bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Carbon Black on the Development of Oxidation Processes in Raw and Vulcanized Rubbers
Authors: Kuzmixskiĭ A. S. , Lyubchanskaya L. I. , Khitrova N. G. , Bass S. I. 
Published: February 2011

Abstract
Publications by Rebinder, Ab, and Vei˘ler, Pisarenko and Rebinder, and Dogadkin, Pechkovskaya, and Chernikina have been devoted to an explanation of the mechanism of the accelerating action of carbon blacks. However, only fragmentary and contradictory information about the influence of carbon blacks on the development of oxidation processes is found in scientific literature. In the present article, several important laws regarding the role of channel carbon black in the oxidation of sodium-butadiene rubber are studied. Carbon black can be incorporated in rubber in high proportions (100–125 parts by weight to 100 parts of rubber). It is well known how great is the influence of the surface area of reaction vessels in which the rupture of chains takes place on the development of chain reactions. It is also known that the oxidation of any type of rubber is a chain process of decomposition, with formation of side chains. Therefore in the study of these processes in rubbers, it is necessary to take into account the highly developed surface of contact between the carbon black and rubber particles.
Creep, Recovery, and Permanent Set for GR-S and Hevea
Authors: Gehman S. D. 
Published: February 2011

Abstract
A study was made of creep, recovery, and permanent set of Hevea and GR-S over a 1000-hour period and a range of elongations at 35° C. Creep of GR-S is greater than that of Hevea. The stress of GR-S is considered to be supported to a greater extent by a relatively unstable secondary bond structure. This is consistent with the large creep values of GR-S at low elongations and the large ratio of primary or recoverable creep to permanent set. Hevea, in contrast, shows low creep at both high and low elongations and maximum creep at intermediate elongations for which the structure is heterogeneous, consisting of amorphous and crystalline phases. A procedure was worked out for determining the contribution of permanent set to the observed creep. The creep curves were concave to the strain axis when plotted against logarithmic time. After correction was made for permanent set, they were found to be approximately linear, thus extending the range of application of the Tobolsky-Eyring theory of creep. At the start of the creep test the flow appears to be due largely to the reversible yielding of relatively weak bonds which can reform under the action of the elastic network when the stress is removed. For longer periods of time, or for higher elongations, the flow involves more deep seated changes in structure. Larger units of structure are displaced or stronger bonds broken with resultant permanent molecular displacements upon removal of the stress. For Hevea at high elongations all of the flow was accounted for by permanent set.
Factors Influencing the Configuration of Carbon Particles in Rubber
Authors: Parkinson D. , Blanchard A. F. 
Published: February 2011

Abstract
The properties of rubber vulcanizates containing channel black can be modified either by heat treatment under certain conditions of the rubber-carbon stock or by addition to the stock of small quantities of certain chemical substances, including benzidine. The effects of heat treatment and benzidine are to some extent additive, and it is shown by electrical resistance measurements that they are associated with changes in the configuration of the carbon particles in the rubber. The resistivity of unvulcanized channel black-rubber stocks depends on the temperature and on any temporary stretching or flexing to which the rubber may have been subjected. Any change which causes increased carbon structure which may occur when the stock is heated is reversed when it is cooled and strained. Remilling of rubber-black stocks results in an increased electrical resistance, due to a breaking down (decatenation) of chains of carbon particles. This effect is enhanced by previous heating of the stock or by incorporation of benzidine. Once the structure is broken down in this way there is no evidence that it can be formed again. For these and other reasons the hypothesis that individual carbon particles flocculate in rubber by a mechanism such as Brownian movement of the particles is rejected. It is suggested that the increased resilience of carbon-rubber vulcanizates following heat or benzidine treatment of the unvulcanized stock results from an increase of the carbon-rubber attachments at the expense of the carbon-carbon attachments.
Study of the Reaction of Buna Rubbers with Aliphatic Thiols
Authors: Serniuk G. E. , Banes F. W. , Swaney M. W. 
Published: February 2011

Abstract
Thioglycolic acid added exothermally to butadiene polymers and copolymers in benzene solution under mild conditions to give apparent double-bond saturation values of 38 to 47 per cent. When the same polymers reacted with aliphatic thiols of C2 to C16 chain length, in mass or latex reactions, saturation values were obtained which were in accord with those found by thioglycolic acid addition. It is suggested that the double bonds in butadiene polymers and copolymers which were readily saturated by the above thiols are predominately those present in the polymer chains as vinyl side groups.
Steam and Radio-Frequency Curing of Natural Rubber
Authors: Sharbaugh A. H. 
Published: February 2011

Abstract
The object of this investigation was to compare the resulting vulcanizates when natural rubber is cured in a conventional steam-heated mold and when it is cured by dielectric losses at radio frequencies under identical time-temperature conditions. In practice it is of course recognized that dielectric heating offers many advantages in speeding up heating processes through its inherent ability to heat uniformly throughout the mass, compared with relatively slower heating where heat is conducted in from hot surfaces. The purpose was, then, to determine if any appreciable difference in vulcanizates is obtained when identical conditions of time and temperature are artificially maintained by the two methods. One series of tests was made on samples with different curing times at a fixed curing temperature; another series was carried out with a fixed curing time, with the temperature the independent variable. Finally a comparison was made with samples which had a curing cycle consisting of a gradually rising temperature during a relatively short curing time—that is, the type of temperature variation normally encountered in a radio-frequency cure when a constant radio-frequency field is imposed on a rubber load. The vulcanizates were evaluated physically by measuring their stress-strain relationships and ultimate tensile properties, electrically by their dielectric constant and loss factor-frequency dependence, and chemically by the amount of sulfur of vulcanization. No significant differences were observed in the rubber products cured by the two methods.
Reclaiming Agents for Synthetic Rubber
Authors: Cook W. S. , Albert H. E. , Kilbourne F. L. , Smith G. E. P. 
Published: February 2011

Abstract
Some highly alkylated phenol sulfides have proved to be among the most active reclaiming agents for GR-S and other synthetic rubbers. A study has been made of the activities of these materials as related to molecular structure and to the fate of sulfur during the reclaiming process. The nature and mechanism of the chemical reactions taking place during the reclaiming of natural and synthetic rubbers have been discussed in the light of the results obtained.
Polymeric Unsaturation and Relative Rate of Cross-Linkage
Authors: Zapp R. L. 
Published: February 2011

Abstract
In conventional vulcanization reactions with sulfur and accelerator, the rate as well as the extent of cross-linking to form polymer networks depends on the concentration of chemical unsaturation. The purpose of this paper was to determine the relationships between polymeric unsaturation and the rate of vulcanization. The course of the cross-linking reaction was followed by volume swelling measurements converted to a relative cross-linked index; this index is shown to be directly related to extension modulus before the onset of crystallization. Experimental evidence with a system of polymer, zinc oxide, sulfur, and tetramethylthiuram disulfide closely approaches the hypothesis, based on the possible paths of cross-linkage between adjacent chains. The experimental equation, at constant relative cross-links of 18.2 at 1000 per cent volume increase in cyclohexane, is t=c/n1.8 when adjustments are applied. When a system utilizing benzothiazyl monocyclohexyl sulfenamide is studied, the time to a constant state of vulcanization is related to the reciprocal of the first power of the unsaturation, t=c/n. In both relations, t is time, n is the polymeric unsaturation, and c is a constant which depends on the temperature and state of cure. The difference in response to polymeric unsaturation by these two types of accelerators is reflected in the percentage of combined sulfur for a given concentration of cross-links (state of cure). The thiuram requires less combined sulfur for a given state of vulcanization than does the thiazole, whereas a nonaccelerated mixture requires still more combined sulfur for a given state of cure. In an attempt to rationalize the differences in accelerator behavior, four points are discussed which involve the concepts of active centers, carbon-carbon linkages, varying porportions of sulfur in a carbon-sulfur-carbon bridge, and consideration of inter- and intramolecular linkages.
Semiebonites
Authors: Rostler Fritz S. 
Published: February 2011

Abstract
To summarize the principal results of the present investigation, it was found that whereas natural rubber is a poor raw material for the manufacture of semiebonite, butadiene-styrene and butadiene-acrylonitrile rubbers are suitable raw materials, especially in combination with unsaturated hydrocarbon extenders of the Naftolen type. The superiority of GR-S to natural rubber in the form of semiebonite should be an interesting piece of information for every compounder conscientious about the importance of keeping up the use and the manufacture of GR-S. With natural rubber becoming more and more available, there exists, as we all know, the definite danger that GR-S will be pushed into the background. As a matter of fact, we are approaching the situation where the supply of rubber hydrocarbons, natural and synthetic, will exceed the demand by multiples if new uses for rubber in large volume are not found. The increased use of rubber products in the building and construction industry and in road surfacing might provide such an outlet for rubber. Semiebonite with good aging qualities might find many uses along these lines. It might lend itself to the manufacture of floor coverings, of waterproof wall insulation, etc. The possibilities of using semiebonites from GR-S for tire beads has been suggested in a previously published article, but no detailed study comparing various rubbers has been reported. The primary purpose of this report is to present these basic data, which can be used as starting points for compound development and to point out that we have in the semiebonite range a possibility of using GR-S to advantage. As to butadiene-acrylonitrile rubbers, with which, in distinction to GR-S, very useful semihard rubber products can be made with phenolic resins, the medium sulfur range opens the possibility of making semiebonites which are easier to process and cheaper than resin combinations. The use of plastics in the rubber industry was recently discussed and summarized by Winkelmann. The compounding of semiebonites with Naftolen-type products offers a means of regulating the plasticity of the uncured stock as well as the elongation of the vulcanizate. Aging and prevention of sulfur bloom appear also improved. In other words, it was found that the combined use of 15 to 20 parts of sulfur with 15 to 50 parts of a Naftolen-type hydrocarbon gives a satisfactory semiebonite with GR-S, as well as with Hycar, and both these rubbers appear superior to natural rubber in semiebonites.
Sulfur Linkage in Vulcanized Rubber. Reaction of Methyl Iodide with Sulfur Compounds
Authors: Selker M. L. 
Published: February 2011

Abstract
The work described here is an extension of the study of the reaction of methyl iodide with sulfur compounds originally begun with the purpose of using such data in determining the sulfur linkage in vulcanized rubber. A previous paper dealt with the reactions of methyl iodide with propanethiol, propyl sulfide, propyl disulfide, allyl sulfide, and thiophene. This article adds to the list, n-butyl methallyl sulfide, allyl disulfide, allyl tetrasulfide, n-propyl tetrasulfide, and trithiane. The removal of combined sulfur from vulcanized rubber as trimethylsulfonium iodide on treatment with methyl iodide at room temperature was persuasive evidence of the presence of sulfide sulfur linked to allylic type residues. The evidence offered, however, did not constitute exclusive proof because it was not known whether still other types of sulfur linkage would also yield trimethylsulfonium iodide. To shed more light on this question, the sulfur linkages most likely to occur in vulcanizates—the allyl-alkyl monosulfide, diallyl and dialkyl di- and polysulfide—were investigated. The trithiane reaction is of interest mostly from the point of view of the reaction of overcured stocks or secondary reaction products stemming from the original polysulfides. The reactions were carried out using the method described in a previous paper.
Strain Tester for Rubber
Authors: Holt W. L. , Knox E. O. , Roth F. L. 
Published: February 2011

Abstract
A tester for measuring the strain of rubber vulcanizates when subjected to a predetermined stress is described. The operation of the tester and a description of the apparatus for cutting and measuring the test specimens are presented. With this equipment routine determinations of a point on the stress-strain curve can be made with greater accuracy and precision than has hitherto been possible with the usual stress-strain equipment. This strain test also requires less labor than the customary stress tests.
Preparation of Dried Latex Films
Authors: Maron Samuel H. , Madow Benjamin 
Published: February 2011

Abstract
Various technical applications of latex call for the formation of a latex film and its drying by evaporation of the water in which the rubber is dispersed. The same problem is encountered also in the preparation of dried latex films, both uncompounded and compounded, for film testing for tensile, elongation, and other properties. Very frequently the preparation of such films is complicated by the development of surface cracks and ridges in the drying films, which mar the appearance of the films, detract from their strength, and make testing difficult and uncertain. These imperfections in the films generally arise from the formation of impervious surface skins on the drying latex. Such impervious skins lead to shrinkage and subsequent cracking of the films on the one hand, and to bubble formation on the other. The result is that the preparation of dried latex films by this method becomes a very slow process, which yields as a rule films of inferior appearance and quality. It was found in this laboratory that many of the difficulties encountered in the preparation of latex films by evaporation can be overcome by appropriate control of humidity in the initial drying stages, and the use of an agent which prevents formation of the impervious surface skins on the drying latex. The agent found to be most suitable with alkaline latexes for the latter purpose is carbon dioxide gas. By utilizing moisture and carbon dioxide in a definite technique, films can be prepared from various latexes which are smooth and uniform in thickness and possess improved appearance and properties. The purpose of this paper is to describe the technique developed for preparation of dried latex films by casting, and to give some results for tensile and elongation obtained on GR-S, Hycar, Neoprene, and natural latexes.
Properties of Ebonite. XXVIII. Influence of Light-Absorbent Pigments on Electrical Surface Deterioration during Exposure to Light
Authors: Fisher D. G. , Scott J. R. 
Published: February 2011

Abstract
The incorporation of gas black, ferric oxide, and lead titanate, which absorb actinic rays, into rubber-sulfur ebonites did not reduce the rate of electrical surface deterioration appreciably. It increased the final equilibrium resistivity, but not sufficiently for the increase to be of much practical value. This result confirms the conclusion from a study of the mechanism of surface deterioration that a light-absorbent pigment is unlikely to be effective in retarding deterioration because its particles are relatively large and far apart in comparison with the thickness of the surface layer responsible for the deterioration. The use of the mercury-vapor lamp causes a more rapid deterioration than daylight, but does not appear to alter the order in which the samples range themselves.
Properties of Ebonite. XXIX. The Absorption Spectrum of Ebonite
Authors: Dock E. H. , Porritt B. D. , Willott W. H. 
Published: February 2011

Abstract
The absorption spectrum of ebonite has some practical interest, because the absorption of light causes the surface to deteriorate. A knowledge of the absorption spectrum should help in discovering which are the harmful rays. Published information hitherto appears to be limited to radiation of long wave length, i.e., thermal or infrared. The present note describes experiments on rubber-sulfur (65:35 or 68:32) compositions vulcanized for about 5 hours at 155° C. Owing to the great opacity of ebonite, it is necessary to work with very thin specimens. Various methods of obtaining these suggest themselves: (1) grinding down a small thin sheet; (2) cutting thin shavings; (3) vulcanizing as of a thin film between glass or quartz plates; (4) vulcanizing a film of rubber, deposited on glass or quartz, by immersion in molten sulfur; (5) vulcanizing a deposited film of a rubber-sulfur mix by heating in an inert gas. Methods (1), (2) and (5) have so far been found the most satisfactory. In method (2) it is advantageous to soften the material by swelling, e.g., in nitrobenzene; the swelling liquid can then be removed by extraction with a volatile solvent. Methods (1) and (2) have the advantage of enabling specimens to be obtained from larger pieces that can be analyzed or submitted to other tests.
Behavior of Rayon Tire Cord during Latex Dipping
Authors: Gillman H. H. , Thoman Ray 
Published: February 2011

Abstract
A study of the behavior of two types of rayon tire cord during latex dipping was made with a laboratory treating unit. Results of the tests showed certain facts. The concentration of the latex bath increased as rayon tire cord was dipped. No change occurred in dipping cotton. Based on the weight of cord dipped, sulfonated oil cord caused a higher increase in bath concentration than waxy ester cord; based on the weight of latex consumed, the order was reversed. Waxy ester cord had relatively slow wetting-out characteristics compared to sulfonated oil cord; compared to both, cotton is infinitely slow. The ratio of water-to-solids pickup with both cords is identical for all concentrations of the bath examined. Because of this characteristic both cords behave identically in the bath provided the squeeze rolls are adjusted to give equal solids pickup. Ratio of water-to-solids pickup decreases as the concentration of the bath increases. Stable fibers, both cotton and rayon, need no adhesive treatment for satisfactory bonding to rubber. In contrast, continuous filament rayon cannot be used until it is treated. Adhesion is a function of solids pickup. Sulfonated oil cord picks up two to four times as much solids as waxy ester cord under a variety of conditions because of better wetting-out properties. By changing either the squeeze-roll pressure or the bath concentration solids pickup is changed. Cord produced from staple rayon picks up more solids than continuous filament cord because of protruding fiber ends. An increase in concentration of the latex bath causes an increase in solids pickup. Viscosity acts similarly. Particle size has no appreciable effect on solids pickup. Surface tension does not affect solids pickup by waxy ester cord; it does affect sulfonated oil cord to a minor degree at or below 46 dynes per cm. An increase in cord tension through the latex bath decreases solids pickup. As the speed of processing is increased, solids pickup increases. A wiping action on the dipped cord decreases solids pickup. No relation between contact time and solids pickup could be established.
Determination of Resistance to Abrasive Wear. IX. Influence of Grain in Tire Tread Rubber
Authors: Scott J. R. 
Published: February 2011

Abstract
Results of the Akron-Croydon abrasion test on rubbers of the tire-tread type are not appreciably influenced by the direction of the grain. Consequently, it is considered satisfactory to test such rubbers by using the normal (edge) type of specimen, prepared by vulcanizing, in a suitable mold, a disc cut from a sheet of the unvulcanized stock about 13 mm. thick.
Determination of Resistance to Abrasive Wear. X. Investigation of the Durability of a Bonded Abrasive Wheel on the Du Pont Machine
Authors: Newton R. G. , Scott J. R. 
Published: February 2011

Abstract
The results reported here entirely confirm those of Lambourn, who found that marked deterioration occurred with all the types of abrasive wheel which he used. In the present investigation on a bonded wheel, it was concluded that the wheel was appreciably less abrasive after each period of. 50 hours' wear, while Lambourn concluded that one side of a wheel can be used for a period of two months when subjected to 40 hours of wear per week. Lambourn also concluded that the deterioration is caused by smoothing or disintegration of the abrasive particles and not by clogging with rubber dust, and points out that variation in abrasive wear can be compensated by daily tests on samples of a standard compound. He also states that a grain coarser than 24 should not be used, since the abrasion is too rapid. Since the standard emery papers vary among themselves, and the bonded abrasive wheel deteriorates when it is used, it is evident that attention should be paid to the statistical planning of these tests, so that these factors can be reduced or eliminated. The coefficient of variation of a test result, i.e., the mean of three 10-minute runs, each on duplicate specimens, (six individual readings) as normally measured, seems to be independent of the type of abrasive employed (emery papers or bonded disc) and the uncertainty of the result is about ±5 per cent when measured on the basis of volume loss per hour and about ±3.5 per cent when determined as the volume loss/H.P.-hr. Test results will therefore be required to differ by about 7 and about 5 per cent, respectively, for a significant difference to be demonstrated.