bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gel Formation in the Mastication of Natural Rubber, and Its Influence on Vulcanizate Strength
Authors: Dogadkin B. A. , Kuleznev V. N. 
Published: February 2011

Abstract
Angier and Watson observed formation of spatial structures (gels) in neoprene rubber, certain SBR fractions, and butadiene-acrylonitrile rubber, under the influence of powerful shearing forces during treatment in a specially designed scroll-type masticator. This gel formation was considered to be a specific characteristic of synthetic rubbers ; no one has reported gel formation in the mastication of natural rubber (NR). In our experiments an insoluble gel was formed in NR. Weighed samples of extracted smoked sheet were masticated in an argon atmosphere containing not more than 0.05% oxygen, on specially designed rolls, with 0.12 mm gap between the rolls cooled intensive with water. The formation of an insoluble fraction (gel) at the early stages of mastication was established in repeated experiments. Its maximum content (after 10 minutes of mastication) reaches 20%, and further milling results in mechanical dispersion of the gel fraction, so that after 60 minutes of mastication the rubber is again completely soluble in the common solvents. However, the masticated rubber contains formations branched to such an extent that most of them (∼80%) are precipitated from octane solution by centrifugation at 12,000 rpm for an hour. Molecular weight determinations, based on changes in the light scattering of the solutions at an angle of 90°, showed that the molecular weights of the sol fractions of the masticated samples increase during mastication, reaching 2,500,000 after 60 minutes. The true molecular weight of the particles is apparently of major significance, as a correction for the asymmetry of the scattering particles was not applied.
Macroradicals in the Mechanical Degradation of Polymers in the Glassy State
Authors: Butyagin P. Yu , Berlin A. A. , Kalmanson A. E. , Blyumenfeld L. A. 
Published: February 2011

Abstract
By means of the method of electron paramagnetic resonance a demonstration is given of the occurrence of macroradicals during the degradation of glassy polymers whether of organic (polystyrene, polyethylene, polymethyl methacrylate) or of inorganic (quartz) nature.
Production and Properties of Block Polymers
Authors: Kovarskaya B. M. , Golubenkova L. M. , Akutin M. S. , Levantovskaya I. I. 
Published: February 2011

Abstract
1. In special apparatus (a laboratory modifier and a continuous modifier) block polymers are produced from condensation resins and various starting polymers by a mcchanochemical method. 2. It is demonstrated that the physicochemical properties of the resulting block polymers differ essentially from the properties of a mechanical mixture of homopolymers, which makes it possible to produce polymers with new properties.
Friction Studies on Rubberlike Materials
Authors: Conant F. S. , Liska J. W. 
Published: February 2011

Abstract
One of the best summaries of the theory of friction between solid materials up to 1949 was published by Bowden and Tabor. However, little attention was devoted in this review to either theoretical or experimental results on the friction between rubberlike materials and other solids. In recent years, the literature on various aspects of the friction of rubberlike materials has become quite voluminous and unfortunately sometimes contradictory in the results and interpretations presented. This is understandable, to some extent, in the light of the fact that each individual research effort has usually been directed toward some particular aspect of the problem; certain, sometimes rather arbitrary, conditions are employed or assumed, and the results obtained are often rather unclear functions of these experimental or theoretical parameters. The situation is further complicated by the facts that at the very best, experimental frictional studies do not yield very accurate or readily reproducible data and the theories proposed, in many cases, are not subject to exact experimental verification. No comprehensive effort has been made, to date, to unify the various theories and to reconcile the conflicting experimental results on the friction of rubberlike materials and it is not the principal objective of the present review to do so. One of the aims is rather to report and summarize these sometimes divergent views in the hope that investigators in this field will be encouraged to study those areas in which knowledge is either inconclusive, contradictory or incomplete. Generally speaking, dynamic friction can be defined as the tangential reaction between two solids in relative motion in the presence of a normal force between the two solids. This definition can include both sliding and rolling friction. This review will be concerned principally with the sliding friction phase since rolling friction is generally conceded to be explained almost entirely by the internal friction of the deformable material. It has been stated, for example, that the rolling resistance of pneumatic tires at 80–95 mph is composed of 90–95% internal hysteresis, 2–10% surface friction and 1.5–3.5% air friction.
Elastomeric Adhesion and Adhesives
Authors: Weidner C. L. , Crocker G. J. 
Published: February 2011

Abstract
An increasing number of papers in the field of adhesion have been appearing in Rubber Chemistry & Technology. In the period 1941–1950 twenty-two papers appeared in this Journal covering various aspects of adhesion, whereas in the year 1959 alone eleven papers appear. The Rubber Division Library at the University of Akron has compiled bibliographies as follows: Bibliography # 10, “Use of Synthetic Resins in Natural and Synthetic Rubbers”, covering the period 1930–1952; Bibliography # 18, “Rubber to Metal Bonding”, in two parts, one covering the period 1937–1954 and a supplement covering 1955–1958; and Bibliography #20, “Reclaim Rubber Cements”, covering the period 1927–1954. In addition, special bibliographies were prepared covering the period 1949–1958 on the subjects “Rubber to Wood Adhesives”, “Rubber to Fabric Adhesives”, “Bonding of Polyurethanes”, “Metal to Metal Adhesives”, and “Chemistry of Rubber Adhesives”. The most comprehensive text in the field is “Adhesion and Adhesives” edited by N. A. DeBruyne and R. Houwink. More limited in scope are “Adhesive Bonding of Metals” by Epstein, “Adhesives for Wood” by Knight, “Adhesive Bonding of Reinforced Plastics” by Perry. Also “Rubber to Metal Bonding” by Buchan, which stresses the brass plating technic. Skeist has recently edited a “Handbook of Adhesives”. The Encyclopedia of Chemical Technology contains articles on “Adhesives” in Volume I and the First Supplement Volume. Various symposia have been sources of worthwhile papers on adhesion. The Division of Paint, Plastics, and Printing Ink Chemistry, ACS, published such papers in their preprint booklets, volume XV, No. 1 (1955) and volume XX, No. 1 (1960). Papers given at this division's “Recent Advances in Adhesives” symposium in 1957 are also published. Publication of papers at two symposia held in 1952 (Society of The Chemical Industry, London; Case Institute of Technology, Cleveland) form a valuable collection. Papers from The Second International Congress of Surface Activity in London in 1957 are also published. Papers from a Symposium on Adhesion held by the Society of Rheology in 1959 are published in volume IV of the Society's Transactions. General review articles on adhesion with extensive bibliographies were published as follows : Rinker-Kline “Survey of Adhesives and Adhesion; Kline-Reinhart “Fundamentals of Adhesion”; Brantley-Charnell “Investigation of the Nature of Forces of Adhesion”; Reinhart-Callomon “Survey of Adhesion and Adhesives” and Rutzler “Types of Bonds Involved in Adhesion”. The Reinhart-Callomon survey is quite extensive in its bibliography.
Ionizing Radiation and Elastomers
Authors: Gehman S. D. , Gregson T. C. 
Published: February 2011

Abstract
The phenomena which are observed in investigations concerned with high energy ionizing radiation and elastomers follow generally from the principles of related fields such as the interactions of radiation with matter; radiation, polymer, and polymerization chemistry ; and the molecular structure of elastomers in relation to their physical properties. The way in which the knowledge from these various fields is integrated to account for the results with elastomers gives a specialized aspect to the interpretations, which however is very much the same for elastomers as for polymers in general. As usual, the modifying circumstance is the generally greater sensitivity of the physical properties of elastomers to changes in structure than is the case for ordinary polymers. In sketching the relatively short history of work with intense, high energy radiation and elastomers, it is not possible to ignore the unusual circumstances under which it has progressed. The Atomic Energy Act of 1946 transferred control of atomic energy from military to civilian agencies. But it retained such a tight government monopoly in the field that there was little incentive for independent research looking toward peaceful applications from the military developments. However, the Oak Ridge National Laboratory did begin the distribution of isotopes under a licensing system in 1947 which provided opportunities for a broader acquaintance with the characteristics of isotopic sources of radiation and techniques for handling them although the levels were, as a rule, quite low. The Atomic Energy Act of 1954 encouraged a much more liberal participation of private enterprise in the atomic energy program. After the passage of this Act many segments of industry became actively interested in exploring the significance of the new knowledge and technologies for their operations.
Ski Rubber, a New Polyisoprene
Authors: Subbotin S. A. , Samoletova V. V. , Znamenskaya A. K. 
Published: February 2011

Abstract
It is known that the industrial synthesis of general purpose rubbers has been accomplished and has been developing on the basis of the use of divinyl as the starting monomer, taken either in the pure state (sodium-divinyl rubber) or in mixture with another monomer—styrene (divinylstyrene rubber). However, synthetic polymers of isoprene have, to this day, found no practical application despite the fact that natural rubber (NR) is a polyisoprene and the first samples of synthetic rubber were obtained from isoprene. This is explained by the circumstance that, up to the present time, it was not possible to synthesize an isoprene or a copolymer-isoprene rubber which would have substantially improved properties over a similar rubber obtained on the base of divinyl; in addition isoprene is a less plentiful raw material than divinyl. Divinyl rubbers differ from natural rubber not only in their microstructure but also in the chemical nature of the link of the polymer chain; and still, with time, they successfully replaced natural rubber in the production of a large number of rubber goods. At the same time, due to various new properties possessed by the divinyl rubbers, their application led to the improvement in the quality of certain goods and, in many cases, to a simplification and reduction in cost of production of the latter. Nevertheless even the most modern general purpose commercial rubbers, which are obtained from divinyl, possess various substantial shortcomings in comparison with natural rubber. The most significant shortcoming of the divinyl rubbers is their reduced elasticity. This shortcoming is especially significant all the more, since rubber mixes with these rubbers as a base must, because of their low strength, be prepared with a large content of carbon black. For this reason such rubbers cannot serve as an equivalent substitute for natural rubber in carcass and breaker rubbers for tires, especially truck tires, and in the manufacture of various technical and also household, highly elastic goods.
Crosslinking of Oriented Rubber
Authors: Charlesby A. , von Arnim E. 
Published: February 2011

Abstract
Smoked sheet rubber, previously oriented in the calendering process, was crosslinked by exposure to 2 Mev high energy electrons in the absence of vulcanizing agents. Even after annealing, the resultant rubber showed anisotropic elastic properties, having a high elastic modulus and a low elongation at break in the direction of orientation. It is suggested that radiation in addition to crosslinking causes main chain fracture and stress relaxation in stressed molecular chains. The G value for crosslinking (1.05) by electron irradiation agrees well with that (1.1) previously found by elastic measurements of pile irradiated rubber.
Adduct Rubbers: A Versatile New Family of Elastomers
Authors: Pierson R. M. , Gibbs W. E. , Meyer G. E. , Naples F. J. , Saltman W. M. , Schrock R. W. , Tewksbury L. B. , Trick G. S. 
Published: February 2011

Abstract
A versatile family of elastomers has been prepared by free radical addition of aliphatic mercaptans to the double bonds of diene polymers. High saturation levels were readily achieved without degradation of the basic polymer chain. The technology is similar to ordinary emulsion polymerization. By varying the nature of the base polymer, the mercaptan used, and the extent of saturation, a wide range of compositions and of physical properties were attained in the adducts. In general, resistance to aging, ozone attack, heat, solvent swelling, and to permeation by gases increased with increasing extent of saturation. Outstanding performance in these qualities was achieved by adducts of polymers whose double bonds had been over 90 per cent saturated. A highly saturated methyl mercaptan adduct of polybutadiene showed (1) stress-strain and air aging properties at 400° and 500° F better than commercially available ethylacrylate copolymers and various semicommercial heat resistant elastomers; (2) permeability resistance equivalent to butyl; (3) solvent swell intermediate between neoprene and medium nitrile content butadiene-acrylonitrile rubbers, with a Tg below −30° C; (4) ozone resistance comparable to the better commercially available saturated rubbers. Increased solvent resistance was obtained by preparing adducts of the appropriate butadiene-acrylonitrile copolymers. Adducts with saturation levels up to about 85 per cent could be cured by the same procedures used for the base polymers. Activated or butyl-type curing systems were required for higher saturation levels. The relative rates at which aliphatic mercaptans add to the several types of double bonds present in emulsion diene polymers have been examined in a preliminary way.
The Oxidative Softening of Synthetic Rubber Latex
Authors: Herte P. 
Published: February 2011

Abstract
A method is described for plasticizing Buna S3 when still as a latex. A plasticization of Buna S3 to the Buna S4 stage is carried out in the presence of metal sols or alkyl phenols, and through use of air or oxygen-enriched air. Softening takes place under low gage pressure, at temperatures around 100° C, and at rates that are technically feasible. In contrast to Buna S4 that has been produced soft by means of polymerization control, the Buna S4 obtained through this softening process has certain advantages, e.g., higher elasticity values in heavily-loaded compounds. So-called recovery can be retarded by careful dosing with phenyl-2-napththylamine. The introduction of this process into the synthetic rubber industry, using continuous latex breakdown in a countercurrent reaction tube, is discussed.
Reactions of Free Radicals in Solution. V. Destruction of Polymeric Molecules by Free Radicals
Authors: Bresler S. E. , Dolgoplosk B. A. , Krol V. A. , Frenkel S. Ya 
Published: February 2011

Abstract
1. It was established that free radicals produce degradation of polymer chains. 2. Ideas were put forward on the possible mechanism of the reaction leading to the breaking of a carbon-carbon bond in polymer molecules.
The Vulcanization of Elastomers. 16. The Vulcanization of Natural Rubber with Sulfur in the Presence of Dithiocarbamates (I)
Authors: Scheele Walter , Birghan Klaus 
Published: February 2011

Abstract
The kinetics of vulcanization of natural rubber with sulfur (initial concentration: 1 mole S8 in 10 kilograms of mixture) was investigated in the presence of varying amounts of zinc diethyldithiocarbamate (ZnDEDC). The following results were obtained. 1. At all temperatures and, depending upon the dithiocarbamate content of the mixture, over practically the entire, or at least the greater, extent of vulcanization, sulfur decrease is a zero order process. 2. The rate of sulfur decrease is, as long as it proceeds according to zero order, independent of the molar ratio S8:ZnDEDC. From the slope of the log rate versus 1/T plot is derived an activation energy of 29.2 kcal. 3. During vulcanization the dithiocarbamate content declines as long as the sulfur decrease follows the zero order. With decreasing starting content of dithiocarbamate, the stock finally uses up all the zinc dithiocarbamate during vulcanization. In other cases, a constant limiting value of dithiocarbamate decrease appears. 4. When zinc dithiocarbamate and zinc oxide are both present, sulfur decrease again takes place according to zero order. Under these conditions the process will use up less dithiocarbamate and shortly after the onset of vulcanization a constant final value of dithiocarbamate appears. 5. After the initial lag, crosslinking, measured by reciprocal equilibrium swell in benzene, proceeds according to zero order over the major extent of vulcanization. The temperature function of relative rates of crosslinking furnishes an activation energy similar to that for the rate of sulfur decrease. 6. Reciprocal equilibrium swell deviates from zero order time dependence as soon as the dithiocarbamate decrease reaches its final value, and the sulfur decrease also experiences a considerable lag. 7. It is shown that the limiting value of equilibrium swell increases as the starting content of dithiocarbamate decreases and also that reversion sets in at higher temperatures. When the molar ratio of mixing S8:ZnDEDC amounts to 1 or to 0.5, the limiting value of the swelling index is reached independent of temperature, i.e., the degrees of crosslinking are the same for these two ratios. The investigations will be continued.
The Vulcanization of Elastomers. 17. The Role of the Oxide in Vulcanization with Thiuram Compounds. II
Authors: Scheele Walter , Grasemann Horst , Mau Günter 
Published: February 2011

Abstract
The reaction of tetraethylthiuram disulfide with zinc oxide, in which significant amounts of zinc dithiocarbamate are formed, was investigated quantitatively. The decrease in thiuram disulfide and increase in dithiocarbamate were followed by conductometric titration with HCl (dithiocarbamate) and with CuSO4 in the presence of hydroquinone (thiuram disulfide) as well as by a spectrophotometric method. Both methods gave as the limiting value for the dithiocarbamate formation, 90 mole %, calculated on the initial thiuram disulfide. This value is independent of the reaction temperature. Judging from this evidence on dithiocarbamate formation, it seems clear that some condition holds here other than that which holds in the case of a thiuram vulcanization. In the latter case, the limiting value for dithiocarbamate formed, also independent of temperature, is 66 mole % based on the initial thiuram disulfide. In incompletely reacted mixtures of ZnO and thiuram disulfide, the spectrophotometric method indicates higher dithiocarbamate content than does the conductometric method of analysis. This shows that spectrophotometry shows at least one (unknown) compound which conductometry does not detect. The spectrophotometric analyses of thiuram vulcanizates are in agreement with the results of conductometric titrations of the vulcanizate extracts; both methods indicate 66 mole % as being the limiting value for dithiocarbamate formation; likewise, the same kinetic relations are found by the two methods. The use of the spectrophotometric method was carefully checked with control tests.
The Radioactive Tracing of the Diffusion of Sulfur in Cable Rubbers
Authors: Blokh G. A. , Korniltseva Z. P. , Olshanskaya L. A. , Kolobenin V. N. 
Published: February 2011

Abstract
The use of radioactive isotopes is a progressive and promising innovation in the study of the manufacture of cable rubber. Thus, in an earlier article the authors demonstrated the possibility of using the radioactive isotope of sulfur, S35, in the study of diffusion processes in cable rubbers during vulcanization. The use of labelled sulfur as the vulcanizing agent in core rubber mixtures has shown: (1) an intensive diffusion of sulfur from the core rubber mixture into the insulating rubber during vulcanization; (2) the presence of a high concentration of accelerators in a thin (0.1 mm) surface layer of the insulating rubber ; this is a fundamental cause of the overcure of the insulating rubber, which leads to the appearance of cracks, accelerated aging, and other defects; (3) an intensive exchange of sulfur atoms among the accelerators and between them and the bound polysulfide sulfur. Thus, as a result of the diffusion of sulfur from the core mixture to the insulating rubber, the nature of the sulfur bonds is changed, and a number of polysulfide structures are formed. It has been shown that the polysulfide-bound sulfur is mobile, that is, it takes part not only in the isotopic exchange of sulfur atoms, but also in the diffusion process. According to Bresler, the coefficients of diffusion of free polysulfide sulfur can be calculated from measurements of the radioactivity.
Tension Flaws in Bonded Cylinders of Soft Rubber
Authors: Gent A. N. , Lindley P. B. 
Published: February 2011

Abstract
It is not uncommon to subject rubber-to-metal bonded components to tensile loads lower than that required to break a well-bonded unit as a routine check of the bonding efficacy. We have observed that internal fractures occur in soft vulcanized natural rubber cylinders bonded to metal endpieces when subjected to comparatively low tensile loads. Such internal flaws may well pass undetected, but their presence might be expected to impair the strength, service behavior and life. No previous account of their occurrence is known to us. The rubber mixes used contained little or no carbon black, and gave vulcanizates having hardnesses in the range 30–45° British Standard. The test-pieces, in the form of cylinders 2 cm in diameter and 0.07–0.50 cm in height, were prepared by a molding process and bonded by means of cements (‘Ty Ply’ UP and RC) to metal endpieces during vulcanization. Load-deflection relations in tension were determined using a Hounsfield tensometer, the deflection being imposed at a speed of 0.16 cm/min.