bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rubbone
Authors: Stevens H. P. , Stevens W. H. 
Published: February 2011

Abstract
Of all the reactions which natural rubber undergoes, oxidation next to vulcanization, may be said to rank in the first place. For not only does the life and usefulness of all raw and vulcanized rubber depend on the course of this reaction, but attempts to create useful oxides may be regarded as based on the same reaction. It has already been shown that, by the catalytic oxidation of rubber, solutions of greatly reduced viscosity and/or increased concentration are obtainable. Thus, a 50 per cent solution of rubber which will flow at normal temperatures can be made by incorporating 2.5 per cent of cobalt linoleate on the mill, subsequently “letting down” in white spirit or other solvent by means of an internal type of mixer. The mechanism of the oxidation of rubber is a complex and still incompletely solved problem, but a reasonably acceptable explanation of this reduction in viscosity is that it is due to a disaggregation of the rubber micelle, whereby a very small amount of chemically combined oxygen is enabled to effect a very large physical change in the character of the colloid. This change is promoted by catalysts, such as the ordinary paint driers, and there appears to exist an analogy between the drying of paint and the disaggregation of rubber solutions, but it is interesting to note that whereas copper soaps have substantially no effect on the drying of linseed oil, they do reduce the viscosity of rubber solutions appreciably. Solutions of rubber containing catalysts have been “blown” by bubbling air, oxygen or ozonized air through them while maintained at raised temperatures by suitable means. The experiments covered a great variety of conditions, including different solvents, different types and concentrations of rubber and catalyst, mixed catalysts and a variety of temperatures and blowing conditions. It was found that under suitable conditions the oxidation of the rubber could be taken to a stage where the cobalt linoleate itself became oxidized and was precipitated from the solution. After filtering, the resulting solutions were evaporated to yield an oxidized rubber resin. A standard procedure has been developed for the production of this rubber resin, or “Rubbone” as it is conveniently termed, as follows. A solution of milled blanket crepe in white spirit is made by dissolving 20 parts by weight of rubber in 80 parts by weight of solvent, adding 0.5 part of cobalt linoleate, and aerating at 80°C. until a sample drawn off from the bulk shows a quick separation of sediment and a clear supernatant solution of the resin. The solution is clarified by “tanking” or centrifuging and is then distilled by steam or in vacuo to separate the resin.
Properties of Latex-Insulated Wire
Authors: McGavack J. 
Published: February 2011

Abstract
In 1863 latex was proposed and actually used to insulate wire. Siemens had the happy thought of employing this material to cover conductors and actually went so far as to obtain patent protection for his idea. From that time until recently, there has been practically nothing accomplished in the manner directed by Siemens. In fact, no commercial insulation material resulted from the idea proposed in the middle of the nineteenth century. It is not hard to see why such a plausible idea was abandoned. The insulation obtained in the manner disclosed by Siemens was not nearly as good as the other known methods for insulating wire. Conductors covered by the method then proposed could not be used in water or where any moisture was present. There were too many water-soluble materials in the latex; and as no method was known at that time to remove these materials from latex without coagulating the latex itself, no further development was accomplished.
Isoprene and Rubber. Part 44. Viscosity Measurements of Squalene and Hydrosqualene Solutions
Authors: Staudinger H. , Mojen H. P. 
Published: February 2011

Abstract
The physical properties of highly polymerized substances, which are composed of fiber molecules, depend on the lengths of the chains of these fiber molecules. Thus tensile strength, elasticity, tendency to swell in solvents, and above all viscosity, are dependent on the length of chain of the particular substance. Among the substances, the properties of which vary thus, are rubber, gutta-percha, and balata. Since the length of fiber molecules can vary within wide limits, such physical properties as those mentioned above show wide variations in the case of rubber, gutta-percha, and balata. This is evident for example by a comparison of the properties of unmasticated rubber, which consists of long fiber molecules of a degree of polymerization of 2000, with the properties of masticated rubber, the greatly dissociated molecules of which have a degree of polymerization of only 500. The determination of the length of the fiber molecules is therefore of great importance in the case of highly polymerized substances. It has already been proved in past experiments with members of a series of homologous polymers, i. e., of substances the macromolecules of which have the same basic structure and differ only in length, that the molecular weights can be determined from viscosity measurements. This determination is based on the fact that there is a general relation between the specific viscosity and the length of the dissolved molecules, which can be expressed by the formula:
The Effect of Pigment Particle Size on Some Physical Properties of Rubber Compounds
Authors: Barnett C. E. 
Published: February 2011

Abstract
The importance of flow in rubber on the reinforcing properties of pigmented systems has been emphasized by Park. He suggests that: (1) in the presence of a finely divided pigment, the flow which occurs when a piece of rubber is stretched takes place in the capillary spaces between the pigment particles; (2) some modification of the laws of liquid flow may govern the behavior of rubber with reference to pigments embedded in it, and (3) the forces causing increased stiffness in pigmented rubber compounds are similar to those causing increased resistance to flow of liquids iii tubes of capillary dimensions. Thus increasing fineness of subdivision and the resulting fineness of capillary spaces between the particles should be accompanied by an increase in reinforcing properties. It would be desirable to study the actual stresses around pigment particles in rubber under strain, but so far no suitable microscopic set-up has beem devised. A few years ago the writer, resorting to analogies, measured the strains and stresses around large particles with the assumption that the strains would be relatively the same with small particles. For this study, holes of the desired size and shape were cut in strips of calendered but uncured rubber and fitted with pieces of an uncured semihard rubber compound. After vulcanization squares were marked on the tensile sheets as shown in Fig. 1.
Heat Generation and Anisotropy of Rubber Compounds in the Flexometer
Authors: Havenhill R. S. 
Published: February 2011

Abstract
Data have been presented to show that it is possible for rubber compounds when tested in the flexometer to exhibit simultaneously a plastic flow in one direction, and a marked stiffening in another direction, resulting from the elimination of plastic flow by rapid flexing. Both effects are shown to be due mainly to heat generation or temperature effects. The rate of heat generation depends in part on the anisotropy of the rubber, which is much greater than is indicated by some of the ordinary physical tests such as tensile strength, resistance to tearing and to abrasion. The theory that the degree of anisotropy is influenced by the shape and orientation of the pigment particles and of the anisotropy of the rubber itself has been in a measure experimentally verified.
Bacterial Decomposition of the Rubber in Hevea Latex
Authors: Spence D. , Van Niel C. B. 
Published: February 2011

Abstract
A RECENT communication (6) has shown by several different means that rubber present in the living plant actually disappears under seasonal and other conditions in the life of the plant, and that it can, therefore, no longer be regarded as an excretory product of metabolism of no physiological value to the plant. The results recorded were obtained in a study of the rubber content of Parthenium argentatum, but they will undoubtedly be found to hold for Hevea brasiliensis when suitable methods of investigation are developed for the latter. The importance of these findings in relation to the economic development of rubber is obvious and far-reaching. They have already been applied in the cultural development and exploitation of Parthenium argentatum. On the scientific side they suggest a more intimate study of the behavior of the rubber hydrocarbon towards oxidation-reduction processes occurring within the living plant and to the effect of such agencies on the rubber itself in vitro. That rubber is readily attacked by oxidizing agents in general is now well known. But even the classical researches of Harries on the products of decomposition of the rubber hydrocarbon by means of ozone (1) have thrown little light on the ways and means by which the rubber in the plant is first produced and thereafter broken down and utilized in its cycle of yearly development. This is not surprising when we consider the reagents heretofore employed and the drastic character of the decompositions effected by them.
A New Rubber Particle Count in Hevea Latex
Authors: Langeland Earle E. 
Published: February 2011

Abstract
SO MUCH confusion has grown up in the literature concerning the number of rubber particles in Hevea latex that at the present time there exists a thousandfold error in the currently published reports (1, 3, 8) of the one original determination of this number. Harries (4), Hauser (5), and Noble (8), each reporting the original work of Henri (6), give a count of 50,000,000 particles per cubic centimeter of latex, Harries not specifying the concentration, while Hauser and Noble indicate it to have been 8.7 per cent solids. On the other hand, Dubosc and Luttringer (2), also reporting the work of Henri, record a count of 50,000,000 particles per cubic millimeter in latex of unspecified concentration. The original paper of Henri (6) reported that he had found an average of 50,000,000 particles per cubic millimeter of latex having a specific gravity of 0.973 and containing 8.7 grams of solids per 100 cc. Preliminary counts undertaken by the author with a view to developing a rapid microscopic method for the determination of the dry rubber content of latex indicated that the results of Henri were considerably low. Since the number of microscopically visible particles is a fundamental property of latex, it was felt that a redetermination of this number would be of value.
Determination of Guanidines in Rubber Stocks and Consumption of Guanidines during Cure
Authors: Humphrey Bingham J. 
Published: February 2011

Abstract
QUANTITATIVE determinations of various accelerators that may be present in vulcanized rubber stocks are necessary, not only for fundamental investigations into the mechanism of acceleration, but also for routine control analyses and the examination of unknown stocks. The determination of any organic material in vulcanized rubber stocks is beset with numerous difficulties, however, and reliable methods are scarce. For accelerators, the only ones described in the literature are the now generally employed copper oleate method for mercaptobenzothiazole and an extension of Callan and Strafford's (1) picric acid method for guanidines, both described by Wistinghausen (2). Using these two procedures, Wistinghausen made an extended investigation of the consumption of mercaptobenzothiazole and of diphenylguanidine (D. P. G.) during cure. Considerable difficulty was encountered in this laboratory in the use of Wistinghausen's method. Especially with di-o-tolylguanidine (D. O. T. G.) stocks, the results were highly variable and the proportion of guanidine recovered seemed to be much smaller than that recovered by Wistinghausen from similar stocks. As a test of both the method and the technic, an uncured di-o-tolylguanidine tread stock was analyzed, since it was believed that, in this case, an effective procedure should account for substantially all of the guanidine put into the stock. The result was that little or no more guanidine was recovered from the uncured stock than from the same stock at an optimum cure. Guanidine recoveries from either one ranged from 30 to 50 per cent.
The Natural Stabilizers of Latex
Authors: Stevens W. H. 
Published: February 2011

Abstract
The paucity of information regarding the properties of natural rubber and allied latices, other than Hevea Braziliensis, is surprising. While great attention has been paid to fresh and preserved Hevea latex, little or nothing appears to have been done recently with other rubber or rubber-like (e. g., gutta, balata, etc.) latices. Indeed, many authors of papers on rubber latex preface their articles with a statement that only Hevea latex will be considered, other latices being of no commercial interest. It is likely, however, that a careful scientific examination of latices of botanical origin other than Hevea would yield much information of practical importance to the application of Hevea latex, although these latices may not be obtainable at present in commercial quantities. For instance, the fact that certain of these latices require no preservative indicates that they contain a natural stabilizer greatly superior to any substance occurring naturally in Hevea latex, or used in its industrial applications. The identification and application to Hevea of such natural stabilizers represents, therefore, an important technical research. Though many references to latices other than Hevea are to be found in the literature, these are mostly somewhat old, and more often than not predate the advent of the rubber plantation industry, while more recently the attention so strongly focused on Hevea latex has caused the latices of other botanical origin to be entirely neglected. The data given below for Abiarana gutta-percha latex may, therefore, be of some interest.
Consumers' Crude Rubber Requirements
Authors: Sackett George A. 
Published: February 2011

Abstract
In this brief summary of requirements, much has been left unsaid. It is difficult to be specific, for the requirements of the rubber manufacturing industry vary widely. It is hoped, however, that this presentation will focus some attention on the subject, and that eventually a more definite idea of the requirements of the various consumers will be presented so that plans of research in rubber-producing parts of the world can be made to develop the products needed by the consumer. This would also aid in the development of closer contact by both producer and consumer, which is desirable in any industry. The formulas suggested are open to criticism and it is hoped that if those suggested are not adopted as standard, others more generally accepted will be evolved so that there may be a universal agreement on the method of testing certain properties of rubber. It may be argued that a rubber which combined all the properties mentioned would be ideal, but it is well to set up an ideal to strive for, so that through the collaboration of producer and consumer, it may perhaps be realized.
A Fatigue Cracking Test for Tire Tread Compounds. Some of the Laws of Fatigue
Authors: Rainier E. T. , Gerke R. H. 
Published: February 2011

Abstract
AN IMPORTANT factor in the service rendered by a tire tread is its ability to resist cracking. Cracking of tire treads in service may be classified into two kinds or phases—the initiation or start of cracks, and the growth of cracks or cuts once started—and the two phases must be differentiated. Nearly all tires in service soon develop small cracks or “checking” due to the action of ozone in the atmosphere (9), and may suffer cuts due to sharp objects on the road. In many cases such cuts and ozone cracks may be harmless, but if the cracks grow too rapidly they will extend to the carcass before the tire is worn out (4). We define the growth of cracks under the influence of mechanical action as fatigue cracking. The quality of rubber in respect to its resistance to fatigue cracking can be improved by addition of antioxidants (3, 7), and by such factors as the proper choice of accelerators (4), the proper balance of fillers (1, 3), and the proper cure. The quantitative evaluation of such chemicals and compounding ingredients in the laboratory depends upon the validity and precision of a test. It is the purpose of this paper to describe a laboratory test which has been found to correlate with shoulder cracking in tires, and to present data from which certain laws of fatigue cracking have been deduced.
Plasticity and Elasticity, with Special Reference to Unvulcanized Rubber
Authors: Hoekstra J. 
Published: February 2011

Abstract
When working in the field of elastic and plastic properties of plastic materials such as unvulcanized rubber, one is confronted with the fact that there is very little reliable knowledge in that field. Some time ago Prof. J. M. Burgers, in an address before the Foundation of Biophysics, gave a fundamental and extended explanation of the theory of plasticity and its relation to elasticity. Previous to experimental investigations of plasticity, elastic-plastic behavior was assumed to be so simple that it could be reproduced by means of a system of steel springs and pistons of constant friction. It was thus clearly a problem of hydrodynamics and mechanics. Up to the present time, the mechanical properties of highly polymerized substances have remained a mystery to research workers. In an investigation of polymers of high molecular weight, Meyer, Susich, and Valko proposed that the elasticity of these substances depends on the transverse motion of the long molecules, and is thus closely analogous to the elasticity of gases. Their strong argument in favor of this is the fact that the elasticity of rubber, for example, has a positive temperature coefficient, which is in agreement thermodynamically with their suppositions. It is now known from the great difference between the mechanism of the elasticity of rubber and of metals, and also from the stress-strain diagram of rubber (the well-known S-curve), that it is very improbable that the properties expressed by means of pistons and springs can be correctly applied to a substance like rubber. The same holds true for other highly polymerized substances. In spite of the foregoing, it is not surprising that the measurements of Scott, of Peek, and of Houwink showed close agreement with the theory, at least in a great number of fields of flow which were investigated. The agreement always holds true for relatively large shearing forces, viz., when the shearing forces are great compared with the intramolecular or thermodynamic forces. When the latter forces cease to operate, there appears a flow which is generally known as viscous flow. For smaller shearing forces, however, the change in shape and the plastic flow are not measurable by the methods applied by the above-named authors.
Rationalization of the Hardness Testing of Rubber
Authors: Scott J. R. 
Published: February 2011

Abstract
The object of this paper is to draw attention to the present unsatisfactory state of the hardness testing of vulcanized rubber and the need for standardization of this test, and also to present some results of an investigation into the theoretical basis of hardness testing and the practical significance of hardness measurements. In this paper the word “hardness” will be used in the sense generally accepted in the rubber industry, that is, to denote resistance to indentation. The most commonly used types of hardness tester measure hardness in terms of the depth of the indentation made by a rigid ball or blunt pin pressed into the rubber by either a dead weight or a spring. The reading given by such an instrument, usually termed the hardness number, must depend on several variable factors, namely (1) the dimensions of the ball or pin; (2) the weight used to press it into the rubber, or the compression characteristics of the spring in the case of spring-loaded instruments; (3) the direction of the scale of the instrument, i. e., whether the reading increases with the depth of indentation, as in the Pusey-Jones Plastometer, or in the reverse direction, as in the Durometer; (4) the units in which the indentation is measured, i. e., whether in 100ths of a millimeter, 1000ths of an inch, or arbitrary units. In addition to these factors relating to the instrument, the reading must also depend on the dimensions of the rubber test-piece, especially its thickness, the nature of the rubber surface, and the period for which the ball or plunger is pressed on to the rubber before the reading is taken.
Porosity in Vulcanized Rubber
Authors: Bodger Walter H. 
Published: February 2011

Abstract
A systematic investigation has been made of the factors likely to promote porosity in vulcanized rubber. Of the methods developed for assessing the degree of porosity, measurement of the percentage decrease in specific gravity is shown to be the most satisfactory. The permeability of the sheet to moisture, the acetone extraction of aged samples, and visual examination also give some indication of the degree of porosity. Severe over-mastication, particularly on cold rolls, plasticizes rubber and increases the entrapment of gases during mixing. If the pressure applied during vulcanization is low, the volume decrease, which occurs as the rubber vulcanizes, causes further lowering of pressure; some of the entrapped gases are liberated, and as the rubber is partially set up free escape is prevented and pores are developed. The effect of over-mastication can also be produced by heat or oxidation treatment of the raw rubber. Mechanical treatment of the mix, such as sheeting from the mill at friction speed, calendering to a thick gage, or extrusion of thick articles may increase the tendency for porosity under the appropriate conditions. Softeners added to the mix produce the same effect as over-mastication in increasing porosity, whereas stiffening fillers oppose its production. When no mechanical pressure is applied during vulcanization, porosity is likely to develop, but a slight pressure may cause even worse porosity through preventing the free escape of gases during the soft stage before vulcanization commences. The degree of porosity depends on the conditions prevailing during the initial stages of vulcanization and is, in fact, a useful indication of setting up when scorching tests are being carried out. It is not influenced by the action of heat, in the later stages of vulcanization on the rubber-sulfur or oxygenated rubber complexes. Moisture, derived from the ingredients of the mix, the processing or the methods of vulcanization, increases the porosity under appropriate conditions. The use of ultra-accelerators or high-curing temperatures, tends to increase porosity of mixes liable to this defect, as the escaping gases are more completely entrapped by a rapid setting up of the rubber. Some applications of the results to methods of overcoming porosity under works conditions are given.