bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Petroleum Products on Buna-S Vulcanizates
Authors: Morris Ross E. , Mitton Philip , Montermoso Juan C. , Werkenthin Theodore A. 
Published: February 2011

Abstract
The authors believe that the tear resistance data presented in this paper should be kept in mind by anyone contemplating the use of Buna-S in applications where occasional contact with petroleum products may occur. The coincidence of the following three conditions on the surface of a Buna-S vulcanizate will amost certainly lead to a serious tear: 1. Cracking (weather cracks, cuts, gouges, snags). 2. Wetting with petroleum products, particularly the lighter variety. 3. Flexing, static or dynamic. The tear will probably continue through the object until the flexing stress is relieved or until a fabric insert is reached. Thus, a tire tread would be torn through to the breaker fabric.
Nitroparaffins in the Rubber Industry
Authors: Campbell A. W. , Burns J. W. 
Published: February 2011

Abstract
A recent development in the field of industrial chemicals which has met with widespread interest is the first commercial production of nitroparaffins in 1940. The announcement of nitroparaffins to industry was followed by extensive investigations in industrial and research laboratories of the suitability of these compounds in a wide variety of applications, including many in the field of rubber technology. It is the purpose of this paper to summarize the more promising applications of the nitroparaffins in the rubber industry which have so far been reported.
S. K.—The Russian Synthetic Rubber from Alcohol. A Survey of the Chemistry and Technology of the Lebedev Process for Producing Sodium-Butadiene Polymers
Authors: Talalay Anselm , Talalay Leon 
Published: February 2011

Abstract
The question of producing synthetic rubber industrially was raised in Russia as early as 1918, and was fostered principally by the quest of the U.S.S.R. for economic independence. Having recognized that 1,3-butadiene is one of the simplest organic compounds capable of being polymerized to a rubberlike substance, the Russian Government provided funds for research in two directions: (1) To investigate the possibility of obtaining butadiene from a mixture of ethyl alcohol and acetaldehyde, according to the method suggested by Ostromislensky in 1915, for which purpose a pilot plant was erected in Moscow at the Bogatyr Rubber Company. (2) To continue work started in 1915 by B. V. Buizov in the laboratory of the Leningrad Treugolnik Rubber Plant, using petroleum products as a source of butadiene. By 1922 the Moscow plant had proved that Ostromislensky's process had no industrial future, for it yielded only 5 to 6 per cent of butadiene instead of the 15 to 18 per cent originally expected. The experimental station operated by Buizov had likewise met with little success by 1925. Early in 1926, therefore, the Superior Economic Council of the U.S.S.R. announced an open competition for the best industrial method of producing synthetic rubber, setting January 1, 1928 as the deadline. The qualifying conditions were rather exacting. They specified that the synthetic rubber should be neither inferior in quality to, nor substantially different in price from, natural rubber. Aside from a detailed description of the process and a two-kilogram sample of the synthetic product, the competition called for plans of a complete factory layout for its manufacture.
The Interaction between Rubber and Liquids. II. The Thermodynamical Basis of the Swelling and Solution of Rubber
Authors: Gee G. 
Published: February 2011

Abstract
It has been the purpose of this paper to show that the general phenomena of solubility and swelling of rubber could be understood on the basis of the detailed results found experimentally for the rubber-benzene system. Using no arbitrary constants which cannot be related to experiment, temperature coefficients of solubility of the right order of magnitude are calculated. It is clear that the qualitative agreement of this treatment with the meagre experimental data at present available must not be taken as evidence of the accuracy in detail of the equations employed for the heat and entropy of solution. This paper is based on work carried out under the programme of fundamental research on rubber undertaken by the Board of the British Rubber Producers' Research Association.
Swelling of Synthetic Rubbers in Mineral Oils. Swelling in Mineral Oils Containing Polyolefins and in Mixtures of Nujol and Biphenyl
Authors: Powers P. O. , Robinson H. A. 
Published: February 2011

Abstract
The true cloud temperature of a 50–50 weight mixture of aniline and mineral oil is a reliable index of the amount of swelling a synthetic rubber undergoes when immersed in mineral oil. This result is also true of mineral oils which contain polyolefins. Since the presence of both haze and cloud points is characteristic of such oils when mixed with aniline, a method has been worked out for distinguishing between them. Conversely, the presence of both haze and cloud points is believed to be indicative of the fact that polyolefins have been added to the mineral oils. The addition of polyolefins to mineral oils reduces the tendency of those oils to swell synthetic rubbers. The logarithm of the percentage swelling varies inversely with the aniline point. Although mixtures of Nujol and biphenyl can be duplicated fairly well, they offer no advantage over mineral oils for testing the tendency of synthetic rubber compositions to swell. Although the logarithm of swelling decreases as the 50 per cent aniline of the mixture increases, the relationship is not the same as that found for mineral oils. for evaluating behavior under service conditions, immersion tests in oils having the same aniline point as oils which may be encountered in service are believed to be more reliable and more significant.
Solubility of Polybutene in Pure Solvents
Authors: Evans H. C. , Young D. W. 
Published: February 2011

Abstract
During the past few years interest in the preparation and properties of long-chain polymers has been intensified because of their importance in the manufacture of improved petroleum products, plastics, and chemical-resistant paints. Materials such as polybutene and rubber form solutions, the viscosities of which increase rapidly with concentration. Typical viscosity-concentration data on dilute solutions of polybutene have been published. A number of workers have determined the viscosities of several polymers in dilute solutions, and from these investigations equations have been proposed for expressing viscosity as a function of molecular constitution. One of the most important considerations has been the question whether very high polymeric substances exist in solution as long macromolecules, completely dispersed, or as aggregations of much shorter molecules associated in the micellar state. Staudinger, one of the chief proponents of the former view, carried out a large amount of work on the viscosity of solutions of such linear polymers. His conclusions regarding chain length were based almost entirely on such measurements interpreted on the basis of the viscosity relation:
Molecular Structure and Rubberlike Elasticity. III. Molecular Movements in Rubberlike Polymers
Authors: Bunn C. W. 
Published: February 2011

Abstract
In Part I of this work, the crystal structures of β-gutta-percha, rubber and polychloroprene (deduced from x-ray diffraction photographs) were described. In pursuance of the idea that rubberlike properties are due to molecular flexibility which result from the swivelling of the chain units around single chain bonds, it is necessary to consider which chain-bond positions are the most stable and what hindrances there are to rotation away from these positions. The question of the most stable bond positions was considered in Part II. I now consider the evidence for the occurrence of rotation in rubberlike substances, the hindrances to rotation in different molecules, their effect on the crystallization or melting temperature, and the explanation of the mechanical properties of these substances in terms of structure and molecular movement, both above and below the crystallization temperature. Rubber is noncrystalline and elastic at room temperature; but on cooling below 0° C it crystallizes, and in that condition has the mechanical properties of gutta-percha; i.e., a frozen specimen no longer has enormous elasticity, but it can be drawn or rolled out irreversibly, whereby the crystals become oriented. Conversely, if gutta-percha is wanned to 70° C, it becomes amorphous (transparent, optically isotropic and noncrystalline), and its mechanical properties are then like those of rubber—it is soft and elastic. The difference between the two substances thus appears to be essentially a difference of crystallization temperature. These crystallization temperatures are remarkably low; e.g., polyethylene, (—CH2—CH2—)n, of comparable molecular length, crystallizes at 115–125° C. In attempting to understand rubberlike elasticity in terms of molecular behavior, the first question is why are the crystallization points of such enormous molecules so low, and why is the crystallization point of the cis-form of polyisoprene (rubber) lower than that of the trans-form (gutta-percha).
Constitution of Three-Dimensional Polymers and the Theory of Gelation
Authors: Flory Paul J. 
Published: February 2011

Abstract
In three-dimensional polymerizations, gelation is due to the formation of network structures of indefinite extent. These giant structures make their appearance when the degree of branching or cross-linking of the polymer chains exceeds a critical value. Gelation may be considered analogous to explosion in gas-phase reactions propagated by chains which undergo branching. After gelation has occurred, the sharp distinction between gel and sol is analogous to the demarcation between a liquid and its saturated vapor. Observed average molecular weights of three-dimensional polymers must be interpreted with extreme caution, owing to the peculiarity of the distribution of species in the vicinity of the gel point. Applications of the theory to raw rubber, protein gels, and inorganic gels have been discussed.
Rubber Analysis of Plants in South Carolina
Authors: Mitchell J. H. , Rice M. A. , Roderick D. B. 
Published: February 2011

Abstract
In 1930 and 1931 some plants growing in the vicinity of Clemson, South Carolina, were collected and analyzed for the presence of rubber. The plants were collected and identified by M. A. Rice, the chemical tests being made by the other two authors. The results are presented below. The figures given at the right show the percentage of rubber in each case. All determinations were made on a basis of air-dry weight.
A Low-Temperature Stiffness Test for Elastomers
Authors: Morris Ross E. , James Robert R. , Evans Edward R. 
Published: February 2011

Abstract
Most synthetic vulcanizates stiffen more than natural vulcanizates at low temperatures. This behavior has aroused considerable interest in the development of suitable tests for the cold resistance of synthetic vulcanizates. Inasmuch as all rubbers gradually stiffen and finally become brittle as the temperature is lowered, two general types of cold resistance tests have been developed, viz., stiffness tests and brittleness tests. The stiffness tests involve a quantitative measurement of the resistance to deformation of the specimens; the brittleness tests consist in determining the temperature at which the specimens will fracture when rapidly bent. We are concerned here only with stiffness testing.
Effect of Temperature on the Vibration Characteristics of Natural and Synthetic Rubbers
Authors: Morron J. D. , Knapp R. C. , Linhorst E. F. , Viohl P. 
Published: February 2011

Abstract
The results of this work have been to show, that the effect of temperature on the functions of vibration insulators is much greater than would be supposed from the type of tests which have become more or less common in the industry for determining the effect of low temperatures on various elastomers. It has shown also that natural rubber is the outstanding material for vibration insulation at subnormal temperatures. The substitution of any of the synthetics for natural rubber is a problem which requires not only a thorough study of compounding, but also of the practical conditions under which the particular mounting or insulator is supposed to function. An improvement in vibration insulation over a wide range of temperatures may be obtained by means of increased initial deflection. A critical point, called the “barrier point”, which depends not only on the compound but on the design and application of the mounting, is defined. New laboratory methods have been devised to obtain information which design engineers can apply to practical problems. This equipment actually shows the percentage of transmission of vibration. New equipment for the determination of stress-strain curves and tensile tests at all temperatures are likewise described and their uses explained. We hope that the simple, yet accurate instruments which have been devised from commonly available materials will be of some encouragement to others who wish to investigate the properties of different elastomers over a range of temperatures, but are hampered by the limitations of priorities, expense, and the fact that there is a lack of suitable equipment on the market for such investigations.
Surface Film Thicknesses of Polymeric Substances in Relation to Molecular Structure
Authors: Wall Frederick T. , Zelikoff Murray 
Published: February 2011

Abstract
It is well known that certain compounds, such as long chain fatty acids, can form monomolecular films on water and that the areas of such films can be related to the dimensions of the molecules. Certain polymeric substances, including cellulose derivatives, proteins and the polymer of ω-hydroxydecanoic acid likewise form stable films whose areas can be conveniently measured. At this time we wish to report that we have prepared films of some rubberlike polymers as well, and that the results appear to give useful information about their molecular structures, particularly in relation to branching.
Effects of Molecular Structure on Physical Properties of Butyl Rubber
Authors: Flory Paul J. 
Published: February 2011

Abstract
The investigation was undertaken in an attempt to establish the fundamental connections between the physical properties of a typical vulcanized rubberlike polymer and its chemical structure. The structural variables to be considered are the molecular weight of the “primary molecules” entering the vulcanizate, their molecular-weight distribution, and the concentration (or frequency) of cross-linkages introduced during vulcanization. The molecular weights of Butyl rubbers were determined by previously established procedures ; the effects of molecular-weight heterogeneity were suppressed by careful fractionation from very dilute solution. An indirect method, based on the theory of gelation and on the observation of critical molecular weight for incipient gelation (partial insolubility) in “vulcanisates” formed when the cross-linking capacity is fixed, was employed to determine the frequency of occurrence of cross-linked units—a quantity not hitherto evaluated in a vulcanized rubber. In representative pure-gum vulcanizates of Butyl the molecular weight per cross-linked unit ranges from about 35,000 to 20,000, depending (inversely) on the diolefin content of the raw rubber. Micro compounding and testing procedures have been devised for evaluating the necessarily small samples ob- tained in fractionation. Complete evaluation of tensile strength, stress-strain characteristics, swelling in solvents, and creep rate can be obtained with as little as 3 grams of rubber. Results are no less reproducible than those obtained with conventional procedures requiring 50 grams or more. A number of rela- tionships between vulcanizate structure and physical properties have been established. The feasibility of a rational approach to the interpretation of properties of rubber vulcanizates in terms of molecular structure has been demonstrated.
Electrically Conductive Rubber
Authors: Bulgin D. 
Published: February 2011

Abstract
Carbon particles in rubber are at first distributed as individual particles by the shearing action of milling, but the individual particles are in a state of Brownian movement due to the kinetic energy of the system. This causes the particles to drift about at a rate determined by the size of the particles, or particle aggregates, and the effective viscosity of the segments of the rubber molecules which is less than one hundredth of that of bulk rubber. The particles thus soon come into contact with each other, and since they are of a disordered crystalline structure and possess relatively high free surface forces, they cohere. The mobility of the aggregates of the particles is much less than that of the individual particles, due to their large size and size relative to that of the rubber molecules, so finally they are relatively immobilized into a scaffoldlike structure of carbon particles. This structure can be broken by external forces, and the broken structural units reform in vulcanized rubber to a structural state at a rate, and to an extent determined by the kinetic energy of the system. The idea of increasing structure formation with rise in temperature is apparently contrary to the kinetic theory, but the persistance of a stable conductivity value in passage from a high to a lower temperature rules out particle motion as the prime cause of conductivity. Furthermore the attainment of a discrete value for the conductivity (Figure 19) at any temperature rather than an alteration of the rate of change towards some maximum value, suggests that temperature activated energy barriers exist—possibly between the carbon and the rubber—which have to be broken before the carbon particles are free to move. Such a system explains the conductive properties of carbon-rubber mixes containing carbon particles of 250 to 300 A.U. diameter, but the properties of systems containing carbons of greatly different particle size may be considerably different. There is some evidence that the cohesion of carbon particles into structural units is sufficiently high to withstand the shearing forces involved during milling and processing treatments of unvulcanized rubber, and so carbon, structure formation from individual particles is of an irreversible nature. As the structural units grow in size under the influence of the kinetic energy of the system they become increasingly less mobile. This gives rise to permanent reduction in conductivity if the structure built up is violently disturbed; for example, if unvulcanized rubber is remilled after appreciable structural formation has taken place.
The Course of Autoöxidation Reactions in Polyisoprenes and Allied Compounds. XI. Double-Bond Movement during the Autoöxidation of a Monoölefin
Authors: Farmer E. Harold , Sutton Donald A. 
Published: February 2011

Abstract
In an earlier part of this investigation it was shown that the autoöxidation of Δ1,4-diene8 and Δ1,4,7-, etc., polyene compounds produces peroxido derivatives containing conjugated units, and to explain the formation of the latter a reaction-mechanism was proposed which postulated the detachment of hydrogen atoms from the reactive methylene groups under the action of molecular oxygen, and subsequent rearrangement of the resonating radical residues before oxygen and, finally, hydrogen combine therewith to give hydroperoxides: (see PDF for diagram) It was recognized that, if this mechanism is valid for methylene-interrupted diene or polyene systems, it might reasonably be expected to apply also to the formation of hydroperoxides by the action of oxygen either on simple olefins or on polyolefins containing two or more methylene groups between the double bonds. To demonstrate successfully that even the simplest olefin system capable of hydroperoxidation can give both of the oxygenated forms (A) and (B):
Elastic Deformation and Molecular Weight in Polyisobutylene
Authors: Rehner John 
Published: February 2011

Abstract
Although various properties of high polymers are known to depend on molecular weight, there appear to be no published data which show explicitly how the molecular weight of a rubber-like substance influences the modulus of high elasticity, even though a psychological perception of some such relationship has long existed. Also, the various expressions that have been derived by statistical methods contain molecular weight as a factor ranging from an inverse first power up to inverse higher fractional powers. Some time ago a need arose in this laboratory for estimating the average molecular weights of samples of polyisobutylene by a rapid procedure. Because of the slowness of polymer dissolution, methods based on measurements of the polymer in the dissolved state had to be ruled out and an investigation was, therefore, made of the rate of compression of a variety of samples in a Williams parallel-plate plastometer. It was found possible to render negligible the viscous component of deformation by using a sufficiently high compressive load and by limiting readings to an interval of about one minute. When the observed deformation values were plotted against the logarithm of time, straight lines were obtained. The slopes of the lines could be correlated, at least approximately, linearly with the reciprocal average molecular weights of the samples.
Applications of Ultraviolet Spectrography. A Study of Some Accelerators
Authors: Dufraisse Charles , Houpillart Jean 
Published: February 2011

Abstract
Not only is the problem of determining the compounding ingredients originally present in a rubber mixture by an analysis of the vulcanized product of interest from a technical point of view, but it also is of importance from the theoretical point of view to know what becomes of these ingredients as a result of the thermal effects of vulcanization. This is particularly true of that class of ingredients which function as accelerators of vulcanization. Chemical methods which are applicable to this problem are in all cases very complicated and are inconvenient in various ways. For some ingredients there are no methods at all avaifable. Accordingly it was thought that a study of ultraviolet spectra, the general principles of which have already been described and which have already been utilized by Jarrijon for the determination of anti-oxygenic substances, might offer a more rapid and more reliable means of attaining the desired end. The aim of the experiments to be described was simply to show what is to be expected of the method in this particular practical application. The study was devoted to three accelerators: diphenylguanidine, benzothiazyl disulfide, and mercaptobenzothiazole.