bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characteristics of Reinforcing Furnace Blacks Processing Shrinkage
Authors: Dannenberg E. M. , Stokes C. A. 
Published: February 2011

Abstract
A major technical development in the rubber industry has been the recent introduction of furnace blacks possessing rubber reinforcing properties in the range of channel blacks. The literature on the subject of reinforcing furnace blacks is rapidly expanding to satisfy the need for information on the compounding and rubber properties of these new products. Types of reinforcing furnace blacks are available which duplicate closely the usual rubber properties observed with channel blacks in vulcanized stocks. However, because of the flexibility of operation and the different types of raw material adaptable to the continuous furnace process, it is also possible to produce grades of reinforcing furnace blacks which differ markedly from channel blacks in rubber properties. The range of rubber stiffness and hardness obtainable with reinforcing grades of furnace blacks is much greater than with channel blacks, and although final approval of a grade of black for a particular application is based on service testing, the useful range of rubber product quality has been broadened by the introduction of new varieties of furnace blacks. Processing characteristics of carbon blacks may be described as the relative workability factors of rubber stocks in the sequence of operations preceding the completed manufacture of cured rubber articles. In those compounds where carbon black is a substantial component of the stock, the properties of the black would be expected to exert a major influence on processing. The work reported here is concerned with the effect of carbon black properties on the forming step of semifinished stocks, and includes a study of the processing shrinkage properties of carbon black loaded stocks.
The Compounding of Hard Rubber (Natural and Synthetic)
Authors: Gall W. Murray 
Published: February 2011

Abstract
Hard rubber, frequently called ebonite, is a material which has many desirable physical and chemical properties. The relatively new plastics industry has offered stiff competition, yet it is reasonably safe to say that, for certain applications, nothing else can be substituted for hard rubber and still maintain its unique properties. One of the principal qualities of this material is its finished appearance. When a high-grade ebonite compound is properly processed, it can be given a high lustrous finish which sets it apart from similar materials for beauty and richness. The highest grade of hard rubber is a compound containing only rubber and sulfur. It is in this type of compound that maximum physical properties and highest luster are found.
Dependence of Tensile Strength of Vulcanized Rubber on the Degree of Cross-Linking
Authors: Flory Paul J. , Rabjohn Norman , Shaffer Marcia C. 
Published: February 2011

Abstract
The suitability of disazodicarboxylates as quantitative cross-linking agents for the preparation of rubber vulcanizates of known degrees of cross-linking has been emphasized previously. In a recent paper we have presented the results of an investigation on the dependence of the equilibrium force of retraction on the elongation and degree of cross-linking of rubber and GR-S vulcanized with these compounds. The present paper reports an extension of these investigations of the relationship of physical properties of rubberlike materials to their network structure. Specifically, the tensile strength of azo vulcanized natural rubber has been explored as a function of the degree of cross-linking and of the extent of modification of the chain units. The tensile strengths of natural rubber specimens vulcanized to various extents using sulfur alone or sulfur in conjunction with various accelerators have been investigated in considerable detail recently by Gee, who has emphasized the critical dependence of the tensile strength on the degree of cross-linking. Values for the latter quantity, however, were deduced indirectly from the equilibrium force of retraction using the simple proportionality relationship between force of retraction and degree of cross-linking afforded by the theory of rubber elasticity. This relationship is known to be only approximately valid. Furthermore, the effects on the force of retraction of chain scission, which doubtless accompanied some of the vulcanizations to a considerable degree, were disregarded. For these reasons, Gee's values for the degrees of cross-linking occurring in his vulcanizates are only approximate estimates, and in a few cases they may be seriously in error. Nevertheless, the general character of the relationship between tensile strength and degree of cross-linking which he obtained is confirmed by our results on rubber samples quantitatively cross-linked with measured proportions of decamethylene-dismethyl azodicarboxylate.
Bonding of Rubber to Metal by Means of New Chemical Derivatives of Rubber
Authors: Gossot Jacques 
Published: February 2011

Abstract
The bonding process which has been described is of general application to all types of rubber mixtures, to metals, and to various other materials, without any change in composition of the bonding agent for the different materials. Although the problem of adhesion has been approached in this work only from the purely practical standpoint, it should be realized how little progress has been made in the theoretical knowledge of the problem. As a matter of fact, only a few authors have attempted to explain, on a basis of general concepts, certain special cases of adhesion, and there is still no real insight into the problem as a whole which might open the way to material progress. If one turns to the works of MacBain, Delmonte, and Buchan among the most important contributions to the phenomena of adhesion, the ultimate conclusion must be drawn that little has been accomplished in orienting investigations in this field toward more productive ends. From the physical point of view, particular attention must be paid to the condition of the state of the surface of the material to be bonded, to the surface tension, to the viscosity, and to the pH value of the adhesive. The chemical structure of the latter is that of a long-chain compound and, as has been proved conclusively in the present investigation, certain groups play a fundamental role, both in virtue of their chemical reactivity, and in virtue of the polar moment which they confer upon the molecule.
Color Reactions of Some Accelerators in Current Use
Authors: Schaefer W. 
Published: February 2011

Abstract
In taking an inventory, it was found that the labels on some accelerators had become lost, and the laboratory was called upon to identify the accelerators. However, little knowledge was available on this subject, so new analytical methods had to be developed. It was known that traces of copper can be detected by means of sodium diethyldithiocarbamate, the chemical nature of which bears a great resemblance to the compositions of Vulkazit-P, Vulkazit-P Extra-N, Vulkazit-774 and Thiuram. Hence it was to be expected that these accelerators would likewise react with copper salts. This was actually found to be the case. Encouraged by this success, a series of other accelerators were tested with the copper reagent, and it was found that every accelerator tested differed from all other accelerators in this reaction. This immediately offered a means of distinguishing some of the accelerators most widely used in the rubber industry.
The Estimation of Small Percentages of Rubber in Fibrous Materials
Authors: Blow C. M. 
Published: February 2011

Abstract
The estimation of the percentage of rubber in fibrous products treated, for example, with Positex involves several difficulties, and no one method can be adopted on account of the difference in behavior of the various fibers. The fiber may consist of protein such as silk, wool or other animal fiber, and leather, or cellulosic material such as jute, cotton, rayon, paper, kapok, etc. The rubber may be vulcanized or unvulcanized. In addition to fiber and rubber, the presence of other substances such as soap, fats, waxes, oils, dyestuffs, fillers, pigments, etc., must not be overlooked. The problem of analysis appears complex, but may be simplified in some cases by knowing, from the process of manufacture, the definite absence or presence of certain ingredients. The three techniques available are now discussed.
Time and Stress Effects in the Behavior of Rubber at Low Temperature
Authors: Beatty J. R. , Davies J. M. 
Published: February 2011

Abstract
The stiffening of rubberlike materials at low temperature involves several different phenomena, sometimes with their effects superimposed. One of these is crystallization. This is a rate process which is generally very fast at high stresses and very slow at zero stress. In these experiments at temperatures near −25° C and under a shear stress of about 148 lb. per sq. in. the dynamic modulus of the rubber increased at a rate convenient to study. Correlation with x-ray data showed that crystallization was very likely responsible for the increase in stiffness. The rate of change of stiffness increased rapidly with increase in applied stress, and there was no optimum rate at −25° C, as has been found for unstressed rubber. The degree of vulcanization influenced the rate of change, tighter cures giving smaller changes. Neoprene-FR, GR-S, and polybutadiene, which ordinarily show little evidence of crystallization, showed very definite, but small increases in stiffness. Mixing GR-S with natural rubber seems to limit the crystallization of the natural rubber rather effectively, but apparently Neoprene-FR does not mix intimately enough with natural rubber to affect the crystallization of the latter appreciably.
Flow Phenomena in Rubber Samples
Authors: Rössler Fritz 
Published: February 2011

Abstract
A more extended investigation was made of the surprising flow phenomena which were found in an earlier study of rubber at low temperatures. The tensile apparatus was reconstructed so that a dead-weight load could be applied to the rubber test-specimen. Determinations of the dependence of the rate of flow on time of stressing, initial elongation, magnitude of the stress, and temperature showed that a simple law can be derived for expressing the flow phenomena. Yield point, change in color, and deterioration in physical properties, as well as the reversibility of these phenomena were investigated and are discussed. The phenomena of flow at room temperature are expressed by the same constants as at lower temperatures. Only the effective stress increases at low temperatures and only by this change does flow become perceptible. Different types of rubber were compared, and all showed approximately the same value for the flow constant. The essential characteristics of the flow phenomenon can be explained, on a basis of the theory of highly elastic materials, by their microliquid state of aggregation. This applies to the high degree of dependence of the mechanical properties of rubber on the temperature.
Determination of the Molecular Weight of Rubber and Polystyrene by the Methods of Light Scattering and Osmometry
Authors: Dogadkin B. , Soboleva I. , Arkhangel'skaya M. 
Published: February 2011

Abstract
1. Experiments on the determination of the molecular weights of natural rubber and other high-molecular compounds by the methods of light scattering and osmometry are reported. 2. An osmometer of new design, suitable for determining molecular weights, is described. 3. It is shown that the method of light scattering yields values for molecular weights which are in satisfactory agreement with those obtained by the method of osmometry.
Infrared Studies of 1,2- and Trans 1,4-Structure of Polybutadiene and Butadiene-Styrene Copolymers Polymerized at Various Temperatures
Authors: Hart E. J. , Meyer A. W. 
Published: February 2011

Abstract
Infrared methods have been used in determining 1,2- and trans-1,4-addition in polybutadiene polymerized in the temperature range −19° to 97° and butadiene-styrene copolymers prepared at −18°, 5° and 50°. trans-1,4-Addition increases and 1,2-addition decreases with decreasing temperature of polymerization. At −19°, substantially all of the 1,4-addition product is present in the trans-1,4-form. Approximately 20 per cent 1,2-addition occurs at this temperature and is concluded to account for the major part of the non-crystallizable portion of polymers made at low temperatures. The influence of styrene on 1,2- and trans-1,4-addition in butadiene-styrene copolymers is also discussed. Free energy, heat and entropy of activation are calculated for 1,4- vs. 1,2-addition and trans-1,4- vs. cis-1,4-addition in the polymerization process.
Dependence of Elastic Properties of Vulcanized Rubber on the Degree of Cross-Linking
Authors: Flory Paul J. , Rabjohn Norman , Shaffer Marcia C. 
Published: February 2011

Abstract
The results reported above demonstrate a progressive increase in the force of retraction τ at fixed elongation with increase in the fraction p of the structural units which are cross-linked from ρ=0.10×10−2 to 3.0×10−2. Over this range, τ at 100 per cent elongation increases about thirteenfold. Swelling measurements indicate that the increase in τ with ρ continues over an additional tenfold range in ρ. Previous assertions that the modulus of elasticity of soft gum rubber vulcanizates depends largely on chain interaction and entanglements other than those imposed by the cross-linkages, and that the modulus is, therefore, not directly related to the degree of cross-linking, are without foundation. The statistical theory of rubber elasticity expresses the force of retraction as a function of the temperature, vulcanizate structure and elongation; no arbitrary constants are involved. The magnitudes of τ for α=2 are in remarkably close agreement with the predictions of the theory over most of the range in ρ. This fact is of the utmost significance in confirmation of the statistical theory of rubber elasticity and of the analysis of the network structure of vulcanized rubber. On the other hand, τ increases less rapidly with ρ than the direct proportionality prescribed by theory. Forces of retraction are higher than the theory predicts at low degrees of cross-linking, and an opposite deviation is observed for values of ρ greater than about 1×10−2. Previous observations on Butyl rubber, vulcanized to p values from about 0.16×10−2 to 0.28×10−2 indicated forces of retraction (for infinite molecular weight M) which exceed by about threefold those predicted from the theory. This deviation is decidedly larger than has been observed here in the same range for ρ. A substantial part of the discrepancy observed for Butyl rubber may have arisen from failure to secure elastic equilibrium, however. Deviations in the values of τ from theory probably originate largely from oversimplifications in the treatment of the network structure. Entanglements of the sort previously discussed tend to enhance the restraints imposed on the chains when the rubber is elongated. Their percentage effect should be greatest for low degrees of cross-linking, hence the observed τ values are higher than theory at low degrees of cross-linking. “Intramolecular” cross-linkages, yielding short-circuit structures contributing nothing to the elastic reaction of the network, should become increasingly important at higher degrees of cross linking. Such wastage of cross-linkages may account for the low values of τ obtained for higher ρ values.
Giuseppe Bruni 1873–1946
Authors: Schidrowitz Philip 
Published: February 2011

Abstract
Giuseppe Bruni, a pioneer in the development of structural chemistry and the chemistry of solid solutions and isomorphism, and also outstanding for his researches in the chemistry and technology of rubber, was born in Parma, Italy, in 1873, and died in Milan in 1946. The news of Bruni's passing did not, for some unexplained reason, become known to most of his many friends and admirers abroad until the end of 1949. After graduating in Parma in 1896, he joined the renowned Ciamician at Bologna University, where for nearly ten years he worked mainly on the nature and theory of solid solutions and of isomorphism. In 1908, he summed up his researches in this field in a monograph entitled “Solid Solutions and Isomorphism,” published in Germany under the title “Feste Lösungen und Isomorphismus.” He temporarily left Bologna to work with van't Hoff in 1900–1901, and the latter subsequently emphasized the importance of Bruni's researches in the following words: “Ce savant à contribué d'une partie prépondérante à l'adoption des lois sur les solutions solides et les mélanges isomorphes, qui, sans son intervention auraient été troublée par des notions confuses.” [This scholar and master has contributed in a major way to the establishment of the laws of solid solutions and of isomorphic mixtures, for without the part which he played, the formulation of these laws would have been beset by a confusion of ideas.] The year 1907 saw Bruni appointed to the Chair of General and Inorganic Chemistry at Padua, where for a decade he conducted researches on diffusion in the solid state, on the cryoscopic method, etc. In 1917 he was appointed Professor of General and Inorganic Chemistry at the Polytechnic School of Milan—an institution similar in character to the Massachusetts Institute of Technology. He held this post until shortly before his death. In the following, a brief résumé is given of his work in rubber science and technology.
The Degree of Crystallinity in Natural Rubber. III. Correlation between X-Ray and Density Measurements
Authors: Arlman J. J. 
Published: February 2011

Abstract
In 1925 Katz discovered the crystallization of stretched rubber. In the following years several investigators tried to determine the structure of rubber crystallites. The densities of the rubber crystallites calculated from the results of these investigations varied strongly. The results of x-ray and density measurements on crude rubber carried out by the author can be made to correspond only when the latter are based on the unit cell of Bunn. It is shown by experiment that, to measure the correct degree of crystallization, it is necessary to use monochromatic x-rays.
The Degree of Crystallinity in Natural Rubber. IV. The Degree of Crystallization in Frozen Raw Rubber and Stretched Vulcanized Rubber
Authors: Goppel J. M. , Arlman J. J. 
Published: February 2011

Abstract
An improved x-ray technique has been worked out to determine the degree of crystallinity in natural rubber. Inaccuracies which sometimes occur in quantitative x-ray measurements were eliminated, and it has been shown that the amount of crystalline rubber, both in frozen samples of raw rubber and in stretched vulcanized rubber, could be determined fairly accurately. More experiments were carried out and the results are described. These results, which confirm the current views on the problem of crystallization, point to relatively low degress of crystallization, even in highly stretched rubber, and they agree with some other experimental evidence and with a recent theoretical investigation.
The Degree of Crystallinity in Natural Rubber. V. A Discussion of the X-Ray Results on Natural Rubber in Connection with the Work of Flory, Gee and Wildschut
Authors: Arlman J. J. , Goppel J. M. 
Published: February 2011

Abstract
A recent theory, developed by Flory, makes it possible to calculate the degree of crystallization from thermodynamical measurements if certain parameters are properly evaluated. Such evaluation is possible by combining Wildschut's thermodynamical measurements with the x-ray results presented in previous papers. Thus the average length of molecule chains between cross-linkages can be derived; it closely corresponds to the results of swelling measurements carried out by Gee. Other parameters are also evaluated in agreement with their physical meaning.
The Reaction of Sulfur and Sulfur Compounds with Olefinic Substances VI. Factors Influencing Cyclic Sulfide Formation in the Reaction of Sulfur with Polyisoprenes
Authors: Bloomfield George F. 
Published: February 2011

Abstract
Cyclic Sulfides are to a large extent secondary products of the reaction of primarily formed intermolecular polysulfides with polyisoprene hydrocarbon, and undue prolongation of the time of reaction of sulfur with polyisoprenes favors cyclic sulfide formation and so reduces the cross-linking efficiency of the sulfur. Various accelerating substances markedly increase the cross-linking efficiency, either by permitting shorter reaction times to be employed, or by promoting a cross-linking rather than a cyclizing reaction of the sulfur. Thiuram disulfide accelerators in the absence of sulfur bring about cross-linking, the linkages being of C—S—C type rather than C—C.
Tensile Properties of Natural and Synthetic Rubbers at Elevated and Subnormal Temperatures
Authors: Boonstra B. S. T. T. 
Published: February 2011

Abstract
It is necessary to determine the physical properties of rubbers at relatively high temperatures when products made from them are to be used at such temperatures in actual service. The term heat aging is used when the vulcanizate is tested at room temperature, exposed to elevated temperatures for given periods of time, and then tested again at room temperature. The term high-temperature strength is proposed for values obtained when the vulcanizates are tested at the actual higher service temperatures. Effective comparison of natural and synthetic rubbers is best obtained by determining tensile product values, which are the result of the combining of tensile strength and elongation values. In the evaluating of vulcanizates of tire compounds of various rubbers, another factor must be taken into account. Synthetic-rubber tires develop more heat in service than do natural-rubber tires, and the former therefore generally operate at higher temperatures than do the latter. Synthetic-rubber tires therefore require a greater high temperature strength than do natural rubber tires, but, as has been shown, synthetic rubbers actually have a lower high-temperature strength. The part played by carbon black with respect to the tensile properties of some synthetic rubbers is considered that of a substitute for crystallization in natural and other synthetic rubbers, which substitute does not, however, possess the same favorable features. Carbon black even in noncrystallizing rubbers does not increase strength; it merely shifts the optimum strength value to a higher temperature so that this temperature is in the room temperature range. The temperature coefficient of strength for Butyl and Neoprene rubbers is so large at room temperature that a few degrees' difference in temperature causes large changes in strength. The tensile strength and elongation at break of these two rubbers decrease sharply between 20 and 40° C.
Flow Phenomena in Rubber. II. Flow Curves for GR-S Rubber
Authors: Treloar L. R. G. 
Published: February 2011

Abstract
The flow of GR-S at various temperatures was examined by means of the biconical rotor type of Mooney plastometer. Unlike the natural rubber previously studied, the shape of the flow curves was consistent with the Ostwald-de Waele relation. Values of activation energy for flow, determined from the temperature coefficient of flow rate (at constant stress), averaged 10.2 k.cal. per mole.