bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abrasion and Wear of Rubber. Analysis of Wear Curves
Authors: Buist J. M. 
Published: February 2011

Abstract
One of the difficulties of assessing wear test data of rubber articles, e.g., tires, soles and heels, etc., is the fact that the wear index is not necessarily constant throughout the wearing trial. In a previous publication it was suggested that before exact correlations could be established between laboratory and service tests some mathematical method of obtaining constant indexes for both tests must be found. In the subsequent discussion of this paper at Birmingham, the author revealed that wear curves obtained on the Martindale abrasion tester and also some actual road wear curves could be expressed satisfactorily by an equation of the type y=axn. Since that time further work has been done, and it is now proved that if wear curves obtained on a wide range of laboratory machines, e.g., Martindale, du Pont, and Dunlop (Lambourn), are plotted, these curves are all of the same family y=axn. Although this equation is purely empirical, it is of considerable interest to the rubber industry in that it has such a broad application in the field of laboratory abrasion testing and also in service wear trials.
The T-R (Temperature-Retraction) Test for Characterizing the Low-Temperature Behavior of Elastomeric Compositions
Authors: Svetlik J. F. , Sperberg L. R. 
Published: February 2011

Abstract
The utility of the T-R test for determining the freezing points of elastomeric compounds and their tendency to crystallize has been demonstrated. The freezing point is not appreciably influenced by elongation, but from an operational standpoint it is preferable to employ 50 per cent extension of the sample. To determine the tendency to crystallize on cold storage a 50 per cent test elongation is optimum. To determine if a stock crystallizes on stretching the determination must be made at a series of elongations, or a minimum of two test elongations such as 50 and 200–300 per cent. Materials which crystallize almost immediately at low temperature are readily recognized. All materials which crystallize exhibit sluggish retraction characteristics, whether the crystallization is spontaneous, induced by cold storage, or by extension. The T-R test is simple to perform, highly reproducible, and very versatile. A complete characterization of the low-temperature properties of an elastomeric compound can be made by means of the T-R test in a shorter time than by any other method or combination of methods.
Deterioration of Rubber under the Influence of Light and Dry and Moist Heat
Authors: Soden A. L. , Wake W. C. 
Published: February 2011

Abstract
A comparison has been made of the aging of rubber compounds under tropical conditions. Two localities were chosen, one of which has a dry climate, the other heavy rainfall and high humidity. The results are compared with those obtained by ordinary Geer oven aging and by aging at the same temperature, but with 100 per cent relative humidity. This artificial moist heat aging is found to be much more severe than the tropical moist aging, but it is not different in kind to aging in a Geer oven and a simple conversion factor can be used to transpose results. Samples aged under dry conditions in the tropics are more influenced by bright sunlight, even though shielded from its direct rays, than by the heat aging. Recommendations are made concerning both the use of materials in the tropics and methods of accelerating aging to assess their behavior in the tropics.
Study of the Mechanism of Surface Deterioration of Ebonite and of Means of Preventing Deterioration
Authors: Whorlow R. W. 
Published: February 2011

Abstract
Following up earlier work on the subject, experiments are reported showing that the deterioration of the surface resistivity of ebonite caused by a particular quantity of light increases with decreasing intensity of illumination, and from the results of exposures to different types of radiation it is concluded that the surface temperature of the ebonite during exposure is the most important variable causing this difference. The observed effects are explained by assuming that sulfurous acid is produced as an intermediate product in the deterioration, and that this may either decompose to sulfur dioxide and water, or oxidize to sulfuric acid. If the former reaction is favored by a rise in temperature, the observed influence of intensity and type of illumination, and also the changes in resistivity after ceasing exposure can be explained. Possible methods of preventing or reducing deterioration are discussed, and it is concluded that application of an opaque surface coating, possibly incorporating a suitable basic material to neutralize any acid formed, is the only method likely to be really effective. This method is not possible in many cases. Incorporation of a suitable antioxidant (sym, di-β-naphthyl-para-phenylenediamine was the best of those tested) reduced the rate of deterioration. Where surface coating is impracticable, the use of an antioxidant might be considered, although improvement of resistance to deterioration by a factor of more than three has not so far been achieved by this means.
Oxidation of Olefins Representing Some Structural Units of GR-S
Authors: Warner W. C. , Shelton J. Reid 
Published: February 2011

Abstract
Three olefins were oxidized in the liquid phase with molecular oxygen to determine the kinetics of the oxidation reactions and the relationship to oxidation of rubber. The instantaneous rate of oxidation was found to be related to the analytically determined olefin and peroxide concentrations by the equation : Rate=k (unreacted olefin)(peroxide), where rate equals moles of oxygen per mole of original olefin per hour and the parentheses represent molarities. Presence of a phenyl group was found to affect k, but only in a minor way, indicating that the same fundamental kinetic mechanism applies in both aromatic and aliphatic olefins. The data are consistent with the general kinetic mechanism of Bolland involving oxygen attack at the alpha-methylenic group. However, it appears probable that initial oxygen attack can also occur at the double bond, resulting in the formation of a peroxide biradical, which may then react with other olefin molecules, initiating the usual chain reaction mechanism.
The Nature of Structural Changes of Butadiene Rubbers Caused by High Temperatures (100–200° C)
Authors: Kuzminskii˘ A. S. , Shokhin I. A. , Belitzkaya R. M. 
Published: February 2011

Abstract
In theories developed by Kuzminskii˘ and his collaborators concerning the mechanism of oxidation of rubbers, the question of a direct thermal effect on their structure was not discussed. Nevertheless, with certain rubbers, structural changes which are caused by high temperatures play a very important part in the total complex of structural changes undergone by these rubbers during processing and, after vulcanization, by their products during service. Dogadkin, Zayonchkovskii˘, Zayonchkovskaya, Pisarenko, and Astafyez, Kuzminskii˘, Shanin, Degteva, Lapteva, and other Soviet investigators have shown that, when butadiene rubbers are heated in the temperature range of 100–200° C, structural changes take place which are characterized by increases of tensile strength and modulus, decrease of extensibility, decrease of unsaturation, etc. The question of the causes of such extensive changes in rubber is the subject of this discussion. Rebinder has proven unsubstantiated the reasoning of several investigators regarding these processes, and has shown the necessity of carrying out direct experiments which would provide an explanation of their nature.
Effect of Storage of Milled Rubber on Its Molecular Weight
Authors: Cotton F. H. , Lee K. O. 
Published: February 2011

Abstract
No significant difference was observed between the viscosities of solutions made from milled rubber stored for varying periods. Some crystallization of the milled rubber had occurred, but this did not affect the solution viscosity. The plasticity measurements on the samples cooled with solid carbon dioxide confirm this hardening, but it is apparently an effect unconnected with change in molecular weight.
GR-S Aging in Solution
Authors: Jones Giffin D. , Friedrich Ralph E. 
Published: February 2011

Abstract
Photoscission of GR-S in ethylbenzene solution has been shown to require the interaction of oxygen. In principle then an antioxidant which is not a photosensitizer should function as a light stabilizer. The cause of the failure of the antioxidants studied to function as light stabilizers of GR-S is shown to be related to the occurrence of a very low rate of oxidation of the GR-S despite the presence of the antioxidant. The cause of the viscosity rise in GR-S solutions on autoxidation appears to be the formation of an intermolecular peroxide bond which is subject to induced scission.
Studies of the Vulcanization of Rubber
Authors: Kambara Shu , Ohkita Kumakazu 
Published: February 2011

Abstract
In this study much information about the method of distinguishing the state in which sulfur is combined in simple organic compounds consisting of carbon, hydrogen, and sulfur was obtained, and a new theory of vulcanization was postulated as a result of its application to vulcanized rubber. When activated sulfur reacts with rubber, it first adds to the double bonds, forming thioketones, which in turn, as a characteristic of these radicals, combine with each other, with the formation of a thioether structure. This transformation of thioketone into thioether takes place, not only during vulcanization, but also gradually after vulcanization. Because of the presence of thioketone, treatment of vulcanized rubber with hydrazine, forms a new network, that is, a ketoazine cross-linkage. Combined sulfur of the thioketone type was determined by an oxidizing agent, and as the difference of this value and total combined sulfur a method of determining bridge type of combined sulfur has been proposed. By this method, it was found that, even in ebonite, about one-third of the combined sulfur is the thioketone type, and that the bridge type is only about two-thirds of the total. The thioketone type of combined sulfur in soft vulcanized rubber is transformed gradually into the thioether type of cross-linkage when allowed to stand at room temperature, and this transformation is accelerated when the temperature is raised. In the case of hard rubber, this phenomenon is also observable, but the rate of this transformation is much slower compared to the former. This tendency is the same in the case of ketoazine cross-linking when rubber vulcanizates are treated with hydrazine. From these facts, it seems that the distribution of the thioketone radicals is not uniform, and the magnitude of the probability for collision of these radicals to form cross-linkages has a great influence on the properties of rubber after vulcanization. That is, the property of the vulcanizate is greatly affected by the fact whether the thioketone radicals in the vulcanizates are comparatively uniformly distributed or whether they exist in sectional groups or in colonies. The authors are the first to advance this postulate concerning the chemical structure of vulcanized rubber and its transformation. We believe that when the study is extended, using this postulation, problems such as aging and the differences in the properties of vulcanized rubber accelerated with various accelerators will become clear. Moreover, we believe that it will be of interest to physicists studying rubber elasticity to suggest this idea of colony of cross-linkages. We are now carrying on researches on these problems, and we shall report on them later.
Diffusion of Oxygen and Oxidation of Rubbers in the Presence of Phenyl-β-Naphthylamine
Authors: Kuzminskii˘ A. S. , Shanin L. L. , Lezhnev N. N. 
Published: February 2011

Abstract
We know now that the oxidation of rubbers takes place in the absence as well as the presence of antioxidants. However, the mechanism and the rate of the free and inhibited processes are altogether different. In the presence of a sufficient quantity of a good antioxidant (“true inhibited oxidation”), oxygen takes part almost exclusively in the immediate process of oxidation of the rubber, while the developing active centers are deactivated by reacting with the antioxidant. During free autocatalytic accelerated oxidation, the oxygen takes part in various processes; it initiates a chain process in which it takes part, and also causes many secondary reactions, including most of those which cause rupture of the reactive chains. In this article we shall discuss only true inhibited oxidation, which is especially important from the practical viewpoint.
X-Ray Analysis of the Molecular Structure of Rubbers. X-Ray Diffraction of Amorphous Rubber
Authors: Kasatochkin V. I. , Lukin B. V. 
Published: February 2011

Abstract
The potentialities of x-ray analysis of the molecular structure of rubbers can be widely extended by measuring the intensities of the amorphous halo and continuous background of scattering in the diffraction patterns of unstretched test-specimens. This method can be applied to the study of the effect of repeated stretching of rubbers. Questions pertaining to the fatigue of rubbers have immense importance now in the performance of rubber products. The methods of determining the crystallization of natural rubber and of measuring the intensity of the amorphous halo for synthetic rubber were employed for investigating the changes of the molecular structure of rubber due to repeated stretching. The crystallization of raw smoked-sheet rubber decreased as a result of fatigue; a similar phenomenon was observed for its vulcanizates. The vulcanizates which were stretched less than 300 per cent lost their crystallization property altogether after fatigue, and, at greater elongations, the content of the crystalline phase greatly decreased (see Figure 1).
Evaluation of Tread Wear
Authors: Stechert Dietrich G. , Bolt Thomas D. 
Published: February 2011

Abstract
The observed existence of a linear log-log relationship between nonskid loss and mileage in a great number of widely different types of tests may be exploited in order to realize substantial savings in the road testing of tires for tread wear. In many evaluations it is common practice for the Gates Rubber Co. to test tires to one half initial nonskid depth or to some arbitrary mileage only. The regression line and mileage to baldness are then determined. Of course, the greater the amount of data, and the more accurately controlled the conditions of testing, the more reliable will be the mileage to baldness. If in tread wear evaluations tests were terminated prior to baldness, about $180 could be saved for each passenger tire tested, and $490 for each truck tire, for every 10,000 miles. One investigation, to determine the effect of three different tire designs on tread wear, was made at a total cost of $2200. If all tires had been tested to baldness, the cost would have been approximately $4600. In comparison with former common practice, the application of the proposed method of analysis of tire wear measurements can result in more reliable tread wear evaluations, more economical utilization of the tire test fleet, and a more rapid turnover of ideas.
Migration of Materials during Accelerated Aging by the Oxygen Pressure Method
Authors: Fackler Marion B. , Rugg John S. 
Published: February 2011

Abstract
It has been definitely established that various materials migrate and that the magnitude of the resulting error is significance Migration takes place whenever unlike stocks are aged together in a bomb. The most reliable test conditions prevail when separate bombs are used for individual stocks. It is recommended that specifications for oxygen-bomb aging be changed. The change should specify the use of individual bombs.
Determination of Free Sulfur in Vulcanized Rubber Mixtures
Authors: Frey Horst 
Published: February 2011

Abstract
Numerous papers on the determination of free sulfur in rubber mixtures have been published. Most of these are in the older literature, and they offer various methods for determining free sulfur. In principle the methods can be divided into two general groups. The procedures described in the first and larger group involve preliminary acetone extraction before the actual determination of the free sulfur, whereas the methods comprising the second group, which include only two different procedures, do not involve acetone extraction. Of these two methods, only that of Oldham, Baker, and Craytor has found widespread acceptance.
Determination of Total Sulfur in Vulcanized Rubber Mixtures
Authors: Frey Horst 
Published: February 2011

Abstract
A method is described, which, by means of a resin ion-exchange agent, makes possible the elimination of the disturbing effects of foreign cations, particularly iron and chromium, in the determination of the total sulfur in vulcanized rubber mixtures. By this procedure, rapid volumetric methods for determining sulfate, even in the analysis of mixtures containing iron oxide or chromium oxide pigments, can be utilized. The procedure involves precipitation of the sulfate by benzidine and determination by titration with aqueous sodium hydroxide. The method is more rapid and more reliable than ordinary gravimetric methods involving precipitation of barium sulfate.
Temperature Rise in the Rubber in Rotation Plastometers
Authors: Whorlow R. W. 
Published: February 2011

Abstract
The temperature rise that occurs on shearing rubber at high rates in the shearing-cone plastometer has been measured and shown to be about double that which is to be expected from simple theoretical considerations. This discrepancy is apparently due to heating of the rotor. The temperature rise in normal Mooney plastometer tests may be great enough to influence significantly the results, particularly during scorch tests, but relative results on stocks of not very different plasticities (as in control tests of a given mix) would not be appreciably affected.
Quantitative Characterization of Cure. I. Relationship between Modulus and Strain of Pure-Gum Natural-Rubber Vulcanizates
Authors: Blackwell R. F. 
Published: February 2011

Abstract
The object of this investigation was to determine whether the relationship between strain (elongation) and modulus is sufficiently close for one to be calculated from the other. Stress-strain data have been recorded for loads of 2–10 kg. per sq. cm. for a series of ACS1 and other pure-gum compounds. It is shown that the strain at a fixed stress (5 kg. per sq. cm.) is uniquely related to the load required to produce an elongation of 100 per cent. A tentative explanation of this observation is given in terms of the Mooney equation for the stress-strain curve. It is shown that the second constant of this equation does not vary greatly from rubber to rubber.
Quantitative Characterization of Cure. II. Use of Modulus as a Measure of the State of Cure of Pure-Gum Natural-Rubber Vulcanizates
Authors: Fletcher W. P. , Gee Geoffrey , Morrell S. H. 
Published: February 2011

Abstract
The purpose of this investigation was to develop methods of measuring state of cure which involved only measurements normally available or very readily made. Swelling measurements, although suitable in theory, suffer the practical disadvantage of being time-consuming, but it is shown that they can be replaced very satisfactorily by modulus at 100 per cent elongation. This is a good practical measure of state of cure for most purposes, and simple corrections are developed which extend its range of usefulness. An easily constructed machine is described for the accurate measure of modulus at small elongations.
Viscoelasticity of Rubber
Authors: Blizard Robert B. 
Published: February 2011

Abstract
A theory has been obtained for the viscoelastic behavior of rubber in the frequency range above that at which creep is important and below that at which it behaves like a hard solid. The rubber chains are treated as springs in a viscous medium, and a general expression is obtained for the contribution to modulus of a single section of chain as a function of its length and terminations. A statistical estimate is made of the number of chain segments having given length and terminations. A modulus function is found for the group of chains with each kind of termination, and these are added in the proper amounts to give the form of the modulus vs. frequency curve for any amount of cross-linking. Measurements of shear modulus were made on one apparatus at frequencies between 0.0125 and 750 cps. Agreement is good if a pure viscosity is added to the theory. However, at low frequencies the imaginary part of modulus does not decrease as much as predicted.
Formation of Bound Rubber of GR-S Type Polymers with Carbon Blacks
Authors: Duke June , Taft W. K. , Kolthoff I. M. 
Published: February 2011

Abstract
The bound rubber-black complex formed by milling various GR-S polymers and carbon blacks at several temperature levels was studied. The amount of bound polymer increased with greater loadings of black, but per unit of carbon black, it decreased at the higher black loadings. The temperature of mixing likewise has a large effect—at lower carbon black loadings, higher temperatures increase the amount of binding; the effect ia minimized as the loading is increased until at high loadings (100 to 125 parts of black per 100 parts of rubber) this effect is eliminated. By fractionation of the sol portion, it has been shown that polymer of progressively lower molecular weight is bound as the black loading is increased. Polymer of high molecular weight does not replace bound polymer of lower molecular weight; the polymer of higher molecular weight is preferentially bound during mill mixing. Although more polymer appears to be bound as the conversion is increased from 50 to 72 per cent at a loading of 50 parts of black, other factors besides conversion may be determinative. No differences in relationship were found for polymers made at 122° or 41° F.
Application of the Measurement of the Dielectric Constant and Loss Angle to the Study of the Structure of Vulcanizates Loaded with Carbon Blacks
Authors: Thirion P. , Chasset R. 
Published: February 2011

Abstract
In the case of vulcanizates containing carbon black the variation curves of dielectric loss angle as a function of temperature enable the Debye type absorption occurring in the rubber matrix to be distinguished from a supplementary absorption little influenced by variations in temperature and frequency which is characteristic of blacks possessing a structure. The experimental results obtained indicate no difference in physical or chemical state between the matrix occupying the space between the particles of black in a loaded mix and the vulcanizate of the corresponding pure rubber mix. The supplementary losses on the other hand seem to be closely related to the effects of structure in loaded mixes imagined by Mullins to explain the mechanical behavior of these mixes: they decrease very rapidly by elongation or swelling and give rise to various phenomena of hysteresis. It would seem that dielectric absorption could advantageously be applied as a nondestructive test revealing the colloidal structure of rubber mixes based on carbon black. Moreover the dielectric constant would enable information to be obtained on the form factor and the orientation of the particles or agglomerates of particles of black in mixes on the basis of a theory assimilating these particles (or agglomerates) to condenser armatures.