bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bond Strength of Tread and Breaker Stocks under Repeated Deformations
Authors: Levitin I. A. , Korablev Yu G. , Kornev A. E. , Babitskiĭ B. L. 
Published: February 2011

Abstract
As the tire industry changed over to production from synthetic rubber a new form of service failure was encountered—stripping of the tread from the breaker. This phenomenon is most noticeable where SBR rubbers are used, and also at the boundary layer of pliedup rubbers differing in composition, having different moduli and different degree of cure in the zone of contact with each other. In recent times there have been carried out a considerable number of investigations of the dynamic strength of a system of pliedup rubbers. The results show that an important influence is exerted upon the bond strength of pliedup rubbers by their flow, which governs the increase in contact area in the boundary layers, by the diffusion of the separate links of the chain molecules of one pliedup layer into the other by the degree of the pliedup rubbers, and the bonding layers between the layers of rubber. The compounding ingredients also affect the bond strength. As a result a number of technological measures were taken to increase bond strength between the components of tires on the adoption of SBR in the industry. These were directed towards increasing the surface contact between the layers, and towards improving the surface of the semifinished products before plyingup. An important effect upon the improvement of the surface properties of tires was evidenced by increased pressure in the building process, roughening of the tread and breaker, pressing of the uncured casings after building, and introducing into tire formulas accelerator groups which ensure increase in the time spent by the stocks in the viscous flow state in the initial period of vulcanization. One method of attaining higher dynamic strength in the tread-breaker system was some increase in the modulus of the breaker rubber by increaisng the amount of channel black. A recently developed formula for tread rubber with increased elasticity and for a stiff breaker noticeably reduced the failures of tires from stripping of the tread from the breaker. Nevertheless this problem still occupies the center of attention in the industry.
Thermal Expansion Measurements and Transition Temperatures, First and Second Order
Authors: Dannis Mark L. 
Published: February 2011

Abstract
When any pure material goes through a change in state, its physical properties change greatly. In each phase the physical properties are relatively constant or change slowly enough with temperature that the rate of change of a property such as volume is a constant. This rate of change of volume is the thermal expansion coefficient, (∂V/V)/∂T. The thermal expansion coefficient is almost constant, experimentally, as long as the temperature range over which measurements are made does not include a phase transition. At the transition temperature, abrupt changes in volume are found as illustrated in Figure 1. Polymeric materials often show changes in physical properties not necessarily accompanied by abrupt changes in volume, even though the expansion coefficient does change. Since the expansion coefficient changes, some change in internal structure is suspected, and the name second-order transition (Tg) has been adopted. This kind of change is roughly diagrammed in Figure 2. This latter change at the second-order transition temperature can be found in every known polymer, even though many polymers possess clear, first-order, crystalline transitions as well. Hevea rubber, for example, has a crystalline melting point of 28° C, compared to its Tg about −70°. These data are shown, copied from Boyer and Spencer, as Figure 3.
Thermoelastic Phenomena in Natural Rubber Compounds during Cyclic Deformation
Authors: Votinov M. P. , Sulzhenko L. L. , Kuvshinskiĭ E. V. 
Published: February 2011

Abstract
1. The initial stages of stretching of natural rubber gum compounds ((λ≦4.5)) and of filled compounds ((λ=1.8−4)) are characterized by liberation of heat equivalent to the work of deformation according to Equation (lb). Further deformation takes place with liberation of surplus heat caused by- crystallization of the rubber. The relation between the work of deformation and the heat effect is given by Equation (1a) 2. The beginning of crystallization and its degree at a given elongation depend on the degree of vulcanization and on the nature of the dispersed fillers. The rubbers with the highest modulus crystallize the poorest. Active fillers such as channel black promote crystallization to a greater degree than silica gel and chalk. 3. A rate of deformation of 100% per second assures adiabatic conditions without taking special measures. 4. It was determined that errors in the quantitative analysis of the process of adiabatic stretching of rubbers result from lack of knowledge of the true heat capacity of the compound and especially from inaccuracy of measurement of elongation during the relaxation cycle.
The Importance of Rheology in the Processing of Rubber. 1. Rheological Investigations of Rubber Solutions
Authors: Edelmann K. , Kolbe G. 
Published: February 2011

Abstract
Using the mastication of rubber as an example, it is shown how rheology can be utilized, even in the industrial processing of macromolecular substances, to obtain, from an easily and quickly determined flow curve, a value dependent on the weight average molecular weight, and a numerical value for the polymolecularity. Solutions of chain macromolecules with a sort of Gaussian molecular weight distribution give a symmetrical flow curve with an inflection point which, as the velocity gradient which is independent of the concentration, is a function of the average molecular weight. At the same time the slope of the linearized flow curve provides a numerical value for the polymolecularity of the material in question. In this way, even those changes in a macromolecular substance which occur during factory processing can be measured, as is the case here with masticated rubber.
The Reaction of Ozone with SBR Rubbers
Authors: Erickson E. R. , Berntsen R. A. , Hill E. L. , Kusy Paul 
Published: February 2011

Abstract
All SBR vulcanizates, when tested in a relaxed state, reacted with ozone of low concentrations to form a film of oxidized products which provided an effective barrier against further attack by gaseous ozone. SBR vulcanizates that were under stress, but which contained no effective antiozonant in their formulation, were readily attacked by ozone. The absorption of ozone appeared to begin with an initial rate of zero which was followed by rapidly increasing rates until a maximum had been reached, when ozone cracks were visible on the surface of the rubber. SBR vulcanizates that were under stress, but which contained an antiozonant, were protected from an attack by ozone to a degree that ranged from poor to excellent. The degree of protection depended (a) on the differential in the rates of reaction of the antiozonant and the rubber hydrocarbon with ozone, (b) on the initial concentration of the antiozonant on the surface of the vulcanizate which reacted with ozone to form a barrier of oxidized residues, and (c) on the rate of effusion of fresh antiozonant from within the rubber to the outer surface of the barrier. SBR vulcanizates containing a naphthenic processing oil as an extender were not so resistant to ozone as standard SBR vulcanizates. It is probable that the effectiveness of the antiozonants tested in these vulcanizates was reduced by their high solubility in the oil phase. SBR vulcanizates containing trioctyl phosphate as a plasticizer were vigorously attacked by ozone. It is possible that the gaseous ozone dissolved to some extent into the plasticizer phase, increasing the concentration of ozone in the area causing a more severe oxidation of the rubber. SBR vulcanizates that had been coated with an antiozonant by dipping the specimen several times into a solution of the antiozonant in a solvent were found to contain a higher concentration of the antioxonant directly on the surface of the vulcanizate than in the case where three parts of the antiozonant were added during vulcanization. A mechanism for the ozonization of SBR vulcanizates has been proposed which includes a possible mechanism for the protective action of antiozonants. A rate equation has been derived from this mechanism which was consistent with the experimental rate data.
Chemical Inhibition of Ozone Degradation of SBR
Authors: Kilbourne H. W. , Wilder G. R. , Van Verth J. E. , Harris J. O. , Tung C. C. 
Published: February 2011

Abstract
The standard rubber antioxidant types which are capable of imparting ozone resistance to SBR vulcanizates are summarized. The 6-ethoxy-l,2-dihydro-2,2,4-trimethylquinoline and para phenylenediamines are shown to represent the most active structures. Steric, mesomeric, and resonance effects are shown to be important in imparting high levels of antiozone activity. When electronegative groups are substituted in an active structure, antiozone effectiveness is greatly reduced. Antiozonant activity is attributed to efficient stopping of ozone-induced free radical chain reactions in the polymeric structure.
Basic Problems in the Theory of Bond Strength between the Plies of a Rubber Article
Authors: Patrikeev G. A. 
Published: February 2011

Abstract
The problem of ensuring adequate bonding strength between uniform and nonuniform layers in composite vulcanized rubber articles is particularly vital in the production of high grade multi-ply articles for heavy duty (high speeds, high dynamic loading and considerable heat build-up) and also in the production of multi-ply articles from dissimilar compounds based on synthetic rubbers of different structural type. In works practice various methods are known for the production of two-ply and multi-ply composite vulcanized rubber articles, based on plying-up in the hot state (sometimes combined with buffing of the unvulcanized parts and the use of special materials to increase the tackiness of the stocks) and also on the use of solvents and the cementing of the stocks by a cement, sometimes of several types applied in sequence. Difficult technological tasks arise in the production of composite articles with dissimilar plies based on rubbers of different chemical composition, for instance of natural and sodium butadiene (or chloroprene) or of natural (or butadiene) and butyl rubber. In spite of considerable practical successes, many of the tasks enumerated above remain unsolved, and there is hardly any great hope of success without a previous examination of a number of basic theoretical questions. A theory of strength has not been worked out even for the most simple case—the stretching of a strip of unloaded vulcanized rubber. There are many questions unstudied, the examination of which must precede the development of a theory of the strength of dissimilar plies in a multi-ply composite rubber article. Before considering the separate questions we regard it as worthwhile to formulate the general tasks of a theory, keeping within the bounds of the problem under discussion, i.e., bond strength. According to the minimum requirements, theoretical investigations ought to enable the selection of correct basic (determinant) scientific lines and to facilitate the development of rational methods of investigation, reflecting the essential aspects of the phenomenon being studied. Of course, major failures and unplanned and wasted labor are often caused by the choice of mistaken lines of investigation or are the outcome of the use of mistaken methods of testing.
Choice of Resilient Materials for Anti-Vibration Mountings
Authors: Snowdon J. C. 
Published: February 2011

Abstract
This article attempts to determine, solely from the aspect of vibration reduction, the criteria which define a good antivibration mount material. It concludes firstly that such a material should possess a high damping factor which does not increase greatly with frequency, and secondly, that it should be free from any major increase in dynamic modulus with frequency. Results of transmissibility measurements on a variety of resilient materials indicate that high damping synthetic rubbers normally possess a dynamic modulus which increases rapidly with frequency. It is shown that this modulus increase is responsible for the poor isolation afforded by these rubbers at frequencies above the resonant frequency of the mounting system, and not their inherent high damping as commonly supposed. Filled butyl rubber is an exception, affording an isolation at high frequencies not greatly inferior to that of natural rubber, yet at the same time possessing much higher damping.
Constitution and Variability of Rubber from Individual Trees
Authors: Kemp A. R. 
Published: February 2011

Abstract
A special procedure of collecting rubber latex directly from the tree by dropping it directly into alcohol to coagulate and preserve it has been described. The color, hardness, solubility in benzene or chloroform and viscosity of the soluble portion of this alcohol-coagulated rubber has been found to vary widely in the case of rubber from 24 individual trees in a Costa Rica rubber estate. While it is shown that rubber from individual trees show wide variations, the results from bulked latex and crepe are close to the average results found for the 24 trees. The results from the present investigation show that rubber direct from the tree contains soluble and insoluble fractions like those found in crepe and smoked sheet. Lower polymers in crepe and smoked sheet are also present in the latex as it emerges from the tree. It was found that some trees yielded a rubber almost completely soluble in benzene or chloroform, while in others, the soluble portion was as low as 61 per cent, with the average being 80 per cent. High viscosity of the sol and insoluble gel both lead to hard tough rubber. The alcohol coagulums varied widely in color from almost white in the ease of some trees to various shades of cream in most of the others. A new and unexpected finding was that four of the 24 trees yielded a distinctly grey mottled coagulum. This grey color apparently comes from the presence of clotted grey lutoids not apparent in the latex itself. The constitution of sol and gel rubber is discussed and data are presented on the solubility and viscosity of the solutions obtained from the gel fraction. From these data it is concluded that the difficultly soluble gel is a three dimensional network structure with either oxygen or carbon-to-carbon linkages between the polyisoprene chains.
Fine Particle Reinforcing Silicas and Silicates in Elastomers
Authors: Bachmann John H. , Sellers John W. , Wagner Melvin P. , Wolf Ralph F. 
Published: February 2011

Abstract
Reinforcement has been described as “the enhancement of one or more properties of an elastomer by the incorporation of some ingredient thus making it more suitable for a given application”. This definition gives an excellent qualitative description of the reinforcement of an elastomer, but lacks the quantitative aspects necessary to prescribe specifications for materials to be included in the present review on reinforcing siliceous fillers. The scope of the present review will therefore be defined in terms of the properties of the siliceous fillers rather than in terms of the degree of enhancement of one or many elastomer properties. Experience has shown that substantial improvement in the physical properties of vulcanizates generally cannot be expected from siliceous fillers greater than 50 millimicrons in number average particle size, or less than 50 square meters per gram in specific surface area. These specifications will be used to delineate the silicas and silicates included in the present review, a general outline of which is presented in the following paragraphs: Description of the silica and silicate fillers is made difficult by lack of established categories for these materials. To aid in their classification, a brief discussion of manufacturing methods is presented. Then, lists of commercially available products are introduced. Physical and chemical properties of commercially available reinforcing silicas and silicates are presented, based on information in current brochures obtained from manufacturers. Failure by the manufacturer to specify his methods has occasionally diminished the usefulness of published data. for example, the term average particle size is not specific as it does not state which statistical average value is intended. The lengthy treatment given testing methods constitutes a plea to define or specify test methods. The three properties of primary interest in reinforcing silicas and silicates are the particle size, the chemical nature of the surface, and the state of aggregation. A comprehensive discussion of the chemical nature of the surface is prohibitive because of the wide scope of the topic. Nevertheless, a quick survey was made of this subject with the objective of presenting adequate information to allow an interpretation of the behavior of the fillers in elastomers. The groups encountered are principally siloxane (Si—O—Si), silanol (SiOH), and reaction products of the latter with various hydrous oxides. Attention is focused on silanol groups. Their dehydration and rehydration, their chemical reactivity, and their propensity for hydrogen bonding are considered briefly to aid in understanding interactions of the fillers with elastomers and with curatives.
Elastomeric Properties of Butyl Rubber
Authors: Buckley D. J. 
Published: February 2011

Abstract
On first thought, the properties controlling the behavior of high molecular weight substances would appear to be so overwhelmingly numerous as to defy consolidation and simplification. However, upon analysis, it can be seen clearly that they all reduce to areas of consideration which make up a relatively small group. For elastomers, such a grouping might be as follows. Size Shape Order and Disorder Composition Crosslinked Network Response to Deformation Degradative Reactions This reviewer does not intend to imply that each area can be considered mutually exclusive of any of the others. There is ample evidence of considerable interaction between these areas. Moreover, it is not intended to imply that the approach to elastomeric problems is utterly simple. The complexity within any one of the areas mentioned is well known from the literature on polymers. However, it is suggested that a grouping or classification such as given here can assure a greater clarity of concept and objectivity of analysis and experiment in approaching otherwise obtuse and complicated polymer problems. As each new polymer material comes under research scrutiny in this sense, the general “laws” governing polymer behavior are clarified and extended. This is a result of the fact that each new material usually provides features which invite and encourage research, particularly where uncertainty exists. The ease of butyl type polymers will be reviewed in this sense with two purposes in mind: (1) to define and correlate the knowledge derived from butyl research which has contributed to a better understanding of the principles of polymers, and (2) to suggest (often by inference) areas where potentially fruitful research in the same direction is still possible. This review will consider butyl polymers beyond the polymerization stage. Except where necessary to develop the proposed objectives, the chemistry of polymerization will not be considered. A number of references are recommended to the reader interested in the polymerization aspects. No attempt will be made in this review to consider butyl end uses or the compounding and technological information associated therewith. Some exception to this restriction will be made when the particular property under consideration warrants it. Rather, this review will attempt to show how a development of the basic knowledge of polymer behavior can be put to use in the solution of technological problems.
Natural Latex as a Colloidal System
Authors: Verhaar G. 
Published: February 2011

Abstract
Natural rubber latex as a raw material for industry is relatively young. Although solid rubber has been known ever since the days Christopher Columbus and his men marvelled at the natives of Haiti playing with a ball made from the gum of a tree—which was in 1496—latex received little attention until the third decade of the twentieth century. By that time the rubber plantation industry had developed to such an extent that it appeared feasible to collect, preserve and transport latex on a large scale. Malaya was the first to export latex in commercial quantities in 1922, followed by Indonesia in 1926 and by Liberia in 1935. At the outbreak of World War II annual world production of latex had reached 44,000 tons but it was not until 1948 that production was back at the same level again. The last ten years have shown a rapid increase with world production reaching 168,000 tons in 1957. This would not have been possible without the application to manufacturing of scientific methods which in turn were based on an ever increasing amount of fundamental knowledge of its properties. It is well known that natural latex, as a liquid of biotic origin, may at times show considerable variations in composition and colloidal structure as the result of biotic, geotic, cilmatic and other influences. It is these differences which account for the variability in the properties of latex and rubber, a variability which is sometimes the cause of difficulties in processing these materials to a product of well defined and uniform properties. Great strides have been made over the last twenty years and it is the purpose of this review to outline the principal facts regarding natural latex as a colloidal system and to indicate the progress made in this field of research.
Diffusion of Antioxidants in Rubber
Authors: Kuzminskiĭ A. S. , Reitlinger S. A. , Shemastina E. V. 
Published: February 2011

Abstract
The study of the diffusion of polymers in order to determine the size and shape of the macromolecules in solutions has been the subject of numerous recent works. Considerably fewer studies have been devoted to the problem of the diffusion of low-molecular substances dissolved in polymers, and the existing works in this field refer principally to gas-polymer systems. It is also known that the rate of diffusion in polymers of solid and liquid low-molecular compounds governs in a number of cases the kinetics of processes of great practical importance. In particular, the kinetics of a process as important to the rubber industry as the oxidation of rubber is, to a large degree, related to the rate of diffusion of antioxidants and other soluble ingredients in the rubber. Rubber as a diffusion medium is distinguished from liquids and solid crystalline substances by certain properties which are governed by the characteristic heat movement of the macromolecules. Thus, Brün showed that Einstein's equation cannot be applied in the case of diffusion in rubber, and Barrer developed a theory of diffusion of gases in rubber, according to which the presence of an activation zone is necessary for the initial process of diffusion. The present study concerns the diffusion of certain solid antioxidants dissolved in rubber (phenyl-2-naphthylamine, dinaphthylamine, and dinaphthyl-phenylenediamine).