bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat Treatment and Polymorphism of Gutta-Percha and Balata
Authors: Dean J. N. 
Published: February 2011

Abstract
The hydrocarbon from balata or gutta-percha is polymorphic, and the modification in which it is usually known is the metastable variety, but it can be converted to the stable modification by one of a variety of comparatively simple heat-treatments. The α modification, to which it is converted by the heat-treatment, has somewhat different properties and these are compared. Some beneficial effects are reported which enable gutta-percha products to become the basis of a very superior variety of submarine cable insulation, which has been called K.-gutta. In writing this article the author is indebted to W. S. Smith and H. J. Garnett for criticism and advice and to F. Mattingley and H. F. Wilson and others of the laboratory staff for assistance and coöperation in carrying out this work. Thanks are also due to the Telegraph Construction and Maintenance Co., Ltd., for permission to publish these results.
Modifications of the Gutta-Percha Hydrocarbon. II
Authors: De Jong A. W. K. 
Published: February 2011

Abstract
It was proved by dilatometer experiments that the spongy product contracts between 61° and 64.5°, and that this contraction is not caused by an impurity or by oxidation. An experiment using a pycnometer showed that contraction was accompanied by fusion, and that during fusion with tension at 64.5° to 67° no contraction took place. The products obtained by grinding the spongy product in a mortar and by crystallizing it from a benzene solution in an ice-box showed no contraction; on the contrary after fusion they showed a slight expansion at ordinary temperature. A method is given for obtaining a pure hydrocarbon from sheet balata.
The Refractometry of Rubber and Gutta-Percha Hydrocarbons. I. The Influence of Depolymerization and Oxidation on the Refractive Exponents of These Hydrocarbons
Authors: Kirchhof F. 
Published: February 2011

Abstract
1. The acetone-extractable substances from different natural rubbers have an appreciable influence on the index of refraction of their hydrocarbons. This influence is different in the case of Hevea rubbers from that in the case of African rubbers, for example. 2. The indices of refraction of different kinds of raw rubber after extraction likewise differ appreciably. These differences may be attributed in part to the different quantities of benzene-insoluble non-rubber substances, in part to differences in the degree of polymerization of the different hydrocarbons. 3. A study of the influence of mastication, depolymerization by heat and oxidation on the magnitude of the light refractive exponents of rubber and gutta-percha shows that there are characteristic differences between the two kinds of hydrocarbons, at least as far as the initial stage of oxidation is concerned. 4. From the purely practical and laboratory-testing points of view, it is possible to detect quickly and easily differences in the same kinds of raw rubber which are originally present or result from mastication, and to follow the course of mastication. 5. Furthermore it appears possible to draw conclusions regarding the constitution of rubber and gutta-percha hydrocarbons from differences in their viscosimetric and osmotic behavior. Accordingly the refractometry of rubber and gutta-percha hydrocarbons may furnish a new way of gaining a deeper insight into the structure of these natural substances.
The Problem of Changes in Rubber Brought about by Atmospheric Oxygen
Authors: Dufraisse Charles 
Published: February 2011

Abstract
Returning now to an earlier subject, let us ask in what way the conversion of rubber to fatty substances differs from plasticization by milling. Both originate in the same way, i. e., by the action of oxygen, and both are similar in appearance and in effects. To distinguish the two phenomena, one must resort to an arbitrary point of view, viz., that one phenomenon is spontaneous, whereas the other is induced. One is harmful, the other is advantageous, but fundamentally, whether advantageous or disadvantageous, they are nothing more than one and the same change in the rubber. Whether the change is an advantage or a disadvantage depends upon when it happens and upon its extent. This will explain why milling is such a critical operation and is so difficult to control. Because plasticization is a conversion to fatty substances, which is stopped at the right time, the operations involved in practical milling are a delicate and dangerous process, a process the effects of which are attained not in years or even in months but in minutes. The least miscalculation, and disastrous results may be obtained. Without entering into detail, it may be asked how many irregularities hitherto unexplained are from this time on readily explainable. The success of mastication depends upon peroxides, neither the quantity nor the behavior of which have so far been controlled, and even the existence of which has not until recently been suspected. It is a surprising fact that everything has always taken place in the desired way, particularly since to add to the complexity of things, the formation of peroxides itself depends upon electricity, and worse still upon the most changeable or capricious form, static electricity. Without suspecting it, one requires of a mixing mill that it perform the function of a generator of static electricity. Mixing is then at the mercy of influences which hinder the output of static machines, and it depends to some extent upon all kinds of indefinite factors, such as the state of the atmosphere, the temperature, the humidity and surface effects, not to mention the mixing mill itself, where nothing has been planned in advance to promote the unforeseen action. Henceforth, with a knowledge of the mechanism of mastication, it is going to be possible to improve the various factors playing a part, and it does not require a great prophet to foresee within a short time a profound change in this century-old technique.
The Elastic Behavior of Vulcanized Rubber
Authors: Hencky H. 
Published: February 2011

Abstract
As a consequence of the work described the author arrives at the conclusion that in the deformation range from 0 to 270 per cent only one elastic constant is needed for a full mathematical description, and that this constant is the modulus of shear defined for infinitely small deformations. If models could be made of rubber at less expense, this material could be used for the integration of the equations of elasticity. The solutions could be easily corrected for the lack of compressibility and for the change in the common law of elasticity.
Heat Treatment of Vulcanized Rubber
Authors: Fujiwara Takeo , Namiki Toshio 
Published: February 2011

Abstract
By heating samples of a rubber—sulfur system at 160° C., the following results in relation to the time of heating were obtained: 1. The maximum acetone extract was obtained after 0.5–1 hour of heating, and the amount decreased rapidly thereafter with increase in the time of heating until it became equal to or less than that of the control samples. 2. The maximum chloroform extract was obtained after 0.5 hour of heating, beyond which the amount decreased rapidly until it was less than that of the control samples. 3. The amount of total sulfur decreased, and this tendency to decrease is to be attributed to three factors. 4. There was also a rapid decrease in free sulfur. 5. The maximum combined sulfur content was reached after a certain time of heating, beyond which it decreased. The maximum point was reached after the acetone and chloroform extracts had reached their maximum values. 6. The maximum content of resinous substance was also obtained after a certain time. 7. The weights of the samples increased during the heating, and this increase was greater in over-vulcanized samples. A general discussion of these experimental findings leads to the conclusion that the processes of aging and reclaiming of rubber may both be attributed to a change in the chemical structure of the rubber molecules produced by heat in the presence of sulfur and oxygen. This investigation is an outcome of our work on reclaimed rubber. Thanks are due to Prof. Y. Tanaka for his kindly advice.
Plasticity Measurements in the Rubber Industry
Authors: Behre J. 
Published: February 2011

Abstract
With the growing realization of its importance in factory operations, the plasticity of raw rubber and rubber stocks is being studied more and more. As far as can be seen from the literature, four methods for measuring plasticity are known up to the present time. The most commonly used apparatus is probably that developed by Williams, which depends upon measuring the change in the thickness of rubber under a load. The same principle is followed in the recently published method of Karrer, except that in this case the elastic recovery is also measured. The other two methods, which were used first by Marzetti and by Griffith, depend on the other hand upon a wholly different principle. Here the rubber or the rubber mixture is extruded through a narrow opening under high pressure and the quantity extruded is measured. Griffith used a dead weight whereas Marzetti used compressed air to produce the pressure. For several years the author has worked with an apparatus constructed according to the Marzetti principle, and the present paper deals with experiments with this apparatus.
The Surface Properties of Rubber
Authors: Vellinger E. 
Published: February 2011

Abstract
It is known that the properties of rubber depend in large measure upon the nature of the ingredients which are compounded with it. Certain facts seem to show the enormous effect on the mechanical properties of rubber of surface forces which intervene between the rubber and the filler. In order to study the influence of this factor, the surface activity of the rubber was investigated in the present work. This activity was determined by measuring the lowering of the interfacial tension between a benzene solution of rubber and aqueous solutions of electrolytes by the tensiometer method of le Comte du Noüy, following a technique already described by the author and Weiss for measuring the interfacial tension of mineral oils.
Rubber Vibration Insulators. Some Characteristic Properties and Tests
Authors: Abbott Franz D. 
Published: February 2011

Abstract
Insulating of vibrating parts of engineering devices and structures is one of the vital problems of this age. The original purpose of carriage and automobile tires was, as indeed the major purpose of their use today still is, the suppression and elimination of shocks and vibrations during travel. This is true in spite of the importance of the “increased mileage” obtained by the use of rubber tires—a factor of no mean importance. This purpose is not so self-evident in the case of belting, hose, rubber-covered rolls, etc., where flexibility and/or elasticity are apparently prime requisites, but nevertheless the interception and safe-transmission of impulses or stresses with a minimum of vibration and noise are certainly of inestimable value. The use of rubber parts elsewhere in the automobile and general engineering field is unquestionably solely for the suppression or elimination of vibration. Recognition of the importance of rubber parts for such service came with the organization early in 1927, at the request of the Society of Automotive Engineers, of a committee to make a study of the most important characteristics of rubber necessary in such service and finally to set up standards of tests for these properties. This committee was formed by the American Society for Testing Materials and is composed of a number of the leading automotive engineers of the country and rubber technologists from the leading rubber companies. The S. A. E. also has an official representative. The scope of the work of this committee includes hardness testing, deflection under compression and compression-set (cold flow), resistance to cold, and dynamic fatigue, but to date its active efforts have been confined largely to the first two. The trend toward the use of rubber vibration insulators in railway work, both between ties and rails and in the cars themselves, is opening up a virgin field of enormous importance, and certainly shows the importance of these properties and the necessity for standardized tests. Of course, good aging qualities, resistance to abrasion, oil and heat, and relatively high tensile, shear, cutting and tearing strengths are important in the life of the part (but to varying degrees depending on the service intended). In addition, a standardized test for the adhesion of rubber to metal is now imperative. At present most specifications for motor supports in which rubber is bonded to metal require a direct pull, perpendicular to the metal-rubber interface, of 250 lbs. per sq. in. minimum, with actual values ranging up to over 1000 lbs. per sq. in.
Acetylene Polymers and Their Derivatives. V. The Polymerization of Bromoprene (Third Paper on New Synthetic Rubbers)
Authors: Carothers Wallace H. , Kirby James E. , Collins Arnold M. 
Published: February 2011

Abstract
The polymerization of bromoprene is closely analogous to that of chloroprene, but somewhat more rapid. Spontaneous polymerization yields as the final product μ-polybromoprene, which resembles vulcanized rubber but is more dense than rubber or μ-polychloroprene. A plastic (α) polybromoprene is readily isolated from partially polymerized bromoprene, and it is converted to the μ-product by the action of heat. At elevated temperatures in the presence of inhibitors a volatile liquid (β) polymer is formed. ω-Polybromoprene, a granular, insoluble, rubber-like mass, is produced under conditions that lead to very slow polymerization.
The Preparation and Crystallization of Pure Ether-Soluble Rubber Hydrocarbon: Composition, Melting Point, and Optical Properties
Authors: Smith W. H. , Saylor Charles Proffer , Wing Henry J. 
Published: February 2011

Abstract
Substantially all of the chemical and physical evidence concerning the nature of rubber is consistent with the chemical formula (C5H8)x, and this is the generally accepted formula for “rubber hydrocarbon.” An examination of the evidence discloses, however, that the above formula is not the only one which is consistent with this evidence. The difficulty of establishing beyond question the chemical composition of rubber hydrocarbon has been due largely to the lack of efficient physical methods for fractionating the hydrocarbon, of proving that the final fractions are one-component systems, and of chemically identifying these fractions. If, as seems not improbable, rubber hydrocarbon is a mixture of closely related hydrocarbons not all of which can be represented by the formula (C5H8)x, no single method of fractionation can be relied upon to separate this mixture into its constituents. The only methods heretofore available for this purpose have been those based upon extraction with different liquids and fractional precipitation. One of the most powerful methods for fractionating a mixture of hydrocarbons is systematic crystallization, and the purpose of this investigation was to develop a technic for applying this method to rubber.
A Method for Measuring Quantitatively the Swelling of Vulcanized Rubber in Organic Liquids by Means of a Voluminometer
Authors: van Wijk D. J. 
Published: February 2011

Abstract
1. A voluminometer for the study of the swelling of rubber is described, which may also be used for other substances, e. g., wood, gelatin, artificial silk, and similar materials. 2. The advantages of this apparatus are: (a) Swelling determinations with satisfactory precision can be carried out over longer periods of time than is the case with ordinary methods. (b) The accuracy of the apparatus is greater than with the direct weighing method or with direct dimensional measurements. (c) The procedure is extremely simple and rapid. 3. Typical results of practical swelling determinations at 20° C. and 30° C. are shown. The swelling curves derived from the data obtained agree with the investigations by Scott.
Reactions during Vulcanization. III. The Multiple-Accelerator Effect
Authors: Jones H. C. 
Published: February 2011

Abstract
Diphenylguanidine functions as an activator for mercaptobenzothiazole when the two accelerators are compounded in a stock deficient in fatty acids. Diphenylguanidine functions as an accelerator when compounded with mercaptobenzothiazole in a stock with a normal fatty acid content. Butyraldehyde aniline in conjunction with mercaptobenzothiazole behaves in the same manner as diphenylguanidine. Within the limits investigated, the amount of soluble zinc available for reaction has a direct bearing on the ultimate tensile strength of diphenylguanidine and mercaptobenzothiazole stocks.
Determination of Rubber in Rubber-Bearing Plants
Authors: Spence D. , Caldwell M. L. 
Published: February 2011

Abstract
THE determination of the true rubber content of both raw and manufactured rubber has been the subject of extensive investigation. Search has failed to reveal any corresponding record covering studies applicable to rubber-bearing plants. The authors' investigations, covering such methods as have been published, demonstrate their inaccuracy and inadequacy for practical use. There has never been published, as far as the authors have been able to determine, any thorough, systematic study of the factors which determine the value and accuracy of any method for the quantitative determination of the pure caoutchouc contained in a given specimen of plant tissue. The work embodied in the present communication was undertaken as an essential step towards the solution of some of the complex problems in the production of rubber from the guayule shrub. Without some method for determining with completeness and accuracy in terms of pure caoutchouc the value of any given sample it would have been fruitless to proceed to studies of the metabolism of the plant. The equally important problems in the control of commercial operations, both in field and factory, hinged at the outset on the development of an accurate means to determine the rubber content of the plant.
New Machine for Laboratory Evaluation of Fatigue of Rubber Compounds Flexed under Compression
Authors: Cooper Leslie V. 
Published: February 2011

Abstract
THE failure of rubber compounds to resist fatigue when subjected to flexing under compression, or their tendency to “blow-out,” has always been a serious problem, and is becoming an even greater limiting factor in all phases of rubber technology. A new machine has been developed recently in the laboratories of The Firestone Tire and Rubber Company for the measurement of fatigue resistance of rubber compounds. Previous machines of this type have usually been large wheels or drums on which whole tires have been run to destruction; The laboratory machines have not been very numerous or very successful. The Schopper detrition tester (2) is a laboratory machine for testing the fatigue and abrasion resistance of rubber stocks in the shape of small balls. Abbott (1) obtained blow-outs in his laboratory work on testing rubber used to absorb vibration. Many suggestions have been advanced as to how correct laboratory evaluation of fatigue resistance might be accomplished. The design finally adopted (Figure 1) was made up by Raymond W. Allen, of the Firestone engineering staff, in whose name the patent application on this Flexometer has been made.
The Problem Whether Litharge Is an Antioxygen or a Proöxygen toward Rubber. The Practical Consequences
Authors: Dufraisse Charles , Drisch Nicolas , Pradier-Gibello Denise 
Published: February 2011

Abstract
In work which was the subject of an address before the second International Congress of Rubber Technologists we were surprised to find that the oxidation of rubber is accelerated by litharge, in view of the fact that this product has the reputation of protecting rubber against attack by atmospheric oxygen, at least during vulcanization, where in its presence it is possible to operate in hot air. Comments made to us at that time by several technologists, as well as our own ideas, led us to undertake a more detailed study of this phenomenon. Later systematic experiments were undertaken, and these were the subject of two brief communications. The present paper covers the complete series of researches.
Investigation of the Aging Processes of Rubber. II. The Gold Reaction of Products of the Initial State of Oxidation
Authors: Dogadkin B. , Balandina W. 
Published: February 2011

Abstract
1. Aqueous extracts of pale crepe, which were exposed to the radiation of a quartz lamp or which were masticated for a short time on cold mills, reduce slightly alkaline gold chloride solution with the formation of colloidal gold. 2. The maximum intensity of the gold reaction under the experimental conditions described lay within the limits of 20–30 minutes' exposure to radiation. 3. The maximum intensity for smoked sheets lies within the same range; however even before irradiation this rubber yields an extract which reduces gold chloride. 4. The electric conductivity of aqueous extracts increases continuously, and under the experimental conditions described began after 30 minutes of irradiation of the rubber. 5. The character of the variations in the intensity of the gold reaction and the electric conductivity of the extracts must be explained on the basis of corresponding concepts of the chemistry of changes in rubber during aging.
Estate Practice and Its Relation to Factory Requirements
Authors: Jones F. B. 
Published: February 2011

Abstract
In spite of continuous investigation of the problem of the variation in supplies of raw rubber, a completely satisfactory method of dealing with the matter has yet to be devised. Before discussing estate practice it is necessary to agree what the desirable properties of raw rubber should be. It is perhaps a surprising fact that rubber manufacturers are not in complete agreement. There seem to be two schools of thought. One school considers quick-vulcanizing and high-tensile rubbers to be preferred, while the other favors a slow-vulcanizing and easily worked raw material. The most desirable properties in raw rubber from the factory point of view are uniformity, ease in handling, and a high level of quality in the finished product. Uniformity must come first. If the properties of raw rubber are known to be consistent, a standard manufacturing process can be confidently adopted and followed. Nowadays the ability to repeat operations exactly is so important from a factory efficiency point of view that variability in raw material is much more important than the actual properties of that material, assuming of course a reasonable level of quality.
The Antioxidants of Rubber Latex. I.
Authors: Bondy H. F. , Lauer G. G. 
Published: February 2011

Abstract
Various authors have observed that raw rubber from which the acetone-soluble portions have been removed deteriorates much more easily than does crude raw rubber itself. It is certain that this deterioration is associated with an autoöxidation of the rubber. In this laboratory it has been proved in different ways that sheets of crude rubber may lie in the air for years without any change. On the contrary, rubber which has been purified according to Pummerer's method is extraordinarily sensitive to oxygen. If such a purified rubber lies in the air for a couple of days it loses its elasticity, becomes tacky and short, and finally becomes completely fluid. Accordingly there must be a substance in natural rubber which prevents the autoöxidation of the hydrocarbon, or at least retards it greatly. The object of the present work was to identify this substance, to isolate it, and to explain its constitution and its mode of action if possible.