bluuebunny/crossref_metadata_2025_split huggingface dataset:
History of the Division of Rubber Chemistry of the American Chemical Society
Authors: Osberg E. V. 
Published: February 2011

Abstract
After long years of experience, the rubber industry of today has come to realize the true worth of the chemist and the value of the interchange of scientific knowledge and coöperation in research. Early meetings and discussions held by the Division of Rubber Chemistry of the American Chemical Society and its predecessor, the Rubber Section, were influential in dispelling early ideas as to the value of the chemist and in breaking down the barrier of secrecy in the rubber trade. The chemistry of rubber during the past two decades has undergone a tremendous growth, and the Division through its many activities has played an important role in disseminating knowledge that has been gained from laboratory research. THE EARLY RUBBER CHEMIST Before the turn of the twentieth century, the rubber industry had little or no knowledge of the chemist or what he might accomplish. Funds for research were generally withheld, with no quick profits in sight as a result of these expenditures. Among the comments of rubber manufacturers of that time were: “I have no use for chemists, druggists and apothecaries”; “I would give more for the guess of my old superintendent than all the certainties of the best chemist on earth”; “I had employed chemists but their cost to the company had been greater than any value received from their work.” In 1899 the chemist, Arthur H. Marks, invented the alkali reclaiming process, and in 1906 George Oenslager discovered organic accelerators. Rubber technology was being revolutionized by the chemist, and larger profits were in sight. The tight grip on the purse strings became loosened somewhat, and money was being cautiously expended on research. Practical and immediate results which could be translated into hasty profits were the principal aims. Little encouragement was afforded those who wanted to tackle fundamentals. Competition was keen among manufacturers; the rubber industry was growing rapidly, and no time or money was available for abstract reasoning or for “profitless” research enterprises. Rubber manufacturers were quite willing for their chemists to meet with chemists of other companies provided they did not divulge any of the firm's “secrets”. With most of those attending these early meetings in the role of listeners, little was accomplished in furthering the knowledge of rubber chemistry through the exchange of ideas. Such was the problem during the life of the Rubber Section and through the earlier years of its healthier successor, the Division of Rubber Chemistry.
The Crystallization of Weakly Vulcanized Rubber by Pressure
Authors: Thiessen P. A. , Kirch W. 
Published: February 2011

Abstract
Crystallization can be brought about in weakly vulcanized rubber by the method described by Thiessen and Kirsch for natural rubber. When samples of this type of vulcanized rubber were exposed to x-rays below + 6° C, but not under pressure, then Debye-Scherrer diagrams corresponding to those of a crystallized latex film were obtained. To determine the influence of pressure on these vulcanizates, samples were subjected to pressure on all sides in the chambers of the pressure apparatus described in the earlier work. After having been exposed for 100 days the sample which had been kept at + 6° C under 30 atmospheres' pressure showed a very marked Debye-Scherrer diagram, whereas samples kept at the same temperature but at normal pressure showed only the halo of an amorphous substance. Consequently pressure has an influence on the crystallization of vulcanized rubber as well as of raw rubber. The melting point of the crystalline phase lies between + 11° C. and +13° C. Obviously then an increase in pressure raises the temperature range of supercooling.
Tensile Tests of Plantation Rubber
Authors: Slbiriakoff I. 
Published: February 2011

Abstract
The investigation which has just been described can be summarized as follows: (1) A technique for the commercial testing of plantation rubber has been developed which is simple and precise, and by means of which it is possible to reproduce control tests, a feature which is indispensable if rubber is to be sold on a basis of quality rather than superficial appearance. (2) The tentative specifications for testing rubber drawn up by the Crude Rubber Committee of the Division of Rubber Chemistry of the American Chemical Society have been found acceptable as a basis for this testing procedure. (3) It has been found necessary, however, to revise the specifications of the Crude Rubber Committee in some ways and to amplify them, so that they fulfill the three conditions described above and also conform to the particular working conditions of laboratories in the tropics. The revisions to the Crude Rubber Committee specifications include: (1) The use of an autoclave for vulcanizing in open steam. (2) A mill roll temperature of 65° C instead of 70° C. (3) A definite, fixed weight of batch, containing 200 grams of rubber, plus accessory ingredients. (4) A temperature of 25° to 30° C during testing. (5) The use of ring test-specimens instead of dumb-bell specimens.
The Viscosity of Preserved and Concentrated Latex. Part I. Relationship between Dry Rubber Content and Viscosity
Authors: Rhodes Edgar , Smith H. Fairfield 
Published: February 2011

Abstract
In the October 1939 issue of Rubber Chemistry and Technology, on pages 655–664, is an article of the above title by Edgar Rhodes. Since the time of its original publication in the India-Rubber Journal, in January 1939, the work has been revised and published in the Journal of the Rubber Research Institute of Malaya, Vol. 9, pages 171–188 (Communication no. 241), December 1939. The attention of Rubber Chemistry and Technology has been called by Mr. H. J. Page, Director of The Rubber Research Institute of Malaya, to the importance of certain revisions in Part I of the work. Mr. Page points out, for example, that “the authors have evaluated separate relationships for ammoniated field latex and for centrifugal concentrates, thereby revising the estimates of the average viscosity of latex of varying dry rubber content at 30° C.” These new data are given in Tables I and II. The discussion on pages 657 and 661–663 of the same issue of Rubber Chemistry and Technology has been altered considerably, and therefore is reproduced in full here.
Analysis of Proteins Present in Hevea Latex
Authors: Altman R. F. A. 
Published: February 2011

Abstract
To analyze the proteins present in rubber-free serum obtained by coagulating latex for the preparation of sheet rubber, the method described by Brazier was adopted. Inasmuch as this method is not wholly satisfactory, particularly in the humid atmosphere of the tropics, is was improved in several ways. Besides several amino acids, some interesting byproducts were isolated, among others a yellow-reddish thick oil, and other ether-soluble substances. Scheme G outlines the results attained. The properties of the products isolated will be discussed in a later publication.
Hevea Latex Sludge. Existence of a Sludge Fraction in Fresh Unpreserved Latex
Authors: McColm E. M. 
Published: February 2011

Abstract
Bruce recorded the results of analyses of the ash of certain crude rubbers, among them of evaporated latex. He found the sample investigated to contain 5.8 per cent MgO and 24 per cent P2O5. It is evident that ammoniation of a latex containing such ions would result in the formation of insoluble MgNH4PO4.6H2O. Hauser refers to this phenomenon, stating that the precipitated salt settles to the bottom of the container. This precipitate, sometimes containing occluded rubber, has been known in the plantation industry as latex sludge, and has constituted a fouling problem in storage containers. The presence of a sludge fraction in fresh unammoniated latex, just as it is produced by the tree, has not been generally recognized. Van Harpen concentrated fresh unpreserved latex by centrifuging and, on opening the centrifuge, observed a sludge deposit in the bowl. He records that this sludge darkened rapidly and states that it was rubber-free and friable. As a beginning in a study of latex desludging procedures in this laboratory, a quantity of the sludge was obtained and analyzed. The data obtained are reported here.
Ultraviolet Irradiation of Rubber
Authors: Srinivasan P. S. 
Published: February 2011

Abstract
The absorption of light by rubber when dissolved in polar and non-polar solvents was measured before and after exposing the solutions to ultraviolet light in the absence of air. It was found that irradiation with ultraviolet light makes rubber more transparent when in non-polar solvents and less transparent when in polar solvents. The state of rubber in solution is reviewed in the light of present-day knowledge, and a tentative explanation of the absorption phenomenon is suggested on the assumption that the rubber molecule in a polar solvent is depolymerized by the field of the solvent molecule and that ultraviolet light produces both polymerization and depolymerization of rubber, according as rubber initially is in a low or high state of polymerization. A probable support to this concept from measurements of viscosity is indicated.
Mechanism of Polymerization Reactions
Authors: Melville H. W. 
Published: February 2011

Abstract
The peculiar properties possessed by molecules consisting of long chains of atoms linked together by primary valence forces are as yet imperfectly understood. Both naturally occurring and synthetic substances of this type are now familiar in a large variety of forms, of which rubber and cellulose are well-known examples of the former type. The problem may be attacked from two points of view. On the one hand by an investigation of the properties of large molecules something may be learned about molecular structure; on the other an attempt may be made to build such molecules synthetically to a predetermined pattern so that a correlation between structure and behavior may be established. This article will be solely concerned with the second aspect of the subject. Here the general problem is to carry out the synthesis under rigidly controlled conditions in order that the precise mechanism of molecule building may be determined with absolute certainty.
The Stability of Chlorinated Rubber and Its Fractions
Authors: Hoekstra J. 
Published: February 2011

Abstract
(1) In ultraviolet rays decomposition occurs in the upper surface of a layer of chlorinated rubber. (2) The amount of chlorine split off from a common commercial specimen of chlorinated rubber when heated dry for 30 days at 100° C was about 0.25 per cent. For the greater part, the chlorine was free of hydrogen chloride. (3) The rate of decomposition when dry heating was applied at 100°, 130° and 150° C leads to the conclusion that the speed of reaction diminishes rapidly at degrees below 100° C until there is soon no reaction at all. (4) The amount of chlorine split off when chlorinated rubber was heated in water at 100° C was about five times as large as when dry heating was applied. (5) From the curves indicating the amount of chlorine split off during “wet”and “dry”heating at 100° C, it is possible to calculate quantities which may be regarded as the maximum amounts of chlorine which can be split off from the respective specimens. These amounts are twice as large when the chlorinated rubber is heated wet as when dry heating is applied; with a given normal specimen about 1.5 per cent was obtained in wet heating. Only in one of eight specimens was a greater quantity found, viz., 3 per cent. (6) In a certain specimen 10 per cent of carbon tetrachloride was found. The splitting off of chlorine is not caused by decomposition of this substance.
Applications of the Manometric Method for Measuring the Oxidizability of Rubber. Oxidizability and Aging in the Geer Oven
Authors: Dufraisse Charles , Le Bras Jean 
Published: February 2011

Abstract
In summary, the changes which take place in the mechanical properties of a rubber mixture when it is aged in a Geer oven, and which are evident by dynamometric measurements, are closely related to the proportion of oxygen absorbed by the sample. It is therefore much more practical and convenient to measure its oxidizability after only a few minutes' aging, using a sample of any shape whatsoever, and a weight of approximately one gram. As far as any particular standard industrial mixture is concerned, there is no good reason for not conforming to the customary practice of rubber technologists of expressing aging on the basis of loss in tensile strength. In this case the only thing necessary to do is to calibrate the manometer in kg. per sq. cm. after having established the curve relating oxygen absorbed to loss in tensile strength.
Some Consequences of the Electrical Double Layer in Rubber Technology
Authors: Twiss D. F. , Carpenter A. S. , Amphlett P. H. 
Published: February 2011

Abstract
The effects of the electrical double layer in connection with rubber manufacturing processes have, in recent years, become of rapidly increasing technical importance. In the last two decades remarkable developments have occurred in the application of aqueous dispersions of rubber, or of rubber-producing materials. The characteristics of these dispersions are largely dictated by the electrical double layer and adsorbed material associated with it. These aqueous dispersions may be of several distinct types, viz.: (1) natural dispersions of natural rubber, in particular the latex of Hevea brasiliensis; (2) artificially prepared dispersions of natural rubber; (3) dispersions of artificial or synthetic rubber in which the rubber-like material has been formed from predispersed parent material; (4) artificially prepared dispersions of artificial or synthetic rubber. It is convenient to discuss these in substantially the reverse order to that in which they have just been enumerated. Artificially prepared dispersions of synthetic rubber-like materials are latexlike fluids which can be applied in the same way as natural latex to manufacturing purposes, and not only impart any advantageous features of the dispersed material, but also possess a potential advantage in that dispersing agents can be selected which are resistant to attack by, or to growth of, bacteria or moulds, with consequent enhancement of stability, or which are favorable to the water resistance of the final product.
Hevea Latex. Correlation of Nitrogen and Ash with Total Solids Content
Authors: McGavack J. , Rhines C. E. 
Published: February 2011

Abstract
The purpose of this paper is to report primarily the correlation of nitrogen and ash with the total solids of Hevea latices. In addition it is desired to show that the nitrogen in the rubber, prepared by acid coagulation, depends on the original total solids content of the latex. A further purpose is to show that the residual nitrogen adsorbed, dissolved in, or directly associated with the rubber phase has a constant value, independent of the concentration of nitrogen in the aqueous phase. It is believed that the proper knowledge of such relations will be helpful in the preparation of better crude rubbers. Arisz made a study of the nitrogen content of latex. His work was directed to observing the change in the nitrogen content of latex as influenced by the use of various systems of tapping, both with regard to time and location of the cut. His results indicate that there is a relation between the total solids content and the nitrogen value. Using his data on tree 1 and plotting the nitrogen as a percentage of the total solids against the total solids content of the latex (Figure 1), we find that the nitrogen content of the total solids is roughly inversely proportional to the total solids content of the latex. When Arisz's data were plotted so that the nitrogen content was a percentage of the whole latex, a line parallel to the x-axis seemed to result. Following the leads obtained from the work of Arisz, we decided to determine the nitrogen content of latex, from particular areas on our plantations, obtained by the usual tapping methods. We also decided, while these samples were available, to see how the ash varied with the total solids content of the latex, and to determine how the nitrogen would be apportioned when latices of various total solids content were coagulated.
Separation and Identification of Lecithins from Hevea Latex
Authors: Altman R. F. A. , Kraay G. M. 
Published: February 2011

Abstract
To identify completely the phospholipids, which according to several authors may occur in Hevea latex, we separated in a very simple way a butter-like substance, which really contains phospholipids. The results of qualitative analysis justify the positive conclusion that this substance contains lecithins composed of glycerophosphoric acid, choline and the fat acids: palmitic acid, stearic acid, arachidic acid, oleic acid and linoleic acid. A glycoside also was shown to be present in the raw material. We found the content of phosphorus, nitrogen and fat acids to be 1.58, 0.54 and 84.1 per cent, respectively. In purifying the crude material by means of fractional precipitation with acetone from the ether solution, we obtained a nearly colorless gum which contained 2.35 per cent phosphorus, 1.05 per cent nitrogen and 61.3 per cent fat acids. It is stated that the purification is accompanied by a considerable loss of fat acids, the latter remaining in the acetone-ether solution.
A Contribution to Knowledge of the Creaming Process
Authors: van Gils G. E. 
Published: February 2011

Abstract
Creaming of latex is a process which is extensively employed, partly because good creaming agents have been developed and partly because of the constantly increasing demand for concentrated latex. Knowledge of the mechanism of creaming is not in proportion to the great practical importance of the process. It still happens too frequently that unexpected variables or phenomena, for which the laboratory investigator can offer no explanation, are encountered. In the present paper we present the preliminary results of tests carried out at the West Java Experiment Station. For a general survey of creaming processes, reference should be made to a recent paper by Kraay. The object of the present paper is to enquire more deeply into various phenomena which are discussed briefly in the paper cited above. Unless otherwise stated, the tests to be described were made with konjak flour, abbreviated here to K flour.
Elastic Recovery and Plastic Flow in Raw Rubber
Authors: Treloar L. R. G. 
Published: February 2011

Abstract
In considering existing information on the mechanical properties of raw rubber, it is not generally possible to distinguish between the effects of elastic and of plastic deformation. In the experiments described great care was taken to secure the complete removal of elastic strain, after stretching to various extensions at different temperatures. The plastic flow increased to a maximum with increasing elongation and fell again at higher elongations, an effect attributed to the increase of crystallization with increasing extension. For rubber held extended for one hour at 25° C the flow was never greater than 2% of the original extension, and for extensions greater than 440% or less than 130% it was negligibly small. Curves showing the decay of tension at constant extension, and the recovery of length after stretching, in conjunction with the observations on plastic flow, are interpreted in terms of a theory proposed by Busse, according to which the rubber molecules are held together at certain points by cohesional linkages of low energy, some of which are broken down during stretching.
A Study of Polymers. III. Technique of Mechanical Tests of Vulcanizates of Rubber and Plastics
Authors: Gurevich G. I. , Kobeko P. P. 
Published: February 2011

Abstract
1. From the point of view of mechanical properties, the special attributes of highly polymeric substances, including rubber vulcanizates, are clearly defined by their reversible highly elastic deformation as a function of time. The time required for attaining this deformation within a given interval of time varies practically from zero to infinity. 2. Disregard of the temperature and time relation of deformation of highly polymeric substances leads to erroneous conclusions regarding their industrial working properties, and is the cause of the unsatisfactory results obtained by conventional methods of investigation. 3. The effect of increased degree of vulcanization on the mechanical properties of rubber is manifest in a decrease in complete elastic deformation and shift of the temperature-apparent modulus (inverse to the deformation in a given time) curve toward higher temperatures. 4. Conventional ideas of the plastic (irreversible) and elastic deformation of solid materials, when applied to highly polymeric substances without concern for the laws governing their deformation, lead to erroneous conclusions regarding the existence of specific properties of individual substances, e.g., ebonite and synthetic resins, and mistaken hypotheses regarding structural changes during their deformation. In the present communication, this is illustrated by studies of various investigators. 5. Conventional methods of studying thermal stability and brittleness, as well as other methods of testing, of highly polymeric substances frequently do not make it possible to evaluate the actual technical utility of materials within intervals of temperature encountered in service and they should be critically reëxamined with regard to the relations between deformation and reversibility, time and temperature.
Swelling of Synthetic Rubbers in Mineral Oils. Effect of Variation in Aniline Point of Oils
Authors: Carman F. H. , Powers P. O. , Robinson H. A. 
Published: February 2011

Abstract
1. There is a marked difference in the swelling caused by different mineral oils on compounds made of any synthetic rubber, such as Neoprene, Thiokol, or Perbunan; the arrangement of the oils by swelling effect tends to remain the same for the synthetic compounds tested. 2. The change in volume is rapid on initial immersion and then gradually approaches equilibrium, except in the case of those systems where marked swelling is encountered. 3. The aniline point, determined at a concentration of equal parts of aniline and oil by weight, appears to be a characteristic of mineral oil which will indicate the probable swelling effect on synthetic rubber compounds. The 50 per cent aniline point is more conveniently determined than is the gravity index, and appears to be at least equally reliable. 4. The viscosity rating of a mineral oil is not a satisfactory criterion of its tendency to swell rubberlike compositions, and should not be the sole description of an oil for acceptance specification testing of synthetic rubber products.