bluuebunny/crossref_metadata_2025_split huggingface dataset:
Applications of Ultraviolet Spectrography. A Study of the Transformations Which Tetramethylthiuram Disulfide Undergoes during the Vulcanization Process
Authors: Jarrijon André 
Published: February 2011

Abstract
Various experiments make it clear that the method of spectrographic determination can be applied to a complicated case where the product to be determined does not remain intact in a mixture but is transformed into some other compound. Furthermore the results obtained, which were confirmed by chemical tests, are definite and precise enough to make it possible to determine the type of transformation which takes place in rubber when tetramethylthiuram disulfide is used as a vulcanizing agent. The liberation of sulfur is only an accessory reaction, in fact there is probably not even any such reaction. More probably there is a dehydrogenation of the rubber, without liberation of hydrogen sulfide, a dehydrogenation which involves perhaps certain restricted parts of the molecule, e.g., the extremities of the chains, as has been suggested by Boggs and Blake. It is possible to conceive various schemes whereby this dehydrogenation may take place and which would make it possible to explain at the same time the formation of zinc dimethyldithiocarbamate, the decrease in unsaturation found by Hauser and Brown, and the fixation of a certain amount of sulfur on the rubber.
The Terminology of Intrinsic Viscosity and Related Functions
Authors: Cragg L. H. 
Published: February 2011

Abstract
The confusion existing in the use of symbols and names for Kraemer's “intrinsic viscosity” and other functions related to it is illustrated and deplored. The reasonable plea is made that one name be adopted for each function and that it be used with no other meaning. To stimulate discussion and ultimate action, the following names are proposed: “specific viscosity” for ηsp; “reduced viscosity” for ηsp/c, “inherent viscosity” for (ln ηr)/c; and “intrinsic viscosity” for [η], whether determined as “limiting reduced viscosity” limc→0 (ηsp/c), or as “limiting inherent viscosity” limc→0 (ηr/c), or as “limiting viscosity concentration coefficient” limc→0 (dηr/dc). Often, especially in routine practice, it is the relative kinematic viscosity νr, that is determined ; unless this is shown to be numerically equal to the relative viscosity ηr, the symbols and names of the derived functions should be modified accordingly: thus, (ln νr)/c inherent kinematic viscosity, [ν] intrinsic kinematic viscosity. Frequently, also, kinetic energy corrections are neglected; under these circumstances the suggested usage is tr, relative flow time, tsp/c reduced flow time, [t] intrinsic flow time, etc.
The Theory of Permanent Set at Elevated Temperatures in Natural and Synthetic Rubber Vulcanizates
Authors: Andrews R. D. , Tobolsky A. V. , Hanson E. E. 
Published: February 2011

Abstract
Certain materials, including natural and synthetic rubbers, after being deformed for finite periods of time and then released, do not return completely to their original dimensions. This phenomenon is called “permanent set”. There are many different types of measurements, made under a great variety of conditions, all of which are described as measurements of permanent set. The molecular causes of permanent set are not the same under all of these conditions. For this reason we shall restrict ourselves in the present article to a discussion of the permanent set taking place in thin rubber samples which are maintained at constant extension at elevated temperatures. We shall show that the permanent set which occurs under these conditions is due to chemical changes which affect the structure of the rubber network, and that a quantitative molecular description of permanent set can be accomplished by the use of concepts already developed concerning the nature of these deteriorative chemical processes.
Tackiness of GR-S and Other Elastomers
Authors: Busse W. F. , Lambert J. M. , Verdery R. B. 
Published: February 2011

Abstract
The analysis of tackiness shows that it is a complex property which depends on a balance between a large number of different factors, including the geometry of the sample as well as the surface forces and the visco-elastic properties of the material itself. The quantitative measurements of the effect of the rate of removal on the apparent tackiness of pressure-sensitive adhesive tapes show that significant differences are found at very slow removal rates (105 seconds per cm.) which do not show up at much higher removal rates (10 seconds per cm.). These differences may affect the performance of the tapes in service. A simple quantitative test is described which can be used to study the effects of various processing treatments and various softeners, tackifiers and other compounding ingredients on the tackiness of GR-S and other rubbers. Koresin was the most effective tackifier found for GR-S. The authors wish to acknowledge the continued interest of W. E. Hanford, Director of the Laboratory, and the helpful discussions of tackiness measurements with C. E. Schildknecht. Miss Ruth Sellers and Miss J. L. Nuver helped in taking much of the data. The first Koresin samples were prepared in the laboratory by C. E. Schildknecht and A. O. Zoss before the commercial material was available.
Evaluation of the Physical Properties of Rubber Vulcanizates at Low Temperatures
Authors: Mullins L. 
Published: February 2011

Abstract
The technical importance of rubber vulcanizates in fields where they are likely to be subjected to temperatures lower than normal requires no emphasis, and has resulted in considerable activity being directed to the evaluation of the physical properties of rubber vulcanizates at such temperatures. The purpose of these investigations has been to compare the low temperature serviceability of various rubbers, and to study of the behavior of the materials at these temperatures in order that the data obtained may be used to assist design. Such extension of knowledge is of great importance since rubber vulcanizates exhibit considerably increased stiffness and become brittle at low temperatures. Several good summaries of the work exist in the literature; these show that there is a considerable lack of uniformity in the methods of testing and representation. As a result of this wide diversity of test methods, there is no generally accepted index of low-temperature serviceability. Many of the tests which have been used involve the extension of the usual technical tests to lower temperatures, whereas others involve a study of the performance of rubber components in conditions of service. The results of such tests generally have been quoted as a temperature below which a particular property fails to fulfil a given requirement. The endeavor to obtain one temperature or one parameter which characterizes the resistance to low temperatures has been only partially successful, since the interdependence of stress, strain, time and temperature make it impossible to formulate relations of a simple character which describe the behavior of rubber vulcanizates over even a limited range of conditions. First, there is the need for an accepted standard test (or tests) ; secondly there is the need for a convenient method of expressing the resistance to low temperatures, and lastly, there is the need for the development of the ideas of the processes leading to the changes in physical properties at low temperatures. In this paper it is intended to review the various methods which have been suggested for low-temperature testing, to indicate the sources of the inadequacy of the individual tests, and to describe the initial results of an investigation, as yet incomplete, into a convenient means of testing and representing the mechanical properties at low temperatures.
A Study of the Rubber-Metal Bond
Authors: Buchan S. , Shanks J. R. 
Published: February 2011

Abstract
Although the practice of bonding rubber to metal has been in use for many years, no theories appear to have been advanced which explain adequately the mechanism of bonding. It has been stated that the brass bond between rubber and metal functions through chemical linkages, but this can only be regarded as tentative and has yet to be proved. No attempt has been made to find out how ebonite functions as a bonding medium or the more recently discovered derivatives of rubber, such as sulfonated rubber, chlorinated rubber, and rubber hydrohalides. Until it is properly elucidated just how bonding agents do act, further logical development of improved bonding media cannot be pursued. It is intended in this paper to show how the rubber-metal bond behaves at subnormal temperatures and how a low temperature technique may be used for studying the mechanism of bonding. The effect of low temperatures on the tensile strength and associated properties of vulcanized rubber, such as hardness, permanent set, flexibility, resilience and flexing, has been dealt with fairly comprehensively in the literature. Progressive reduction in temperature leads to only a moderate increase, for example, in tensile strength, until the point is reached at which the rubber stiffens and freezes, when a marked increase occurs. Examination of a brass-bonded unit at low temperatures revealed that the graph obtained for bond strength was very similar in slope and character to that for tensile strength. The similarity is illustrated by the data in Table 1 and in Figure 1.
The Sensitive Detection of Organically Combined Bromine
Authors: Kirchhof F. 
Published: February 2011

Abstract
When a few drops of concentrated copper sulfate solution are added to a concentrated solution of potassium bromide, this solution turns yellow or brownish. When it is warmed, the color darkens, and on cooling or by dilution it becomes light again; finally at a definite concentration the color becomes yellow-green. If a drop of the concentrated solution is placed on chemically pure filter paper and is allowed to dry, a bright or dark purple-red color is obtained, the shade depending on the method of drying. This color appears even when drying is at room temperature; it becomes paler when one breathes on the sample, and disappears completely when the colored spot is moistened with water, but on drying reappears as a pale rose color, the intensity of which depends on the concentration. The same purple color, but more brilliant, appears when a few drops of concentrated sulfuric acid are added to potassium bromide—copper bromide solution. In this case the color is extraordinarily intense, and it is visible even when only 0.5 mg. of bromine per liter is present.
Chemical Structure of Vulcanized Rubber
Authors: Brown J. R. , Hauser E. A. 
Published: February 2011

Abstract
A CENTURY ago, Charles Goodyear in America and Th. Hancock in England found that the properties of crude rubber could be greatly improved by heating it with sulfur. The product resulting was more elastic, more resistant to tear and abrasion, less affected by solvents, and decidedly less thermoplastic. The treatment of rubber to give these desired properties is known generally as vulcanization and must be considered as the basis for the enormous growth of the rubber industry and the extensive use of rubber products in our everyday life. Broadly speaking, vulcanization involves the reaction, in some fashion, of sulfur with rubber. Extensive investigation has revealed other substances, such as benzoyl peroxide or polynitrobenzenes, which can transform rubber into a “vulcanized” condition. Experience has also shown that metallic salts of zinc or lead and especially certain organic compounds called “accelerators” greatly affect the rate of vulcanization, and these are favorably employed in practice. A vast amount of empirical knowledge has been gained which has greatly improved the practical application of vulcanization and the quality of rubber products, but which has failed as yet to reveal a complete picture of the true nature of the process.
The Permeability of Organic Substances to Water
Authors: Badum E. 
Published: February 2011

Abstract
Although organic substances are in the ordinary sense regarded as waterproof, actually they are somewhat permeable to water vapor, and this permeability is sufficient to render them inapplicable as covering or sheathing for cables. In view of this, it was decided to study in a quantitative way the phenomenon of permeability to water of organic substances. The method chosen for making these measurements and the results obtained are described in a brief way in the following paragraphs. The first measurements were made with an apparatus which consisted of a hemispherical bell jar, the open part of which was carefully sealed by a sheet of the substance to be tested. To this bell jar was attached, by a ground-glass connection, a tube which could be closed by a stopcock, and which contained phosphorous pentoxide. In this way the vapor pressure of water within the bell jar was maintained at zero. The small apparatus was suspended in a constant-temperature chamber saturated with water vapor. The increase in weight of the weighing tube containing the phosphorous pentoxide was a measure of the amount of water which diffused through the sheet being tested.
Mastication of Rubber a Study of Some of the Oxidation Rocesses Involved
Authors: Busse W. F. , Cunningham E. N. 
Published: February 2011

Abstract
The rate of breakdown of smoked sheet, pale crepe, and sprayed-latex rubber in a laboratory internal mixer is a minimum at temperatures around 240° F., and the rate may be increased as much as four- or five-fold by either raising or lowering the temperature 80° F. The high-temperature reaction (above 240° F.) probably is similar to the thermal oxidation which occurs when rubber is heated in air, since the rates of both reactions are increased by increasing the oxygen concentration, and they are reduced by adding antioxidants. The low-temperature reaction (below 240° F.) may involve a mechanical acti-vation of the rubber, as in milling. The rate of this reaction first increases and then remains constant or decreases slightly as the oxygen concentration in the temperature during mastication is increased from about 0.5% to 20% to 100%. Some nitroso compounds are powerful stiffeners of rubber, and they change the softness-retentivity relation, making it more like that of reclaim or semi-vulcanized rubber. The effect of most commonly used “softeners” on the plasticity of rubber is small compared with the effect of changing the mastication temperature ±40° F. Exceptions to this are certain vulcanization accelerators (at high temperatures), hydrazine compounds and thiophenols, which appear to be true mastication acelerators or oxidation catalysts.
A Relationship between the Critical Oxidation Potentials and Antioxidant Activities of Rubber Antioxidants
Authors: Doede C. M. 
Published: February 2011

Abstract
1. According to the data presented, all of the compounds tested which exhibit marked antioxidant activity have an Ec value between 0.65 volt and 0.90 volt. Many substances exist which have an Ec value within the optimum range, but do not have much antioxidant activity. The condition that the Ec value for a good antioxidant falls between 0.65 volt and 0.90 volt seems to be necessary but not sufficient. 2. A value of Ec within an optimum range seems to be only one of several possible physico-chemical phenomena which govern the rubber antioxidant activity of a compound. 3. The determination of the Ec value of a compound should not be used as the sole criterion of that compound's antioxidant activity.
Dielectric Measurements in the Study of Carbon Black and Zinc Oxide Dispersion in Rubber
Authors: Kemp A. R. , Herrmann D. B. 
Published: February 2011

Abstract
The dielectric constant, power factor, conductivity and d.c. resistivity of rubber compounds containing various types and quantities of zinc oxide and carbon pigments have been measured. It has been shown that the dielectric properties of rubber compounds having high loadings of zinc oxide depend on the particle size and purity of the zinc oxide used. The French process oxides with the smallest particle size were found superior to other grades. Water-soluble impurities in zinc oxide are shown to have a deleterious effect on dielectric properties, especially in the presence of moisture. The effect on dielectric properties of adding carbon black to a rubber compound has been shown to be dependent on the type and amount of black added, and on the nature of its dispersion in the rubber. The dielectric properties of rubber compounds containing “soft” black made by the thermal decomposition process are shown to be distinctly superior to, and widely different from, those of the same compounds containing equal amounts of channel process black. The general conclusion has been reached that the smaller the particle size and the better the dispersion of carbon pigments in the rubber, the greater will be the increase in the dielectric constant and conductivity, and the greater will be the decrease in resistivity.
The Testing of Rubber at Low Temperatures
Authors: Carrington J. H. 
Published: February 2011

Abstract
Developments in modern compounding have in the last few years undoubtedly improved the general properties of vulcanized rubber. Ever-widening fields of application of rubber goods have extended the range of temperature over which rubber is expected to retain its properties. The search for rubber compounds that shall have greater resistance to oxidation, heat, oil and so forth has certainly been pushed forward with great success, but progress in the other direction, namely, towards rubber compounds resistant to extreme cold, does not appear to have been so rapid. In this country we do not experience the extreme cold which occurs in the upper atmosphere and in regions nearer the poles, but rubber suspension systems, etc., as used in ships in polar latitudes or vessels transporting foodstuffs, railway components of many kinds and the numerous rubber parts used in the construction of aircraft all suffer to some extent from loss of resilience when exposed to cold conditions. It therefore seems just as necessary to compound with a view to resisting changes induced by freezing as we normally do to resist heat. With this end in view it was decided to make a critical review of published data on the effect of low temperatures on rubber to serve as a guide to further practical work. As is to be expected, those countries experiencing great cold have already carried out considerable investigation, but the available information is fairly widely distributed, and no doubt there is much work of a private nature which has never been published. It will be convenient, in the summary which follows, to indicate the most important information under headings relating to the chief properties of rubber. As is so frequently the case, physical results have been obtained on mixings of unstated composition or state of vulcanization, or on mixings that are simple, no doubt, from the theoretical standpoint but almost unusual from the practical point of view.
Some Properties of Two Vulcanized Pure Gum Compounds at Low Temperatures
Authors: Somerville A. A. 
Published: February 2011

Abstract
(1) High and normal sulfur pure gum compounds became board-like and brittle within a few minutes when cooled at −60° C, yet when tested at this temperature they had an elongation of over 500% and tensile strength of over 5,000 lbs. per sq. in. (2) With decreasing temperature the two compounds gave increasing tensile strength and modulus and decreasing elongation. (3) Relatively high combined sulfur, i. e., up to over 8% on the rubber, was accompanied by a marked increase in hardness, even at temperatures no lower than −30° C. (4) A substitution of deproteinized rubber for smoked sheet appeared to give greater resistance to hardening at temperatures down to −40° C. (5) Unvulcanized, unmilled smoked sheet showed greater resistance to hardening on rapid cooling than the vulcanized compounds at all temperatures tested. This phenomenon, however, is not to be confused with that of ordinary frozen rubber, which is commonly observed at temperatures above −30° C.
Static and Dynamic Properties of Rubber under Compression
Authors: Kosten C. W. 
Published: February 2011

Abstract
Rubber undoubtedly possesses a number of unique properties which make it a particularly suitable accessory material for constructional purposes; e. g., in elastic mountings, elastic couplings and dampers against torsional vibration on driving shafts. Its application to such uses, however, requires knowledge of other than the usual properties. Most of these are related to simple physical quantities such as modulus at a given elongation, hysteresis, permanent set and the like. In § 2 will be discussed magnitudes that may be entailed in the cases in question. Relations existing between the various magnitudes will come up for consideration in the course of the discussion. Most of the problems involved have already received some attention. Some of the more important investigations into this subject will be dealt with in § 3. Finally, the results of experimental work on the static and dynamic behavior of rubber under compression will be recorded in § 4.
Dynamic Evaluation of Damping and Durability of Rubber Compounds
Authors: Roelig H. 
Published: February 2011

Abstract
The method described in this paper makes possible the dynamic evaluation of rubber and rubber-like compounds. It allows the measuring of the dynamic damping (hysteresis) loop during the fatigue test, and may be applied not only to small rubber samples but to larger objects such as vibration absorbers and whole tires. The apparatus renders valuable service in developing compounds of natural and synthetic rubber that undergo dynamic stress.
The Use of the Pendulum in Rubber Testing
Authors: Jones F. B. , Pearce W. H. 
Published: February 2011

Abstract
During the past few years considerable interest has been shown in the use of pendulum methods for the study of resilience properties of rubber compounds. We feel therefore that an account of the development and use of the pendulum method in the Dunlop Rubber Co.'s laboratories will prove of general use. In this country the period from 1918 witnessed a rapid extension in road transport, carried at that time almost exclusively on solid tires. With this development the performance of heavy vehicles improved considerably and tires were operated under the increasingly severe conditions, both with respect to speed and load. It is well known, that if a solid tire is operated under sufficiently severe conditions it is no longer able to dissipate the heat developed within it, and its temperature rises until eventually an explosion or the familiar “blow-out” occurs. This phenomenon, of course, results from the fact that rubber is not perfectly elastic. When transmitting energy it does not release all the energy supplied to it. Some of the energy is always absorbed and appears in the rubber in the form of heat; the faster the energy is supplied, the greater is the increase in temperature.