bluuebunny/crossref_metadata_2025_split huggingface dataset:
Environmental stress cracking of poly(acrylonitrile‐butadiene‐styrene)
Authors: Kawaguchi Takafumi , Nishimura Hiroyuki , Miwa Fumiaki , Abe Kazuhiro , Kuriyama Takashi , Narisawa Ikuo 
Published: April 2004

AbstractThe environmental stress cracking (ESC) of acrylonitrile‐butadiene‐styrene (ABS) copolymer caused by a non‐ionic surfactant (poly‐oxyethylene alkylether) was studied by constant‐load tensile creep tests and edge crack tension (ECT) tests. The fracture surfaces were investigated by a scanning electron microscope (SEM) and the morphology of the crack tip was investigated by a transmission electron microscope (TEM). It was found that the results of the creep tests performed in the non‐ionic surfactant were very different from those performed in air. SEM images of the fracture surfaces showed that there were three different mechanisms of fracture and that specimens had a tendency to rupture by ESC when the stress was small. The results of the ECT tests and the TEM images showed that the change in the mechanism of the fracture was attributable to the change of morphology at the crack tip.
Effect of compatibilizers on mechanical properties and morphology of in‐situ composite film of thermotropic liquid crystalline polymer/polypropylene
Authors: Bualek‐Limcharoen Sauvarop , Samran Jareerat , Amornsakchai Taweechai , Meesiri Wiriya 
Published: April 2004

AbstractAn in‐situ composite film of a thermotropic liquid crystalline polymer (LC3000)/polypropylene (TLCP/PP) was produced using the extrusion cast film technique. The compatibilizing effect of thermoplastic elastomers, styrene‐ethylene butylene‐styrene (SEBS), maleic anhydride grafted SEBS (MA‐SEBS), and maleic anhydride grafted polypropylene (MA‐PP) on the mechanical properties and morphology of the TLCP/PP composite films was investigated. It was found that SEBS provided a higher value of tensile modulus than MA‐SEBS, which in turn was higher than MA‐PP, despite the expected stronger interaction between the MA chain and TLCP. The observation of the morphology under optical and scanning electron microscopes suggested that all three compatibilizers helped improve the dispersion of the TLCP fibers and increased the fiber aspect ratio to a different extent. The fractured surface of the specimens showed more fiber breakage than pull‐out when a compatibilizer was added, which suggested the improvement of interfacial adhesion. The surface roughness of fibers with an added elastomeric compatibilizermay also provide mechanical interlocking at the interface. It is suggested that the increase in the viscosity ratio of TLCP/PP due to the added elastomeric compatibilizer, SEBS and MA‐SEBS, compared with the thermoplastic compatibilizer, MA‐PP, is more effective in improving the composite mechanical properties.
The adhesion between electrolessly deposited copper and a photoimageable polymer
Authors: Suzuki Masao , Kawamoto Mineo , Takahashi Akio 
Published: April 2004

AbstractWe investigated the relationship between the peel adhesion of copper, deposited by electroless plating, to a photoimageable polymer and the time of chemical etching before plating. Mechanical interlocking is generally considered as being the adhesion mechanism between deposited metals and substrates. However, we found that the peel strength decreased with an increase in the etching time though the polymer roughness did not change. The glass transition temperature of the photoimageable polymer became lower as the etching time increased. The pretreatment not only roughened the surface of the photoimageable polymer, but also affected the bulk polymer and the adhesion.
Extrusion characteristics of thermoplastic melts containing fluoropolymers
Authors: Lee Eonseok , White James L. 
Published: April 2004

AbstractThis paper investigates the influence of fluoropolymers on the extrusion characteristics of three different thermoplastic melts. The presence of a small amount of fluoropolymer reduced the pressure drops, extrudate swell, and retarded the onset of surface defects in linear low density polyethylene (LLDPE), while little or no effect was found in polystyrene (PS) and polyamide 12 (PA 12). Among the fluoropolymers investigated in this study, vinylidene fluoride‐hexafluoropropylene (VDF‐HFP) copolymer was the most effective additive in reducing the pressure drop and extrudate distortion of LLDPE, polyvinylidene fluoride (PVDF) intermediate, and tetrafluoroethylene‐hexafluoropropylene (TFE‐HFP) copolymer exhibited the least effectiveness. Contact angle measurements on the die surface indicated that all fluoropolymers preferentially deposit on the die surfaces during the extrusion of LLDPE and PS blends with small amounts of fluoropolymers.
Long fiber reinforcement of polypropylene/polystyrene blends
Authors: Inberg J. P. F. , Hunse P. H. , Gaymans R. J. 
Published: April 2004

AbstractThe recycling of inseparable polymer mixtures usually results in blends with poor mechanical properties. A mixture of PP and PS was taken as a model compound for a recyclate. The effect of adding glass fibers to a mixture of PP/PS (70/30) was studied, with special attention to long glass fiber reinforcement. Test specimens were made in three different ways: by dry blending (direct injection molding), mild compounding with a single screw extruder, and compounding with a twin screw extruder. The fiber concentration was varied from 0 to 30 wt%. The fiber lengths were determined to investigate fiber attrition. The fiber lengths in the samples were 1.09 mm for dry blending, 0.72 mm for single screw compounding, and 0.33 mm for twin screw compounding. The mechanical behavior was studied by unnotched and notched Izod impact and tensile tests. The PP/PS blend had a low fracture strain and low unnotched Izod impact strength compared with a PP homopolymer. With an increasing fiber concentration and fiber length, the modulus, tensile strength, and particularly the impact strength increased. With a 30 wt% glass fiber of the long fiber compound (dry blended), the modulus was raised by a factor of 3.5, the fracture stress by a factor of 2.5 and the unnotched Izod impact strength by a factor of 10. The product quality as judged by the scatter of the data was best for the twin screw compound and poorest for the dry blend. Compounding with a single screw extruder gave fairly constant injection molding product properties, combined with excellent mechanical properties.
In‐line residence time distribution of dicarboxylic acid oligomers/dioxazoline chain extension by reactive extrusion
Authors: Chalamet Yvan , Taha Mohamed 
Published: April 2004

AbstractPolyesteramides were prepared by reactive extrusion by a condensation reaction of a fatty dicarboxylic acid [Unichema Pripop (1009) (C36)] or a carboxyl terminated polyamide 12 (CTPA 12) and a dioxazoline coupling agent [(1,3‐Phenylene)‐bis(2‐Oxazoline), (OO)]. The Residence Time Distribution (RTD) was measured using different fillers as in‐line ultrasonic detectable tracers and UV detectable reactive or nonreactive tracers. The apparent RTDs measured using ultrasonic detectable tracers were very different. The analysis of the reaction product and comparing RTDs measured using ultrasonic and UV tracers showed that the addition of a tracer had no effect on the reactive system and that most of the ultrasonic tracers did not flow in an identical manner to the reactive system. No direct correlation was obtained between the rheological or rheokinetic behaviors of the monomers or the reactive system and the apparent RTD. The RTD was obtained by using calcium carbonate as in‐line ultrasonic detectable tracers and UV detectable reactive or nonreactive tracers.
Essential fracture work of short fiber reinforced polymer blends
Authors: Wong Shing‐Chung , Mai Yiu‐Wing 
Published: April 2004

AbstractShort glass fiber reinforced (SGFR) PA6,6/PP blends with 20 wt% styrene‐ethylene/butylene‐styrene triblock copolymers (SEBS) grafted with different levels of maleic anhydride (MA) were studied using both the essential work of fracture (EWF) and J‐integral fracture toughness techniques. Good linearity was found between the plane strain specific fracture work, Wf, and the ligament length, l, in single‐edge notched bend (SENB) specimens. The two fracture mechanics parameters were compared and there was good agreement between the J‐integral fracture initiation toughness, JIC, and the specific essential fracture work, WIe. The skin‐core morphology characteristic of injection molded short fiber reinforced thermoplastics (SFRT) was also revealed using the EWF approach.
Characterization of recycled cellulose by dynamic and isothermal thermogravimetry investigations
Authors: Devallencourt C. , Saiter J. M. , Capitaine D. 
Published: April 2004

AbstractIsothermal thermogravimetric measurements were performed on recycled cellulosic materials. The kinetic parameters were determined with the Avrami‐Erofe'ev equation from two different ways. The first one consists of the determination of n from the slope of the variations of ln(–ln(1–α)) versus ln(t) and apparent activation energy ΔE from the slope of ln(k(T)) versus 1/T. The second one also gives the values of n and ΔE from a numerical fit of the experimental data. Both methods lead to the same results and show that the reaction order of the degradation process of the cellulose is close to unity. The value of this reaction order allows the interpretation of the dynamic thermogravimetry data with the Broido method. Using this method on a series of recycled cellulose with different content of chemical and mechanical paper pulps, we show that the apparent activation energies depend linearly onto paper pulp ratio.
Measurement of Tg in epoxy resins by DSC—effects of residual stress
Authors: Wang Hongbing , Siow Kok Siong 
Published: April 2004

AbstractDifferences in the glass transition temperatures (Tg) of epoxy resins were observed when their samples for differential scanning calorimetry (DSC) measurements were prepared by two different methods. The differences (in Tg) are believed to be due to the effects of interfacial residual stress, which is present only in the samples of lower Tg prepared with the formation of a “chemical” contact between epoxy resin and aluminum (pan) which have mismatched thermal expansion coefficients. Both types of the samples also showed, respectively, lower Tg when they were prepared by a fast‐cooling process than when they were prepared by a slow‐cooling process. This suggests that matrix residual stress, which is present in both types of the samples, as well as interfacial residual stress, has similar effects on the Tg of epoxy resins. This conclusion is substantiated by the results of the change of contact pattern and the freezing stress experiments.
Bubble growth in reaction injection molded parts foamed by ultrasonic excitation
Authors: Youn Jae R. , Park Hyeog 
Published: April 2004

AbstractProcessing of microcellular foam was studied for polyurethane. Assuming that the bubble growth is controlled by diffusion, theoretical prediction was carried out numerically to understand the bubble growth mechanism in the cavity during mold filling. Final bubble sizes were also predicted by considering the gelation time and the diffusion boundary. Viscosity change of the mixed polyurethane resin during polymerization reaction was predicted by considering reaction kinetics. The gelation time was determined to terminate the numerical calculation. The diffusion boundary was predicted based on the number of nucleated bubbles that had been determined both theoretically and experimentally. For processing of polyurethane foam by reaction injection molding, ultrasonic excitation was applied to the mixture of polyol and isocyanate. The polyol resin was supersaturated with nitrogen gas at an elevated pressure and ultrasonic excitation was applied to the mixture after impingement mixing of two components of the selected polyurethane system. Bubble nucleation was induced by the ultrasonic excitation and the bubbles were grown as the gas was supplied to the bubble from the resin.
Dynamic‐Mechanical properties and composition of longitudinal polymer liquid crystals
Authors: Woelke Ralf , Hess Michael 
Published: April 2004

AbstractThe temperature dependence of the dynamic‐mechanical behavior of different longitudinal polymer liquid crystals with short, branched spacers was analyzed and compared with results from calorimetric measurements. The combination of different techniques is necessary for interpretation. Torsional braid analysis provides advantages in the low‐temperature range.
Synthesis and physical characterization of semi‐IPNS of linear polyurethane and heterocyclic polymer network
Authors: Bartolotta Antonino , Marco Gaetano Di , Carini Giuseppe , D'Angelo Giovanna , Tripodo Gaspare , Fainleib Alexander M. , Slinchenko Elena A. , Shtompel Vladimir I. , Privalko Valery P. 
Published: April 2004

AbstractSemi‐interpenetrating polymer networks (semi‐IPN) of linear polyurethane (LPU) and heterocyclic polymer network (HPN) were characterized by IR spectroscopy, small‐angle X‐ray scattering, differential calorimetry with diathermal shells (temperature interval 130‐500 K), and dynamic mechanical analysis (temperature interval 150‐500 K and frequency range 0.3‐30 Hz). The main results obtained may be summarized as follows: (1) The affinity of HPN towards the soft LPU microphase is responsible for the absence of large‐scale heterogeneity of semi‐IPNs on their base (at least, at low HPN/LPU ratios). (2) Phenomenological analysis of small‐scale, Arrhenius‐like subglass relaxations (γ1 and γ2 in LPU and in HPN, respectively) revealed little interference of HPN with relaxation centers (RCs) of LPU in semi‐IPNs, while the local environment of RCs in HPN, on the contrary, strongly depended on semi‐IPN composition.
Microstructure and properties of random heterogeneous materials: A review of theoretical results
Authors: Quintanilla J. 
Published: April 2004

AbstractWe present an overview of some theoretical results that have been obtained to rigorously bound the effective conductivity and effective elastic moduli of random heterogeneous materials. These bounds are obtained through the appropriate use of integrals over certain microstructure functions that capture essential morphological information about random materials. Such a characterization has been obtained analytically for several models, including fully penetrable spheres, totally impenetrable spheres, and the “cherry‐pit” model. These analytical techniques—characterizing the microstructure and using this information to bound the effective properties—will undoubtedly be useful in obtaining sharper bounds on the effective properties of polymers. While we present some advanced ideas and methods, an attempt will be been made to elucidate these methods for the nonexpert.
Laser light‐scattering studies of soluble high performance fluorine‐containing polyimides
Authors: Kwan Simon Chi Man , Wu Chi , Li Fuming , Harris Frank W. , Cheng Stephen Z. D. 
Published: April 2004

AbstractTwo sets of soluble high performance polyimides synthesized from 2,2′‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2′‐(trifluoromethyl)‐4,4′‐diaminobiphenyl diamine (PFMB), and from 2,2′‐bis(trifluoromethyl)‐4,4′,5,5′‐biphenyl‐tetracarboxylic dianhydride (HFBPDA) and 2,2′‐(trifluoromethyl)‐4,4′‐diaminobiphenyl diamine (PFMB) have been investigated by static and dynamic laser light scattering (LLS) in tetrahydrofuran (THF) at 30°C. The calibrations, for 6FDA‐PFMB: <Rg> (nm) = 3.87 × 10−2<Mw>0.568, <Rh> (nm) = 2.38 × 10−2<Mw>0.560and <D> (cm2/s) = 2.13 × 10−4<Mw>−0.560; for HFBPDA‐PFMB: <Rg> (nm) = 2.24 × 10−2<Mw>0.626, <Rh> (nm) = 1.27 × 10−2<Mw>0.621and <D> (cm2/s) = 3.99 × 10−4<Mw>−0.621, have been established, where <M2>, <Rg>, <Rh> and <D> are the weight‐average molar mass, the root mean squarez‐average radius of gyration, thez‐average hydrodynamic radius and thez‐average translational diffusion coefficient, respectively. A combination of <Mw> and the translational diffusion coefficient distributionG(D) leads to the calibrations ofD(cm2/s) = 2.41 × 10−4M−0.564andD(cm2/s) = 6.16 × 10−4M−0.656for 6FDA‐PFMB and HFBPDA‐PFMB, respectively, whereDandMcorrespond to monodisperse species. With these calibrations, we can convert a translational diffusion coefficient distributionG(D) into a corresponding molar mass distributionfw(M). On the basis of the Kratky‐Porod wormlike chain model, the persistence lengths (q) were found to be ˜ 3.3 nm and ˜ 4.5 nm, respectively, for 6FDA‐PFMB and HFBPDA‐PFMB, which indicates that both polyimide chains have an extended conformation. In addition, <Rg> / <Rh> ˜ (1.7‐1.9) shows that they are in coil conformation. Therefore, we conclude that both polyimides have an extended coil conformation.
Polyurethane + polyacrylate latex mixtures: Synthesis, characterization and properties
Authors: Travinska Tamara V. , Lipatov Yuri S. , Maslak Yuri V. , Rosovitsky Valeri F. 
Published: April 2004

AbstractA series of polyurethane + polyacrylate latexes has been synthesized by putting different quantities of polyacrylate dispersion into an acetone solution of an anionic polyurethane prepolymer with terminal isocyanate groups. Colloid‐chemical and rheological properties of these systems have been investigated. The sorption of solvent vapors by mixtures of polyurethane + polyacrylate latexes has been studied. Some thermodynamical parameters including partial Gibbs functions of the solvent, individual polymers and their mixtures, and the Gibbs function of mixing polyurethane ionomer and acrylate copolymer have been calculated. Structureproperties relationships of the polyurethane + polyacrylate latexes were studied by dynamic mechanical analysis. Effects of varying the composition on the mechanical properties have been determined.
Evaluation of paracrystallinity in blown polyethylene films by generalized Clausius‐Mosotti equation
Authors: Bernabeu E. , Boix J. M. 
Published: April 2004

AbstractThe degree of paracrystallinity in several samples of low‐density blown polyethylene was estimated by assuming that there was a paracrystalline zone at the boundary between the amorphous and crystalline zones. The paracrystallinity was quantified by applying a generalization of the Clausius‐Mosotti equation and using the mean values of the ordinary and extraordinary refractive indices, previously calculated, through solving a special Bruggeman's equation. The final results are consistent with the values found in literature, where the degree of paracrystallinity is considered to be practically identical to the mean paracrystalline distortion parameter in this specific zone where these polymers are found.
Low temperature cure of vinyl ester resins
Authors: Li Ling , Sun Xiudong , Lee L. James 
Published: April 2004

AbstractVinyl ester resins are well known for their versatility as a composite matrix. With the development of a promising room temperature molding technology, vacuum‐assisted resin transfer molding, e.g. Seemann Composite Resin Infusion Molding Process (SCRIMP), the processability of vinyl ester resins at low temperatures has attracted considerable attention from the composite industry. The objective of this paper is to provide a better understanding of the reaction kinetics of this resin system at low temperatures. In this study, a differential scanning calorimeter (DSC) coupled with a Fourier transform infrared (FTIR) spectrometer was employed to measure the reaction profile of a vinyl ester resin with different promoter and styrene contents. A kinetic model based on the free radical co‐polymerization mechanism was developed for simulating the reaction rates and conversions of styrene vinyl and vinyl ester vinylene groups. The model parameters were determined from several FTIR experiments under isothermal conditions. This model, in conjunction with heat transfer analysis, was able to successfully predict the temperature profiles during curing in two SCRIMP molding cases based on groove type resin distribution system.
Numerical analysis of notch‐tip fields in rubber‐modified epoxies
Authors: Al‐Abduljabbar A. , Pan J. 
Published: April 2004

AbstractIn this work, the near‐tip fields in notched specimens of pressure‐sensitive nonporous and porous materials are investigated by finite element analysis. The specimen geometry and material properties are adopted from the corresponding experiments on rubber‐modified epoxies. The Drucker‐Prager yield criterion is first used to describe the yielding of nonporous materials. The yielding behavior of porous materials is based on a generalized Gurson yield criterion. The yield criterion for porous materials accounts for both the matrix material pressure sensitivity and the macroscopic pressure sensitivity due to porosity. Modifications are made on the yield criterion under negative mean stresses in order to account for the specific loading and geometry of the specimen. The computational results are compared with observed experimental cavitation zones and intense shear zones near the notch tip in specimens. Moreover, the near‐tip fields and crack initiation sites ahead of the notch tip related to the volume fraction of rubber particles are investigated. The computational results suggest that the lowering of the mean stress ahead of the tip in rubber‐modified epoxies with higher volume fractions of rubber changes the fracture mode from being controlled by high mean stresses at the elastic‐plastic boundary to being controlled by large plastic strains closer to the notch tip.
Conformational motions in immiscible blends of polycarbonate and styrene‐acrylonitrile copolymers
Authors: Belloch G. Pérez , Sanchez M. Salmerón , Ribelles J. L. Gómez , Pradas M. Monleón , Dueñas J. M. Meseguer , Pissis P. 
Published: April 2004

AbstractBlends of commercial bisphenol‐A‐polycarbonate and styrene‐acrylonitrile copolymers were prepared by precipitation in ethanol from the solution in methylene chloride in order to eliminate the low molecular weight substances contained in the commercial polymers, specially the oligomers contained in commercial SAN copolymers. Two glass transitions appear in the DSC thermograms of the blend at the same temperatures as in the pure components which, in principle, indicates that the blend consists of two phases formed by pure PC and pure SAN. In order to detect small changes in the glass transition process that could be indicative of different mobility of the polymer chains in the blend with respect to the pure polymers, blends of different compositions were subjected to different thermal treatments that included annealing at temperatures below both glass transitions, and then the DSC thermograms were recorded. A broadening in the peaks shown by the cp(T) curves measured on annealed samples in the zone of the PC transition is detected while no significant differences are shown by the glass transition of the San phase of the blend with respect to pure SAN copolymer. Dielectric relaxation experiments in the frequency domain (from 100 to 3·106Hz) were carried out on the blends. The dielectric relaxation spectrum in the zone of the SAN main relaxation process was fitted with the stretched exponential equation showing no significant difference between the blends and the pure SAN copolymer. The region of the main relaxation process of PC was not analyzed due to the small polar activity of PC and the overlapping with the relaxation of the SAN phase.