bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Viscosity of Latex and of Latex Mixtures
Authors: Bächle O. 
Published: February 2011

Abstract
For the rubber technologist, a change in the plasticity of rubber mixtures is one of the most important indications that fundamental changes are taking place within the mixture. For example, a decrease in plasticity would lead to the conclusion that incipient vulcanization had taken place, and an increase in plasticity would indicate degradation resulting from unfavorable conditions of storage, from the action of deleterious substances in the rubber, etc. Corresponding to these increases and decreases in plasticity in the case of dry rubber mixtures, increases or decreases in the viscosity of rubber solutions are found. These changes in viscosity and plasticity unquestionably conform to the facts which are now known about rubber and its behavior on degradation and on vulcanization. Further, latex, which is becoming of increasing importance, and mixtures prepared from it, undergo changes in viscosity on standing as well as during the processes of manufacture. There are many of these changes in the viscosity of latex, and accordingly it is much more difficult to ascertain them individually than it is in the case of solutions in organic solvents. It might be of importance to know more about the factors which influence the viscosity of latex. Then again in studying the viscosity of latex a great number of phenomena and problems are encountered which require explanation, so that a report of all the observations made during our investigation may be found of general interest.
The Viscosity of Raw Rubber
Authors: Smallwood Hugh M. 
Published: February 2011

Abstract
1. Eyring's equation for the viscosity of a non-Newtonian fluid describes Mooney's data satisfactorily for all except the lowest shearing stress. 2. From the standpoint of the present theory, the behavior at low shearing stresses may most readily be explained by any of the following assumptions: (1) the moving particle is larger at low than at high shearing stresses; (2) the rubber as a whole is less oriented by the lower shearing stress; (3) the distance “jumped” at the low shearing stress may be less than that at high stresses. 3. According to the present interpretation, the moving particle (corresponding to the molecule of a simple liquid) is larger than the rubber molecule. It does not seem profitable to interpret this finding as evidence for the existence of a rubber micelle. 4. Both the activation energy of viscous flow for this particular sample of rubber, and the factor determined by the spatial requirements which must be fulfilled by the moving particle, are much larger than the analogous quantities for low molecular hydrocarbons.
The Effects of Elastic Stretch on the Infrared Spectrum of Rubber
Authors: Williams Dudley , Taschek Richard 
Published: February 2011

Abstract
Previous studies of the infrared absorption of rubber have been made by Stair and Coblentz and by Williams. Stair and Coblentz observed a small band at 6µ and an intense band near 12µ, in addition to the usual hydrocarbon bands at 3.4µ, 7.0µ, and 7.3µ. An interesting study of the effects of aging (oxidation) was carried out by these authors, and it was found that marked increases in absorption occurred at 2.8µ, at 6.0µ, and in the region between 7µ and 12µ. Williams obtained transmission data for several types of latex rubber and compared the spectra of these materials with those of related hydrocarbons, such as isoprene and styrene. It was found that the small absorption band observed at 6µ by Stair and Coblentz was actually a complex band having several maxima. The results obtained were in fair agreement with the Raman data obtained by Gehman and Osterhof in their studies of solutions of rubber compounds, although the Raman studies revealed the presence of a number of minor frequencies which did not appear in the infrared work. It has been suggested by a number of writers that the mechanism of elastic stretch is intimately connected with the structure of the rubber molecule, and a theory has been developed by Mack which accounts for stretch and retraction in terms of a rotation about single bonds in the isoprene polymer. That profound changes take place in the structure of rubber when stretched has been revealed by x-ray studies, which show that the diffraction patterns of unstretched rubber consist of the diffuse bands characteristic of liquids, while the patterns of stretched rubber are well defined as in the case of crystalline substances. Other evidences of radical changes in structure accompanying stretch are the variations in optical properties which occur. It was suggested that further infrared studies might be of value in obtaining additional information concerning the mechanism of stretch. Hence it was decided to obtain transmission curves for rubber under different conditions of stretch in an effort to detect any changes that might occur.
High-Speed Vulcanization of Rubber
Authors: Kemp A. R. , Ingmanson J. H. 
Published: February 2011

Abstract
PRIOR to about 1906 when organic accelerators were first employed in the tire industry, vulcanization practice for soft rubber generally involved the use of larger amounts of sulfur than is now customary. Acceleration of vulcanization was obtained by the use of liberal amounts of one or more of the oxides of zinc, calcium, magnesium, or lead. As the new and faster organic accelerators have been employed, the amount of sulfur used has been gradually decreased until it now ranges from about 0.5 to 5 per cent of the rubber; the general tendency is towards the use of the smaller quantity. In the rubber-insulated-wire industry in this country, it is becoming general practice to employ the Western Electric Company's continuous vulcanizing process (1) whereby highly accelerated soft-rubber insulating compositions are completely vulcanized at 198° C. in a few seconds on the wire as it passes continuously at high speed from the insulating machine through a long pipe filled with steam under about 200 pounds per square inch (14.1 kg. per sq. cm.) pressure. This process is rapidly displacing the older one of coiling the insulated wires on drums or in pans filled with soapstone powder and vulcanizing in large autoclaves for periods of 1 to 5 hours under 20 to 40 pounds steam pressure (126° to 142° C.). The continuous process eliminates the objectionable soapstone dust and produces more uniformly vulcanized wire which is free from crossover defects and flattening of the insulation. The process also provides attractive economies in manufacture.
A Vulcanization of Rubber Latex by Potassium Ferricyanide
Authors: Spence D. , Ferry J. D. 
Published: February 2011

Abstract
(1) Vulcanization of rubber is produced by heating latex, from which the diffusible serum components have been removed, with potassium ferricyanide in the absence of air. (2) In the course of the treatment, the ferricyanide is reduced to ferrocyanide. (3) A similar effect may be produced by certain other metallic oxidizing agents in the absence of air.
Rubber in Compression
Authors: Morrison J. 
Published: February 2011

Abstract
Rubber is hardly ever used under simple stresses or strains. A tire tread or conveyor cover is subjected to compression, shear, tension, cutting, and tearing in such a variable and complicated manner that an exact analysis of working conditions is obviously impracticable. Therefore physical tests on samples of rubber will probably never assume the same degree of importance from the point of view of design as in the case of metals, and their primary function will remain that of providing standards for relative comparison of different qualities. Moreover, the comparative value of physical tests is severely handicapped by the variable nature of rubber and by its great deformability, which prevent its being subjected to completely and accurately known stress or strain. Reece (Trans. Inst. Rubber Ind., 11, 312 (1935)) has pointed out the non-uniform distribution of stress which occurs in tensile testing with dumb-bell test-pieces owing to the necessity for enlarged ends and having to grip the ends and apply the tensile loading initially as a shear through the surface of the test-piece. In compression testing, the difficulties of securing uniform behavior are much more pronounced. The obvious way to compress rubber is to use a cylindrical test-piece which must be short enough in relation to its diameter to avoid lateral buckling and compress it endwise between parallel plates. Although this does not involve actually gripping the test-piece, the frictional resistance to lateral sliding of the end surfaces on the plates is so great that the rubber deforms to a barrel shape, and the stresses and strains vary in an unknown manner and to such an extent that test-pieces of different sizes behave quite differently.
Extrusion Qualities of Rubber. Effect of Temperature and Mill Roll Opening
Authors: Nellen Arthur H. 
Published: February 2011

Abstract
EVERYDAY milling practice shows that rubber becomes softer when milled on a cold mill than when milled for the same length of time on a hot mill, and also that a tight mill will produce softer rubber than an open mill, using the same number of passes. Although this may seem obvious to one who is experienced in rubber milling, the published work on variations in the softness of rubber resulting from differences in roll temperatures and mill roll setting is meager; additional data on this subject would not be unwelcome in rubber literature. Also, a series of tests to determine the effects of these factors on the working qualities of rubber provides a satisfactory means for describing a method for operating a tubing machine plastometer which has proved to be of considerable value in this laboratory.
A New Revised Rebound Resiliometer
Authors: Bashore H. H. 
Published: February 2011

Abstract
The following points seem to cover the field of utility for this instrument: for measuring resilience, a property differing from hardness, modulus, elongation, plasticity, etc. For greater speed and accuracy in duplicating rubber compounds. For simplified method for control of factory mixing. For measuring plasticity, since rubber becomes less resilient and more plastic on prolonged mixing. For controlling and comparing the quality of finished products. For measuring the resilience and softness of sponge rubber.
X-Ray Study of Rubber Structure
Authors: Acken Marshall F. , Singer William E. , Davey Wheeler P. 
Published: February 2011

Abstract
IT IS SHOWN by x-ray diffraction methods that a time interval is required to build up a fiber structure in stretched rubber. Four rather obvious types of explanation for this effect are pointed out, and serious objections to three of these are mentioned. The most probable explanation seems to be that time is required either to squeeze out unfavorably oriented molecules to the interfaces of fibers made up of favorably oriented molecules; or to pull out, in the direction of fiber-orientation, tangled portions of molecules. Such a picture would cause the easily stretched, favorably oriented molecules to assume the role usually played by the more solid phase of a gel, and would cause the less favorably oriented molecules (or portions of molecules) to play the part ordinarily played by the liquid phase of a gel.
Reactions during Vulcanization. I—Influence of Zinc and Lead on Rate of Cure of Stocks Accelerated with Tetra-methylthiuram Monosulfide
Authors: Jones H. C. , Depew Harlan A. 
Published: February 2011

Abstract
The acceleration of the vulcanization of rubber by thiurams at low temperatures is reduced by the addition of free lead oxide and water-soluble lead salts, but not by insoluble lead salts. The retardation is due to the inactivation of part of the accelerator by the lead through the formation of an insoluble compound, and the amount inactivated is related to the amount of lead present. An equilibrium apparently exists between the amounts of zinc oxide and lead oxide and the accelerator, which is ordinarily on the side of a very large amount of the lead compound. When an excess of the thiuram is present, a white product can be obtained even when litharge is present in the stock, which indicates further that the lead combines with the accelerator to form an insoluble material inactive at low temperatures. The increasing activity of the lead compound with increasing temperatures can be explained by increasing solubility in rubber. The insolubility of the lead compound is further indicated by the fact that if the thiuram is added to a stock containing soluble lead, it is less effective than if it had been added after the lead so that the particles of accelerator would have had time to disperse in the rubber, rather than be coated by the insoluble lead compound.
Oxidation Studies of Rubber, Gutta-Percha, and Balata Hydrocarbons
Authors: Kemp A. R. , Bishop W. S. , Lasselle P. A. 
Published: February 2011

Abstract
The oxidation mechanism of rubber and gutta-percha hydrocarbons has been studied. Rubber hydrocarbon in sheet form oxidizes more slowly and less completely than precipitated gutta-percha, which is believed to be due to the smaller surface exposure of the former material. Gutta-percha hydrocarbon in finely divided form oxidizes to a fairly definite degree in oxygen at room temperature, corresponding to a weight increase of about 38 per cent. The length of the autocatalytic induction periods for rubber and gutta-percha varies over a wide range and is shortened by heating the hydrocarbon in high vacuum before oxidation and by exposure to light. The rate of oxidation of gutta-percha in air, as compared with oxygen, is reduced in proportion to the oxygen concentration, and the induction period is correspondingly increased. Carbon dioxide, water, formic acid, and formaldehyde are identified in the volatile oxidation products, and their relative amounts determined. Six to eight per cent of the hydrocarbons are converted to volatile oxidation products. The percentage unsaturation of both rubber and gutta-percha hydrocarbons is reduced in proportion to oxygen absorbed. The ratio of hydrogen to carbon decreases as a result of oxidation. The solid oxidized products are of such a nature that they cannot be resolved into crystalline materials. They are amorphous acid substances, free from aldehyde and ketone groups. They contain a small amount of peroxides; and the acidity, saponification value, and other properties indicate that most of the oxygen is combined in the form of hydroxyl, carboxyl, and lactonic groups. The mechanism of oxidation of rubber and gutta-percha appears to be the same, and the possibility of a chain mechanism to explain the facts is discussed.
New Condensation Products of Rubber Hydrocarbons by the Aid of Benzyl Chloride
Authors: Kirchhof F. 
Published: February 2011

Abstract
The application of the long-known Friedel-Crafts reaction to rubber hydrocarbons led to a new type of condensation products which may be called provisionally aral cyclorubbers (“benzylidene rubbers”), since their benzylidene groups are probably condensed with the polyprene skeleton to cyclic systems. It would not have been foreseen without further work that rubber would form this type of condensation product with aral halides in the presence of aluminum chloride, since on the one hand benzyl chloride is known to form, by the action of aluminum chloride in the Friedel-Crafts reaction, an amorphous, apparently high molecular hydrocarbon of the empirical composition (C7H6)x, and on the other hand rubber in solution is transformed by the metal chlorides, especially aluminum chloride, into amorphous polycyclorubbers. Under definite conditions of condensation with aluminum chloride aral groups are combined with the skeleton of the rubber hydrocarbon with the formation of white to yellowish amorphous bodies which contain, in addition to a small proportion of organically combined chlorine, only carbon and hydrogen, and are therefore to be regarded as hydrocarbons. In their physical and chemical properties these substances resemble the already known amorphous substance of the empirical formula (C7H6)x, which doubtless is polybenzylidene, probably hexabenzylidene.
The Nature of Vulcanization. Part IV (Continued)
Authors: Stevens H. P. , Stevens W. H. 
Published: February 2011

Abstract
In a previous communication the authors have discussed the limiting figure for combined sulfur in vulcanized rubber, and shown that under suitable circumstances the coefficient of vulcanization can exceed the figure of 47, which is that required by the formula C5H3S. It was thought that the combined sulfur in excess of this amount resulted from the substitution of sulfur for hydrogen. (Further information on this point will be found in the second part of this paper.) In the course of these experiments use was made of the ether-hydrochloric acid extraction method for the removal of mineral sulfides in soft vulcanized rubber. It was thought that this extraction method might not be suitable for use with vulcanites, since the amount of swelling produced by the ether was relatively inappreciable, and consequently the metallic sulfides were not necessarily decomposed. It was also thought that the acid mixture might react with a part of the rubber sulfide and result in a lower coefficient, which would depend on the time of extraction. It is known that vulcanite can be decomposed by the action of alcoholic potash, and the combined sulfur has been reduced in some cases to 26 per cent. It is reasonable to suppose that decomposition takes place in the presence of concentrated hydrochloric acid. In order to determine the extent to which the sulfide is decomposed by the action of the acid a series of extractions was made.
Micellar and Molecular Solutions of Rubber
Authors: Bary Paul 
Published: February 2011

Abstract
The chief interest in studying the degradation of rubber lies in the fact that it makes possible an investigation of the manner in which substances first swell in a liquid before they disperse. There are two opinions current about the state of rubber in its solutions; one, for several years the most popular, is that rubber consists of micelles in the liquid; the other is that rubber is a molecular dispersion with the molecules in the form of chains which may be very long. This latter hypothesis has been taken up comparatively recently by Staudinger, and is supported by a large number of experiments. In the investigation being carried out by the author and E. Fleurent on the degradation of rubber, of which the preliminary results have already been published, the object has been first of all to determine the law according to which the degradation progresses with time under different conditions of solvent, concentration and temperature. When one operates with dilute solutions (0.4 to 2%), the law of degradation is easily proved to be proportional to the time, but these solutions have no appreciable rigidity until they are homogeneous, and all the viscosity measurements of the solutions can be made with a single viscosimeter, without waiting for too long a period of flow.
Isoprene and Rubber. Part 29. High Molecular Hydrorubbers
Authors: Staudinger H. , Feisst W. 
Published: February 2011

Abstract
The molecular concept in organic chemistry is based upon the fact that the molecules, whose existence is proved by vapor density determinations, enter into chemical reactions as the smallest particles. If now it is assumed that organic molecular colloids like rubber are dissolved in dilute solution in molecular form then it must be proved that in the chemical transposition of macromolecules as well no change in the size of the macromolecules occurs. In the case of hemicolloids, therefore for molecular colloids with an average molecular weight of 1000 to 10,000, this has been proved by the reduction of polyindenes, especially of polysterenes, to hydroproducts with the same average molecular weight, and also by the fact that cyclorubbers do not change their molecular weight upon autoöxidation. The molecular weights of hemi-colloidal hydrocarbons are therefore invariable. This is much more difficult to prove in the case of rubber, although there are many more ways in which unsaturated rubber can be transposed than the stable polysterenes, polyindenes, and poly cyclorubbers. In most of the reactions with rubber, as in its action with nitrosobenzene, oxidizing agents, hydrogen halides, and halogens, an extensive decomposition takes place as a result of the instability of the molecule, which is referred to in another work. Therefore derivatives of rubber are not formed, but derivatives of hemi-colloidal decomposition products. The catalytic reduction of rubber in the cold appears to be the most suitable process of making it react without changing its molecular size in order to prove that in a chemical transposition its molecular weight remains the same.
Mastication. A Preliminary Study
Authors: Cotton F. H. 
Published: February 2011

Abstract
1. The oxygen present during mastication of raw rubber is responsible for the increase in plasticity which normally occurs. 2. Rubber does not soften appreciably when masticated in nitrogen. There are indications that rubber free from adsorbed oxygen would undergo no change on mechanical working in pure nitrogen. 3. The value of the so-called constant n in the plasticity equation K=XYn changes from one sample of masticated rubber to another. It varies from 0.07 in the case of a tough raw rubber full of nerve, to 0.28 in the case of the same rubber masticated in air or oxygen until thoroughly “killed.” 4. Small quantities of ozone are formed by the static electrical charges produced on rubber during mastication. 5. Rubber does not masticate more rapidly in ozonized air or ozonized oxygen than in air and oxygen, respectively. 6. The volatile products of the action of ozone on. vulcanized rubber have a retarding action on the mastication of rubber, particularly during the initial stages. 7. Dry rubber gains steadily in weight during mastication in air. The rate of absorption of oxygen decreases slightly until the rubber has gained 0.22 per cent in weight. Thereafter, the rubber becomes tacky and the rate of absorption increases. 8. During mastication of rubber in air or oxygen, volatile products are evolved having an acrid odor resembling that of the aldehydic products of the reaction between ozone and vulcanized rubber. 9. A suggested mechanism of mastication has been put forward to explain the above findings.
Impure Iron Oxide as a Rubber Pigment. I. Effect of Ferric Sulfate on Cure and Aging of Rubber
Authors: Ayers Joseph W. 
Published: February 2011

Abstract
1. Traces of ferric sulfate in oxide of iron will accelerate aging of rubber. 2. Traces of ferric sulfate in oxide of iron will cut down the rate of cure of rubber. 3. The Bierer-Davis bomb aging tests and the Geer oven tests lead to the same conclusions, although the stocks perform differently in each case. 4. By changing the ferric sulfate to ferrous carbonate with sodium carbonate in solution and washing out the residual sodium sulfate, the ferric sulfate is neutralized to an inactive salt. 5. Iron oxide aggregated by ferric sulfate will not break down on milling in rubber. 6. Increased aggregation reduces the specific surface and the coloring or tinting value of the pigment.