bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of Carbon Black Type in Filled Rubber Vulcanizates
Authors: Nabors Lester G. , Studebaker Merton L. 
Published: February 2011

Abstract
A system of analysis has been described which permits determining the type of rubber grade carbon black in a vulcanizate. The carbon black is removed from the vulcanizate by vacuum pyrolysis at 850° C and its reflectance after acid washing and compression at 15,000 psi and apparent specific volume at 703 psi are determined. These measurements permit estimation of particle size and “structure.” Supplementary analyses are required for channel blacks. The procedure is most precise when the analytical values are compared with analogous data obtained from carbon blacks of known properties when removed by the same procedure from similar vulcanizates. As in all qualitative analyses, the more information which is available to the analyst, the more reliably he is able to interpret his results.
A Simple Theory of Filler Reinforcement in Elastomers Subjected to Shear
Authors: Zorll Ulrich 
Published: February 2011

Abstract
The effects of a filler in an elastomer can be described by means of a theory based on a simple model in which the filler particles are assumed to be of uniform size, of cubic shape, and dispersed in such a manner as to occupy the points of a cubic space lattice. For the case of shear deformation, simple relations can be derived for the increase in the storage modulus G′ and the loss modulus, G″ of the bulk material with an increase in filler content. Furthermore, the theory predicts the temperature shift of two points which can be easily determined experimentally: the inflection point of G′ and the maximum of G″.
Mild Stress Softening and Dynamic Properties of Rubber Vulcanizates
Authors: Voet Andries , Cook F. Russell 
Published: February 2011

Abstract
Mild, reversible stress softening of vulcanizates loaded with carbon blacks of widely different structures and reinforcing characteristics was investigated by means of a novel electronic variable shear amplitude dynamic tester. The instrument yields low frequency dynamic data for vulcanizates in the range of double strain amplitudes of 3×10−5 to 1.0, covering nearly five decades. Mild reversible stress softening (up to 100 per cent amplitude) in a variety of vulcanizates investigated is caused by a reversible thixotropic breakdown of transient carbon chains, which contribute to reinforcement by an energy dissipating mechanism. Persistent, “fused” carbon chains contribute to reinforcement by their beneficial influence on the crosslink density of the vulcanizate. Elastomer and carbon chains respond independently to stress.
Crystallization in Stretched Polymer Networks. II. trans-Polyisoprene
Authors: Gent A. N. 
Published: February 2011

Abstract
Measurements are described of the rates of crystallization and crystal melting temperatures in stretched test pieces of trans-polyisoprene, crosslinked to various degrees. The increases in rate with extension are attributed to the corresponding increases in melting temperature and hence degree of supercooling. The rise in the melting temperature of both the α and β crystal forms is found to be in satisfactory agreement with Flory's treatment of oriented crystallization. Changes in tensile stress are also generally in accord with the formation of oriented crystallites. For the more lightly crosslinked materials, a pronounced rise in tensile stress occurred during the later stages of crystallization, at extensions below about 100 per cent. Reasons are given for attributing this phenomenon primarily to the relatively large contraction in volume on crystallization, rather than to the formation of folded-chain crystallites.
Polypropylene Oxide. IV. Preparation and Properties of Polyether Networks
Authors: Allen G. , Crossley H. G. 
Published: February 2011

Abstract
Stable vulcanizates of copolymers of propylene oxide and butadiene monoxide have been prepared and some physical properties studied. The cohesive energy density of a copolymer containing 84 per cent propylene oxide is determined from swelling measurements to be 83 cal cm−. The dynamic properties of the copolymer are similar to those of natural rubber. From a thermodynamic point of view the copolymer is more ideal in its rubbery behavior than natural rubber.
Cold Flow in High Impact Polystyrene
Authors: Arends C. B. 
Published: February 2011

Abstract
Eyring's theory of viscous flow has been applied to some mechanical properties of rubber modified polystyrenes. Yield strengths as a function of orientation, temperature, and rate of strain have been shown to be consistent with the theory. The temperature of transition from ductile to brittle fracture as a function of orientation has also been measured and found to be consistent with theoretical predictions.
Extraction of Admixed Polymers from Natural Rubber Vulcanizates
Authors: Cooper W. , Smith R. K. 
Published: February 2011

Abstract
Extraction by solvent of admixed poly(methyl methacrylate) or polystyrene from natural rubber vulcanizates is dependent on the crosslink density, the solvent, the molecular weight of the polymer, and the size of sample extracted. High molecular weight polymer is extracted very slowly, and in some cases several weeks of continuous extraction have been found necessary. The rate of extraction is increased, as would be expected, by solvents which swell the rubber strongly, and by increase in temperature of extraction. In some cases the vulcanization procedure degrades the polymer, while in others there is a possibility of cocrosslinking the rubber and polymer. Graft copolymers from rubber and methyl methacrylate or styrene possess similar characteristics when vulcanized. In consequence, analysis of the content of free homopolymer is subject to considerable uncertainty. In the analysis of these rubber and polystyrene mixtures by ozonolysis, polystyrene was found to be very susceptible to attack by ozone.
Chain Density in Rubber Networks
Authors: Bobear W. J. 
Published: February 2011

Abstract
Though difficult to prove from experimental data, the concept that network chain density is reflected in the Mooney-Rivlin C1 parameter has received fairly wide acceptance. In the present work, experimental stress strain measurements on natural rubber are shown to be consistent with the idea that the network chain density is directly related to the sum of the Mooney-Rivlin constants, C1 and C2; rather than to the C1 parameter only. The determination of elastically effective chain densities in polydimethylsiloxane networks is also discussed. A relationship is obtained for concentration dependence of the polydimethylsiloxane-toluene interaction parameter. The results are used to study the cure of polydimethylmethylvinylsiloxanes with “vinyl specific” peroxides. Experimental data favor the proposal that a trimethylene crosslink is formed by the reaction of a methyl group with a vinyl group through a free radical mechanism.
Migration of Extender Oil in Natural and Synthetic Rubber
Authors: Lewis James E. , Deviney Marvin L. 
Published: February 2011

Abstract
The migration of oil, and in particular, the migration of extender oils in rubber is being studied through the use of radioactive isotopes. Techniques have been developed for uniform carbon-14 labelling of the aromatic-polar fractions of extender oils by Friedel-Crafts reaction and for the uniform labelling of the paraffinic fraction by methylene diradicals generated during photolysis of diazomethane-C14. These techniques formed the basis for a comparative study of the diffusion rates of aromatic and polar, and paraffinic, fractions of a highly aromatic and a paraffinic extender oil in several rubbers which represent a wide range in type of polymeric structure. Faster diffusion rates of both aromatic and polar, and paraffinic fractions, were observed in polybutadiene and natural rubber than in SBR, EPT, and polychloroprene. In most rubbers, paraffinic materials migrated appreciably faster than aromatic and polar fractions. Experiments using Firestone flex blocks indicated that oil migration rates are higher under simulated working conditions than when the sample is subjected to heat treatment alone. Diffusion coefficients for the migrating fractions were calculated from an appropriate solution of the basic differential equation of diffusion using modern computer techniques. The methods which have been developed are suitable for fundamental studies to gain more insight into the mechanisms of diffusion. These experimental methods are also suitable for use in practical studies of oil migration under actual or simulated working and environmental conditions. Ultimately sufficient information should be obtained to permit an accurate prediction of the performance of an extender oil in selected rubbers on the basis of the physical properties of the oil and a quantitative knowledge of the major molecular types present in the oil.
Linear Elastomeric Block Polymers
Authors: Zelinski Robert , Childers C. W. 
Published: February 2011

Abstract
Polymer molecules containing chemically dissimilar segments have been investigated for many years. Their synthesis and characterization are challenging, and it is evident that their properties are often unusual and useful as witnessed by several books and reviews published on block and graft polymers. In this article we intend to review parts of this rapidly expanding area of polymer research of particular interest in rubber chemistry and technology, namely linear elastomeric block polymers. Sometimes the literature specifies the elastomeric nature of the products, on other occasions it does not. We have arbitrarily included those monomer combinations in which at least one monomer is known to form rubbery homopolymer. Urethan elastomers have been excluded because they have been extensively described elsewhere. In the broadest sense, block polymers are molecules in which two or more chemically dissimilar segments are joined end to end, a feature which distinguishes them from graft polymers. Each segment or block is usually a long sequence of units of a single monomer (A or B or C, etc.), but it may also be a long sequence of randomly copolymerized units (A plus B or C, etc.). Both types are known.
Oxidative Aging of Natural Rubber
Authors: Cunneen J. I. 
Published: February 2011

Abstract
In the last few years several reviews and books have been published on the aging of elastomers, but the overall view which they present of the oxidation of natural rubber and its vulcanizates still contains many puzzling features. Two of these are the variation of antioxidant efficiency in different types of vulcanizate, and the extent of the involvement of crosslink scission in the overall degradation process in sulfurated vulcanizates. Sometimes apparent contradictions have arisen from a failure to appreciate that aging of natural rubber vulcanizates depends primarily on four factors; the purity and type of rubber, the presence of additives, the type and extent of vulcanization, and the purification (if any) after cure. In many cases direct comparisons have been attempted without due consideration being given to all these factors, leading inevitably to some confusion. Recent work on the structure of vulcanizates has enabled the NRPRA to embark on a program of aging studies with vulcanizates of carefully controlled structure and complexity, which has already led to a better understanding of the processes involved in vulcanizate degradation. This review will attempt to elucidate the present state of knowledge, and will therefore be largely concerned with recent work at NRPRA, and its relation to previous studies. The review is divided into two main parts, they are: the effect of vulcanizate structure on aging, and the chemistry of oxidative scission reactions. Before attempting to rationalize the effect of vulcanizate structure on aging, structural characteristics of the most important types of vulcanizate are briefly discussed.
Study of Polymer Blends. II. Blending SBR Varying in Styrene Content with Polybutadiene
Authors: Fujimoto K. , Yoshimura N. 
Published: February 2011

Abstract
For this study of effect of SBR styrene content on blends of SBR and BR, polymer solubility was investigated by phase contrast microscopy, dielectric loss, and dynamic characteristics. Physical properties of blended rubber were also measured.
Observations on Fracture of Viscoelastic Bodies
Authors: Halpin J. C. , Polley H. W. 
Published: February 2011

Abstract
The Bueche-Halpin theory for the fracture of viscoelastic bodies is extended to predict the statistical variability of rupture data for both uniform and non-uniform excitation histories. The concept of cumulative damage is examined in light of some critical experimentation. It is shown that the geometry of the distribution is a sensitive “functional” of the excitation history and that the solution of this problem is the key step in the development of a general theory for fatigue.
Elastic Behavior, Birefringence, and Swelling of Amorphous Polyethylene Networks
Authors: Gent A. N. , Vickroy V. V. 
Published: February 2011

Abstract
Polyethylene networks were prepared by γ-irradiation of linear polyethylene, both molten and crystalline. Elastic and. photoelastic properties of the networks were studied at high temperatures, i.e., in the molten state. Equilibrium swelling was also measured in several solvents. Values of the crosslinking efficiency G of γ-radiation, the molecular weight Me between entanglements, the optical anisotropy α of the equivalent random link, and the polymer-solvent interaction parameter μ are deduced. Samples prepared by irradiation in the amorphous state showed markedly nongaussian elastic behavior. The presence of a large nongaussian term in the optical anisotropy is also deduced. The value of α obtained for swollen samples, which showed substantially gaussian elastic behavior, was 3.9×10−24, about one half of that obtained for dry samples. It corresponds to an equivalent random link of only about 5 CH2 units, on the basis of Denbigh's values for bond polarizabilities. The samples prepared by irradiation in the crystalline state also showed lower values for α, depending on the degree of crosslinking. This is attributed to the nonrandom chain configurations prevailing at the time of crosslinking. The same samples were found to show more nearly gaussian elastic behavior, which is attributed to the same cause.
Radiofrequency Heating of Rubber and Carbon Black Mixes
Authors: Langton N. H. 
Published: February 2011

Abstract
In conclusion, the simple model of a uniform array of spherical conducting particles of negligible size, when modified for a random distribution, enables predictions as to the maximum permissible loading of carbon black in a rubber/black mix that can be heated by dielectric heating without breakdown. The theory agrees qualitatively with the results of Gehman's theory of random filler dispersions. It is not possible to compare values given by the theory with experimental results, because there is no reliable data giving breakdown voltage figures for rubber/black mixes of known dispersion. However predictions given by the theory agree qualitatively with experiments.
Molecular Weight Effects in Adsorption of Rubbers on Carbon Black
Authors: Kraus Gerard , Gruver J. T. 
Published: February 2011

Abstract
The molecular weight dependence of the adsorption of polybutadiene on carbon black from a poor solvent, n-heptane, and bulk, i.e., the phenomenon of “bound rubber”, was investigated. For narrow distribution polymers the adsorption is proportional to Mn, where n = 0.14 for adsorption from n-heptane solution; n = 0.5 for adsorption from bulk. Anomalously low solution adsorption was observed for polymers of very high molecular weight (&gt; 500,000). This is ascribed to a sieve effect by aggregates of carbon black particles which cannot be penetrated by the large molecular coils. In high structure blacks, which pack more loosely, and in large particle blacks, which form larger interstices between particles, onset of anomalous adsorption is shifted toward higher molecular weights.
SBR and BR Tread Performance as a Function of Carbon Black Properties
Authors: Micek E. , Lyon F. , Hess W. M. 
Published: February 2011

Abstract
All commercial tread grade carbon blacks, may be classified on the basis of electron microscope surface area and oil absorption. Similar industry wide grade classification on the basis of iodine number, tinting strength and oil absorption is considerably less reliable. However, among the blacks of individual carbon black suppliers, reasonably good classification of the tread grades is possible on the basis of these latter three carbon properties.
Normal Freezing of Solutions of Isobutylene Polymers and Copolymers
Authors: Dole-Robbe Jeanpierre 
Published: February 2011

Abstract
Normal freezing of dilute solutions of polyisobutylene in cyclohexane was examined. Variation in distribution coefficient with freezing rate and molecular weight of the solute was observed, as well as establishment of a gradient for molecular weight in the frozen charge. Polyisobutylene-polystyrene or poly (methyl methacrylate) copolymers were likewise frozen, in benzene solution.
Curative Diffusion between Dissimilar Elastomers and its Influence on Adhesion
Authors: Gardiner J. Brooke 
Published: February 2011

Abstract
The diffusion of common curatives, such as sulfur, TMTD, MBTS, and DOTG, at vulcanizing temperatures between butyl, chlorobutyl, or EPDM and natural rubber, SBR, BR, or neoprene has been studied by light microscopy and attentuated total reflectance infrared. Diffusion occurs with all these curatives. Curative solubility in rubber, which affects diffusion, has been measured at various temperatures. Prom this, distribution coefficients have been calculated by considering the system as a liquid-liquid extraction. These coefficients range between 0.7 and 10. Diffusion coefficients have been obtained, and the energy of activation for diffusion has been calculated. The effect of diffusion upon adhesion between rubbers is also discussed.
The Chemistry of Sulfur Curing. III. Effects of Zinc Oxide on the Mechanism of the Reaction of Cyclohexene with Sulfur
Authors: Wolfe James R. , Pugh Thomas L. , Killian A. Stanley 
Published: February 2011

Abstract
Reaction of cyclohexene and sulfur at 140° followed by lithium aluminum hydride reduction of the polysulfide products results in the formation of cyclohexanethiol, 2-cyclohexene-1-thiol, cis- and trans-1, 2-cyclohexanedithiol, and cyclohexyl sulfide. If zinc oxide is present during the reaction, trans-1, 2-cyclohexanedithiol is the major product. In the absence of zinc oxide, cis-1, 2-cyclohexanedithiol is the major product. It is postulated that in the absence of zinc oxide the reaction proceeds via a free radical chain involving polysulfenyl radicals accompanied by a secondary polar addition reaction of hydrosulfide products with cyclohexene. Zinc oxide when present is postulated to initiate an ionic chain reaction which, due to its greater velocity, dominates the radical chain reaction.
Elastomer Rheology and Processing
Authors: White James Lindsay 
Published: February 2011

Abstract
The handling of raw elastomers in processing and fabricating equipment has been an important industrial operation for 150 years. It was an integral part of a sizable industry several decades before the molecular structure of rubber itself was realized or complex deformation-induced phase transitions and mechanochemical degradation reactions were thought to occur in these materials during processing. The rubber industry was already established when the classical organic chemical industries came into being and predates its sister plastics and synthetic fiber industries by three quarters of a century or more. It is ironic and rather unfortunate that the scientific study of rubber processing operations has been generally neglected while the basic processes of newer and sometimes smaller industries have received considerable attention, and even found their way into university engineering curricula. This is undoubtedly due to pecularities of the industry. Considerable amounts of fillers, oils, and other ingredients are added to rubber, which allow the rubber technologist to resolve processing problems through changing the (secret) composition of compounds rather than by scientific analysis. Certainly another reason is the polymer synthesis orientation (to some extent justified) of rubber industry research. During the years of the Rubber Reserve Program, when research was government supported and widely and openly publicized, there were considerable advances in knowledge of free radical homo-and copolymerization in solution and emulsion, but relatively little progress was made in the understanding of rubber rheology and processing.
Elastomers and their Adhesion
Authors: Crocker Guy J. 
Published: February 2011

Abstract
The last general review of elastomeric adhesion and adhesives appeared in this journal eight years ago. At that time an attempt was made, at least in a limited way, to develop the subject from its scientific beginnings and to present a fairly broad and connected picture. The objective of the present review will be more modest, an up-dating only. Much of what was said in the earlier review remains pertinent and relevant today, and no attempt will be made to restate such material in detail, although summarization of current status will be attempted. On the theoretical side, emphasis will be on those studies which have modified earlier views, disproved some theories or strongly confirmed others, or unified previously disconnected observations. On the technological side, emphasis will be on new applications for adhesives, new adhesive raw materials and techniques and the increased scope they offer, and new materials to be bonded with the problems and challenges they engender. For some time, growth in adhesives has consistently outstripped the general economy, and elastomeric adhesives have more than held their own as compared with other types. Adhesive production in 1965 was estimated at 3.2 billion solid pounds. Probably at least 10% of this could be considered elastomeric, and, if expressed in dollar value, would be a much greater proportion. A recent estimate of growth rate for adhesives and sealants was 10% per year, approximately twice that of the dry rubber industry. There is every reason to believe that this trend will continue in the foreseeable future as the former psychological resistance to “gluing” as opposed to rivets, bolts, nails, and welds fast disappears. Accelerating economic growth has stimulated technical advances, and the reverse, and this is reflected in a burgeoning literature.
Softening of Rubber by Deformation
Authors: Mullins L. 
Published: February 2011

Abstract
It has been known for many years that deformation results in softening of rubber and that the initial stress-strain curve determined during the first deformation is unique and cannot be retraced. Further the effect of repeated deformation is to cause rubber asymptotically to approach a steady state with a constant or equilibrium stress-strain curve. Softening in this way occurs in vulcanizates either with or without fillers although the effect appears to be much more pronounced in vulcanizates containing high proportions of reinforcing fillers. After the hardness test the simple extension stress-strain test is the test most widely used by rubber technologists. The conventional stress-strain curve is obtained on samples which have not been previously deformed and for design purpose the unique value of stiffness given by this curve may be of little significance. Thus it appears that the values of stress—strain properties determined after “conditioning” cycles of deformation would be of more practical use than the unique value obtained in the conventional test. In recent years much interest has been shown in the factors responsible for this softening behavior particularly in regard to the implications of the loss of the stiffening action of reinforcing fillers on the mechanism of reinforcement.