bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat Conductivity of Rubber at Low Temperatures
Authors: Schallamach Adolf 
Published: February 2011

Abstract
While examining the possibilities of applying rubber in low temperature work, we were hampered by the lack of available data on its physical properties at low temperatures. We were aware of the difficulties to be expected in making accurate measurements in that temperature region, and this applied especially to the heat conductivity, in which we were particularly interested. To obtain at least an estimate of the order of magnitude, we carried out some measurements of the heat conductivity of commercial rubber (North British tire rubber) at room temperature and at the temperature of liquid air.
Synthetic Rubbers: A Review of Their Compositions, Properties, and Uses
Authors: Wood Lawrence A. 
Published: February 2011

Abstract
Synthetic rubber has been the dream of many during the century which has passed since Faraday first determined the carbon-hydrogen ratio in natural rubber, but it has completed only about a decade of commercial success. Every year of the past ten has seen an increase in the quantity produced, the number of varieties available, and the number of applications. The aims in various countries have been different, and the development has proceeded in different directions. The most active research has been carried on in Germany, Russia, and the United States. There has been relatively little collection and intercomparison of the rather limited data on the physical properties of the different varieties of synthetic rubber. Scientific articles have been largely devoted to descriptions of single varieties or to discussions of limited phases of the work with respect to one variety. The present paper represents an attempt to make a summary of the facts regarding the different varieties, an intercomparison of some of their properties, as reported in previous publications, and to present a fairly complete bibliography of the modern literature on the subject of synthetic rubber. Because of the relatively short time during which the different varieties of synthetic rubber have been available, the data concerning them have been reported almost entirely by observers in the laboratories of companies each interested in the manufacture and sale of a particular variety. In almost every case, therefore, the figures necessarily lack independent confirmation.
Surface Area and Properties of Carbon Black
Authors: Smith W. R. , Thornhill F. S. , Bray R. I. 
Published: February 2011

Abstract
The surface areas of a number of commercial carbon blacks have been determined by the low-temperature adsorption isotherm technique. Thermal decomposition and other nonimpingement type blacks possess areas of 15 to 64 M2 per gram. Channel blacks commonly employed as reinforcing agents in rubber have areas around 100 M2 per gram. Ink and color blacks range from 100 to nearly 1000 M2 per gram. The color values of these carbons increase with surface area. The relation of iodine and diphenylguanidine adsorption to surface area has also been studied. Iodine adsorption is a direct function of surface area and, with the exception of certain high-volatile blacks, may be used as a direct measure of total surface. The adsorption of diphenylguanidine depends much more strongly on the volatile content of the black rather than its total surface. While rubber reinforcement depends in a general manner on surface area, certain blacks of nearly identical surface vary widely in the properties they impart to compounded rubber. That the state of the surface is probably of equal importance is indicated by the fact that the activity of the surface, as judged by relative ease of oxidation, may vary widely in blacks of equal area.
Crystallization Phenomena in Raw Rubber
Authors: Treloar L. R. G. 
Published: February 2011

Abstract
The process of crystallization in raw rubber held at various extensions at 0° C has been studied by following the accompanying changes in double refraction and in density. From a comparison of the two sets of data, it is concluded that a very low extension produces a relatively high degree of orientation of the axes of the crystallites in the direction of the extension. From 100 per cent extension to the breaking-point, the increase in birefringence with elongation is due almost entirely to an increase in the proportion of crystalline rubber present; over this range the birefringence therefore gives a quantitative measure of the amount of crystallization. From the study of birefringence at 25° and 50° C, it appears that crystallization sets in rather rapidly at a certain intermediate elongation, and then increases continuously to the breaking-point. The observed changes in crystallization show a close correlation with plastic flow and elastic recovery phenomena. The bearing of these observations on the molecular structure of rubber and its mode of crystallization is discussed. It is estimated that the increase of density of rubber on crystallizing is not less than 3.75 per cent.
The Impregnation of Cotton Yarns with Latex
Authors: Nederveen Gvan 
Published: February 2011

Abstract
1. Thin sections of yarn impregnated with rubber can be made in a simple manner according to the modified Kronacher-Lodemann method here described; and fibers, rubber, and embedding material can be clearly distinguished. 2. Impregnation of a cord with latex in which a wetting agent is dissolved results in a far lower degree of penetration by rubber than impregnation with latex following treatment of cord with a solution of the wetting agent. 3. When the proper conditions and wetting agent are selected, bicycle tire cord previously treated with a wetting agent can be completely impregnated with latex. 4. There is a definite relation between the microscopic picture indicating the degree of penetration of rubber between fibers and the results of fatigue tests.
Bend-Brittle and Shatter Points of Rubberlike Materials
Authors: King Glenn E. 
Published: February 2011

Abstract
Within the past two years the performance of rubberlike compositions at low temperatures has become important. A number of tests have been devised to measure the loss of rubberlike properties of many of these compositions. As the temperature is lowered, the first indication of the loss of rubberlike properties is hardening of the material. As the temperature is lowered further, the material continues to stiffen and harden to a point where it becomes quite inflexible; bending or striking with a solid object then causes breaking or shattering, due to the brittleness of the material. Up to this time the temperature at which breaking occurs has been called the “brittle point” of the material, with no distinction between the temperature at which breaking occurs on bending and the temperature at which breaking occurs on striking with a sharp blow from a solid object. It would be easy to assume that the two points occur at the same temperature. Koch tested the brittle point of elastic materials by measuring the bend stress with a micrometer gauge placed in the center of the specimen that was supported at each end. By observing the distortion caused by weights, the elastic modulus could be measured to the breaking point, which occurred at a definite temperature. This bend-brittle temperature was called the “high elasticity” temperature by Houwink and the “elasticity” temperature by Whitby. An apparatus was developed by the Thiokol Corporation for determining the flexibility of rubberlike materials at low temperatures. The samples are mounted between two plates and bent by turning a crank. The apparatus was designed so that the distance between the plates can be varied. The temperature of breaking was called the “brittle point”.
Evaluating Low-Temperature Stiffness and Brittle Point in Elastomers
Authors: Graves Floyd L. , Davis Arnold R. 
Published: February 2011

Abstract
The illustrations indicate some of the possibilities in our method of evaluation. The urgency of the times requires that all workers come forward with any new test methods that may be of value in developing better compounds, without consuming valuable time investigating all of the possibilities and limitations of such methods. Possibly other workers will wish to apply the methods described, in their studies on the effects of plasticizers, curing times and temperatures, reenforcing fillers, etc., in low-temperature compounding of the various new elastomers being pressed into service today.
The Effect of Petroleum Solvents. On the Cold Resistance of Synthetic Vulcanizates
Authors: Morris Ross E. , James Robert R. , Berger Emil H. , Werkenthin Theodore A. 
Published: February 2011

Abstract
It is concluded that immersion in light petroleum solvents improves the cold resistance of synthetic vulcanizates, and that the greater is the aromatic eontent, i.e., the lower the aniline point, of the solvent, the greater will be this improvement.
The Course of Autoöxidation Reactions in Polyisoprene and Allied Compounds. III. The Oxidation of Rubber in the Presence of Acetic Acid or Acetic Anhydride
Authors: Bloomfield George F. 
Published: February 2011

Abstract
Oxidation of rubber by oxygen in the presence of acetic anhydride leads to formation of highly oxygenated products containing a considerable proportion of acetoxyl groups. The residual unsaturation of the products of highest acetoxyl content, taken in conjunction with other analytical characteristics, indicates that three, rather than two, acetoxyl groups normally combine with each isoprene unit attacked. Although the bulk of the oxygen introduced is present in the form of acetoxyl groups, a portion occurs as carboxyl and carbonyl groups; also, whenever acetic acid is used (partly or wholly) in place of acetic anhydride, some free hydroxyl groups appear in the oxidized rubber. The proportions of carboxyl and carbonyl groups observed can be correlated satisfactorily with the extent of chain-scission occurring during the oxidation, the groups in question forming the new ends of the severed molecules. Hydrolysis of the acetylated products yields hydroxy acids, which readily undergo lactonic elimination of water. Acetic anhydride and acetic acid can clearly act as auxiliary reagents in autoöxidation reactions, and the detailed results obtained with rubber can be best accounted for on the basis of α-methylene peroxidation, followed by decay reactions involving incorporation of the auxiliary reagent as well as oxidative attack at the double bonds of the rubber.
Structure of Copolymers of Isobutylene and Isoprene
Authors: Rehner John 
Published: February 2011

Abstract
By means of ozone degradation experiments it has been shown that the isoprene units in copolymers of isoprene and isobutylene unite in the 1,4 positions. This conclusion is based on negative evidence. Since no evidence was found that would indicate a tendency for the isoprene units to occur in sequences, it is concluded that one isoprene unit cannot exert any directing influence on another, as far as their relative positions along the polymer chain are concerned. The existence of such an influence would necessitate the assumption of unprecedented long-range forces. Hence, the isoprene units must enter the chain in a random manner.
Effect of Diameter and Surface Area of Carbon Black Particles on Certain Properties of Rubber Compounds
Authors: Parkinson D. 
Published: February 2011

Abstract
Carbon blacks can be grouped into different classes according to the way in which their fineness of division relates to different properties in rubber. Within any one class the principal properties vary in a regular manner with particle size. The normal class consists of the furnace carbons, Kosmos (Dixie)-40, Statex, the rubber-grade impingement carbons, and possibly, the color-grade impingement carbons. The subnormal classes consist of thermal carbons and acetylene and lamp blacks. Irrespective of the above classification, the properties which depend more on fineness of division than on other factors are rebound resilience, abrasion resistance, tensile strength and tear resistance. The lower limit of particle diameter for best tensile strength and tear resistance appears to be higher than that for abrasion resistance. B.S.I, hardness and electrical conductivity are properties which depend at least as much on other factors as on particle size. Stiffness (modulus) depends more on other factors than on particle size. Factors modifying the effects of particle size (or specific surface) include the presence of carbon-carbon structures and a reduction in strength of bond in rubber-carbon structures. Carbon black is thought to exist in rubber in four states: agglomerated, flocculated, dispersed, and bonded to the rubber molecules (the reënforcing fraction). Abrasion resistance is regarded as providing the only reliable measure of reënforcement.
Latex Compounding of GR-S
Authors: O'Connor H. F. , Sweitzer C. W. 
Published: February 2011

Abstract
The more important findings in this study can be summarized as follows. (1) A satisfactory technique has been worked out for compounding GR-S in latex form, either with carbon alone or with carbon plus the other compounding ingredients. (2) Latex compounding of GR-S results in notable improvements in stress-strain properties. (3) Latex compounding of GR-S results in outstanding improvements in heat resistance properties, without any loss in rebound. (4) Latex compounding of GR-S results in lower modulus, higher elongation and higher subpermanent set. The increased set is significant, since it is accompanied by maintained rebound. Besides giving improved quality, latex compounding offers practical advantages and possibilities. These are listed below: (1) Latex compounding makes possible a reduction in the total milling time. This saving amounts to at least 10 per cent for carbon latex compounds and up to 50 per cent for complete latex compounds. The mixing time normally required in the Banbury is certainly not required. (2) Latex compounding makes possible cooler handling of the GR-S. Since the carbon is added to the latex at room temperature, no high temperatures are involved during its incorporation as in Banbury mixing. (3) Latex compounding makes possible cleaner handling of carbon, since it is added to the latex and is, therefore, mixed in the rubber before milling. If desired, the handling of carbon black could thus be transferred in toto to the polymer plants. This offers some interesting possibilities. (4) Latex compounding to the black crumb stage, followed by sheeting and baling, should provide a convenient and economical means for shipping black, particularly for transoceanic deliveries. There would also be important savings in containers. (5) The black latex crumb may provide a convenient form of compounded GR-S for extrusion and related operations.
Stress-Strain Data for Vulcanized Rubber under Various Types of Deformation
Authors: Treloar L. R. G. 
Published: February 2011

Abstract
Stress-strain data are given for two types of vulcanized rubber: (1) an 8% S rubber, and (2) a latex rubber. The types of deformation studied were simple elongation, 2-dimensional extension (or compression), pure shear, and combined elongation and shear. Comparison with the theoretical relations based on the molecular-network model shows the agreement to be good for the 2-dimensional extension, but less good for simple elongation and shear. The effect of combined elongation and shear is satisfactorily accounted for. It is concluded that the theory provides a satisfactory explanation of rubberlike elasticity, and forms a useful basis for the description of the mechanical properties of rubber subjected to large deformations of any type.
Pseudo-Plastic Phenomena with Vulcanized Rubber
Authors: Wildschut A. J. 
Published: February 2011

Abstract
It is shown that plastic flow and relaxation of vulcanized natural rubber follow a logarithmic course with time. As a result, it is possible to define rate of flow as the ratio of flow at constant tension to the logarithm of the time, and rate of relaxation as the ratio of the decline in tension at constant elongation to the logarithm of the time. A study of tension-rate of flow diagrams at different temperatures has shown that, at room temperature, a considerable part of the total flow measured is reversible and therefore must be considered as pseudo-flow. This pseudo-flow is caused by a retardation in crystallization, and diminishes with increase in temperature. As a result, with increasing temperature, the total rate of flow passes through a minimum. An analogous situation occurs with the phenomenon of relaxation.
Theory of Filler Reenforcement in Natural and Synthetic Rubber. The Stresses in and about the Particles
Authors: Rehner John 
Published: February 2011

Abstract
An attempt is made to develop a general theory of filler reënforcement by determining the stresses occurring in and about a spherical particle imbedded in a rubberlike medium subjected to an applied tension. For a system containing a single particle rigidly attached to the adjacent medium, an application of the theory of elasticity shows that, for infinitesimal deformations, the stress components within the particle are independent of the radial distance from the origin, taken at the center of the particle. The stress components at a given point in the surrounding medium depend on the elastic constants both of the particle and of the medium, on the radius of the sphere, on the distance from the origin, and on the angle between the direction vector and the applied tension. Expressions are given for the average stresses in media containing many (independent) particles. Theoretical values of the bulk moduli of the synthetic rubbers considered in the treatment are derived from sound velocity data. Curves showing the spatial distribution of radial and shear stresses are presented for a range of values of elastic constants to be expected for different kinds of filler particles and rubberlike materials.
Derivatives of Synthetic Rubber
Authors: Endres Herbert A. 
Published: February 2011

Abstract
By processes of cyclization and chlorination, synthetic elastomers can be converted into derivatives which differ from the parent product in the following respects: 1. Higher specific gravity. 2. Higher softening point. 3. Greater hardness and rigidity. 4. Less flexibility and elongation. 5. Greater chemical resistance. 6. Lower solution-viscosity. 7. Lower moisture-vapor transfer. 8. Lower moisture absorption. 9. Less tackiness. 10. Greater solubility in polar solvents. Thus, many of the desirable features of the commercially important derivatives of natural rubber can be duplicated in synthetic products. It is, furthermore, logical to assume that the field of usefulness of synthetic derivatives will be extended by selection of the proper type of synthetic rubber for cyclization, chlorination, and hydrochlorination to bring out certain desirable characteristics which are not inherent in products made from natural rubber.
Tear Resistance. I. Mechanisms of Tearing of Natural and Synthetic Rubbers
Authors: Buist J. M. 
Published: February 2011

Abstract
(1) Comparative tests have shown the 0.02 in. nick gives the least variable tear resistances for all the rubbers tested. The error of test is higher for synthetic rubbers (±22 per cent for a single test) than for natural rubber (±12 per cent for a single test). These errors of test apply equally at temperatures of 21° C ± 2° C, 50° C, 70° C and 100° C. (2) Adequate data have shown that tear tests are analogous to tensile tests and the width of the sample should be taken into account by expressing the results as kg. per sq. cm. instead of as kg. per cm. (3) Natural rubber is superior to the synthetic rubbers, but when the depth of nick is increased to 0.20 inch it becomes inferior to Butyl and GR-S. (4) The results emphasize the poor resistance of the gum stocks of the synthetic rubbers compared with natural rubber, and this difference is accentuated at elevated temperatures. (5) Experimental results support the theory that higher tear resistance is obtained with rubbers which crystallize on stretching. (6) The mechanism of tearing is not the same for all rubbers, and it has been found that butyl rubber maintains its tear resistance at elevated temperatures due to the development of knotty tearing. Within a more limited temperature range this effect has also been found to a lesser extent with Novoplas-A. (7) The experimental results have emphasized the need for careful examination of the type of tear developed and also the requirements of accurately analyzing and defining the stress and strain distributions within the sample.
Theory of Filler Reinforcement
Authors: Guth Eugene 
Published: February 2011

Abstract
For small loadings (up to about 10 per cent volume parts) colloidal carbon-black spheres may be considered as suspended in a continuous rubber matrix. In the present paper this model is generalized for ellipsoidal (including plate-like and rodlike) filler particles, and it is extended to the computation of various properties of the suspension in terms of the properties of the matrix and of the fillers. Viscosity, Young's modulus, stress-strain curve below crystallization and dielectric constant of the suspension are derived as linear functions of the volume concentration for small, and as quadratic functions for higher loadings. The stress-strain curves for varying proportions of fillers are similar. For small loadings the tensile strength first decreases because of the stress concentrations around the carbon-black spheres when the samples are stretched. The increase in tensile strength observed for greater loadings is caused by the tendency of the carbon-black spheres to form chains and, finally, a type of network. The stiffness increases with loading up to the point where the suspension becomes a dilution of carbon black by rubber. There the tensile strength decreases too. Binding of rubber by carbon black is similar to solvation. The theoretical conclusions were checked experimentally ; in particular, the dependence of Young's modulus on concentration, the similarity of stress-strain curves, and the decrease of the tensile strength for small loadings. The theory of the elastic properties is very similar to the theory of Einstein on the viscosity of colloidal solutions and to Maxwell's and Rayleigh's theory of dielectric properties.
Theory of Filler Reìnforcement
Authors: Dewey Jane M. 
Published: February 2011

Abstract
In a recent paper, Rehner discusses the stresses in the neighborhood of a spherical filler particle in rubber. He finds that all the stresses are discontinuous at the surface of the particle. His work is based on formula derived by Sezawa and Miyazaki on the usual assumption of continuity of displacement and of the surface stresses at the spherical boundary. As the conclusions of Rehner are, therefore, inconsistent with the assumptions on which they are based, the work must contain a mathematical error at some point. A correct solution of the problem of a spherical inclusion of any rigidity in an elastic medium under simple tension has been given by Goodier. Goodier's paper gives formulas for the stresses at any point in the medium or inclusion when the medium is under simple tension. Rehner considers a number of particular cases of filler particles in an elastomer. In each case the imbedded particle is much more rigid than the surrounding medium, and Poisson's ratio of the surrounding medium is very close to 0.5. When these conditions are fulfilled the stresses are the same, to a very high degree of approximation, as if the particle were entirely rigid and the medium incompressible. From Goodier's results it follows that each stress on the surface of the particle is 5/2 the similar stress at a large distance from the particle. Filler particles in elastomers or plastics are always so much more rigid than the surrounding medium that the error introduced by considering them as entirely rigid is much less than the error introduced by the use of Hooke's law.