bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distribution of Oxygen in Oxidized Rubbers
Authors: Naylor Ralph F. 
Published: February 2011

Abstract
It has been fairly well established that the initial products of the auto-oxidation of polyisoprenes are hydroperoxides. The course of subsequent reactions is not, however, so clear. Under normal conditions the peroxides are unstable, and give rise to a large variety of secondary oxidation products. The object of the present work is to study the distribution of oxygen in the various groups which have resulted from these secondary reactions. The course of oxidation.—Oxidative fission of the double bond of an isoprene unit may be expected normally to give rise to a carbonyl and an aldehyde group, and the latter may be further oxidized to carboxyl. The hydroperoxide groups which effect this oxidation are, as experience shows, mainly reduced to alcohol groups. Epoxides may result from transference of the active oxygen from the peroxide groups to the olefinic bonds, and esters and ethers by subsequent reactions of the alcoholic groups. Thus any or all of the following functional groups may be expected to be present in an oxidized rubber:
The Dependence of Damping and Dynamic Modulus on Temperature as a Means of Evaluating the Elastic Behavior of Raw and Vulcanized Rubber. The Dynamic Resistance of Soft Rubber to Cold
Authors: Roelig H. 
Published: February 2011

Abstract
The dependence of the damping and elastic modulus of a vuleanizate on its temperature makes it possible to evaluate its elastic behavior throughout the temperature range which is of technical importance. Measurements were carried out at a constant frequency of 16⅔ Hertz units (1) to determine the damping effect, in which case the freezing temperature of the vulcanizate, the maximum damping above the freezing point, and in many cases the decrease in damping with increase in temperature above 0° C, were determined, and (2) to determine the elastic modulus, in which case the freezing temperature of the vulcanizate, the freezing range, and the dynamic modulus of elasticity were determined.
Structural Changes in Vulcanization of Buna-S
Authors: Keck Max H. , Cheyney La Verne E. 
Published: February 2011

Abstract
In conclusion, the data presented here indicate that two types of chemical reactions take place during the vulcanization of Buna-S stocks of a specific type: (1) a combination with sulfur, which may or may not involve the double bonds in the polymer, and which may be similar in character to the primary vulcanization reaction of natural rubber; (2) a second reaction, presumably polymerization, which accompanies the first and is related to and possibly initiated by it, and which continues on over cure.
Effect of Pressure on the Melting of Crystalline Rubber
Authors: Wood Lawrence A. , Bekkedahl Norman , Gibson Ralph E. 
Published: February 2011

Abstract
The effect of hydrostatic pressure on the melting of crystalline rubber has been the subject of a brief investigation extending to pressures above 1,000 atmospheres. With a particular sample of stark rubber, it was found possible to raise the temperature of meltings as determined by the disappearance of birefringence, from about 36° to 70° C by the application of a pressure of 1,170 bars (1,170×105 dynes per sq. cm.). The results, including observations at intermediate pressures, can be represented adequately by the equation: log10 (p+1,300)=5.9428−(875/T).
Effect of Moisture on GR-S Rate of Cure and Physical Properties
Authors: Rush Ian C. 
Published: February 2011

Abstract
Moisture has been discussed as a factor which may give rise to variable rates of cure of GR-S. This moisture may be present in GR-S itself or in the compounding ingredients used. Accordingly, a program was initiated in the spring of 1944 to establish the influence of moisture, not only on the rate of cure of GR-S, but also on its physical properties. Since that time two papers have been published on this subject by other investigators. The results reported here verify some of the conclusions drawn by these investigators but seem to be at variance with others. In this study various proportions of water were added in the following ways : by premixing with carbon black, by adding directly on the mill rolls at the completion of normal milling, and by soaking GR-S crumb in water. Curing curves were obtained for each batch, and were used to evaluate the rate of cure. To eliminate day-to-day variations in physical properties due to error in testing methods, three batches of different moisture contents were mixed and tested on the same day. This same group was then remixed and tested on successive days until at least three batches had been tested for each moisture content and each method of addition. The averages of the individual results (stress-strain data and percentage moisture retained) on batches to which the same percentage of water was added, were then considered free from day-to-day variations.
Organic Analysis of Hevea Latex VIII. Development of a General Scheme of Analysis
Authors: Altman R. F. A. 
Published: February 2011

Abstract
An attempt is made in this work to show the desirability and the practicability of a complete analysis of Hevea latex. It has been found that fresh, unammoniated latex is the only trustworthy starting material for analysis. Difficulties encountered in the analysis are due principally to (1) the trouble-some property of the rubber hydrocarbon to adsorb, and hold firmly, the other components of latex; (2) probable chemical, enzymic, and bacterial changes, which cause great difficulties in the isolation of those components in the state in which they are originally present in latex, and (3) the lack of proven methods of quantitative separation of the various groups of organic compounds. In his attempt at an ideal method of analysis, the author, due to the above-named difficulties, is faced with the apparent impossibility, as yet, of separating the various components of latex quantitatively and in the original state in which they are present in the latex. As a result of much theoretical considera- tion and practical experience, gained meantime, the author has reached a method, the scheme of which is described in the present work.
Using The Mooney Viscometer
Authors: Buist J. M. 
Published: February 2011

Abstract
The increased use of the Mooney viscometer in America for checking the plasticity of different batches of synthetic rubber has led to a wider appreciation of the care which is necessary for accurate operation of this apparatus. A recent article dealt fairly fully with most of the factors affecting results obtained with the Mooney viscometer. Some results obtained on the instrument at Blackley are extremely interesting and publication may help other users to avoid the trap of using Vistanex for calibration purposes. Vistanex is a stable material chemically, which is essential for a standard material, but other factors overcome this advantage and preclude its use. The mechanical method of calibrating the machine checks the spring at readings 0 and 100 and as long as the spring is not taken beyond its elastic limit there is no point in checking intermediate values. Vistanex gives a reading of 50 when tested at 100° C in the standard manner. It has been assumed that if a reading of 50 is obtained with Vistanex, the instrument must be working correctly. This view is wrong.
The Proportion of Crystalline and Amorphous Components in Stretched Vulcanized Rubber
Authors: Wildschut A. J. 
Published: February 2011

Abstract
Determinations of the tension-temperature relation of stretched vulcanized rubber can provide us with data about the proportion of crystalline and amorphous components. The amount of crystalline material appears to be 30–32 per cent at 600 per cent elongation and at 20° C. An expression is derived relating percentage of crystalline material and temperature. The results are in close agreement with those of x-ray measurements carried out by Goppel, but diverge largely from those obtained by Field. The cause of this difference is not yet clear. Stretched vulcanized rubber consists of a predominating amorphous phase, with crystallites embedded in it. On stretching orientation occurs, and a systematic addition of secondary valency forces is possible. This is the main cause of the existence of a certain tensile strength. Crystallization, though important as an indication on orientation, is more or less an incidental phenomenon. The distance function of the secondary forces may be of equal importance with the orientation.
Stress-Time-Temperature Relations in Polysulfide Rubbers
Authors: Stern M. D. , Tobolsky A. V. 
Published: February 2011

Abstract
Polysulfide rubbers of various internal structures have been investigated by measurements of continuous and intermittent relaxation of stress and by creep under constant load at temperatures between 35° C and 120° C. Continuous stress relaxation measurements indicate that these rubbers obey approximately the simple Maxwellian law of relaxation of stress, which indicates that one definite type of bond in the network structure is responsible for stress decay. The activation energy for the relaxation process in each of the polysulfide rubbers is nearly the same, indicating that the same type of bond is responsible for the relaxation behavior of all the polysulfides investigated. In contrast to hydrocarbon rubbers, oxygen is not the cause of high temperature relaxation in polysulfide rubbers, nor does heating in air at moderate temperatures for times comparable to the relaxation time produce changes in physical properties as determined by modulus or by appearance of the samples. Several possibilities regarding the mechanism of the relaxation process and the type of bond involved are considered in the light of the experimental results.
The Influence of Milling on the Plasticization of Rubber
Authors: Haehl Adrien , Le Bras Jean 
Published: February 2011

Abstract
In the first part of this work, the influence of the temperature of the mill rolls and of their friction ratio on the plasticization of rubber was examined in a systematic way. The experiments described in this second paper had as their object the determination of the influence of the speed of the mill rolls, and comprise a series of measurements at three different temperatures, viz., 20°, 60° and 100° C. The machine and equipment were, as before, a Troester mill, each roll of which was equipped with a temperature control and a speed regulator. In addition a wattmeter made possible the recording of the power consumed by each of the motors. In general the operating conditions of the previous work, which were described in detail in the previous paper, were followed in the present work. (1) Rubber.—First latex crepe (from the same lot as that used in the first part of the work). (2) Mill rolls.—Diameter 20 cm. ; effective length 30 cm. (3) Spacing of the mill rolls.—When loaded, 1 mm. (4) Bank of rubber.—Diameter about 10 mm., which was held constant by decreasing the effective length of the rolls to compensate for successive withdrawing of samples. (5) Plasticity measurements.—Williams apparatus, with test-samples of 1 cc. volume.
Isothermal and Adiabatic Stress-Strain Curves of Vulcanized Rubber
Authors: Hauk V. , Neumann W. 
Published: February 2011

Abstract
The stress-strain diagram of rubber has been the subject of a large number of investigations, including those of Röntgen, Gough, and Joule in the nineteenth century, those on isothermal phenomena by Meyer and Ferri, and Wiegand and Snyder, and most recently those on adiabatic phenomena of Ornstein, Eymers, and Wouda. The investigations of Meyer and Ferri are concerned chiefly with the dependence of the stress-strain phenomena on the temperature, and they confirm experimentally the hypothesis that within a certain range of temperature and with highly vulcanized samples, the stress is proportional to the absolute temperature, i. e., S=aT+b. At lower states of vulcanization this proportionality does not hold true. The work of Ornstein and his collaborators, which is frequently cited in the literature, is concerned with the phenomena which take place when raw rubber and weakly vulcanized rubber are stretched adiabatically; that of Wiegand and Snyder is concerned chiefly with a thermodynamic interpretation of stress-strain curves obtained experimentally. Now in spite of the fact that stress-strain curves of rubber have been determined so frequently, particularly under isothermal conditions, these measurements are for the most part of limited value, since the chemical nature of the types of rubber employed is not described definitely. Then again in most cases little attention was paid to the difference between isothermal and adiabatic stretching. In view of these facts, it seemed desirable to throw further light on the problem by obtaining stress-strain curves of one particular well-defined material. The object of the present work was then: 1. To obtain true isothermal stress-strain curves as a function of the degree of vulcanization and as a function of the temperature, and thus to study stresses as a function of temperature. 2. To obtain data on the same vulcanizates under adiabatic conditions. 3. To compare the stress-strain results under isothermal conditions with those under adiabatic conditions.
Influence of Copper on Rubber. VII. Effects of Metallic Salts on the Evolution of Hydrogen Sulfide
Authors: Ōkita T. 
Published: February 2011

Abstract
It is concluded that maximum tensile strength is reached more quickly than normally when the amount of hydrogen sulfide increases above normal. If considerable acid is formed during cure, the amount of hydrogen sulfide evolved decreases, and curing is retarded. The heat-resisting properties are increased by addition of a salt which depresses the amount of hydrogen sulfide evolved. On the contrary, when much strong acid is formed, the deteriorating effect of the acid on the rubber becomes very great and the contrary result is obtained.
Application of Thermodynamics to the Chemistry of Rubber
Authors: Bekkedahl N. 
Published: February 2011

Abstract
The purpose of this paper is to show how thermodynamic data on rubber and related substances can be employed in studying and predicting their reactions. The method will be illustrated by the results of recent studies on rubber and iso-prene made at the National Bureau of Standards. These results enable us to predict the conditions which favor the polymerization of isoprene to form rubber, and also the conditions which favor the reverse reaction, the thermal decomposition of rubber to give isoprene. Rossini, in his review paper on “Modern Thermodynamics,” makes the following statement : “The ultimate end of chemical thermodynamics may be said to be the evaluation of the free energy of formation, from the appropriate fundamental units of matter, of every substance in all possible states….” Our chief object, then, for rubber is to obtain as accurately as possible the free energies of formation of rubber, sulfur, rubber-sulfur compounds and other forms of vulcanized rubber, isoprene and all other substances with which rubber reacts or from which it may be made.
Tackiness and Consistency of Rubber after Treatment by Alkali
Authors: De Vries O. 
Published: February 2011

Abstract
Our knowledge of the chemistry of tackiness in plantation raw rubber is still incomplete. We know that under different circumstances distinct types of tackiness develop. Traces of copper, for instance, cause rubber to liquefy, with formation of a sticky, transparent mass, which then gradually hardens, first on the surface and afterwards throughout, whereby it is transformed into a hard and brittle resin-like substance, easily soluble in acetone. The viscosity of a 1% benzene solution decreases from the normal figure of 30 to, say, 2. This type of tackiness is independent of light, as it develops quite readily in the dark. It is accompanied by an increase in weight of 7 to 13%. The change is regarded as an oxidation catalyzed by copper, but more knowledge about the course of this oxidation and the intermediate and ultimate products would be welcome. Hydrochloric acid, for instance when used as a coagulant, causes another characteristic form of tackiness, which is very dependent on the action of light, one side of a piece of crepe, for instance, becoming sticky and liquefying, while the other side, turned away from the light, shows no change. During this process also the rubber changes into transparent, yellow oily products, which gradually become hard and brittle; the increase in weight is 9 to 12%.
Influence on Final Product of Fast and Slow Vulcanizing Rubbers
Authors: Heywood M. M. 
Published: February 2011

Abstract
The object of this paper is to endeavor to carry beyond the laboratory stage the tests which have been hitherto published on the variability in vulcanization found in plantation rubber. It is easily appreciated that, when one is handling large quantities of rubber, it is impossible for economic reasons to buy from one estate or even one group of estates, but the whole of the available rubber has to be surveyed before purchases can be made. There are accepted classifications in London which, in many instances, are based on appearance rather than on intrinsic quality of the rubber. Cleanliness or eye value, although desirable, should not be the sole standard for quality of rubber. Each broker, agent, dealer or middle man between producer and user has his own type sample. Each user has his own conception of what he wants and generally has a type sample also. But variation in available rubbers does influence the final product, especially in regard to the manner in which a rubber vulcanizes. For the purpose of experiment, two wellknown rubber types have been chosen, and factory production runs covering a considerable tonnage have been studied.
Rubber Terminology
Authors: Dawson T. R. 
Published: February 2011

Abstract
A definite part of scientific activity consists in applying words to connote materials and ideas. Observed phenomena and the hypotheses derived from them are systematized and generalized by means of such terminology. Progress itself depends on words or equivalent symbols, for we have no other means of exchanging information. The universality of speech and writing tends to obscure the remarkable complexity of these processes, and the editor of Chemical Abstracts, in a recent admirable lecture, had occasion to deplore the numerous and serious deficiencies in chemical terminology. All that he said of chemical words in general applies, with perhaps greater cogency, to the terminology of the rubber industry. The science and technology of rubber are but in their infancy. They have been superadded to an industry developed for a century by practical men in the rough-and-tumble of the works. It is not surprising, therefore, that verbal exactitude has scarcely been considered. The infant rubber science has, however, shown' vigorous development in the last two or three decades, and there are signs that its attention is being awakened to the need for putting its verbal equipment in order. The issue is not only a scientific one. It is complicated by commercial considerations which cannot be ignored. Pithy trade names are undeniably better sellers than cumbrous systematic chemical names. The persistent use by the leather and leather footwear industries of the term “substitute soleing,” for what is, quite simply, rubber soleing, has undoubtedly prejudiced an excellent and serviceable product. The coining of some happy alternative, following the example of the replacement of “artificial silk” by “rayon,” would probably have effects measurable in terms of dividends. It must be realized, therefore, that any attempts to improve rubber terminology will be limited in some directions by trade considerations. That is not a reason why the industry's scientific literature, at least, should not be given all the clarity and precision that can be achieved. In the following discussion several directions are pointed out in which improvement would be welcome. The illustrative examples given are typical only and, unfortunately, are far from exhaustive.
Spontaneous Coagulation of Rubber Latex
Authors: Stamberger Paul 
Published: February 2011

Abstract
As early as 1913, Whitby advanced the view that spontaneous coagulation in rubber latex takes place before decomposition processes begin. Arguments against this view have since been advanced by several investigators, and the opinion generally held at present is that the coagulation of fresh latex is caused by formation of acid from the bacterial decomposition of the serum components. Recent investigations made on latex of Hevea brasiliensis have provided confirmation of the view held by Whitby. Experiments were conducted throughout on latex obtained immediately after collection from the trees, which had been tapped three or four hours previously. The formation of ions from decomposition of latex was followed by conductivity measurements. The conductivity of latex did not change until coagulation was complete. This occurred 6–11 hours after collection of the latex, varying from sample to sample. The resistance of the conductivity cell increased after gel formation, due to contact resistance on the electrodes.
Examination of Thin Rubber Films by Electron Diffraction
Authors: Tanaka Kenzo 
Published: February 2011

Abstract
It was reported in a preceding paper (Mem. Coll. Sei. Kyoto Imp. Univ. [A] 21, 85(1938)) that when a thin film of certain organic long-chain molecules coating a polished metal surface is heated, the regular arrangement of the molecules of the substance becomes haphazard at a temperature which is characteristic of the substance and differs from its melting point. This temperature was called the transition temperature of the molecular arrangement of the substance. In the present experiments the manner of the arrangement of the rubber molecules in a thin film deposited from benzene solution on a polished metal surface was examined in the same manner as before. To obtain rubber films of different thicknesses, a small piece of polished copper which served as the backing of the film was dipped for a moment in a benzene solution of rubber. The range of rubber concentration of the solution was from 2 to 0.005 per cent. By subsequent evaporation of benzene, a uniform coating of rubber was obtained, which was so thin as to show the interference fringe by light in most cases. The typical diffraction patterns obtained by an electron beam which impinged on the rubber film in a direction almost parallel to its surface are such as shown in Fig. 1. But these are rare cases, and generally the rubber films deposited as above stated gave rise at first to diffuse halos of amorphous structure. However, when these amorphous films were heated at about 70° C. for a while and cooled to room temperature, they gave rise to the same diffraction patterns illustrated in Fig. 1. The regular pattern showing the regular arrangement of the rubber molecules is well defined for very thin films, and becomes more diffuse with increasing thickness of the film, as in the case of other substances.
A Few Corrections of Statistical Theories of the High Elasticity of Rubber
Authors: Houwink R. 
Published: February 2011

Abstract
Theories have of late been developed to account for the high elasticity of certain substances, particularly rubber, over a particular range of elongation. These theories are based on the assumption that the molecules have taken a spherical form, which is the one statistically most probable. We wish to prove that, in order to avoid wrong conclusions, certain modifications in these theories are necessary, and we wish especially to make a stand against the following two assertions: (1) That rubber-like high elasticity is always associated with the presence of chain molecules. (2) That when rubber is elongated, no attractive forces are broken down and no valence angles are deformed until an elongation of about 350% is reached.