bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Silent Electric Discharges on Rubber Solutions
Authors: Hock Lothar , Leber Heinrich 
Published: February 2011

Abstract
The object of the investigation was to synthesize higher molecular compounds from natural rubber and from synthetic rubber by means of a process involving exposure to silent electric discharges. With both natural rubber and synthetic rubber, it was found possible to bring about polymerization by this method and to obtain polymers of various molecular sizes, which could be separated into two principal types: (1) polymers which remained soluble in benzene, and (2) polymers with a highly developed network structure, which were insoluble in benzene and therefore could be separated from the soluble polymers. After purification and drying, the insoluble polymers were obtained as inelastic, nonplastic products, in the form of soft, crumbly flakes. On the contrary, the soluble polymers retained the plasticity and elasticity of the original rubber, and behaved like raw rubber in the technical sense as well. This latter fact was proved by preparing a few mixtures and vulcanizates from these polymers, and it is noteworthy that a vulcanizate prepared from polymerized Buna-85 more nearly resembled a corresponding vulcanizate from untreated natural rubber than it did a vulcanizate prepared from the original, untreated Buna-85. Of course more extensive development work would be necessary to obtain polymers with particularly desirable properties from a technical point of view, and to find out how to compound these new polymers, e. g., what types and percentages of fillers, accelerators, and percentages of sulfur to use. Only in this way can the technical importance of these products be judged, and can any uses to which they may be applied to advantage be determined. But whatever may be their importance, the increased molecular sizes of these polymers of natural rubber and of Buna-85 are accompanied by marked increases in softening temperature without sacrifice of their technically important advantages of plasticity, tackiness and solubility. To this extent a not unimportant goal from the technical point of view may be regarded as having already been attained.
Destructive Hydrogenation of High-Molecular-Weight Polymers. Isobutene Polymer, Butadiene Polymer, and Natural Rubber
Authors: Ipatieff Vladimir N. , Schaad Raymond E. 
Published: February 2011

Abstract
Destructive hydrogenation under pressure in the presence of nickel oxide and molybdenum oxide has been used to show the presence of naphthenic hydrocarbons in high-boiling olefin polymer. It was of interest to apply this tool to other hydrocarbons having large molecules, especially rubber and synthetic rubber like polymers. The destructive hydrogenation of isobutene polymer yielded only paraffinic hydrocarbons, including isobutane in the gases. Butadiene polymer, on the other hand, gave only naphthenic products, chiefly ethylcyclohexane and a dicyclic hydrocarbon. Similarly, natural rubber yielded only naphthenes, with p-methylisopropylcyclohexane as the major component of the lower boiling portion of the product. Isoprene, under the conditions used for the destructive hydrogenation of the rubber, yielded isopentane and an unsaturated naphthene, i. e., a hydropolymer of isoprene, which was converted into p-methylisopropylcyclohexane by further hydrogenation. Discussion of the relation of these results to the structures of the polymeric substances hydrogenated is reserved for a future publication of further work now in progress undertaken to aid in the proper interpretation of the above indicated experiments.
A Study of Polymers. I. Highly Elastic Deformation of Polymers
Authors: Aleksandrov A. P. , Lazurkin Yu S. 
Published: February 2011

Abstract
1. The proposed explanation of relaxation makes it possible to understand the general law of the dependence of deformation of highly elastic substances on temperature and frequency (time of action). 2. The results of measurements of various substances conform in a qualitative way to the scheme proposed. 3. With respect to mechanical losses, it is shown that application of the simple concept of relaxation makes it possible in many cases to explain the physical nature of the processes involved. 4. It is found that the relations characteristic of various relaxation processes, such as electrical and mechanical processes, are marked by a unity in their physical nature.
A Study of Polymers. II. Dynamic Method of Studying Elastic Materials
Authors: Lazurkin Yu S. 
Published: February 2011

Abstract
Most articles made from elastic substances are intended for service under dynamic conditions. Static methods of investigation are clearly insufficient for determining the behavior of elastic substances under dynamic conditions and therefore there has for a long time been a need for dynamic tests. In recent years several dynamic tests have been developed, and a number of investigations of elastic properties under dynamic conditions have been published. The works of Frumkin, Roelig, Kosten, Naunton and Waring and other investigators have established a series of relations in the behavior of elastic substances under dynamic conditions. However, the limited intervals of frequency and temperature in these experiments gave relations of peculiar character and even led to contradictions. Thus Naunton and Waring showed that, under dynamic conditions (at high frequencies), automobile tire casings act as solid hoops and, according to Roelig and Kosten, the relation between modulus and frequency, though still existing, is of relatively little importance. The development of a concept of the mechanism of highly elastic deformation, and in particular the disclosure of relaxation made it possible for Kornfel'd and Poznyak and Mikhai˘lov and Kirilina to demonstrate experimentally the existence of a more general law relating the phenomena. However, in their experiments, the frequency in both cases changed within narrow limits, and consequently these investigations too do not give a general picture of the behavior of elastic materials in relation to the frequency of deformation and temperature. The idea of highly elastic deformation, as well as that of relaxation, comes down to the fact that the magnitudes of the deformations observed depend on the relation between the time of action of the force and the time required for regrouping of the particles in the substance during the deformation.
Rheologic and Elastometric Measurements of Rubber Products
Authors: Höppler F. 
Published: February 2011

Abstract
A number of raw materials, intermediate products and finished products of the rubber industry were examined, and their rheologic and elastic properties measured by a Höppler consistometer. The initial measurements were carried out with concentrated solutions of rubber and artificial rubber, and flow curves were constructed to show their behavior at various temperatures. The results show that the thixotropic properties of these materials are independent of the temperature. Also flow curves of solid raw rubber products of various degrees of mastication and at various temperatures were constructed and the corresponding quasiviscosity and flow point values were determined. It was proved that the ηQ/t function has a logarithmically linear course and, based on this fact, a new material constant is derived. The elastic and plastic deformations of vulcanizates were studied experimentally on the basis of their resistance to deformation, and it is proposed that the hardness of hard-rubber products be measured and characterized by their cone flow points. All measurements are based on the c.g.s. system.
The Standardization of Rubber Flexing Tests
Authors: Stevens W. L. 
Published: February 2011

Abstract
The present paper offers a method for standardizing rubber breakdown tests which is an adaptation of discriminant function analysis recently developed by R. A. Fisher, and hitherto applied only to the treatment of biological data. The data which form the subject of the present study are rather inadequate, but it is worth while to use them to make the method available for more extensive investigations at a later date. It has, at least, revealed a gross lack of control in experimental technique, and shows that great improvements must be made on the practical side to give the new statistical method a chance to show its real sensitivity.
Control of Gelling in Vulcanizing Cements. Nitroparaffins and Chloronitroparaffins as Inhibitors
Authors: Campbell A. W. 
Published: February 2011

Abstract
The broad application of ultraaccelerators to vulcanizing rubber cements has been handicapped by the formation of irreversible gels, presumably due to partial or complete vulcanization while in solution. The gelling tendency can be overcome by the use of so-called two-part cements, as illustrated in recipe I. Rubber, zinc oxide, and sulfur are mixed on the usual type of mill and then dissolved in a suitable solvent to form one part; rubber and accelerator or accelerators, with or without zinc oxide, and similarly mill-mixed, are dissolved in the same solvent to form the second part. Mixing these two parts in the proper proportions produces a cement containing all the necessary ingredients in the proper proportions for vulcanization. With ultraaccelerators, the mixed cement gels or vulcanizes within a period of hours or days, depending on the accelerator and the accelerator-sulfur ratio. The gel constitutes an economic loss. While two-part cements overcome this gelling, they are not economical of labor and space. It has been found that nitroparaffins and their derivatives will inhibit gelling of vulcanizing cements for long periods. Thus, with many accelerator-sulfur combinations it is possible to make direct mill mixes, followed immediately by churning in the solvent containing the antigel agent. This eliminates half of the mixing and churning usually necessary with ultraaccelerated cements, and permits any unused cement to be stored for use later.
The Molecular Weight and Constitution of Natural Rubber
Authors: Meyer Kurt H. , Wertheim M. 
Published: February 2011

Abstract
As is well known, crepe rubber is prepared from freshly gathered latex by the addition of dilute formic acid, and it contains natural rubber hydrocarbon in unaltered or but slightly altered form. Some years ago Meyer and Mark measured the osmotic pressure of crepe rubber in benzene. At that time the authors based their calculations on an equation derived from the hypothesis that the system was solvated. However, this deduction can no longer be considered valid, for rubber is not solvated in benzene or in toluene, as has been proved recently by Meyer, Wolff and Boissonnas by the fact that solution is accompanied by a slight absorption of heat. In view of this, these earlier results should be evaluated graphically so that the reduced osmotic pressures, p/c, are extrapolated to zero concentration (see Figure 1 and Table I). When evaluated in this way, the limiting value of p/c of 0.5 × 10−3 atmospheres, corresponding to a molecular weight of approximately 500,000, is obtained.
The Optical Properties of Rubber
Authors: Wood Lawrence A. 
Published: February 2011

Abstract
The general survey which has been presented here shows that, while a number of the optical properties of rubber have been investigated, the measurements of most of them have been more or less preliminary or exploratory in nature and often directed towards some immediately practical application. There appears to be ample opportunity for extended, systematic research on the optical properties for their own sake. The results to be expected from such study may lead in two directions, each of them illustrated in a very preliminary fashion, by examples given in the present paper. The one direction is that of more fundamental knowledge of the constitution of rubber, especially when optical methods are used in conjunction with other types of measurement. An illustration already mentioned is the use of molecular refractivity to confirm the existence of a C5H8 unit containing one double bond as the unit group in rubber. Such work might well be extended as assistance in elucidating the constitution of vulcanized rubber. Another illustration is the use of infrared spectra or Raman spectra to determine the types of chemical bonds present in rubber. The other direction in which a study of the optical properties of rubber may lead is toward the direct solution of practical problems without regard for the theoretical significance of the measurements. Problems of control or analysis might be approached in this manner, since optical methods usually require only small amounts of material, and are often easily adaptable to rapid and precise measurements. Such applications have already been illustrated in preliminary form by the use of refractive index to determine amounts of combined or dissolved sulfur. The solution of practical problems by optical methods is also illustrated by the use of the photoelastic method for the analysis of stresses in rubber. Optical measurements in the past have been restricted in most cases to samples having fairly high light transmission. On this account the work has included only unvulcanized rubber and vulcanized compounds of the “pure gum” type. By the use of very thin sections or by employing methods which are based on the reflection of light rather than its transmission, it should be possible to extend the measurements to many practical rubber compounds which appear to be opaque, but which in reality are dispersions of filler particles in a matrix of transparent rubber.
Effect of Reinforcing Pigments on Rubber Hydrocarbon
Authors: Thornhill F. S. , Smith W. R. 
Published: February 2011

Abstract
Several investigators have established that sulfur vulcanization of rubber involves chemical combination of sulfur and rubber hydrocarbon. A definite decrease in unsaturation of the rubber hydrocarbon as vulcanization progresses has been generally noted. While it has often been concluded that a double bond is saturated for each atomic equivalent of combined sulfur, recent work by Brown and Hauserdemonstrates that this conclusion cannot be applied in all cases. In certain compounds they found the loss in unsaturation with extent of vulcanization to be considerably less than anticipated on the basis above. Their results indicate that stocks reaching optimum cure with the least loss of unsaturation possess the greatest tensile strength. Although a considerable amount of work has been done on this problem, we have not found a published account of similar investigations performed on stocks containing significant loadings of reinforcing fillers. Since, as pointed out below, the nature of the bonding between such fillers and the rubber molecules has not been clearly defined, one is not justified in applying previous results obtained on stocks containing no reinforcing fillers to those bearing appreciable loadings of such substances. Accordingly one portion of the present investigation was concerned with determining the effect of various fillers on the course of sulfur vulcanization, as judged from combined sulfur and unsaturation values. As pointed out by Gehman and Field it is undoubtedly true that the black particle in a carbon-black-reinforced rubber stock is firmly attached to the rubber molecule. The nature of the bonding between the black and rubber has not been clearly defined. Some investigators maintain that the association is physical and involves definite forces of adhesion or adsorption; others have suggested the formation of primary valence linkages with rubber hydrocarbon. The opinion of the present authors is that if such linkages are formed, the ethylenic bonds of the rubber molecule would probably be involved. If this latter view is correct, then a specific loss in unsaturation of rubber hydrocarbon, due to the reinforcing filler, should occur. Thus the second objective of the present study was to determine whether it was possible by chemical means to detect such a linkage. If measurable, this effect, together with the surface area determinations reported previously, would be particularly valuable in estimating the reinforcing value of various fillers.
Discoloration of Dried Latex Films
Authors: Blow C. M. 
Published: February 2011

Abstract
In the course of work on the application of latex to textiles, a staining effect was encountered which is the subject of this short note. Briefly stated, an uncompounded concentrated latex was applied to a cotton fabric; some months after manufacture, pink-brown stains developed. The appearance of the stain suggested iron, and both the circumstances and further facts indicated that light was a likely contributory factor. It was established that oxalic acid would not remove the stain, although this fact did not entirely rule out iron, since the rubber possibly prevented access of the oxalic acid. Furthermore, the stain was not removed by acetone, nor was it affected by a soap and soda scour, whereas if the fabric was treated with cobalt linoleate solution so as to oxidize the rubber, the stain was removed with the rubber in the course of subsequent scour. This suggested that the stain was associated with the rubber. An investigation was therefore commenced on the effect of light on the color of dried films of latex in the absence, and in the presence, of iron. The results obtained appear of some interest, and have revealed a phenomenon not previously recorded as far as the author is aware.
Note on the Product of a Reaction between Aqua Regia and Latex
Authors: Wentworth V. H. 
Published: February 2011

Abstract
Arising from experiments to repeat on fresh latex the halogenation experiments made by Baker on ammoniated latex, the sodium chlorate and hydrochloric acid reagents were replaced by aqua regia. After numerous unsuccessful trials with different stabilizers and combinations of mixed acids, a method was evolved which produces a product in the form of a fine free-flowing powder. Sibley stated in a recent lecture that a wide variety of products could be obtained from rubber by reaction with increasing proportions of aqua regia, and this note gives the details of a method of producing an interesting product by the action of aqua regia on rubber in the form of fresh latex.
Equipment for Accelerated Light-Aging of Rubber, and Methods of Evaluation of Ultraviolet Light and Sunlight
Authors: Werkenthin T. A. , Richardson David , Thornley R. F. , Morris R. E. 
Published: February 2011

Abstract
In connection with the development of a suitable light-aging test for evaluating the light-aging properties of rubber, plastics, dyed fabrics, and paints, a considerable amount of research work and literature search was undertaken. The purpose of this article is to make readily available these data to facilitate additional work in the evaluation of the weathering and light-aging of the above-mentioned materials. It is intended to present these data in a somewhat informal style, and to set forth not only the successful experiment, but also those tests which have been disproved as being either impracticable or not applicable to the particular material under investigation. Most of the work has been done in connection with rubber compounds and synthetic rubber-like materials, with the primary purpose of differentiating between satisfactory and unsatisfactory materials from the standpoint of light-aging and weathering resistance. However, there is a secondary purpose which, at present writing, is far more important and outweighs the mere procurement of material, that is, its use in improving rubberlike compounds themselves.
Simple Vulcanizates of Buna-S and Sulfur. Physical and Chemical Properties
Authors: Cheyney La Verne E. , Robinson Arthur L. 
Published: February 2011

Abstract
The earliest vulcanizates of rubber consisted of only two ingredients, rubber and sulfur. Actually, at least one other ingredient, fat acid, was probably present in the so-called acetone extract of the rubber. However, it was not long before the use of other compounding ingredients, especially inorganic accelerators, was developed. After the introduction of organic accelerators, most rubber goods were compounded with them, together with various activators. Simple products containing only rubber and sulfur were practically forgotten. Those in the ebonite range, however, were found to possess interesting properties and were studied in more detail. The only studies of the simple rubber-sulfur system over the entire range from soft to hard rubber have been those concerned chiefly with the mechanism of vulcanization. Houwink presents graphically the variation of stress-strain properties with sulfur content. Blake and Jessup and Cummings present data for such a series, although their samples were vulcanized to the absence of significant sulfur in the free state.
Studies in Compounding Guayule Rubber I
Authors: Hauser E. A. , Le Beau D. S. 
Published: February 2011

Abstract
It has been shown that different solvents used in the extraction of the resin from crude guayule exhibit different time-temperature relations. Of all the solvents tested, 2-furaldehyde was found to be the most efficient solvent for its speed and for the amount of resin extracted. It does not affect adversely the properties of the hydrocarbon.
Macromolecular Compounds. CCCXII. Halogen Derivatives of Rubber Hydrocarbons
Authors: Staudinger Hermann , Staudinger Hansjürgen 
Published: February 2011

Abstract
It has been assumed by Kuhn and by numerous other investigators that the threadlike molecules of rubber are kinked or tangled, both in the solid state or in solution, like the molecules of other high polymers, because of free rotation of their carbon bonds. This characteristic configuration is represented schematically in Figures 1a and 1b. According to this view, the elasticity exhibited by rubber can be explained by assuming that the fibre molecules are straightened out when the rubber is stretched, and return to their original state when the rubber retracts on release of the stress. When they are straightened out in this way, the fibre molecules may arrange themselves in the form of a lattice. On this basis it is easy to account for the well-known fact that rubber crystallizes when stretched. Kuhn has pointed out also that the viscosity law for fibre molecules is in accordance with this kinking or entanglement of such fibre molecules.
The Compounding of Guayule Rubbers. Effect of Various Factors on Physical Properties
Authors: Morris Ross E. , James Robert R. , Caldwell Ernest B. , Werkenthin Theodore A. 
Published: February 2011

Abstract
The authors conclude, from the work reported herein, that commercially available deresinated guayule rubber may best be compounded in the same manner as Hevea rubber, with an expectation of obtaining approximately 75 per cent of the tensile strength of a similar Hevea stock. It is concluded further that deresinated guayule rubber may generally be processed and cured in the same manner as Hevea rubber without sacrificing quality to a greater extent than is done with Hevea rubber.