bluuebunny/crossref_metadata_2025_split huggingface dataset:
Annealing of plasticized PVC. Dilatometric and DSC observations
Authors: Garrett T. B. , Goldfarb L. 
Published: April 2003

AbstractIsothermal dilatometric measurements on quenched, plasticized PVC have been made at a series of temperatures, and a mathematical expression has been obtained to described the specific volume as a function of time. The results of these measurements, along with those obtained using differential scanning colorimetry (DSC) for the change in enthalpy accompanying annealing, clearly show a change in the character of the annealing process with rising temperature; but the underlying molecular kinetic mechanism apparently remains unchanged.
Load and temperature dependence of frictional force and frictional electrification in friction between polymer films obtained by simultaneous measurements
Authors: Ohara Keiji 
Published: April 2003

AbstractSimultaneous measurements of frictional force (F) and frictional electrification charge density (σ) were carried out for PS/Ny, PC/PET, and PS/PC polymer film sample systems in the temperature range of 10° to 100°C under various loads (W). Load dependence of F and σ were expressed by F = αWn and σ = βWm. Values of n and m changed with the number of rubbings and temperature. Rate of decrease in n became larger at about 90°C for all sample system. For PS/Ny systems, the values of m and n changed in a similar manner. This behavior was explained in terms of variations in true contact area. Values of F and σ were at maxima and/or began to increase at the temperatures corresponding to the glass transition temperature of the α‐peak temperature in viscoelastic polymers. The maxima of F and σ may appear when the frequency of thermal motion of molecules taking part in the adhesion and separation process coincides with the frequency of mechanical motion of adhesion and separation (friction) between two surfaces, namely, when the true contact area becomes maximum.
Distribution of carbon black in SBR
Authors: Oono Ryo 
Published: April 2003

AbstractThe distribution of HAF carbon black in SBR was studied with the electron microscope and Fraunhofer diffraction. The interparticle distance between black aggregates is 8000 Å at 20 phr and 7000 Å at 40 phr, but above 60 phr it spreads broadly in the vicinity of 4000 Å. The size of black aggregates at 20 phr extends from 300 Å to 3000 Å, and the average diameter is 1200 Å. At 40 phr and 60 phr, black trends to aggregate more than at 20 phr and the average diameter is about 1500–1600 Å; the maximum diameter exceeds 5000 Å. In a black aggregate, there are about 40 spherical particles independently of filler concentration. From the relation between the size and interparticle distance, the connection of black aggregates initiates at 40 phr level and affects the physical properties of filled rubber.
Vulcanization of butyl rubber by p‐quinone dioxime
Authors: Gan L. M. , Soh G. B. , Ong K. L. 
Published: April 2003

AbstractThe vulcanization of butyl rubber by p‐quinone dioxime oxidized by red lead and tetrachloroquinone was investigated. The maximum physical effective crosslinking density of the vulcanizates appeared to be when p‐quinone dioxime and the oxidizing agent were equimolar. The formation of one physical effective crosslink required one molecule of p‐quinone dioxime. Chemical reactions are suggested for the vulcanization steps.
Properties of elastomers crosslinked by bisglycidyl ether of 2,2‐bis(p‐hydroxyphenyl)‐1,1,1‐trichloroethane
Authors: Brzozowski Zbigniew K. , Gajewski Mieczysław , Brzeziński Zdzisław 
Published: April 2003

AbstractChlorobisphenolic epoxy resins in crystalline form, e.g., bisglycidyl ether of 2,2‐bis(p‐hydroxyphenyl)‐1,1,1‐trichloroethane (BGECBP) and the system sulfur–N‐cyclohexyl‐2‐benzothiazolesulfonamide were used as crosslinking agents for vulcanization of butadiene–styrene and butadiene–acrylonitrile rubber. The density of crosslinking was determined by the equilibrium swelling method and on the basis of the Mooney‐Rivlin equation which gives the relation between stress and elongation. The dynamic properties, namely, G′ and G″ and mechanical loss factor δ, were determined. On the basis of these results, mechanisms for the crosslinking reaction were advanced, the activation energy was determined, and comparisons between crosslinking rates by different systems were made. It was found that vulcanizates crosslinked by BGECBP possess higher heat aging resistance and lower glass transition temperatures in comparison with those crosslinked by means of sulfur in the presence of N‐cyclohexyl‐2‐benzothiazolesulfonamide.
Bromostyrene‐crosslinked polyesters. III. Electrical properties
Authors: Konieczny N. , Marom G. , Weinberg A. 
Published: April 2003

AbstractVolume resistivity, dielectric strength, dielectric constant, and loss tangent of unsaturated polyester resins and their GRP were studied as a function of the bromine content of the resin. The bromine was introduced by using bromostyrene as the crosslinking monomer. Bromine content was established by partial or total replacement of the styrene. Also, the effects of short and long water‐boil treatments on these properties were investigated. The electrical and dielectrical properties were shown to be independent of the bromine content of the resin.
Application of rayleigh spectroscopy to the study of emulsion and dispersion polymerization and polymers
Authors: Killgoar Paul C. , Dickie Ray A. 
Published: April 2003

AbstractApplication of Rayleigh spectroscopy for characterization of particle size in nonaqueous dispersion and water‐based emulsion paint resins is described. The technique allows a straightforward and rapid estimation of particle size; the measurement does not require exact determination of scatterer concentration. For monodisperse samples, unambiguous results are obtained for particles at least up to 50 μm in diameter; for polydisperse samples, an average size heavily weighted by large particles is obtained. Typical experimental results on monodisperse and polydisperse water‐based latexes and on polydisperse nonaqueous dispersion resins are described. In the latter case, comparison of electron micrograph and light scattering size determinations indicates that the light scattering experiment yields approximately a z‐average radius. Observations on particle formation and growth during polymerization are also described.
Some limitations on the detection of high elongational stress effects in dilute polymer solutions
Authors: Ting R. Y. , Hunston D. L. 
Published: April 2003

AbstractThe elongational flow behavior of dilute polymer solutions is of great current interest because it has been suggested that elongational viscosity effects may be involved in a number of phenomena such as turbulent drag reduction and flow cavitation suppression. Unfortunately, recent experiments, in trying to investigate elongational effects, have produced widely varying results. In this paper, an attempt is made to analyze one of the factors that contribute to this diversity. By using a generalized convected Maxwell model, it is shown that in a transient elongational flow, both stretching rate and flow time must reach the proper values before high stress levels can be observed. This is true for both accelerating flows such as through a cone or wedge and decelerating flows such as in a free jet. Since most previous experiments have not considered flow time, consistent results cannot be expected. Consequently, the proper control of all flow conditions is an essential requirement when trying to observe high stress levels. The results presented here provide valuable guidelines in this regard.
Ultrasonic studies of polycarbonate, polysulfone, and polyether sulfone
Authors: Phillips D. W. , North A. M. , Pethrick R. A. 
Published: April 2003

AbstractUltrasonic attenuation and velocity measurements are reported for samples of polycarbonate, polyether sulfone, and polysulfone over a temperature range from 10° to 80°C and over a frequency range from 5 to 35 MHz. Observed relaxations are ascribed to short‐range motions of the polymer backbone—here designated the α process. The amplitude of the absorption initially decreased with increasing draw ratio, but after two years returned to the values characteristic of undrawn samples. The longitudinal wave velocity increased with draw ratio in a manner consistent with the creation of molecular order and remained constant over two years. Differences in the attenuation properties between the three polymers studies are discussed in terms of the chemical structure and the macroscopic morphology of the samples.
A new method for correcting axial dispersion in GPC
Authors: Marais L. , Gallot Z. , Benoît H. 
Published: April 2003

AbstractIn this paper, a new method for correcting GPC results in order to take into account the axial dispersion of a given set of columns is proposed. The idea is to evaluate the different average molecular weights and the polydispersity for a given elution volume. In order to do so, one needs only to know the efficiency of the set of columns and the different derivatives at a given point of the chromatogram. Some possible applications of this method are reviewed mainly for the characterization of polydispersity and for the determination of the viscosity law if one uses the universal calibration.
A new process of decrystallization and partial acetylation of cellulosic materials
Authors: Kulshreshtha A. K. , Dweltz N. E. 
Published: April 2003

AbstractA new process of decrystallization of cellulosic materials8 is described. The process involves the preparation of alkali‐cellulose and an interaction between alkali‐cellulose and acetic anhydride. The decrystallized products thus obtained are partially acetylated and are designated as SPA (S for swollen, PA for partially acetylated) products. The effect of varying the alkali concentration on the structure and mechanical properties of SPA products is described. Maximum decrystallization is obtained when the swelling is carried out in alkali of intracrystalline swelling strength, prior to treatment with acetic anhydride. Acetylation is instrumental in retaining the highly decrystallized state. The structure of SPA cotton was characterized using chemical analyses, infrared spectroscopy, and x‐ray diffraction.
Basic principles of thermal degradation and thermal stabilization of poly(vinyl chloride). Mathematical model of the action of PVC thermal stabilizers
Authors: Prochaska Krzysztof , Wypych Jerzy 
Published: April 2003

AbstractA model of the action of chemically homogeneous thermal stabilizers of poly(vinyl chloride) is shown. Based on the described computer program and experimental data, the proposed model is confirmed and rate constants of the reaction of stabilizers with HCI and the effect of the products of this reaction on the kinetics of PVC degradation are calculated.
Quinoxaline/phenylquinoxaline copolymers
Authors: Hergenrother P. M. 
Published: April 2003

AbstractThe thermal crosslinkability of the quinoxaline moiety incorporated within poly(phenylquinoxalines) was demonstrated by differential scanning calorimetry (DSC), torsional braid analysis (TBA), and high‐temperature adhesive evaluation. Several homopolymers, random copolymers, and polymer blends were prepared and evaluated. A new bis(1,2‐dicarbonyl) monomer, 4‐(4‐phenylglyoxalylphenoxy)phenylglyoxal hydrate, was prepared and reacted with 3,3′, 4,4′‐tetraaminobiphenyl to provide a polymer where a phenyl group was located on alternating quinoxaline rings. The apparent Tg of this polymer was initially 280°C and increased to 360°C after exposure to 400°C for 0.5 hr in air.
Isotactic polystyrene characterization by gel permeation chromatography in tetrahydrofuran
Authors: Guenet J. M. , Gallot Z. , Picot C. , Benoit H. 
Published: April 2003

AbstractIsotactic polystyrene fractions were characterized by gel permeation chromatography (GPC) in tetrahydrofuran (THF) at 25°C. From the universal calibration method, a viscosity law has been established allowing determination of the correspondence between the molecular weight GPC calibration laws for APS and IPS. The validity of characterization of IPS by this method was confirmed with light scattering and osmometry.
Electron spin resonance studies on photodegradable polymers
Authors: Windle John J. , Freedman Bernard 
Published: April 2003

AbstractFilms of polyethylene (PE), polypropylene (PP), and polystyrene (PS) containing 1% of selected halogen compounds and films without additives were UV irradiated (253.7 nm) at 77°K and their electron spin resonance (ESR) spectra compared. In each case, the spectra were characteristic of the polymer, and the presence of the additive mainly enhanced the radical yield. No signal was observed for the additives alone after irradiation, suggesting that when incorporated into the polymer, they serve as photosensitizers rather than as primary sources of free radicals in promoting photo‐chemical degradation.
Photo‐oxidation and photoprotection of the surface resin of a glass fiber–epoxy composite
Authors: George G. A. , Sacher R. E. , Sprouse J. F. 
Published: April 2003

AbstractThe rapid photo‐oxidation of the surface epoxy resin of a commercial seven‐ply laminate (Scotchply 1009‐26) is due principally to the epoxy novolac resin component. The photo‐oxidation rate of this resin is eight times that of the other component, a bisphenol A epoxy resin. This rate depends on the conditions of cure, and photo‐initiation occurs in part through aromatic carbonyl groups formed by oxidation of the methylene linkages of the novolac at the cure temperature (160–180°C). Inhibition of this thermal oxidation by vacuum cure or a chain‐terminating antioxidant increases the photostability. Photoprotection of thin resin sections by the UV stabilizer 2‐hydroxy‐4‐isooctoxybenzophenone and an epoxidized analog is assessed.
Environmental stress cracking of polyethylene
Authors: Singleton C. J. , Roche E. , Geil P. H. 
Published: April 2003

AbstractDeformation of polyethylene in environmental stress cracking (ESC) agents results in changes in both the mechanism of deformation and structure of the resulting drawn material. Stress‐cracked failure surfaces are highly fibrillar, the fibrils having less elastic recovery than those in samples drawn in air. In thin films drawn in ESC agents, small blocks of the lamellae remain undrawn and attached to the fibrils drawn across micronecks. The ESC agents are suggested to weaken the cohesion between the fibrils in samples drawn beyond yield as well as the cohesion between mosaic blocks or similar structural elements in the original lamellae as they are being reoriented to form the fibrils. The stress is thus supported by a number of independent, nonuniform fibrils rather than a coherent structure; the weakest of these fibrils fail in turn as the crack propagates through the sample.
The effluent analysis of several pyrrone and polyimide precursors during cyclization
Authors: Sykes George F. , Young Philip R. 
Published: April 2003

AbstractA study was conducted to determine the degree of cyclization occuring in a series of four pyrrone and two polyimide prepolymers. These materials were heated from 25° to 400°C at 2°C/min in a helium atmosphere, and the effluent was sampled at regular intervals by a gas chromatograph/mass spectrometer technique. Quantitative analysis of this effluent indicated that the pyrrone polymers were less than 80% converted under these conditions while the polyimides were essentially fully converted. Significant amounts of carbon dioxide were found to be eliminated as the pyrrone polymers cured. This evolution was attributed to the loss of carbon dioxide from intermediate stages during cure and, in some cases, to the decarboxylation of unreacted groups. Support data obtained on model compounds are also presented.
On the form of the strain energy function for a family of SBR materials
Authors: Arenz R. J. 
Published: April 2003

AbstractA strain energy function of the Valanis‐Landel type, W = w(λ1) + w(λ2) + w(λ3), is shown to be applicable to styrene–butadiene rubber (SBR) materials having varying crosslink densities νe. A previously obtained functional form of the strain energy derivative w′(λ), normalized by dividing by νe, is confirmed by one of the validity check plots in which a single curve represents the whole body of large‐deformation test results for all degrees of biaxiality and crosslink density.
Localized radiation grafting of flame retardants to poly(ethylene terephthalate). I. Bromine‐containing monomers
Authors: Liepins R. , Surles J. R. , Morosoff N. , Stannett V. T. 
Published: April 2003

AbstractVinyl bromide was used as a model for bromine‐containing flame retardants in developing methodology for localizing flame retardants either on the surface of the filament, uniformly throughout it, or predominantly at the core. SEM–x‐ray microprobe techniques were used in the verification of the location of the flame retardant in the filament. The flame retardance efficiency of PVBr was then correlated with its location in the filament. Grafting other bromine‐containing flame retardants showed a wide range of efficiencies which depended not only upon the location of the grafting within the filament but also upon the structure of the compound. For the various bromine homopolymer grafts, the apparent thermal stability of the graft and its flame retardance efficiency may be simply related to the alpha aliphatic hydrogen‐to‐bromine ratio. The lower this ratio is, the higher the efficiency. VBr copolymers and terpolymers showed wider variation in flame retardance efficiencies. This is attributed to large variations in melt viscosity of the different grafted materials. The grafts showed only small changes in their melting points and minimal changes in tenacity and stiffness. However, grafting induced large increases in the elongation.
Entanglement networks of 1,2‐polybutadiene crosslinked in states of strain. IV. States of ease and stress–strain behavior
Authors: Carpenter Rick L. , Kramer Ole , Ferry John D. 
Published: April 2003

AbstractLinear 1,2‐polybutadiene, glass transition temperature (Tg) −18°C, is crosslinked at −10°C, to −20°C by γ irradiation while strained in simple extension, with extension, ratios (λ0) from 1.2 to 2.7. After release, the sample retracts to a state of ease (λs) at room temperature. From equilibrium stress–strain measurements up to a stretch ratio relative to the state of ease (Λ) of 1.2, together with λ0 and λs, the concentration of network strands terminated by trapped entanglements (νN) is calculated. For this purpose, a three‐constant Mooney–Rivlin formulation is used, in which the entanglement network is described by Mooney–Rivlin coefficients C1N and C2N, whereas the crosslink networks is described by the coefficient C1x only. The ratio ψN = C2N/(C1N + C2N) is estimated from parallel studies of nonlinear stress relaxation of the uncrosslinked polymer, taking into account the thermal history before and during irradiation. For substantial degrees of crosslinking, i.e., for R0′ = νx/νN > 0.4 (where νN is the concentration of network strands terminated by crosslinks), and for λ0 < 1.8, C2N agrees rather well with the value obtained from stress relaxation of the uncrosslinked polymer in the range of time scale where it is nearly independent of time (1.87 X 105 pascals). The corresponding value of νN is 2.3 × 10−4 moles/cm3, in good agreement with that obtained from viscoelastic measurements of the uncrosslinked polymer in the plateau zone (2.5 × 10−4). However, for R0′ ≅ 0.2, smaller values of C2N and νN are obtained, indicating that for low degrees of crosslinking the entanglements are not completely trapped. Also, for higher values of λ0, C2N and νN turn out to be somewhat smaller. Similar, less extensive results were obtained previously on a 1,2‐polybutadiene with somewhat higher vinyl content and a higher Tg. Crosslinked samples of both these polymers were subjected to equilibrium stress–strain measurements in simple elongation from the state of ease at higher strains up to Λ = 1.7. The results agreed closely with calculations from the three‐constant Mooney–Rivlin theory.
Kinetics of alkali‐catalyzed m‐cresol‐formaldehyde reaction
Authors: Malhotra H. C. , Gupta V. K. 
Published: April 2003

AbstractThe alkali‐catalyzed reaction of m‐cresol with formaldehyde carried out at 65°, 70°, 75° and 80°C and at pH 7, 8, 9, 9.4, and 10 follows second‐order kinetics. The rate is found to increase with increase of pH. The overall rate constant (k) has been resolved into stepwise rate constants (k1, k2, and k3) for the formation of monomethylol, dimethylol, and trimethylol cresol, respectively. For this purpose, the rate equations for the various possible steps have been given and the concentrations of the various methylol cresols formed determined. The experimental and calculated values of k at pH 10 and temperatures of 65°, 70°, and 80°C have been found to agree well within the experimental errors. Entropy of activation and the Arrhenius parameters for the overall reaction have also been calculated.
Casting of organic glass by radiation‐induced polymerization of glass‐forming monomers at low temperature. II. Optical strain of remaining stress type
Authors: Okubo Hiroshi , Yoshii Fumio , Kaetsu Isao , Honda Shigeharu 
Published: April 2003

AbstractPreviously it was found that casting could be carried out efficiently without strain formation by radiation‐induced polymerization of glass‐forming monomers. Two types of strain were observed in casting: thermal stream type, which was studied previously, and remained stress type. In this report, the effect of various factors on the formation of remaining stress‐type strain in radiation‐induced casting polymerization was studied. It was found that the molecular weight of prepolymer did not affect strain formation, while prepolymer concentration and viscosity of the system had a serious influence on strain formation. It could be deduced that this type of strain formed as a result of remaining inner stress due to poor relaxation of the shrinking stress. It was realized that less volume shrinkage of glass‐forming monomers accompanying casting polymerization reduced the strain formation of this type in radiation‐induced casting polymerization at low temperatures.
Poly(1,3,4‐oxadiazoles). Effect of structure on polymer properties
Authors: Varma I. K. , Geetha C. K. 
Published: April 2003

AbstractPoly(1,3,4‐oxadiazole‐2,5‐diylvinylene) and poly(1,4‐phenylene‐1,3,4‐oxadiazole‐2,5‐diylvinylene) were prepared by polymerizing different quantities of terephthalic acid (T), maleic acid (M), and hydrazine sulfate (HS) in the presence of fuming sulfuric acid. Homopolymers of M and T and various copolymers of M:T were prepared. The polymers were characterized by viscosity, IR, UV, and elemental analysis. Their solubility in different solvents was investigated. The relative thermal stability of the polymers was evaluated by TGA and DTA.
New coating materials prepared by radiation‐induced polymerization. I. Mar‐resistant coating composition and properties
Authors: Okubo H. , Kato M. , Yoshida M. , Ito A. , Kaetsu I. 
Published: April 2003

AbstractA mar‐resistant coating system was obtained by screening combinations of silicone and vinyl compounds. It was found that binary systems, such as the γ‐glycidoxypropyltrimethoxysilane–glycidyl methacrylate system, were excellent not only in mar resistance but also in adhesion to base resin polymers. Haze values of these coatings, after the sand‐falling test, reached less than 10%. The coating process consisted of three steps: the preparation of prepolymer, the coating to plastic surface, and the curing of the coating by heating. It was found that the prepolymerization step could be performed by irradiation very conveniently; the control of viscosity for coating application and thickness control could be possible without any gel formation. These coatings were also good in weather resistance due perhaps to the good adhesion to base resin and could be applicable to plastic spectacles, glazing materials, and a variety of other products.