bluuebunny/crossref_metadata_2025_split huggingface dataset:
Morphology studies of the liquid‐induced crystallization of poly(ethylene terephthalate): Effects of polymer blending, nucleating agents, and molecular weight
Authors: Makarewicz P. J. , Wilkes G. L. 
Published: April 2003

AbstractThe morphology associated with the liquid‐induced crystallization of poly(ethylene terephthalate) (PET) blended either with poly(tetramethylene terephthalate) (PTMT), atactic polystyrene (APS), or polycarbonate of bisphenol A (PC) was studied, along with the effects of nucleating agents and polymer molecular weight on this type of crystallization in PET. It was found that melt‐mixed blends of PET and either PTMT or PC led to an apparent well‐mixed, two‐component material in which some copolymer formation may be in evidence judging from the material superstructure. Blending PET with APS appeared to produce distinctly phase‐separated materials in which PET could be crystallized and APS dissolved out of the structure as a result of treatment of the blend with certain types of liquid. The incorporation of nucleating agents into PET was shown to measurably influence the spherulitic character of the subsequently liquid‐induced crystallized polymer. Finally, it was determined that liquid‐induced crystallized PET samples with number‐average molecular weights of 18,000 and 30,000 had identical characteristic morphology and apparent crystallization kinetics.
Fine structure investigation of Sansevieria roxburghi fiber by small‐angle x‐ray methods
Authors: Ratho Sabita 
Published: April 2003

AbstractSmall‐angle x‐ray methods were used to evaluate macromolecular parameters such as specific inner surface of the dispersed phase; transversal lengths such as length of inhomogeneity and length of coherence; and the air fraction of the scattering particles in Sansevieria roxburghi; these parameters were found to be 12.76 × 10−6 Å−1, 549.9 Å, 15.21 Å, and 0.17%, respectively. A small‐angle Kratky camera was used for the experimental measurements, and the theories of Kratky and Kratky and Porod were utilized to evaluate these parameters. The sample under investigation is treated as a densely packed colloidal system belonging to general micelle systems.
Temperature dependence of impact fracture energies of short glass fiber–epoxy and unsaturated polyester composites
Authors: Miwa Minoru , Ohsawa Tadashi , Tsuji Naoki 
Published: April 2003

AbstractThe temperature dependence of the impact fracture energies of composites reinforced with random‐planar orientation of short fibers was studied theoretically and experimentally. The theoretical values of the impact fracture energy of these composites is described by the sum of the fracture energy of the matrix and the fibers and the energy necessary to pull out the fibers on the crack surface, taking into consideration the temperature dependence of the critical fiber length and the breaking probability of fibers. The impact fracture energies were studied experimentally for epoxy and unsaturated polyester resins reinforced with random‐planar orientation of short glass fibers. The theoretical values of the impact fracture energy were in good agreement with the experimental values. It was found that in any composite, the impact fracture energy of the fibers in a composite mainly contributes to the impact fracture energy of the composite at room temperature. At higher temperatures, fiber pull‐out energy is more significant.
The effect of chemical structure of derivatives of 1,1‐bis(4‐hydroxyphenyl)‐2,2‐propane on the antiplasticization of polycarbonate
Authors: Makaruk Leszek , Polańska Hanna , Mizerski Tadeusz 
Published: April 2003

AbstractThe antiplasticizing effect of ester derivatives of bisphenol A: 1,1‐bis(4‐hydroxyphenyl)‐2,2‐propane diacetate (DAPP), 1,1‐bis(4‐hydroxy‐3,5‐dichlorophenyl)‐2,2‐propane diacetate (DACPP), 1,1‐bis(4‐hydroxy‐3,5‐dibromophenyl)‐2,2‐propane diacetate (DABPP), 1,1‐bis(4‐hydroxy‐3,5‐dichlorophenyl)‐2,2‐propane dibenzoate (DBCPP), 1,1‐bis(4‐hydroxy‐3,5‐dichlorophenyl)‐2,2‐propane di‐2,4‐dichlorobenzoate (DCBCPP) on polycarbonate was investigated. Obtained results indicate that antiplasticizing abilities of these compounds depend on the number of polar groups in the molecule, as well as on the possibility of tight filling the free volume by the molecules in polymer–antiplasticizer system.
Reinforcement of siloxane elastomers by silica. Interactions between an oligomer of poly(dimethylsiloxane) and a fumed silica
Authors: Berrod G. , Vidal A. , Papirer E. , Donnet J. B. 
Published: April 2003

AbstractThe study of the adsorption of an organosiloxane onto a fumed silica was undertaken in order to improve our knowledge of the reinforcement of silicon rubbers by silica. IR and gas‐phase chromatography techniques were used to characterize the adsorption of octamethyltetracyclosiloxane. At room temperature, the occurrence of hydrogen bonding between the solute and the adsorbent was shown. The amount of material adsorbed according to this mechanism was shown to be strongly dependent on temperature. The heats of adsorption at various covering ratios were calculated from the isotherms measured at temperatures close to 150°C.
Transparent fluorocarbon‐based semi‐II IPN elastomers by high‐energy radiation methods
Authors: Lipko J. D. , George H. F. , Thomas D. A. , Hargest S. C. , Sperling L. H. 
Published: April 2003

AbstractSemi‐II interpenetrating polymer network fluorocarbon elastomers were prepared by the addition of small amounts of a multifunctional monomer to the linear fluorocarbon polymer, followed by radiation polymerization in situ. The linear fluorocarbon is physically bound up with crosslinked network II, producing a semi‐IPN of the second kind. Due to the high‐energy radiation attack on the fluorocarbon backbone, a significant amount of graft copolymer forms which improves compatibility and yields clear, transparent elastomers. High‐energy β and γ radiation produce very similar semi‐IPN elastomers. Low‐energy UV, which does not promote grafting, produces poorer quality elastomers which show significantly less optical clarity, much lower strength, and higher creep. High‐energy radiation also appears to destroy possible incipient crystallinity thought to be present in the linear fluorocarbon material.
The effect of transition metal stearates on the photodegradation of polyethylene
Authors: Osawa Zenjiro , Kurisu Norio , Nagashima Kosaku , Nakano Kosaku 
Published: April 2003

AbstractThe effect of a series of transition metal (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) stearates on the photodegradation of a high‐density polyethylene was examined mainly by changes in the carbonyl IR absorption of the sample films. Electron spin resonance (ESR) and luminescence spectra of the samples containing the copper stearate were measured. The photochemical reaction of the copper stearate was examined by IR and UV‐visible spectroscopies. The iron stearate was the most effective at an early stage of the photodegradation of the polymer, and vanadium and manganese stearates accelerated it, while the copper stearate retarded it. The other metal stearates showed no applicable effect on the photodegradation. The relative intensity of the ESR spectra of the photoirradiated samples and that of the emission spectra of the unirradiated samples at ca. 350 nm decreased with increasing concentration of the copper stearate. An absorption peak at 1580 cm−1 decayed, and a new peak at 1740 cm−1 appeared with photoirradiation of the copper stearate. Absorption peaks of the copper stearate at 252 and 665 nm decayed also rapidly with photoirradiation of the copper stearate in THF solution. The results suggest that one of the main retardative functions of the copper stearate in the photodegradation of polyethylene was an ultraviolet absorber.
Grafting starch xanthate with vinyl monomers and hydrogen peroxide in foam rubber production
Authors: Maher G. G. 
Published: April 2003

AbstractStarch xanthate with degrees of substitution (D.S.) ranging from 0.12 to 0.56 reacted with vinyl monomers (acrolein, acrylamide, acrylic acid, acrylonitrile, methyl acrylate, or styrene) and hydrogen peroxide to form aqueous gels of starch–polyvinyl monomer graft copolymer. The same reactions conducted in a rubber latex medium resulted in a self‐acidifying, self‐heating, and self‐foaming coagulation to give a foam rubber. Such products were formed from several synthetic latices (NBR, SBR, polyisoprene, and polychloroprene types) and natural rubber latex; noted for each were the effects of the D.S., of monomer and peroxide concentrations, and of starch:elastomer ratios. The dried foams were evaluated by standard strength tests. Foam rubber of acceptable extensibility and enhanced tensile strength (up to 110 psi) was obtained with 0.12–0.15 D.S. xanthate and with proper balance of vinyl monomer, peroxide, and starch:elastomer ratio. Resilience was fair to good, but compression set was rather poor compared to most foam rubbers of general use.
Flywheel‐type tensile impact tester with a new load cell for polymer sheet and film
Authors: Yokouchi Mitsuru , Kobayashi Yasuji 
Published: April 2003

AbstractA new load cell for flywheel‐type impact tensile testing was designed and fabricated for specimens of polymer sheet and film. The cell employs a piezoelectric ceramic oscillator (toric in shape) as a load sensor, which has a high natural frequency (1800 kHz) and high sensitivity (ca. 0.1 V/N without amplification). The time constant for the electric circuit was improved substantially by the introduction of a voltage follower using an operational amplifier with excellent performance (common mode voltage ±120 V and slew rate 100 V/μsec). The positioning of the load sensor and the shape of specimen clamps are important design features, especially the halved Morse‐type taper pins in the structure of the specimen clamps. Signals of impact, passing through the piezoelectric oscillator and the voltage follower, are recorded by a transient time converter. The converter is equipped with a memorization system, an automatic pretrigger circuit, and a facility for reproduction under a slow time base, thus eliminating the need for troublesome photographing. For performance testing of the impact tester, oriented poly(ethylene terephthalate) sheets were used and good results were obtained.
D2‐m‐carboranesiloxanes. VIII. Preparation and characterization of carboranesiloxane/polysulfone alternating block copolymer
Authors: Stewart D. D. , Peters E. N. , Beard C. D. , Moffitt R. B. , Kwiatkowski G. T. , Bohan J. J. , Hedaya E. 
Published: April 2003

AbstractA D2‐m‐dodecacarboranesiloxane containing alternating block copolymer \documentclass{article}\pagestyle{empty}\begin{document}$\rlap{--}[{\rm A}\hbox{---}{\rm B}\rlap{--}]_n$\end{document} was prepared by the reaction of a ureidosilane‐terminated polysulfone hard block with a carboranesilanol‐terminated carboranesiloxane oligomer. The resulting block copolymer exhibited thermoplastic elastomeric behavior. This unique polymer had excellent thermal stability up to 400°C.
Degradation of polymers subjected to radio‐frequency discharges in SF6
Authors: Gilbert Roland , Castonguay Jacques , Théorêt Antoine 
Published: April 2003

AbstractStudies were conducted on the degradation reaction of polyethylene, poly(tetrafluoroethylene), and an expoxy resin resulting from the action of a 13.56‐MHz radio‐frequency (rf) discharge in SF6. The curves showing the temperature variations of the samples during the experiment suggest that this degradation process occurs in two distinct stages: in the first, the heat released by the electric discharge causes the thermal degradation of the polymers, whereas in the second, the volatile degradation products react in the gas phase with the excited SF6. Analysis of the reaction products shows consistency with this two‐step degradation model. The main degradation products have been identified as C2H2, C2H4, SOF2, and CS2 in the case of polyethylene; as CF4, C2F4, and SOF2 in the case of poly(tetrafluorethylene); and finally as CO2 and SOF2 in the case of the epoxy resin. Furthermore, it is interesting to note the formation of polymers of the di(trifluoromethyl) polysulfane type, CF3‐Sn‐CF3, among the reaction products. The more volatile members, n = 2, 3, and 4, were identified by mass spectrometry, whereas the heavier members, identified by infrared spectrophotometry, often took the form of a whitish powder deposited on the walls of the reactor.
Reactivity of N‐methylolacrylamide in treatment of cotton under ultraviolet light
Authors: Reinhardt Robert M. , Arthur Jett C. 
Published: April 2003

AbstractN‐Methylolacrylamide (NMA) and cotton react readily under ultraviolet light when the treatment is carried out in an atmosphere of nitrogen. Reaction is almost completely inhibited by the oxygen in air. Polymerization inhibitors such as the methyl ether of hydroquinone (MEHQ) retard, but do not prevent, reaction. Longer radiation times, i.e., higher radiation doses, overcome the inhibitory effect of MEHQ. A photosensitizer such as biacetyl can increase the rate and efficiency of NMA‐cotton treatments, especially with short radiation times (low radiation doses). Relatively low ratios of photosensitizer to monomer produce such effects.
Cast and mold polymerization of organic glass by irradiation from fluid and soft gel prepolymers
Authors: Okubo Hiroshi , Yoshii Fumio , Nishiyama Sigeru , Yoshida Kenzo , Kaetsu Isao 
Published: April 2003

AbstractCasting and mold polymerization processes were investigated by means of γ‐irradiation of methyl methacrylate prepolymer systems containing some quantity of polyfunctional monomers. Some physical properties, such as supercooling tendency and temperature dependence of viscosity and relaxation time in fluid prepolymers, were measured and related to cast polymerization at low temperatures. It was found that free‐state casting with no frame or mold was possible using viscous states of prepolymer in the supercooled state. Furthermore, efficient mold polymerization using soft gel prepolymer was studied. That is, plastic soft gel prepolymer was prepared conveniently by irradiation of fluid prepolymer, then molded into spherical or nonspherical curved surface shapes, and curved by reirradiation. Polymerization and gelation behavior of soft gel prepolymer and penetration degree of prepolymer as a measure of plasticity of gel were studied in relation to prepolymer composition and irradiation condition.
The kinetics of hydrolytic polymerization of ϵ‐caprolactam
Authors: Tai Kazuo , Teranishi Hiroichi , Arai Yoshihiro , Tagawa Takashi 
Published: April 2003

AbstractA method to determine the concentration of ϵ‐aminocaproic acid (ACA) in poly‐ϵ‐caprolactam by high‐pressure liquid chromatography is established. The polymerizations for initial water concentrations of 0.42, 0.82, and 1.18 mol/kg and temperatures of 230, 240, 250, 260, 270, and 280°C were performed and concentration‐versus‐time curves were obtained for ACA, ϵ‐caprolactam (CL), and endgroups (EG). Each curve for ACA and EG has a maximum which increases monotonically in its value and shifts from right to left in position with increasing either the temperature or the initial water concentration. The reaction rates of CL, EG, and ACA were also evaluated numerically from the concentration data. The observed kinetic data were compared with those obtained by the numerical solution of the rate equations with Reimschuessel's kinetic constants. Good agreement is found in CL and EG concentrations but discrepancies in ACA concentration and rates are considerable, particularly in the early stage of the polymerization.
Permeabilität galvanisch beschichteter Polymerfolien. I. Methode zur Messung der Gaspermeabilität
Authors: Springer Jurgen , Brito Heide 
Published: April 2003

AbstractThe construction and function of an apparatus for the determination of gas permeability through metallized polymer films is described. The test gases N2, O2, and CO2 penetrate under pressure differences from 100 torr to 20 bar through galvanized ABS films (acrylonitrile–butadiene–styrene copolymer). The metallic layers consists of chemically deposited Ni and a galvanic deposited Cu having a thickness of 2–30 μm. The quantity of permeated gases is determined by gas chromatography. The lowest permeability coefficient obtained is 10−17 (cm3 cm/cm2 sec torr). Leak effects can be measured quantitatively. The permeability of gas mixtures (i.e., air) can also be investigated. The apparatus allows the determination of extremely low permeability rates as well as those for conventional polymer systems.
Dyeing of chemically modified cellulose. IV. Dyeing of oxidized celluloses with some reactive and direct dyes
Authors: Hebeish A. , Moursi A. Z. , Waly A. , El‐Rafie M. H. 
Published: April 2003

AbstractOxidation of cotton cellulose with potassium periodate, potassium dichromate‐sulfuric acid, and potassium dichromate‐oxalic acid results in creation of variable amounts of acidic and reducing groups along the cellulose molecule, being dependent upon the type of oxidizing agent used. Such groups were found to have a profound effect on the acceptability of cellulose for reactive and direct dyes. The rate and extent of dye uptake for the oxidized celluloses were significantly lower than those of the unoxidized cellulose. While presence of the acidic groups in cellulose molecules induces a negative environment thereby making approach of the dye anions to the cellulose difficult, presence of the reducing groups lowers the magnitude of cellulose reactivity as well as decreasing its adsorptive power. Further modification of the oxidized celluloses via either borohydride or chlorous acid treatment brought about modified celluloses the dyeability of which confirms the inhibiting effect of the acidic and reducing groups of those oxidized celluloses on the rate and extent of dyeing with reactive and direct dyes.
Degradation of polystyrene by gamma irradiation: Effect of air on the radiation‐induced changes in mechanical and molecular properties
Authors: Bowmer T. N. , Cowen L. K. , O'Donnell J. H. , Winzor D. J. 
Published: April 2003

AbstractIrradiation of 3 mm polystyrene sheet in air at 30°C with γ rays caused a rapid decrease in the tensile and flexural strengths and strains to fracture. These properties were decreased to 50% of their initial values after ca. 80 Mrads and to 25% after ca. 200 Mrads, beyond which dose the rate of change was relatively small. These results contrast with the negligible changes that are observed after 600 Mrads in vacuum. The effect of irradiation in air has been correlated with decreasing molecular weight at the surface, even though crosslinking predominated over the complete sample so that a gel point was reached at a dose slightly in excess of 100 Mrads. Scission and crosslinking yields, G(S) and G(X), were determined as a function of depth by gel permeation chromatography of layers removed progressively from the surface. G(S) decreased and G(X) increased with depth, in accord with the concepts of increased scission by reaction with oxygen and a diffusion effect. Unusual transverse cracking to a limited depth occurred during tensile measurements, a phenomenon that is attributed to the nonuniform molecular weight profile.
Effect of fillers on kinetics of epoxy cure
Authors: Dutta A. , Ryan M. E. 
Published: April 2003

AbstractThe effect of fillers on the reaction of liquid epoxy systems cured with m‐phenylenediamine has been studied within the temperature range 70–170°C using a Perkin–Elmer differential scanning calorimeter. Quantitative studies have been made with regard to the effect of filler on the kinetics of cure. Mathematical expressions have been devised to describe the curing reaction as a function of time, temperature, and filler content. These kinetic expressions were found to yield results which were in good agreement with the experimental data for the two fillers studied.
Thermodynamics of gas solubilities in molten polymers
Authors: Liu D. D. , Prausnitz J. M. 
Published: April 2003

AbstractPerturbed‐hard‐chain theory is extended to mixtures of polymers and volatile fluids, including supercritical gases. This extension is used to derive an expression for Henry's constant for a solute in a molten polymer. Theoretical calculations and data reduction are reported for a variety of solutes in polyethylene, polyisobutylene, and poly(dimethyl siloxane) in the temperature region 25–300°C. Calculated Henry's constants and their temperature dependence are generally in good agreement with the limited experimental data now available.
Mechanical and optical characterization of a photoviscoplastic material
Authors: Doyle James F. 
Published: April 2003

AbstractThe mechanical and optical properties of a polyester blend over a wide range of strain rates has been investigated for loading and unloading. The mechanical behavior, while being complex, was modeled adequately with a generalization of the four‐parameter viscoelastic model. The optical behavior has at least a three‐phenomenological coefficient dependence on the mechanical variables. Further, the stress birefringence is of opposite sign to that of the deformation.
A VSE equation of state for liquids. V. Poly(tetrafluoroethylene), 600–725 K
Authors: Doolittle Arthur K. 
Published: April 2003

AbstractOur volume–entropy–energy (VSE) equation of state for liquids, first proposed in 1973 for use with low molecular weight homogeneous liquids, is here applied for the first time to a high molecular weight liquid that is heterogeneous in molecular weight, namely, a molten polymer. Four thermo‐dynamic quantities, T, s, cp, and ε are calculated over the range of 600–725 K at ambient pressure and are compared with experimental values, with excellent results. The grand average of the standard percentage errors (S.P.E.) for the 24 points is 0.1100%.
Mechanics of the extension of cotton fibers. I. Experimental studies of the effect of convolutions
Authors: Hearle J. W. S. , Sparrow J. T. 
Published: April 2003

AbstractCotton fibers have structure at many levels. This paper is concerned with the effect of gross convolutions on tensile properties. Experiments with rubber tubes show that convolutions result from the collapse of a twisted hollow tube. In cotton, the convolutions will reverse at the helix reversals. Extension of cotton fibers and of nylon models shows that the initial easy extension is due to the untwisting of convolutions. If the amounts of S‐ and Z‐twist are different, the lesser part will become completely untwisted. Fibers stretched in water and then dried are without convolutions and are stiffer. Optical and SEM observations illustrate the behavior.
Dynamic mechanical behavior of chlorosubstituted derivatives of poly(ethyl methacrylate) and poly(ethyl acrylate)
Authors: Kolařík Jan 
Published: April 2003

AbstractA freely oscillating torsional pendulum was used in the investigation of the influence of trichloroethyl, tetrachloroethyl, trichloromethoxyethyl, and trichloroethoxyethyl side groups on the molecular mobility in the glassy state and on the glass transition temperature of poly(meth)acrylates. All the polymers under study, which may be used as fire retardants, exhibit a simple relaxation behavior. While the parameters of the low‐temperature and secondary relaxation process in the glassy state are not noticeably affected by the substituents used, the glass transition temperature Tg, increases with rising polarity and volume of side chains. The increase is larger in the series of polyacrylates, so that differences in the softening temperatures of polymethacrylates and polyacrylates having the same side chains decrease considerably with growing substitution.