bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bonding of Rubber to Metals
Authors: Buchan S. 
Published: February 2011

Abstract
Rubber has been used for many years as a medium for minimizing and absorbing mechanical vibrations. Until comparatively recently, however, its employment for this purpose has been limited by the practical difficulties encountered in uniting it successfully with other more rigid materials, such as metals. At this stage, technical development in the rubber industry fell short of engineering design and manufacturing requirements. Earlier methods for uniting rubber to metal consisted either of attaching the rubber by mechanical means or by using a layer of ebonite between the soft rubber and the metal. These methods, however, were open to criticism, either on mechanical or chemical grounds, and the bond strengths were obtained at the expense of some of the flexibility of the units. Later, derivatives were produced by the action of sulfuric acid on rubber which gave excellent bonding properties, although they were thermoplastic and tended to weaken at temperatures over 60° C. Recently, cements based on rubber hydrochlorides have been put on the market which are superior in all respects to previous types. These are the “Ty-plys”.
Deterioration of Vulcanized Rubber by Copper and Manganese Compounds
Authors: Bott E. C. B. , Gill L. D. 
Published: February 2011

Abstract
The deterioration of vulcanized rubber containing increasing percentages of copper and manganese compounds and the extent of the protection given to the stocks by a secondary naphthylamine have been investigated. Jones and Craig showed that the addition of copper stearate made no difference to the type of aging of stocks containing various percentages of antioxidant when measured by decrease in tensile strength, and the results of Taylor and Jones indicate that the decrease is proportional to the time of aging in the Geer oven. Preliminary work.—Experiments were made on the base mix to determine its suitability and its optimum cure. The optimum cures of the base mix plus copper or manganese compounds after storage for six weeks in the dark at normal room temperature and of the base mix plus sym. di-β-naphthyl-p-phenylenediamine also were obtained. The following compounds A, B, C and D were mixed on a laboratory mill having 12 × 6 in. rolls.
Physical Methods of Analysis of Synthetic and Natural Rubber
Authors: Barnes R. Bowling , Williams Van Zandt , Davis A. R. , Giesecke Paul 
Published: February 2011

Abstract
In a compounded rubber stock, the ratio of natural to synthetic rubber can be estimated approximately from a knowledge of the phosphorus content of the rubber hydrocarbon. A considerably more exact analysis can be carried out by infrared spectroscopic methods, which permit a determination of the type as well as the amount of rubber present. Complete details and comparative results of these two methods of analysis are given, as well as a simple procedure for separating the rubber hydrocarbon of a rubber stock from carbon black and other compounding ingredients.
The Elasticity of a Network of Long-Chain Molecules. II
Authors: Treloar L. R. G. 
Published: February 2011

Abstract
Wall's treatment of the elasticity of a molecular network is extended to cover the general homogeneous type of deformation of rubber. An equation is derived for the work of deformation in terms of the three principal strains, from which certain general stress-strain relations are deduced. These relations involve only one physical constant of the material. The use of the formulas is illustrated by their application to a number of simple cases. It is shown that the effective rigidity in respect of a shear in a plane at right angles to a previous elongation is inversely proportional to the elongation.
Macromolecular Compounds. CCXCII Polyisobutylene
Authors: Staudinger H. , Bebger G. , Fischer Kl. 
Published: February 2011

Abstract
An explanation of the chemical constitution of macromolecular substances has to a great extent been made possible by the preparation and study of various homologous series of polymers. In these investigations, the relations between the average degrees of polymerization and the physical properties of the particular substances concerned were studied. As a result of these studies, it was found that the unusual physical properties of macromolecular substances, such as toughness, elasticity, swelling in liquids, and above all, the colloidal nature of their solutions, are dependent on the size and form of their macromolecules, and not on a special micellar structure, as had been so widely assumed previously. It has been found possible to prepare a complete series of homologous polymers, starting with the low members, and passing through the hemicolloids and mesocolloids, to the highest molecular members, the eucolloids, by polymerization of vinyl derivatives under various conditions. It has not been found possible, however, to prepare a complete series of homologous polymers from all vinyl derivatives. At present, for example, there are still no known eucolloid members of polyindenes and of polyanetholes. On the other hand, in the polymerization of styrene, vinyl chloride, acrylic esters and vinyl acetate, it has been found possible to prepare, by the proper choice of conditions during polymerization, members extending from hemicolloids to eucolloids. An analogous complete series of homologous polymers can be prepared from polyisobutylenes. In this case it is possible, by the choice of various catalysts, to obtain polymerized products extending from the lowest to the highest degrees of polymerization. The hemicolloid members of this series are used technically as lubricating oils; the mesocolloid and eucolloid products are of importance in other ways because of their rubberlike properties.
Macromolecular Compounds. CCCII. Polymerization of Acrylonitrile. Polyacrylonitrile
Authors: Kern Werner , Fernow Helmut 
Published: February 2011

Abstract
Products obtained by the polymerization of vinyl compounds and acryl compounds are among the most important of synthetic organic materials. Each of these unsaturated compounds imparts special properties to the simple polymers and mixed polymers prepared from them, and it is because of these special properties that the polymers have found such wide application. Acrylonitrile, for example, is used technically on a large scale, particularly as a component in mixed polymerizations, and it imparts characteristic properties to the mixed polymers, e.g., resistance to organic solvents. In contrast to most other polyvinyl and polyacryl compounds, polyacrylonitrile is insoluble in organic solvents, and because of the unusual behavior of this polymer, it seemed of interest to study the polymerization of acrylonitrile and some of the products of its polymerization. In the polymerization of vinyl compounds, either soluble or insoluble polymers are obtained, depending on the type of monomer and the choice of operating conditions. Styrene, vinyl acetate, methacrylonitrile, and acrylic and methacrylic esters of monohydroxy alcohols yield soluble polymers. On the contrary, when divinylbenzene and likewise acrylonitrile are polymerized, insoluble polymers are obtained. Vinylmethyl ketone, butadiene and other compounds yield either soluble or insoluble products, depending on the experimental conditions.
Statistical Thermodynamics of Rubber. III
Authors: Wall Frederick T. 
Published: February 2011

Abstract
The kinetic theories of rubber elasticity which have been developed within recent years have grown out of one fundamental idea, namely that the elastic forces involved are due to the thermal motions of the molecules rather than to deformations of valence bonds and angles. In deriving theoretical equations of state for rubber, the usual procedure has been to connect entropy concepts with the probability functions for molecular shapes, assuming that molecules can have different shapes as a result of rotation about some of the valence bonds. Although the various authors started with substantially the same idea, their theories differed as to the way in which entropy changes were calculated. Recently, however, Treloar has shown that by eliminating certain approximations from Kuhn's treatment, then Kuhn's theory gives precisely the same result as does the theory of the present author. A basic postulate of the author's theory and of Kuhn's theory as amended by Treloar is that, when a piece of rubber is deformed, the components of the lengths of the molecules change in the same ratio as the corresponding dimensions of the rubber. To illustrate this specifically, let us consider a one-dimensional problem. If x is the component of the length of a molecule in the direction under consideration, then for a piece of unstrained rubber the probability of finding a molecule with a value of x in the range x to x+dx will be given by:
Stability of Butadiene
Authors: Robey Richard F. , Wiese Herbert K. , Morrell Charles E. 
Published: February 2011

Abstract
1. The most prominent polymerization of pure butadiene in the absence of peroxides is dimerization. This reaction is thermally activated, and does not appear to be catalyzed by peroxides or by steel surfaces. 2. Butadiene is also capable of independent polymerization to high-molecular-weight polymer, but in the absence of peroxides this reaction is insignificant compared to dimerization. The effect of temperature on the rates of each of these reactions has been determined. 3. In the presence of appreciable amounts of peroxides, polymerization to high-molecular-weight polymer becomes prominent, and is superimposed additively on the thermal dimerization reaction. 4. The addition of suitable antioxidant inhibits the formation of high-molecular-weight polymer, but has no appreciable effect on the rate of dimer formation. 5. The rate of high-molecular-weight polymerization is directly proportional to the square root of the concentration of peroxides (active oxygen). 6. Butadiene is readily peroxidized by air, but this peroxidation may be inhibited for a time by the presence of antioxidants. 7. The peroxides are not readily volatile, and tend to accumulate in the residue if the diene is evaporated or distilled away. Concentration beyond a certain point yields an unstable residue which may decompose with violence when heated. Precautions for distillation of such peroxidized material are given.
Froth Flotation of Rubber and Resin Components of Milkweed and Other Plants That Contain Resins, Rubber, Balata, or Related Gummy Substances
Authors: Turrall Wm T. , Klassen J. , Smedley H. 
Published: February 2011

Abstract
Some of the more important features of froth flotation in the separation of rubber-resin from milkweed and other plants are summarized as follows. 1. It removes the bulk of the waste material at an early stage of the operation. 2. In the flotation of the rubber-resin component from milkweed, no additional flotation reagents are needed to cause a separation, but they have been found necessary in the flotation treatment of some other plants. 3. The grade and the recovery of the rubber-resin fractions appear to depend on the size of the agglomerates. 4. Agglomeration of the rubber-resin fraction takes place during ball-milling only when certain conditions are favorable, e.g., density and alkalinity. If conditions are not favorable, the rubber-resin remains fine and well dispersed. Flotation on such a product results in the separation of a rubber-resin fraction. 5. It is not necessary to take the specific gravity of the rubber-resin components into consideration. 6. The flotation method is applicable to the concentration of the rubber-resin components from such plants as milkweed, dogbane, goat's-beard, sow thistle, wild lettuce, and possibly many other plants, with or without the use of chemicals. 7. It presents the possibility of a continuous process of rubber-resin extraction from plants.
Drift and Relaxation of Rubber
Authors: Mooney M. , Wolstenholme W. E. , Villars D. S. 
Published: February 2011

Abstract
Numerous studies have been published on the relaxation and drift, or creep, of soft vulcanized rubber. In the present work, tests of this kind have been extended considerably beyond previously published work, both as to duration of the test and range of the initial stress or elongation. Some compression drift tests have now been in progress for eight years. A new method of measuring stress relaxation at fixed elongation has been developed, particularly with the purpose of conserving space. This method has made it possible and practical to carry out a large number of tests, many of them lasting for many months. An additional advantage of the test is that the samples can be kept in a controlled atmosphere as well as at a controlled temperature. Some of the more extensive relaxation data have been used to test the Tobolsky-Eyring theory of relaxation. Good agreement is obtained by assuming two relaxation mechanisms. An alternative or modified theory of relaxation is presented.
Rubber, Polyisoprenes, and Allied Compounds. VI. The Mechanism of Halogen-Substitution Reactions, and the Additive Halogenation of Rubber and of Dihydromyrcene
Authors: Bloomfield George F. 
Published: February 2011

Abstract
The chlorination of cyclohexene by chlorine or by sulfuryl chloride (in the absence of a peroxide catalyst) yields substituted as well as additive chlorination products, and the former retain in full the original olefinic unsaturation, as indicated by iodine-value determination ; but whereas sulfuryl chloride forms only the additive dichloride and a monochloroölefin which is substituted exclusively in the 3-position, chlorine yields a mixture of saturated trichloro derivative (chloro-substituted addition product) and isomeric monochloroolefins (3- and 4-substituted), with some additive dichloride. No evidence of substitution at the ethylenic methine carbon atom has been obtained in the chlorination of cyclohexene, dihydromyrcene, and rubber by chlorine. The diminished unsaturation of the chloro-substitution products of the last two hydrocarbons is attributed to cyclization—a process which is complete in the case of rubber, but affects only a minor proportion of the molecules of dihydromyrcene. The same cyclizing tendency appears in the substitutive bromination of rubber by N-bromosuccinimide, but not to any appreciable extent in the similar bromination of dihydromyrcene. Additive chlorination products are formed when rubber is brought into reaction with chlorine liberated by the thermal dissociation of phenyliododichloride, or of sulfuryl chloride in the presence of a peroxide. The mode of reaction of bromine with rubber, about which many contradictory statements have been made, is found to be entirely additive if the solvent contains a trace of alcohol and the temperature is 0°. A method based on bromine addition may be used for estimating rubber hydrocarbon. Additive bromo and chloroderivatives of rubber are comparatively stable, and give no indication of the spontaneous elimination of halogen acid, either through cyclization reactions or the reformation of double bonds at temperatures up to 80°. The provision of chlorine in free-radical form appears to be an essential condition for obtaining the wholly additive chlorination of rubber and allied olefins. The reaction of molecular chlorine or bromine, on the other hand, follows a course which can be adequately explained by the initial formation of an activated dihalide, the fate of which is determined by the nature of the olefinic system and the experimental conditions.
Chemistry of Sulfur-Olefin Reactions. Application to Vulcanization
Authors: Armstrong Robert T. , Little Julian R. , Doak Kenneth W. 
Published: February 2011

Abstract
During recent years there has been general acceptance of the theory that the marked alteration in physical properties of rubber, termed “vulcanization”, is a consequence of progressive cross-linking through primary valence bonds. Attempts have been made to place this theory on a quantitative basis in the kinetic theory of elasticity. Accompanying phenomena such as isomerization, cyclization, and degradation reactions (reversion) may occur, and account for the differences observed under various conditions of vulcanization in the early stages or soft rubber range. These secondary reactions probably become very important in the ebonite stage. The vulcanization of saturated hydrocarbon polymers, such as polyisobutylene, has been notably unsuccessful in contrast with polyenes, such as natural rubber, drying oils (to produce factice), and butadiene polymers and copolymers. The vulcanization of polychloroprene (or its conversion from δ-polymer to μ-polymer in Carothers' terminology) can proceed without the addition of other reactants and is, therefore, distinct in type from the others mentioned. The difficulties inherent in a direct study of the chemistry of sulfur vulcanization, when rubber itself is used, follow from the fact that, in the commercial range of soft rubber vulcanizates, only from one to six sulfur atoms are combined for each hundred double bonds; also, the product becomes insoluble even before the lower amount has been combined. In this paper it is proposed, as a working hypothesis, that the chemical reactions which proceed during the vulcanization of natural rubber or diene polymers can be duplicated by the reaction of simple olefins of analogous structure (2-methyl-2-butene or 2-butene). with the vulcanizing agents, and that the pure reaction products have their counterpart in the vulcanizate.
Vulcanization of Buna-S (GR-S) with Organic Sulfur Compounds
Authors: Beaver D. J. , Throdahl M. C. 
Published: February 2011

Abstract
1. Buna-S has been vulcanized by a number of organic sulfur compounds, most interesting of which are alkylxanthogen disulfides. 2. The optimum results were obtained with a stock containing 4.00 per of ethylxanthogen disulfide, with either 2.00 per cent of N-cyclohexylbenzothiazyl-2-sulfenamide or 0.50 per cent of tetramethylthiuram disulfide. 3. The effect of small additions of t-butyl-, xylyl-, and p-methylphenylthiols was a pronounced improvement in the flex-cracking resistance of a vulcanizate containing ethylxanthogen disulfide. These observations suggest the industrial application of ethylxanthogen disulfide to alleviate some of the serious deficiencies so characteristic of Buna-S vulcanizates.
Changes in Physical Properties of Hard Rubber Shortly after Vulcanization
Authors: Daynes H. A. 
Published: February 2011

Abstract
Preparatory to a full investigation of the properties of various specimens of hard rubber, it was considered necessary to decide on a minimum time interval between vulcanization and testing. This was desirable to allow specimens to attain a stable condition, and thus to avoid anomalies which might result from testing during a transition period, soon after vulcanization, when the physical properties are changing relatively rapidly. It was necessary to approach the problem from the standpoint of the following properties which it was desired to investigate.
Strains in an Inflated Rubber Sheet, and the Mechanism of Bursting
Authors: Treloar L. R. G. 
Published: February 2011

Abstract
The two principal strains in a circular sheet of rubber clamped round its circumference and inflated are measured at all points on the surface of the spheroidal balloon thus formed. The principal strains may show relatively-large variations over an area in which the form is nearly spherical and the thickness is approximately constant. The reasons for this, and for certain other effects brought out in the experiments, are discussed. In experiments on the bursting of sheets of various rubbers (natural and synthetic), there appeared to be a general relation between the hardness at the instant of breaking and the number and regularity of the radial tears. From the strain measurements it is concluded that these radial tears are not caused by the relatively slight radial orientation of the molecules in the sheet. A detailed mechanism of bursting is suggested, in which the radial tears are compared with the radial cracks associated with glass fractures.
The Variation with Temperature of the Dynamic Properties of Rubber and Synthetic Rubberlike Materials. II. Compounded Rubbers
Authors: Blow C. M. , Fletcher W. P. , Schofield J. R. 
Published: February 2011

Abstract
The whole of the dynamic modulus results may be summarized as follows. (1) A general sensitivity to temperature over the range studied is shown by all rubbers, natural and synthetic. (2) Natural rubber is least sensitive, followed by Neoprene-GN and GR-S. Next in order come Neoprene-YD and butadiene-acrylonitrile copolymers with low acrylonitrile contents. In general, the higher the acrylonitrile content, the more sensitive to temperature is the polymer. Neoprene-Z is only slightly less sensitive than Hycar OR-15 (45–55). (3) Broadly speaking, the effect of compounding with P-33 black and gas black is to increase the sensitivity to temperature. Notable exceptions are Neoprene-GN and GR-S containing extender, which appear almost unchanged, and Neoprene-YD, which shows a decreased sensitivity with loading. (4) It is evident from the results that any specification for dynamic modulus should be accompanied by a specified temperature of test; in design, account must be taken of the variations which it has been shown can be quite considerable for synthetic rubbers now coming into commercial use, even under normal seasonal variation of temperature. (5) Static methods of determining freeze points, e.g., torsion and bending tests, in general place materials in a similar order with respect to their low-temperature behavior as the present dynamic experiments, although no appreciable temperature effects are noted in the temperature range of the experiments discussed here. The results of resilience measurement are not easy to summarize. Suffice it to say that, over the limited range of temperatures investigated, very great differences in resilience are observed between different polymers. The superiority of natural rubber is again evident, although it is somewhat less marked in loaded stocks. In the case of Thiokol-RD and Hycar OR-15, minima in the resilience curves are indicated at 23° C and about 10° C, respectively. This has been reported by previous workers. In all polymers the resilience-temperature curve is in two parts, with a more or less sharply defined transition point, the temperature of which seems to depend largely on the chemical structure of the polymer. Again this is confirmed to some extent by reference to the literature.