bluuebunny/crossref_metadata_2025_split huggingface dataset:
Instrumented impact testing of a glass swirl mat‐reinforced reaction injection‐molded polyamide block copolymer (NBC)
Authors: Karger‐Kocsis J. 
Published: April 2003

AbstractThe fracture behavior of a reaction injection‐molded (RIM) polyamide block copolymer (NBC) reinforced with a continuous glass strand mat (swirl mat) was studied in instrumented high‐speed impact‐bending tests. Investigations were carried out on Charpy and Izod specimens of different size and notching direction to elucidate specimens' size effects. From the tests performed at ambient temperature and −40°C, fracture mechanical parameters (fracture toughness, fracture energy) andE‐modulus were derived. Changes observed in the above parameters of the matrix were attributed to a molding‐induced skin‐core morphology. Both fracture toughness and energy of the composites depended strongly on the type, i.e., on the ligament width (W) and length‐to‐span ratio (L0/L) of the specimens. Reliable fracture mechanics data can be determined in three‐point bending whenW> 12 mm andL0/L> 1.7 for the specimens. The fracture toughness andE‐modulus increased monotonously, whereas the fracture energy reached a plateau as a function of fiber mat content. Their values were only slightly influenced by the temperature. It was also shown how molding‐and machining‐induced flaw size can be defined. The failure mode of the materials was studied by fractography and the failure events were summarized in a model and discussed.
Preparation of cationic water‐absorbent resin from PEI and PEO
Authors: Qirong Liu 
Published: April 2003

AbstractHydrophilic network copolymers containing poly(ethylene oxide) and polyethyleneimine blocks were prepared by cross‐linking polyethyleneimine with poly(ethylene oxide) terminated at both ends with Br atoms in DMSO. The experimental results show that the network density of the copolymer and the water absorption power thereupon can be efficiently controlled by the change of the amount of DMSO in the reaction system. Further modification was obtained by converting these copolymers into quaternary ammonium salts. The resulting quaternary ammonium salts exhibit enormously enhanced water absorption power. The absorption power of these quaternary ammonium salts in several organic solvents and in aqueous solutions containing Na+, Ca2+, Mg2+, or Fe3+ was also examined.
Viscometric behavior of ternary concentrated solutions of hydroxypropyl cellulose and ethyl cellulose in m‐cresol
Authors: Suto Shinichi , Kosaka Masato , Sugiura Terusada 
Published: April 2003

AbstractThe shear viscosity of blend solutions of hydroxypropyl cellulose (HPC) and ethyl cellulose (EC) in m‐cresol (both HPC/m‐cresol and EC/m‐cresol systems form lyotropic liquid crystals) was determined by cone‐plate‐type and capillary‐type viscometers. The textures for the same systems at rest and undergoing shear were also observed with a polarized microscope.At shear rate of 1 s−1, viscosity exhibited a maximum and a minimum with respect to temperature, and this suggested that the phase of the matrix dominated the viscometric behavior of the ternary systems; the blend composition dependence of the viscosity was not additive, and this suggested that HPC and EC were immiscible. At relatively high shear stress, the blend composition dependence of the viscosity greatly depended on the total polymer concentration of the solutions and was quite different from that at low shear rate; the texture of the anisotropic solutions was also different from that at low shear rate. Our findings suggested that the dependence of viscosity on shear and concentration for pure HPC solution was different from that for pure EC solution.
Experimental relations between physical structure and mechanical properties of a huge number of drawn poly(ethylene terephthalate) yarns
Authors: Heuvel H. M. , Lucas L. J. , Van den Heuvel C. J. M. , De Weijer A. P. 
Published: April 2003

AbstractThe results of a study of the relation between a number of mechanical properties of poly(ethylene terephthalate) (PET) yarns and their physical structure are presented. The relation was studied on a set of 295 drawn yarn samples, resulting from an exceptionally large variety in process conditions applied. The size of this experiment offered a unique opportunity to study the property–structure relation more extensively than ever before. Therefore, our understanding of the mechanical properties could be enriched with several new insights. A selection of seven yarn properties has been investigated. Five of them have been derived from the stress–strain curves and the remaining two are shrinkage and shrinkage force. The physical structure has been described with a set of five, statistically selected, parameters. Most of the yarn properties could very well be described in terms of these structure parameters. This description was performed by means of an artificial neural network, ANN. The type of calculation is completely naive, i.e., without any specific mathematical formulation for the relation concerned. The fitting results have been translated into physical aspects related to the well‐known molecular two‐phase model. The practical importance of a good physical understanding of yarn properties is that the essential possibilities and impossibilities of combinations of properties can far more easily be surveyed and understood. As a result, the efficiency of process developments can be substantially improved.
Synthesis and characterization of saturated and unsaturated copolyesters based on bis‐1,4‐(dicarboxymethoxy) benzene
Authors: Essawy S. A. , El‐Sawy A. A. , Mahmoud A. A. , Badr S. K. 
Published: April 2003

AbstractSaturated copolyester were prepared by copolyesterification of bis‐1,4‐(dicarboxymethoxy) benzene and phthalic anhydride with diethylene glycol, triethylene glycol, tetraethylene glycol, 1,4‐butane diol, 1,2‐propane diol, and 1,6‐hexamethylene glycol. Also, unsaturated copolyesters were prepared by copolyesterification of bis‐1,4‐(dicarboxymethoxy) benzene and maleic anhydride with the same glycols. All the copolyester resins obtained have been characterized and unsaturated copolyesters in the form of films were determined. IR and 1H‐NMR spectroscopy were used for both qualitative and quantitative analysis of the copolyesters resins and their hydrolyzate products, after curing with styrene. © 1992 John Wiley & Sons, Inc.
DC conduction in butyl rubber (IIR) loaded with carbon black
Authors: Abo‐Hashem A. 
Published: April 2003

AbstractCurrent–voltage characteristics of samples of butyl rubber loaded with two different types of carbon black have been studied at different temperatures in the voltage range 10–3 KV. The conduction mechanism was found to follow the conventional band approach followed by the hopping model for isobutylene isoprene rubber (IIR) mixed with 40 phr of fast‐extrusion furnace black (FEF) carbon black and the hopping model for IIR mixed with 50 phr of semireinforcing furnace black (SRF) carbon black. © 1992 John Wiley & Sons, Inc.
Chemical interactions at the interface between a carbon fiber and a boron trifluoride‐catalyzed epoxy matrix
Authors: Wang Shiping , Garton Andrew 
Published: April 2003

AbstractThe cure of a tetrafunctional epoxy resin (largely tetraglycidyldiaminodiphenylmethane, TGDDM), cross‐linked with diaminodiphenylsulphone (DDS) and boron trifluoride/ethylamine (BF3EA) catalyst, is affected in a complex fashion by the presence of an oxidized carbon fiber surface. If the fiber is aged in a humid environment (25°C, 95% humidity) before coating with the matrix, the affinity of the oxidized fiber surface for water leads to destruction of the catalyst and retardation of the cure. This retardation is noticeable at lower humidities if the polymer content of the composite is reduced to > 20%. For oxidized fibers that are stored under ambient conditions (40% humidity), the retarding effect of water is overwhelmed by the catalytic effect of the acidic fiber surface. This activates the latent catalyst, increasing the rate of epoxy consumption and the proportion of the epoxy–epoxy reaction relative to the epoxy–amine reaction. For the low‐humidity case, even though the rate of chemical reaction is increased, vitrification of the matrix is retarded, implying that there is less cross‐linking and more extended epoxy–epoxy sequences in the network. The proposed chemical changes in epoxy/carbon fiber composites were confirmed by analysis of model reactions in solution. © 1992 John Wiley & Sons, Inc.
Semi‐ and fully interpenetrating polymer networks based on polyurethane–polyacrylate systems. XI. The influence of polymerization temperature on morphology and properties
Authors: Hourston D. J. , Huson M. G. 
Published: April 2003

AbstractPolyurethane–poly(methyl acrylate) interpenetrating polymer networks (IPNs) of fixed composition (50/50) were prepared at 200 MPa and a range of temperatures. Decreased synthesis temperatures generally resulted in improved mixing of the two networks, although the sequence of formation of the two polymers was also important. No obvious improvements in physical properties resulted from the enhanced mixing. At high synthesis temperatures, the exothermic heat of polymerization of the methyl acrylate led to excessive temperatures, capable of degrading the already‐formed polyurethane network. This resulted in a deterioration in tensile strength and a decrease in hardness of the IPN. © 1992 John Wiley & Sons, Inc.
The mechanical behavior of blends of polyethylene, polypropylene, and an ethylene–propylene block copolymer at −20°C
Authors: Flaris Vicki , Stachurski Zbigniew H. 
Published: April 2003

AbstractCompatibilization is necessary for most binary blends which display poor mechanical properties. The addition of an ethylene–propylene block copolymer to a blend of isotactic polypropylene and linear low‐density polyethylene alleviates the problem of poor adhesion at the interface. This was observed through the improvement in overall performance of the blend. It was noted that it is not solely the “interfacial agent” which is responsible for the improvement in impact strength of this blend. © 1992 John Wiley & Sons, Inc.
Epoxy composites based on glass beads. I. Viscoelastic properties
Authors: Amdouni N. , Sautereau H. , Gerard J. F. 
Published: April 2003

AbstractThe viscoelastic behavior of glass beads composites are studied. Untreated, silane‐treated and elastomer‐coated glass beads were used, dispersed in a DGEBA–DDA–BDMA epoxy matrix. Using low frequency experiments, the three‐phase structure of coated glass bead composites is demonstrated. The characteristics of both the α and β relaxations of the epoxy networks are analyzed and discussed. The β relaxation is independent of volume fraction and glass treatment. On the contrary, the position of the α relaxation increases strongly with glass volume fraction and silane treatment. The introduction of the elastomer as a thin layer at the filler/matrix interface induces a large chain mobility, thus decreasing the temperature position of the α peak. © 1992 John Wiley & Sons, Inc.
The heterogeneous character of the dilute acid hydrolysis of crystalline cellulose. III. Kinetic and X‐ray data
Authors: Lin Chyong‐Huey , Conner Anthony H. , Hill Charles G. 
Published: April 2003

AbstractThirteen prehydrolyzed samples of cellulose, including native, mercerized, and regenerated materials were hydrolyzed in 1% and 1.5% sulfuric acid at 160, 170, and 180°C. Pseudo first‐order rate constants and weight average degrees of polymerization were determined for each sample. For all cellulose samples, data from several experiments were used to determine the dependence of the rate of hydrolysis on sulfuric acid concentration. The results obtained in this study indicate that Sharples' end‐attack model is consistent with kinetic data for the hydrolysis of cellulose II samples, but is not applicable to the hydrolysis of cellulose I samples. X‐ray diffraction analyses indicated that, for native and mercerized cellulose samples, structural changes during dilute acid hydrolysis are not significant. However, data for rayon indicated that such changes may need to be taken into account in analysis of the reaction kinetics.
Poly(butylene terephthalate)/high density polyethylene alloys. II. Mechanical properties and rheology
Authors: Joshi M. , Maiti S. N. , Misra A. 
Published: April 2003

AbstractAlloys of poly(butylene terephthalate) (PBT) and high density polyethylene (HDPE) in 80 : 20 ratio were prepared using a polyethylene‐based ionomer as a compatibilizer. The effect of the addition of this compatibilizer on mechanical and rheological properties of the PBT/HDPE blends was examined. The mechanical properties studied were tensile, flexural, and impact properties as a function of ionomer content. Ultimate mechanical properties showed significant improvement on addition of ionomer. This has been attributed to an increase in the interfacial adhesion between the two phases in the presence of the compatibilizer. Rheological measurements showed that shear viscosity increased for the blend with the addition of the compatibilizer. An explanation for this behavior is presented on the basis of the theory of emulsions.
Crystallization of fiber‐reinforced poly(phenylene sulfide) composites. II. Modeling the crystallization kinetics
Authors: Desio Glenn P. , Rebenfeld Ludwig 
Published: April 2003

AbstractThe kinetic data obtained by differential scanning calorimetry for the isothermal crystallization from the melt of unreinforced poly(phenylene sulfide) (PPS) and of model carbon, aramid, and glass fiber‐reinforced PPS composites has been analyzed and modeled on the basis of the Avrami equation. The classical Avrami model provided a good description of the volume fraction crystallized for PPS and for those composites that did not exhibit transcrystallinity in thin‐film specimens. Nonlinear Avrami behavior was observed for those composite systems that did exhibit transcrystallinity, for which parallel and series dual Avrami models were used. A series crystallinity model, which corrects the volume fraction crystallized for structural, imperfections, was applied to all the systems, providing a reasonable modeling of the data. In this model, we postulate an initial primary crystallization followed by a secondary crystallization. The temperature dependencies of the Avrami rate constants were analyzed through Arrhenius relationships, and the resultant activation energies and frequency factors were interpreted in terms of nucleation and growth phenomena. We found the frequency factor for primary crystallization to be indicative of the nucleating abilities of the fiber surfaces and to correlate with the presence of transcrystallinity.
Mechanical properties of poly(ethylene terephthalate) fibers imparted hydrophilicity with aminolysis
Authors: Fukatsu Kazuhiko 
Published: April 2003

AbstractPoly(ethylene terephthalate) fibers were aminolyzed with hydradine hydrate and ethylenediamine. The moisture regain of aminated fibers increased with increasing weight loss. It was suggested that the aminolysis reaction took place mainly in the amorphous regions. This leads to an increase of the accessibility of moisture. The mechanical properties of the aminated fibers were reported as a function of the weight loss by the aminolysis reaction; tenacity, stiffness, and wrinkle recovery were considered and discussed with regard to fine structures. General trends of decreasing tenacity, stiffness, and wrinkle recovery with increasing weight loss were observed for fibers aminated by hydrazine hydrate and ethylenediamine. Within this trend, there is difficulty for application of aminolysis that will not provide superior performance in the polyester fiber property such as tensile strength, stiffness, and wrinkle recovery.
Polymerization of acrylamide in the presence of calcium sulfate dihydrate and calcium sulfate hemihydrate
Authors: Stav Elisha , Bentur Arnon , Kohn David H. 
Published: April 2003

AbstractThe homopolymerization of acrylamide in water alone and also in the presence of calcium sulfate dihydrate and of calcium sulfate hemihydrate has been studied. Polymerizing acrylamide with the redox pair potassium persulfate—sodium bisulfite, the rate increased steadily with increasing initiator concentration. In the presence of up to 25% dihydrate, the rate was like that of acrylamide alone. However, when adding the “reactive” hemihydrate that is hydrated to the dihydrate concurrently with the progressing polymerization, the rate is somewhat slower in comparison with the two other systems. For determination of the compositions of the various reaction products, a method combining DTA and XRD data has been developed.
Batch and semicontinuous emulsion copolymerization of vinylidene chloride and butyl methacrylate. II. Physical and mechanical properties of copolymer latex films
Authors: Lee K. C. , El‐Aasser M. S. , Vanderhoff John W. 
Published: April 2003

AbstractVinylidene chloride (VDC)–butyl methacrylate (BMA) copolymer latex films of various compositions (83 : 17, 60 : 40, 33 : 67 in mol %), prepared by batch and semicontinuous processes, were investigated for their physical properties by infrared spectroscopy, 13C solidstate NMR spectroscopy, X‐ray diffraction, solubility in various solvents, differential scanning calorimetry (DSC), and water vapor transmission rates (WVTR), and for their mechanical properties by dynamic mechanical spectroscopy (DMS), and tensile strength measurements. Semicontinuous latex films were found to be homogeneous in composition and amorphous in character. On the other hand, batch latex films containing high VDC monomer content were heterogeneous in composition and crystalline in character. These differences were found to reflect the effect of mode of monomer addition during the emulsion polymerization process, and correlated well to the results on kinetics, colloidal, and surface properties of the VDC‐BMA copolymer latexes, as described in the first part of this study.
Diffusion of acids into epoxy resin compositions
Authors: Kalenda P. 
Published: April 2003

AbstractThe study deals with the diffusion of aqueous acid solutions into diethylenetriamine‐hardened epoxy resins. The results obtained indicate that the diffusion of acids into epoxy resins is affected heavily by the epoxy resin structure, the epoxide group content in the respective resin, and thus also by the molecular mass of the resin concerned. A straight‐line dependence has been found between the diffusion coefficient of acids and the epoxide group contents in the resin.
Polymer matrix controlled release systems: Influence of polymer carrier and temperature on water uptake and protein release
Authors: Sheppard Norman F. , Madrid M. Yvette , Langer Robert 
Published: April 2003

AbstractThe release of bovine serum albumin (BSA) from two types of ethylene‐co‐vinyl acetate (EVAc) polymer matrices was studied over the temperature range 4–50°C. Protein release and weight change of the matrices were evaluated in uitro. The copolymers were characterized using differential scanning calorimetry (DSC) and thermomechanical analysis (TMA). During release, the devices initially exhibit a rapid increase in weight to a maximum, followed by a more gradual decrease for the duration of the release. The time to the maximum weight and the magnitude of the maximum weight gain are temperature dependent. These effects are related to the temperature‐dependent diffusivity of the BSA and elastic modulus of the EVAc. The DSC and TMA reveal melting of the crystalline phase of the polymer. The corresponding loss of mechanical integrity of the polymer leads to anomalous weight gains at these temperatures. The observed swelling and release is explained by a model in which the osmotic pressure of the protein within the pore network causes elastic deformation of the polymer matrix.
Independent control of mechanical and chemical properties of monodispersed polystyrene–divinyl benzene microspheres by two‐step polymerization
Authors: Kobayashi K. , Senna M. 
Published: April 2003

AbstractMonodispersed polystyrene (PS) latices of the particle size ranging between 4 and 10 μm were prepared by a conventional dispersion polymerization technique using poly‐(acrylamide) as a stabilizer. Styrene containing 2–20% of divinyl benzene (DVB) was subsequently polymerized on the surface of the latex by a seeded polymerization technique for the purpose of modifying the thermo‐mechanical and chemical properties of the microspheres. The softening temperature during hot pressing and the resistance against the dissolution on swelling in toluene or methyl ethyl ketone increased with increasing amount of DVB. The state of seeded polymerized particles was revealed to depend more on the total amount than the composition of the monomer added. By using the present technique, it is possible to prepare chemically stable, monodispersed microspheres with their diameters and softening temperature varying from 4.5 to 12 μm and from 106 to 126°C, respectively, with a free combination by choosing the appropriate dispersion polymerization condition and the amount of DVB during subsequent seeded polymerization.
Phosphorylation of the waste products from the dimethyl terephthalate production with the dimethyl ester of the 1,2‐di(methoxycarbonyl)ethane phosphonic acid
Authors: Todorov K. , Georgieva A. , Troev K. , Borisov G. 
Published: April 2003

AbstractIt is demonstrated that the dimethyl ester of 1,2‐di(methoxycarbonyl)ethane phosphonic acid can be used as a phosphorylating agent of the production wastes of dimethyl terephthalate. The products obtained have different characteristics depending on the mode of phosphorylation.
Analysis of the internal crazes in notched SAN
Authors: Shin E. S. , Hiltner A. , Baer E. 
Published: April 2003

AbstractCrazing in styrene–acrylonitrile copolymer (SAN) under a triaxial stress state was examined. The damage zone that formed ahead of a semicircular notch under slow tensile loading consisted of two kinds of crazes: internal notch crazes that grew out from the notch root and discontinuous surface crazes. Examination of the damage zone in the optical and scanning electron microscopes revealed that the internal notch crazes sometimes extended through most of the thickness but never penetrated the free surfaces, whereas the surface crazes penetrated about 10–50 μm inward from the surface. Initially, the internal craze tips defined a crescent‐shaped zone. The plane strain elastic stress distribution at the zone boundary satisfied a constant mean stress condition, and the critical mean stress for craze tip growth was determined to be about 35 MPa. This value varied slightly for different resins but was independent of thickness. Propagation of the internal notch crazes occurred in a straight line parallel to the minor principal stress vector at the point of origin on the notch surface, whereas the surface crazes followed the minor principal stress trajectories. The presence of the internal notch crazes resulted in significant stress redistribution, the stress redistribution was described quantitatively using both the deviation of the craze trajectory from the minor principal stress trajectory, and the deviation of the zone shape from the critical elastic mean stress condition.