bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rubber Solvents and Substances Which Lower the Viscosity of Rubber Cements
Authors: Fabritziev B. V. , Buĭko G. N. , Pakhomova E. A. 
Published: February 2011

Abstract
1. The greatest effect in reducing the viscosity of rubber solutions is produced by alcohols. This effectiveness increases in the following order: isopropyl, butyl, ethyl propyl, isoamyl, and methyl alcohol. Of these the most active is methyl alcohol and the least active isopropyl alcohol; all other alcohols are closely similar in action. Acetophenol, pyridine, and acetone also reduce considerably the viscosity of rubber solutions, but are greatly inferior in their effectiveness to the alcohols. Ethyleneglycol and dichloroethane reduce the viscosity very little. The addition of 1 to 5 per cent of water greatly increases the viscosity, which contradicts the observations of Messenger and Porritt. However the concentration of water in our experiments was considerably higher than that used by these authors. 2. With higher concentrations of active liquids, the degree of reduction of viscosity increases, but there is a definite limit of concentration above which further reduction of viscosity is very small. With alcohols this limiting concentration is at 2–3 per cent. 3. The effect of active substances in the reduction of viscosity depends on the concentration of the cement and on the preliminary mechanical treatment of the rubber, i. e., the greater the concentration of cement and the less the rubber is subjected to preliminary mechanical treatment, the greater the reduction of the viscosity; in other words the higher the original viscosity the greater is the reduction in the viscosity by active substances. 4. The viscosity of a rubber cement increases during storage, regardless of the presence of an alcohol. During short periods of storage (up to 1 day) the effectiveness of time alcohol is maintained, but during prolonged storage its action decreases and with methyl alcohol the viscosity actually increases. 5. The rate of gelation of a self-curing cement depends on the nature of the viscosity-reducing agent. Methyl alcohol causes more rapid gelation than ethyl alcohol. In conclusion, for reducing the viscosity of self-curing cements the addition of 3 parts of ethyl alcohol to 100 parts by weight of a cement it is recommended as the lest procedure for industrial requirements.
The Effect of Addition of Colloids on the Coagulation of Latex
Authors: Tanaka Yoshio , Kuwata Tsutomu , Noguchi Takashi 
Published: February 2011

Abstract
1. A known proportion of colloid was added to dilute, dialyzed latex (rubber content 3.5 per cent) to determine the effect of colloids on the coagulation of latex. Various proportions of 0.2 N acids were added; the mixtures were then left for 24 hours. The relations between the state of coagulation of latex and the proportion of acid are shown graphically. 2. The coagulation curves of acetic, hydrochloric, sulfuric, and nitric acids show that latex is coagulated by a definite quantity of acid, above which proportion the coagulation disappears and then reappears by further addition of acid. The first coagulation is apparently governed by the p H value of the dispersed medium, and the charge on the surface of the rubber particles is opposite to that of rubber dispersed in an alkaline medium. The second coagulation is governed by the concentration of cations. 3. Gum arabic, casein, saponin, gum tragacanth, glue, “funori,” or hemoglobin were added to latex and coagulation obtained by the addition of 0.2 N acetic acid or hydrochloric acid. Each gave the characteristic curve of a protective colloid; dextrin, however, had no influence on the coagulation curve. 4. The influence of the colloids on the coagulation curve is of particular interest in studying further the properties of colloids and rubber particles, and this will be discussed in detail in connection with further investigations.
Effect of Pressure on the Dielectric Constant, Power Factor, and Conductivity of Rubber-Sulfur Compounds
Authors: Scott Arnold H. 
Published: February 2011

Abstract
This paper reports the results of a study on the effect of pressure on the dielectric constant, power factor, and conductivity of rubber-sulfur compounds, and is the third paper of a series dealing with the electrical properties of rubber-sulfur compounds. The previous papers dealt with the effect of sulfur content, temperature, and current frequency on these electrical properties. The results reported in the present paper have been corrected for changes in the dimensions of specimens caused by changes in pressure. The required data for making these corrections were obtained from a detailed study of the compressibility of rubber-sulfur compounds which has recently been completed.
Semi-Ebonite. Part 2
Authors: Gibbons P. A. , Cotton F. H. 
Published: February 2011

Abstract
In Part 1 (Rubber Chem. and Tech., 8, 554 (1935)) frequent reference was made to the volatile products emitted during the aging of semi-ebonite under different conditions. In this section an experiment is described wherein the various products were detected and some attempt made to estimate the relative amounts of each. The experiment in its original form presented considerable difficulty, and many disappointments were experienced before a modified apparatus was finally adopted. Experimental Method.—Eight test-pieces, one from each of the accelerated cures (see Part 1), were cut to a convenient size, six inches by one inch. The test-pieces were carefully weighed and their thickness determined as the average of several readings on the micrometer. The strips were suspended from a bent glass rod projecting from a cork-bearing inlet and outlet tubes (see Fig. 5). The cork was then inserted in a clean conical flask and the latter sealed with wax until it withstood a considerable vacuum. The flask was placed in a Geer oven automatically maintained at 70° C. The outlet tube was attached to an absorption train and the inlet tube to a purifying train.
Determination of Free Sulfur in Rubber Containing Mercaptobenzothiazole and Tetramethylthiuram Disulfide
Authors: Kheraskova E. , Korsunskaya E. 
Published: February 2011

Abstract
Free sulfur in a given vulcanizate is a definite and constant quantity. It can be extracted from rubber with acetone and various other sulfur solvents, and can be reduced directly in the rubber to hydrogen sulfide. The claim of Teny, supported by experimental evidence, that acetone extracts the entire sulfur in rubber has not been confirmed by other investigators. Several methods for the determination of free sulfur in rubber are known. The classic method, adopted by the U. S. National Bureau of Standards, involves the extraction of sulfur with acetone and subsequent oxidation of the sulfur with bromine to sulfuric acid. The extraction consumes from 4 to 6 hours. This method gives excellent results with rubber mixtures containing no sulfur-bearing accelerators. When sulfur-bearing accelerators are present in a rubber mixture, they are dissolved by acetone and may be oxidized together with the extracted sulfur by bromine. To investigate the possible effect of accelerators (mercaptobenzothiazole and tetramethylthiuram disulfide) in a rubber mixture on the determination of free sulfur by the classic method, a series of experiments on the determination of sulfur in these accelerators under the conditions of analysis of free sulfur was undertaken.
Sulfuric Acid as a Latex Coagulant
Authors: Wiltshire J. L. 
Published: February 2011

Abstract
The replacement of formic or acetic acid by sulfuric acid for coagulating has the obvious attraction of saving money, but this acid undoubtedly has a bad reputation among planters, and the published literature on the subject is not encouraging. Several authors of standard books on estate practice have emphasized the results of Martin, who observed that the addition of one-eighth of one per cent of sulfuric acid to dry rubber caused a very marked retarding effect on the rate of vulcanization. As, however, the total amount of acid used for coagulation is approximately one-half of one per cent, and by far the greatest proportion of this will be removed in the serum and in the wash-water, it seems unlikely that any quantity approaching Martin's figure would be allowed to remain in the rubber. Martin's results can be regarded as nothing more than a warning, and certainly do not constitute any real evidence of the unsuitability of sulfuric acid.
Studies on the Nature of the Action of Organic Accelerators for Rubber Vulcanization. IV. The Detection and Analysis of Organic Accelerators. Systematic Identification of Organic Accelerators
Authors: Shimada Keiichi 
Published: February 2011

Abstract
Though much work has been carried out and recorded on the comparative vulcanizing power of various organic accelerators, yet so far as the author is aware, there is very little published work on the detection of commercial organic accelerators; probably a few laboratories have some special test of their own, but as yet no one has seriously taken up this field. The present investigation was carried out with a view to devise a simple but satisfactory systematic method of identifying general organic accelerators now used in the rubber industry.
The Determination of Free Sulfur by a Volumetric Method Part II
Authors: Guppy W. D. 
Published: February 2011

Abstract
1. The method previously described for the volumetric determination of free sulfur in vulcanized rubber has been compared with the older gravimetric methods in cases where other organic compounds containing sulfur are present in the vulcanizate. 2. The volumetric method gave lower results than the methods involving oxidation of the acetone extract in the case of vulcanized rubber containing aldehydeamine condensation products of thiouram disulfide compounds. This indicated that the sulfur combined with some organic compounds was not reduced by the reagents used. 3. The results with the accelerator tetraethylthiouram disulfide showed that in some cases part of the sulfur in organic compounds was reduced under the conditions of the reaction. 4. The acetone-soluble and the acetone-insoluble portions of brown substitute contain organic sulfur compounds. Part of the sulfur in these compounds was reduced to hydrogen sulfide by the action of nascent hydrogen. 5. The sulfur compounds present in white substitute were stable toward the reducing agents used in the estimation of free sulfur. 6. The sulfur compounds formed by the vulcanization of ebonite were in part reduced to hydrogen sulfide with tin and acid. Variations in the composition of the mixing and in the vulcanizing conditions altered the amount of these reducible compounds. 7. The volumetric method previously described cannot be used for the determination of the free sulfur in ebonite, brown substitute or in vulcanized rubber containing brown substitute. In the case of vulcanized rubber containing brown substitute or of ebonite the method can be used to determine the amount of sulfur in the acetone extract. 8. The volumetric method can be employed for the determination of the free sulfur in soft vulcanized rubber containing white substitute and in reclaimed rubber.
The T-50 Test for State of Cure
Authors: Gibbons W. A. , Gerke R. H. , Tingey H. C. 
Published: February 2011

Abstract
In tires, machine supports, conveyor bells, hose, waterproof clothing and footwear, and other rubber articles, the state of vulcanization of the rubber in the rubber compound is important for best results in service. A simple, rapid, and accurate physical test for state of cure is described, which is independent of the composition of the rubber compound. The test depends upon the observation that for a specific rubber compound the greater the state of cure the lower is the temperature at which chilled stretched rubber will spontaneously retract.
Anode Process for Rubber Articles and Coatings
Authors: Beal C. L. 
Published: February 2011

Abstract
THE term “anode process” has been chosen and used widely in the trade to designate a fundamental method for the production, directly from rubber latex, rapidly, and in one application, of articles and coatings of the highest grade of unmasticated rubber. Rubber latex, a milky exudation from the bark of rubber trees, is composed chiefly of tiny particles of rubber suspended in a water phase or serum, not unlike globules of butter fat in milk. Rubber latex contains small amounts of many organic compounds and inorganic salts. Some of these non-rubber materials, such as the proteins and resins, are considered to be adsorbed on the surfaces of the rubber particles and to be responsible for many of the colloidal characteristics of latex. As it comes from the tree, the latex is unstable and coagulates easily, but, when stabilized with ammonia, it can be safely shipped and stored for long periods. Like most colloidal particles in suspension in an alkaline medium, the rubber particles of ammoniated latex are negatively charged through the adsorption of hydroxyl anions. The particles, many as small as 1/25,000 inch in diameter, are in constant oscillation (Brownian movement) and are kept from hitting one another and sticking together (coagulating) by the repulsion of their electric charges. When the hydroxyl ions are neutralized or otherwise removed from the particles, the electric repulsion between particles disappears and coagulation results.
Tensile Tests of Vulcanized Rubber at High Speed
Authors: van Rossem A. , Beverdam H. B. 
Published: February 2011

Abstract
The types of apparatus most frequently used for elongation tests of rubber have only a slow speed. Thus the maximum rate of elongation of the Schopper dynamometer is 120 cm. per minute and in ordinary practice 60 cm. per minute is the speed used. The normal rate ordinarily used in America with the Scott apparatus is 20 in. per minute. On the other hand, it has been found by experience that slightly vulcanized rubber which, on the Schopper machine, gives very good values of tensile strength and resilient energy at rupture, even excellent values, is on the contrary brittle when stretched very rapidly by hand and breaks with a very low elongation. Consequently it is of interest, chiefly from the point of view of a study of rubber, to carry out elongation tests at high speed. As is easily seen from the technical literature, this problem has been neglected. At the Bureau of Standards the influence of the rate of elongation on the results of tensile tests has already been studied, but the rate varied only between five and forty-five inches per minute. Briefly, the results of this study seem to indicate a general tendency for the elongation and resistance to extension to increase with increase in speed of elongation. Hauser and Rosbaud have also made tests on the influence of the speed of elongation, but their tests were on raw rubber and at extremely slow speeds. As for the brittleness which appears at high rates of elongation, only very casual references are to be found in the literature. By a study of gas black Park has proved that the maximum physical properties found by hand-testing do not agree with the maximum obtained with the Scott dynamometer. Recently Wright5 has also pointed out the “shortness” of vulcanized rubber and has emphasized the importance of tensile tests at high speed. Unfortunately, we did not have at our disposal any apparatus which permitted recording the stress-strain curve at high speed and reading the ultimate elongation and tensile strength. Accordingly, we used in our tests a Charpy ram pendulum, belonging to the section of metallography of the Polytechnical School of Delft. It is known that this apparatus as well as others similar to it are used in determining the energy necessary to rupture various materials. This apparatus was changed and on the two supporting surfaces were attached two pins in such a way that a rubber ring could be placed there without elongation as seen in Fig. 1. This ring was then broken with the ram pendulum. The greater the energy expended in breaking the ring, the less the pendulum rises. As is known, the energy expended in breaking the ring is calculated by the aid of a numerical table by comparison with an oscillation without rupture of the ring. For each type of vulcanizate, at least six rings were tested by this pendulum method. In addition some rings from the same vulcanizates were given the usual tensile test on the Schopper dynamometer. From the resulting curve the energy of rupture can be determined in kilograms in the usual manner by the aid of a planimeter.
The Kinetics of the Vulcanization of Rubber
Authors: Nordlander Birger W. 
Published: February 2011

Abstract
While engaged in the development of a sensitive test for mercury vapor, the writer made the observation that if sulfur were melted and then allowed to cool, a surface was formed that at first was very reactive to mercury vapor, as evidenced by the rapid formation of black mercuric sulfide. However, a day or so after preparation, the surface had lost its reactivity entirely, since even exposure to mercury vapor of high concentration at an elevated temperature failed to produce any blackening at all. It appeared as though an active but unstable form of sulfur had been produced when the sulfur was melted, which in short time had changed over into a non-reactive form. This curious behavior of sulfur seemed interesting enough to warrant a separate investigation, and a study was, therefore, made of the activity of various forms of sulfur toward mercury vapor, the details of which will be published in a separate paper. However, before stating the results that were obtained, a brief review of our present knowledge of the various allotropic modifications of sulfur will be included. The most common form of sulfur is the rhombic, or Sα, modification which is stable up to 95° C. At this temperature it changes over into the monoclinic, or Sβ, form, which is stable in the region between 95° C. and the melting point, 114.5° C. When melted, the sulfur forms a pale yellow fluid liquid which, when heated further, goes over into a brownish, very viscous state with a maximum of viscosity at 160°–170° C. Above this temperature the melt becomes more and more fluid and boils at 444.5° C. From the classical work by Smith and co-workers it is known that there are two forms of sulfur in the melt, called Sλ and Sμ, the former of which is soluble in CS2, and on freezing out yields the two crystalline forms of sulfur. The latter is insoluble in CS2, is amorphous, and will, on rapid freezing out, retain the amorphous state which, however, at room temperature gradually is converted into Sα, especially in the presence of crystalline sulfur. The amount of Sμ present in the liquid at the melting point is very small, but increases rapidly with the temperature, especially around 160°–170° C., causing the highly viscous state of sulfur at these temperatures.
Isoprene and Rubber. Part 23. Cryoscopic Measurements of Rubber Solutions
Authors: Staudinger H. , Bondy H. F. 
Published: February 2011

Abstract
Pummerer, Andriessen, and Gündel published a work with this title which contains a number of remarks about the communication of Staudinger, Asano, Bondy, and Signer. The following discussion deals with this subject. 1. Molecular Weight Determinations of Rubber in Camphor according to East Determinations of the molecular weight of rubber in camphor cannot explain the constitution of rubber because, as has been explained before, when rubber is heated in melted camphor, at 170°-180°, a very pronounced decomposition of the rubber to semi-colloidal cleavage products takes place. The rubber molecule is very unstable as a consequence of the peculiar position of the double bonds in the chain; cleavage takes place with extraordinary ease, and attention has already been called to the fact that the cleavage of hexaphenylethane into triphenylmethyl, of dicyclopentadiene into cyclopentadiene, as well as the migration of the ally group, e. g., in phenylallyl ethers, the mobility of the substituents in allyl residues and finally the extremely easy depolymerization of rubber, all have one and the same cause: namely, that a substituent in the ally! group is very loosely combined. These facts, which are of such importance in the chemistry of rubber, should not be ignored as happens in most works on rubber. In order to study the decomposition, we carried out viscosity determinations. As the following experiments show, the viscosity of rubber is much less after melting in camphor than before. There occurred a very great decomposition at 170°, as was to be expected, and the relation t1/t2 which characterizes the decomposition is about 15. If pure rubber is decomposed in boiling tetralin the relation t1/t2 = 6.2. The decomposition in camphor is, therefore, surprisingly great, possibly because of the greater concentration of the dissolved rubber. The camphor solution used was 10 per cent, that of tetralin on the contrary was only 1 per cent.
The Long Spacings of Rubber and Cellulose
Authors: Clark George L. , Corrigan Kenneth E. 
Published: February 2011

Abstract
1. A new method for the examination of highly polymerized compounds is proposed. This consists in the direct measurement from diffraction interferences of colloidal micelle dimensions. 2. The construction of an instrument consisting of an x-ray tube with magnesium target and vacuum camera without intervening window or air space is described. 3. The major spacing of unstretched vulcanized rubber is found to be 99.3 A˚. U. 4. The number of isoprene molecules per unit cell is estimated to be of the order of eight thousand. 5. Three measurements of the long spacings of cellulose are recorded.
The Action of Solvents with Rubber
Authors: Stamberger P. , Blow C. M. 
Published: February 2011

Abstract
1. Methods and results of measurements of the swelling pressure and osmotic pressure of rubber jellies and solutions are described. 2. Within the range of concentrations which was measured, no differences were found between the rubber jellies and the solutions. 3. Rubber of various origins gave the same values. 4. A few influences which bring about changes in viscosity have been discussed.
The Oxidation of Rubber at Atmospheric Temperatures
Authors: Davey W. C. 
Published: February 2011

Abstract
(1) Oxidation at ordinary temperatures in the dark proceeds very slowly for unextracted rubbers, but at quite a reasonable speed for extracted rubber-sulfur mixings. The rate of oxidation of accelerated mixings, even if acetone-extracted, is very slow. (2) The final increases in weight after long aging are higher at ordinary temperatures than at 70° C. and the amount of acetone extract and the (acetone extract)/(increase in weight) ratios are also very much higher. (3) Storage in a moist atmosphere retards the oxidation in comparison with storage in a dry atmosphere, but the relative rates of oxidation in the two media are dependent on the rubbers under consideration. With slowly oxidizing samples, the lower the degree of cure the less the difference in oxidation rates, but with fast oxidizing rubbers the difference in rates of oxidation in the two media is less if the degree of cure is higher. The amount of acetone extract formed is less during storage in a moist atmosphere than in a dry one. (4) The acetone extract curves show definite maxima due to the change of the extract to insoluble matter, but the tendency for this change is small at atmospheric temperatures. (5) The effect of exposure in sunlight is to cause markedly lower acetone extracts to be obtained than when the samples are stored indoors. Exposed in quartz tubes, the extent of the acetone extract change to insoluble matter is of the order of that at 70° in the dark, and the acetone extract curves are of a similar form. Exposed in glass vessels the degree of extract conversion is not so great as at 70° but very much greater than when the samples are stored indoors. Accelerated mixings exposed in sunlight give very high acetone extracts, indicating that the acetone extracts of such mixings have little tendency to pass into an insoluble form.