bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crosslinking of Unsaturated Polymers with Dimaleimides. II.
Authors: Kovacic Peter , Hein Richard W. 
Published: February 2011

Abstract
A study was made of the crosslinking of unsaturated polymers with dimaleimides representative of both the aliphatic and aromatic series. In the presence of catalytic amounts of dicumyl peroxide, dimaleimides functioned as highly effective cross-linking agents for natural rubber and SBR. Comparatively little crosslinking occurred in the absence of peroxide under thermal conditions. With peroxide as a promoter, monomaleimides and dimaleamic acids also crosslinked natural rubber, but to a lesser extent than did the dimaleimides. The chemistry of the crosslinking process is discussed, and correlations are drawn between the structure of the dimaleimide and vulcanizate properties.
Sulfur-Induced cis-trans Isomerization of Polybutadiene
Authors: Bishop William A. 
Published: February 2011

Abstract
Both high cis-1,4-polybutadiene and high trans-1,4-polybutadiene were found to isomerize when heated in the presence of elemental sulfur. The kinetics of the sulfur induced isomerization of high cis-1,4-polybutadiene were studied over a wide range of temperature and sulfur concentration and found to obey a first-order kinetic expression having an effective rate constant directly proportional to the initial sulfur concentration. The apparent activation energy was found to be 30.1 ± 0.4 kcal/mole. Isomerization was also found to be induced by dicumyl peroxide. A comparison of the mechanisms involved in the sulfur and peroxide induced isomerization indicate a basic difference in the nature of the initial interaction of the double bond with the sensitizing species. The initial interaction of the sulfur and the double bond is pictured as a π-complex that decomposes to a freely rotating radical, whereas the peroxide induced isomerization is presumed to involve direct radical addition to the double bond.
Compounding of cis-1,4 Polybutadiene for Tire Applications
Authors: Brown R. J. , Knill R. B. , Kerscher J. F. , Todd R. V. 
Published: February 2011

Abstract
cis-1,4-Polybutadiene is proving to be one of the most versatile compounding materials available to the tire compounder. It has characteristics as a polymer which make it acceptable as a replacement for either natural or synthetic rubber in tire applications. The successful use of cis-polybutadiene in this dual role, however, is dependent upon discovering its peculiarities and sensitivities and then exploiting them in that area of the tire where they are most applicable. Laboratory studies, confirmed by over three million miles of tire testing, have shown that in either passenger or truck tires the carcass durability can be substantially improved, operating temperature lowered, low temperature performance improved, and treadwear resistance increased when cis-PBD is properly used in the respective tire components.
Reactions of Polymers in Bulk. III. Influence of Specific Surface and of Filler Concentration on Deformation Behavior
Authors: Janacek J. 
Published: February 2011

Abstract
The deformation behavior of carbon black-filled vulcanizates depends—after elimination of the influence of the differences in chemical activity of the carbon black—on the product of the specific surface P of the carbon black and the nth power of its volume concentration c; for the correlation of the modulus M100, the Shore hardness, and the rebound elasticity the value n=2 was found. This statement holds true for carbon blacks of similar structure levels and of small enough specific surface that one can assume that it will not agglomerate to an appreciable extent.
Reactions of Polymers in Bulk. IV. Influence of Structure and Agglomeration of Carbon Black Particles on Deformation Behavior
Authors: Janacek J. 
Published: February 2011

Abstract
The deformation behavior of filled rubber vulcanizates depends on the degree of linkage of the carbon black particles and on their tendency for agglomeration. The significance of these factors is discussed with consideration of the specific surface of the particles, their concentration, the degree of crosslinking, the magnitude of the deformation and the character of the polymer system.
Crystallization Phenomena in Filled, Unstretched, Natural Rubber
Authors: Westlinning H. , Butenuth G. , Leineweber G. 
Published: February 2011

Abstract
In two previous communications it was shown that the “reinforcing effect” of active fillers is associated with the formation of highly resilient sheaths of low swelling capacity, surrounding the filler particles. In order to support this concept and to come closer to understanding the qualitative structure of this sheathing material, initial trials were undertaken in an effort to depict it directly with the microscope.
Tetramethylthiuram Monosulfide and Tetramethylthiuram Disulfide: Heats of Formation and the S—S Thermochemical Bond Energy
Authors: Good W. D. , Lacina J. L. , McCullough J. P. 
Published: February 2011

Abstract
The heats of combustion and formation were determined for tetramethylthiuram monosulfide [bis-(dimethylthiocarbamoyl) sulfide] and tetramethylthiuram disulfide [bis-(dimethylthiocarbamoyl) disulfide]. The S—S thermochemical bond energy in tetramethylthiuram disulfide was shown to be about the same as in normal alkane disulfides and in S8. Rotating-bomb combustion calorimetry was found satisfactory for compounds that contain both sulfur and nitrogen.
Reaction of Mercaptobenzothiazole with Rubber during Mastication
Authors: Chatterjee Pronoy K. , Sircar Anil K. 
Published: February 2011

Abstract
Mercaptobenzothiazole (MBT), determined amperometrically in the acetone extract from an unvulcanized rubber-sulfur-MBT mix shows a loss of about 13 per cent of MBT. The results improve slightly when mixing is carried out at a low temperature (10° C) or in an inert atmosphere. After exploring the various possibilities, e.g., oxidation of MBT to MBTS or reaction with rubber it was concluded that main loss of MBT is due to a side reaction with nonrubber ingredients, extractable with acetone. Total MBT recovered when mixed with acetone extracted pale crepe or with synthetic cis-polyisoprene is about 98 per cent. In the absence of sulfur no appreciable reaction takes place even when MBT is heated with rubber at 145° C for 5 hours.
Titrimetric Determination of N,N′-Disubstituted p-Phenylenediamines
Authors: Lorenz Otto , Parks C. R. 
Published: February 2011

Abstract
Three types of p-phenylenediamine derivatives used extensively as antioxidants and antiozonants in rubber compounds are N,N′-di-sec-alkyl-, N-sec-alkyl-N′-aryl-, and N,N′-diaryl-p-phenylenediamines. Available methods for these compounds are based mainly on a colorimetric determination of their colored oxidation products, the Wurster's salts or the p-quinonediimines. The deep coloration of the Wurster's salts was used as the basis of a spot test for the rapid detection of these diamines in rubber compounds. This test permits one to differentiate the three types of p-phenylenediamines. An investigation of the neutralization of p-phenylenediamines in nonaqueous solvents showed that N,N′-di-sec-alkyl- and N-sec-alkyl-N′-aryl-p-phenylenediamines could be determined readily in this way. The N,N′-diaryl derivatives did not give satisfactory titration curves because of their low basicity. By the addition of chloranil, however, diaryl-p-phenylenediamines were oxidized to the Wurster's salts with the formation of one equivalent of base which could be neutralized by acid. A similar procedure was applicable to the determination of N,N′-diaryl-p-quinonediimines, or mixtures of these diamines and diimines.
Tritium Tracer Study of Antioxidant Action in SBR
Authors: McHenry W. Dennis 
Published: February 2011

Abstract
Development of vulcanizates with good heat resistance has been a part of the program at this Arsenal's Elastomer Unit for some time. Freeman made a comprehensive evaluation of 63 commercial chemicals for use as heat stable inhibitors. A cadmium/barium fatty acid soap-chelator mixture was found to be the best heat stable antioxidant evaluated in the styrene-butadiene series of his investigation. Further work with this stabilizing system, by Testroet, in which its components were tested individually, disclosed this effect to be synergistic, as no significant protection was noted when the materials were used independently. An aid to the understanding of this synergism was sought in a radiometry study of the physical behavior of Cd/Ba salts of stearic and myristic acids (soaps) and pentaerythritol (chelating agent) during heat aging of an SBR vulcanizate.
Oxidation of Butadiene-Acrylonitrile Rubbers
Authors: Devirts E. Ya , Novikov A. S. 
Published: February 2011

Abstract
1. The authors investigate the inhibited oxidation of SKN-18, SKN-26 and SKN-40 butadiene-acrylonitrile rubbers in a micro-oxidation apparatus at various temperatures. 2. It is established that the rate of inhibited oxidation of butadiene-acrylonitrile rubbers is determined by their nitrile group content. On increasing the amount of acrylonitrile in the polymer the rate of oxidation decreases. 3. The energy of activation of inhibited oxidation of butadiene-acrylonitrile rubbers (29 to 30 kcal/mole) is calculated according to the Arrhenius equation. The energy of activation of inhibited oxidation of SKN rubbers is 5 kcal/mole higher than the energy of activation of inhibited oxidation of SKS-30 rubber and 10 kcal/mole higher than that of SKB rubber. 4. The structural changes in SKN rubbers in inhibited oxidation are determined by their nitrile groups. For SKN-26 and SKN-40 the predominant process in all stages of oxidation is the process of crosslinking. In the case of SKN-18 the process of degradation predominates at the beginning, and in the later stages the process of crosslinking. 5. A correlation is demonstrated between the behavior of SKN rubbers in oxidation and in thermal oxidative plasticization.
Faster Curing Butyl Rubber
Authors: Dorko Z. J. , Edwards D. C. , Lumb P. B. 
Published: February 2011

Abstract
For many years there has been need for polymers with the characteristics of butyl rubber but with appreciably greater rates of cure. Until recently, however, the range has been defined by PB-100 and PB-400 at the two extremes so far as our commercial products are concerned. This paper describes some of the products we are introducing to extend this range. First of all, the problems of producing faster curing butyl will be outlined. Butyl rubber is essentially polyisobutylene in which a small portion of isobutylene molecules is replaced by isoprene. These isoprene molecules supply the active sites for vulcanization, hence, in order to produce a faster curing butyl, the obvious approach is to make a polymer still essentially polyisobutylene, and containing a larger amount of copolymerized isoprene. This solution did not seem promising, owing to the serious molecular weight depressant effect of isoprene, and of the trace impurities present in the various feed streams. (It is worth noting that the addition of as little as 1% of isoprene to isobutylene reduces the molecular weight of polyisobutylene by a factor greater than 10.) We did, however, feel that a more complete knowledge of the chemistry of the polymerization system might yield a means whereby this poisoning effect would be overcome. In laboratory scale polymerizations, we therefore began a kinetic study of the copolymerization of diolefins with isobutylene under conditions similar to large scale commercial operations. The aim of this work was first to obtain information on the relative rates of all propagation and termination reactions, then to apply these data with the proviso that the engineering advantages of our present process were not lost. From this we hoped to determine whether conditions existed leading to higher unsaturation polymers with high molecular weight. The results of this study, which we intend to publish elsewhere at a later date in detail, have elucidated the order of the principal termination reactions, and have led to an economic process whereby copolymers of isobutylene with larger amounts of isoprene are now commercially available (in both 40–50 Mooney and 70–80 Mooney grades). The properties of the 40–50 Mooney polymers will now be described in comparison with existing grades, to show what properties are now available, and also the relationship between these properties and polymer unsaturation.
Nitrile Rubbers and Vinyl Polymer Mixtures
Authors: Almond C. Y. 
Published: February 2011

Abstract
The outstanding resistance to abrasion, oil, fire and ozone of vulcanized nitrile rubber/PVC blends has stimulated cable manufacturers throughout the world. In this paper the effect of polymer properties on mixing conditions is discussed and physical properties resulting from different mixing conditions reviewed. The physical (including electrical) properties of vulcanized and unvulcanized nitrile rubber/ PVC blends are related to the use of these blends in covering electric cables. Comparisons are made with other types of sheathing and insulating materials and existing potential uses of nitrile rubber/PVC blends in cable coverings are discussed.
Isolation from Vibration with a Mounting Utilizing Low- and High-Damping Rubberlike Materials
Authors: Snowden J. C. 
Published: February 2011

Abstract
This paper describes a theoretical investigation of the performance of an antivibration mounting utilizing elements of low- and high-damping rubberlike materials in parallel, arranged such that both materials experience the same strain. Knowledge of the dynamic mechanical properties of natural rubber and a high-damping synthetic rubber has enabled the behavior of the so-called parallel mounting to be estimated realistically. General expressions have been derived from which the response ratio of a parallel mounting employed in one- and two-stage mounting systems may be determined, once the variation with frequency of the mechanical impedance Zω of the foundation of the mounting system is known. The mounting systems have been assumed throughout to possess natural frequencies of 5 cps. To compare the response ratios of the mounting systems, a specific nonrigid foundation has been considered, namely, a simply supported beam possessing damping of the solid type. The beam possesses a “springlike” impedance at frequencies below its fundamental resonance, which is assumed to occur/at 50 cps. The ratio of the mechanical impedance of the beam to the value it takes at low frequencies is plotted in Figure 3 of Reference 1, through the frequency range 1–1000 cps. The mounted item is supposed to behave purely as a lumped mass. “Wave effects” that may occur in the rubberlike mount materials are disregarded. These materials are always assumed to behave in a linear manner.
Mechanical Properties of Rubber at High Rates of Elongation
Authors: Zhurkov C. N. , Sanfirova T. P. , Tamashevskii E. E. 
Published: February 2011

Abstract
1. The mechanical properties of rubbers undergo substantial changes in a range of elongation rates, depending on the nature of the rubber. 2. It is shown that a difference in the nature of the strength dependence on rate for noncrystallizable, crystallizable, and filled rubbers is induced by changes of structure of the material during stretching.
Elastomer Structure and Adhesion. I. Effect of Sulfur Vulcanization on the Adhesion of Rubber to Fiber Forming Compounds
Authors: Raevskii V. G. , Voyutskii S. S. , Livanova I. V. , Shteinberg Z. D. 
Published: February 2011

Abstract
1. A study was made of the effect of sulfur vulcanization of a rubber coating on its adhesion to fiber-forming polymers. 2. It has been established that there is a maximum degree of crosslinking of rubber during vulcanization and after attainment of this there is a sharp drop of the adhesion of the rubber to the fiber-forming polymers. 3. It has been established that for the rubbers investigated and fiber-forming polymers there is a value of the maximum degree of crosslinking (from the magnitude of Mc). It has been shown that this magnitude practically does not depend on the polarity, molecular weight, type of comonomer, and mobility of the segments of the molecules of the investigated elastomers. 4. It has been shown that all the experimental observations of this work are in complete agreement with the diffusion theory of adhesion.
Effect of Hydrogenation on the Properties of Polybutadiene Rubbers
Authors: Yakubchik A. I. , Reikh V. N. , Tikhomirov B. I. , Pavlikova A. V. 
Published: February 2011

Abstract
1. The properties of hydrogenated sodium polybutadienes of various degrees of unsaturation were studied. The tensile strength and relative elongation of the vulcanizates have minimum values when the degree of unsaturation has been decreased by about one half. Elasticity and gas permeability of the vulcanizates decrease and the hardness increases with diminishing unsaturation. The resistance to thermal aging also increases. Order in the polymer chains has a favorable effect on the relative elongation and tensile strength of vulcanizates even if it does not lead to crystallization. The improvement of the freeze resistance of vulcanizates made from hydrogenated sodium polybutadienes is associated with the internal plasticization effect. 2. Studies of the properties of hydrogenated cis-l,4-polybutadienes, which have appreciable crystallinity, showed that vulcanizate elasticity decreases while the hardness increases sharply with decreasing unsaturation. The rise of the glass transition temperature is due to increased rigidity of the polymer chains.
A New Hydrocarbon Elastomer. I. Copolymerization of Olefins and Nonconjugated Dienes
Authors: Gladding E. K. , Fisher B. S. , Collette J. W. 
Published: February 2011

Abstract
The composition of sulfur-curable elastomers derived from olefins and diolefins is described and methods are given for their synthesis using coordination catalysts. Certain factors that influence the laboratory-scale polymer synthesis are discussed and the effects of catalyst type, polymerization temperature, and diene structure on the rate of polymer formation and polymer composition are outlined. Polymer properties are discussed in general terms, with particular emphasis on oxidative stability.
A New Hydrocarbon Elastomer. II. Properties of an Ethylene-Propylene-Nonconjugated Diene Terpolymer
Authors: Verbanc J. J. , Fawcett M. S. , Goldberg E. J. 
Published: February 2011

Abstract
A new hydrocarbon elastomer has been synthesized from petrochemical intermediates using coordination catalysis. This amorphous polymer resembles commercial diene elastomers in general appearance, is completely soluble in hydrocarbon and chlorinated hydrocarbon solvents, and is stable to prolonged storage. It can be vulcanized effectively by the use of accelerated sulfur systems and reinforced by numerous fillers such as carbon blacks, clays, and certain silicas. Reinforced vulcanizates are strong, resilient, and extremely resistant to oxygen, ozone, heat, light, and many chemical agents. Properly compounded vulcanizates exhibit excellent electrical and low temperature properties. Permeability to gases, specifically nitrogen, oxygen, and carbon dioxide, parallels natural rubber. Thermal diffusivity and thermal conductivity are ∼15% greater than polyisoprene. The practical significance of the thermal data remains to be determined.
A New Hydrocarbon Elastomer. III. Compounding with Fillers and Plasticizers
Authors: Schoenbeck M. A. 
Published: February 2011

Abstract
Nordel can be compounded with a wide variety of fillers. Reinforcing carbon blacks and silicas are required for maximum physical properties. Non-reinforcing fillers may be added to the compounds to reduce material costs. As with other elastomers, vulcanizates containing mineral fillers have lower states of cure. One of the outstanding characteristics of Nordel is its extendability. Compounds with large amounts of carbon black and oil are easily processed and have good vulcanizate properties. Hot masterbatching in the presence of promoters significantly improves processing safety, modulus, resilience, compression set, and electrical properties of mineral-filled stocks. Petroleum oils, including aromatic types, are excellent plasticizers for Nordel. Those containing low amounts of nitrogen bases and unsaturates, as indicated by the Rostler method of analysis, are preferred especially in low sulfur recipes designed for maximum heat resistance. The properties of Nordel vulcanizates suggest its use in extruded goods, hose, belts, coated fabrics, molded goods, sponge, heels and soles, wire insulation and jacketing, and tires.
Reactions of Polymers in Bulk. V. Deformation Behavior of Vulcanizates Filled with Inorganic Fillers
Authors: Janacek J. 
Published: February 2011

Abstract
The most marked difference between carbon black and the fillers of inorganic nature is the difference in effect on the interlinking reactions taking place in the rubber. It is shown that the deformation properties of vulcanizates filled with inorganic substances depend upon the same physical characteristics that describe the behavior of carbon black, if the influence of the difference in chemical activity of the fillers is discounted.
Reactions of Polymers in Bulk. VI. Influence of Deformation on the Decrease of Crosslinking Density
Authors: Jánaček J. 
Published: February 2011

Abstract
The influence of deformation on the decrease of the degree of crosslinking as determined by swelling was investigated in vulcanizates which were filled with various concentrations of carbon black and which were crosslinked to different degrees, as well as the stress relaxation of these vulcanizates after deformation to a constant elongation. The decrease of crosslink density depends on the amount of deformation, is directly proportional to the degree of crosslinking of the undeformed rubber, and increases with the specific surface and with the carbon black concentration. Vulcanizates in which the degree of crosslinking has been reduced by deformation, behave like vulcanizates which were crosslinked to a lesser degree by the vulcanization system.