bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Determination of Chlorine in Polymeric Materials by Instrumental Neutron Activation Analysis
Authors: Butler J. W. , Marsh R. H. 
Published: February 2011

Abstract
A rapid non-destructive method for the determination of chlorine in polymeric materials by instrumental neutron activation analysis is presented. The analysis portion of the determination requires only twenty minutes for three samples and standards. Precision is better than five per cent relative standard deviation at levels above one per cent and sensitivity is obtainable to 0.01 per cent.
Long-Range Order of Supramolecular Structures in Amorphous Butadiene-Styrene Block Copolymers
Authors: Kämpf G. , Krömer H. , Hoffmann M. 
Published: February 2011

Abstract
The various methods for determining quantitatively the dimensions of morphological structures from electron micrographs as well as evaluation of small-angle electron and x-ray diffraction are reviewed briefly. In continuation of previous work, the types of long-range order of supramolecular structures observed in two-block butadiene-styrene (BS) copolymers of very uniform molecular structure are discussed. By phase separation, aggregates of the one type of block with uniform shapes and sizes are formed which are arranged strictly periodically in the matrix consisting of the other type of block. Apart from “lattice imperfections”, special regard is given to the formation of boundaries between regions with long-range order of domains. The macroscopic lattices observed in BS block copolymers are compared with the latticelike arrays of colloidal particles found in other systems of a completely different chemical nature.
Poly(Butadiene)/Poly(Styrene) Interpenetrating Polymer Networks
Authors: Curtius A. J. , Covitch M. J. , Thomas D. A. , Sperling L. H. 
Published: February 2011

Abstract
Interpenetrating polymer networks (IPN's) of poly (butadiene) (PB) and poly(styrene) (PS) were prepared using both random (containing 36 per cent cis, 55 per cent trans, and 9 per cent 1,2 vinyl) PB and high-cis PB. For both series, a wide range of PB/PS compositions were synthesized. Using samples stained with osmium tetroxide, electron microscopical studies revealed an irregular cellular structure of a few hundred A˚ngstrom diameter with the first component, PB, making up the cell walls. The size of the cells was found to depend on the PB crosslink density for the random materials. Modulus-temperature data revealed two distinct glass transitions, confirming the finding of two phases by microscopy. However, the transition temperature and transition slope varied with composition, and with the microstructure of the poly (butadiene), giving evidence of significant molecular mixing. Stress-strain data on the IPN's showed that materials rich in PB behave like self-reinforced elastomers. Charpy impact resistance experiments on materials rich in PS indicated values of 5 ft-lb/in. of notch, which compares well with graft-type polyblends of similar PB/PS composition. The results were interpreted in the light of the recent theoretical work of Bragaw, who considered the importance of the distances between domain boundaries with respect to crack acceleration mechanics. Although the IPN's considered herein exhibited somewhat less than the predicted optimum phase dimensions, the arrangement of the domains is different from ordinary impact resistant plastics.
Structure and Properties of Vulcanized Rubbers from Oligomers
Authors: Lykin A. S. , Sbytov Yu G. , Tunkel I. M. 
Published: February 2011

Abstract
Structural parameters of the vulcanization network of oligomer rubber compounds depend to a much greater degree on the extent of crosslinking than those for rubber compounds based on conventional rubbers. A condition necessary for obtaining oligomer rubber compounds exhibiting a good balance of properties is the maximum possible extent of crosslinking which is determined by the maximum degree of oligomer and crosslinking agent functionalities and the equimolar ratio of their reactive groups.
Aspects of the Relaxation of the Elastic Deformation of a Polymer at High Temperature in a Mold
Authors: Stepanov Yu N. 
Published: February 2011

Abstract
Upon storage of deformed mixes at controlled temperature the relaxation of elastic deformation in most cases occurs at the same time as crosslinking. The segmental mobility of the chains of the rubber disappears rapidly with the formation of crosslinks. This indicates the possibility of obtaining vulcanizates with different shapes of macromolecules.
Properties of Poly(Dimethylsiloxane) Networks Prepared in Solution, and their Use in Evaluating the Theories of Rubberlike Elasticity
Authors: Johnson R. M. , Mark J. E. 
Published: February 2011

Abstract
Poly(dimethylsiloxane) networks were prepared by γ irradiation of solutions of the polymer in cyclohexane; concentrations employed corresponded to volume fractions ν2,s of polymer ranging from 0.3 to 1.0. The moduli of these networks were obtained by stress—elongation measurements on the extracted, dried networks, and the relative degrees of crosslinking were obtained by swelling equilibrium experiments. These data were used to calculate the dependence of the modulus on the volume at which the crosslinking had been carried out. Comparison of experimental and theoretical values of this quantity lends strong support to the theory of rubberlike elasticity developed by Flory and coworkers. In addition, for samples having equal moduli, deviations from the form of the theoretical stress—elongation relationship decrease with decreasing ν2,s, with the strongest such dependence apparently occurring at small values of this volume fraction. In contrast, non-equilibrium effects exhibited by these networks also decrease with decreasing ν2,s, but the largest change is observed at large values of ν2,s. At constant ν2,s, increase in degree of crosslinking seems to increase the cited deviations from theory but to decrease nonequilibrium behavior. These additional results suggest that such deviations from theory can be, at most, only partially due to nonequilibrium effects.
Thermodynamic Interaction in Poly(Dimethylsiloxane)—Hydrocarbon Systems from Gas—Liquid Chromatography
Authors: Summers W. R. , Tewari Y. B. , Schreiber H. P. 
Published: February 2011

Abstract
Poly(dimethyl siloxane) has been used as the stationary phase in gas—liquid chromatography. Retention volumes have been used to calculate the thermodynamic interaction parameters for a series of linear and branched alkanes and aromatic hydrocarbons interacting with the polymer. Values of the χ parameter have been compared with results for the same systems obtained from equilibrium (static) vapor-absorption experiments, and found to be in excellent agreement. The successful comparison indicates the potential value of the glc route as the source of rapidly obtained thermodynamic data at infinite dilution of the volatile phase. A number of the prerequisites are established for useful application of the glc method to polymer solution thermodynamics.
Thermodynamic Interactions in Polymer Systems by Gas—Liquid Chromatography. II. Rubber—Hydrocarbons
Authors: Tewari Y. B. , Schreiber H. P. 
Published: February 2011

Abstract
The application of gas—liquid chromatography (glc) to the study of thermodynamic interactions in polymeric systems is attractive in its ability to generate data rapidly and to extend these into high polymer concentration ranges which are difficult to study by conventional methods. Several recent publications have shown that glc data can produce thermodynamically meaningful results, our most recent work showing very good agreement in a comparison of thermodynamic interaction parameters calculated from glc and equilibrium sorption data for poly(dimethylsiloxane) (PDMS) interacting with selected hydrocarbons. The demand for accuracy in thermodynamic data is considerable, if, for example, these are to be of use in resolution of varying predictions drawn from theories of solution thermodynamics. It is therefore prudent to extend the test of the rapid method's usefulness by comparing thermodynamic data calculated from conventional equilibrium sorption results and from glc data for additional polymers. The system natural rubber—hydrocarbons lends itself for such a comparison and is the subject matter of this report.
Topologically Interpenetrating Elastometric Networks
Authors: Klempner Daniel , Frisch H. L. , Frisch K. C. 
Published: February 2011

Abstract
Several partially interpenetrating polymeric networks (IPN) were made by combining chemically different linear elastomers. The polymer combinations were deposited as films from aqueous emulsions made by mixing the individual emulsions in equal proportions. The films were crosslinked to form two superimposed networks. In two cases, the networks were cleanly separated by hydrolysis of one of the component networks to demonstrate that there was no chemical interaction between the polymers. Measurement of crosslink density showed that, in most cases, partial interpenetration does occur as evidenced by an effective crosslink density of the IPN's greater than the arithmetic mean of the crosslink densities of the component networks. The swelling ratios, densities, and stress-strain properties were determined. For one of the network combinations, a poly (urethane-urea) and a poly (butadiene-acrylonitrile), a series of IPN's varying in polymer composition was made. The swelling ratios and densities are close to the arithmetic means; however, both the tensile strength and crosslink density exhibit a maximum at about 70% poly (butadiene-acrylonitrile). The maximum tensile strength is actually significantly higher than that of either of the component polymers. The elongations all approach that of the poly (urethane-urea), the more extensible material, except for compositions approaching 100% poly (butadiene-acrylonitrile), which exhibit a very low extensibility.
Vulcanization of Liquid Polydienes with Dithiols and Peroxides
Authors: Strecker R. A. H. 
Published: February 2011

Abstract
The vulcanization of polydienes with dithiols and peroxides was investigated. It has been found that liquid polybutadiene can be cured with aliphatic dithiols at temperatures below 100° C, yielding products which are comparable in mechanical properties with those obtained from carboxyl terminated liquid polybutadienes but with greatly improved stability against hydrolysis and air oxidation. Investigations of the curing mechanisms showed that with excess dithiol in respect to the peroxide the formed thiyl radicals react only with the vinyl groups to form stable products. Thus, under these conditions it is not possible to cure cis-polybutadiene and polyisoprene where only isomerization occurs. Of the two antioxidants investigated, phenyl-#x03B2;-naphthylamine does not inhibit the curing reaction whereas 2,2′ -methylene-bis(4-methyl-6-t-butyl phenol) interferes with it.
An Investigation into the High Temperature Strength and Reinforcement of Natural Rubber
Authors: Harwood J. A. C. , Payne A. R. , Whittaker R. E. 
Published: February 2011

Abstract
The failure criterion for amorphous polymers relating hysteresis at break with energy input to failure in tensile stress-strain tests was found to be obeyed only at very high or very low temperatures in natural rubber. Tensile results between about 80° C and 130° C show a high degree of scatter, and this behavior is attributed to the ability of natural rubber to crystallize at high strains. The modification of tensile properties by the addition of carbon black in natural rubber is also discussed and compared with published results from SBR. The effect of changing the degree of crosslinking on the failure properties in both dicumyl peroxide and sulfur-cured vulcanizates of natural rubber is also considered. It is found that differences in failure properties can be accounted for by the use of a crosslinking parameter from simple rubber elasticity theory in some of the failure equations.
Creep and Stress Relaxation of Natural Rubber Vulcanizates. Part I. Effect of Crosslink Density on the Rate of Creep in Different Vulcanizing Systems
Authors: Fairlie E. D. 
Published: February 2011

Abstract
The physical creep of unfilled natural rubber vulcanizates, prepared with different vulcanizing systems, has been studied. For each of the three vulcanizing systems chosen there is a strong dependence of creep rate on crosslink density, but the rates for accelerated sulfur vulcanizates are two or three times higher than those of peroxide vulcanizates of similar crosslink density. Supplementary experiments, in which the crosslink structure of sulfur vulcanizates is modified either by chemical treatment or by variations in the vulcanizing conditions, show that the nature of the crosslink itself is not a determining factor in the type of vulcanizate. Other features, such as the type and quantity of extranetwork material arising from the vulcanizing process, contribute significantly to the viscoelastic behavior of accelerated sulfur vulcanizates.
Study of Sulfur Vulcanization of Brominated Ethylene-Propylene Rubber
Authors: Dontsov A. A. , Novitskaya S. P. , Dogadkin B. A. 
Published: February 2011

Abstract
(1) It is shown that when BEPR is heated at 130–190 ° with various components of a sulfur vulcanizing system, the latter take part in nucleophilic substitution reactions with the combined bromine, and promote dehydrobromination of the polymer chains and crosslinking of the elastomer. (2) The effect of the components of the vulcanizing system on dehydrobromination is dependent on the acidity of the component, and their effect on vulcanization is dependent on the extent to which they activate the reaction of sulfur with the polymer. (3) Zinc oxide is itself a vulcanizing agent. In reacting with BEPR it forms ether crosslinks. (4) When BEPR is vulcanized by sulfur together with sulfur vulcanization accelerators and activators two types of crosslink are formed, namely strong C-C and C-O-C bonds and weaker sulfur bonds. This combination of bonds gives vulcanizates of increased strength.
Influence of Temperature on the Tensile Strength of Carbon Filled Vulcanizates
Authors: Sambrook R. W. 
Published: February 2011

Abstract
Despite undergoing a substantial reduction with increasing temperature the presence of carbon black added to the strength of both natural and styrenebutadiene rubber at temperatures up to 185° C. The magnitude of reinforcement was primarily dependent upon filler surface area although at the higher temperatures when this dependence is not so marked both high structure and particle activity appear advantageous. No theory of carbon black reinforcement can reasonably ignore the morphological characteristics of the material whose action it is attempting to explain. The concept of within aggregate voids, and occluded rubber envisaged by Medalia and used in this paper to describe the effect of fillers on rubber modulus, provides an interesting molecular meaning to the effects that have hitherto been explained on the basis of “shell” theories. Occluded rubber might reasonably be viewed as a type of shell since it undoubtedly represents a polymer zone in which molecular mobility is restricted. Furthermore the view of rubber being pulled from the interstices of an aggregate, manifestly a stress softening action, provides a source of plastic flow and mechanical hysteresis in the region of the aggregate—an apparent prerequisite for reinforcement.
How Does Rubber Slide?
Authors: Schallamach A. 
Published: February 2011

Abstract
Visual observations of contact areas between soft rubber sliders and hard tracks, and between hard sliders and soft rubber tracks, show that relative motion between the two frictional members is often only due to “waves of detachment” crossing the contact area at high speed from front to rear. Adhesion appears to be complete between these waves which are moving folds in the rubber surface, almost certainly produced by buckling. Buckling is attributed to tangential compressive stresses, predicted by a simple theory and qualitatively confirmed by experiment. The driving force for the waves of detachment is a tangential stress gradient, also theoretically predicted.
Studies on Tire Wear. I. Correlation between Laboratory Abrasion Tests and Road Tests
Authors: Satake K. , Sone T. , Hamada M. , Hayakawa K. 
Published: February 2011

Abstract
The correlation between laboratory abrasion tests and road tests were studied and the following results were obtained for SBR and BR tread compounds. 1. The Akron, the Pico and the Williams abrasion test results correlate well with the road test results, especially the Pico abrasion test results, even when formulations and polymers are varied. 2. In Williams abrasion tests, the differences among compounds are much more magnified than in the case of the road tests and they are less magnified in the order of Akron &gt; Pico. These differences might be ascribed to the different severity of each abrasion machine according to Gelinas??? theory. The severity of each abrasion test decreases in the following order: Williams abrasion ≪ Akron abrasion &gt; Pico abrasion The severity of Pico abrasion most approaches that of road tests. 3. The Akron and the Pico abrasion test results on aged samples are well correlated with the road test results as in case of the test results on samples before aged. The differences among compounds are smaller in case of the laboratory test results on aged samples than in case of the results on samples before aging, and approach those of the road test results.
Truck Tire Groove Cracking Theory and Practice
Authors: Clapson B. E. , Lake G. J. 
Published: February 2011

Abstract
The work described has aimed at clarifying the mechanism of groove cracking in tires. Basic studies of the fracture mechanics of rubber have shown that the rate of growth of a crack is independent of sample shape and type of deformation when it is expressed in terms of the available elastic energy. An empirical method is described which enables the energy to be estimated for a tire groove from measurement of the amount by which a crack opens under stress. The method also enables the strain to be determined and can, in principle, be applied to any stressed article. Using this approach and the crack growth characteristics of the tread rubber, the rate of growth of groove cracks in a tire can be predicted. Satisfactory quantitative agreement is found between observed and predicted behavior suggesting that the mechanism has been correctly identified. The work indicates relevant design factors and material properties and enables an appropriate laboratory test for groove cracking resistance to be defined.
Recent Observations on the Mechanical Properties of Polymer Networks
Authors: Thirion P. , Chasset R. 
Published: February 2011

Abstract
The influence of temperature, elongation, swelling or dilution ratio, crosslink density, nature of the polymers, and crosslinking agents on the dynamic properties, creep and relaxation of polymer networks is surveyed in the terminal region of the spectrum. Whereas the deformation does not change the relaxation kinetics in large ranges of extension, the crosslink density acts as a reduced variable apparently accelerating uniformly the viscoelastic processes beyond the glass transition. The other possible reductions ‘time-temperature’ and ‘time—swelling’ do not necessarily seem related to the variations of free volume. From the viewpoint of the explanation of the relaxation mechanisms in the terminal zone, the fact that the equilibrium of loosely crosslinked elastomers would only virtually be reached after several years at room temperature seem in better agreement with chain entanglement effects, either trapped or not by the permanent network, than with the dissociation of secondary linkages.
NMR Study of Vulcanized Rubber
Authors: Fujiwara Shizuro , Fujimoto Kunihiko 
Published: February 2011

Abstract
It is shown that NMR-linewidth measurements are useful to obtain information about the crosslink density and the average distance between the crosslinks in vulcanized rubber. Inhomogeneous structure of the rubber phase in carbon black-filled rubber is evidence and the thickness of the rubber layer on carbon black is estimated at 50 A˚.
Determination of Polymer Composition of Rubber Vulcanizates
Authors: Carlson D. W. , Ransaw H. C. , Altenau A. G. 
Published: February 2011

Abstract
Various methods exist for the quantitative determination of the polymer composition in vulcanized stocks. These methods consist of dissolving the vulcanizates in boiling o-dichlorobenzene, removal of the carbon black by filtration, and then infrared determination of the polymer. Pyrolysis of the stock followed by infrared analysis of the products has also been used. This technique had the disadvantages of requiring an analysis of products other than the original polymer or polymers. The infrared calibration based on polymers would no longer be valid. There may also be some uncertainty about changes in the relationship between the original microstructure and the pyrolysis products. Other infrared studies have been made but no quantitative measurements were reported. Recently an NMR method was published for vulcanizate analysis. The method consisted of dissolving the vulcanizate in hexachlorobutadiene, recording the NMR spectrum of the solution, and determining the total amount of butadiene, styrene, and natural rubber from the spectrum. Good results were obtained on a variety of vulcanizates. The one disadvantage of the method was that only a limited amount of microstructure data could be obtained. This was due to the lack of resolution of the 60-megacycle NMR. We have now developed a technique which allows enough of the rubber to dissolve in carbon disulfide for infrared analysis. This solution is free of carbon black. Infrared analysis provides microstructure data on the butadiene and/or isoprene portions as well as the total styrene content.
The Effect of Aging on the Reinforcing Properties of Carbon Blacks
Authors: Lezhnev N. N. , Krasilmikova M. K. , Yakuzhina K. A. , Filimonova G. D. , Nikitina O. V. 
Published: February 2011

Abstract
Carbon blacks age more in air than in a vacuum, and mostly within the first three months of exposure. During the aging process, certain changes occur in the adsorption characteristics of the blacks, such changes being brought about by oxidation, and by rearrangement of the functional groups at the surface. The disappearance of highly active adsorption centers at the surface of the blacks leads to a reduction of the tensile strength, the stress at 300% elongation, and the wear resistance of the vulcanized rubbers into which such blacks are incorporated. There is also a change in the relaxation characteristics of the rubbers.