bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer simulation of high‐speed spinning of PET
Authors: Denton Jeffrey S. , Cuculo John A. , Tucker Paul A.
Published: April 2003

An interactive computer simulation of the steady‐state melt spinning of poly(ethylene terephthalate) was developed based upon a combination of physical laws and empirical relationships. The simulation incorporates crystallization effects which makes it valid for a wide range of take‐up speeds. Modifications to the conventional threadline that allow judicious control over the threadline dynamics were modeled and included in the simulation for exploration of the effects of these perturbations. The modifications include quenching and on‐line zone heating. The simulation was verified using experimental measurements of threadline diameter, velocity, and temperature at 3000, 4000, 5000, and 6000 m/min take‐up. Off‐line measurements of crystallinity and birefringence were also compared with the values calculated by the simulation at these speeds. © 1995 John Wiley & Sons, Inc.
The quantitative analysis of fluorocarbon polymer finishes on wool by FT‐IR spectroscopy
Authors: Church Jeffrey S. , Evans David J.
Published: April 2003

Two contrasting infrared spectroscopic techniques, Attenuated Total Reflectance (ATR) and PhotoAcoustic Spectroscopy (PAS), have been investigated as means for the determination of fluorocarbon polymer finishes on wool fabric. Based on the experimental conditions used, the results of the PAS method are more characteristic of the bulk sample, while the ATR results are more surface specific. Linear calibrations between polymer addon, as determined by total fluorine analysis, and the absorbance of the CF stretching bands of the normalized spectral data were obtained for a typical commercial fluorocarbon polymer. The correlation obtained for the PAS method was found to be significantly better than that of the ATR method. The lower limit of detection of fluorocarbon polymers on wool using the PAS technique was 0.25% on the weight of the wool (oww). In contrast, fluorocarbon polymer add‐ons as low as 0.125% oww (approximating monolayer coverage) could be analyzed using the ATR method. At high levels of add‐on, the ATR calibration deviated from linearity. This can be attributed to the distribution of fluorocarbon polymer on the surface of the fiber, in particular, the build up of polymer on the cuticle cell edge regions. The quantitative methods developed are used to help access the effects of wear and the subsequent heating of fluorocarbon polymer‐treated fabric samples. © 1995 John Wiley & Sons, Inc.
Effect of doping treatment on gas transport properties and on separation factors of polyaniline memebranes
Authors: Rebattet L. , Escoubes M. , Genies E. , Pineri M.
Published: April 2003

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

This paper presents a study of the reactions involved in stabilization of polyacrylonitrile (PAN) through the effect of various experimental variables on the differential scanning calorimetry (DSC) exotherm and thermogravimetric measurements coupled with Fourier transform infrared (FTIR) spectroscopy, i.e., DSC‐FTIR and TG‐FTIR. The experimental variables used were the environment of heat treatment (viz. oxidative and inert) and in corporation of an acidic comonomer (viz. itaconic acid). The essential findings include the broadening of the exotherm in an air atmosphere over that in a nitrogen (i.e., inert) atmosphere. This broadening of the exotherm was further enhanced in the presence of the acidic comonomer. Furthermore, the exotherm revealed a doublet character with greater separation of the peaks in case of the copolymer than the homopolymer. Possible explanations of these observations are discussed. © 1995 John Wiley & Sons, Inc.
Preparation of high‐strength/high‐modulus regenerated cellulose fibers from lyotropic mesophases
Authors: Gilbert R. D. , Hu Xuechao , Fornes R. E.
Published: April 2003

Cellulose triacetate (CTA) fibers were spun from a 35% (w/v) solution of CTA (molecular weight, 95,000) in trifluoroacetic acid (TFA)/CH2CL2 (60/40, v/v) using laboratory‐scale spinning equipment, an air gap, and cold MeOH as the coagulant. The resulting fibers, of large diameter (ca. 80 μm) were saponified with a variety of reagents. The regenerated cellulose fibers had tenacities and moduli as high as 1.6 and 50 GPa, respectively. The fiber properties did not show a dependence on which cellulose polymorph was present. It is suggestes that for highly oriented fibers, the cellulose molecular weight is the primary parameter that determines the strength and modulus. This emphasizes the advantages of using a lyotropic cellulosic mesophase which permits relatively low solution viscosities at high concentrations and high polymer molecular weights. © 1995 John Wiley & Sons, Inc.
Viscoelastic and elastic behavior of polypropylene and ethylene copolymer blends
Authors: Cassagnau P. , Espinasse I. , Michel A.
Published: April 2003

Thermorheological properties of an incompatible polymer blend of polypropylene inclusions dispersed in a ethylene copolymer matrix were discussed from the emulsion model developed by Palierne. Due to the different rheological behaviors with temperature of the two phases, such a system proved to be a judicious blend in order to consider the special cases of the model applications: (1) the two phases are viscoelastic liquids, (2) the dispersed phase is a solid elastic assimilated to rigid spheres in comparison with viscoelastic liquid behavior of the matrix, and (3) the two phases are elastic solids. At low frequencies, the rheological behavior of the blend was not correctly predicted by the model. So interactions other than hydrodynamics can exist in the intrafacial region, and physical entanglements between the chains of the two constituents leading to topological interactions may be assumed at the interphase. © 1995 John Wiley & Sons, Inc.
Synthesis and properties of methacrylonitrile–EPDM–2–vinylnaphthalene graft terpolymer
Authors: Lee Seung Wook , Park Duck Jei , Ha Chang Sik , Cho Won Jei
Published: April 2003

The graft terpolymer of methacrylonitrile (MAN) and 2‐vinylnaphthalene (2‐VN) onto ethylene‐propylene‐diene terpolymer (EPDM) was synthesized in toluene using benzoyl peroxide (BPO) as an initiator. The effects of EPDM content, mole ratio of 2‐VN to MAN, reaction time, reaction temperature, and initiator concentration on the graft copolymerization were examined. The synthesized graft terpolymer was identified by IR and 1H‐NMR spectroscopies. The light resistance, thermal stability, molecular weight, and tensile properties of the graft terpolymer were investigated by Fade‐o‐meter, thermogravimetric analysis, gel permeation chromatography (GPC), and a universal tensile machine (UTM). It was found that the light resistance and heat resistance as well as the tensile strength of the graft terpolymer are considerably better than those of the acrylonitrile‐butadiene‐styrene (ABS) terpolymer. © 1995 John Wiley & Sons, Inc.
Preparation and properties of new polycyclic aliphatic polyamides base on diamantane
Authors: Chern Yaw‐Terng , Fang Jea‐Shih , Chung Meng‐An
Published: April 2003

A series of novel polycyclic aliphatic polyamides was synthesized by direct polycondensation of the 1,6‐diamantane dicarboxylic acid with various alicyclic diamines in N‐methyl–2–pyrrolidone (NMP) containing lithium chloride, using triphenyl phosphite and pyridine as a condensing agent. The polyamides had inherent viscosities of 0.33–0.49 dL/g. The glass transition temperatures of the these polyamides were in the range of 200–220°C, and the 5% weight loss temperatures were in the range were 290–319°C in nitrogen. © 1995 John Wiley & Sons, Inc.
Preparation of polyethyleneglycol (PEG) and cellulose acetate (CA) blend membranes and their gas permeabilities
Authors: Li Jintong , Nagai Kazukiyo , Nakagawa Tsutomu , Wang Shichang
Published: April 2003

Miscible blend membranes containing 10 wt % PEG of low molecular weight 200, 600, 2000, and 6000, and 10 wt %, 20 wt %, 30 wt %, 40 wt %, 50 wt %, and 60 wt % of molecular weight 20,000 were prepared to investigate the effect of PEG on gas permeabilities and selectivities for CO2 over N2 and CH4. The permeabilities of CO2, H2, O2, CH4, and N2 were measured at temperatures from 30 to 80°C and pressures from 20 cmHg to 76 cmHg using a manometric permeation apparatus. It was determined that the blend membrane, which contained 10% PEG 20,000, exhibited higher permeability for CO2 and higher permselectivity for CO2 over N2 and CH4 than those of the membranes that contained 10% PEG of the molecular weight ranging from 200 to 6000. The high PEG 20,000 content blend membranes showed remarkable permeation properties such that the permeability coefficients of CO2 and the ideal separation factors for CO2 over N2 reached above 200 barrer and 22, respectively, at 70°C and 20 cmHg. Based on the data of gas permeability coefficients, time lags, and characterization of the membranes, it is proposed that the apparent solubility coefficients of all CA and PEG blend membranes for CO2 were lower than those of the CA membrane. However, almost all of the blend membranes containing PEG 20,000 showed higher apparent diffusivity coefficients for CO2, resulting in higher permeability coefficients of CO2 than those of the CA membrane. It is attributed to the high diffusivity selectivities of CA and PEG 20,000 blend membranes that their ideal separation factors for CO2 over N2 were higher than those of the CA membrane in the temperature range from 50 to 80°C, even though the ideal separation factors of all CA and PEG blend membranes for CO2 over CH4 became lower than those of the CA membrane over nearly the full temperature range from 30 to 80°C. © 1995 John Wiley & Sons, Inc.
Swelling characteristics of block order networks prepared by styrene‐ethylene/butylene ABA triblock copolymer and styrene homopolymer binary blends
Authors: Konstantakopoulos I. C. , Valkanas G. N.
Published: April 2003

Mixed networks based on polystyrene (PS) and styrene‐ethylene/butylene triblock copolymer (SEBS) binary blends were synthesized via a postpolymerization Friedel‐Crafts‐type reaction employing styrene units and a bis‐chloromethylated crosslinking agent. The swelling behavior of the produced gels was studied in relation to network densty, SEBS/PS mass ratio, and solubility parameter of the swelling media, in a range of aliphatic, chlorinated, and aromatic solvents. Swelling characteristics of the mixed macronets were found to differ markedly from those of pure homopolymer gels. Selective swelling was observed in three different regions in respect to the solvent solubility parameter, in contrast to pure PS networks where adsorption was favored in a single region of solvents. This phenomenon was found to depend primarily on the SEBS/PS constitution of gels, while the solvent holding capacity depended directly on the crosslinking density. © 1995 John Wiley & Sons, Inc.
Chemical etching of polyimide film
Authors: Lian Syh‐Ming , Chen Ker‐Ming , Lee Rong‐Jer , Pan Jing‐Pin , Hung Aina
Published: April 2003

Chemical etching rates of BPDA/PDA/ODA/BMI polyimide film by an alkaline etching solution with the presence of different kinds of etchants were studied by film‐thickness measurement and UV absorption spectroscopy of dispersible etching residue. The etching rate of polyimide film in alkaline ethylene diamine solution is highest among the etching solutions studied in the present experiment. If an external bias voltage was applied during etching, the etching rate was increased. The effects of temperature, solubility of the etchant, and ultrasonic vibration on etching rate are also discussed. The presence of a radical in the process of etching reveals that the etching reaction is a type of radical chain reaction. © 1995 John Wiley & Sons, Inc.
Miscibility of poly(vinyl acetate) and vinyl acetate‐ethylene copolymers with styrene‐acrylic acid and acrylate‐acrylic acid copolymers
Authors: Bott R. H. , Kuphal J. A. , Robeson L. M. , Sagl D.
Published: April 2003

Poly(vinyl acetate) and vinyl acetate‐ethylene (VAE) copolymers compose one of the more important polymeric materials, widely employed in coating and adhesive applications. A new class of miscible polymer blends involving poly(vinyl acetate) and VAE with styrene‐acrylic acid and acrylate‐acrylic acid copolymers has been found. Experimental windows of miscibility as a function of the ethylene content for VAE copolymers and the acrylic acid content of the acrylate‐acrylic acid copolymers are observed (acrylate = methyl acrylate, ethyl acrylate, n‐butyl acrylate, and 2‐ethylhexyl acrylate). Employing well‐established analog heat of mixing measurements, predicted windows of miscibility were compared with experimental results. Fair qualitative agreement was observed and supported the hypothesis that specific rejection arguments can be employed to explain the observed miscibility. Failure to quantitatively predict miscibility based on the analog heat of mixing measurements may be due to the higher association tendencies of the model compounds relative to acrylic acid units in the high molecular weight polymers. No miscible combinations were found for methyl methacrylate‐acrylic acid copolymers or acrylate‐methacrylic acid copolymers in admixture with poly(vinyl acetate) or the VAE copolymers, thus indicating the sensitivity of phase behavior to minor structural changes. VAE (30 wt % ethylene) copolymers were also noted to be miscible with several polymers previously noted to be miscible with poly(vinyl acetate), namely, poly(vinylidene fluoride), poly(ethylene oxide), and nitrocellulose. © 1995 John Wiley & Sons, Inc.
Comparison of size distribution data from dynamic light scattering and size‐exclusion chromatography
Authors: Mrkviĉková L. , Porsch B. , Sundelöf L.‐O.
Published: April 2003

The intensity‐defined distribution functions of hydrodynamic radii of equivalent spheres, Rh, obtained from dynamic light‐scattering experiments using the CONTIN procedure via the Stokes formula were compared with distributions of gyration radii, Rg, determined by size‐exclusion chromatography. The number‐, weight‐, and intensity‐ (z)‐defined Rg distributions accessible from size‐exclusion chromatography experiments were calculated using the Flory‐Fox relation. Reliable ratios of average radii, Rg/Rh, for linear polystyrenes having narrow, broad, or bimodal molecular weight distributions were obtained in toluene. Care should be taken to utilize properly averaged experimental quantities. For instance, the CONTIN DLS data evaluation procedure yields the z‐average of the inverse of the hydrodynamic radius, 〈1/Rh〉z−1. © 1995 John Wiley & Sons, Inc.
Reactive processing of LLDPEs in corotating intermeshing twin‐screw extruder. I. Effect of peroxide treatment on polymer molecular structure
Authors: Lachtermacher Marly G. , Rudin Alfred
Published: April 2003

Commercial ethylene‐octene linear low‐density polyethylene (LLDPE) polymers were reactively extruded with low levels of 2,5‐dimethyl‐2,5 di(t‐butylperoxy)hexane to modify their molecular structure and processing properties. Peroxide levels were kept low to avoid crosslinking. This article examines the effects of reactive extrusion in a corotating intermeshing extruder. Gel content analyses and examination of extruded thin tapes indicated that the products were gel‐free, but line‐broadening in high‐resolution 13C‐NMR spectra suggested that some crosslinking did occur. Molecular weight distributions were broadened toward higher molecular weights, as expected. SEC estimates of long‐chain branching in reacted polyethylenes were consistent with the results of 13C‐NMR analyses. Under our extrusion conditions, the products contained about one long branch per number‐average molecule. This result and data on changes in carbon‐carbon unsaturation indicate that the major chain extension mechanism is an end‐linking reaction between terminal vinyls or allylic radicals formed at chain ends and secondary radicals. Both types are produced by hydrogen abstraction on the LLDPE. All long branches originated at tertiary branch points. Changes in thermal behavior, as measured by DSC analyses, paralleled those observed by temperature‐rising elution fractionation (TREF). SEC molecular weight measurements and long‐branch determinations by SEC and 13C‐NMR can be used to quantify the effects of peroxide treatment on the molecular structure of polyethylenes. DSC and TREF techniques, however, appear to be more sensitive than are SEC or NMR. Relatively minor variations in the degree of mixing and temperature control during reactive extrusion have noticeable effects on the molecular structures of the peroxide‐treated LLDPEs. © 1995 John Wiley & Sons, Inc.
Continuous vapor phase polymerization of pyrrole. I. Electrically conductive composite fiber of polypyrrole with poly(p‐phenylene terephthalamide)
Authors: Xu Chaochou , Wang Peng , Bi Xiantong
Published: April 2003

Electrically conductive polypyrrole (PPy)/poly(p‐phenylene terephthalamide) (PPTA) composite fibers have been prepared by continuous vapor phase polymerization at a speed of 0.5 ∼ 1.5 m/min. The main parameters have been examined, and the conducting fibers with the best properties of electrical conductivity 0.68 s/cm, tensile strength 2731 N/mm2, and the elongation at break 4.8% were obtained by using FeCl3 · 6H2O as the oxidizing agent. The results of elemental analysis, wide‐angle X‐ray diffraction analysis and SEM of the composite fibers are also reported. © 1995 John Wiley & Sons, Inc.
Sulfur vulcanization of polyisoprene accelerated by benzothiazole derivatives. I. Comparison of sulfur and 2‐mercaptobenzothiazole accelerated reactions
Authors: Gradwell M. H. S. , Mcgill W. J.
Published: April 2003

Polyisoprene compounds with sulfur and with sulfur and 2‐mercaptobenzothiazole (MBT) were vulcanized by heating in a differential scanning calorimeter (DSC) at a programmed rate. The reaction was stopped at various temperatures along the thermogram and the product analyzed by determining the crosslink density and crosslink type, and by determining the amount of extractable curatives and soluble reaction products by high‐performance liquid chromatography. DSC cure curves and plots of crosslink density and extractable sulfur vs. temperature for the unaccelerated and MBT accelerated compounds can be made to coincide by shifting them along the temperature axis. It is suggested that MBT accelerated sulfur vulcanization occurs by the same mechanism as unaccelerated sulfur vulcanization, with SH+ ions from MBT adding across the carbon–carbon double bond, thus increasing the rate at which the reaction is initiated. © 1995 John Wiley & Sons, Inc.
Nitrogen solubilities in low‐density polyethylene at high temperatures and high pressures
Authors: Lee James G. , Flumerfelt Raymond W.
Published: April 2003

An apparatus for the determination of the solubility of gases in polymers at high pressure and high temperature is described. The solubilities of nitrogen in low‐density polyethylene (PE800E) at 394–450 K at pressures between 10 and 125 atm are reported. Empirical correlations are obtained which represent the Flory–Huggins interaction parameter χ, solubility coefficient KH, and activity coefficient of dissolved gas Ω2 as functions of temperature and pressure for the above system. © 1995 John Wiley & Sons, Inc.
Development of poly(vinyl alcohol) hydrogel for waste water cleaning. II. Treatment ofN,N‐dimethylformamide in waste water with poly(vinyl alcohol) gel with immobilized microorganisms
Authors: Okazaki Masaki , Hamada Tosihiro , Fujii Hiroaki , Kusudo Osamu , Mizobe Akio , Matsuzawa Shuji
Published: April 2003

The activated sludge that had been sufficiently cultivated with DMF‐containing waste water was entrapped and immobilized in spherical poly(vinyl alcohol) (PVA) hydrogel particles. Features of numbers and distribution of bacteria in the resultant PVA gel were estimated. The DMF‐decomposing bacteria namedBacillus cereusD‐1 was isolated. Several morphological and physiological responses of the bacteria were revealed. Spherical PVA gel with the DMF‐decomposing bacteria prepared through of freezing and thawing was tested for treatment of DMF‐containing effluent. Test results have shown the ability of stable operation and maintenance at the same capacity of 1 kg/m3/day by both a basic study and a bench plant test. © 1995 John Wiley & Sons, Inc.
Cure and physical properties of thermoplastic modified epoxy resins based on polyethersulfone
Authors: Mackinnon Alexander J. , Jenkins Stephen D. , Mcgrail Patrick T. , Pethrick Richard A.
Published: April 2003

Dielectric, mechanical, thermal, rheological, and electron microscopy measurements are reported for five series of thermoplastic modified amine cured epoxy resin systems. The epoxy and thermoplastic components have been systematically changed to investigate the factors affecting the phase separation process. Data reported cover both changes in the physical properties occurring during cure and also of the final cured matrix. Dielectric data obtained from fully cured materials exhibits a Maxwell–Wagner–Sillers relaxation process characteristic of a phase separated morphology. Correlation of dielectric relaxation and electron microscopy data indicates that the phase structure changes with the thermoplastic content and composition of the epoxy phase. The mechanical properties change significantly at about 20–25% (w/w) of incorporated thermoplastic, coincident with the formation of a cocontinuous phase morphology. © 1995 John Wiley & Sons, Inc.
Electrical behavior of polycarbonate doped with nickel chloride
Authors: Amin M. , Mounir M. , Darwish K. A. , Elez M. Abu
Published: April 2003

The dc electrical conductivity (σ) and permittivity (ε′) of polycarbonate (PC) discs doped with different concentrations of NiCl2 are studied. Both (σ) and (ε′) increase with increasing the concentration of NiCl2, with a maximum value at 30 wt %. The activation energies for pure and doped PC are 0.49 and 0.53 eV, respectively. The increase in the electrical conductivity with increasing NiCl2 concentration is attributed to the formation of chargetransfer complexes (CTC); the increase in ε′ may be due to the rise in the interfacial polarization which results from the increase in boundaries between PC and NiCl2 phases. The currents in PC discs, both pure and doped with NiCl2, in the high‐field region are attributed to space charge limited conduction. The time dependence of conduction current before and after reversal of applied voltage is also investigated. Some parameters such as the density of mobile ions and their drift mobilities are estimated. © 1995 John Wiley & Sons, Inc.
Vascular endothelial growth factor: A regulator of vascular morphogenesis in the Japanese quail embryo
Authors: Finkelstein Eric B. , Poole Thomas J.
Published: April 2003

Experiments in mouse embryos indicate that a critical level of VEGF is required for normal vascular development, as mice lacking a single VEGF allele die at midgestation. Thus VEGF concentration may be a determinant of the size and location of major blood vessels during formation of the primary capillary plexus. Ectopic VEGF delivery was used to examine the effect of VEGF concentration on early vascular patterning in the quail embryo. VEGF was delivered by implanting VEGF‐soaked heparin chromatography beads at three rostral‐caudal locations in embryos with six somite pairs, which allowed us to study the effect of VEGF on different cellular activities. Ectopic VEGF resulted in significant changes in the vascular pattern at three rostral‐caudal levels. Quantitation demonstrated an increased vascularity in the area of the implanted VEGF bead compared to the vascular pattern of embryos with control beads. Areas lateral to the dorsal aortae that are normally avascular became vascularized, and there was an apparent fusion between the dorsal aorta and lateral capillary plexus. Anat Rec Part A 272A:403–414, 2003. © 2003 Wiley‐Liss, Inc.
Multimode software defined radio receiver using direct conversion and low‐IF principle: Implementation and evaluation
Authors: Yoshida Hiroshi , Kato Takayuki , Tomizawa Takeshi , Otaka Syoji , Tsurumi Hiroshi
Published: April 2003

In recent years, software defined radio has attracted attention as radio with features that can be freely changed by software. The authors have previously proposed a concept for a receiver that converts the entire bandwidth of a desired system to digital signals and selects the signals of the desired channel in the digital stage. In addition, they have applied this concept to propose a basic configuration of a software defined radio using the direct conversion and low intermediate frequency (low‐IF) principle. In this paper, the authors investigated a specific implementation of the previously proposed wideband analog stage using the direct conversion and low‐IF principle and digital stage having an image rejection function and evaluated this implementation through experiments using the 1.5‐ and 1.9‐GHz bands. The results showed that a 10‐MHz wideband was implemented for the bandwidth and that at least 25 dB was obtained for the image rejection ratio by using the direct conversion principle and at least 61 dB was obtained by using the low‐IF principle. In addition, the authors performed the evaluation using the entire receiver and confirmed that the implementation was error free for multiple modulation modes. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(10): 55–65, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10004