bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of the Types of Rubber and Carbon Black on the Formation of Carbon-Rubber Gel
Authors: Chernykh Z. V. , Epshtein V. G. 
Published: February 2011

Abstract
1. Carbon-rubber gels are formed in mixtures containing all the types of carbon black tested (channel, acetylene, nozzle, furnace, thermal) and not only active carbons. 2. The amount of carbon-rubber gel formed depends on the amount of carbon black added. With carbon blacks which readily form continuous carbon structures (channel, acetylene) the amounts of gel are greater than with nonstructural blacks, for the same amount of black added. 3. The amount of gel is greater in synthetic than in natural rubber mixtures. 4. More intense extraction conditions do not cause disappearance of the gel, but increase the amount of bound rubber and decrease the amount of carbon in the gel. 5. The carbon-rubber gels formed from structural carbons contain larger amounts of bound rubber. 6. It is suggested that bond stability between carbon black particles (characterized by the formation of a carbon black structure) is one of the basic causes of carbon-rubber gel formation.
Vulcanization of Elastomers. 22. Thermal Vulcanization of Synthetic Rubbers. I
Authors: Scheele Walter , Stemmer Hans Dieter 
Published: February 2011

Abstract
In this work, the kinetics of the thermal vulcanization of Perbunan were studied with and without additives. The following results were obtained : 1. The pure thermal vulcanization of Perbunan is a very slow process which obeys a second order rate law. A limiting value of the crosslinking (reciprocal limit of equilibrium swelling) is reached, which limit is independent of the temperature. The activation energy is 23.3 kcal/mole. 2. The thermal vulcanization can be inhibited by hydroquinone but not by benzoquinone. 3. The thermal vulcanization of Perbunan can be considerably accelerated by MBTS, and other materials, and the reaction also follows a second order course. The activation starts suddenly after the expiration of an induction period, which decreases with increase in temperature. The activation energy is about 27 kcal/mole. 4. In a thermal vulcanization accelerated with MBTS, a portion of the MBTS is changed over into MBT ; the amount changed is independent of temperature. Perbunan takes up MBTS in the form of molecular fragments, in stable combination. 5. The reduction in MBTS (which falls to zero) and the increase in MBT follow a first order reaction and have the same activation energy which is also identical with the energy of activation of the accelerated crosslinking. The formation of MBT is the slower of the two reactions. 6. The rate constants for the decrease in MBTS and for the increase in MBT are independent of the starting amount of MBTS, and hence we consider that this is a unimolecular process (homolysis). 7. The rate constant for the second order crosslinking reaction increases with the square root of the initial benzothiazolyl disulfide content. 8. It is indicated that the above data must be explained, with the aid of experience in the realm of polymerization kinetics. The investigations are being continued.
The Tensile Strength of Elastomers According to Current Theories
Authors: Bueche F. 
Published: February 2011

Abstract
In summary, it is probably true to say that the basic mechanisms responsible for the tensile strength of rubbers are now mostly known. Some disagreement exists concerning the exact role played by crystallinity and filler action. Opinions concerning the way in which the fracture propagates through the sample also differ. It is clear that all the present theories concerning tensile strength are inadequate in many ways. Although the basic ideas involved may be quite correct, much refinement in these theories is still needed. They are only rather crude first approximations to a fully successful theory of tensile strength. It is hoped that this review has been successful in pointing out the successes and failures of current theories so that improvements may be made in them.
Analysis of Rubber
Authors: Burger V. L. 
Published: February 2011

Abstract
In this paper it has been assumed that a completely unknown vulcanized sample is in question for analysis. Although this occurs very rarely in practice it is thought that such an approach would bring out the more important factors in desirable sequence. Thus, although general sources of information are worth first consideration, one might well begin an analysis with identification and determination of elastomers and continue with analyses for sulfur in various forms, accelerators, activators, antioxidants, reinforcers, fillers, etc. In a later section some attention will be given to analyses of importance as rubber goods are being manufactured; that is, tests on crude rubber and some of the principal compounding materials.
The Preservation and Concentration of Hevea Latex
Authors: McGavack John 
Published: February 2011

Abstract
Some twenty years ago the author stated that, “in the simplest form latex at the time of tapping may be defined as an aqueous buffered neutral system containing water-soluble crystalloids and fatty acid esters, in which small rubber particles are dispersed by means of a vegetable protein—said protein operating on the basic side of its iso-electric point”. Since that time we have had more information about the crystalloids and about the fatty acid esters but essentially the definition still holds. He also went on to say, “it is desired to use this word ‘preservation’ in its broad sense, that is, the maintenance or improvement of the system in all of its aspects … by the term preservation we are including not only methods that prevent bacterial action or guard against outside infection, but also methods which involve the use of actual stabilizers for the improvement of mechanical stability. In the first case we deal with disturbances that occur within the material itself. In the second case we deal with disturbances that occur either within or without. It is essential that a preserving substance should prevent bacterial action or fermentation of the protein or like materials. It is also essential to maintain the original state of dispersion when any serious stress is put upon it”. In this article we will attempt to outline the more recent, broader aspects of preservation which are essential to the commercial use of natural latex.
Effect of Oxidation of Rubber on the Kinetics of Its Swelling
Authors: Gul V. E. , Khodzhaeva I. V. , Dogadkin B. A. 
Published: February 2011

Abstract
1. Swelling of rubber during reaction with oxygen is described by a kinetic curve. After a sharply rising segment, corresponding to the diffusion of the solvent, the curve has a practically linear segment, reflecting a slow change of the degree of swelling due to the oxidation processes which accompany swelling. 2. The swelling maximum of rubber in a polar solvent when the oxidation effect is disregarded, corresponds to the molecular weight, degree of dispersion, and other structural properties of the rubber. The slope of the linear segment of the kinetic curve of swelling can serve as a characteristic of the resistance of the rubber to oxidation.
The Effect of Ozone on Neoprene Vulcanizates and the Influence of Some Protective Agents and Fillers
Authors: Hartmann A. , Glander F. 
Published: February 2011

Abstract
In this investigation an attempt was made to show a certain analogy between the nature of the phenomenon of the crystallization of an undercooled melt and ozone crack formation in stretched natural or synthetic rubber, in order in this way perhaps to have some starting point for a more detailed experimental investigation of these interesting problems. At the same time the observed qualitative differences in the effects of ozone on natural rubber vulcanizates and on Neoprene vulcanizates might be explained. In the experimental part it is first shown, with the help of a simplified experimental method, that the rate of crack growth can be considerably reduced by the presence of protective agents. In addition, a great change in the temperature dependence of crack growth is observed under certain conditions. It can not yet be decided whether or not the rate of nuclei formation is similarly influenced. Furthermore, vulcanizates containing different fillers and different Neoprene contents have been examined.
Stress Relaxation of Vulcanized Rubber in Compression and Tension
Authors: Eller S. A. 
Published: February 2011

Abstract
Stress relaxation is an important consideration in determining the suitability of gasket materials for Navy door hatches, pipe lines, and similar applications. In view of this, the Material Laboratory, New York Naval Shipyard, has devoted considerable time and effort to the design of equipment to measure stress relaxation of rubber materials deformed in compression and in tension.
Reinforcing Effect of Condensation Polymers on Rubber in Connection with Their Particle Size
Authors: Houwink R. , van Alphen J. 
Published: February 2011

Abstract
It is still an open question to what extent the reinforcing effect of a filler in rubber is due to physical or chemical bonds. There is abundant evidence that the reinforcing effect with regard to modulus, tear strength, and abrasion resistance increases with decreasing particle size. Arguments have been brought forward, however, that below a certain particle size this reinforcing effect diminishes. In most of the experiments involved, carbon black has been used as a filler. In the present paper, data regarding the reinforcing effect of some condensation resins of different particle size are presented in order to bring more light on these questions.
Effect of Heat Treatment on Reinforcing Properties of Carbon Black
Authors: Schaeffer W. D. , Smith W. R. 
Published: February 2011

Abstract
The high degree of stiffness or modulus which reinforcing carbon blacks impart to rubber has often been associated with reinforcement. Modulus appears to be associated with the chemical nature of the carbon black surface ; when the carbon black surface is cleaned of combined oxygen and hydrogen, a drastic drop in modulus occurs, and this is not accompanied by an equally drastic decrease in tire road wear. Reinforcing and semireinforcing carbon blacks have been heat-treated at successive increments through a temperature range of 1000° to 2700° C. Treatment up to 1500° results in removal of all combined oxygen and hydrogen, followed by an increasing degree of graphitization at higher temperatures. These carbon blacks have been compounded in a standard natural-rubber compound and properties evaluated. Modulus is profoundly altered by the chemistry of the carbon surface. Electrical resistivity passes through a minimum at 1500° C. Scorchiness or premature vulcanization improves with removal of volatile matter. The degree of graphitization of the carbon has only a minor effect on rubber properties. A highly graphitized carbon black still imparts a high degree of resistance to abrasive wear to tire treads.
Studies of the Vulcanization of High Elastic Polymers. III. Vulcanization of Natural Rubber with Thiuram Disulfides. Part 3
Authors: Scheele Walter , Lorenz Otto , Dummer Wilhelm 
Published: February 2011

Abstract
The present paper, which relates again to the problem of the kinetics of thiuram vulcanization, has led to the following results : 1. The velocity constants kTD of the interaction of tetramethyl-, tetraethyl-, and tetrapropylthiuram disulfides with natural rubber, which proceeds according to a first-order reaction, are linear functions of the reciprocal of the absolute temperature. This is true also of the velocity constants kDC of the dithiocarbamate formation. 2. The activation energies of both reactions are independent of the particular chemical constitution of the thiuram disulfide involved. 3. The different thiuram disulfides vary with respect to their reaction with rubber only by the steric factor. 4. The reaction mechanism of thiuram vulcanization has been discussed in the light of the results of the kinetic investigation. These studies are being continued.
Mechanism of the Exchange Reaction of Elemental Sulfur with Mercaptobenzothiazole
Authors: Blokh G. A. , Golubkova E. A. , Miklukhin G. P. 
Published: February 2011

Abstract
As was shown in our preceding study, a rapid exchange of sulfur atoms takes place between elemental sulfur and 2-mercaptobenzothiazole at temperatures corresponding to the conditions of vulcanization of rubber. This indicates the existence of a reaction between the atoms, and also the formation during this reaction of some kind of intermediate compounds. On the basis of the experimental data, it was established that only one of the sulfur atoms of mercaptobenzothiazole enters into the exchange reaction. It was natural to assume, in view of the technical properties of derivatives of mercaptobenzothiazole and its own chemical properties, that the sulfur of the sulfhydryl group takes part in the reaction. In fact, as is shown in another study, 2-mercaptobenzoxazole (I) has a stronger accelerating effect during vulcanization than 2-aminobenzothiazole (II) or 2-oxybenzothiazole (III). Furthermore, it is known that the sulfur in the sulfhydryl group of mercaptobenzothiazole and its derivatives is considerably more mobile than the sulfur in the ring, and is easily converted into other substituents.
Oxidation of Organic Sulfides. IV. Autoxidation of Cyclohex-2-Enyl Methyl Sulfide
Authors: Bateman L. , Shipley F. W. 
Published: February 2011

Abstract
Cyclohex-2-enyl methyl sulfide readily absorbs up to about 0.3 mole of oxygen per mole at 55° to yield a complex mixture. Cyclohexenyl methyl sulfoxide, 6-methylthiocyclohex-2-enone (VIII), cyclohexenone, cyclohexenol, water, and dimethyl disulfide have been identified and estimated approximately quantitatively. A reaction mechanism consistent with these and other experimental data is presented and discussed. Several new keto-sulfides which were required as reference compounds have been prepared and characterized; the sulfide (VIII) and its 3-methylthioisomer (III) show marked antioxidant activity.
Stress Relaxation of Peroxide and Sulfur Vulcanizates of Natural Rubber
Authors: Berry J. P. , Watson W. F. 
Published: February 2011

Abstract
Direct chemical investigation of the degradation of polymeric networks is usually impracticable owing to the experimental difficulty of insolubility and to the fact that reaction at only a small proportion of network units is sufficient to cause marked alteration of network structure. Resort has, therefore, to be made to the measurement of physical changes brought about by the chemical reactions. Change of tension at constant extension is a useful measure for this purpose, since statistical elasticity theory predicts a direct proportionality between the tension and the number of chains supporting the stress. The present purpose is: (1) to describe a stress relaxometer possessing certain advantages over previous models; (2) to report on the stress relaxation of peroxide-crosslinked rubber, which can be considered from a chemical viewpoint to be the simplest possible rubber network; (3) to point out some complications in the relaxation behavior of sulfur vulcanizates, and (4) to interpret the shapes of stress relaxation curves.
The Plasticization of Butadiene-Styrene Rubber
Authors: Karmin B. , Bets B. 
Published: February 2011

Abstract
1. The kinetics of the plasticization of a butadiene-styrene copolymer on a cold laboratory mill was studied. It was established that, at temperatures of 20–30° C, the plasticity rises steadily and that, consequently, under these conditions a monodirectional destructive process takes place. 2. The kinetics of plasticization of a butadiene-styrene copolymer was investigated in a laboratory banbury at 140° C, both with and without a plasticization aid (chemical). Plasticization at a high temperature is accompanied by the simultaneous operation of the two reactions of destruction and structure formation proceeding at cross-purposes, and may be described by a kinetic equation of the type: P=P0 (1+a⋅m)(1−b⋅n) 3. Plasticized rubbers obtained by breakdown on a cold mill have a smaller capacity for recovery than those obtained by treatment in a boiler or a banbury at temperatures above 120° C. 4. Plasticized rubbers obtained by milling on a cold mill give stocks with higher tensile strength and higher relative elongation than rubbers plasticized by hot treatment. 5. The high recovery capacity of rubbers plasticized at elevated temperatures and the lowering of the physical and mechanical properties of vulcanizates of those rubbers are explained by the branched molecules which they form during structure formation.
Glass Transitions in Polymer-Plasticizer Systems
Authors: Breitman L. 
Published: February 2011

Abstract
A summary of the investigation with the three types of diluent can he made with reference to Table VI. Hydrocarbon oils are more effective low-temperature plasticizers the lower their temperature coefficient of viscosity. Dibutyl sebacate is representative of crystallizing diluents. Such compounds are ineffective low temperature plasticizers unless, (a) at equilibrium, favorable thermodynamic parameters permit their existence as liquids in the polymer, or (b) the plasticizers tend to exist as the nonequilibrium, supercooled, liquids in the transition temperature region of the polymer. Particularly desirable are liquids with low apparent activation energies of viscosity and high miscibility with polymer. The four ester plasticizers, tributoxyethyl phosphate, dibutyl phthalate, dioetyl adipate, and dioctyl sebacate, have temperature coefficients of viscosity corresponding to a virtually common activation energy of 4.5 kilocalories. Here, the magnitude of diluent-polymer interaction, as indicated by volume increase measurements, dictates the order of effectiveness of the ester.
Failure of Stretched Rubbers under the Influence of Ozone
Authors: Zuev Yu S. , Kuzminskiĭ A. S. 
Published: February 2011

Abstract
Cracks perpendicular to the axis of stretching rapidly appear on stretched or bent rubbers exposed to the atmosphere (in the case of loaded vulcanized polybutadiene in the spring and summer months, in a few days). The fundamental cause of this phenomenon is the action of the ozone which is always present in the atmosphere in concentrations of several millionths of a per cent. However, we still lack any clear idea of the mechanism of this phenomenon, which would make possible a rational determination of ways to protect rubber. Questions related to the mechanism of ozone cracking of rubbers are discussed in this article on the basis of new experimental data. Causes of the formation of cracks. The presence of a stress is an indispensable condition for ozone deterioration. It is believed that the role of the stress can be summed up as follows. 1. The rubber molecules, under the influence of stress, are activated with respect to ozone. 2. The stress modifies the relation between the processes of structure formation and destruction in favor of the latter. For example, the stress may facilitate rupture of the chains during regrouping of the initial unstable ozonide into isoozonide.
Chain Scission in the Oxidation of Hevea. II.
Authors: Bevilacqua E. M. 
Published: February 2011

Abstract
Oxidation of natural rubber in latex yields two molecules of carbon dioxide, one of formic acid and one of acetic acid for each rupture of the hydrocarbon chain. The yields of these products can be interpreted readily by reference to the structure of the primary oxidation products of 1,5-diolefins established by Bolland and Hughes.
Study of the Thermal Oxidation of Butadiene-Nitrile Elastomers
Authors: Kuzminskii˘ A. S. , Popova E. B. 
Published: February 2011

Abstract
1. Processes of destruction and structure formation take place during the thermal oxidation of butadiene-nitrile rubbers. These processes take place simultaneously, and are the result of absorption of oxygen by the rubber molecules. The dominant process, which governs the changes in the physical and mechanical properties of rubber, is structure formation. 2. An essential difference between the behavior of vulcanizates of SKN-18 on the one hand, and of SKX-26 and SKN-40 on the other, is shown by heat oxidation and aging. Depending on the length of the induction period of oxidation inhibited by phenyl-2-naphthylamine, the nature of the consumption of inhibitor, and the rate of change of the equilibrium modulus, relaxation constant, and standard physical-mechanical properties during aging, the behavior of SKN-18 is practically the same as that of other butadiene polymers containing an equal number of double bonds in the main chains of the molecules. 3. It was established that, during thermal oxidation of butadiene-nitrile copolymers, acrylonitrile chains of the rubber molecules undergo conversion. 4. The formation of a certain quantity of substances soluble in methyl and ethyl alcohol during oxidation of nitrile rubbers is revealed, and it is established that substances present in these byproducts can inhibit the oxidation of rubber. 5. The resistance of butadiene-nitrile rubbers to thermal inhibited oxidation and aging of vulcanizates, which is greater than that of other butadiene rubbers, is explained by the formation from the rubber itself, during oxidation, of substances which are, in combination with phenyl-2-naphthylamine, very strong inhibitors of the oxidation process.
Colorimetric Determination of Phenyl-2-Naphthylamine in Rubber
Authors: Menšík P. , Broulík D. 
Published: February 2011

Abstract
A colorimetric method was worked out for the determination of the amount of phenyl-2-naphthylamine in butadiene-styrene copolymers based on the coupling reaction of phenyl-2-naphthylamine with diazotized p-nitroaniline. The method was found practically applicable. It is accurate, and the procedure is simple.
Electron Microscopic Studies of Fillers in Rubber. III. Effect of Milling on the Dispersion of Fillers
Authors: Suito Eiji , Arakawa Masafumi , Hasegawa Hiroshi , Furusawa Yonemasa 
Published: February 2011

Abstract
In the study of types of fillers which have a marked effect on the properties of rubber, information as to how the filler particles are dispersed in rubber is a prerequisite. The authors have already reported on the state of dispersion of various fillers in vulcanized rubber, observed under an electron microscope by the replica method. How the dispersion of these fillers affects the properties of rubber is an interesting problem. Since, in the earlier work, filler particles were observed to orient themselves in certain directions, in this report the relationship between the state of dispersion observed under an electron microscope of filler particles in rubber milled in different ways and the resulting characteristics of the mixtures were examined.
Chromatographic Determination of Rubber in Plant Latexes
Authors: Bernal Dorado E. 
Published: February 2011

Abstract
Partition chromatography on paper makes possible the separation of rubber hydrocarbon from latex. This method offers a means which is both simple and rapid for determining the presence of rubber in plant latexes and for the subsequent estimation of its percentage in a given latex. The method also gives a fraction which is composed of the nonrubber components. In addition to this, the method makes possible a comparison of the partition coefficients of rubber hydrocarbon isolated from latexes of different plants. Experiments are now in progress, the purpose of which is the application of the chromatographic method to the rapid determination of plant rubbers. By its simplicity, this method unquestionably has certain advantages in the identification of rubber in any particular flora and in studies of this hydrocarbon in its various phases of the biological cycle of the plant.