bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of polymer characteristics and melt‐spinning conditions on the production of fine denier poly(ethylene terephtalate) fibers. Part I. Rheological characterization of PET polymer melt
Authors: Kiang Chang T. , Cuculo John A. 
Published: April 2003

AbstractThe rheological characterization of four poly(ethylene terephtalate) (PET) polymers, with viscosity average molecular weight ranging from 2.7 × 104 to 7.1 × 104, has been performed in the Instron capillary rheometer. The apparent elongational viscosity was obtained from the shear flow and entrance pressure data, following the methods proposed by Cogswell and Binding in contraction flow experiments. The PET polymers showed a tension thinning behavior in the deformation rate range of 300–3000 s−1 employed in this study. These results were explained on the basis of the network model. Polymers with similar behavior in shear may be distinct in elongational and may lead to distinct polymer processability. Polymers with lower apparent elongational viscosity level were shown to allow spinning of finer denier fibers, which is determined by the polymer spinnability.
Protein‐dispersed liquid crystals
Authors: Hermel H. , Seeboth A. 
Published: April 2003

AbstractNematic liquid crystals (LC) were embedded in a highly structured gelatin film as the discrete phase in the form of droplets. Thereby, the gelatin matrix forces a preferred orientation of the LC molecules in the droplets, initiated by the interaction between the triple helices of gelatin and the LC at the interface protein/LC. This is explained on a molecular level by the formation of a supramolecular structure at the interface, which is a germ for the continued preferred orientation of the mesogenes inside the droplets.
Polyurethane elastomers based on novel polyether macrodiols and MDI: Synthesis, mechanical properties, and resistance to hydrolysis and oxidation
Authors: Gunatillake Pathiraja A. , Meijs Gordon F. , Rizzardo Ezio , Chatelier Ronald C. , McCarthy Simon J. , Brandwood Arthur , Schindhelm Klaus 
Published: April 2003

AbstractNovel polyurethane elastomers based on 4,4′‐diphenylmethanediisocyanate, 1,4‐butanediol, and polyether macrodiols that have 6, 8, or 10 methylene groups between the ether oxygens were prepared by two‐step solution polymerization. Their mechanical properties and degradation resistance were compared with poly(tetramethylene oxide)‐based polyurethanes. The new polyurethanes were more resistant to hydrolysis and to hydrogen peroxide‐induced oxidation than were the poly(tetramethylene oxide) ‐based materials. The poly(octamethylene oxide) ‐based polyurethane displayed good resistance to sodium hypochlorite. 1,2‐Diaminoethane chain‐extended polyurethane–ureas were also prepared using the macrodiols poly(hexamethylene oxide) and poly(octamethylene oxide). They were not thermally processable or solvent‐castable. Bulk synthesis of novel polyether polyurethanes yielded, in some cases, materials with improved mechanical properties compared with their solution‐polymerized counterparts. The outcome of the bulk syntheses was highly dependent, however, on reaction conditions and stoichiometry.
Polymerization of allyl esters derived from long‐chain fatty acids and palm olein
Authors: Gan L. H. , Ooi K. S. , Goh S. H. , Chee K. K. 
Published: April 2003

AbstractAllyl esters of palm olein, palmitic, and oleic acids were synthesized by transesterification and esterification methods using KOH and absolute H2SO4 as catalysts, respectively. Three allyl esters, namely, allyl palmitate, allyl epoxystearate, and epoxidized allyl ester of palm olein, were successfully polymerized in the presence of t‐butyl perbenzoate at 120°C to obtain oligomers with the average number of backbone atoms approximately equal to the number of skeletal atoms of the long‐dangling side chains. The kinetic data of polymerization were conformed to the rate equation proposed by other workers. No oxirane cleavage was detected during the chain reaction. The melting behavior of these comb‐shaped polymers was compared with that of their respective allylic monomers. The polymer of epoxidized allyl ester of palm olein exhibits a glass transition temperature at 204.4 K. The critical molecular weights of the polymers of allyl esters investigated are predicted to be not lower than 104.
Effect of blending on the crystallization behavior of PET
Authors: Nadkarni V. M. , Shingankuli V. L. , Jog J. P. 
Published: April 2003

AbstractThe crystallization of poly(ethylene terephthalate) (PET) in its blends with other thermoplastics such as poly(phenylene sulfide) (PPS), high‐density polyethylene (HDPE), poly(methyl methacrylate) (PMMA), aromatic polyamide, and a co‐polyester is reported. The nonisothermal crystallization and melting behavior of PET in its blends has been discussed. Because of differences between the melting/softening points of these polymers and the melting point of PET, the crystallization of PET takes place in the presence of solidified PPS in PET/PPS blends and in presence of the molten phase of the second component in the remaining blends. The observed changes in the melting and crystallization behavior are explained on the basis of the effect of the physical state of the second component. The results of the isothermal crystallization studies are consistent with these studies. The changes in the overall crystallization rate could be further explained in terms of the nucleation and growth processes occurring during the crystallization of PET using the isothermal crystallization data.
Interaction of polyamic acids and polyamic esters with copper and substituted polysilsesquioxane copolymers
Authors: Linde H. G. 
Published: April 2003

AbstractThe interactions of biphenyldianhydride–p‐phenylenediamine (BPDA–PDA) polyamic acid and ester polymers with copper and copper‐treated surfaces containing polysilsesquioxanes formed from 3‐aminopropyltriethoxysilane (APS) (or copolymers of APS and phenyltriethoxysilane) were compared by grazing‐incidence infrared spectroscopy. This investigation of a flexible dianhydride–stiff diamine copolymer compliments earlier work using the stiff dianhydride–flexible diamine polyamic acid and ester of pyromellitic dianhydride–oxydianiline (PMDA–ODA). Results support earlier findings that amic acids form thermally labile salts on copper but esters do not. Further, while APS forms a copper‐interactive film that insulates amic acid/metal interaction, APS–phenylsilsesquioxane copolymers create an interfacial region interactive with both copper and overlying polyamic acid.
Effect of shear rheology on PVDC and PE blend permeation behavior
Authors: Kirkpatrick D. E. , Mclemore J. K. , Wright M. A. 
Published: April 2003

AbstractThe morphology of an immiscible polymer blend is dependent on the flow properties of the components and the deformation fields to which the mixture is exposed. The barrier properties of an immiscible blend is dependent on the barrier properties of the components and the morphological structure of the blend. Therefore, the resulting permeation rate of these blends is dependent on the rheology of the component materials. Conversely, the morphology of these blends can be studied by measuring permeation rates of a probe molecule. The oxygen permeation rate of vinylidenechloride copolymers blended with polyethylene changes abruptly over a small composition range. In the absence of significant extensional flow fields, this change is due to a phase inversion, and its position in the composition range is dependent on the shear rheology of the components.
Enzyme membrane based upon polyamide‐6 for oil hydrolysis
Authors: Ceynowa J. , Adamczak P. 
Published: April 2003

AbstractThis work presents the preparation of the enzyme membrane based upon polyamide‐6 (PA‐6) destined for the hydrolysis of oils. The transport properties of the base PA‐6 membranes, i.e., their porosity and permeability coefficients, as well as the mode of their modification, aimed at the chemical binding of lipase molecules have been estimated. © 1992 John Wiley & Sons, Inc.
Evaluation of particle dispersion in polymer solids by oxygen plasma etching
Authors: Yang A. C.‐M. , Allen R. D. , Reiley T. C. 
Published: April 2003

AbstractA new technique using oxygen plasma etching was developed for studying the dispersion of filler particles in polymer solids. With this method, the organic polymer matrix is selectively etched from the top surface down into the bulk, revealing the dispersion state of the filler particles upon scanning electron microscopic analysis. A polymer composite, comprised of zinc oxide particles and a linear styrene‐n‐butylmethacrylate copolymer, was used to investigate the particle dispersion as a function of filler volume fraction. Preliminary data on the effect of a surfactant on filler dispersion is also discussed. © 1992 John Wiley & Sons, Inc.
Structural analysis of conveyor belts. II. Finite element approach
Authors: Parvini M. , Harandi J. N. , Kavousian A. , Soufian M. 
Published: April 2003

AbstractThe use of finite element analysis (FEA) in the design of a conveyor belt reduces the number of assumptions required in other methods. Although the problem is nonlinear (because of material property and geometry), a linear analysis produces comparable results. For handling the problem of large displacements, a prestrain method based upon a temperature gradient was used. The thickness of rubber interplies corresponding to minimum shear stress were determined for a number of three‐ply belts. © 1992 John Wiley & Sons, Inc.
Inverse gas chromatographic study of polymer blend interactions and their temperature dependence
Authors: Shi Z. H. , Schreiber H. P. 
Published: April 2003

AbstractThe temperature dependence of the thermodynamic interactions in blends of polypropylene and a fluorochemical was studied by inverse gas chromatography (IGC). A modified procedure has been proposed to evaluate the effective surface composition in polyblends. This shows that the low surface energy component preferentially concentrates in the surface region of blends. Moreover, the new procedure greatly reduces the probe‐to‐probe variation of χ23, a problem frequently encountered in thermodynamic applications of the IGC method. As a result, IGC may now be used with increased confidence for the determination of interaction thermodynamics in polymer systems over broad temperature ranges. © 1992 John Wiley & Sons, Inc.
New cation exchange composite based upon cellulose/melamine formaldehyde/citric acid reaction products
Authors: Ibrahim N. A. 
Published: April 2003

AbstractA new cation exchange composite was synthesized through the reaction of cellulose with both melamine formaldehyde precondensate and citric acid. Factors affecting the reaction such as reactants' molar ratios, liquor ratio, time, and temperature were reported. Reaction conditions were selected to prepare a cation exchange composite having a carboxyl content of 120 meq/100 g and a nitrogen percent of 22.1. Potentiometric titration of this exchanger showed that it behaves like a tribasic acid, and the strengths, pKa, of each stage of ionization are 5, 6.7, and 9.7, respectively. Water solubility as well as durability to use of the prepared exchanger were evaluated. © 1992 John Wiley & Sons, Inc.
Flow‐induced on‐line crystallization of rodlike molecules in fiber spinning
Authors: Yarin Alexander L. 
Published: April 2003

AbstractThe micromechanical description of nonisothermal flow‐induced crystallization of a polymeric liquid with rodlike molecules is the main part of the fiber spinning model described here. Solutions of the governing equations show that an increase in winding velocity leads to the appearance of an on‐line flow‐induced crystallization zone in a fiber. This zone manifests itself in accelerated formation (necking) due to the release of heat of crystallization which results in the decrease of viscosity. Liquid crystallinity grows very rapidly in the necking region, which, in turn, leads to the growth of viscosity after some minimal value, which finally arrests fiber deformation.
Pultruded fiber reinforced blocked polyurethane (PU) composites. I. Processability and mechanical properties
Authors: Chen Chin‐Hsing , Ma Chen‐Chi M. 
Published: April 2003

AbstractThis paper presents a proprietary process developed to manufacture polyurethane (PU) pultruded composites. The blocked isocyanate (NCO)‐terminated PU prepolymer synthesized in this study was prepared from ε‐caprolactam blocked blends of toluene diisocyanate (TDI) and branched polyester. The processability and mechanical properties of various fibers (glass, carbon, and Kevlar 49 aramid fiber) reinforced PU composites have been studied. From the investigation of the pot life of resins, the reactivity of resins, and fiber wet‐out, it was found that the blocked PU prepolymers with chain extender showed excellent processability for pultrusion. Results show that the mechanical properties (i.e., tensile strength, specific tensile strength, flexural strength, specific flexural strength, flexural modulus, and impact strength) increase with fiber content. Kevlar fiber/PU composites possess the highest impact strength and specific tensile strength, whereas carbon fiber/PU composites show the highest tensile strength, flexural strength, specific flexural strength, and flexural modulus. Experimental results of tensile strength of all composites except carbon fiber/PU composites follow the rule of mixtures. The deviation of property of carbon fiber/PU composite is due to fiber breakage during processing. Pultruded fiber reinforced PU composites showed excellent tensile and impact strength compared to other pultruded composites studied.
Pultruded fiber reinforced blocked polyurethane (PU) composites. II. Processing variables and dynamic mechanical properties
Authors: Chen Chin‐Hsing , Ma Chen‐Chi M. 
Published: April 2003

AbstractUnidirectional fiber reinforced blocked polyurethane (PU) composites have been prepared by the pultrusion process. The effects of processing variables on the mechanical properties and dynamic mechanical properties of fiber reinforced PU composites by pultrusion have been studied. The processing variables investigated included pulling rate (in‐line speed), die temperature, postcure time and temperature, and filler type and content. The dynamic mechanical properties of the composites produced by the process were studied utilizing dynamic mechanical spectrometer. Results show that the composites possessed various optimum pulling rates at different die temperatures. From the DSC data analysis, swelling ratio, and mechanical properties, the optimum die temperature was determined. It was found that the mechanical properties increase with filler content for various types of filler. The increasing of mechanical properties depends on the optimum postcure temperature and time. However, the properties decreased for longer postcure times since the composite materials were degraded. The glass‐transition temperature (Tg) increased slightly and the damping peak (tan δ) was broadened due to fiber reinforcement. The dynamic mechanical moduli (G′, G″) of pultruded PU composites are apparently higher than those of the matrices. The moduli (G′, G″) increase with increasing fiber and filler content, and the damping peak becomes broad. Effect of postcuring on the degree of crosslinking, Tg, and dynamic modulus will be discussed.
Synthesis, characterization, and curing of unsaturated polyamides derived from 2,6‐di(4‐carboxystyryl)pyridine and 2,6‐bis(4‐carboxybenzylidene) cyclohexanone
Authors: Mikroyannidis John A. 
Published: April 2003

AbstractTwo new series of heat‐curable polyamides were prepared utilizing the unsaturated dicarboxylic acids 2,6‐di(4‐carboxystyryl)pyridine (DCSP) and 2,6‐bis(4‐carboxybenzylidene)cyclohexanone (BCBC) as starting materials. They were prepared from the condensation of 4‐carboxybenzaldehyde with a half molar amount of 2,6‐dimethylpyridine or cyclohexanone, respectively. The dicarboxylic acids reacted with various aromatic diamines, utilizing triphenyl phosphite and pyridine as condensing agents, to yield polyamides. In addition, two model diamides were prepared by condensing the dicarboxylic acids with aniline. Characterization of starting materials, polyamides, and model compounds was accomplished by IR and 1H–NMR spectroscopy. The curing behavior of polyamides was investigated by DTA. Upon heat‐curing, the unsaturated polyamides were crosslinked through their olefinic bonds to afford insoluble, heat‐resistant resins. The thermal stability of the resins was evaluated by TGA and isothermal gravimetric analysis (IGA). The cured resins were stable up to 310–322°C in N2 or air and afforded anaerobic char yield of 57–69% at 800°C.
Hydrophilic and adhesive properties of polyethylene plates grafted with hydrophilic monomers
Authors: Yamada Kazunori , Tsutaya Hideyo , Tatekawa Shigeaki , Hirata Mitsuo 
Published: April 2003

AbstractThe photograftings of methacrylic acid (MAA), acrylic acid (AA), methacrylamide (MAAm), and acrylamide (AAm) as hydrophilic monomers onto polyethylene (PE) plates were carried out in the liquid phase. The contact‐angle measurement and the surface analysis by ESCA reveal that the grafted amount at which the PE surface was fully covered with grafted chains increased in the order of MAA > AA > MAAm and was almost the same as that at which contact angles became constant. The grafting of AAm was not sufficient to modify the surface properties of PE. But AAm required the smallest grafted amount to obtain the same adhesive strength as that of the other monomers. The α‐methyl and/or carboxyl groups were required to obtain a high grafted amount. The cos θ value of water on AA‐g‐PE surfaces reached a maximum around 0.02 mmol/cm2 and then decreased. It was confirmed to be caused by cohesion of grafted poly(acrylic acid) (PAA) chains due to the hydrogen bond. For all the monomers used, the adhesive strength increased with the grafted amount. As the concentration of the MAA monomer increased on grafting, at a higher grafted amount, the grafted layer absorbed water more rapidly and the PE plates themselves broke. For AA‐ and MAAm‐g‐PE plates, the amount of absorbed water increased linearly with the grafted amount irrespective of monomer concentration.
Polyvinylpyridine–ethanol systems
Authors: Akin H. , Hasirci N. 
Published: April 2003

AbstractPolymeric matrices of poly(2‐vinylpyridine) were prepared with application of gamma irradiation to its ethanolic solutions. The interaction parameter (χ) between the polymer and the solvent, and the average molecular weight between the crosslinks (Mc) were calculated from the swelling properties. © 1992 John Wiley & Sons, Inc.
DSC analysis of electron‐beam irradiated LARC–CPI
Authors: Mcherron Dale C. , Wilkes Garth L. 
Published: April 2003

AbstractThis work illustrates the response of LARC–CPI (a crystallizable polyimide) to electron‐beam radiation exposure under a nitrogen‐purged atmosphere. The response of LARC–CPI was monitored exclusively by differential scanning calorimetry (DSC), although some limited X‐ray scattering experiments were also employed. Three different types of LARC–CPI samples were irradiated: the “as‐received” semicrystalline films, highly amorphous films that were quenched from the melt, and recrystallized films. Comparison of the DSC behavior of these specimens elucidated the effects of electron‐beam irradiation on LARC–CPI as well as the influence of morphology (i.e., semicrystalline vs. amorphous states) on the radiation response of this polyimide. Results indicate that for the former two samples electron‐beam radiation does not significantly alter the crystalline phase present during irradiation. However, upon subsequent heating and cooling, the level of crystallinity decreases in all samples exposed to high doses (in excess of 100 Mrad). In addition, the crystallization temperature increases substantially with increasing radiation dosage, while a slight increase in the glass transition temperature is also observed. These results suggest that cross‐linking reactions may be occurring at sufficiently high doses, which would account for the observed melting and recrystallization behavior. However, due to the effects of thermal history on the crystallization behavior, there is some difficulty in definitively discerning all the specific effects of morphology on the radiation response of LARC–CPI.
Methods for predicting the quality of nylon 612 filament for use as a bristle material
Authors: Rawls H. Ralph , Casella Robert , Backus Verne , Dill Robert 
Published: April 2003

AbstractSplaying and curling of bristles is a very important performance characteristic of nylon toothbrushes. For this reason, analytical methods are needed that correlate fundamental physical–chemical properties with the eventural development of bristle splaying. Differential scanning calorimetry, thermogravimetric analysis, and wide‐angle X‐ray diffraction were each found to identify subtle differences in nylon 612 filament that had been subjected to varying processing conditions during manufacture. These differences were found to be related to water absorption and crystalline perfection and could be correlated with the characteristics of toothbrush wear. From the results, it was concluded that these three methods can be used for quality control and research purposes to predict and to study end‐use performance factors such as bristle splaying. © 1992 John Wiley & Sons, Inc.
High‐viscosity index lubricating oils from EPR destruction products
Authors: Seyidov N. M. , Kuliyev R. S. , Abasov A. I. , Gasanova R. Z. 
Published: April 2003

AbstractPolyolefinic oils obtained from olefin oligomerization or copolymerization involve the most common synthetic hydrocarbon oils. Research and experimental results concerning high viscosity index synthetic polyolefinic oils and viscosity index improvers' production by ethylene–propylene copolymer (EPR) and thermal destruction of EPRs noted for various molecular weight and composition resulted in high viscosity index polyolefinic oils and thickeners. The effect of structure, composition, and molecular weight on the destruction process has been discussed for various EPRs. The resulting polyolefinic oils and viscosity index improvers were studied. © 1992 John Wiley & Sons, Inc.
The effect of pressure and contaminants on slow crack growth in a butt fusion in a polyethylene gas pipe
Authors: Lu X. , Qian R. , Brown N. , Buczala G. 
Published: April 2003

AbstractThe effect of welding pressure and surface contaminants on butt fusion in a commercial polyethylene gas pipe was studied by measuring the slow crack growth resistance of the joint. Two weld pressures, 1.61 and 0.31 MPa, were used. The contaminants Vaseline, graphite, and Teflon were coated on the surface. It was found that the high pressure produced a weld with much better slow crack growth resistance than that by low pressure. At high weld pressure, Vaseline and graphite showed a negligible effect on weld quality. Teflon greatly reduced the lifetime, especially at low weld pressure. Test results showed that sufficient pressure was necessary to squeeze out the thin skin layer that occurs at the weld interface, along with any contaminants. The butt fusion joints were always much weaker than the reference pipe. This result was attributed to the difference in both cooling rate and molecular orientation between the pipe and weld. © 1992 John Wiley & Sons, Inc.