bluuebunny/crossref_metadata_2025_split huggingface dataset:
Viscosity effect in polyolefin ternary blends and composites
Authors: Kim Byung Kyu , Kim Myun Soo , Kim Kook Joong 
Published: April 2003

AbstractTernary blends of PP (80) /rubber (EPM, EPDM) (10) / PE (10) and PP (80) / rubber (10) / CaCO3 (10) composites were prepared in a twin‐screw extruder. With polyethylene (PE) viscosity comparable to, or higher than that of rubber, the dispersed phase formed a reticulate structure with reduced size. On the contrary, when the viscosity of PE was significantly lower than that of rubber, the dispersed phase formed almost homogeneous morphology. With reticulate morphology, PE crystallinity content, hardness, modulus, and elongation at break of the ternary blend increased. In polypropylene (PP) / rubber / CaCO3 composites, better dispersion of CaCO3 in the PP matrix was obtained when the viscosity of rubber was significantly higher than that of matrix. With better dispersion, hardness and tensile properties were improved, but the impact strength more or less decreased. © 1993 John Wiley & Sons, Inc.
ABA triblock copolymers with two crystallizable blocks
Authors: Kuo Wen Faa , Tong S. N. , Pearce Eli M. , Kwei T. K. 
Published: April 2003

AbstractTriblock copolymers of the ABA type were synthesized in which the A block is poly(ethylene oxide) (PEO), having molecular weight of 1000 or 2000, and the B block is poly(dimethylsiloxane) (PDMS), having molecular weight of about 8000 or 10,000. When the triblock copolymer was cooled from the melt, the PEO block crystallized at around room temperature. Upon further cooling to liquid nitrogen temperature and reheating, the crystallization of the PDMS middle block took place at around −90°C. The melting temperatures and degrees of crystallinity of the PEO blocks in the copolymers were depressed from their respective pure state values. On the other hand, the melting points of the PDMS middle blocks in the copolymers were the same as the pure state values; furthermore, the degrees of crystallinity were unexpectedly much higher. © 1993 John Wiley & Sons, Inc.
Surface modification of polyethylene and magnetite powders by combination of fluidization and plasma polymerization
Authors: Inagaki N. , Tasaka S. , Ishii K. 
Published: April 2003

AbstractA new surface modification process of powders was attempted, using the combination of fluidization and plasma polymerization techniques. This study shows that the combination of the fluidization and plasma polymerization techniques is useful in the surface modification of powders.Polyethylene and magnetite powders were first fluidized, and then were modified in the fluidization state by the plasma polymers of tetrafluoroethylene (TFE). XPS spectra of the modified powders showed that the surfaces of the polyethylene and magnetite powders were coated with fluorine‐containing polymers, and that the polymers were mainly composed of CH, CF, and CF2 groups. The elemental composition (F/C atomic ratio) and the composition of the fluorinated carbons in the plasma polymers were dependent on the W/FM parameter, as well as the TFE concentration in the TFE/Ar mixture. It is emphasized that the W/FM parameter is a factor used to control the chemistry of the plasma polymerization reactions. The triboelectric charge of the magnetite powders, when modified by the plasma polymerization of the TFE/AR mixtures, was higher than the usnmodified by about two. The static electrification properties of the powders can changed by the plasma‐polymer‐coating. © 1993 John Wiley & Sons, Inc.
Humidity dependence of visible absorption spectrum of gelatin films containing cobalt chloride
Authors: Otsuki Soichi , Adachi Kimihiro 
Published: April 2003

AbstractGelatin films containing cobalt chloride were investigated to obtain information on the humidity dependence of optical absorbency in view of the coordinate state of cobalt ion and the polymer structure. The visible absorption spectra of the films exhibited that, with increasing relative humidity (RH), the absorption bands between about 550 and 750 nm decreased, accompained by sharpening of the 693 nm peak. Further, the decrease of cobalt chloride in gelatin resulted in decreased absorption intensity of the 693 and 668 nm peaks, more than the overall lowering in intensity. The infrared spectral data indicated that most of the carboxyl groups of gelatin are linked to the complex even in the strongly hydrated state. In addition, the water content of the films containing cobalt chloride is a little less below 42% RH, but is much greater above 62% RH than that of the original gelatin film. These results indicated that there are cross‐linked networks, composed of the hydrogen bonding and the coordination bond via the complex in the dry film; as water molecules are adsorbed by the film, they gradually destroy these bonds and swell the polymer. © 1993 John Wiley & Sons, Inc.
Extrusion processing of granular starch‐g‐poly(methyl acrylate): Effect of extrusion conditions on morphology and properties
Authors: Trimnell D. , Swanson C. L. , Shogren R. L. , Fanta G. F. 
Published: April 2003

AbstractStarch‐g‐poly(methyl acrylate) copolymers (S‐g‐PMA) containing 10, 30, 46, and 58% PMA, by weight, were prepared by ceric ammonium nitrate‐initiated polymerization of methyl acrylate onto granular cornstarch. Graft copolymers were extrusion‐processed through a strand die with water contents of 10 and 30% (based on starch) and at temperatures of 140 and 180°C, and the resulting strands were then pelletized. Properties of ribbons prepared from extrusion‐processed S‐g‐PMA depended on the combined effects of processing temperature, PMA level in the graft copolymer, and water content during extrusion. Ribbon formation was poor at the lowest PMA level of 10%, and extruded ribbons did not have sufficient continuity for tensile testing. Ribbons with smooth surfaces were obtained with 10% water in the polymer, whereas a water content of 30% produced extrudates that were rough and pebbly. When processed with 10% water, graft copolymers containing 46 and 58% PMA exhibited the highest values for both ultimate tensile strength (UTS) and % elongation at break (%E) when the extrusion was performed at 180°C. UTS was reduced and %E was increased when the water content during processing was increased to 30%. At the highest grafting level (58%), discrete granules of S‐g‐PMA were still apparent in scanning electron micrographs of extruded ribbons. More granule disruption occurred when the PMA level was reduced to 46%, and virtually none of the original granule structure remained after extrusion with 30% water. The effect of water content during processing was especially apparent at the grafting level of 30%, and extrudate properties were consistent with the formation of starch as the continuous phase under high moisture conditions. The behavior of S‐g‐PMA granules during extrusion can be explained by cross‐linking within the starch matrix during the graft polymerization reaction. DSC data were consistent with this theory. © 1993 John Wiley & Sons, Inc.This article is a US Government Work and, as such, is in the public domain in the United States of America.
Polyamides containing olefinic bonds
Authors: Mikroyannidis John A. 
Published: April 2003

AbstractThe reaction of 2,5‐dimethylpiperazine with a double molar amount of maleic anhydride afforded a new unsaturated dicarboxylic acid that was characterized by IR and 1H‐NMR spectroscopy. It was condensed with various aromatic diamines by the phosphorylation method to yield polyamides bearing olefinic bonds. They were readily soluble in polar aprotic solvents and certain acids. The DTA traces of polyamides showed exotherms above 250°C attributable to their cross‐linking through the olefinic bonds and a partial thermal degradation. Evidence for the cross‐linking of polyamides attained during their heat‐curing was obtained from the IR spectra of the uncured and cured samples. Thermal stabilities of cured (at 300°C for 15 h) polyamides were evaluated by TGA and isothermal gravimetric analysis. They were stable up to 321–336°C in N2 or air and afforded an anserobic char yield of 61–71% at 800°C. © 1993 John Wiley & Sons, Inc.
A study of the interaction of mechanically generated polypropylene radicals with phenolic antioxidant in the presence of oxygen by EPR spectroscopy
Authors: Hloušková Zuzana , Lustoň Jozef , Szöcs František 
Published: April 2003

AbstractIsotactic polypropylene (iPP) was mechanically degraded in the absence and presence of a phenolic antioxidant at liquid nitrogen temperature in the presence of oxygen. The interaction of the primarily formed iPP macroradicals with oxygen and phenol was studied by EPR spectroscopy in the temperature region between 77 and 303 K at antioxidant concentrations of 0.1, 0.5, and 3.0 wt%. It was found that iPP macroradicals react at low temperature with oxygen, yielding peroxy radicals, and with antioxidant, with a simultaneous formation of phenoxy radicals. The development and decay of all kinds of radicals was studied. The rate constants for peroxy radical decay were determined and the apparent activation energies for the regions of slow and fast decay were calculated. © 1993 John Wiley & Sons, Inc.
Surface microstructure of MMA‐HEMA polymer membranes
Authors: DomíNguez J. M. , Palacios J. , Espinosa G. , Schifter I. 
Published: April 2003

AbstractA series of MMA‐HEMA polymer (hydroxyethyl methacrylate) membranes were prepared using several copolymer precursor mixtures and were characterized by transmission and scanning electron microscopy. The correlation between the preparation methods and the microstructure of the porous layers was sought. The cryofracture procedures also were investigated in order to observe the polymer membranes in the electron microscope. It was found that the porosity of the intermediate transport layer depends on the molecular weight composition and the MMA/HEMA copolymer ratio; the presence of dimethylformamide (DMF) also has a marked influence on the microtextural properties of the transport layer. The main features of the selective layer surface are the very fine roughness, with pits and pores in the 1‐5 nm range, and the chainlike protuberances at the nanometer scale. The cryogenic fracture methods proved adequate for observation of the new MMA‐HEMA‐type membranes without artifacts. © 1993 John Wiley & Sons, Inc.
Hydrophilic surface modification of polypropylene films by CCl4 plasma
Authors: Inagaki N. , Tasaka S. , Imai M. 
Published: April 2003

AbstractThe CCl4 plasma treatment of polypropylene films was investigated from the viewpoint of hydrophilic surface modification using a contact‐angle meter, ATR FTIR spectroscopy, and angular XPS. Hydrophilicity and chemical composition of the CCl4 plasma treatment was effective in hydrophilic modification. The advancing contact angle of water for polypropylene films was decreased from 99° to 81‐7° by the CCl4 plasma treatment, and the surface energy increased from 27.2 to 38.9‐67.7 mJ/m2 when the discharge current varied from 50 to 150 mA. The CCl4 plasma initiated chlorination, oxidation, and aluminum sputtering reactions. The chlorination of polypropylene films was favorable in a mild CCl4 plasma operated at discharge current of 50 mA. The oxidation and aluminum sputtering reactions were predominant over the chlorination in strong CCl4 plasmas operated at discharge currents of more than 75 mA. The chlorination initiated by the mild CCl4 plasma was restricted near the film surface within 36 Å deep. The regions modified with the strong CCl4 plasma reached inner layers of 36‐49 Å deep. Hydrophilicity caused by the CCl4 plasma treatment may be due not only to chlorine functionalities but also to oxygen and aluminum functionalities. © 1993 John Wiley & Sons, Inc.
Development of polyurethane engineering thermoplastics. II. Structure and properties
Authors: Frontini Patrica M. , Rink Marta , Pavan Andrea 
Published: April 2003

AbstractRigid, tough thermoplastic polyurethanes were synthesized by a two–step technique. These materials presented a complex structure consisting of a continuous, rigid, amorphous, or semicrystalline matrix with a dispersed soft phase. The influence of soft–segment content upon rigidity modulus, heat–distortion temperature, and fracture behavior has been deter‐mined on model amorphous polyurethanes. The influence of crystallinity upon final prop‐erties has been studied on two materials: a preparation of ours and a commercial product. Various degrees of crystallinity have been induced in the samples by annealing. Phase structure was characterized by differential scanning calorimetry and wide–angle X–ray scat‐tering. Some of the polyurethane samples assayed in this paper exhibited similar properties to those reported in respect of more conventional engineering thermoplastics, such as ABS or nylon. © 1993 John Wiley & Sons, Inc.
Effect of melt‐state curing on the viscoelastic properties of poly(phenylene sulfide)
Authors: Scobbo James J. 
Published: April 2003

AbstractLow molecular weight, low viscosity poly(phenylene sulfide) (PPS) has been cured in the melt state to examine effects of curing time and temperature on the melt‐state dynamic viscoelastic behaviour. It was found that the Newtonian behaviour of the uncured material could largely be retained if melt cure temperatures are properly controlled. This result is in contrast to solid‐state curing, where the Newtonian nature of the resin is reduced, pre‐sumably due to increased branching and cross‐linking as molecular weight builds. The current result indicates that melt‐state curing may provide a high molecular weight PPS resin with a predominantly linear molecular architecture. © 1993 John Wiley & Sons, Inc.
Miscibility, crystallization, and melting of the blends of a ferroelectric VDF/TrFE copolymer and PMMA
Authors: Kim Kap Jin , Kim Gwan Bum , Han Seung Hwa 
Published: April 2003

AbstractFactor analysis by IR and melting‐point depression indicated miscibility between poly (vinylidene fluoride/trifluoroethylene) [P (VDF/TrFE)] and poly (methyl methacrylate) (PMMA) in the melt state. χ12 was found to be −0.229 at 160°C. PMMA reduced the rate of crystallization of P (VDF/TrFE) drastically by increasing both ΔG* and ΔGη. The double melting of the blend crystallized nonisothermally originated from the presence of two morphologically different crystals in the paraelectric crystalline state. © 1993 John Wiley & Sons, Inc.
Improved interaction effected by maleic anhydride‐grafted polypropylene in PRP triblock polymer–EVA blend
Authors: Hudec Ivan , Sain M. M. , Šúňová Véra 
Published: April 2003

AbstractThe role of anhydride‐grafted polypropylene in the ethylene–propylene triblock polymer and ethylene–vinyl acetate copolymer blend has been studied. Maleic anhydride grafted onto polypropylene interacts with polymer components in the blend and also improves the dispersion of the rubber phase in the plastic matrix. Improved interaction is reflected in the ultimate properties of the blend. Blends with good impact resistance and low‐temperature brittleness may be obtained by optimizing the modifier concentration. Composition with good low‐temperature brittleness is achieved by lowering the glass transition temperature of the plastic phase by adding a low concentration of modifier. Impact strength of the studied blend does not depend only on the reactive maleic anhydride content but also on the type of modifier. Generally, an increase in interfacial surface area improves impact strength. © 1993 John Wiley & Sons, Inc.
Structure of toluene sulfonamide formal resins: Molecular models from mechanistic schemes and analytical results
Authors: Chiva V. , Lecacheur M. , Faure R. , Gallo R. , Wimmer E. 
Published: April 2003

AbstractToluene Sulfonamide Formaldehyde Resins (TSFR), having elemental analysis close to (C8H9NSO2)n, are shown by GPC to exist as a mixture of a few (5 to 6) oligomers, having masses between 400 and 1900 g. A complete scheme of all the possible intermediates involved in their preparation is derived from the results of synthesis and from mechanistic steps; this allows one to propose the structure of oligomers having end groups OH and NH. IR, 1H NMR, and 13C NMR data on oligomers, compared to those of authentic samples specially designed and prepared, agree with the structures proposed. These results are helpful in designing modified or new resins to be used in nail lacquers. © 1993 John Wiley & Sons, Inc.
Flow behavior of symmetrical P (S‐b‐MMA) block copolymers: Rheological problems arising from shear modified morphology
Authors: Braun H. , Gleinser W. , Cantow H.‐J. 
Published: April 2003

AbstractIn this article, symmetrical, narrow distribution P (S‐b‐MMA) block copolymers are characterized rheologically, using a dynamic spectrometer and a stress rheometer. The shear induced morphology changes are investigated by off‐line electron microscopy and SAXS. We tried to correlate the results of dynamics and long‐time creep experiments with morphological and rheological features. Summarizing, one can point out that the examined block copolymers reveal the well‐known low frequency behavior of phase separated blends. Additionally, we observed a significant shear influence on the morphology, i.e. a shear induced structuring and alignment of lamellae. This considerable change in morphology is also reflected by the characteristic rheological properties (retardation time, yield stress). Therefore, problems concerning the validity range of linear viscoelastic behavior arise, which are discussed in brief. © 1993 John Wiley & Sons, Inc.
Preparation of polyimide composite membrane by chemical vapor deposition and polymerization technique (CVDP)
Authors: Yanagishita H. , Nakane T. , Nozoye H. , Yoshitome H. 
Published: April 2003

AbstractA dry process of chemical vapor deposition and polymerization (CVDP) was employed to prepare a polyimide composite membrane for water–ethanol separation, using an apparatus newly developed for this investigation. The characteristics of the apparatus were studied by depositing pyromellitic dianhydride (PMDA) and 4,4′‐diaminodiphenyl ether (P,P′‐oxydianiline, ODA) in a vacuum of 10−6 Torr. Deposited layers were converted to a thin polyimide film by heating at 200°C for 3 h in a vacuum. The composite membranes were prepared by forming a polyimide layer of 0.2 μm thickness on the surface of asymmetric supporting membranes made by the phase‐inversion process. The polyimide composite membranes prepared under the best conditions exhibited a separation factor α (H2O/EtOH) of over 140 for 95 vol% aqueous ethanol solution with flux of 0.1 kg/m2 h at 25°C in pervaporation mode. Also, it was demonstrated that this new technique of chemical vapor deposition and polymerization (CVDP) was very useful for the preparation of a solvent‐resistant composite membrane in a completely dry process. © 1993 John Wiley & Sons, Inc.
Changes in physical properties of methacrylonitrile (MAN)‐grafted silk fibers
Authors: Tsukada Masuhiro , Freddi Giuliano , Shiozaki Hideki , Pusch Noriko 
Published: April 2003

AbstractChanges in physical properties of silk fibers, grafted with methacrylonitrile (MAN), were investigated as a function of the weight gain. The weight gain increased steadily during the first 60 min of reaction and gradually attained an equilibrium value (60%) after about 4 h. The initial tensile resistance of silk fibers decreased by MAN grafting. The crystalline structure of silk fibers remained unchanged, regardless of MAN grafting, however. a minor and broad peak appeared in the X‐ray diffraction curves of MAN‐grafted silk fibers with a weight gain of 60%, corresponding to the unoriented MAN polymer attached inside the fibers. Molecular orientation of silk fibroin chains in the crystalline regions, evaluated from X‐ray diffraction curves, did not change significantly, while both birefringence and isotropic refractive index decreased as the weight gain increased, implying that MAN polymer attached preferentially to the amorphous and not to the crystalline regions. Dynamic vis‐coelastic measurements showed that the position at which the E′ value began to decrease shifted to a lower temperature as the weight gain increased. These findings suggest that the thermal movement of silk fibroin molecules was accelerated by the presence of the poly‐MAN chains attached to the amorphous regions of silk fibroin fibers. © 1993 John Wiley & Sons, Inc.
Strain‐Coupling effects in extensional flows
Authors: Vrentas J. S. , Vrentas C. M. 
Published: April 2003

AbstractA recently developed strain‐coupling constitutive equation for nonlinear viscoelasticity is used to analyze extensional flows. Comparisons are presented between the predictions of the theory and experiment for equibiaxial‐ and uniaxial‐step strain‐stress relaxation experiments. © 1993 John Wiley & Sons, Inc.
Thermal degradation of polydigolphosphate
Authors: Basu Sudhapada , Chatterjee Nandini , Maiti Mrinal M. 
Published: April 2003

AbstractA new inherently cross‐linked polymer, polydigolphosphate, has been synthesized. The polymer has high affinity for moisture and a tendency to retain sodium chloride, which is produced as a coproduct in the synthesis of the polymer. The purity and, hence, the structural identity of the polymer have been established by combined DTA‐TG analyses in an inert atmosphere. Thermal degradation of the polymer has been quantitatively correlated on the basis of a proposed mechanism. The mechanism may serve as a representative one for the degradation of similar polyphosphates of poly(ethylene glycol). © 1993 John Wiley & Sons, Inc.
Isothermal curing of an uncatalyzed dicyanate ester monomer: Kinetics and modeling
Authors: Georjon Olivier , Galy Jocelyne , Pascault Jean‐Pierre 
Published: April 2003

AbstractThe isothermal cure of a dicyanate ester monomer has been studied under different atmospheres (air and argon) without any catalyst, by following the evolutions of both glass transition temperature and conversion. Independently of both atmosphere and temperature of cure, there is a unique one‐to‐one relationship between these two parameters, correctly described by a restated DiBenedetto's equation. The chemical kinetics are satisfactorily modeled with two competing reactions schemes, which are second‐order and second‐order autocatalyzed, the latter displaying more relative importance under air‐curing conditions. Whatever the cure temperature may be, gelation occurs around 0.60 conversion under air, whereas the theoretical xgel = 0.50 is experimentally observed under argon. The time–temperature‐transformation diagrams have been established. © 1993 John Wiley & Sons, Inc.