bluuebunny/crossref_metadata_2025_split huggingface dataset:
Equations of State for Natural and Synthetic Rubber-Like Materials. I Unaccelerated Natural Soft Rubber
Authors: Anthony R. L. , Caston R. H. , Guth Eugene 
Published: February 2011

Abstract
Summarizing, the following important conclusions may be drawn from these experiments on a typical unaccelerated soft gum compound. 1. The existence of the inversion point in the stress-temperature curves is shown to be due solely to ordinary volume thermal expansion, and may be eliminated by correcting for this thermal expansion. 2. The curves given in Figure 8a show that, for compounds of this type, the change of entropy with elongation accounts for more than 90 per cent of the total stress at room temperature, while the internal-energy contribution is less than 10 per cent and, to a first approximation, may be neglected. In other words, the retractive force is due almost entirely to the tendency of the extended rubber molecules to return to a less ordered curled-up state. This is in direct contrast to the elasticity exhibited by ordinary bodies, in which case elasticity is due to intermolecular forces. 3. The contribution of the entropy force to the total force is well represented by the theoretical expression of James and Guth. This agreement constitutes our main reason for interpreting the entropy force as being due to the kinetic motion of the rubber molecules.
Specific Heat of the Synthetic Rubber Hycar-OR from 15° to 340° K
Authors: Bekkedahl Norman , Scott Russell B. 
Published: February 2011

Abstract
Measurements of specific heat were made on a sample of Hycar-OR synthetic rubber from 15° to 340° K by means of an adiabatic vacuum-type calorimeter. The experimental values of the specific heat between 15° and 22° K were well represented by the Debye specific-heat equation, using a βν value of 80 and, accordingly, the values below 15° K were calculated with this equation. At about 250° K the material has a transition of the second order, the specific heat increasing by about 40 per cent to a value of 1.84 Int. joules · gram−1 · degree−1 just above the transition. From 250° to 340° K the specific heat-temperature curve is nearly linear, and the values can be calculated to within 0.2 per cent from the formula Cp=0.00283T+1.126, in Int. joules · gram−1 · degree−1. At 298.16° K (25° C) the specific heat is 1.971 Int. joules · gram−1 · degree−1 (0.4712 calories · gram−1 · degree−1). The increase in entropy resulting from heating from 0° to 298.16° K was calculated to be 1.743 ± 0.002 Int. joules · gram−1 · degree−1 (0.4167 ± 0.0005 calories · gram−1 · degree−1).
Vibration Properties of Rubberlike Materials Dependence on Temperature
Authors: Stambaugh R. B. 
Published: February 2011

Abstract
1. The vibration modulus and resilience are independent of the frequency of vibration if the temperature is constant. 2. The internal friction is approximately inversely proportional to the frequency. 3. The modulus decreases as temperature increases. Curves for synthetic stocks at high temperatures are not very different from those of rubber at low temperatures. 4. Resilience rises linearly with temperature. Rubber shows a transition from one slope to another at about 25° C. 5. The dependence of the internal friction of rubber and similar materials on temperature follows the same exponential law as the viscosity of liquids. At certain critical temperatures sudden changes occur in the cohesive forces, which cause a transition from one curve to another. For the natural rubber sample this occurs at about 17° C. 6. The amplitude of vibration has a large inverse effect on the modulus and friction, which cannot be explained by the temperature rise of the sample due to heat generated in it. The effect may be due to nonlinearity of the stress-strain curves. 7. Modulus and friction are affected by temperature in the same way, indicating the dependence of both on some fundamental characteristic of the molecular structure. Natural rubber requires two straight lines for representation on the modulus-friction plot, the junction occurring at about 25° C.
Sponge Rubber
Authors: Cooper A. 
Published: February 2011

Abstract
It is the object of this paper to deal with some of the less known facts concerning sponge rubber, and not with latex sponge, frothed sponge or sponges made by specialized processes, such as the Goodrich and Lindemann methods already described by Brazier, or sponges produced from rubber solutions and spraying processes, or other specialized methods recently developed. In the manufacture of sponge rubber the greatest problem is the plasticity and uniformity of the raw rubber, and more attention has been given to this than to any other aspect of the manufacture of sponge; yet there is still ample room for development and improvement in this connection. Blending and batching of raw rubber and plasticity control are constantly advocated, and the importance of such standardization cannot be overemphasized. Cold breakdown and mastication, chemical plasticizing and the addition of various softeners, factices and reclaims all have their applications, and can be varied according to requirements. The degree of breakdown of the crude rubber, the use of softeners in the compounded mix and the balance between the type of blowing agent, rates of blowing and curing are the all-important inseparable factors of sponge work.
Production of Industrial Sponge Rubber
Authors: May E. J. 
Published: February 2011

Abstract
The production of sponge rubber for industrial use not only involves the blowing of a mass of plastic rubber compound to a given shape of predetermined density, with concurrent vulcanization, but also the production of a sponge product which will withstand the same severe conditions as will solid rubber produced by modern compounding. Until recent years, the aging and heat-resisting properties of sponge rubber left much to be desired, mainly because of the large surface area susceptible to oxidation, and the large amounts of oils and softeners used to plasticize the rubber. The oils themselves, far from beneficial to aging properties, necessitated in many cases high sulfur ratios to restore the nerve to the vulcanized sponge. It is, however, necessary to plasticize the raw rubber to obtain satisfactory blowing. Within limits, the pore size and density of a sponge from a given stock are governed to a greater extent by the plasticity of the mixed compound than by the amount of blowing agent contained in the stock. To obtain maximum physical properties, the method of plasticizing which has the least deleterious effects on the vulcanized product has to be chosen. This may be one, or a combination of, the following: (1) breakdown of the crude rubber on cool mixing rolls; (2) hot breakdown of the crude rubber at temperatures above 120° C on open rolls or in an enclosed mixer; (3) use of chemical plasticizers; (4) use of plantation softened rubber, such as that produced by the Socfin Co. of Malaya, or by the Schidrowitz-Ungar process, and (5) addition of large quantities of softening oils during mixing.
Resilient Energy
Authors: Bott E. C. B. 
Published: February 2011

Abstract
1. The tensile strength of vulcanized rubber may be expressed in terms of its elongation by means of the calculus of finite differences. 2. This expression for tensile strength, based on the theoretical cross-sectional area, gives an expression for the tensile strength based on the original cross-sectional area when the former quantity is divided by the factor (E + 1), E being the elongation. 3. The expression for tensile strength based on the original cross-sectional area is integrated with respect to the elongation to give the resilient energy. 4. The trapezoidal rule has proved itself to be superior to the calculus of finite differences as a practical method of obtaining the resilient energy. 5. The total resilient energies are plotted on graphs against the percentage by volume of reinforcing agent or filler. Tangents drawn at any desired point corresponding to a certain percentage of filler give values for the partial resilient energies of base mix and of filler by the method of tangent intercepts. 6. The expressions for tensile strength are composed of one, two or three functions ; the number of functions is, in general, inversely proportional to the percentage of the filler in the vulcanizate. 7. The expressions for tensile strength and for resilient energies have no significance regarding the structure of vulcanized rubber; they have been evolved from the point of view of usefulness for evaluating compounds. 8. The values of the partial resilient energies of base mix and of filler obtained by the method of tangent intercepts have no physical meaning; they are a means of calculating the total resilient energy of a sample of vulcanized rubber.
Determination of Total Sulfur in Rubber and Rubberlike Materials
Authors: Cheyney La Verne E. 
Published: February 2011

Abstract
The determination of total or combined sulfur in vulcanized rubber and materials of similar type involves numerous difficulties. This fact is attested by the very large number of methods which have been proposed. All the most important methods involve oxidation of the sulfur, in whatever form it may be present, to sulfate and weighing the latter as barium sulfate. The only essential differences lie in the methods of oxidation employed. The methods which seem to be the most popular at the present time are (1) oxidation of the sample in a Parr bomb with sodium peroxide, potassium chlorate, and sugar; (2) oxidation with perchloric acid and nitric acid, sometimes with the additional use of bromine; (3) oxidation with nitric acid and bromine, followed by sodium carbonate-potassium nitrate fusion; and (4) oxidation with nitric acid-zinc oxide mixture, bromine, and potassium chlorate. Serious explosions have been known to occur with perchloric acid oxidations; hence this method is not so popular at present as the other three. The fusion methods are reliable, but they are time-consuming and therefore not convenient when large numbers of samples must be handled.
A Broad Nomenclature for Carbon Blacks
Authors: Cranor Donald F. 
Published: February 2011

Abstract
The introduction of new carbons for use in rubber and the application of established grades to new uses has led to a confusing terminology. Perhaps it should be said that lack of terminology has led to confusion. Since entry of the United States into the War, reclaimed rubber has been used more generously in tires, including tread stocks, to extend the natural rubber stockpile. This has brought about a considerable use of black of the impingement channel type, which is slightly coarser and somewhat less reenforcing than that previously employed in tire treads. The grade in question has long been available for specialized uses, and has been referred to within the carbon industry as “soft channel black”. However, it is unfortunate that rubber compounders have more recently come quite frequently to refer to this type simply as “soft black”. Intermediate carbons not made by the channel process are now receiving wide attention. These, and a large group of already established grades, are distinctly coarser than the softest channel black, so it is a matter of some importance to exercise care in the nomenclature.
Rubber Photogels. II.
Authors: Stevens Henry P. 
Published: February 2011

Abstract
In a previous communication the writer has shown that the formation of gels from rubber sols on irradiation is often accompanied by an increase in weight so that the solvent and (or) sensitizer apparently reacts photochemically with the solute. The increase in weight of the rubber after removal of the solvent was found to be greater the more rapid the gelation of the sol. It was suggested that this increase in weight might result from products formed by reaction between the solvent and sensitizers independently of the rubber; the product in that case might be rubber physically associated with such photochemical products. This seemed unlikely, as prolonged extraction of the moist or dried photogels with acetone and alcoholic potash removed only a part of the increase. As a further check, a mixture of solvents and sensitizers without rubber was irradiated in sealed tubes and the products were examined. These experiments have been repeated by exposure to sunlight in a window with southern aspect for a whole year. In some cases small quantities of nonvolatile substances were obtained, but these were readily soluble in acetone and, therefore, did not account for the increase in weight, or at least for only a small part of it, and that part was acetone-soluble. It appears, therefore, that any reaction which takes place on insolation between the solvents, with or without additional sensitizers, cannot account for the observed increase in weight of dried photogels. The conclusion is reached that a photosynthesis has taken place, and that the gels consist of a rubber reaction product, at least where an increase in weight takes place.
The Vapor-Pressure Equations of Solutions and the Osmotic Pressure of Rubber
Authors: Miller A. R. 
Published: February 2011

Abstract
1. The laws which are obeyed by ideally dilute and by perfect solutions have been obtained by Guggenheim, and he has extended his analysis to obtain the properties of a class of solutions to which the name regular has been given. It is assumed that the solution consists of molecules of two types, α and β, of approximately the same size, and that each molecule, whether of type α or of type β, is surrounded by the same number z of other molecules, and the potential energy is regarded as the sum of contributions from each pair of molecules in direct contact. That is, the molecules are regarded as occupying sites on a regular lattice, and the potential energy arises from the interactions between molecules which occupy closest neighbor sites. Rushbrooke has examined the properties of such a solution, using the Bethe method to set up the partition function for the assembly. The properties of solutions in which the molecules of one type are of such a size and shape that they have to be regarded as occupying two lattice sites have been investigated by Fowler and Rushbrooke, who determined the limiting form of the vapor-pressure equations for extremely dilute and for extremely concentrated solutions. Chang has determined, for a two-dimensional lattice, the value of the combinatory factor, which can be written as g2,1(Nα,Nβ) for the case in which each molecule of type a occupies two closest neighbor sites and each molecule of type β occupies one site. Chang's determination of g2,1(Nα,Nβ) for a two-dimensional lattice is based on an analysis of the corresponding adsorption problem, in which he superimposes some arbitrary assumptions on the Bethe method. It has, however, been shown that the value which Chang obtained for g2,1(Nα,Nβ) is applicable to two- and to three-dimensional lattices in which no two closest neighbors of a given site are also closest neighbors of one another. Fowler and Guggenheim have shown how, once the combinatory factor has been evaluated, it can be used to determine the configurational entropy of mixing and thence the vapor-pressure equations when the energy of mixing is zero. Using Chang's value for g2,1(Nα,Nβ), they obtained for the vapor-pressure equations, when each solute molecule occupies two closest neighbor sites on the lattice and each solvent molecule occupies only one lattice site, the following equations:
The Change in the Raman Spectra of Chloroprene and Isoprene in the Polymerization Process
Authors: Gantmacher A. , Medvedev S. 
Published: February 2011

Abstract
1. When chloroprene and isoprene polymerize, besides the frequency characterizing the conjugate double bond in the monomer, there appears a higher frequency corresponding to the isolated double bond in the polymer. In the polymerization process, the intensity of the frequency of the conjugate double bond decreases and the intensity of the frequency of the isolated double bond increases. Because of the increase in the number of single bonds in the polymer, the intensity of the frequency of the single bond 1005 in the polymer is considerably greater than in the monomer. 2. Even in the case of the samples with high polymer contents (greater than 50 per cent), the intensity of the frequency of the conjugate double bond is considerably greater than the intensity of the frequency of the isolated double bond. This is attributable to the fact that part of double bonds disappear during polymerization. 3. The Raman spectra of the chloroprene and isoprene polymers differ essentially from those of the monomers. To characterize the frequencies of vibration in the polymer molecule, it is essential to investigate its Raman spectrum in a medium free of the monomer. 4. The formation of highly polymeric molecules on polymerization does not result in an increase in the intensity of the continuous background in spectrograms.
The Solubility of Sulfur in Butadiene-Styrene Copolymer
Authors: Williams Ira 
Published: February 2011

Abstract
The solubility of sulfur in rubber has been studied sufficiently for the various phenomena connected with solubility to be well known. Among the important factors are the available concentration of sulfur at any temperature, the diffusion of sulfur in the rubber, blooming of both vulcanized and unvulcanized rubber, and the effect of supersaturation on the formation of bloom. Similar studies have not been reported on synthetic rubbers which are vulcanized with sulfur. The present paper deals with the solubility of sulfur in a butadiene-styrene copolymer. This work was conducted with a copolymer prepared from 75 parts of butadiene and 25 parts of styrene. The polymer contained about 6 per cent of acetone-extractable material, consisting largely of phenylnaphthylamines and soap-forming acids, particularly stearic acid. It was the general type proposed for large-scale production, and was characterized by lack of tack, nerviness, and short break, especially when hot. The general method employed was one already described, and later employed in a modified form. In general, it consists in the observation, with a low-power microscope, of known amounts of finely divided sulfur dispersed in rubber when very slowly heated and cooled in a hot stage. The solubility temperature is taken as the temperature at which all the sulfur disappears, and the limit of supersaturation is determined by the temperature at which the sulfur reappears when the rubber is lowly cooled.
Effect of Temperature on Resilience of Natural and Synthetic Rubber
Authors: Jones H. C. , Snyder E. G. 
Published: February 2011

Abstract
The necessity of the substitution of synthetic elastomers for natural rubber has been forced on the rubber compounder by the exigencies of war. His background of a hundred years of research and compounding is his principal weapon for making this conversion in the shortest possible time. Too often he finds that this background fails and that practices invaluable in the development of natural rubber stocks are worthless in the case of synthetic rubber, or at least are subject to a different interpretation.
A Method of Testing the Elasticity of Synthetic Rubbers at Low Temperatures
Authors: Kish George D. 
Published: February 2011

Abstract
With the appearance of many new synthetic rubber compounds, the need has arisen for quick and practical testing to determine their comparative applicability to uses formerly filled by natural rubber compounds. One of the most important points is the elastic behavior of synthetic rubbers at low temperatures, and such information is imperative when synthetics are to be introduced into the design of a new product. To obtain accurate data, an instrument termed an Elastensometer was devised.
Aging of Rubber in the Oxygen Bomb at Room Temperature
Authors: Scott J. R. 
Published: February 2011

Abstract
The work described below was carried out as a first step in determining whether an oxygen-bomb test at room temperature could be used as an accelerated aging test for unvulcanized rubber compositions, e.g., as used on surgical and adhesive plasters and for combining shoe fabrics, because a high-temperature test is unsatisfactory in such cases, owing to the melting of the compositions. The only infallible way of assessing the value of an accelerated test for such compositions is by comparison with natural aging, but as this is a very lengthy process and as the deterioration is difficult to measure quantitatively, it was decided to make preliminary tests on the effect of high oxygen concentration at room temperature by using vulcanized rubber. Although the results proved to be negative so far as the original purpose of the work was concerned, it is considered of interest to place them on record in view of the prominence given in some papers on aging to the relationship between oxygen concentration and rate of oxidation and deterioration of rubber. A mix composed of rubber 100, sulfur 3, zinc oxide 5, stearic acid 1, and diphenylguanidine 0.75, was vulcanized for 30 minutes at 153° C. Tensile tests, using standard ring-specimens and the Schopper machine, were made on unaged specimens and on specimens that had been aged (1) in an oxygen bomb at 300 lb. per sq. in. oxygen pressure and at room temperature (about 10° C), (2) in a Geer oven at 70° C. Four rings were used for each test, the tensile strength and breaking elongation figures quoted being the average for the two rings giving the highest tensile strength, and the figures for the elongations at constant loads the average of all four rings.
Characteristics of Wild Rubbers
Authors: Tristram G. R. , Gee G. , Treloar L. R. G. , Jeffrey G. A. 
Published: February 2011

Abstract
The work leads to the conclusion, which can be stated with considerable confidence, that the rubbers examined are without exception polyisoprene rubbers, identical in their chemical constitution, and, when purified, similar in physical characteristics, to ordinary Hevea rubber.
The Kinetics of High Elasticity in Synthetic Polymers
Authors: Tuckett R. F. 
Published: February 2011

Abstract
The simple Mark-Kuhn theory of high elasticity of rubber has been extended, on the basis of the work of Alexandrov and Lazurkin, to cover the elastic properties of other polymers. The chief principle invoked is that high elasticity is developed only when rotation of the main C—C chain in the polymer is comparatively free. The effect of molecular structure, plasticizer and cross-links on elastic properties has been indicated, and also a connection with other observed physical properties, such as volume expansion, dielectric dispersion and specific heat.
The Kinetics of Rubberlike Elasticity
Authors: Eley D. D. 
Published: February 2011

Abstract
1. The treatments of relaxation phenomena in polymer systems, due to Kuhn, and Alexandrov and Lazurkin, are outlined and discussed. 2. Eyring's rate equation is used to analyze the rates of orientation of long-chain molecules in a stressed specimen of lightly vulcanized rubber. The data are compared with similar data on viscous flow in raw rubber, and it is suggested that the segment size for movement is the same in both cases. In viscous flow, the segmental movement occurs without appreciable internal rotation within the segment. In elastic orientation, however, it appears that a high degree of internal rotation within the segment accompanies the formation of the activated state. 3. The activation energy for the orientation of long chains is separated into two terms: (1) the energy required to free a segment from its neighbors, (2) the energy of activation for rotation around C—C bonds. It is suggested that the main effect of vulcanization and plasticizers is on term (3); vulcanization tends to increase this term, plasticizers to decrease it. 4. Data on the dielectric dispersion of polyvinyl chloride suggests the need for internal rotational activation in this case, as in orientation elasticity. This is in agreement with what we should qualitatively expect. Possible complications due to crystallinity in rubber at high extensions or low temperatures are briefly discussed.