 John Wiley & Sons, Inc.
Modified free‐volume model for pervaporation of water/ethanol mixtures through membranes containing hydrophilic groups or ions
Authors: Kim Hyo Jin , Jo Won Ho , Kang Yong Soo
Published: April 2003

The free‐volume model for pervaporation has been modified by considering the polar path, in order to apply the model to membranes containing hydrophilic groups. The free‐volume parameters were determined by inverse gas chromatography. For the polyacrylonitrile (PAN) membrane, the transport mechanism could be analyzed only by the free‐volume model; however, for a membrane containing a hydrophilic moiety, the transport properties could be interpreted by the modified model. In water/ethanol mixtures, ethanol transports through the membrane matrix, while water permeates through the polar pathways consisting of polar groups or ions and water molecules as well as through the membrane matrix. © 1995 John Wiley & Sons, Inc.
Synthesis and evaluation of some functionalized difuran diesters as plasticizers for PVC
Authors: Sanderson R. D. , Schneider D. F. , Schreuder I.
Published: April 2003

Butyl, hexyl, and 2‐ethylhexyl diesters of 1,1‐bis(5‐carboxyl‐2‐furyl)‐2,2‐dichloroethene, hexyl and 2‐ethylhexyl diesters of 1,1‐bis(5‐carboxyl‐2‐furyl) ketone, and the hexyl diester of 1,1‐bis(5‐carboxyl‐2‐furyl)methane were synthesized from furfural and evaluated for their plasticizing abilities toward PVC, by the application of dynamic mechanical thermal analysis and [di(2‐ethylhexyl) phthalate] as a standard of reference. © 1995 John Wiley & Sons, Inc.
Permeation of solutes through chemically modified chitosan membranes
Authors: Seo Toshihiro , Ohtake Hitoshi , Unishi Terunobu , Iijima Toshiro
Published: April 2003

Chemically and mechanically stable chitosan and N‐acylchitosan were prepared. N‐Octanoylchitosan gives the pronounced decrease of water content, whereas N‐benzoylchitosan keeps a higher content of water. The equilibrium sorption of various sodium salts was determined and is explained by a dual mechanism, consisting of partition and Langmuir sorption. The characteristics of the membrances and the size of the salt anions clearly influence permeability as well as sorption. Permeation behavior was interpreted by the Teorell‐Meyer‐Sievers (TMS) theorem. The mobility of anions decreases with Stokes radius, decreasing in the order chitosan > N‐benzoylchitosan > N‐octanoylchitosan, indicating the effect of the polymer chain molecules, especially a steric obstruction effect on the ion transportation through the membranes. The introduction of the N‐acylated hydrophobic group to the charged chitosan membranes appears to enhance permselectivity. © 1995 John Wiley & Sons, Inc.
Analysis and experimental study of gas penetration in a gas‐assisted injection‐molded spiral tube
Authors: Chen S. C. , Hsu K. F. , Hsu K. S.
Published: April 2003

Characteristics of gas penetration and polymer melt flow in gas‐assisted injection molded spiral tubes was investigated by simulations and experiments. Distribution of the skin melt thickness along the gas flow direction was measured, and gas penetration in the primary and secondary stages was identified. An algorithm based on the control‐volume/tiniteelement method combined with a particle‐tracing scheme using a dual‐filling‐parameter technique is utilized to predict the advancements of both melt front and gas from during the molding process. The simulated distribution of gas penetration shows reasonably good coincidence with experimental observations. © 1995 John Wiley & Sons, Inc.
Sorption and interactions of gases in polyaniline powders of different doping levels
Authors: Rebattet L. , Escoubes M. , Genies E. , Pineri M.
Published: April 2003

Sorption of different gases (N2, O2, CH4, and CO2) were performed on as‐synthesized polyemeraldine base, on HCl 4M doped, on NH4OH 1M undoped, and on HCl 10−2M redoped powders. In the pressure range examined (100–700 torr), linear sorption isotherms were observed for N2 and correspond to an ordinary dissolution in Henry's law state. Concerning O2, CH4, and CO2, nonlinear isotherms were evidenced and could be described by the dualmode sorption mechanism proposed for glassy polymers, which consists of the combination of a Henry's type dissolution with a Langmuir sorption in unrelaxed gaps between macromolecular chains. Specific interactions between polyaniline (PANi) and O2, CH4, and CO2, were studied. Gas permeation experiments were performed by using different upstream pressures, P1, and have confirmed the dissolution of Henry's type for N2 and the dualmode mechanism for O2 and CO2. From the fits of the sorption isotherms, gas solubilities of N2, O2, CH4, and CO2 were calculated for three different gas pressures and analyzed in terms of gas separation for permeation experiments. © 1995 John Wiley & Sons, Inc.
Irradiation effects on electrical properties of cellulose nitrate
Authors: Amin M. , Darwish K. A. , Mounir M. , Elez M. Abu
Published: April 2003

Cellulose nitrate (CA‐80‐15) films were exposed to UV and neutron irradiations. An increase of the electrical conductivity was observed. The values of the activation energy diminish with irradiation from 0.42 to 0.15 eV for UV and to 0.31 eV for neutron irradiation. A sharp increase in the current was observed after exposing CA‐80‐15 samples to fission neutron fluences of 1*107 n/cm2. The electrical conduction in cellulose nitrate is governed by the Shottky mechanism. The value of the electron affinity of the polymer used is 4.46 eV. This value is increased after both types of irradiation. The dielectric permittivity (ε′) of the above samples together with the dielectric loss factor (ε″) were measured over a range of temperatures (293–403 K) at fixed frequencies (1*103, 1*104, and 1*105Hz). Three neutron exposures (ϕ = 1*105, 1*106, and 1*107 n/cm2) were used. The obtained results made it possible to determine a complete set of conduction parameters including dielectric susceptibility χ, ac conductivity αac, and temperature coefficient of permittivity TC. © 1995 John Wiley & Sons, Inc.
Propene polymerization with MgCl2‐supported TiCl4/dioctylphthalate catalyst. II. Effects of polymerization conditions on the microstructure of isotactic polymer
Authors: Yang Chun B. , Hsu Cheng C.
Published: April 2003

Propene was polymerized over the MgCl2‐supported TiCl4/dioctylphthalate catalyst in heptane. Polymer products obtained under different polymerization conditions were separated into isotactic and atactic polypropenes by the extraction of boiling n‐heptane. The effects of polymerization time, cocatalyst type, cocatalyst/catalyst ratio, polymerization temperature, and external base/cocatalyst ratio on the isotactic triad of the isotactic portion of polypropene were investigated 2,2,6,6‐Tetramethyl piperidine (TMPIP), dimethoxy diphenyl silane (DMDPS), and t‐butylmethyl ether (TBME) were employed as the external Lewis base. High concentrations of the first two bases caused a decrease in isotactic triads in the isotactic polymer, while TBME showed no significant effects. The difference can be attributed to the different roles these external bases play in polymerization. © 1995 John Wiley & Sons, Inc.
Gas separation properties of isophorone‐based polyarylates
Authors: Jager Jan , Hendriks Anton J. J.
Published: April 2003

The oxygen and nitrogen permeability coefficients and oxygen/nitrogen selectivities of a series of isophorone‐based polyarylates have been measured. The monomeric bisphenols used in this study are easily accessible in two steps from cheap, commercially available, isophorone (3,5,5‐trimethyl‐2‐cyclohexen‐1‐one). The corresponding polyarylates can easily be prepared in high yield by means of the well‐known interfacial polycondensation route. The effect of substituents (CH3, Cl, or Br) on all positions ortho to both hydroxyl groups in the bisphenol and the influence of the terephthalic acid/isophthalic acid molar ratio in the polyarylate on the oxygen/nitrogen separation performance have been studied in detail. It has been found that the polyarylate with four bromine substituents displays a significantly increased oxygen and nitrogen permeability coefficient, combined with a high oxygen/nitrogen selectivity, relative to conventional polyarylates. Obviously, the bulky 3,3,5‐trimethylcyclohexylidene moiety in the bisphenol has structural features that hinder an effcient chain packing and reduce polymer segmental mobility. A further improvement in the gas permeability of these polyarylates can be achieved when the bulky t‐butyl group is introduced on the 5 position in isophthalic acid. For example, the polyarylate prepared from the isophorone‐based bisphenol with four methyl substituents and 5‐t‐butylisophthalic acid is characterized by an oxygen permeability coefficient of 34.7 Barrer! © 1995 John Wiley & Sons, Inc.
Graft copolymerization of acrylamide on cotton cellulose in a limited aqueous system following pretreatment technique
Authors: Ghosh P. , Dev D. , Samanta A. K.
Published: April 2003

Graft copolymerization of acrylamide on cotton (dialdelyde cellulose, DAC) fibers and fabrics was studied in a limited aqueous system using K2S2O8 as the initiator. Grafting parameters under different sets of conditions were determined and the mechanism of graft copolymerization discussed. Optimum conditions for grafting were established and the effect of polyacrylamide grafting on tenacity, modulus, breaking elongation, and stiffness of the cotton (DAC) fabrics and on their dyeability and moisture regain properties were also studied; 9–10% grafting of polyacrylamide on (DAC) fabric at pH 7–10 imparts an improved balance in its mechanical and other properties. © 1995 John Wiley & Sons, Inc.
Semianalytical solution of irreversible anionic polymerization with unequal reactivity in batch reactors
Authors: Sailaja R. R. N. , Kumar Anil
Published: April 2003

Anionic polymerization with unequal reactivity in batch reactors is a nonlinear problem, and in order to determine the rate constants using the experimental molecular weight distribution (MWD) and conversion vs. time of polymerization, the simulation equations need to be solved repeatedly. In this work, we evolved an efficient algorithm in which the experimental MWD yields the reactivity ratio directly while conversion data give the values of all rate constants. For doing this, we proposed a series solution for the reacting species in terms of monomer conversion. A technique similar to the finite element method for boundary problems is used to divide the conversion into subdomains. The size of these steps is decided by a convergence criterion and results were determined at the end of the conversion domain through sequential computation. The scheme can be implemented on a personal computer and is considerably faster and more efficient. We used experimental data from the literature and demonstrated our technique of evaluating the rate constants. © 1995 John Wiley & Sons, Inc.
Time‐dependent permeation of carbon dioxide through a polyimide membrane above the plasticization pressure
Authors: Wessling M. , Huisman I. , Boomgaard Th. v. d. , Smolders C. A.
Published: April 2003

The time‐dependent permeation behavior of a glassy polyimide is studied above and below the plasticization pressure with carbon dioxide as the permeating gas. The work particularly focuses on the quantification of the slow increase in permeability at feed pressures above the plasticization pressure. Significant differences in permeation behavior were found for membranes with and without permeation history. Introducing the quantity “conditioning time” allows one to compare the results obtained for membranes with different permeation history. The concept of conditioning time furthermore allows one to quantify the aging of a membrane plasticized during previous permeation. © 1995 John Wiley & Sons, Inc.
Structural and thermal behavior of PC/PBT blends
Authors: Mishra S. P. , Venkidusamy P.
Published: April 2003

Blends of polycarbonate (PC) with poly(butylene terphthalate) (PBT) were characterized using density measurements, DSC, IR, and TGA. Addition of PBT increases the density values of blends linearly. All the blends show a single glass transition temperature, indicating the miscibility of the two polymers in the amorphous phase. With more than 6% addition of PBT to PC, PBT crystallizes as per its own crystal structure. The addition of 4% PBT to PC improves the thermal stability at higher temperature than does pure PC. IR studies shows that addition of PBT improves the intermolecular forces in PC, in particular, on the endgroup and the CCH3 and CO groups as indicated in the frequencies 1020, 1370, and 1770–1790 cm−1. © 1995 John Wiley & Sons, Inc.
Expression of the type III TGFβ receptor during chick organogenesis
Authors: Olivey Harold E. , Barnett Joey V. , Ridley Bettye D.
Published: April 2003

Transforming growth factor β (TGFβ) is a regulator of embryonic development. The role of specific TGFβ receptors is emerging, and a unique role for the type III TGFβ receptor (TBRIII) has been suggested. We report the pattern of TBRIII expression in chicken embryos from 2 to 14 days in ovo. Anat Rec Part A 272A:383–387, 2003. © 2003 Wiley‐Liss, Inc.
Optimization of information searching efficiency in Web space by using probability of target location
Authors: Naito Seiichiro , Kobayashi Aki , Yamaoka Katsunori , Sakai Yoshinori
Published: April 2003

With the spreading use of the Web, there are increasing opportunities for information retrieval from the Internet. It is thus desirable to establish a method that can efficiently locate information required by a user from Web space, over which diverse information is scattered. This paper discusses a search scheme through links in Web space where the target search efficiency is maximized by utilizing the knowledge owned by the links. First, assuming that the probability that the target is present can be estimated from knowledge in Web pages, the estimation procedure is discussed. Then, the search process used to trace the links in Web space is modeled by a tree structure. Two problems are defined, namely, minimization of the retrieval cost and maximization of the number of retrieved pages. For each of these, an efficient search procedure is proposed. Lastly, the performance of the method is analyzed. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(10): 45–54, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10048
A Kalman filter using texture for noise reduction in SAR images
Authors: Tsuchida Masayoshi , Haseyama Miki , Kitajima Hideo
Published: April 2003

In this paper, we propose a noise reduction method for synthetic aperture radar (SAR) images that uses a Kalman filter. The noise in SAR images is primarily generated by speckle and appears as salt‐and‐pepper noise. Speckle noise is known to have the multiplicative statistical property, but this property may not hold depending on the region. Consequently, adequate noise removal is difficult. In radar, the expected values of the backscattered waves change due to the type of reflecting object. The proposed method segments an image into several regions based on the texture and varies the parameters in Kalman filtering in response to the region. By varying the parameters, the processing can account for the noise generated primarily by speckle in actual SAR images and the changes in the statistical properties of the backscattered waves. In this paper, we apply the proposed method to synthetic test images and to actual SAR images to quantitatively evaluate the noise reduction and present the results. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(10): 21–32, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10065
Strain‐specific mammary proliferative lesion development following lifetime oral administration of ochratoxin A in DA and Lewis rats
Authors: Son Woo‐Chan , Kamino Kenji , Lee Yong‐Soon , Kang Kyung‐Sun
Published: April 2003

OTA, a potent nephrotoxin in several species, is a renal carcinogen in animals and is implicated in the etiology of BEN. The NTP classified OTA as having clear evidence of carcinogenic activity, based on uncommon tubular adenomas and tubular cell carcinomas of the kidney and multiple fibroadenomas of the mammary gland, seen in the rat. As shown previously (Castegnaro et al., Int J Cancer 1998;77:70–5), induction of renal tumors by OTA is sex‐ and strain‐specific in DA and Lewis rats, with DA males being most responsive and DA females being resistant; however, that report was confined to the kidney and urinary tract. To obtain OTA‐induced tumorigenic information in rats, we administered OTA (0.4 mg/kg) by oral gavage to both DA and Lewis rats for their lifetimes and extended the investigation to complete histopathology of all tissues and organs. We also observed the characteristic renal tumor that is highly strain‐ and sex‐specific, and there were increased incidences of proliferative mammary lesions in Lewis rats but not in DA rats, indicating that these were also strain‐specific. In view of the NTP report of OTA treatment‐related mammary fibroadenoma in F344 rats, we observed increased mammary proliferative lesions in Lewis rats but not in DA rats. Our results suggest that OTA may play some role in mammary tumor development in some rat strains. © 2003 Wiley‐Liss, Inc.
Intake of fruits, vegetables and selected micronutrients in relation to the risk of breast cancer
Authors: Malin Alecia S. , Qi Dai , Shu Xiao‐Ou , Gao Yu‐Tang , Friedmann Janet M. , Jin Fan , Zheng Wei
Published: April 2003

High fruit and vegetable intake has been linked with a reduced risk of breast cancer, but evidence is not consistent. We investigated the associations of breast cancer risk with vegetables, fruits and related micronutrient intake in a population‐based case–control study among Chinese women in Shanghai, where dietary patterns differ substantially from other study populations. Included in the study were 1,459 incident breast cancer cases and 1,556 frequency‐matched controls. Usual dietary habits were assessed by in‐person interviews. Logistic regression was used to compute adjusted odds ratios (ORs) and 95% confidence intervals (CIs) to measure strength of the associations. There was no association between breast cancer risk and total vegetable intake. The risk of breast cancer declined, however, with increasing intake of dark yellow‐orange vegetables (trend test, p = 0.02), Chinese white turnips (trend test, p ≤ 0.001), and certain dark green vegetables (trend test, p ≤ 0.001) with adjusted OR in the highest quintile being 0.79 (95% CI = 0.60–0.98), 0.67 (95% CI = 0.53–0.85) and 0.65 (95% CI = 0.51–0.83) respectively. Intake of fruits, except watermelons and apples, was inversely associated with breast cancer risk (p‐values for trend tests ≤0.05). Our study suggests that high intake of certain vegetables and fruits may be associated with a reduced risk of breast cancer. © 2003 Wiley‐Liss, Inc.
Kinetics of substitution of aqua ligands from cis‐diaqua (ethylenediamine)platinum(II) perchlorate by L‐asparagine in aqueous medium
Authors: Bera Sujit K. , Chandra Swapan K. , De Gauri S.
Published: April 2003

The kinetics of the interaction of L‐asparagine with [Pt(ethylenediamine)(H2O)2]2+ have been studied spectrophotometrically as a function of [Pt(ethylenediamine)(H2O)22+], [L‐asparagine], and temperature at pH 4.0, where the substrate complex exists predominantly as the diaqua species and L‐asparagine as the zwitterion. The substitution reaction shows two consecutive steps: the first step is the ligand‐assisted anation and the second one is the chelation step. Activation parameters for both the steps have been calculated using Eyring equation. The low ΔH1≠ (43.59 ± 0.96 kJ mol−1) and large negative values of ΔS1≠ (−116.98 ± 2.9 J K−1 mol−1) as well as ΔH2≠ (33.78 ± 0.51 kJ mol−1) and ΔS2≠ (−221.43 ± 1.57 J K−1 mol−1) indicate an associative mode of activation for both the aqua ligand substitution processes. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 252–259, 2003
Versuche zur darstellung von polymeren kieselsäureestern
Authors: Staudinger von Hermann , Hahn Walter
Published: April 2003

Es wurden Versuche zur Herstellung von linearen Polymeren aus Dialkoxy‐ bzw. Diaryloxy‐dichlorsilanen und zweiwertigen Alkoholen ausgeführt. Je nach Art des verwendeten Alkohols bilden sich ‐ in einigen Fällen nebeneinander ‐ cyclische monomere oder polymere Verbindungen, die jedoch nicht sehr hochmolekular sind.

Die aus Diphenoxy‐dichlorsilan erhaltenen Ester verseifen schon an feuchter Luft leicht. Beständiger sind die durch Kondensation von Dicyclohexoxy‐dichlorsilan mit Diolen erhaltenen Produkte. Hier ist vor allem der Terpinester gegen Wasser relativ gut beständig.
Über die bildung von spirocyclischen kieselsäureestern aus siliciumtetrachlorid und zweiwertigen alkoholen
Authors: Hahn von Walter
Published: April 2003

Durch Umsetzung von verschiedenen zweiwertigen Alkoholen mit Siliciumtetrachlorid wurden spirocyclische Ester der Orthokieselsäure mit 5 er‐, 6 er‐, 7 er‐ und 8 er‐ Ringen erhalten. Die Reaktion erfolgt mit 1,2‐ditertiären Glykolen sehr leicht; bei 1,3‐, 1,4‐ und 1,5‐Diolen wird in stark verdünnter Lösung gearbeitet. Mit Glykol selbst und höheren als 1,5‐Diolen wurden vernetzte Produkte erhalten.
Über die pharmakologie wasserlöslicher polysaccharide und ihrer derivate in abhängigkeit von molekülgröße, molekülgestalt und art der substituenten
Authors: Husemann von E. , Lötterle R. , Wiedersheim M. , Hertlein W.
Published: April 2003

Es wurde die Wirkung wasserlöslicher Polysaccharide und ihrer Derivate auf das weiße Blutbild, die Körpertemperatur und die Blutsenkungsgeschwindigkeit von Kaninchen untersucht, um Zusammenhänge zwischen Molekülgröße, Molekülgestalt und elektrochemischen Eigenschaften aufzufinden. Dabei wurden folgende Ergebnisse erhalten:

Homöopolare unverzweigte Substanzen rufen eine Leukopenie hervor und steigern die Körpertemperatur. Bei erhöhter Kettenlänge nimmt die Dauer der Leukopenie und die Höhe des Fiebers zu. Die Blutsenkungsgeschwindigkeit wird oberhalb eines Polymerisationsgrades von 200 beschleunigt, unterhalb dieses Wertes gehemmt.

Homöopolare verzweigte Substanzen haben keinen Einfluß auf Blutbild und Körpertemperatur. Auf die Blutsenkungsgeschwindigkeit wirken sie entsprechend der Länge der Moleküle unabhängig vom Molekulargewicht.

Carboxylhaltige unverzweigte Substanzen beeinflussen weder Blutbild noch Körpertemperatur, noch Blutsenkungsgeschwindigkeit.

Unverzweigte Polysaccharidschwefelsäureester bewirken unabhängig vom Molekulargewicht eine Leukocytose. Die Körpertemperatur wird nicht beeinflußt. Die Blutsenkungsgeschwindigkeit wird verlangsamt.
Viscosities of dilute solutions of rubber and chlorinated rubbers
Authors: Kapadia Faridum H.
Published: April 2003

Viscosity studies of solutions in carbon tetrachloride of sol, gel, whole rubber and chlorinated rubber, show an anomalous increase in viscosity at high dilutions. In certain cases, this increase is followed by a decrease in ηsp/c, giving intercepts at much lower values than ordinarily obtained by extrapolation in viscosity studies.
Über Lösungen von Cellulose in Tetraäthylammoniumhydroxyd
Authors: Krässig Von H. , Siefert E.
Published: April 2003

Durch einen Vergleich der Viskositätszahlen verschieden hochmolekularer Cellulosen in Kupferhydroxydammoniak und in Tetraäthylammoniumhydroxyd‐Wasserlösungen wird gezeigt, daß der Lösungszustand in beiden Lösungsmitteln der gleiche ist.

Für die Beziehung der Molekülgröße und der Viskosität von Cellulose in Tetraäthylammoniumhydroxyd‐Wasser gilt in gleicher Weise wie für die Lösungen in Kupferhydroxyd‐Ammoniak das Staudinger sche Viskositätsgesetz. Die Km‐Konstante des Tetraäthylammoniumhydroxyd‐Wassers als Lösungsmittel wurde zu etwa 5,8·10−4 bestimmt.

Die Lösungen sind sehr stabil gegenüber Sauerstoff und Luft. Man kann aus ihnen Cellulose ohne Schutzmaßnahmen für Sauerstoffausschluß umfällen.

Cellulosen höheren Polymerisationsgrades als etwa 1500 lösen sich in Tetraäthylammoniumhydroxyd‐Wasser nicht mehr vollständig.
Interdiffusion between rubber and solvents under static conditions
Authors: Pande J. B. , Ramakrishnan C. S. , Raghunath D. , Kapur S. L.
Published: April 2003

Experimental evidence is presented to show that the dissolution of rubber in a solvent is a diffusion process in which both components interdiffuse into one another. The influence of light in such process has been demonstrated. Replacement of air by nitrogen in the process of diffusion has also been studied.