bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and properties of 2‐vinylnaphthalene–EPDM–methyl methacrylate graft copolymer
Authors: Park Joo‐Yong , Park Duck‐Jei , Ha Chang‐Sik , Cho Won‐Jei 
Published: April 2003

AbstractA graft copolymer of 2‐vinylnaphthalene (2‐VN) and methyl methacrylate (MMA) onto ethylene–propylene–diene terpolymer (EPDM) was synthesized in tetrahydrofuran using benzoyl peroxide. The effects of EPDM content, and ratio of 2‐VN to MMA, reaction time, reaction temperature, and initiator concentration in the graft copolymerization were examined. The light resistance, thermal stability, and the tensile properties of the graft copolymer were investigated by using Fade‐o‐Meter, thermogravimetric analyzer, and tensile tester. It was found that the light resitance and the heat resistance as well as the tensile strength of the graft copolymer are considerably better than those of the acrylonitrile–butadiene–styrene (ABS) copolymer. © 1994 John Wiley & Sons, Inc.
The mechanisms of oxidative degradation of biomedical polymers by free radicals
Authors: Ali S. A. M. , Doherty P. J. , Williams D. F. 
Published: April 2003

AbstractDegradation is an essential factor in polymer biocompatibility. The physiological environment of the human body can be aggressive to polymers. Most implanted polymers suffer degradation and the kinetics and mechanisms of the processes can be significantly affected by various biologically active species, especially enzymes, lipids, peroxides, free radicals, and phagocytic cells. Iron enhances the toxicity of oxygen free radicals. Superoxide and hydrogen peroxide can interact to form the very toxic hydroxyl radical in the presence of iron. The data have shown that the hydroxyl radical is likely to be one of the main causes of polymer degradation in implantable devices. © 1994 John Wiley & Sons, Inc.
Fenton's reagent‐initiated graft copolymerization of acrylonitrile onto sodium alginate
Authors: Shah Samir B. , Patel Chandrakant P. , Trivedi Harikrishna C. 
Published: April 2003

AbstractGraft copolymerization of acrylonitrile (AN) onto sodium alginate was studied in an aqueous medium using ferrous ammonium sulfate–hydrogen peroxide (Fenton's reagent) as the redox initiator. To optimize the reaction conditions for affording maximum percentage of grafting, the concentrations of sulfuric acid, initiator components, monomer, and also temperature and time were varied. The results are discussed and a reaction mechanism is proposed. © 1994 John Wiley & Sons, Inc.
Rheological properties, tensile properties, and morphology of PP/EPDM/lonomer ternary blends
Authors: Kim Youngkyoo , Ha Chang‐Sik , Kang Tae‐Kyu , Kim Yang , Cho Won‐Jei 
Published: April 2003

AbstractThe rheological and tensile properties and the morphology of polypropylene (PP)/ethylenepropylene‐diene terpolymer(EPDM)/ionomer ternary blends were investigated, using a rheometric dynamic spectrometer (RDS), a dynamic mechanical thermal analyzer (DMTA), a tensile tester, and a scanning electron microscope (SEM). Two kinds of poly(ethylene‐co‐methacrylic acid) (EMA) ionomers, neutralized with different metal ions (Na+ and Zn++), were used. Blends were melt‐mixed, using a laboratory internal mixer at 190°C. The composition of PP and EPDM was fixed at 50/50 by wt % and the EMA ionomer contents were varied from 5 to 20 wt %, based on the total amount of PP and EPDM. It was found that the ternary blends, containing Na‐neutralized ionomer, showed considerably different rheological properties and morphology as compared to the PP/EPDM binary blends, due to the compatibilizing effect of the ionomer for PP and EPDM, while the ternary blends, containing the Zn‐neutralized ionomer, did not. The compatibilizing effect was most prominent at 5 wt % ionomer concentration. © 1994 John Wiley & Sons, Inc.
Studies on graft copolymerization of 2‐hydroxyethyl methacrylate onto poly(vinyl chloride)
Authors: Lee Wen‐Fu , Lai Cherng‐Ching 
Published: April 2003

AbstractPoly(vinyl chloride) was dehydrochlorinated in alkali solution and then grafted with 2‐hydroxyethyl methacrylate (HEMA) using benzoyl peroxide as a free‐radical initiator under a nitrogen atmosphere. The investigations involved examining the effects of grafting efficiency on various conditions, such as degree of dehydrochlorination, HEMA concentration, solvent effect, and reaction time. Maximum grafting to the extent of 57.2% was obtained. The mixed solvent grafting was attempted. © 1994 John Wiley & Sons, Inc.
The use of mica flakes for reducing internal stress in cured epoxy resin
Authors: Gupta V. B. , Brahatheeswaran C. 
Published: April 2003

AbstractMica, in the form of flakes of different sizes and size distributions, was mixed with a difunctional epoxy resin to the extent of 10 to 50 parts by weight of the resin. To this resin–filler mixture, a stoichiometric amount of a tetrafunctional curing agent was added. First, a thin a aluminium strip was coated with the mica–resin–amine mixture and was subjected to two curing cycles. Second, sheets were cast from the mixture by subjecting them to the same two cure cycles. The internal stresses that developed in the coated samples, and their relaxation with time, were studied. The dynamic torsional spectra of rectangular bars cut from the sheet were also mapped. The debonding and microcracking, resulting from internal stress, have been shown to result in a significant reduction in internal stress in the mica‐filled samples, particularly in samples containing large mica flakes in which delamination of the mica layers in the flake has also been shown to occur. However, despite this phenomenon, the filled samples were found to have adequate mechanical and electrical properties. © 1994 John Wiley & Sons, Inc.
Crystallization analysis fractionation: A new technique for the analysis of branching distribution in polyolefins
Authors: Monrabal Benjamin 
Published: April 2003

AbstractA new technique to analyze the short‐chain branching distribution (SCBD) in linear lowdensity polyethylene has been developed. The technique referred as crystallization analysis fractionation is based on a stepwise precipitation approach. By monitoring the polymer solution concentration during crystallization, the cumulative and differential SCBD can be obtained without the need of physical separation of fractions. The new technique has been shown to provide similar results to temperature rising elution fractionation but in a shorter time and with a simplified apparatus. It allows the simultaneous analysis of various samples and could also be used for analysis of polypropylene and other semicrystalline polymers that can be fractionated on the basis of crystallizability. © 1994 John Wiley & Sons, Inc.
Synthesis and characterization of liquid crystal photoresist
Authors: Yamashita K. , Kyo S. , Miyagawa T. , Nango M. , Tsuda K. 
Published: April 2003

AbstractA thermotropic liquid crystal polymer with photosensitive groups (liquid crystal photoresist), copoly(4‐methoxyphenyl) 4′‐(2″‐acroloyloxy ethoxy) benzoate (MPAEB)‐4‐vinylbenzyl cinnamate (VBC) was prepared, and its thermal behavior was characterized by a differential scanning calorimetry. The copolymer exhibited a liquid crystal mesophase between approximately 70°C and 120°C. In the mesophase, poly(MPAEB‐VBC) (85/15) had a higher photo‐crosslinking ability than that at room temperature and at 140°C, where the copolymer exhibited the isotropic phase. It was found that the liquid crystal photoresist had a high crosslinking ability owing to alignment of its photosensitive groups. © 1994 John Wiley & Sons, Inc.
Dyeability of silk fabrics modified with dibasic acid anhydrides
Authors: Freddi Giuliano , Tsukada Masuhiro , Kato Hiroshi , Shiozaki Hideki 
Published: April 2003

AbstractSilk fabrics were chemically modified with different kinds of dibasic acid anhydrides. Samples with different acyl contents, ranging from 24 to 107 mol/105g, were obtained by reaction with succinic (S), glutaric (G), phthalic (PA), and 0‐sulfobenzoic (OSBA) anhydrides. Dyeability with a cationic dye (Rhodamine B, C.I. Basic Violet 10) was determined by measuring dye uptake and K/S values. Following acylation, the absorption of basic dye was significantly enhanced for all samples. The maximum dye uptake was attained by OSBA‐treated silk fabrics, while samples treated with S. G. and PA did not differ significantly. Dye uptake increased regardless of the content, at least in the range examined. Reflectance measurements and K/S values confirmed the trend evidenced by dye uptake results. © 1994 John Wiley & Sons, Inc.
Effect of environmental factors on the mechanical properties of grafted casein films: Influence of temperature and extension rate
Authors: Somanathan N. 
Published: April 2003

AbstractCasein was grafted with acrylonitrile (AN) and with a binary mixture of acrylonitrile and n‐butyl methacrylate (n‐BMA). Stress‐strain characteristics of these films were analyzed as a function of temperature and rate of extension. The results shows that both the systems are sensitive to temperature. Due to the incorporation of n‐BMA, the material becomes flexible since the Tg of the multiphasic polymer was reduced and therefore shows the changes even at lower temperatures when compared to casein grafted with AN. The fracture morphologies of the binary mixture‐grafted casein films show that the effect produced by temperature and rate of extension are inversely related. © 1994 John Wiley & Sons, Inc.
Effect of surfactants on the particle sizes of red#170 polyurea microcapsules
Authors: Kuo Y. M. , Wu C. T. , Wu W. H. , Chao D. Y. 
Published: April 2003

AbstractRed#170 (pigment) polyurea microcapsules have been successfully prepared at our laboratory. Both core and shell of these microcapsules are demonstrated to be red#170 pigment and polyurea, respectively, by infrared (IR) spectra. The number‐average particle sizes of these microcapsules are seen to decrease with increasing concentration and the ethylene oxide chain length of nonylphenylpolyoxyethylene ether (NPn; n = 6, 8, 10, 12, 16) as an emulsifier in the water phase used for making microcapsules. Experimental results indicate that the average particle sizes of red#170 polyurea microcapsules are smaller for the system with NP16 than for the system with NP4 (in the oil phase) and/or NP16 (in the water phase) and that, in the presence of NPn, these particle sizes are seen to be slightly smaller for use of methylcellulose than for use of sodium carboxymethylcellulose as a protective colloid. It is also interesting to note that the released amounts of red#170 pigment from polyurea microcapsules in di‐n‐butylphthalate solvent is lower for a system with NP16 than for a system with methylcellulose, as a result of good emulsification leading to decrease the interaction between toluene diisocyanate and water molecules. This may further cause more crosslinkage to take place at the urea groups, resulting in a decrease in the porosity of the capsules. © 1994 John Wiley & Sons, Inc.
Properties of oriented polyethylene bars of large cross section
Authors: Courval Gregory , Wang Li‐Hui , Porter Roger S. 
Published: April 2003

AbstractThe solid‐state extrusion technique has been used to prepare uniaxially oriented polyethylene bars with rectangular end cross sections of 6 × 50 mm2. They were extruded at 110°C from billets of high density polyethylene. The tensile modulus and strength for the extrudate with a draw ratio (DR) of 14 were 17.9 and 0.32 GPa, respectively. The mechanicals were also measured in the transverse direction by means of the proportional elastic limit (PEL) bending test. The PEL results do not change after DR 14 due to the fibrillate structure formation. Crystallinity and shrinkage tests were made on samples taken over the bar cross section. They show that uniform properties were achieved across the width of the bar with proper die design. © 1994 John Wiley & Sons, Inc.
Continuous polymerization of caprolactam in a modular intermeshing corotating twin screw extruder integrated with continuous melt spinning of polyamide 6 fiber: Influence of screw design and process conditions
Authors: Kye Hyoungsan , White James L. 
Published: April 2003

AbstractThe continuous anionic polymerization of caprolactam to polyamide‐6 in a modular, intermeshing, corotating twin screw extruder was investigated. Caprolactam was polymerized by anionic polymerization techniques under a range of processing conditions, including different screw configurations, temperature profiles, screw speeds, and throughputs. Studies were also made of melt spinning polyamide 6 into oriented filaments. The polyamide‐6 melt spun filaments were characterized using birefringence and wide angle X‐ray diffraction. Uniaxial stress measurements of the fibers were obtained and are reported. The results for the melt spun filaments compare favorably with the previous literature. © 1994 John Wiley & Sons, Inc.
Immobilization of spent ion‐exchange resins in the urea‐formaldehyde matrix
Authors: Rao S. V. S , Kothandaraman H. , Sudhakar M. , Lal K. B. , Amalraj R. V. 
Published: April 2003

AbstractStudies have been carried out on the immobilization of spent ion‐exchange resins produced in nuclear power plants in urea‐formaldehyde matrix. The matrices were prepared by incorporating different types of ion‐exchange resins in the pH range of 4.5 to 5.0, using boric acid as a catalyst. Characterization of the matrices was carried out with respect to dimensional changes, compressive strength, and leach resistance. The cumulative percentage weight loss and volume change were observed to decrease with the increase in boric acid concentration before attaining a plateau. The diffusion coefficients were in the order of 10−16 M/s, and the compressive strengths were in the range of 0.83 to 12 MPa. Infrared spectral studies on the urea‐formaldehyde matrices revealed that the rate and the extent of cure depended on the type of resin. © 1994 John Wiley & Sons, Inc.
Flocculation behavior of some cationic polyelectrolytes
Authors: Smith‐Palmer Truis , Campbell Nicole , Bowman Janice L. , Dewar Patricia 
Published: April 2003

AbstractThe settling rates and adsorption isotherms produced by a variety of suites of cationic polyelectrolytes in 3% kaolin suspensions were measured. Settling rates increased with molar mass even for low‐mass, high‐charge polymers. The very high settling rates produced by cationic copolymers of acrylamide decreased as the charge density of the polymer used increased. Hydrolysis of unbuffered polymers occurred over time and produced large changes in the effectiveness of the polymers. This is attributed to conformational changes. © 1994 John Wiley & Sons, Inc.
Investigation of the miscibility of polycarbonate–poly(ethyleneterephthalate) blends: Solid‐state 1H‐NMR T1 relaxation time measurements, transmission electron microscopy, and structure–properties relationship
Authors: Abis L. , Braglia R. , Camurati I. , Merlo E. , Natarajan K. M. , Elwood D. , Mylonakis S. G. 
Published: April 2003

AbstractSolid‐State 1H‐NMR measurements of T1 relaxation times performed on polycarbonate‐poly(ethyleneterephthalate) (PC–PET) blends point out the presence of two separate domains with apparent dimensions of about 80 nm. The variation of PET domain relaxation time with the increase of PC content is explained in terms of an interface in which parts of the PC molecules are finely dispersed into the PET matrix. Relaxation parameters and compositions match very well an equation that quantitatively describes a three‐phase model formed by two domains separated by an interface of mixed components. Micrographs obtained by transmission electron microscopy (TEM) clearly reveal the presence of two separate domains with a phase inversion at 40/60 wt% composition. PET domains, although larger than expected from NMR analysis, are characterized by a dispersion of small PC particles that are considered responsible for the observed diffusion of magnetization from PET to PC domains. The partial miscibility seems to be physical in nature rather than due to transesterification processes between the components, as stem from 1H‐NMR spectra in solution of PET and PC–PET blends. T1 relaxation times measured in the same way on totally immiscible PC–PA‐6 blends, support, by contrast, the NMR interpretation of PC–PET results. The mechanical properties of PC–PET blends exhibit ductile behavior throughout the entire range of composition. This indicates that PC and PET are mechanically compatible. This is also in agreement with the isothermal crystallization data for PET at various compositions of PC–PET. These results are in agreement with the existence of a partial miscibility between PET and PC. © 1994 John Wiley & Sons, Inc.
Influence of N‐acetylglycine on the kinetics of the ceric ion‐initiated graft copolymerization of acrylonitrile and methyl methacrylate onto jute fibers
Authors: Patra C. M. , Singh B. C. 
Published: April 2003

AbstractThe influence of N‐acetylglycine on the kinetics of graft copolymerization of acrylonitrile (AN) and methyl methacrylate (MMA) onto chemically modified jute fibers was studied in the temperature range 40–60°C. The optimum conditions for grafting have been determined by studying the effects of concentrations of monomers, Ce(IV), and N‐acetylglycine on the rate of grafting. Besides the effect of time, temperature, and concentration of the acid, the amount of jute fibers and some organic solvents and inorganic salts on the rate of grafting has been investigated. On the basis of experimental findings, a kinetic scheme has been proposed. Infrared spectra of chemically modified jute and grafted jute have been investigated. More than 185% graft yield could be achieved with the present system. Grafting has improved the thermal stability of jute fibers. © 1994 John Wiley & Sons, Inc.
Effect of chemical and physical crosslinks on strength of rubber and plastics—a theoretical approach
Authors: Furukawa Junji , Yamada Eisuke 
Published: April 2003

AbstractFor rupture of rubber and plastics, three types are proposed: (a) elastic, (b) plastic, and (c) brittle. For (a) the rupture takes place at the ultimate elongation of chains between crosslinks. Strength f is proportional to the number of crosslinks and also the fraction of effective chains giving the optimum degree of vulcanization ν. Both ν and f at the maximum strength decrease with increasing the bond energy D of crosslinks. The rupture in (b) occurs for filled rubbers. The maximum reinforcement with filler is expected to be attained at 20% volume fraction of filler from the pseudo‐link model in which the number of links are proportional to the specific surface area, the fraction, and the adsorption ability of the filler particles. For (c) the craze occurs due to the breakdown of pseudo‐crosslinks of the smallest size b, and b is 2 at the glass transition temperature. Impact strength is improved by the dispersion of rubber particles at the optimum fraction of 13% and under the small distance of neighboring particles, which is 0.4 μm and is corresponding to the relaxation distance. © 1994 Wiley & Sons, Inc.
Molecular weight measurement in weathered polymers
Authors: O'Donnell B. , White J. R. , Holding S. R. 
Published: April 2003

AbstractGel permeation chromatography has been used to monitor the molecular weight changes that occur when polymers are degraded by photooxidation. Methods of sample preparation and procedures for conducting the chromatography measurements and for analyzing the results are discussed. Examples are given of applications to studies of polystyrene (PS), polypropylene (PP), and glass fiber‐reinforced polypropylene (GFPP) exposed to ultraviolet (UV) irradiation in the laboratory. The results show that the degradation rate is fastest near the exposed surface, but in PS and PP, degradation is much faster at the unexposed surface than in the center of the molding, where the UV intensity is greater than at the unexposed surface. It is deduced that degradation at the center is slowed by a shortage of oxygen. © 1994 John Wiley & Sons, Inc.
Automated microscopic technique for evaluating poly(vinyl chloride)–plasticizer compatibility
Authors: Caldas V. , Radiotis T. , Brown G. R. 
Published: April 2003

AbstractAn automated microtechnique has been developed that permits a rapid, reproducible determination of the Flory–Huggins χ interaction parameters for poly(vinyl choloride)–plasticizer systems. It is a modification of the Anagnostopoulos method of determining an apparent melting temperature of a poly(vinyl chloride) (PVC) particle in excess plasticizer. A microscope equipped with a photodiode sensor is used to measure changes in the light transmitted through a plasticizer sample containing a PVC particle as the temperature is increased at a fixed rate, either 0.2 or 1.0°C/min. Data acquisition is done by computer so that minimal operator assistance is required. The apparent melting region is characterized by a sigmoidal change in the light transmitted through a fixed sample area. This curve allows an accurate, reproducible definition of the apparent melting temperature from which the χ parameter is easily derived. The values obtained for the interaction parameter of PVC with four plasticizers chosen from the phthalate and phosphate families are in good agreement with general trends of solvent quality. Separate experiments demonstrated that the overall transmittance profile reflects changes in both the size and the optical clarity of the PVC particle during heating. This leads to added features in the profile that reflect important diffusion and swelling characteristics for a given system. © 1994 John Wiley & Sons, Inc.
Synthesis and structural investigation of conductive composites from cellophane and polypyrrole
Authors: Bhat N. V. , Shaikh Y. B. 
Published: April 2003

AbstractA versatile method for preparing conducting composites from cellophane and pyrrole by an interface technique has been attempted. Polymerization of pyrrole into the porous matrix of cellophane produces black, flexible composite film with conductivity comparable to that of polypyrrole and mechanical properties very similar to cellophane. © 1994 John Wiley & Sons, Inc.
Correlations between rheological and mechanical properties of mineral filled polypropylene compounds
Authors: Gahleitner M. , Bernreitner K. , Neißl W. 
Published: April 2003

AbstractA comparative study of rheological and mechanical properties of Polypropylene compounds with talc as a mineral filler is presented. It turns out that the main factors determining the mechanical behavior, namely (a) filler concentration, (b) filler particle size, and (c) degree of dispersion, influence the linear viscoelastic properties as well. Thus, a quick method for estimating compound properties from melt rheology is established. © 1994 John Wiley & Sons, Inc.
Partially miscible blends of epoxy resin and epoxidized rubber: Structural characterization of the epoxidized rubber and mechanical properties of the blends
Authors: Bussi Philippe , Ishida Hatsuo 
Published: April 2003

AbstractThe cure process and the mechanical properties of blends of diglycidyl ether of bisphenol‐A–based epoxy resin and hydroxyl terminated, internally epoxidized polybutadiene rubber have been studied. Internal oxirane groups are characterized by a main absorption at 885 cm−1 in the infrared spectrum while the terminal oxirane groups of the diepoxide monomer absorb at 913 cm−1. In the absence of prereaction of the rubber, gelation of the epoxy matrix occurs much faster than any reaction involving the internal oxirane groups or the terminal hydroxyl groups. Therefore, only weak chemical bonding between the rubber particles and the epoxy matrix exists and the fracture toughness of the blends does not show any significant improvement. Upon prereaction of the rubber with an excess diepoxide monomers, a 40% improvement in the value of the critical stress intensity factor is obtained. However, dynamic mechanical spectra of these blends acquired in the rubbery plateau region uniquely demonstrate that this improvement is due to the incorporation of the rubber into the epoxy network rather than to the presence of phase‐separated rubber particles. © 1994 John Wiley & Sons, Inc.