bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fractionation of Rubber
Authors: Bloomfield George F. , Farmer Ernest Harold 
Published: February 2011

Abstract
Latex rubber which has been purified to the point at which it contains an insignificant amount of nitrogen can be separated by fractional dissolution in a mixture of petroleum and acetone into a series of hydrocarbon fractions of decreasing solubility and increasing molecular magnitude. All these fractions except the highest are soluble in petroleum and in benzene. Crepe rubber, on the other hand, appears invariably to contain a small, most-soluble fraction of oxygenated rubber, and a small similar quite insoluble fraction of material of high molecular weight. Between these extremes the rubber can be divided into fractions of increasing molecular weight, although, up to the present, about 70 per cent of the total rubber has appeared in a single fraction. It may be possible later, by judicious choice of another pair of solvents, to resolve this major fraction into a series of subfractions. Kemp and Peters refer to the effect of polar nonsolvents in reducing the viscosity of rubber solutions and also in assisting to bring gel rubber into solution, phenomena to which the polar molecules conceivably contribute by countering the forces of association between the rubber molecules. The present series of fractionations was conducted throughout in the presence of a polar nonsolvent (acetone), and hence may be considered to approach towards a separation of true rubber molecules as distinct from molecular aggregates. It is found, however, that, whereas the more soluble fractions of acetone-extracted crepe rubber contain small proportions of nitrogen, the least soluble fractions contain substantial proportions. Any effect which the nitrogenous material may have in assisting to link together hydrocarbon molecules to which it is attached, i. e., in contributing to the high-molecular condition of a portion of natural rubber, remains at present uncertain in character. The fractions of rubber, and especially the higher ones, show a strong tendency to become insoluble when they have once been freed from the last traces of solvent. It seems doubtful whether the decreased solubility is due to oxygen as it would require to be effective at exceedingly low concentrations.
Rubber Solvents Which Are Economically Self-Sufficing
Authors: Paselli Piero 
Published: February 2011

Abstract
Mixtures of dichloroethylene and trichloroethylene are not only suitable for preparing rubber solutions, but are superior in solvent power to gasoline now used in practice. If small percentages of alcohol are used in conjunction with these solvents, rubber solutions of lower viscosities are obtained, and in general these mixed solvents have high solvent power and are of value industrially. Mixtures of dichloroethylene and trichloroethylene are also of utility in preparing solutions of artificial rubber, such as Buna. These solutions are to be the subject of a special study. In the recovery of such mixtures of solvents, carried out with saturated steam, the alcohol is lost, evidently because it is miscible with the condensed water, but the other two components are recovered without any decomposition and under the same conditions as gasoline and benzene. In view of all this, chlorinated solvents, which are economically selfsufficing, ought soon to be used, if not in all cases, at least to a great extent, in place of gasoline and benzene, which are much more necessary for other uses than for the impregnation of fabrics. The use of chlorinated solvents has, in addition to this, notable technical advantages, as well as safety. Accordingly it seems likely that chlorinated solvents and their mixtures are destined to assume in the near future a dominant position in the rubber industry in general, and in the Italian rubber industry in particular.
Reclaimed Rubber. Application of the T-50 Test
Authors: Palmer Henry F. , Crossley Robert H. 
Published: February 2011

Abstract
1. If reclaimed rubber is introduced into a rubber compound, the T-50 values for the early part of the cure are lowered. This lowering is due in part to the faster rate of cure of the compound containing reclaim, and probably in part to the influence of the combined sulfur present in the reclaim itself. This lowering of T-50 value manifests itself chiefly during the early cures, diminishes as the cure progresses, and finally disappears. 2. The T-50 test should not be used to compare the relative states of cure of compounds containing different or unknown amounts of reclaimed rubber. 3. The T-50 test can be used to determine the effect of reclaimed rubber on the rate of cure of a compound by comparing the slopes and positions of the T-50 curves at various curing times; conclusions reached in this way can be substantiated by free sulfur data. The T-50 test appears to be somewhat more sensitive for this purpose than tensile and modulus tests. 4. T-50 tests on the reclaim-sulfur mix are more uniform than tensile strength tests, and indicate that variations in tensile strength are caused by factors other than variations in chemical state of cure. The T-50 test will, to a limited extent, distinguish differences in the rates of cure of reclaims in this mix. In general, however, the reclaim-sulfur mix is not so informative in the evaluation of reclaimed rubber as a test of the reclaim in a compound typical of the one in which it will be used. 5. As a means of interpreting the rate of cure of rubber and reclaimed rubber compounds, the T-50 test possesses advantages of speed, simplicity, and accuracy, and is a valuable addition to the standard testing methods now in use.
Vistanex Polybutene—Rubber Blends
Authors: Longman S. 
Published: February 2011

Abstract
From the foregoing data on blends of Vistanex Polybutene and rubber, it is evident that these two materials complement one another. Each has properties which the other lacks, and blends of the two can be made to emphasize the more desirable properties of either one. Extreme flexibility in compounding these blends is possible, since they are perfectly compatible in milled compounds. Therefore, great latitude is given in compounding of these blends to secure any range or degree of properties possible with either of the components. Vistanex Polybutenes should not be considered as synthetic rubber, because they will not vulcanize, and they lack certain characteristics of vulcanized natural rubber. More properly Vistanex Polybutenes should be considered as modifying agents for partial substitution of natural rubber. In many cases, this substitution of a part of the natural rubber in a compound by Vistanex Polybutene confers definite advantages and improves qualities of such compounds for special uses. Therefore, Polybutenes, even in normal times, have a very definite field of usefulness and, in the event that imports of natural rubber become restricted, the availability of the Vistanex Polybutenes in quantity will be of increasing importance to the rubber industry. Since the raw materials for the manufacture of Vistanex Polybutene are petroleum products, the availability of raw materials is a source of no difficulty in this country. Likewise, the manufacturing equipment is not excessively expensive, and, with expanded production, lowered prices may confidently be expected.
Electrical Tests and the Problem of Cure
Authors: Waring J. R. S. 
Published: February 2011

Abstract
Considerable changes in electrical conductivity, as well as in other electrical properties, of rubber mixes occur during the process of vulcanization. The practical man will want to know the answer to such questions as: Are the tests reproducible? To what type of use could the test be put? The answer to the first question is that electrical tests are readily reproducible. There are, however, two main sources of trouble, first the electrode system and, secondly, the lack of uniformity in material submitted for test, due to different previous history. The first difficulty can be overcome either by moulding in the electrodes, as in the oven experiments described, or by using a test in which no electrodes are required, as in the eddy current test. The second difficulty involves checking the processing previous to vulcanization. The following uses are suggested as an answer to the second question: checking processing by following cure on samples supposed to be the same; checking uniformity in rubber articles by tests on the finished products, e.g., a tire tread, without destroying the articles concerned, and checking cure by making tests on small samples in the laboratory. These examples are given by way of illustration. No doubt others could be suggested. Finally, it must be said that, particularly on the processing side, further work needs to be done, and the results will be communicated at a later date.
Determination of Free Sulfur in Vulcanized Rubber
Authors: Mackay J. G. , Avons C. H. J. 
Published: February 2011

Abstract
In a rubber laboratory controlling uniformity of factory production by physical and chemical testing, free sulfur is perhaps the most important determination. In this investigation recently described methods for determining free sulfur have been compared. A previous examination by one of the present authors of various methods of estimating free sulfur led to the adoption of a procedure comprising oxidation of the dried acetone extract by a mixture of nitric acid, perchloric acid and bromine, followed by evaporation with sodium chloride and hydrochloric acid before precipitation of sulfate in the usual manner with barium chloride. In the Avon laboratories considerable use has also been made of the method recommended by the Rubber Division of the American Chemical Society, in which bromine alone is used to oxidize the acetone extract, and the sulfate so produced is estimated gravimetrically as the barium salt. Both methods are accurate, but they are not sufficiently quick for effective factory control. Meantime there had been published several new methods of determining free sulfur which were claimed to be quicker than the older procedures. With the aim, therefore, of finding a rapid method more suited to the requirements of a control laboratory, the following methods have been compared. Methods 1 and 2 below were included as controls. As test-samples, 22 different general rubber products selected from factory production were used. Each product contained at least one sulfur-bearing ingredient in addition to the sulfur added to effect vulcanization.
Phase Transitions in Rubber and Their Connection with the Stress-Strain Curve
Authors: Alfrey T. , Mark H. 
Published: February 2011

Abstract
This paper reviews recent experimental work on phase transitions in rubber—particularly the change from the amorphous to the crystalline form. Several possible explanations are considered to account for the vagueness of the melting point of rubber. Molecular inhomogeneity does not completely explain the phenomenon, and a more satisfactory approach involves a size-distribution of effective kinetic units. It is suggested that the reason for such a variation in size of the kinetic units lies in the mutual interference of growing crystallites. Crystallization of rubber by stretching is discussed, and it is shown that the crystallization process, which takes place mainly in the middle part of the extension, accounts in a reasonable way for the S-shaped nature of the stress-strain curve.
Fractionation of Rubber
Authors: Bloomfield G. F. , Farmer E. H. 
Published: February 2011

Abstract
H. P. Stevens wrote that he had read with interest the above paper and desired to contribute the following observations. The authors refrained from drawing conclusions from the varying nature and proportions of the fractions in the three typical rubbers of which they gave the distribution in three tables. The impression was obtained that those differences resulted from differences in the nature of the three types, either partly chemical or physical (molecular weight variations), or both. It was suggested by the writer that the main differences were of a different nature, and resulted from differences in the coarser structure of the specimens. It would be noted that “crepe rubber” (Table I) was rubber prepared by milling wet or semidry coagulum. “Latex rubber” (Table II) was acetone-coagulated after purification, and “dried-fresh-latex film” (Table III) was neither milled nor purified nor coagulated. The three specimens therefore corresponded to three dissimilar types of raw rubber. They would consequently possess different types of macrostructure. Rubber, however prepared, was not merely a mass of hydrocarbon with nitrogen and other accessory substances homogeneously distributed therein. The distribution was of a structural character.
Analytical Methods in Rubber Chemistry, Part I. General Analytical Considerations
Authors: Farmer E. H. 
Published: February 2011

Abstract
One of the consequences of the high-molecular character of rubber is the smallness of the effect on ultimate quantitative analysis of the presence of one or even several heteroatoms or groups in the long hydrocarbon chains. With rubber molecules possessing an average chain-length of about 4,500 isoprene units, the association of, say, ten nitrogen atoms wtih each chain would provide a nitrogen content of only about 0.0007 per cent, and the incorporation of about 0.005 per cent of ethereal oxygen in pure rubber hydrocarbon would be theoretically capable of providing sufficient linking material for an infinite degree of hetero-polymerization, or, if the oxygen were applied instead to produce the maximum possible degree of degradation, it would be capable of severing from one-quarter to one-third of the rubber chains. In view of these dimensions, and the fact that natural rubber normally contains difficultly removable hetero components, and is ready to take up additional amounts of oxygen, little progress can be made in the fundamental investigation of the complex molecules without a suitably accurate technique of chemical analysis, and this applies particularly to the determination of total oxygen and total nitrogen, and also to the determination of the six types of combined oxygen likely to be present in rubber, viz., hydroxylic, oxido-, ethereal, peroxidic, carbonyl and carboxylic. Unfortunately, great precision in estimation cannot be achieved without increasing greatly the rigour of the analytical technique, and perhaps it is not surprising that Midgley, Henne and Renoll's well-known high-precision method for determining carbon, hydrogen and, by difference, oxygen, still remains after five years the sole such chemical analytical method reported in the literature.
Positively Charged Latex
Authors: Coplan B. V. , Rogers S. S. , Hansen L. A. 
Published: February 2011

Abstract
Latex, like many other colloidal systems, owes its stability to a large extent to the electrical charge carried by each particle in suspension. One possible explanation of how the particles become charged is that the protein adsorbed on the rubber hydrocarbon is capable of ionizing to a slight extent, both as an acid and as a base, much in the same manner as do amino acids. In a highly basic solution the rubber particle acquires a negative charge; whereas in an acid solution the charge is positive. At some stage between strongly acid and strongly basic solutions, the ionization of the adsorbed protein layer would be as much acidic as basic, and the particle would have no net charge. This is known as the isoelectric point, and has been found to be at a pH of 4.2. At or near the isoelectric point, the latex is very unstable, and coagulates rapidly. The charge carried by the particle may, of course, be due also to adsorption of ions from solution. The latex particles are normally negatively charged, but the sign of the charge can be reversed by the addition of acid, by the presence of polyvalent cations, and more recently it has been shown that cationic soaps may reverse the charge. In a cationic soap the positive ion is a long chain, and the negative ion is a halide, sulfate, etc. The hydrophilic group attached to the long chain of carbon atoms is a quaternary ammonium, sulfonium, or phosphonium group. The authors felt that, because positively charged latex seems to have some commercial possibilities, it would be of interest to attempt to prepare latex suspensions of reversed charge of higher concentrations than those used by Blow, which were apparently around 5 per cent.
Organic Analysis of Hevea Latex. V. Ammonia, Amines and Betaines
Authors: Altman R. F. A. 
Published: February 2011

Abstract
This paper describes a method for isolating and identifying nitrogen bases, e.g., ammonia, amines and betaines, present in fresh unammoniated latex. The outline above summarizes the results. The method does not claim perfection. The author wishes to emphasize that the percentages recorded in the outline are not exact, and are given only to indicate the proportions of the respective fractions.
An Immersion Test for Rubber Compounds
Authors: Garvey B. S. 
Published: February 2011

Abstract
The immersion procedure described here is much faster than the present A. S. T. M. method, and gives results of comparable accuracy. It requires less space and less solvent. The most serious objection to it is the occurrence of anisotropic swelling due to grain in the rubber. However, there is usually more grain in manufactured articles, such as hose, than in tensile sheets. Both methods are useful chiefly for the preliminary evaluation of compounds. The final test frequently is made on the finished article under special conditions. The sensitivity of this test to grain effects suggests that its use with a good swelling agent will be a useful tool for measuring the extent of such grain in various compounds.
Rubber and Artificial Resins as “Liquids with Fixed Structures”
Authors: Ueberreiter Kurt 
Published: February 2011

Abstract
Numerous investigations, particularly in recent years, have served to throw much light on the relation between the inner structure and mechanical properties of artificial substances. The rapidly developing, industrial production of artificial materials has given considerable impetus to these investigations, since, as has often been pointed out, the solid state of organic materials represents the practical and usable form of artificial products. Basing his opinion on the fundamental researches of Tammann, Jenckel has classified many artificial substances as glasses; Houwink and others have seen in colloidal structures certain fundamentally important principles; and Kuhn, starting from purely theoretical reasoning, has explained rubberlike elasticity on a basis of molecular kinetics. In renewing the study of the freezing of liquids, an idea was developed which proved to be very helpful in guiding further research, and represented a step toward a better understanding of earlier theories. This new point of view will be discussed in the following pages.
Study of Elastic Relaxation by a Resonance Method
Authors: Mikhailov G. , Kirilina V. 
Published: February 2011

Abstract
The present work gives the results of measurements of the modulus of elasticity and the losses in ebonite by a resonance method. These magnitudes are determined as functions of the temperature for two specimens. At t=19°C, the resonance frequency of one of the specimens was 2784 Hz, of the other 1145 Hz. At these frequencies and higher temperatures ebonite is highly elastic. It is shown that the transition to this state at sound frequencies takes place at a temperature 47° C higher than by the static method.
The Tear Resistance of Rubber Compounds
Authors: Patrikeev G. A. , Melnikov A. I. 
Published: February 2011

Abstract
1. An improved method of measuring tear resistance was developed. The samples which were examined were cut in the direction of stretching. 2. The relation between tear resistance and time of vulcanization was investigated. 3. The tear resistances of synthetic and natural rubbers were compared. 4. It is shown that the tear resistance of samples of natural and synthetic rubber depends on the depth of the initial cut. With short cuts, natural rubber has a higher tear resistance than synthetic rubber, but this difference decreases as the cut is made longer. 5. It is established that the tear resistance of thin rubber specimens is smaller than that of thicker specimens. 6. The mechanism of tear resistance is discussed. Factors such as deformation are considered.
Some Physico-Chemical Properties of Carbon Blacks
Authors: Patryn T. , Pilat S. 
Published: February 2011

Abstract
A study was made of the adsorption of carbon tetrachloride vapor by various types of blacks, and data were obtained on the heats of wetting of blacks by carbon tetrachloride. A study was made of the fat coefficients and the points of spontaneous combustion of various types of blacks. It was found that active blacks can be distinguished from inactive blacks by their powers of adsorption of carbon tetrachloride and also by their heats of wetting. There is no way of telling by its fat coefficient whether a black is of value in rubber. The point of spontaneous combustion gives an approximate idea of the origin and formation of a black. Data on electrical conductivity have thus far not provided any basis for classifying different types of blacks.
Solvation in Dispersed Systems. XII. Influence of Surface-Active Substances on the Structure of Rubber Fractions
Authors: Margaritov V. , Serebryannikova L. 
Published: February 2011

Abstract
We have previously shown that the addition of nitrogen-containing compounds to sols of butadiene polymers results in the development of colloidal structures. To explain the mechanism of this action, the effect of adding similar compounds to fractions of crude rubber of varying degrees of aggregation was studied. These active substances, when dissolved either in low molecular weight fractions of the polymer or in a mutual dispersing medium, become adsorbed on the rubber micelles, change the equilibrium between the fractions, and modify the properties of the colloid. The molecular nature of the dispersing medium has a marked effect on the interaction between the polymer and the active substances. The data obtained by us are shown in Table I.
Intermolecular Forces and Mechanical Behavior of High Polymers
Authors: Mark H. 
Published: February 2011

Abstract
In order to connect the mechanical properties of high polymers with their fundamental architecture, several structural characteristics must be considered. There is, first, the average molecular weight or the average polymerization degree of the substance, which varies between 20,000 and 1,000,000 or between 100 and 5000, respectively. There is the chain-length distribution curve, which describes the heterogeneity of the material, and is comparatively narrow in some cases and fairly wide in others. There is the chemical nature of the monomer, which can be a hydrocarbon, an alcohol, ester, ether, amine, acid, nitrile, etc., so that the polymer can have very different chemical characteristics. There are, finally, the intermolecular forces between the chain molecules, which are a consequence of the chemical nature of the monomer, and which, together with the flexibility of the chains, have a preponderant influence on mechanical performance.
Theory of Rubber Elasticity for Development of Synthetic Rubbers
Authors: James Hubert M. , Guth Eugene 
Published: February 2011

Abstract
Two cardinal problems exist in connection with the production of synthetic rubbers: (1) choice of the type of synthetics, necessary raw materials, and methods of production, and (2) evaluation of the products obtained. The most important and characteristic property of synthetics (and of natural rubbers) is their long-range reversible elasticity.