bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isoprene and Rubber. Part 28. The Fractionation and Cracking of Hydrorubber
Authors: Staudinger H. , Schaal W. 
Published: February 2011

Abstract
The Fractionation of Hydrorubber According to the investigations of Geiger, treatment of rubber with hydrogen in the presence of nickel at 270° brings about a reduction with simultaneous cracking of the macromolecules of the rubber. The hemi-colloidal hydrorubber thus formed ought not to consist of uniform long molecules, but of a mixture of homologous polymers; because in other similar cases mixtures of homologous polymers were obtained when macromolecular substances are decomposed, e. g., in the acetolytic decomposition of polyoxymethylenes and of cellulose. According to the views of Pummerer, on the other hand, if rubber consists of relatively small molecules, there would be no decomposition by cracking during its reduction, but only a saturation of individual primary valence chains with breaking up of the micellar structure, with formation of a hydrorubber whose molecules are uniformly long. Pummerer and Koch believed that they had obtained such a substance. To prove whether hydrorubber consists of a mixture of homologous polymers, it was split up into five fractions by fractional precipitation with alcohol from its ethereal solution, and the viscosities of the individual fractions were determined in 0.5 molar carbon tetrachloride solution (Table I).
An Investigation of the Effect of Gas Black on Rubber
Authors: Stamberger P. 
Published: February 2011

Abstract
1. It is shown that changes in the solubility of mixtures of rubber and gas black do not parallel changes in plasticity. 2. Rubber-gas black mixtures become insoluble only upon standing after milling, which makes it improbable that the insolubility of these mixtures depends upon a flocculation of the gas black in the mixture. 3. An adsorption of rubber from its solutions by gas black could not be established. 4. The heat of wetting of gas black with toluene and of a five per cent rubber solution in toluene were the same, as was the quantity of gas set free by the wetting. The dispersing action of rubber solutions does not depend upon a better wetting.
Mastication of Rubber. An Oxidation Process
Authors: Busse W. F. 
Published: February 2011

Abstract
The effects of milling and of exposure to light are similar in altering smoked sheet, pale crepe, and balata so that they affect a photographic plate in the dark. This effect is due to the formation of a volatile peroxide, probably hydrogen peroxide. No image is formed by sprayed latex, fine Para, anode rubber, or guayule after being milled or exposed to the light. The order of the intensity of the images formed by smoked sheets, pale crepe, and sprayed latex is the same as the order of their rate of change of plasticity on milling. Cold-milling is more effective than hot-milling, both in the formation of the peroxide and the breakdown of the rubber. Milling on a cold mill produces a luminous discharge from the blanket to the bank, but this disappears when the rolls are heated. Sprayed latex and fine Para contain some material which decomposes hydrogen peroxide. This accounts for the fact that peroxides could not be detected in these rubbers, either after exposure to light or after milling, even with the addition of hydrogen peroxide. Both copper and cobalt soaps decompose the peroxide in some instances, though under other conditions the cobalt soaps greatly increase the amount of peroxide in the rubber.
Crystallized Rubber
Authors: Pummerer R. , von Susich G. 
Published: February 2011

Abstract
In recent years various attempts have been made to crystallize natural rubber by some means other than by stretching. In the present paper the results of these experiments are described, together with some new observations, in order to settle the present status of the problem. The processes of crystallization are divided into three groups and discussed individually. 1. Spontaneous crystallization under conditions which vary but little from the normal conditions. 2. Crystallization from solution after purification. 3. Crystallization of a solution of purified rubber by cooling to a low temperature. It is a generally known fact that after storage for a year, plantation rubber becomes stiff, inelastic, and opaque. A rubber altered in this way is known as “frozen” rubber, because this change has been observed most frequently after storage in a cold place. The x-ray investigations of Katz and Bing have rendered it certain that during “freezing” there is crystallization of the rubber, because when subjected to x-rays frozen rubber shows crystalline interferences from which the same crystal lattice is calculated as that which is formed on stretching, except that the degree of orientation in frozen rubber differs from that of stretched rubber. This is seen in x-ray diagrams, where the nearly point interferences of the stretched samples lie on the same Debye-Scherrer circles as those of frozen rubber. There have been rather exhaustive investigations on those changes in frozen rubber which appear on warming, viz., during transformation of the crystalline to the amorphous state (the “fusion process”), and which are characterized by disappearance of the crystal interferences and by a discontinuous change in the heat content, specific gravity, hardness, and light absorption.
Isoprene and Rubber. Part 35. Soluble and Insoluble Rubber and the Fractionation of Rubber
Authors: Staudinger H. , Bondy H. F. 
Published: February 2011

Abstract
According to the views of earlier authors, the transformation of insoluble rubber to soluble rubber is reversible. Bary and Hauser speak of an equilibrium between the α and β forms which takes place rapidly. The reversion of insoluble rubber to soluble rubber is brought about by mastication, by chloroacetic acid and other acids, and finally also by standing in air. The fact was completely overlooked that the soluble rubber thus obtained has quite different properties from the original rubber. Its solutions have a low viscosity. Accordingly it is not a question of a reversion from insoluble to soluble rubber, but of a degradation. The conversion of insoluble to soluble rubber is a result of a cleavage of the molecules of insoluble rubber by reagents such as chloroacetic acid and oxygen, and finally during mastication. The 3-dimensional molecules of the insoluble rubber, which are composed of long fiber molecules of soluble rubber, are broken up in this degradation into short fragments which are also fiber molecules and therefore dissolve. The soluble rubber obtained by decomposition is of a hemi-colloidal character, and is not the original high molecular soluble rubber. A similar decomposition also takes place with further autoöxidation; the insoluble rubber passes rather quickly to degraded soluble rubber when it is heated in the strongly swollen state at 60° in the presence of air. Insoluble rubber is also rendered soluble by strong mastication. Here, too, there is a degradation by oxidation. Naturally it is also possible that a direct mechanical rupture of the chains takes place. A deeper insight into the process of mastication will be had only if rubber is masticated with the most careful exclusion of air.
Modifications of the Gutta-Percha Hydrocarbon
Authors: de Jong A. W. K. , Katz J. R. 
Published: February 2011

Abstract
The spongy product from gutta-percha hydrocarbon, which is obtained from a concentrated petroleum ether solution, consists of microcrystals of the α-modification. The difference in its solubility and that of the compressed product prepared from the spongy product is perhaps attributable to the presence of an impurity. By treatment of the fused hydrocarbon with benzene below 19° C. both the β-form and the amorphous form dissolve, and one of these forms is converted, or perhaps both of the forms are converted, into the α-form. It is possible that petroleum ether dissolves not only the amorphous form but also a part of the β-form. It does not, however, transform the β-form into the α-form. Compression in the cold of previously fused strips, as well as of strips elongated while cold, decreases the solubility of these strips in benzene below 19° C. Cold-drawing of threads, which have been prepared from fused products, has only a slight influence on the stability of the threads in benzene below 19° C.
Remarks on the Formation of Jellies in Rubber Solutions Containing Ultra-accelerators. Influence of the Solvent
Authors: Thiollet R. 
Published: February 2011

Abstract
Rubber solutions are used for coating fabrics, for cementing pieces of rubber, and for manufacturing certain objects like nipples. These various articles can be vulcanized in the cold with sulfur chloride, but it is becoming more and more popular to vulcanize them by the hot method, which necessitates the use of ultra-accelerators. Rubber solutions containing ultra-accelerators are often transformed, in some cases rapidly, into jellies which are absolutely useless. In connection with the formation of these jellies, we have made certain observations, which it is believed will be useful in the preparation of solutions containing these rapid accelerators. These observations deal with: (1) the influence of the accelerator, and (2) the influence of the solvent, on the rapidity of the formation of jellies. We studied first of all tetramethylthiouram mono- and disulfide, which are the accelerators most often used for vulcanizing in hot air. We have studied them alone and in combination with other accelerators, such as mercaptobenzothiazole, ethylidene-aniline, and anhydroformaldehyde-aniline. The solutions were made under the following conditions. A series of mixtures containing different accelerators was prepared from the same base mix by mixing on a roll mill. These mixtures were prepared with a constant distance between the rolls, and by passing the mixtures through the same number of times.
The Influence of Certain Accelerators on the Aging of Rubber
Authors: Martin G. , Thiollet R. 
Published: February 2011

Abstract
Among the accelerators which are at present on the market two are very much used, viz., diphenylguanidine as an accelerator of medium activity, and tetramethylthiouram disulfide as a rapid accelerator. Diphenylguanidine is used most of the time in proportions between 0.5 to 1 per cent, based on the rubber, and with about 3 per cent of sulfur. Tetramethylthiouram disulfide is used in proportions of between 0.2 and 0.5 per cent, based on the rubber, with about 1.8 per cent of sulfur. In this way “nervy” mixtures are obtained which have excellent physical properties; but it must be recognized that these two accelerators are, each in its class, the ones which impart to mixtures the poorest aging qualities. For example, the mixture: Pale crepe 100 Zinc oxide 5 Sulfur 3 Palm oil 1 Stearic acid 0.5 Diphenylguanidine 0.7 vulcanized 1 hour at 3 kilograms pressure, i. e., under conditions which lead to the best physical properties for the proportions used, was investigated.
The Effect of Pigments in Rubber
Authors: Boiry F. 
Published: February 2011

Abstract
1. Gas black, light calcined magnesia, litharge, hydrated lime, and, to a lesser degree, lamp black give mixtures which do not disintegrate in benzene hydrocarbons. These mixtures disaggregate only after prolonged immersion in an excess of solvent, and the less pigment they contain and the less disaggregated the rubber, as a result of the mechanical working, the longer is this time. The other pigments with rubber form mixtures which disaggregate very rapidly, and from which the rubber dissolves very rapidly. 2. This effect of pigments of the first group is a result of adsorption of the rubber by the pigment particles. 3. In the case of gas black and lamp black, this adsorption phenomenon depends chiefly upon the very great specific surface of these pigments. With magnesia and magnesium carbonate, with hydrated lime, and with litharge it depends chiefly upon a difference in electric potential between the particles of pigment and the rubber. 4. There is a relation between the influence of the pigments on the solubility of raw rubber and their reënforcing effect on rubber after vulcanization. Gas black, magnesium carbonate, and calcined magnesium are the most active in both these respects. The relation is clearly defined in the case of lamp black, less so with litharge, and much less so with zinc oxide and with hydrated lime. The differences in the behavior of these last pigments are apparently due to chemical reactions which take place during vulcanization. 5. Tests carried out to modify the properties of these pigments have not up to the present time given definite results.
Hysteresis and Reinforcement
Authors: Barron H. , Cotton F. H. 
Published: February 2011

Abstract
1. The relationships between work of extension, work of retraction, and hysteresis loss in vulcanized rubbers loaded with fillers have been examined. 2. The hysteresis loss in vulcanized rubber during a cycle of extension and retraction increases with amplitude to an extent comparable with the increase in work of extension. 3. If the work required to extend a vulcanized rubber to a given elongation be increased by compounding with fillers, the energy lost through hysteresis on slow retraction increases to a comparable extent. Hence reinforcement does not appreciably increase the ability of rubber to store energy. 4. With any rubber vulcanized to optimum tensile properties, hysteresis loss and work of retraction from any elongation are proportional to the work required to extend to that elongation. Therefore if the hysteresis loss during a given cycle be known, the work of retraction from the breaking point can be calculated. 5. The work of retraction from the ultimate breaking point of a vulcanized rubber increases slightly with reinforcement, and becomes greatest when reinforcement is at a maximum. This is thought to be a function of the rubber-filler interface. 6. No filler was found to lessen the work of retraction from the breaking point until the rubber was highly compounded. 7. It is suggested that the increased work required to rupture rubber that has been reinforced with fillers is mainly dissipated in overcoming consequent increased internal friction; a small quantity being converted to potential energy through strain of the filler-rubber interface.
A Short Note on the Tensile Testing of Rubber
Authors: Jones M. 
Published: February 2011

Abstract
The evaluation of rubber has centered largely around stress-strain phenomena, and the property of tensile strength is probably the one which has the most general application throughout the industry. Rubber exhibits stress-strain properties quite different from the majority of substances, and peculiar difficulties are introduced during the determination of tensile strength. Although tentative standards have recently been issued by the American Chemical Society, there is no evidence that these are being strictly adhered to, and there is still need for a more rigid standardization of tensile-testing methods. There are essentially two methods of tensile-testing: (1) Using dumb-bell test-pieces with a Bureau of Standards machine, or a Scott type of machine; and (2) Using ring test-pieces with a Schopper type of machine. It is generally supposed that higher tensile results are obtained by the former method. Recently, occasion has occurred to make a comparison between both types and to study the effect of certain factors upon each method.
An Investigation of the Causes of Spots Which Appeared Spontaneously on Rubberized Fabrics
Authors: Martin G. , Sisley J. 
Published: February 2011

Abstract
The opportunity was offered to examine a white rubberized fabric on which rosecolored spots had developed spontaneously. This fabric was to be used in the manufacture of white footwear, and was constructed of two plies of fabric, a white cloth and an unbleached cretonne cemented together by a rubber solution. On certain pieces of the plied fabric and on certain lots of the finished footwear, there gradually appeared patches of a rose color, which were especially prevalent on the unbleached fabric and on the white edge of the footwear. Since both unblemished cloth and cloth in various stages of spotting were available for examination, an investigation was made of the differences between the good and the bad fabrics, and of the causes of the rose-colored spots. An unbleached sample of cloth on which the rose-colored blemishes were intense was first examined. In this case extraction with boiling water gave a liquid with a slight acid reaction. Another portion of the same cloth, treated with 20 per cent acetic acid, yielded a dye, the reactions of which indicated that it belonged to the triphenylmethane group of dyes, since it resembled fuchsin and rosaniline. The presence of an aromatic amine in the aqueous extract could not be established.
Studies in the Vulcanization of Rubber. V. Dielectric Constant and Power Factor of Vulcanized Rubber
Authors: Kitchin Donald W. 
Published: February 2011

Abstract
1. Power factor and dielectric constant data have been given for vulcanized rubber samples tested over a wide range of composition, temperature, and frequency. 2. The real identity of the agents responsible for the peculiar dielectric behavior is not known. It seems probable that these agents are the rubber-sulfur molecules themselves. because the effects increase, under proper conditions, directly with per cent combined sulfur. 3. The effect of increasing sulfur content on the dielectric behavior is complex; it modifies not only these supposed agents themselves, but also the stiffness of their environment. Moreover, at a given sulfur content the agents are not identical but differ widely in relaxation time, and therefore in ability to respond; and with progressive addition of sulfur, the rubber does not increase continuously in stiffness, but, at a composition which depends on the temperature, passes rather abruptly from a soft to a hard state. 4. The temperature at which the transition from one state to the other occurs increases almost linearly with the sulfur content from −90° to +90° C. 5. In the soft state the behavior of vulcanized rubber with respect to compressibility, thermal expansion, dielectric constant, and power factor, and probably other properties, resembles that of a viscous liquid; in the hard state, that of a solid. 6. Rubber with less than 2 per cent combined sulfur shows low dielectric constant and power factor over the whole temperature and frequency range investigated; hard rubber, only at room temperature, where its rigidity restricts the response to the field. 7. Hard rubber, although not an electret, can hold an electric charge for 24 hours or more. The low dielectric constants of high-sulfur rubber samples found in measurements with a ballistic galvanometer were due to the disparity between its period of about one second and the long discharge periods of the samples. This led to the idea of dipole compensation shown to be incorrect by the high temperature results. 8. At temperatures sufficiently high to permit free response, the dielectric constant increases with sulfur content over the whole range. 9. If a dipole mechanism is involved, addition of sulfur to more than half the double bonds does not cause the dipole moment of the molecules to vanish owing to compensation. 10. The power factor of vulcanized rubber sheets decreases on stretch. 11. The data neither prove nor disprove a dipole mechanism. A critical experiment to settle this question is still wanting.
Heat-Resisting Inner Tube Stocks
Authors: Booth E. W. 
Published: February 2011

Abstract
A large number of laboratory tests were carried out which showed that to resist deterioration due to heat in an inner tube stock successfully, the following points should be observed: 1. Sulfur ratios should be very low. One per cent on the rubber content is sufficient for most stocks; some will require 1.2 per cent. This is true provided no sulfur-producing material is present. 2. When P33 Black or a similar soft black is used, 20 to 25 volumes are necessary. In the case of zinc oxide, blanc fixe, barytes, and the like, lower volumes will be necessary to obtain satisfactory resistance to tear. 3. The stocks should not be markedly overcured, especially if the cure is carried out at 50 pounds steam pressure (298° F.) or above. This is the opposite of former practice with stocks of higher sulfur ratio. 4. The accelerator chosen must be strong enough to combine practically all of the sulfur present, and yet should not be too scorchy to handle safely in the plant. 5. Tests showed that the use of 2 per cent of a good anti-oxidant was justified. One per cent gave good results, but especially when agings longer than 18 hours were carried out the stocks containing 2 per cent were markedly superior. 6. Zinc oxide, blanc fixe, barytes, or precipitated whiting can be successfully employed in stocks of this type. The modulus and tensile figures are lower than when P33 Black is used, but the losses in tensile strength due to air-bomb aging are comparable to P33 Black, and these fillers would permit the manufacture of colored tubes such as red, green, and yellow. 7. Heat-resisting inner tube stocks of this type compared to the ordinary tread, carcass, and tube stocks will necessarily be more scorchy, and care must be taken to cool the stocks properly in processing through the factory. The possibility of the migration of sulfur from the carcass stocks to the inner tube, or the migration of accelerator from the inner tube stock to the carcass stock must be taken into account. Today tire manufacturers are using as low as 2 per cent sulfur in the carcass stocks of bus and truck tires. These low sulfur ratios in the carcass stock tend to prevent the migration of sulfur. The usual Geer oven migration tests were carried out on stocks containing Ureka C as accelerator. The Geer oven was maintained at 93.3° C. (200° F.) for 14-day periods, and in no case did these tests show appreciable migration of sulfur or accelerator. Controls were run during the migration tests and alone.
Solubility of Organic Compounds in Rubber
Authors: Morris T. C. 
Published: February 2011

Abstract
While a few methods for solubility determination in rubber have been available, they are somewhat difficult and susceptible to large errors. A new method has been developed which has the advantage of being simple, rapid, and accurate, and applicable to all solids soluble in rubber. The apparatus developed can be used for any problem where microscopic observation at elevated temperature will yield information. The results thus far obtained are of use in explaining the peculiarities of certain organic compounds when used with rubber. It is hoped that sufficient data may be obtained to establish accurately the solubility properties of entire classes of compounds as well as mixtures of several components. In addition to molecular weight determination, the method may yield further results of theoretical interest.