bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zinc Oxide—A Product of Complex Physical and Chemical Properties
Authors: Depew Harlan A. 
Published: February 2011

Abstract
In the space available, it is obviously impossible to give more than an outline of the differences in pigment zinc oxide, of the significances of these differences, and of some of the methods by which these differences can be controlled. It is hoped, however, that the reader will conclude that zinc oxide is a product of complex physical and chemical properties, and that the manufacturer is able to manufacture zinc oxide of special properties to fit normal and unusual requirements.
A Torsional Hysteresis Test for Rubber
Authors: Mooney M. , Gerke R. H. 
Published: February 2011

Abstract
The mechanical hysteresis of rubber has been measured by almost every conceivable method, many of them simple but inexact. During recent years, however, the practical importance of hysteresis in rubber has been gaining recognition, and consequently a number of more elaborate and relatively exact methods and devices for measuring hysteresis have been developed. The present article describes a torsional hysteresis test. Although the apparatus required is quite simple, the test is accurate and may be regarded as a satisfactory test for many purposes.
Reactions between Compounding Ingredients during Vulcanization of Rubber
Authors: Bott E. C. B. 
Published: February 2011

Abstract
The calculations indicate that reactions (1), (3), and (5) can take place and proceed to virtual completion, whereas reactions (2) and (4) are not possible. They indicate also that the addition of extra sulfur to mixes containing litharge is necessary, and is in accordance with a custom long established empirically. It is evident that oxygen or nascent oxygen is not formed by any of these reactions; therefore no accelerated aging can take place by reactions between sulfur and litharge or zinc oxide. One peculiarity is that, although sulfur will react with litharge according to reaction (1), it appears that no oxygen is evolved by reaction (2), one possible reason being that the formation of lead sulfate takes place with a large decrease in free energy and is therefore readily formed. A possible explanation of the reaction between litharge and sulfur is that reaction (2), a possible first stage in reaction (1), is made to proceed to the right by the readiness with which lead sulfate can be formed. With respect to the reactions of zinc oxide, the assumption that zinc sulfide is formed by the action of hydrogen sulfide appears to be true.
Carbon Black in Rubber Compounding
Authors: Parkinson D. 
Published: February 2011

Abstract
The mechanism of filler reinforcement has not yet been fully explained, but there is general agreement that an important, probably the most important, factor is the enormous surface development between the rubber and filler due to the fine particle size of the filler. Explanations have been attempted to show how small particles can cause reinforcement, but a complete theory of the phenomenon which accounts for all the facts is still awaited. Particle size oj carbon blacks.—A knowledge of this property is important in an understanding of the mechanism of reinforcement by carbon black. Because of the difficulty of distinguishing between ultimate particles and compact aggregates, and because the particles themselves are too small to be resolved in an ordinary microscope, the usual microscopical methods of measurement are inapplicable. Ultramicroscopical methods have been used with some success, the results obtained by the method of Gehman and Morris being probably the most reliable. These authors quote an average particle size of 61µµ for a sample of a standard rubber gas black (Micronex). The figures given for P-33 black, Shawinigan acetylene black and Thermatomic black are 159µµ, 130µµ and 1120µµ, respectively.
Report of the Crude Rubber Committee. Presented at the Semi-Annual Meeting of the Division of Rubber Chemistry, September 12, 1940
Authors: Sackett G. A. , McColm E. M. , Nellen A. H. , Oldham E. W. , Parrish W. D. , Schatzel R. A. , Walton J. C. 
Published: February 2011

Abstract
The Crude Rubber Committee is always grateful for comments and suggestions regarding any of its published work or possible lines of investigation, and sincerely requests any member of the Division of Rubber Chemistry to send any ideas or opinions of the tests described here, or of tests in previous reports, to the Chairman of the Committee, so that they may be given consideration in further developments of the work in hand.
The Effect of Rapid Stirring on Latex and on Its Creaming
Authors: Van Dalfsen J. W. 
Published: February 2011

Abstract
1. The paper first discusses the determination of the mechanical stability of latex when stirred in a Hamilton-Beach mixer. Data are given on the stability of fresh latex, ammoniated latex, and concentrated latex. Particular attention is called to the increase in stability of ammoniated latex which takes place during storage, a phenomenon which is probably attributable to the formation of soap and accompanying increase in the charge of the latex particles. Soap added to latex increases considerably its stability and creaming capacity. 2. Fresh latex, stirred rapidly in a Hamilton-Beach mixer, undergoes microflocculation. The rapidly stirred latex coagulates entirely when it is allowed to stand quietly within a period of time which becomes shorter to the extent that stirring causes the mixture to approach more closely the point of actual coagulation in the mixer. This offers the possibility of coagulating fresh latex completely without the use of chemicals, but the method could be applied on a factory scale only with extreme difficulty. 3. When ammoniated latex is stirred rapidly for a time shorter than required for coagulation to become appreciable, microflocculation results. If, after having been stirred, such latex stands quietly, partial coagulation results. In this case the quantity of coagulum is greater, and the time for it to form is shorter, the more closely the mixing period approaches the coagulation point in the mixer.
Influence of the Temperature of Crystallization on the Melting of Crystalline Rubber
Authors: Bekkedahl Norman , Wood Lawrence A. 
Published: February 2011

Abstract
Data presented in this communication show an instance in which melting of a crystalline material is very much dependent on the temperature at which the crystals have been formed. It is well known that many substances in which crystallization is relatively slow can be crystallized at different temperatures in a range below the melting point, but no effect of the crystallization temperature on the temperature of melting seems to have been previously reported. The quantitative results for crystalline rubber, the material under investigation, are shown in Figure 1. The crystallization of unvulcanized rubber in the unstretched state has been found to occur at temperatures between about −40° C and 13° C. The time required for crystallization is about one year at 13° C, about ten days at 0° C, and a few hours at −20° C. Below −40° C the mobility is presumably insufficient for the formation of crystals. Crystallization and fusion are accompanied by changes in volume, heat capacity, light absorption, birefringence, x-ray diffraction, and mechanical properties such as hardness. The volume decreases about 2.5 per cent on crystallization, and the magnitude of the change is little influenced, if at all, by the temperature. Fusion, as measured by the volume increase, is found to be independent of the rate of heating, and to occur over a range of five or ten degrees.
Organic Analysis of Hevea Latex. IV. Amino Acids
Authors: Altman R. F. A. 
Published: February 2011

Abstract
The presence of amino acids in fresh latex was reported by Belgrave in 1925. On the basis of certain considerations, he considered it improbable that his experiments involved any profound changes in the original state of the nitrogen compounds. Accordingly the amino acids which he isolated must have been present in the free state in latex. It may be noted here that Belgrave's experiments did not completely exclude either chemical or enzymatic hydrolysis of proteins. Indeed, his amino acids were separated from a serum which was prepared by acidifying fresh latex with acetic acid (20 cc. of 10 per cent acid per liter of latex) and heating gently, with no precautions whatever for inactivating any proteolytic enzymes which may have been present. Aside from Belgrave's paper, there have been only two published references to the presence of amino acids in rubber or latex. Whereas Whitby, Dolid, and Yorston reported the isolation of valine from the acetone extract of crepe rubber, McGavack and Rumbold were able to isolate d-alanine from the serum of old ammoniated latex. There is no reason whatever for assuming from these observations that valine and alanine also occur free in latex. Indeed it would be impossible to give any guaranty that there was no hydrolytic degradation of proteins in the sample. In view of this situation it seemed highly desirable, as part of a systematic organic analysis of latex, to investigate more exactly the free amino acids which are present in latex. In addition to Belgrave's observation a preliminary analysis of fresh bottom latex which had been prepared for other purposes indicated that free amino acids actually do occur in latex. The object of the present paper is to identify the amino acids occurring in latex and, so far as is feasible, to determine the quantity also.
Estimation of Carbon Black in Neoprene Compounds
Authors: Scott J. R. , Willott W. H. 
Published: February 2011

Abstract
During a recent investigation it was necessary to determine the amount of carbon black in a sample of vulcanized Neoprene. The usual method adopted for vulcanized rubber, which consists in dissolving the rubber in nitric acid (British Standard Methods of Testing Vulcanized Rubber, B.S. 903–1940, p. 28), was tried without success, as the Neoprene did not dissolve. No methods for the analysis of Neoprene compounds appear to have been described in the literature; the following method of estimating carbon black, which has been found to work satisfactorily, may therefore prove of interest, especially as it can be used for certain other synthetic rubbers such as Buna. About 1.0 gram of the Neoprene sample is reduced to a fine crumb, such as will pass through a B.S. 10-mesh test sieve, by means of a rapidly rotating rasp. After extraction with acetone and chloroform, the extracted material is dried in a vacuum desiccator, transferred to a 400 cc. beaker, 20 cc. of nitrobenzene added, and the whole heated on a hot plate for a few minutes to allow the Neoprene to swell. 20 cc. of 25 per cent nitric acid (25 volumes of conc. nitric acid and 75 volumes of water) are then added, and the beaker is replaced on the hot plate. The Neoprene disintegrates and dissolves in the nitrobenzene in a few minutes. The beaker is then heated on a steam bath for about an hour, after which 100 cc. of xylene is added and the mixture filtered, while hot, through an alundum crucible or prepared Gooch crucible. The carbon is carefully washed with hot xylene till free from decomposed Neoprene, and finally with acetone. After drying at 150° C, the crucible is weighed, the carbon black then burnt off in a muffle furnace, and the crucible reweighed. The difference between these weights is the amount of carbon black present.
Introduction of the Bending-Strength Test as a Means of Determining the Freezing Point and Changes in Elastic Properties of Soft Rubber at High and Low Temperatures
Authors: Koch E. A. 
Published: February 2011

Abstract
A method for measuring the elastic properties of soft rubber at elevated temperatures and particularly at low temperatures, and for determining its freezing point, is described. This is the first time that a method for testing the flexibility of soft rubber has been used. The special advantages of this method are the small dimensions of the test-specimen and the consequent rapidity with which its temperature can be changed, the small weights with which the test-specimen is loaded, the low heat-capacity of the apparatus, and the ease with which the test-specimen can be made ready for testing. A change of samples can be made within five seconds. The time required for determining the freezing point and hardening point is about one-half hour, after which the apparatus is ready immediately for the next experiment. With a Dewar vessel containing 200–300 grams of solid carbon dioxide, about eight experiments can be carried out without refilling the vessel. Measurements can be reproduced to a fraction of one degree. The factors which, generally speaking, have an influence on the stability of rubber mixtures at low temperatures are discussed. Besides the method for determining freezing points of soft rubber mixtures, a definition of the stiffening point is proposed. Finally the method used for determining the modulus of elasticity of bending is described.
Dynamic Properties of Rubber. Dependence on Pigment Loading
Authors: Gehman S. D. , Woodford D. E. , Stambaugh R. B. 
Published: February 2011

Abstract
Dynamic properties are specific for different pigments. Curves show the dependence on pigment loading of the dynamic modulus, ratio of dynamic to static modulus, internal friction, dynamic resilience, and calculated relative heat generation at constant force and at constant amplitude. For the same volume loading, the dynamic modulus and internal friction rank in the order: Superspectra, channel black, zinc oxide, clay, blanc fixe, Thermatomic black, i.e., roughly in the order of particle size. The calculated dynamic resilience depends on the ratio of the modulus to the internal friction and increases in the order Superspectra, channel black, clay, Thermatomic black, blanc fixe, zinc oxide. The dynamic modulus shows an almost linear relation with the internal friction for different loadings of the same pigment. The dynamic modulus is independent of the frequency in the range 20–150 cycles per second. It depends on the amplitude, an effect which may be connected with the warming of the test-piece due to the vibration. The amplitude at resonance for the same driving force is approximately constant at all frequencies for a given rubber compound. The results show the wide range of dynamic properties obtainable with different pigments, and bring out the general principles involved in their use for dynamic purposes.
Some Dynamic Properties of Rubber
Authors: Harris C. O. 
Published: February 2011

Abstract
The following conclusions apply to rubber of the stock tested when bonded to steel: 1. For cylinders in compression and specimens in shear, the damping can be expressed in terms of a velocity coefficient. The damping decreases with increase of frequency; it increases with increase of static strain. 2. The dynamic modulus of elasticity is slightly larger than the static modulus and is not affected by change of frequency. It increases with increase of static strain for the cylinders and decreases for the shear specimens. 3. For cylinders in compression, both damping and modulus of elasticity are dependent upon the ratio of diameter to length.
Character of the Thermal Motion of Long Organic Chains, with Reference to the Elastic Properties of Rubber
Authors: Bresler S. E. , Frenkel J. I. 
Published: February 2011

Abstract
1. The theory of Mark and Kuhn, which assumes full freedom of rotation around the bonds of an organic chain, is criticized. Objections are raised as to the mechanism of elasticity of rubber proposed by these two investigators. 2. Based on the findings of Kistiakowsky, Pitzer and others, calculations are made of the elastic forces which hamper free rotation and thereby bring about a ribbonlike structure of the molecule. Calculations show the effect of these elastic forces on the thermal motion of the molecules and on their shape in solution. 3. It is shown that, if care is taken to calculate the modulus of elasticity correctly, the dynamic elasticity assumed by Mark and Kuhn is inadequate to explain the elastic behavior of rubber.
Sunlight and Accelerated Light Aging of Synthetic Rubbers
Authors: Morris Ross E. , James Robert R. , Werkenthin T. A. 
Published: February 2011

Abstract
Recently Werkenthin, Richardson, Thornley and Morris reported on the sunlight and accelerated light aging of various natural and synthetic rubber stocks, and proposed a method for standardizing the accelerated light aging test. The purpose of the present paper is to provide data on the correlation of sunlight aging with accelerated light aging for various synthetic rubber stocks loaded with mineral pigments. FORMULAS AND CURES The formulas and cures for the synthetic rubber stocks are given in Table I. These stocks have a loading corresponding to a good quality, 40 per cent wire insulation compound. Most of the prominent types of synthetic rubber manufactured in this country and one foreign synthetic rubber were included in this study. It was necessary to blend Vistanex Medium with natural rubber, inasmuch as this synthetic rubber cannot be vulcanized.
Nitroparaffins and Derivatives as Heat-Sensitizers for Rubber Latices
Authors: Campbell Arthur William 
Published: February 2011

Abstract
Recent research has made various nitroparaffins and their derivatives available in commercial quantities, and large-scale applications for the materials are rapidly being found. A considerable number of these compounds cause heat sensitization in rubber latices, a phenomenon that has been produced in the past by a number of materials, and is used extensively at present in the manufacture of foamed-rubber products. The use of nitroparaffins in this application is quite new, however, and has recently been the subject of extensive experimentation in this laboratory. In compounded latices it is not unusual to find three or more different materials, each with a definite purpose. In a study such as this, the use of completely compounded latices would unduly complicate the problem; so an effort was made to avoid these complications by running preliminary tests on the individual ingredients alone in a latex-nitroparaffin mix. It was found that gelling could not be produced by a nitroparaffin alone, even though the test mixtures were heated for considerable periods at 80–90° C. However, addition of a small proportion of zinc oxide to these mixes quickly induced gelling. It was also found that the oxides and hydroxides of the elements of Periods 2–6 of the Second Group of the Periodic Table gave results similar to those obtained with zinc oxide:
The Interaction between Rubber and Liquids. III. The Swelling of Vulcanized Rubber in Various Liquids
Authors: Gee G. 
Published: February 2011

Abstract
The entropy of swelling of vulcanized rubber is estimated, and assumed independent of the nature of the swelling liquid. The heat of swelling is related to the cohesive energy of the liquid, and a value of 66 calories per cc. deduced for the cohesive energy density of rubber. The swelling power of a liquid can be calculated approximately if its cohesive energy and molecular volume are known. Substantial agreement with theory is found in most cases, although it is necessary to consider aliphatic and aromatic liquids separately. The anomalously high swelling power of acids and alcohols arises from their association.
Equation of State of Some Synthetic Rubbers
Authors: Peterson L. E. , Anthony H. L. , Guth Eugene 
Published: February 2011

Abstract
The synthetic rubbers thus far developed bid fair to replace rubber permanently in hundreds of its varied uses. Though no one synthetic can, as yet, replace rubber in all of its applications, there are several synthetics available, each one of which excels rubber in one particular property. For example, some synthetics are oil- and gasoline-resistant, others resist the aging effects of heat, light, and oxygen, while still others surpass rubber in their resistance to flexing and abrasion.
Importance of Acidic Components in Compounding Ammonia-Preserved Latex with Zinc Oxide
Authors: Wren W. G. 
Published: February 2011

Abstract
In view of the experimental work described above, it appears that changes in viscosity of zinc oxide-compounded latex are due largely to the presence of ammonium salts of naturally occurring acids. These salts enable zinc to pass into solution, and to be absorbed by the latex globules, thus giving rise to the thickening commonly experienced. The amount of zinc passing into solution is directly proportional to the amount of acid present, and it is therefore suggested that determination of the acids by either of the methods described (viz., titration to pH 11 with caustic alkali, or from pH 7 to the end-point with hydrochloric acid), would form a sound basis for the classification of latices in regard to their behavior on compounding with zinc oxide. The investigations thus indicate that the variability of latex is due, in part at least, to the presence of acidic substances and may, therefore, be controlled by preventing the formation of the acids, or by their removal. Summary.—It is demonstrated that naturally occurring acidic substances control the solubility of zinc oxide in ammonia-preserved latex, and it is concluded that they are probably the controlling factor in determining the increase in viscosity which occurs in latex compounded with zinc oxide. In support of this view, it has been shown that the addition of various types of acid to ammonia-preserved latex markedly increases thickening after mixing with zinc oxide, and that the removal of naturally occurring acids reduces the thickening. It is suggested that titration of the acids in latex by the methods described forms a sound basis for the classification of latices in regard to their behavior on compounding with zinc oxide.
Effect of Temperature and Pressure on Oxygen Pressure Aging
Authors: Neal A. M. , Bimmerman H. G. , Vincent J. R. 
Published: February 2011

Abstract
An increase in the temperature of the oxygen pressure test from 70° to 80° C greatly increases the rate of aging of rubber vulcanizates. The temperature coefficients of aging rate for the six stocks tested vary between 1.63 and 3.48. The state of cure markedly affects the temperature coefficient of some stocks. It is obvious that no change in the specification from 70° to 80° C should be made without first determining the temperature coefficient of the stock involved. A decrease in the pressure of the oxygen pressure test decreases the rate of aging, but the rate is not proportional to pressure. The relative rates of aging between 0.5 and 300 pounds oxygen pressure for the stocks tested vary between 1.09 and 4.87 for the normal cures, and between 1.50 and 6.74 for the longer cures. The state of cure markedly affects the change in rate of aging with change in pressure. The data show that changes in the pressure of the oxygen pressure test must be accompanied by a revision of all aging specifications, which will involve an individual study of each stock and every cure of each stock, since no correlation between stocks seems to exist for the changes in rate of aging that occur with changes in pressure.