bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic mechanical and thermal properties of fire‐retardant high‐impact polystyrene
Authors: Chang Eng Pi , Kirsten Rudy , Slagowski Eugene L. 
Published: April 2003

AbstractThe interaction of a series of fire‐retardant additives with high‐impact polystyrene (HIPS) has been inferred from their dynamic mechanical and thermal properties. High‐melting additives phase separate and act as inert filler in both the rubber and polystyrene phases, while low‐melting additives raise the Tg of the rubber phase and plasticize the polystyrene phase. Antimony oxide antiplasticizes the grafted rubber phase but acts as inert filler in the polystyrene phase. The impact strength of these fire‐retardant HIPS's shows good correlation with the integrated loss tangent of the rubber Tg peak indicative of large energy dissipation in the rubbery region during impact causing the matrix to craze or flow. It is also suggested that additives which are compatible with, and localized in, the polystyrene phase help retain the impact strength of HIPS.
Studies on the photo‐oxidation mechanism of polymers. VI. The role of commercial thermostabilizers in the photostability of poly(vinyl chloride)
Authors: Rabek J. F. , Canbäck G. , Rånby B. 
Published: April 2003

AbstractThis paper presents a study on the photolysis of PVC in the presence of different types of tin stabilizers. Using physicochemical methods such as ESR spectroscopy, conductivity titration, gel permeation chromatography, and absorption spectroscopy, the mechanism of PVC photolysis has been investigated. ESR spectroscopy shows that during UV irradiation of tin stabilizers, different types of free radicals depending on the chemical structure of the examined compounds are formed. It has been found that the presence of tin stabilizers does not significantly influence the photo‐oxidation and degradation of PVC but influences the crosslinking processes. The authors propose an interpretation of the free‐radical formation during UV photolysis of tin stabilizers and of the crosslinking acceleration mechanism.
Semicontinuous emulsion copolymerization of acrylonitrile, butyl acrylate, and styrene
Authors: Šňupárek Jaromír , Krška František 
Published: April 2003

AbstractSemicontinuous emulsion copolymerization of acrylonitrile (M1), butyl acrylate (M2), and styrene (M3) was investigated. The copolymerization proceeded under the conditions used with a high degree of conversion, whereby a stationary state characterized by a constant monomer mixture composition and a constant composition of the arising copolymer was achieved. From the analytically estimated free monomers and arising copolymer compositions, the reactivity ratios for the pair AN/BA r12 = 0.71, r21 = 1.17 and for the pair AN/Sty r13 = 0.06, r31 = 0.28 were calculated. The applicability of the reactivity ratios found was verified also for the ternary system acrylonitrile/butyl acrylate/styrene.
Randomly branched styrene/divinylbenzene copolymers. II. Solution properties and structure
Authors: Ambler M. R. , McIntyre D. 
Published: April 2003

AbstractThe [η] of randomly branched PSty/DVB continually decreases from linear polystyrene with increasing conversion. On the other hand, the relation of the 〈S2〉 to M of both low and high conversion series is equivalent, although the actual size is smaller than that of linear polystyrene of the same M. This fact, in conjunction with the previously published reactivity ratios, allows the following interpretation of the mechanism of copolymerization: namely, that branched molecules are formed in which the center core is higher in DVB content than is the periphery. Only about 1/7 of the available DVB units act as effective tetrafunctional branch points. An analysis of GPC data correlated with light scattering and viscosity dimensions allows the g value to be determined in the lightly and highly branched fractions. The viscosity ration is related to gx, where x is 0.65 for low conversion fractions (A series) and becomes 1.41 for high conversion fractions (B series). This change in exponent is postulated to arise from an increase in branching density as conversion increases. The ratio of the hydrodynamic radius to the radius of gyration is higher for branched than for linear polymers. The theta temperature (θ) in cyclohexane for randomly branched polystyrene compared to linear polystyrene is always higher and can be as much as 2° higher.
Thermal analysis of thermosetting phenolic compounds for injection molding
Authors: Siegmann A. , Narkis M. 
Published: April 2003

AbstractThe differential scanning calorimetry technique has been applied to investigate the curing of injection molding phenolic compounds. The data obtained include degree of cure, rate of curing, and heats and temperatures of curing as function of various heating rates, rate constants, energy of activation, and glass transition temperature. The curing temperature and heating rate were found to affect both the curing reaction kinetics and the final structure of the crosslinked network. The glass transition temperature changes continously with the extent of curing, approaching the cure temperature.
Preparation of crosslinked poly(styrene–g–N‐carboxyalkylated ethylenimine) as chelating resin
Authors: Saegusa Takeo , Kobayashi Shiro , Yamada Akira 
Published: April 2003

AbstractCarboxymethyl and ethyl groups were introduced into crosslinked poly(styrene–g–ethylenimine) (PSt–g–EI), consisting of a crosslinked polystyrene backbone with linear polyethylenimine branches, by the reaction of PSt–g–EI with monochloroacetic acid and β‐chloropropionic acid. Carboxyethylation was also performed by reaction of the PSt–g–EI with acrylic acid. The extent of the reaction was determined by the change in the nitrogen content of the resin. The adsorption of metal ions such as Cu2+, Cd2+, Hg2+, Ni2+, and Ca2+ by carboxyalkylated PSt–g–EI was examined. With the introduction of carboxyalkyl groups, the adsorption capacity for metal ions (per gram of resin) decreased, whereas the affinity of the resin for these ions increased.
Posttreatment effects on pore size distribution of loeb‐sourirajan‐type modified cellulose acetate ultrathin membranes
Authors: Ohya Haruhiko , Konuma Hozumi , Negishi Yoichi 
Published: April 2003

AbstractThe nitrogen gas adsorption isotherms at −195°C on modified cellulose acetate ultrathin membranes were measured, and the surface area of the pores was determined by the method employed by Cranston and Inkley. A relationship between reverse osmosis characteristics and the mean pore radius was correlated, and it was observed that any method (such as longer evaporation period, heat treatment, or reduction of swelling agent) reducing the mean pore radius to below 20–22 Å improves membrane characteristics of reverse osmosis separation significantly.
The ultimate polymer application: Resin‐bonded cellulose separators for lead–acid batteries
Authors: Dafler James R. 
Published: April 2003

AbstractBecause it represents a polymer system routinely used in a highly corrosive environment, the resin‐bonded cellulose separator is a paradigm of bad polymer application that succeeds. It succeeds because of the remarkable properties of cellulose itself, and through the formation of a highly modified structure that serves to protect both the resin and the cellulose in a reactive environment known to completely degrade both. X‐ray diffraction analysis was used to determine the quality of retained cellulose in lead–acid battery separators made by impregnating thick cellulose matrixes with phenolic resins. The hydrolytic weight loss of separators stored in battery acid at 52°C was also measured and related to x‐ray diffraction measurements of intensive degree of crystallinity and “qualitative perfection.” The x‐ray diffraction analyses and hydrolysis measurements are consistent with the formation of a copolymer between the cellulose and the impregnating resin. Treated and rewetted α‐cellulose displays a capability for reorganization, indicated by increases in intensive crystallinity and qualitative perfection that are absent in the resin‐bonded cellulose separator matrix. Rewetting of the separator matrix actually decreased the “qualitative perfection” of the cellulose present. X‐ray diffraction measurements indicate that extensive crystallinity of acid‐treated separators increases, due probably to the higher reactivity of the “so‐called” amorphous fraction of the cellulose present. The degree of crystallinity, an intensive measure, does not change significantly during acid treatment, but the “qualitative perfection” of the cellulose decreases with time of hydrolysis and increases in acid strength.
Casting of organic glass by radiation‐induced polymerization of glass‐forming monomers at low temperature. I. Optical strain of thermal stream type
Authors: Yoshi Fumio , Okubo Hiroshi , Kaetsu Isao 
Published: April 2003

AbstractIt was found previously that cast articles of transparent polymer without optical strain could be obtained efficiently in a very short time by radiation‐induced polymerization of glass‐forming monomers at low temperature. Two types of optical strain were observed in casting of these monomers: thermal stream type and remaining (inner) stress type strain. The mechanism of thermal stream‐type strain formation was investigated by following the heat and temperature change during cast polymerization in this report. It was found that the temperature difference between the upper and lower part of the sample was large and the temperature was much higher in the upper part than in the lower part under conditions of strain formation. Increase of heat removal from the sample surface decreased the temperature difference in the vertical direction and reduced the strain formation. It could be deduced that stream‐type strain formed as a result of thermal stream and it was retarded in radiation casting of glass‐forming monomers owing to high viscosity and low temperature.
Gas permeability and side chain structure of poly(γ‐benzyl L‐glutamate)
Authors: Oohachi Y. , Hamano H. , Yoshida T. , Tsujita Y. , Takizawa A. 
Published: April 2003

AbstractThree structural modifications of poly(γ‐benzyl L‐glutamate) (PBLG), forms A, B, and C, were prepared by varying the casting solvents and casting temperature. From x‐ray analysis, infrared absorption spectroscopy, differential scanning calorimetry, and viscoelastic measurements, it is concluded that form A of PBLG is characterized by intramolecular stacking between the benzene rings in the side chain, form B exhibits intermolecular stacking, and form C has no stacking. The transition which corresponds to the breakdown of stacking of form A at 135°C is irreversible, while that of form B at 110°C is reversible. The degree of stacking is larger for form A than for form B. These structural features of the side chain region reflect the permeation and sorption behavior of carbon dioxide. Breakdown of stacking between benzene rings causes an abrupt increase in permeability in both form A and form B, and the permeation behavior for form A is not reversible, as is suggested from the irreversibility of the transition. The larger the degree of stacking, the lower is the amount of sorption. Although stacking is considered to affect the sorption site (solubility) and molecular motion, its influence on solubility is more evident in the temperature range up to about 50°C.
Pyrolysis–molecular weight chromatography–vapor‐phase infrared spectrophotometry: An on‐line system for analysis of polymers. IV. Influence of cis/trans ratio on the thermal degradation of 1,4‐polybutadienes
Authors: Tamura Saburo , Gillham John K. 
Published: April 2003

AbstractThe influence of the cis/trans ratio of 1,4‐polybutadienes on the volatile products formed during temperature‐programmed thermal degradation to 15% weight loss has been investigated using a mass chromatograph (a gas chromatograph which directly provides mass numbers of resolved components of a mixture) and an “on the fly” vapor‐phase infrared spectrophotometer. In order of amounts, major volatile products were 4‐vinyl‐1‐cyclohexene (dimer), 1,3‐butadiene (monomer), cyclopentene, and 1,3‐cyclohexadiene. With increasing trans content, the relative quantities of 4‐vinyl‐1‐cyclohexene decreased strongly, cyclopentene increased strongly, 1,3‐butadiene decreased moderately, and 1,3‐cyclohexadiene increased moderately. For a high‐trans polybutadiene, increasing the heating rate produced relatively more monomer and dimer but less cyclopentene. Mass chromatograms from 1,4‐polybutadienes which had been heated to 15% weight loss in their prehistory were similar to those obtained from 1,2‐polybutadiene, indicating that 1,4‐polybutadiene undergoes isomerization prior to degradation. Mechanisms for the formation of the main volatile products of decomposition are discussed.
Properties of fabricated poly‐p‐phenylene
Authors: Gale David M. 
Published: April 2003

AbstractMechanical properties of fabricated poly‐p‐phenylene (PB) parts are compared to those of commerical polyimide. PB showed excellent retention of strength and stiffness at high temperature. Results of environmental exposure and properties of some PB composites are included. In general, PB parts have properties between those of commercial polyimide and carbon graphite.
Graft frequency of graft copolymers by chain transfer of growing polymer radicals to trunk polymers containing nitro groups
Authors: Nakamura Shigeo , Yamada Masaei , Matsuzaki Kei 
Published: April 2003

AbstractThe relationship between the chain transfer constant, extent of monomer conversion, and number of branches was derived for the graft copolymerization through chain transfer of growing polymer radicals to the pendent aromatic nitro groups on the trunk polymer. The equation derived enables us to predict the number of branches for a given monomer trunk polymer. The relationship obtained is compared with the experimental data previously reported for the graft copolymerization of styrene onto poly(vinyl p‐nitrobenzoate). The value of α′, the ratio of nitro groups with branches to those which are attacked by polystyrene radicals, is less than unity except for the graft copolymers obtained with high initiator concentrations and at early stages of the reaction. This lowering of α′ is attributed to the steric hindrance of branches already formed on the trunk polymer which prevents the attack of polystyrene radicals on the nitro groups and side reactions, such as reaction of the nitroso groups formed as an intermediate with styrene.
Studies in dyeing. II. Effect of crystal modification of disperse dyes on polyester dyeing at 130°C
Authors: Shenai V. A. , Parekh R. B. 
Published: April 2003

AbstractFour commercial disperse dyes were purified and their different crystal forms were prepared by crystallizing from different solvents or precipitating from their solutions in glacial acetic acid by dilution with water. These forms were found to have different melting points. They were dyed on polyester fibers at 130°C to fiber saturation values by changing the dyebath every 15 min. The effect of pretreatment of the dyes in an aqueous environment at different temperatures (60°, 100°, and 130°C) for 15–60 min in the presence and absence of a dispersing agent on the dye uptake values was also studied. Such treatments are shown to reduce the dye uptake. The implication of these treatments in practical dyeing are pointed out.
Some orientation studies on blown polyethylene films by infrared spectroscopy
Authors: McRae M. A. , Maddams W. F. 
Published: April 2003

AbstractInfrared dichroic measurements have been made on a number of blown polyethylene films for which x‐ray diffraction pole figure studies are reported in the three preceding papers; they complement them in some respects, and lead to several conclusions. Gauche chain conformations in loose chain folds in amorphous regions, characterized by bands at 1303, 1352, and 1368 cm‐1, show appreciable orientation in films with high‐stress orientation but very little with low‐stress orientation. Conversely, extended tie chains in amorphous regions, assessed by the band at 1080 cm‐1, are appreciably orientated with the more normal type of low‐stress film but not with high‐stress films. It is therefore possible, rapidly and inexpensively, to distinguish between the two types of orientation. The method for studying the orientation of extended tie chains is capable of further development. There is probably an empirical correlation between the dichroic ratios at 720 and 730 cm‐1 and the tear strengths and balances of the films with low‐stress orientation.
Biegeverhalten von kernverbund‐systemen
Authors: Lang Dr.‐Ing. G. 
Published: April 2003

AbstractThe data for the calculation of tensions and bendings of sandwich structures show that in case of bending loads, which are not free from transverse forces, shearing stress occurs in the core, and this stress influences the bending properties of polyethylene compound cores provided with aluminum facings. This influence is due to the viscoelastic properties of the polymers participating in the compound, dependent on the temperature and the load duration. Additives mixed into the core material produce, besides increased rigidity of the core itself, a more favorable bending behavior provided it has been possible at the same time to improve the firmness of the adhesive effect between the plates and the core by means of the additive. In this case the influence of the production conditions must be taken into consideration.
Curing behavior of two‐step phenolics by solvent extraction
Authors: Tonogai S. , Sakaguchi Y. , Seto S. 
Published: April 2003

AbstractIn examining the degree of cure of the novolac—hexamine system, higher‐boiling polar solvents such as methylcellosolve and cyclohexanone were found to have better extraction power than that of acetone, even for resins with a relatively high degree of cure. Making use of the difference in their extraction power, the cured resins could be fractionated into four portions, i.e., acetone soluble, acetone insoluble but methylcellosolve soluble, methylcellosolve insoluble but cyclohexanone soluble, and cyclohexanone insoluble. The formation and subsequent diminution of the soluble intermediates and the increase of insoluble crosslinked resins in the curing process were shown clearly by plotting the amount of each fraction against curing time at various temperatures. Further, the same extraction procedure was applied to the resins cured under reduced pressure. The curing reaction was markedly delayed in the latter case. Based on the remarkable difference in the curing behavior under pressure, a curing mechanism has been proposed in which the moisture contained may acelerate the decomposition of hexamine, thus enhancing the reactivity of the resin system.
Solubility criteria for a thermally stable polymer determined by gas–solid chromatography
Authors: Dinçer S. , Bonner D. C. 
Published: April 2003

AbstractThe Gibbs energy of adsorption, the Flory‐Huggins interaction parameter χ, and a specific interaction parameter A, based on hydrogen‐bonding and charge‐transfer complexing properties of solvents, are obtained by gas—solid chromatography for a type of polyquinoxaline denoted as PQF. Interactions between 40 organic solvents and PQF have been determined at 176.35° and 200.85°C. PQF is an aromatic, heterocyclic polymer which is at least partially soluble in several organic solvents. The parameters χ and Λ and the solubility parameters of solvents are proposed to be the determining factors for miscibility of a PQF—solvent pair.
Photostabilization of commercial polypropylene by a hindered amine stabilizer
Authors: Allen N. S. , McKellar J. F. 
Published: April 2003

AbstractThe photostabilization of commercial polypropylene by a hindered amine stabilizer is examined by luminescence and ESR spectroscopy. The presence of the amine stabilizer inhibits the photolysis of the α,β unsaturated carbonyl impurity groups present in the polymer. Examination by ESR, of the stabilized polymer before and after irradiation shows the development of a highly stabilized free radical indicating that the stabilizer can act as an ultraviolet stable antioxidant. Possible mechanisms whereby the hindered amine inhibits the photolysis of the α,β unsaturated carbonyl groups are discussed.
Grafting vinyl monomers onto wool fibers. I. Graft copolymerization of methyl methacrylate onto wool using V5+–thiourea redox system
Authors: Nayak Padma L. , Lenka Subasini , Pati Nrusingh C. 
Published: April 2003

AbstractThe graft copolymerization of methyl methacrylate in wool fibers was investigated in aqueous solution using V5+—thiourea redox system. The rate of grafting was determined by varying monomer, thiourea, acidity of the medium, temperature, nature of wool, different acrylic monomers, and reaction medium. The graft yield increases significantly by increasing reaction time in the initial stages of the reaction but it does slow down on prolonging the duration of grafting. The effect of increasing monomer concentration brings about a significant enhancement in the graft yield. The graft yield increases with increasing thiourea concentration, but beyond 0.0075M, the percentage graft yield decreases. The graft yields are considerably influenced by chemical modification prior to grafting. Wool reduced with thioglycolic acid is more susceptible to grafting than untreated wool; the opposite effect is noted in the case of trinitrophenylated and esterified wools. A suitable kinetic scheme has been proposed and the rate equation has been evaluated.
Saccharide radicals induced by UV irradiation at room temperature
Authors: Kubota Hitoshi , Ogiwara Yoshitaka , Matsuzaki Kei 
Published: April 2003

AbstractThe stability of saccharide radicals induced by UV irradiation at room temperature and the ability to initiate polymerization of acrylamide were investigated. UV light of 220 < λ < 300 nm was proved to form saccharide radicals effectively at room temperature. ESR signal intensity of the irradiated saccharide was in the order of sucrose > methyl‐α‐D‐glucopyranoside ≫ cellobiose > D‐xylose > D‐glucose α D‐fructose. The saccharide radicals were fairly stable at room temperature, however, the markedly declined in amount as the samples were brought to their own melting points or allowed contact with water. When an aqueous solution of acrylamide was added to the irradiated saccharide, polymerization was initiated and the conversion increased with an increasing amount of the preirradiated saccharide. Regarding the kind of saccharide, the conversion decreased in the following order: sucrose > methyl‐α‐D‐glucopyranoside > cellobiose > D‐glucose, which indicated a good agreement with the magnitude of ESR signal intensity.
Fast determination of fatty acids in oil‐utilizing resins by NMR spectroscopy
Authors: Rybicky Jaroslav 
Published: April 2003

AbstractThis work describes the determination of oil either as such or in oil‐utilizing resins such as alkyds and urethanes, by means of NMR techniques. Both the qualitative and quantitative analyses are demonstrated and the accuracy is assessed. Typically, the complete analysis of an alkyd resin takes less than 1 hr.