bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of hysteresis on tensile and fatigue failure in rubbers
Authors: Payne A. R. , Whittaker R. E. 
Published: April 2003

AbstractThe failure criterion developed by Harwood et al. between energy input to break and hysteresis at break for amorphous rubbers has been related to the fatigue and cut growth properties of the rubber which are based on the tearing energy theory. It is found that the constant K in the hysteresis failure criterion is a function of the cut growth constant G and the inherent flaw size C0. The effect of adding fine particulate fillers to amorphous rubbers on the hysteresis and fatigue properties is considered and shown to be in agreement with the theory.
Thermal analysis of polymers. VIII. Dilatometric and thermal optical behavior of sulfur
Authors: Miller Gerald W. 
Published: April 2003

AbstractThe use of combined modes of thermal analysis by differential thermal analysis (DTA), thermomechanical analysis, and thermal depolarization analysis (TDA) presents a more illustrative picture of the phase transitions and behavior of the allotropes of sulfur. Volumetric changes suggest the Tg of polymeric sulfur to occur at 35°C. Changes in depolarized light level and an abrupt change in volume at 77°C identify this change as a first‐order fusion. The depolarized light behavior of sulfur, which has been quenched from 200°C to −190°C, illustrates the probable existence of a mesomorphic state of sulfur between 100° and 122°C. Polymeric sulfur is thermally bleached near −150°C.
Compatibility of polystyrene and poly(methyl methacrylate) in benzene. Effects of molecular weight and temperature
Authors: Hong S.‐D. , Burns C. M. 
Published: April 2003

AbstractThe incompatibility of polystyrene and poly(methyl methacrylate) in benzene was examined at 20.1°, 40.0°, and 60.2°C. The incipient cloud points of solutions of equal weights of the two polymers were determined by a novel photometric method. Polystyrene samples with weight‐average molecular weights in the range of 3.27 × 105 to 6.43 × 104 and poly(methyl methacrylate) samples with weight‐average molecular weights in the range of 8.97 × 105 to 8.76 × 104 were used. Models describing the dependence on molecular weight of the critical concentration of a ternary polymer–polymer–solvent system, presented by Fuchs and by Kuhn et al., were examined in light of the experimental data. A modified model is proposed which gives an improved correlation of these results.
Rheology of concentrated suspensions
Authors: Chong J. S. , Christiansen E. B. , Baer A. D. 
Published: April 2003

AbstractThe dependence of the viscosities of highly concentrated suspensions on solids concentrations and particle size distributions is investigated by using an orifice viscometer. Based on the extensive amount of data on pertinent systems, an empirical equation which correlates the relative viscosities of suspensions (or relative moduli of filled polymeric materials) as a function of solids concentrations and particle size distributions is proposed. The equation has a constant which characterizes size distributions of spherical particles and can be determined experimentally without measuring viscosities. For uniform‐size spherical particles, it reduces to the well‐known Einstein equation at dilute solids concentrations.
Unusual film‐forming properties of aromatic heterocyclic ladder polymers
Authors: Arnold F. E. , Van Deusen R. L. 
Published: April 2003

AbstractA new method of obtaining films of aromatic heterocyclic ladder polymers has been found which circumvents casting from high‐boiling acidic solvents. The BBL ladder polymer has been formed into tough, durable films by collecting suspensions of the polymer obtained from acid reprecipitations upon a fritted glass funnel. After drying, the polymer can be removed as film, with thickness dependent upon the amount of material used. Such a film has a tensile strength of 9,600 lb/in.2 as compared to a tensile strength of 16,000 lb/in.2 obtained from the same polymer when cast from methanesulfonic acid solution.
The rapid identification method of additives in polypropylene by mass spectrometry
Authors: Yoshikawa T. , Ushimi K. , Kimura K. , Tamura M. 
Published: April 2003

AbstractFor the rapid identification of additives such as antioxidant, ultraviolet absorber, and slipping agent, polypropylene containing such additives was heated in a tube connected directly to the inlet system of a mass spectrometer. The vapor of the additives evaporating out of the polypropylene was led to the reservoir and then submitted to mass spectrometry to give spectra for identification.
Hymatomelanic acids as polyelectrolytes. I. Viscometric and osmometric studies
Authors: Ghosh Kunal , Mukherjee S. K. 
Published: April 2003

AbstractThe polyelectrolyte character of four natural and ten synthetic hymatomelanic acids, synthesized from possible monomers both in the presence and absence of catalysts, was established by means of viscosity measurements. Intrinsic viscosities were evaluated for the purpose of comparison. The number‐average molecular weights of some typical natural and synthetic hymatomelanic acids were determined from osmotic pressure measurements. Using the Flory‐Fox relationship in an approximate manner, the root‐mean‐square average end‐to‐end separations were also evaluated.
Kinetics of sulfur‐free thiuram vulcanization
Authors: Ducháček Vratislav 
Published: April 2003

AbstractSulfur‐free thiuram vulcanization has been investigated at temperatures from 160° to 190°C over 0.5 to 600 min. Continuous measurements in a VUREMO curemeter were used to estimate the extent of crosslinking, which was plotted against cure time. Simultaneously the values of the network chain density were calculated from swelling measurements on the vulcanizates. The cure curves show clearly an induction period (ti), then fast crosslinking, a partial degradation, a “long‐time” crosslinking, and finally a slow, limited degradation. Apart from the induction period, the kinetic graphs are satisfactory represented by a rate equation assuming three independent first‐order reactions: fast crosslinking, degradation, and slow crosslinking. The rate equation contains seven kinetic parameters. Over the temperature range studied, there is no difference between the values of activation energy for fast crosslinking, for degradation, for slow crosslinking, and for t. Due to the presence of thiourea, the values of the induction period, the rate constant, and the extent of slow crosslinking are decreased. Simultaneously the activation energies calculated from degradation and slow crosslinking are significantly increased. On the basis of the above results, the mechanism of the sulfur‐free thiuram vulcanization, in which ionic and radical reactions take place, is discussed.
Particle production by polymer pyrolysis: Effect of carbon monoxide
Authors: Fischer Wm. H. , Lodge J. P. 
Published: April 2003

AbstractThe effects of carbon monoxide and water vapor on the production of condensation nuclei during the pyrolysis of various polymers were investigated. Carbon monoxide reduced nuclei production while H2O increased it. The effect of the two combined was variable and unpredictable. The necessity for and the possible direction of additional investigation is pointed out.
Aromatic rings as cure sites for EPM elastomers
Authors: Holmquist H. E. , Proskow S. , Barney A. L. 
Published: April 2003

AbstractTerpolymers of ethylene and propylene with 4‐phenyl‐, 4‐o‐tolyl, 4‐p‐tolyl, and 4‐(1‐naphthyl)‐1‐butenes were vulcanized with bisbenzylic halides in the presence of highly acidic clays. The halides include bischloromethyldurene, p‐bischloromethylbenzene, and p‐bisbromomethylbenzene. Since the polymers contain no olefinic unsaturation, the crosslinking is achieved by electrophilic attack of the halide on the pendant aromatic rings. The order of activity is naphthyl > tolyl > phenyl. The new curing system also reacts with olefinic unsaturation. Thus, an EPDM elastomer and SBR rubber, the latter containing both aromatic rings and double bonds, were also readily crosslinked.
Ultraviolet stability of polyimides and polyamide–imides
Authors: Alvino W. M. 
Published: April 2003

AbstractThe ultraviolet stability of polyimides and polyamide–imides was determined in both a wet and dry environment. Films have been exposed to these environments for 3000 and 6000 hr, respectively. The polymers are not stable to UV radiation (2900–4000 Å); serious deterioration of the mechanical properties occurs under both wet and dry conditions with the former giving rise to greater damage. The polyamide–imide polymer is more unstable to UV radiation than the two polyimides evaluated; however, it is more resistant to hydrolysis as indicated from rate data obtained from a kinetic analysis of the mechanical property degradation curves. The electrical properties of the polymers are relatively unaffected in the dry environment but begin to deteriorate as the polymer becomes brittle. In the wet environment these properties begin to deteriorate more rapidly. Dissipation factor and dielectric strength are the properties most affected.
A study of the thermal behavior of graft copolymers of wool and methyl methacrylate
Authors: Varma D. S. , Sarkar R. K. 
Published: April 2003

AbstractThermal behavior of the natural and chemically modified wool fibers (treated with sodium hydroxide and formic acid and reduced with sodium bisulfite and thioglycollic acid) and of the graft copolymers of natural and modified wool with methyl nethacrylate (MMA) monomer was studied using dynamic thermogravimetry in air at a heating rate of 6°C/min to 600°C. The thermograms showed three distinct regions of weight loss for all the cases. A comparison of the temperatures of various percentage decompositions reveals that the thermal stability increased slightly with chemical modification of wool as compared to natural wool. Caustic soda and sodium bisulfite probably forms more stable lanthionine linkages, whereas formic acid improves the thermal stability perphas by modifying the noncrystalline region of the fiber. In the case of natural wool after graft copolymerization with MMA, thermal stability improves up to 325°C probably owing to the formation of new crosslinks, but after 325°C the thermal stability decreases owing to early decomposition of the polymer as compared to wool fiber. Similar effects are observed in all the chemically modified fibers except in wool reduced with sodium bisulfite, where thermal stability is found to increase after grafting even at higher temperature. The thermal stability was also computed from the primary thermograms by calculating the integral procedural decomposition temperature; the results show that thermal stability increases slightly with chemical modification of wool as compared to natural wool. In the case of natural wool with graft copolymerization with MMA, the overall thermal stability decreases, because the decrease of thermal stability after 325°C seems to be more prominent than the increase in thermal stability before 325°C. The same effects are observed in all the chemically modified fibers, except for fibers reduced with sodium bisulfite, where the overall thermal stability increases slightly with increase in graft‐on.
The mechanism of liquid transport through swollen polymer membranes
Authors: Paul D. R. , Ebra‐Lima O. M. 
Published: April 2003

AbstractThe pressure‐driven transport of liquids employed in reverse osmosis has been shown to occur by a solution‐diffusion mechanism in highly swollen polymer membranes. A theory based on this mechanism was successfully used earlier to correlate permeation fluxes for such membranes. Positive confirmation of this theory is provided here by direct measurement of the proposed concentration gradient. A study of the temperature dependence of the liquid diffusion coefficient in the polymer membrane has provided additional evidence of a hydrodynamic regime of diffusion in highly swollen membranes. It is also shown that the proposed ceiling flux in reverse osmosis is equal to the pervaporation flux.
Hydroboration of diene polymers
Authors: Minoura Yuji , Ikeda Hiroharu 
Published: April 2003

AbstractDiene polymers (i.e., polyisoprene, polybutadiene, and butadiene—styrene copolymers) were hydroxylated in tetrahydrofuran by hydroboration with diborane and subsequent alkaline oxidative hydrolysis. The strong, broad infrared absorption of the product at 3340 cm−1 shows the introduction of hydroxyl group. The properties of hydroxylated diene polymers depend upon the extent of hydroxylation. The less hydroxylated polymers are rubbery. As the extent of hydroxylation increases, the product becomes a white thermoplastic which is soluble in alcohol. The hydroboration of diene polymers with diborane is very rapid. However, if the reaction is continued further, the extent of hydroxylation decreases because of side reactions. The results of acetylation and formylation of the hydroxylated products and the grafting of vinyl monomers onto hydroborated diene polymers are also presented.
ESR studies on the effect of lignin and gases on UV photodegradation of cellulose
Authors: Nanassy A. J. , Desai R. L. 
Published: April 2003

AbstractAspen wood pulp and aspen dioxane‐lignin were irradiated by ultraviolet light under vacuum employing a special technique for uniform irradiation of the powdered samples. Examination of the effect of various gases and lignin contents of the pulps on the ESR spectra showed that the spin concentration was reduced by oxygen and lignin content, while atomic hydrogen reduced it to zero. The width and shape of the line were unaffected by oxygen, while lignin content reduced the width. A resolution for the hyperfine component of the spectrum yields an average distance of 1.3 Å between the free spin at C‐5 and the protons at C‐6 of the cellulose.
Gel permeation chromatography: The effect of pore size distribution on separation efficiency
Authors: Cooper Anthony R. , Johnson Julian F. 
Published: April 2003

AbstractColumns packed with Bio‐Glas (porous glass manufactured by Bio‐Rad Laboratories, Richmond, California) of varying porosities were made which had the same cumulative pore volume. The pore radii were equal to or larger than the mean end‐to‐end distance of the 160,000 molecular weight polystyrene molecule in carbon tetrachloride. The efficiency of these columns was studied for the elution of polystyrene Mw = 160,000 and two sharp polyisobutene fractions having Mn = 114,700 and 145,700. Elution volume was found to be independent of flow rate below a flow rate of 1 ml/min for all columns studied. Two pairs of columns with the differing cumulative pore volumes were compared, and only small differences were found in their efficiencies, as measured by the number of theoretical plates per foot. The pore size distribution is important in that it determines elution volumes and the effective separating range of the column, but it does not appear to materially affect the efficiency of the separation process.
Cellulose graft copolymers. IV. Graft copolymerization of methacrylonitrile with γ‐irradiated cellulose from DMSO–, acetone–, and methanol–water systems
Authors: Mares Trinidad , Hinojosa Oscar , Nakamura Yoshio , Arthur Jett C. 
Published: April 2003

AbstractMethacrylonitrile was graft‐copolymerized from DMSO–, acetone–, and methanol–water systems with γ‐irradiated, purified cotton cellulose. The relative extents of scavenging of the free radicals in the irradiated cellulose after immersion in the solvents for 3 min at 25°C, as determined by electron spin resonance spectroscopy, were: methanol (77%) > water (70%) ≫ acetone (5%) > DMSO (0%). After immersion of irradiated cellulose in the solvents for 60 min at 25°C, the relative extents of scavenging of the radicals were: methanol, water (80–85%) > DMSO (80%) > acetone (62%). From these data, it would appear that the overall rates of diffusion of methanol and water into the fibrous macrostructure were greater than the rates of diffusion of DMSO and acetone into the structure. The relative radiochemical yields of the graft copolymerization reactions of methacrylonitrile with irradiated cellulose in the different solvents were: water ≫ DMSO > methanol ≫ acetone. The addition of water to the systems increased the yields of the reactions.
Viscoelastic properties of epoxy resin. I. Effect of prepolymer structure on viscoelastic properties
Authors: Hata Naoaki , Kumanotani Ju 
Published: April 2003

AbstractThe intermolecular cyclization reaction is investigated in highly crosslinked epoxy systems, where diepoxides with different mobilities between terminal epoxy groups were crosslinked with ethylene diamine. Based on the measured values of the Clash‐Berg 10‐sec modulus in the rubbery region, the correlation between the mobility and the cyclization reactivity of the diepoxides is discussed. The epoxide with higher mobility is found to have a higher rubbery modulus than that with lower mobility, as was expected. This is tentatively explained by the difference in the reactivity of the formation of the 11‐membered ring. Dynamic mechanical measurements were also run on a forced vibration apparatus. The higher β‐transition peak of the polymer of bisphenol‐A diglycidyl ether was interpreted in terms of its higher free volume as well as lower density and lower glassy modulus. The higher modulus in the glassy region of ethylene glycol diglycidyl ether–ethylenediamine was explained on the basis of hydrogen bonding.
Energy absorption in polymeric foams. II. Prediction of impact behavior from instron data for foams with rate‐dependent modulus
Authors: Schwaber David M. , Meinecke Eberhard A. 
Published: April 2003

AbstractImpact behavior can be predicted for rate‐dependent foams from constant rate of strain response. The response must be factorized into a rate‐dependent modulus function and a strain‐dependent function. In this way the rate‐dependent modulus can vary throughout the impact as the velocity of the impacting object decreases.
Starch graft polymers. I. Graft Co‐ and terpolymers of starch with 2‐hydroxy‐3‐methacryloyloxypropyl‐trimethylammonium chloride and acrylamide: Preparation and evaluation as silica depressants
Authors: Jones Duane A. , Jordan Wesley A. 
Published: April 2003

AbstractThe title monomers have been grafted onto wheat starch by γ‐radiation‐induced polymerization in water providing three graft polymers containing poly[2‐hydroxy‐3‐methacryloyloxypropyltrimethylammonium chloride (I)] and two graft polymers containing poly[I and acrylamide (II)]. Characterization is discussed together with their utility as silica depressants in flotation‐beneficiation of siliceous ores. Results are provided to illustrate that a starch graft copolymer containing 15% poly(I) graft and a graft terpolymer containing 30% poly(I, II) in the ratio 1:2 are effective as selective depressants for silica in flotation‐beneficiation of Florida pebble phosphate ore using special flotation conditions.
The gel permeation chromatography of phenolic compounds
Authors: Yoshikawa T. , Kimura K. , Fujimura S. 
Published: April 2003

AbstractGel permeation chromatography, using polystyrene gel and tetrahydrofuran as solvent, has been applied to hydroxybenzophenones, esters of salicylic acid, alkylphenols, alkylated methylenediphenols, and phenol–formaldehyde condensation products. The difference between the calculated molecular volume of these phenolic compounds and that obtained by actual determination with GPC has been ascribed to tetrahydrofuran solvation of the phenolic hydroxyl group. Furthermore, it has become clear that THF solvation is affected by the steric hindrance of ortho‐substituted phenol and by inactivation of the phenolic hydroxyl group resulting from internal hydrogen bonding.
Effects of monomer impurities on the emulsion polymerization of chloroprene and properties of polychloroprene. IV. Effect of 1‐chloro‐1,3‐butadiene
Authors: Sufčák Miloslav 
Published: April 2003

AbstractThe influence of small amounts of 1‐chloro‐1,3‐butadiene on the kinetics of the emulsion polymerization of 2‐chloro‐1,3‐butadiene and on properties of the resulting polychloroprene has been studied. Some changes in the properties of the chloroprene polymers were observed at 1‐chloro‐1,3‐butadiene concentrations in monomer as relatively high as about 5%. Polymer prepared in the presence of 5% 1‐chloro‐1,3‐butadiene had decreased tensile strength, and also its crystallization tendency was somewhat lowered. At 1‐chloro‐1,3‐butadiene concentrations near 1% or higher, the polychloroprene obtained had worsened thermo‐oxidation stability which resulted in crosslinking during aging. The kinetics of emulsion polymerization of chloroprene are not influenced by 1‐chloro‐1,3‐butadiene up to 5%.
Effects of monomer impurities on the emulsion polymerization of chloroprene and properties of polychloroprene. V. Effect of 1,3‐dichloro‐2‐butene
Authors: Sufčák Miloslav 
Published: April 2003

AbstractThe emulsion polymerization of chloroprene in the presence of 1,3‐dichloro‐2‐butene in various concentrations up to 5% was studied. In contrast to all other common chloroprene impurities, no influence of this compound on the kinetics of chloroprene polymerization and the properties of polychloroprene was found. 1,3‐Dichloro‐2‐butene does not cause polymer chain transfer and it is not able to copolymerize with chloroprene under the given polymerization conditions.
The graft photopolymerization of acrylates and methacrylates on wool in dimethyl sulfoxide
Authors: Needles Howard L. 
Published: April 2003

AbstractIrradiation of wool by short‐wavelength ultraviolet light in the presence of acrylate or methacrylate esters in dimethyl sulfoxide causes intermediate grafts (2%–10%) of polymer on the surface of the wool. The amount of grafting and homopolymerization and the evenness and regularity of photografted polymer are dependent upon the monomer used. With methyl acrylate, the reaction time, monomer concentration, and introduction of water as cosolvent affect the degree of fiber grafting and the amount and molecular weight of accompanying homopolymer. Polymers grafted onto wool by this technique change the tensile properties and the water desorption characteristics of the wool.
Measurement of the rheological properties of polymer melts with slit rheometer. II. Blend systems
Authors: Han Chang Dae 
Published: April 2003

AbstractA slit rheometer described in part I of this series was used for characterizing two blend systems by their viscous and elastic properties in the molten state. The blend systems chosen for study were blends of two high‐density polyethylenes having widely different molecular weight distributions and blends of polystyrene and polypropylene which are incompatible in the molten state. The present study shows that blends of two high‐density polyethylenes and blends of polystyrene with polypropylene exhibit a minimum in melt viscosity and a maximum and minimum in melt elasticity (in terms of “exit pressure”) at certain blending ratios. These results confirm the author's earlier findings, which were obtained with a capillary rheometer.
Measurement of the rheological properties of polymer melts with slit rheometer. III. Two‐phase systems—high‐impact polystyrene and ABS resin
Authors: Han Chang Dae 
Published: April 2003

AbstractMeasurements were made of the rheological properties of commercially available rubber‐reinforced two‐phase polymer systems. The polymers chosen for study were two high‐impact polystyrenes (Union Carbide Corp., TGDB9500 and TGDB2100) and an acrylonitrile–butadiene–styrene (ABS) resin (Monsanto Co., Lustran I240 Natural). For the study, a slit rheometer was used, which was described in part I of this series. The present paper, the third of this series, clearly demonstrates the usefulness of the slit rheometer for characterizing polymer systems of industrial importance by means of their viscous and elastic properties in the molten state.