bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Operating Conditions on the Life of Rubber Belts
Authors: Perin R. J. 
Published: February 2011

Abstract
The variation in life of rubber belting has been a major technical problem of the rubber industry for many years. Although rubber compounds have been greatly improved, both in flexing life and aging properties, the life of belts on certain types of drives has not increased accordingly. To determine the cause of this variation, a survey was made of the performance records of belts on all types of drives. From this survey it was possible to obtain data on those drives wherein the belt life fell below the average expectancy. An analysis of this information divided these premature failures into two groups, which were designated as “external” and “internal”. The former classification includes failures due to excessive slip, high temperatures, misalignment and other detrimental operating conditions. The latter group includes those failures with no signs of external damage, and where failure involves that common condition, internal separation of the plies. A further examination of the reports on internal failures showed that practically all the drives concerned had one or more of the following characteristics: small pulley diameters, high belt tension, or high belt speed. The problem then resolved into a determination of the relative effect of these conditions on belt life.
Application of the Langmuir trough to the Study of Rubber Latex
Authors: Wren W. G. 
Published: February 2011

Abstract
When a drop of ammoniated latex is allowed to touch a cleaned water surface, it spreads rapidly and evenly at the air-water interface, none entering the bulk of the water. Microscopic examination of such a film shows that, given sufficient spreading area, the latex globules are clearly separate one from another, and form a layer one particle thick. On reducing the area occupied by the globules by compressing the film between waxed glass straight edges lying in the surface of the water, the particles are forced together until visible spaces or voids disappear. The film still appears to be one particle thick, and remains in the surface of the water. Further compression results in irregularities of the surface, which can be seen to consist of folds in the film and, on expansion, a proportion of the latex globules is found to have been forced from the surface into the bulk of the water. If a dilute solution of certain substances is used in place of water, the latex particles all remain on the surface, even under conditions of high compression. Dilute acids and solutions of divalent metal salts are found to be effective in keeping the particles in the surface but, on compression to the point where close packing of the particles occurs, the film sometimes forms a continuous coagulum and on release of the pressure, it does not expand. Solutions of a creaming agent, such as 0.1 per cent sodium alginate (Manucol V), are adequate, not only to prevent particles being forced out of the surface, but also to give films which expand readily on release of the pressure. The fact that the latex is instantly swept to one side by a trace of surface active material, such as oleic acid, confirms that the particles have not penetrated into the interior of the water.
Electrical Resistivity of Rubber Compounds
Authors: Robinson J. G. 
Published: February 2011

Abstract
By means of a new technique for the determination of volume resistivity, the effect of compounding variations in a basic mixing containing about 80 per cent volume of rubber was investigated, with the following outstanding results: (1) Above a certain limiting concentration, substitution of zinc oxide for French chalk gave decreased resistivity. (2) Resistivity increased progressively with increase of stearic acid concentration. (3) Of the three antioxidants examined, two had little effect on resistivity, one produced a decrease. (4) The six accelerators examined produced large differences in resistivity; thus, mercaptobenzothiazole gave values of the order of five times that of diphenylguanidine. (5) Increase in accelerator concentration gave decreased resistivity. (6) The variation of resistivity with time of cure depended on the compound under investigation. The usual behavior was an increase with increased curing time, followed in some cases by a decrease. This is the same type of behavior which is shown by tensile strength, but no general connection could be traced between the development of tensile strength and of resistivity.
The Heat Conductivity of Rubber at Low Temperatures
Authors: Schallamach Adolf 
Published: February 2011

Abstract
The experimental evidence points to the fact that a transition of some kind takes place at about 210° K, which, however, in consequence of supercooling, may take effect at a considerably lower temperature. As is mentioned in the Introduction, there is other evidence of such a transition. The thin curve in Figure 2, which is taken from the paper of Bekkedahl and Matheson, gives the specific heat of amorphous rubber. A sudden rise of this quantity occurs just below 200° K, and we feel sure that this near coincidence is more than accidental. The temperature lag between the two may be accounted for by the fact that Bekkedahl and Matheson worked with pure rubber hydrocarbon, whereas the material used for our investigation was vulcanized rubber. Bekkedahl's experiments on the temperature-volume relationship of various kinds of rubber showed that this transition is shifted towards higher temperatures when the rubber has been vulcanized.
Electrically Conducting Neoprene and Rubber
Authors: Habgood B. J. , Waring J. R. S. 
Published: February 2011

Abstract
(1) The scattered references in the literature dealing with conducting rubber have been collected together. (2) A résumé of existing ideas on the mechanism of electrical conduction is given, from which certain lines of development work suggested themselves. (3) Electrically conducting Neoprene or rubber compounds based on acetylene black are anisotropic, an effect which is particularly pronounced after extrusion. (4) By the use of fine channel black, either alone or in addition to acetylene black, the transverse conductivity is improved, thus reducing the anisotropy. (5) A further improvement can be obtained by using highly plasticized Neoprene or rubber which reduces the shear during extrusion operations. In the case of Neoprene, zinc oxide is omitted from the mixings to prevent set-up. (6) Conducting tubes having a transverse volume resistivity of 300 ohms per cu. cm., and a longitudinal resistivity of 60 to 70 ohms per cu. cm. have been obtained, using a potential difference of 6 volts. (7) Provisional methods of testing conducting rubber are suggested.
A Method for the Testing of Adhesive Tape
Authors: Geer William C. , Wescott W. Burton 
Published: February 2011

Abstract
The authors performed several thousand tests upon adhesives of different compositions, manufactured under excellent controlled factory conditions and carried upon backs of a variety of constructions. One conclusion was clear, which is included here even though this particular paper is devoted largely to a description of the test procedure alone. This is that other things being the same (paper or cloth of the same construction, methods of manufacture, and so on) each adhesive, when tested as described, gives a curve which is characteristic of its composition.
Fractionation and Molecular Weight of Rubber and Gutta-Percha
Authors: Kemp A. R. , Peters H. 
Published: February 2011

Abstract
1. Evaporated latex films and Bolivian fine para contain a chloroform-soluble fraction of about 62 per cent, whereas the soluble portion of crepe and smoked sheets is about 86 per cent. The average molecular weight of these sols, which contain the low polymers and “resin”, range from about 130,000 to 180,000, the more soluble type having the lower value. 2. Diffusion and precipitation methods were employed to fractionate R. C. M. A. crepe, and the following data indicate the approximate composition and molecular weight range of the soluble hydrocarbon fractions separated: 3. The chloroform-insoluble portion of crepe contains a nonlinear type of hydrocarbon, judged by x-ray and viscosity studies. These methods show that the chloroform-insoluble portion of ammonia-preserved latex films contain extremely high-molecular rubber hydrocarbon which is easily oriented to give the regular x-ray crystalline pattern for rubber. 4. Freshly tapped latex contains a large proportion of petroleum-ether-soluble fraction, which becomes insoluble in this solvent on standing in the presence of ammonia. Ammonia-preserved latex films are soluble in chloroform or in hexane containing alcohol-acetone or acetic acid; this insolubility is thus an association effect, which is overcome by the addition of a polar solvent. 5. Viscosity studies on fractions of balata and gutta-percha show that their hydrocarbons have an average molecular weight of about 42,000 and cover a narrow polymeric range.
The Molecular Weights of Rubber and Related Materials: I. Experimental Methods
Authors: Gee G. 
Published: February 2011

Abstract
The osmotic molecular weight of crepe has been measured in several solvents. It is shown that the use of a poor solvent, or a mixture of solvent and precipitant, gives solutions which approach ideal osmotic behavior. Benzene containing 150 cc. of methanol per liter is the best solvent examined, 1 per cent solutions of crepe being almost ideal. Viscosity data are employed to calculate absolute weight average molecular weights, the Staudinger constant being determined by comparison with ultracentrifuge data. Constants are listed for a number of solvents, and shown to vary only by a small factor. The osmotic and viscosity molecular weights of a number of rubbers are compared; the two values agree for three rubber fractions, while for unfractionated materials the viscosity average is the higher. Non-uniformity coefficients are calculated from the ratio of the two molecular weights. The molecular weight of sol rubber is higher than that of gel, showing that the sol-gel separation does not arise from molecular weight difference. The Staudinger law is shown to hold for rubber solutions at least over the molecular weight range 350,000–60,000, and probably very much further.
Viscosity-Molecular Weight of Rubber. Cryoscopic Deviation of Rubber Solutions from Raoult's Law
Authors: Kemp A. R. , Peters H. 
Published: February 2011

Abstract
1. The cryoscopic method is not satisfactory for polyprenes with chain lengths much greater than about 20 isoprene units on account of the failure of their solutions to obey Raoult's law. 2. Since Staudinger's viscosity-molecular weight constants were in many cases determined on nonideal solutions, this subject will be further investigated. 3. The present work has led to the selection of a Kcm value of 0.75 × 104, which is 25 per cent lower that the value chosen by Staudinger, who used higher polymers which do not behave ideally in solution. 4. The use of Staudinger's equation, M=ηsp/CKm, leads to large deviations with the variations in viscosity usually employed, and this deviation is largely avoided by employing the equation M=(log ηr/C)Kcm.
Oxidation of Unvulcanized Rubber in Light
Authors: Blake J. T. , Bruce P. L. 
Published: February 2011

Abstract
When unvulcanized rubber is exposed to light in the presence of air, it develops a tackiness which may proceed far enough to cause partial liquefaction of the rubber. The nature and intensity of the light is unimportant, although the rate is affected. The action is oxidation, and is accompanied in many cases by peroxide formation and a Russell effect. This production of tackiness under the influence of light is susceptible to the action of organic catalysts, both positive and negative. Many materials used regularly as antioxidants in vulcanized rubber are active agents in the development of tackiness. A number of other materials effectively retard the development of tackiness. In many cases they suppress completely the positive action of these commercial antioxidants. Antioxidants appear, therefore, capable of playing a dual role—that of assisting rubber oxidation under some circumstances and that of retarding oxidation under others. This paper describes a method and apparatus for the quantitative study of the rate of oxidation of raw rubber. In the previous paper the tackiness of the raw rubber was of necessity judged wholly by appearance and feeling. Although it increased with time of exposure to light, in many cases it decreased again after having reached a maximum. We assumed that this subsequent decrease in tackiness was due to additional oxidation, but there was no proof. There was also no evidence that the development of the same degree of tackiness in rubber containing different materials represented the same degree of oxidation.
The Isolation of Amino Acids from Rubber Latex
Authors: Whitby G. S. , Greenberg H. 
Published: February 2011

Abstract
The following amino acids are shown to occur in the serum of the latex of Hevea brasiliensis, all except the last having been actually isolated from it: tyrosine, l-leucine, d-iso-leucine, d-valine, d-arginine, l-aspartic acid, i-proline, and phenylalanine. A cursory examination of the amino-acid composition of the heat-coagulable protein of latex has been made. A tabular summary is given of the results obtained by various workers to date on the amino-acid composition of latex and latex proteins.
A Central Organization for Fundamental Research on Rubber
Authors: McPherson Archibald T. 
Published: February 2011

Abstract
Far-sighted leaders of the rubber industry have long recognized the need of more research on rubber, particularly research of a broad, fundamental character. Ambitious plans have been proposed from time to time for the sponsoring of such research by the rubber industry. The usual history of these plans is that they have been ably presented, discussed at length, and ultimately allowed to lapse. This paper, reviving the subject, is the outcome of a conversation with the forward-looking editor of India Rubber World, and is here presented at his suggestion in the hope that it may lead to new interest and ultimately to some tangible accomplishment. The present plan, which involves no essentially new or original features, is that a relatively small, but strong, central organization be created to undertake difficult, long-term, fundamental research on rubber and, at the same time, to promote research in universities and in industry by coöperation through the dissemination of information and by other means.
Comparison between the Observed Density of Crystalline Rubber and the Density Calculated from X-Ray Data
Authors: Smith W. Harold , Hanna Nancy P. 
Published: February 2011

Abstract
When unvulcanized rubber is stretched quickly, an orientation of structure occurs parallel to the direction of extension. This orientation is usually regarded as a form of crystallization, because of the optical and other phenomena which accompany it. It is also accompanied by a change of volume. When unstretched rubber is subjected to suitable temperatures below about 10° C, it too becomes crystalline. The crystallization of rubber is accompanied by an increase of density, and the simultaneous production of an x-ray diffraction pattern is usually interpreted as evidence that crystallization has occurred. A diffraction pattern of this kind results from regular repetition, within the crystal structure, of groups of atoms or molecules in a definite spatial arrangement. The smallest group from which the structure can be built up in this way is called the unit cell; and the dimensions can be computed from measurements of the pattern, provided it is possible to determine the crystal form. The pattern of stretched rubber consists of interference spots, and that of frozen rubber consists of rings, but both of their measurements have been shown to indicate the same unit cell. If, in addition, the number of atoms in the unit cell is known, the density of the material can be computed. If the computed density agrees with that found by direct measurement, the fact is a valuable indication of the correctness of the assumed structure on which the calculation of density was based. Accurate knowledge of the density of completely crystallized rubber would therefore serve both as a guide in studies of structure and as a measure of the degree of crystallization of any material under consideration. In the experimental work described in this paper, the rubber was crystallized as completely as possible. Its density was determined by recognized methods, and compared with the densities calculated from x-ray measurements.
The Viscosity of Preserved and Concentrated Latex. III. Relationship of Viscosity to Temperature and Dry-Rubber Content
Authors: Smith H. Fairfield 
Published: February 2011

Abstract
The purpose of this paper is to deduce, from data given by Rhodes on the viscosity of latices and of latex-water mixtures at different temperatures, mathematical formulas by which the observations may be succinctly described. These will serve as a convenient means for interpolation and for the deduction of quantitative estimates of the changes in the viscosity of latex with temperature and dry rubber content (d.r.c.); and may facilitate comparison with the variations in viscosity of other substances and with theories or hypotheses.
Trilinear Compounding
Authors: Forman D. B. 
Published: February 2011

Abstract
Trilinear compounding enables the factory compounder to select the particular rubber or synthetic rubber composition that will have the physical properties specified. It saves time in eliminating trial-and-error methods of compounding. Briefly, charts of this type actually tell the ratio of rubber (or synthetic rubber): filler: softener, and similar charts can be made to show other systems. Every rubber chemist knows that there are two primary methods of altering the physical properties of vulcanized rubber and synthetic rubber—chemical and physical. The former is controlled by antioxidants, accelerators, activators, and other curing agents; the latter is controlled by fillers and softeners. This discussion deals with the physical methods that are applicable after factors influencing rate and state of cure have been fixed. This method of compounding has been named “trilinear compounding”. It employs charts which show the effects of varying three ingredients in a compound. In other words, it deals with a compound as a unit which is divisible into three parts. Trilinear compounding is not new; it is used regularly in the paint and plastics industry. Undoubtedly, several rubber chemists have used it in connection with compounding by chemical means and in many special applications, but its recourse to fillers and softeners is believed to be new to most rubber chemists.
Determination of Zinc in Rubber Compounds. A New Internal Indicator Method
Authors: Tyler Willard P. 
Published: February 2011

Abstract
Two internal indicator volumetric methods for the determination of zinc in rubber compounds have been devised and investigated. The first method is a wet-oxidation method employing nitric acid, bromine, and perchloric acid as oxidants, and p-ethoxychrysoidine, a new oxidation-reduction indicator for this use, as indicator. It is of general application to all types of rubber compounds. The second method, less generally applicable to rubber compounds, utilizes either the new indicator or the well-known indicator, diphenylbenzidine. This method depends on ashing of the sample, and cannot be used for the analysis of zinc in rubber compounds containing lead or silicates, since it has been found that no method in which the sample is ashed yields accurate results if these substances are present. Both methods use potassium ferrocyanide as the volumetric precipitant and potassium ferricyanide as an integral part of the indicator system. Both methods are applicable to other organic and inorganic zinc-containing materials. The first method appears to have a slight advantage in ease of manipulation, total time of determination, and range of applicability. There is little choice between the methods or indicators as regards precision, accuracy, or the actual time used by the analyst for a determination, providing each method and indicator is used only under the proper conditions. Both methods are superior to the external indicator method using uranyl acetate, the method now in common use in rubber laboratories.
The Economics of the use of Neoprene Reclaim
Authors: Fraser Donald F. 
Published: February 2011

Abstract
It is possible to reclaim mould and other vulcanized Neoprene scrap by suitable reclaiming procedures. At the present time, most of the reclaim manufacturers are prepared to do this reclaiming on a custom basis. The Neoprene of the reclaim may replace as much as 50 per cent of raw Neoprene in a compound to reduce by as much as 25 per cent the volume cost, without greatly impairing the physical properties of medium-or low-grade mechanical goods vulcanizates. Use of Neoprene scrap in this manner will conserve the supply of Neoprene, and under present conditions the value of such conservation is obvious. Besides, this utilization of scrap will reduce the overall factory cost of many types of Neoprene products. Although the volume of Neoprene scrap available at the present time is small, the presence of larger amounts on the market, as a result of increased Neoprene production, must be anticipated. Because of increased interest in Neoprene reclaims, due attention should be given to the problem of classifying and standardizing types of Neoprene scrap and reclaim.
Vulcanizing of Ebonite. Controlled Curing of Natural and Synthetic Rubber Ebonites of Large Cross-Section
Authors: Quinn N. G. 
Published: February 2011

Abstract
The vulcanizing of ebonite, particularly of large blocks or bars of substantial cross-section, has long been a source of production difficulty. The tendency of such vulcanizates to develop porosity or even more serious gassing has always necessitated a prolonged curing period at a comparatively low temperature. Improved compounding technique has greatly accelerated the curing process, but the period is still excessive and production is impaired. The proposed method of control enables a higher curing temperature to be used, with a consequent considerable reduction in curing time; it further makes possible the use of stocks which previously could not be satisfactorily cured at all above a certain thickness.
Transparency of Rubber and Its Solutions
Authors: Stevens Henry P. 
Published: February 2011

Abstract
When rubber is dissolved in benzene or a mixture of coal-tar hydrocarbons, a clear bright solution is usually obtained. On the other hand, when dissolved in a petroleum solvent, the solution is opalescent. In the latter case it is necessary to postulate the presence of small particles having a different refractive index from that of the solvent. As rubber gives a substantially clear solution in benzene, it follows that the foreign particles are invisible and must, therefore, possess the same refractive index as this solvent or one very close to it.
Heat Generation in Flexed Rubber
Authors: Gehman S. D. , Jones P. J. , Woodford D. E. 
Published: February 2011

Abstract
The problem of heat generation in tires assumes new importance with the advent of synthetic rubber and the increased use of reclaimed rubber. Even if reduced speeds may prevent heat blowouts, higher temperatures mean that both fabric and rubber are operating under unfavorable conditions. Synthetic rubber, in particular, is then working at reduced tensile strength and tear resistance. It is more susceptible to heat embrittlement, cuts, and abrasion. A number of flexometers for rubber testing have been described, and some of these instruments have been widely used. The flexometer described here is characterized by simplicity of construction, high speed, and convenience of operation.