bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flexibility improvement of epoxy resin by using polysiloxane–PGMA (MMA) composite particles
Authors: Tong Jiangdong , Bai Ruke , Pan Caiyuan , Goethals Eric J. 
Published: April 2003

AbstractA study on the increase of the flexibility and decrease of the internal stress of cured epoxy resins by addition of polysiloxane rubber particles grafted with and without glycidyl methacrylate (GMA) or methyl methacrylate (MMA) is reported. Polysiloxane latex was obtained by cycling a mixture of polysiloxane containing a vinyl group and aSiH group, respectively, emulsifier, and water in a homogenizer. Graft polymerization of GMA (or MMA) on these rubber particles was performed in the latex under γ‐ray irradiation of 60Co. The rubber particles were used to improve the flexibility of the epoxy resin. The particles grafted with GMA showed a homogeneous distribution in the matrix, better inducing and terminating craze. Comparisons were made among the particles grafted with MMA and various MMAGMA or a series of GMA; the results indicated that the particles grafted with GMA (graft ratio = 10%) showed the greatest increase of elongation and decrease of internal stress. The factors influencing the toughness of the epoxy resin matrix are discussed. © 1995 John Wiley & Sons, Inc.
Survey of preparation techniques of monodispersed microspheres of glycidyl methacrylate and its derivatives
Authors: Hoshino Mitsutoshi , Arishima Koichi 
Published: April 2003

AbstractThis article describes the preparation of monodispersed microspheres of glycidyl methacrylate, 2‐hydroxyethyl methacrylate, and triethylene glycol dimethacrylate by radical polymerization. The initial stage of the polymerization reaction began in the liquid phase. As the polymerization proceeded, a nuclear polymer chain of microspheres was generated from soluble oligomeric radicals and then solidified from the liquid phase. The radius of the microspheres was controlled by polymerization parameters, such as monomer concentration, polymerization time, and the kind of polymerization solvent. A small number of thin platelike substances may be produced by the anisotropy of the two‐dimensional monomer added to the oligomeric radicals. The monodispersed microspheres were achieved through the use of the following: (1) a fluorinated tube in which the polymerization reaction proceeded; (2) a monomer concentration of about 1 mol/L; (3) a higher concentration of crosslinking regeant than used commercially; (4) the prevention of the occurrence of polymer microsphere aggregation; (5) pouring the solution mixtures into a large amount of cooled acetone after the polymerization reaction; and (6) the use of a low‐temperature purification process and centrifugation at low temperature. This article describes the mechanism of microsphere formation and growth by solution polymerization. © 1995 John Wiley & Sons, Inc.
Introduction of functional groups on polyethylene surfaces by a carbon dioxide plasma treatment
Authors: Terlingen Johannes G. A. , Gerritsen Hermina F. C. , Hoffman Allan S. , Feijen Jan 
Published: April 2003

AbstractPoly(ethylene) (PE) films were treated with a carbon dioxide (CO2) plasma to study the formation of oxygen‐containing functional groups at the surface. Modified and nonmodified films were characterized by X‐ray photoelectron spectroscopy (XPS) and water contact angle measurements. During the CO2 plasma treatment, the PE surface is etched and oxidized, yielding films with a very hydrophilic surface. The oxygen incorporation at the surface is fast and can be described by a combination of a zero‐order incoraporation and a first‐order etching process. Several oxygen functionalities such as carboxylic acid (approximately 14% of the oxygen persent), ketone/aldehyde (25%), and hydroxyl/epoxide (5–9%) groups were introduced at the surface by the plasma treatment. This was shown by using derivatization reactions for specific functional groups followed by XPS analysis. The wettability of the plasma‐treated surface decreased when the films were stroed for prolonged periods of time in air. This aging process could not be completely reversed by immersion of the films in water. © 1995 John Wiley & Sons, Inc.
Synthesis of graft copolymers. Part I. Synthesis of macroinitiators
Authors: Morales Graciela , Castro Efraín , Kaluyzhnaya Elena , Guerrero‐Santos Ramiro 
Published: April 2003

AbstractThermal polymeric initiators, having pendant 1,2‐bis(trimethylsilyloxy)tetraphenylethane (or benzopinacolate) groups along the chain, have been prepared. First, the reactivity ratios of 4‐vinylbenzophenone (4VBP) and 4‐methacryloyloxybenzophenone (MOB) copolymers with styrene or methylmethacrylate were determined. Then the randomly containing 4VBP or MOB copolymers were transformed into polymeric initiators by duplication reaction of the attached benzophenone. Polymerization of MMA or St initiated by the resulting copolymers having pendant benzopinacolate groups was carried out yielding PMMA‐g‐PS and PS‐g‐PMMA. © 1995 John Wiley & Sons, Inc.
A simple neural network based model approach for nylon 66 fabrics used in safety restraint systems: A comparison of two training algorithms
Authors: Keshavaraj Ramesh , Tock Richard W. , Nusholtz Guy S. 
Published: April 2003

AbstractAirbag technology relies on woven fabrics as the material of construction and particularly on knowledge pertaining to the fabric's permeability as a function of pressure drop, inflation temperature of the gas, fabric weave, fiber denier, and biaxial stress–strain relationships under biaxial conditions. While fabric permeability can be quantified by actual experimental measurements, the number and nonlinearity of the variables involved make the experiments time‐ and cost‐intensive. Moreover, interpolations within a given data set can yield questionable results. In this study, a very simple feed forward neural network architecture was used with a training rule involving a nonlinear optimization routine for updating weights of the proposed network. This training was compared to the training with an error‐back propagation routine. During this training, the ANN is introduced to data that contain the actual cause and effect patterns, with adjustments being made by changes in weighting factors until the errors in the output variables are minimized. Once trained, ANN can ascertain the essentials of the relationships and assimilate henceforth. In this study, after the initial training, the ANN was tested on additional data which were not part of the training processes. The predictions of the proposed trained network agreed very well with the new experimental data. On this basis, the proposed ANN model appears to be an effective tool for modeling airbag fabric behavior. This ANN model can assimilate relationships between different variables from the real‐world data and does not require extensive normalizing of the process data like a back‐propagation algorithm. Once trained, only fractions of a second are needed for information assimilation and output generation. This coupled with simplicity of use and accuracy of predictions from the real‐world data make this ANN model attractive for on‐line applications. © 1995 John Wiley & Sons, Inc.
Mechanism of radiation vulcanization of natural rubber latex sensitized by monoacrylates
Authors: Hill D. J. T. , O'Donnell J. H. , Perera M. C. S. , Pomery P. J. , Smetsers P. 
Published: April 2003

AbstractThe mechanism of radiation vulcanization of natural rubber with 2‐ethyl hexyl acrylate (2EHA) monomer was investigated using electron spin resonance spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The primary radicals formed in the arcylate molecule were found to abstract the allylic hydrogens of the polyisoprene. Crossliking may occur through the allylic radicals and/or main chain radicals formed on the polyacrylate. Acrylate was found to concentrate in the rigid regions of the crosslinked rubber indicating heterogeneity and a nonuniform distribution of the acrylate in the latex particles. The addition of the acrylate and the irradiation seems to effect the Brownian motion of the latex particles. Both the viscosity and the NMR peak widths are effected by the irradiation. Addition of 5% 2EHA increases the crosslinking by a factor of 3.6. The thermal stability of the rubber first increases with the dose in the presence of acrylate, but drops at higher doses due to peroxide formation. © 1995 John Wiley & Sons, Inc.
Synthesis, characterization, and thermotropic properties of side‐chain liquid crystalline polysiloxane polymers with an oligo(ethylene oxide) unit in the side chain
Authors: Chang‐Chien Guo‐Ping , Kuo Jen‐Feng 
Published: April 2003

AbstractA series of new alkene and octenyloxy monomers containing 4′‐[oligo(ethylene oxide)] n monomethyl ether 4‐biphenyl ether carboxyl benzoate [MS3BDBEn] (n = to 3) and 1‐ (p‐methoxydiphenyl)–(carboxyl benzoate) [oligo(ethylene oxide)]n [MSm+2BEnDB] (m = 1, 6; n = 1 to 3) as end groups were synthesized. The molecular structure of the monomers was charaterized using nuclear magnetic resonance (NMR) spectroscopy. These monomers were grafted onto poly(methylhydrosiloxane)s (PMHS) by the platinun‐catalyzed hydrosilylation process. The thermal transition temeratures and mesophase textures of the monomers and the polysiloxane polymers have been determined by diffential scanning calorimetry (DSC) and by polarized optical microscopy. The effect of changes in chemical structure on the mesophase properties, glass transition temperature, isotropic temperature, and mesophase texture of the monomers and the polysiloxane polymers is discussed. Polymers PS3BDBEn showed smectic and nematic phases which were not analogous to their precursor nematic monomers MS3BDBEn. Both monomers MSm+2BEnDB and their polymeric homologous PSm+2BEnDB did not exhibit mesophase properties. This demonstrated that the polymer effect could not stabilize the mesophase obtained from mesogenic core which contained a flexible oligo(ethylene oxide) unit interconnecting aromatic group. © 1995 John Wiley & Sons, Inc.
Surface modification of calcium carbonate used for polypropylene blending with dimeric aluminates
Authors: Liao Kairong , Chen Xuexin , Zheng Chenmou 
Published: April 2003

AbstractThere kinds of dimeric aluminates (2DH‐306, 2DH‐324, and 2DH‐335) have been used for surface modification of calcium carbonate (CaCO3) particles. The dimeric aluminates were shown to have an appreciable coupling effect at the interfaces between the light calcium carbonate (L‐CaCO3) and polypropylene (PP) in the blends by mechanical property study and SEM observation. In the 2DH‐306 modified L‐CaCO3/PP (25/75) system, the impact strength exceeded that of the nonmodified system by more than 30 kJ/m2. X‐ray study showed that the dimeric aluminates had a synergistic effect with L‐CaCO3 on the formation of PP β‐crystal, which would exert an important influence on the elongation ratio at break for the L‐CaCO3/PP blends. © 1995 John Wiley & Sons, Inc.
Permeation of simple gases through plasma polymerized films from fluorine‐containing monomers
Authors: Oh Saejoong , Zeng Yuan , Koo Ja‐Kyung , Zurawsky W. P. 
Published: April 2003

AbstractThe permeation of several different permanent gases through plasma polymer membranes was studied. The plasma polymers were produced by a microwave discharge of various fluorine‐containing monomers. Plasma polymers made from fluorine‐rich monomers (F/C ≈ 1) yield films with the highest selectivities; those made from low fluorine content monomers show very little selectivity among the various gases. CO2 solubility is very high in the fluorine‐rich plasma polymers and gives rise to large CO2 to CH2 selectivities. © 1995 John Wiley & Sons, Inc.
Rubberwood–polymer composites based on diallyl phthalate and methyl methacrylate
Authors: Rozman H. D. , Kumar R. N. , Abusamah A. 
Published: April 2003

AbstractWood–polymer composites (WPC) of rubberwood (Hevea brasiliensis), were prepared by impregnating the wood with methyl methacrylate (MMA), and the combinations of MMA and diallyl phthalate (MMA/DAP). Polymerization was carried out by catalyst heat treatment. Impregnated samples showed significant improvements in compressive and impact strengths, hardness, and dimensional stability (toward water) over that the untreated rubberwood. © 1995 John Wiley & Sons, Inc.
Tetramethylthiuram disulfide and 2‐mercaptobenzothiazole as binary accelerators in sulfur vulcanization. I. Exchange reactions between the accelerators and sulfur in the absence of rubber
Authors: Giuliani B. V. M. K. , McGill W. J. 
Published: April 2003

AbstractExchange reactions between tetramethylthiuram disulfide, 2‐mercaptobenzothizole, and sulfur were studied by heating powdered mixes to vulcanization temperatures at a programmed rate in a DSC. The reaction was stopped at points along the thermal curve and the mixture was analyzed by HPLC. On dissolution, even unheated samples undergo a sulfide exchange reaction leading to a mixed accelerator, while polysulfides of the thiuram and mixed accelerator form in low concentrations. On heating, higher concentrations of these polysulfides are formed, particularly in the presence of elemental sulfur. Dimethyldithiocarbamic acid, formed in the exchange, influences the product spectrum if it remains trapped in the DSC pan. Tetramethylthiourea is formed only at elevated temperatures when dimethylamine, a degradation product of the acid, is trapped in the DSC pan. A series of reactions is proposed to explain the product spectrum obtained under different conditions. © 1995 John Wiley & Sons, Inc.
Carbon–polymer composite electrodes for redox cells
Authors: Haddadi‐Asl V. , Kazacos M. , Skyllas‐Kazacos M. 
Published: April 2003

AbstractConductive carbon–polymer composite electrodes for the vanadium redox flow battery were developed and their properties investigated. Conductive polymer composite materials were fabricated by mixing PVC, nylon 6, nylon 11, LDPE, and HDPE with conductive fillers. To overcome the deterioration in the mechanical properties of carbon–polymer composites with high carbon loading, a range of chemically resistant rubbers was blended into the composites. Electrical, mechanical, permeation, and electrochemical studies show that the HDPE composite is the best electrode matrix material for the vanadium redox battery. The performance of a vanadium redox flow cell employing the best composite electrode was also evaluated and voltage efficiencies as high as 88% were obtained with electrodes employing graphite felt active layers bonded to the carbon–polymer composite substrates. © 1995 John Wiley & Sons, Inc.
Synthesis of formaldehyde‐dibenzo‐18‐crown‐6 condensation resins containing phosphonic acid groups and their alkali‐metal cation sorption
Authors: Zhao Qiang , Bartsch Richard A. 
Published: April 2003

AbstractIon‐exchange resins are prepared by introducing phosphonic acid monoethyl ester or phosphonic acid groups into formaldehyde condensation poly(dibenzo‐18‐crown‐6) resin. The phosphonic acid ion‐exchange groups provide accessibility for metal cations, while the ion‐selective cyclic polyether binding site influences the selectivity. The selectivities and efficiencies for competitive alkali‐metal cation sorption from aqueous solutions by these crown ether‐containing phosphonic acid resins are strongly influenced by the pH of the aqueous solution, the identity of the phosphonic acid groups, and the molar ratio of ion‐exchange groups to crown ether units. © 1995 John Wiley & Sons, Inc.
Study of radical copolymerization of tetrafluoroethylene with ethylene in suspension
Authors: Kostov G. K. , Nikolov Al. T. 
Published: April 2003

AbstractRadical copolymerization of tetrafluoroethylene (TFE) with ethylene (E) was initiated by 2,2′‐azo‐bis‐isobutyronitrile in batch and semibatch operation. The effect of reaction conditions (temperature, pressure, stirring speed, molar ratio of monomers, etc.) on copolymerization rate and copolymer molecular weight was studied. The highest reaction rate was observed at TFE content over 70 mol % and was found to be proportional to initiator concentration and total monomer content by powers of 0.9 and 1.54, respectively. These dependencies were attributed to the heterophase character of the copolymerization.The monomer reactivity ratios and overall activation energy of the reaction were determined. The effect of the monomer composition on the distribution of monomer units in the copolymer chain was studied. Kinetic mechanism of the copolymerization was suggested.Some of the basic physical properties and chemical resistance of the alternating copolymers synthesized were also determined. © 1995 John Wiley & Sons, Inc.
The effects of spinning conditions on the structure formation and the dimension of the hollow‐fiber membranes and their relationship with the permeability in dry–wet spinning technology
Authors: Kim Jeong‐Hoon , Park You‐In , Jegal Jonggeon , Lee Kew‐Ho 
Published: April 2003

AbstractHollow‐fiber membranes were prepared by dry–wet spinning under different spinning conditions. The used spinneret was tube‐in‐orfice type and the membrane material was polysulfone (Udel P‐3500). N‐methyl‐2‐pyrrolidinone (NMP) and water were used as solvent and coagulant, respectively. The concentration of the dope solution was 22 wt %. The effects of the three spinning factors—spinning height; extrusion rates of dope solution and inner coagulant; dimensions (inner diameter, outer diameter, and thickness) and permeation properties of the hollow‐fiber membranes—were studied. The results were as follows: With changes in the spinning factors, spinning velocity and falling time before the membrane entered the water (coagulant) were changed; consequently, the structures and the dimensions of the hollow‐fiber membranes varied with a certain tendency. The permeation properties of the hollow fibers were related very closely to the changes in the fibers' structures and dimensions. © 1995 John Wiley & Sons, Inc.
Influence of activation time on the properties of polyacrylonitrile‐based activated carbon hollow fiber
Authors: Yang Ming‐Chien , Yu Da‐Guang 
Published: April 2003

AbstractActivated carbon hollow fiber (ACHF) was prepared from polyacrylonitrile (PAN) hollow fiber through carbonization in nitrogen and activation with carbon dioxide. The effect of the activation time on the pore size distribution and the surface structure of the resulted ACHF was investigated. The results show that increasing the activation time at 800°C can increase the number of pores and reduce the crystal size, the tensile strength, the modulus, and the elongation. © 1995 John Wiley & Sons, Inc.
A simple and efficient SEC/GPC linear calibration technique using broad‐range standards
Authors: Nwankwo Emeka O. , Abbott Scot D. 
Published: April 2003

AbstractA simple method for calibrating high‐performance SEC/GPC systems is presented. This technique sequentially finds the correct slope, D2, by tracking the calculated polydisperity, P, using arbitrary calibration slopes from which the intercept, D1, is ultimately back‐calculated. The case of application and relative efficiency of this search technique are highlighted and discussed. Theoretical justification of the simple form of the convergence equation is presented using two distribution models—the Gaussian (pseudo‐Flory) and the sine (cosine) exponential models. © 1995 John Wiley & Sons, Inc.
Modification of PP/HDPE blends by PP‐PE sequential polymerization product
Authors: Zhu Wei , Zhang Xuequan , Huang Baotong , Feng Zhiliu 
Published: April 2003

AbstractThe morphology and mechanical properties of polypropylene/high‐density polyethylene (PP/HDPE) blends in a wide range of compositions modified by a sequential Ziegler‐Natta polymerization product (PP‐PE) have been investigated. PP‐PE contains multiple components such as PP, ethylene‐propylene copolymer (EPC), and high molecular weight polyethylene (HMWPE). The effects of PP‐PE on the mechanical properties and morphology of the PP/HDPE blends are the aggregative results of all its individual components. Addition of PP‐PE to the blends not only improved the tensile strength of the blends, but the elongation at break increased linearly while the moduli were nearly unchanged. Morphological studies show that the adhesion between the two phases in all the blends of different compositions is enhanced and the dispersed domain sizes of the blends are reduced monotonously with the increment of the content of PP‐PE. PP‐PE has been demonstrated to be a more effective compatibilizer than EPC. Based on these results, it can be concluded that the tensile strength of the blends most on the adhesion between the two phases and the elongation at break depends most on the domain size of the dispersed component. © 1995 John Wiley & Sons, Inc.
Evaluation of recycled PP/rubber/talc hybrids
Authors: Long Yu , Tiganis Bill E. , Shanks Robert A. 
Published: April 2003

AbstractMechanical properties of recycled PP/rubber/filler systems were studied and mechanisms were discussed on the basis of molar mass and molar mass distribution, morphologies, and thermal behavior. Characteristics of recycled PP/rubber/filler depend on degradation of PP and additional components. Recycling processes decreased impact strength, but it seemed not to affect tensile properties significantly. Aging with UV and moisture affected mechanical properties by some degree of PP chain scissions and ethylene chain crosslinking in EP rubber. Inorganic filler acted as a crack center and accelerated aging degradation. Paint decreased mechanical properties significantly by introducing stress concentrations. Recycle processing decreased the molar mass and increased the molar mass distribution of PP. Aging with UV decreased crystallization temperature and increased crystallization half‐time by decreasing nucleation. © 1995 John Wiley & Sons, Inc.
Poly(styrene‐graft‐ethylene oxide) as a compatibilizer in polystyrene/polyamide blends
Authors: Jannasch Patric , Wesslén Bengt 
Published: April 2003

AbstractPolystyrene (PS) blends containing a dispersed phase of either polyamide‐6 (PA‐6) or polyamide‐12 (PA‐12) were compatibilized by additions of 1, 3, or 5 wt % poly(styrene‐graft‐ethylene oxide). The graft copolymers were found to have a stabilizing effect on the domain sizes. Weight average radii of PA‐6 domains in compression molded samples were reduced by a factor of 5 with 3 wt % graft copolymer added. The corresponding size reduction for PA‐12 domains was by a factor of 3. Also, the domain sizes were more uniformly distributed in blends containing the graft copolymers. Thermal analysis of the blends revealed that compatibilization retarded the PA crystallization, with some PA crystallizing at the PS glass transition. This retarded crystallization is explained as a result of the domain size reduction and by the presence of graft copolymer at the interface. The graft copolymers had a toughening effect on the blends and the impact strength of a PS/PA‐12 blend was improved by 65% by adding 3 wt % of graft copolymer. Binary blends of the PA and poly(ethylene oxide) (PEO) were investigated in a separate study to verify miscibility of the graft copolymer side chains and the PA. Hydrogen bonding between PA‐6 and PEO was confirmed by IR spectroscopy and partial miscibility was indicated by melting point depressions. © 1995 John Wiley & Sons, Inc.