bluuebunny/crossref_metadata_2025_split huggingface dataset:
Environmental stress relaxation studies of polymers: Effect of temperature on polyethylene–alcohol system
Authors: Nisizawa Mizuho 
Published: April 2003

AbstractThe method of stress relaxation has been used to study the plasticizing effect of sorbed alcohols on polyethylene as it changes with temperature. From the observation of the stress relaxation in polyethylene under alcohols at various temperatures, the activation energy of penetrant‐enhanced relaxation of polyethylene caused by alcohols was obtained.
Pyrolysis products of untreated and flame retardant‐treated α‐cellulose and levoglucosan
Authors: Wodley Frank A. 
Published: April 2003

AbstractA typical gas chromatogram of the volatile pyrolysis products of untreated α‐cellulose contains 39 peaks; however, mass spectral data indicate that at least 59 compounds, with molecular weights less than about 150, are present. A total of 37 compounds have been identified, 13 of which have not been previously reported. Most of the newly identified compounds contain a benzene ring, indicating that these compounds may be products of reactions between initial volatiles. A comparison of the products generated in the temperature range of 330°–440°C indicates that the formation of pyrolysis products is essential independent of temperature. Comparisons of the chromatograms obtained for untreated levoglucosan and cellulose indicate that most of the decomposition of cellulose probably forms levoglucosan which then decomposes to yield the observed pyrolysis products. In addition, the products of flame retardant‐treated levoglucosan are essentially the same as those of cellulose with the same retardant treatment. This suggests that the retardants act on the levoglucosan formed in the decomposition of the cellulose rather than on the cellulose directly.
Fracture toughness of glass fiber‐reinforced acetal polymer
Authors: Hardy G. F. 
Published: April 2003

AbstractThe critical stress field intensity factor for crack propagation,KIc, was determined for a large number of glass fiber‐reinforced acetal copolymer compositions and for the unfilled resin. The results were interpreted in terms of a model previously proposed for the tensile behavior of these materials. TheKIccould be regarded as a linear function of the contribution of the fiber reinforcement to the tensile strength, but was otherwise substantially independent of the amount and length of the fibers and the nature of the fiber finish. From this relationship it was estimated that the inherent flaw size of these materials was of the order of magnitude of the fiber length. The observed variation ofKIcwith loading rate was also consistent with the model. The notched Izod impact strength of these same materials was shown to be roughly equivalent toGIc, the critical strain energy release rate, or fracture energy per unit area, which can be computed fromKIcby the methods of fracture mechanics. The behavior of these crack propagation parameters is consistent with the previous hypothesis that failure is initiated by loss of adhesion between the matrix and those fibers which lie transverse to the applied load.
Polymers containing the s‐triazine ring. II. Synthesis of poly(s‐triazinylenehydrazones)
Authors: Oikawa Eizo , Tatsuishi Hirofumi 
Published: April 2003

AbstractPoly(2‐methyl‐ or 2‐phenyl‐s‐triazinylenehydrazones) were prepared both by dehyhydration of dihydrazino‐s‐triazines with terephthalaldehyde and by dehydrochlorination of dichloro‐s‐triazines with terephthalaldehyde dihydrazone. The structure of the polymers was confirmed by infrared spectrometry and elemental analyses in comparison with those of a model compound. Dehydration yielded soluble polymers, while the dehydrochlorination yielded insoluble polymers. Most of the polymers degraded at about 350°C, and the polymers of higher molecular weight showed better thermal stability. The thermal behavior of the polymers indicated that the phenyl‐substituted polymers obtained by dehydrochlorination and the methyl‐substituted polymers obtained by dehydration had a degree of polymerization similar to that of the phenyl‐substituted polymers obtained by dehydration. The soluble polymers could form chelate polymers, these took two accelerated decomposition phases. The lower phase suggested a decomposition accelerated by a metal. The higher phase, in which the chelate polymers decomposed more rapidly at a higher temperature (above 400°C) than their ligand polymer, was related to the atomic number and the electro‐negativity of the metals. The formation of decomposition products, guanamines and nitrile compounds, in all cases indicate the preferential scission of nitrogen‐nitrogen bonds.
Degradation of polymers by high‐speed stirring
Authors: Nakano Akihiko , Minoura Yuji 
Published: April 2003

AbstractBenzene solutions containing either poly(ethylene oxide) or poly(methyl methacrylate) or both of varying concentrations were prepared, stirred at a speed of 30,000 rpm, and the effects of concentrations of the same species or different species of polymers on the degradation of the polymers were investigated. Within experimental error little difference was observed in the [η] curves measured for each degraded polymer in spite of change in concentration. It is clear that the degradation of polymer with high‐speed stirring in the concentration range 1–4% w/v is not caused by the interaction of polymer chains.
Study of the oligoester maleinates containing an isocyanuric ring by infrared spectroscopy
Authors: Alaminov H. , Proynova Z. 
Published: April 2003

AbstractProcesses taking place in crosslinked oligoester maleinates containing an isocyanuric ring were studied by means of infrared and ESR spectroscopy and heating from 110° to 600°C. By determining the optical density of the carbonyl groups at 1690 cm−1, of the CH2 groups at 1460 cm−1, ether and ester groups at 1120 and 1260 cm−1, and vinyl groups at 935 and 990 cm−1, their mutation by hardening and tempering of the polymers was followed. The investigation shows that the carbonyl absorption of the oligoester maleinates containing an isocyanuric ring is double and that of the oligoester propylene‐glycol maleinate phthalate is single. By modification of the isocyanuric oligoester maleinates with phthalic, adipic, sebacic, and other acids, and increase of the speed of isomerization of maleric groupings to fumaric is observed. By building of isocyanuric links in oligoester maleinates, a more stable structure is obtained. Above 330°C, isocyanuric links probably regroup into polycyanic links. The typical carbonyl absorption precipitously decreases at 400°C and disappears altogether at 600°C. On the basis of the investigations carried out, it is assumed that, in the process of hardening and thermodestruction of the polymers investigated, and radical processes obviously play an essential part
A study of the fine structure of cellulosic fibers by level‐off degree of polymerization measurements
Authors: Zeronian S. H. 
Published: April 2003

AbstractThe crystallization of disordered and partly disordered cellulose on hydrolysis with boiling dilute mineral acid was studied and the level‐off degree of polymerization (LODP) of cotton after treatment with inter‐or intracrystalline swelling agents was determined. The LODP, of cotton and of cotton which had been swollen in morpholine were similar, indicating that the LODP of cotton cellulose was not affected by this intercrystalline swelling agent. It appears that the aggregates of cellulose chains present in cotton which has been treated with aqueous NaOH of mercerizing strength and then washed with water are not uniformly accessible to hydrolyzing acid and that the accessibility to the acid is not changed when the cellulose is dried. The LODP of samples of mercerized, ethanol‐washed, never‐dried cotton that had been acetylated was obtained and the results are discussed in terms of current views on the fine structure of cotton.
Deposition of acrylate polymers in wool fibers
Authors: Simpson W. S. 
Published: April 2003

AbstractThe factors influencing the kinetics of formation of acrylate polymers in wool fibers are described. Allyl methacrylate and N,N′‐methylenebisacrylamide were found to copolymerize satisfactorily with methyl or ethyl acrylate to form crosslinked polymers. Conditions were found for almost complete conversion of the available monomer to polymer in a batch‐type process.
Intercrystalline crosslinking of polyethylene
Authors: Brody H. 
Published: April 2003

AbstractThe heat distortion temperature (British Standards Method 102C) and DTA nominal melting point of high density polyethylene have been raised to 140°C by nonrandom crosslinking in which the crosslinks are superimposed on the existing semicrystalline structure. The crosslinking agent was a mixture of dicumyl peroxide and allyl methacrylate, and the crosslinking temperature was 120°C, just below the crystal melting range. In contrast, random crosslinking by the same system above the melting range at 160°C lowered the HDT (heat distortion temperature). Conventional peroxide crosslinking also lowered the HDT. The gel swelling of randomly crosslinked polyethylene was higher than that of nonrandomly crosslinked polyethylene having the same gel content. This dependence of the gel swelling on the crosslink distribution can be correlated with the HDT. The effect of γ‐radiation and carbon black loading on the HDT has also been studied.
Graft copolymerization of vinyl monomers on modified cottons. III. Grafting of acrylonitrile and methyl methacrylate on cyanoethylated cotton by the ceric ion method
Authors: Kantouch A. , Hebeish A. , El‐Rafie M. H. 
Published: April 2003

AbstractThe interaction of acrylonitrile and methyl methacrylate with cyanoethylated cotton in the presence of ceric ion has been studied under a variety of conditions. Increasing the reaction time, the monomer concentration, and the temperature favorably influences the degree of grafting. The same holds true for initiator concentration up to a certain limit, after which a decrease in the graft yield was obtained. On the other hand, ceric consumption during grafting and oxidation increases by increasing the magnitudes of all these factors. However, the consumption during grafting is always higher than that during oxidation. The graft yields obtained with cyanoethylated cotton are greater than those of the control, being increased by increasing the degree of substitution (D.S.) of the cyanoethylated cotton, suggesting that the cyanoethyl groups afford additional sites of grafting. On the other hand, the ceric consumption during oxidation of cyano‐ethylated cotton was much lower than that of the control, being increased also by increasing the D.S., indicating perhaps that ceric ion attacks the cyanoethylated cotton exclusively at the cyanoethyl groups. Based on these findings, a scheme for the mechanism of reaction of a vinyl monomer with cyanoethylated cotton was proposed.
Predicting joint sealant performance of elastomers by computer simulation. III. Simulation of single‐ and multi‐step extension of a stress‐relaxing material
Authors: Catsiff E. H. 
Published: April 2003

AbstractComputer simulation of the extension of a joint seal that had fully relaxed in a compressed configuration indicated that exceptionally high stresses were engendered if the extension occurred in a single step, as provided in certain “performance tests.” When the same amount of extension was simulated by a stepwise procedure, with the assumption of full relaxation after each step, not only were the stresses smaller, but the stress concentration factors in the extreme corners of the joint seal were much reduced, so that the likelihood of failure under such conditions would appear to be remote. This stepwise extension pattern is considered to be more representative of real joint behavior than the “accelerated performance test.”
Effects of symmetrical bonding defects on tensile shear strength of lap joints having ductile adhesives
Authors: Schonhorn Harold , Ryan F. W. , Wang Tsuey T. 
Published: April 2003

AbstractIn this paper we examine the effect on joint strength of depleting the bond line of a relatively flexible adhesive (polyethylene) while maintaining a constant adhesive film thickness. It is shown that the tensile shear strength of a lap specimen is not governed by edge effects but rather by the bonded area. By using limit analysis of the plasticity theory, we demonstrate why the tensile shear strength of the joint is insensitive to stress concentrations at the bonding defects.
The chemistry of furfuryl alcohol resins
Authors: Barr J. B. , Wallon S. B. 
Published: April 2003

AbstractFurfuryl alcohol resins contain a broad spectrum of compounds. The distribution of these compounds in a given resin varies with the manufacturing conditions. A resin containing a high proportion of low molecular weight constituents has been prepared and separated into fractions. Twelve compounds were separated from the resin; four of these are new compounds. The lower molecular weight constituents can be arranged into four major classes: polyfurfuryl alcohols, polyfurfuryl furans, methyl‐substituted polyfurfuryl furans, and polyfurfuryl ethers.
The influence of precure dilation on the stress–strain properties of ethylene–propylene terpolymer networks
Authors: Kirkham M. C. 
Published: April 2003

AbstractA study has been made of the influence of a dilating liquid, present during vulcanization, on the stress–strain behavior of EPT vulcanizates. Stress–strain measurements performed on the vulcanizates after extraction of the dilating liquid, taken over a range of strain rates, indicate the effective absence of time‐dependent behavior and suggest that a close approach to equilibrium has been achieved. From the experimental data, values of the C1 and C2 constants of the empirical Mooney‐Rivlin equation were derived. It was found that both C1 and C2 decreased with increased precure dilation, C2 decreasing more rapidly than C1. The observed decrease in C1 is less than would be predicted by simple analogy with the Gaussian modulus; it is suggested that this difference might be explained by changes in network configuration and topology associated with the precure dilation.
Optimization of the filler content of filled polyester resin
Authors: Jones W. C. , Fricke A. L. 
Published: April 2003

AbstractA method for the constrained optimization of the filler content in polyester resin was demonstrated. The fillers investigated included marble, clay, pecan shell flour, and hollow microspheres in various concentrations. The method of optimization included an experimental design to generate data and a polynomial regression analysis to determine the mechanical property constraint functions. The constraints were well approximated by linear functions, and linear programming was used to find optimum compositions for several possible applications.
ESR study of intramolecular energy transfer in the radiolysis of cellulose thenoates
Authors: Singh Sujan , Hinojosa Oscar , Arthur Jett C. 
Published: April 2003

AbstractThe substitution of 2‐thenoyl, 5‐methyl‐2‐thenoyl, 2‐thiopheneacryloyl, 5‐bromo‐2‐thenoyl, and 5‐bromo‐2‐thiopheneacryloyl groups on fibrous cotton cellulose increased the radiation resistance of cellulose, as indicated by the retention of the breaking strengths of the modified fibrous celluloses at high dosages of γ‐radiation, as compared with that of irradiated, unmodified fibrous cellulose. The presence of electropositive or electronegative substituents on the thiophene groups did not reduce the radioprotective effects of these groups for cellulose. Crosslinking of the cellulose thenoates in 1,3‐di(4‐pyridyl)‐propane did not significantly reduce the radiation resistance of the thenoates. Examination of the ESR spectra of irradiated cellulose and cellulose thenoates indicated that the site of the long‐lived free radicals on the irradiated cellulose molecules was not changed by the chemical modification. However, the concentration of long‐lived free radicals in irradiated cellulose thenoates, at a given radiation dosage, was less than that in irradiated cellulose. The localization of energy on carbon C1 or C4 of the cellulose molecule, which leads to depolymerization and loss in breaking strength of fibrous cellulose, was decreased. The radioprotective effects of thiophene groups for cellulose were similar to those of furan and benzenoid groups.
Rheological properties of molten polymers. II. Two‐phase systems
Authors: Han Chang Dae , Yu Thomas C. 
Published: April 2003

AbstractA study is carried out for characterizing two‐phase systems of molten polymers by their viscous and elastic properties. The two‐phase systems chosen for study are blends of polystyrene and polypropylene, and blends of polystyrene and high‐density polyethylene. For the study, measurements of wall normal stresses are made by use of a capillary melt rheometer described in part I of this series. The concept of the “exit pressure” is used to determine the elastic properties of the two‐phase polymer systems. The present study shows anomalous viscous and elastic properties of two‐phase systems, which are difficult to predict from knowing the viscous and elastic properties of their individual components. A detailed discussion is given on the state of dispersion of two incompatible polymer systems in the molten state, by presenting pictures of the microstructure of the extrudate samples. The state of dispersion appears to vary depending on the blending ratio, extrusion temperature, melt viscosities of individual components, and blending method.
Molecular weight distribution and rheological properties of polyisobutylene solutions
Authors: Nishida Noboru , Salladay David G. , White James L. 
Published: April 2003

AbstractThe molecular weight distribution of a series of polyisobutylenes was determined using osmotic pressure measurements, gel permeation chromatography, and intrinsic viscosity. All of the polymers except for one, a blend of the highest and lowest molecular weight constituents, had similar moderate molecular weight distributions. The “extended chain length” method of calibrating the gel permeation chromatograph for polyisobutylenes was found to be effective. Steady state and transient shear stresses and normal stresses were measured on 5% decalin solutions of these polymers. The zero shear viscosity increased with the 3.3 power of molecular weight, and the zero shear normal stress coefficient (σ11 − σ22)/Γ2 varied with the 7.5 power. Relative elastic memory as measured by (σ11 − σ22)/σ12 or stress relaxation increased with increasing molecular weight (and at constant number‐ or weight‐average molecular weight) with breadth of distribution. Stress overshoot also correlated with this tendency.
The mechanical behavior of microporous polyurethane foams
Authors: Whittaker R. E. 
Published: April 2003

AbstractThe mechanical behavior of microporous polyurethane foams used in poromeric materials can be described by use of a model comprising of struts of square cross section arranged in a cubical lattice. The model was initially proposed by Gent and Thomas to describe the properties exhibited by natural rubber latex foams. The microporous polyurethane foams used in poromerics are in general much stronger than natural rubber foams, and it has been found that their tear and tensile properties are dependent on the size of the largest pore, which can be up to 20 times greater in diameter than the average pore size. The behavior of the polyurethane foam in compression can be satisfactorily described by use of this cubical model and shape factor theories from polymer engineering.
Polymer miscibility in organic solvents and in plasticizers—a two‐dimensional approach
Authors: Chen Show‐An 
Published: April 2003

AbstractFrom thermodynamic considerations based on associated solution models and from the Hansen's three‐dimensional solubility parameter concept, it is found that the solvent power of an organic liquid for a given polymer can be characterized by two parameters, δh and χH, where δh is the hydrogen‐bonding solubility parameter of the liquid, and χH is a term which takes account of the dispersion and polar interactions between the liquid and the polymer and of the effects due to temperature and molecular size of the liquid. It is also found that Hansen's solubility sphere for the polymer can be represented as a solubility circle in the proposed χH−δh plane. The proposed approach is applied successfully to polymer–plasticizer systems.
Compressibility of polyethylene melts at low pressures
Authors: Chung Chan I. 
Published: April 2003

AbstractBranched polyethylene has quite different rheological and physical properties from its linear homologue. Despite their many different properties, the densities of linear and branched polyethylene melts at atmospheric pressure have been reported to be identical at all temperatures. However, it was not known whether their melt densities at a given temperature would also be identical at all pressures. In this investigation, the compressibilities of one linear and two branched polyethylene melts at 160°C, 190°C, and 220°C were studied, and it was found that they had an identical compressibility over the present experimental pressure range of ca. 0–455 psi (0–31 atm). Both the specific volume and the density at each temperature could be very accurately expressed as linear functions of pressure for this pressure range. Time‐dependent compressive property was not observed within the present low pressure range.
Structure–physical property relationships in peroxide‐cured butadiene–styrene copolymers
Authors: Ambrose R. J. 
Published: April 2003

AbstractStructure–physical property relationships in high‐vinyl butadiene–styrene copolymers have been determined for samples cured with dicumyl peroxide under the same conditions. Three different structures, butadiene–styrene–butadiene (B–S–B) triblocks, butadiene–styrene (B–S) diblocks, and random butadiene–styrene copolymers, have been examined. Flexural modulus increases with increasing styrene content owing to the inherent stiffness of a polystyrene backbone. Swelling increases whereas hardness and heat distortion temperature decrease with increasing styrene content. This behavior is explained by the decrease in crosslink density with increasing styrene content in all structures. Heat distortion temperatures of the B–S–B and B–S networks are superior to the heat distortion properties of the random structures. The B–S–B structure is the most solvent resistant, followed by the random copolymers, with the B–S structures swelling to the greatest extent. Swelling differences between the B–S–B and random networks decrease with increasing styrene content, while swelling differences between the B–S–B and B–S networks increase with increasing styrene content. These results are explained by the nature of the crosslinking reaction and the number of loose ends present in each network.