bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of the Temperature upon the Durability of Rubber in Corrosion Cracking
Authors: Zuev Yu S. , Borshchevskaya A. Z. , Pravednikova S. I. , Yue-Jin U. 
Published: February 2011

Abstract
1. The rate of reaction of an undeformed rubber stock with a reactive medium is determined by the diffusion, while the rate of destruction of a deformed stock is determined by its chemical interaction with the medium. 2. The magnitude of the apparent activation energy (u) of the rupture of a stock in the presence of a reactive medium does not undergo perceptible alteration in the range of deformations 30 to 80%, while on transition to deformations of 500 to 700% the values of the apparent activation energy increase. 3. The temperature coefficient of rupture depends upon the nature of the bonds being destroyed and upon the capacity of the reactive medium for adsorption on the stock. On rupture in the gaseous phase the apparent activation energy has a lower value than on rupture in a solution of the same agent. 4. In a wide range of deformations the time to rupture of stocks obeys a complex system of laws, passing through a minimum value in the region of the critical deformation, εcrit. The position of εcrit depends upon the temperature, type of ‘aggressor’ (i.e. reactive agent) and physical state of the medium (gas, solution). 5. As a result of the shift of εcrit with alteration in temperature there is possible the phenomenon of anomalous dependences for certain deformations, i.e., the time to rupture at low temperatures are less than for higher temperatures with identical deformations and concentrations of the medium.
Metal Halides in Vinylpyridine Rubber (PBR)
Authors: Brucksch W. F. 
Published: February 2011

Abstract
It has been found that PBR is made stronger by the addition of certain metal halides. A kind of cross-linking results, probably by coordination of pyridine nitrogens. This crosslinking can be used as a supplement to that produced by curing with sulfur. The result is improved physical properties in vulcanized products. Gum stocks show higher tensile strength. Filled stocks show higher tensile strength and elongation at 100° C and greater resistance to abrasion and to cut-growth. The system also has the capacity to develop high modulus. Because of this, lesser amounts of filler may be used. The result is a compound which has hysteresis properties like a carcass stock and abrasion resistance like a tread stock. This is an interesting combination of properties, which should fine useful applications.
Chlorobutyl Rubber—Optimum Processing Procedures
Authors: Ziarnik G. J. 
Published: February 2011

Abstract
Chlorinated butyl rubber cures faster, forms more stable crosslinks, and provides wider compounding versatility than conventional butyl rubbers. Because of chlorobutyl's increased reactivity MgO is added to control scorch. Unfortunately, MgO also retards development of stress-strain properties in cured vulcanizates. While these effects can be explained on the basis of an interference with the vulcanization process, data indicate that MgO retards polymer-pigment interaction as well. Heat treating has been shown to reduce the retarding influence of MgO without sacrificing processing safety. Cure systems respond differently to heat treatment, some showing little or unfavorable effects. Heat treating is effective only with vulcanization systems that crosslink through unsaturation rather than through bis-alkylation reactions involving chlorine. A mechanism is proposed which explains these phenomena in terms of a competition for available chlorine between polymer-polymer crosslinking and polymer-carbon black interaction which together contribute to the final crosslinked network. Processing safety is maintained because of a reaction between MgO and a small fraction of tertiary-allylic chlorine which is believed to contribute to scorch. In processing chlorobutyl compounds, therefore, whenever MgO is used to control scorch safety, heat treatment is desirable in order to reduce the retarding influence on vulcanization and reinforcement. Heat treating is effective, however, only in compounds cured with vulcanization systems capable of crosslinking through unsaturation. Since HCl may be a byproduct of thermal reactions, heat treatment should not be carried at temperatures above 330° F unless a suitable acid scavenger such as MgO, PbO, or CaSiO3 is employed. When such materials are present in the compound, temperatures up to 400° F can be tolerated. Optimum processing procedures for chlorobutyl compounds will depend on the requirements of a given application, the cure system required, and the limitations of available processing equipment.
The Chemistry of Vulcanization. IX. Accelerating Mechanism of 2-Aminothiobenzothiazole
Authors: Fukuda Haruko , Tsurugi Jitsuo 
Published: February 2011

Abstract
2-Aminobenzothiazole, i.e., 2-aminobenzothiazolylaulfenamide, MSNH2 was used as a model of the commercial sulfenamide type accelerators. Behavior of MSNH2 was studied in diphenylmethane, DPM, which served as a hydrocarbon containing α-methylenic hydrogen. MSNH2 decomposes in DPM at 140–160° to give MS· and ·NH2 together with a minor amount of free sulfur radical. This suggests homolytic dissociation of the S—N bond as well as the C—S bond of MSNH2, though the latter bond dissociates in minor degree. Dissociation of both bonds makes the reaction sequence complicated. When sulfur was added to the MSNH— DPM system, the radical MS· (or M·) opens the sulfur ring to accelerate the reaction of DPM with sulfur. The presence of sulfur results in the less complicated reaction products. The activating mechanism of zinc butyrate in the reaction involving MSNH2, sulfur and DPM is the same as that involving thiazole type accelerators. However, the zinc salt of MBT which is produced from MSNH2 and zinc butyrate interacts with the radical ·NH2, giving an intermediate 2-amino-benzothiazole, MNH2. The latter reacts with zinc butyrate to give N-(2-benzo-thiazolyl) butyramide, RCONHM. Evolution of ammonia was observed even in the presence of sulfur and zinc butyrate.
The Chemistry of Vulcanization. X. Accelerating Mechanism of Sulfenamide Type Accelerators
Authors: Fukuda Haruko , Tsurugi Jitsuo 
Published: February 2011

Abstract
The mechanism of acceleration of the commercial sulfenamide MSNR2 (NR2 denotes cyclohexylamino or morpholino and M denotes 2-benzothiazolyl) was studied by using diphenylmethane (DPM) as a model of rubber hydrocarbon. Since amine (NHR2) liberated from MSNR2 complicated the reaction, the results obtained here were compared and correlated with those using the simple sulfenamide MSNH2. The preceding paper reported that ammonia evolved from MSNH2 did not disturb the reaction. The reaction mechanism of MSNR2 in DPM both in the presence and absence of sulfur appear to be the same as those of MSNH2 respectively, though difficulties of the identification and determination of the products did not permit a clear-cut conclusion. In the DPM-sulfur-MSNR2-zinc butyrate system, MBT produced from sulfenamide via 2-benzothiazolylsulfenyl radical interacts with zinc butyrate to give zinc salt of MBT (MSZnSM). This compound, on the one hand, suffers induced decomposition by sulfur to give benzothiazolyl-sulfenyl radical again, and on the other hand, interacts with the radical ·NR2 to yield MNR2. The delayed action of MSNR2 was interpreted by induced decomposition only by ⋅Sx⋅ as compared with that of MSZnSM both by S8 and ⋅Sx⋅. The accelerating entity of the sulfenamide is the 2-benzothiazolylsulfenyl radical, which splits the S8 ring molecule, as in the case of other thiazole type accelerators. However, amine librated from the sulfenamide also is considered to accelerate the vulcanization.
Determination of Free Sulfur in Stocks Cured with Sulfur Containing Accelerators
Authors: Khehaskova E. P. , Okhapkina N. A. , Provorov V. N. 
Published: February 2011

Abstract
For the determination of free sulfur in vulcanized rubber the normal method is the sulfite method, consisting of the heating of a sample of rubber with a solution of sodium sulfite. The free sulfur reacts with the sulfite, forming thiosulfate, which is determined by iodometric titration. The unreacted excess of sulfite is removed with formalin. The method gives good results in the analysis of stocks which do not contain sulfur-containing accelerators. In the presence of these accelerators the results are high: in some cases the method is quite inapplicable, as it is impossible to establish the endpoint of titration accurately. This may be explained by the circumstance that the accelerators and the products of their decomposition during vulcanization can pass into the solution of sodium sulfite and react further with the iodine. The method of determination of free sulfur proposed by Hardmann, consisting of the acetone extraction of the rubber in the presence of copper gauze, is protracted and complicated. A certain improvement in the sulfite method of Bolotnikov and Gurova was introduced in the ASTM method (1952). Sodium stearate is added to the sodium sulfite solution for better wetting of the rubber, and a certain amount of paraffin to prevent the formation of foam. After termination of heating the solution the stearic acid is precipitated with strontium nitrate and certain accelerators with cadmium acetate. For the majority of stocks this method gives correct results, but in a number of cases it is difficult to establish the end of titration at all.
The Mechanism of Optimum Vulcanization in Some Synthetic Rubbers
Authors: Gavrishchuk V. Ya , Zubov P. I. 
Published: February 2011

Abstract
1. We investigated the tensile strength and types of sulfur in vulcanizates prepared from butyl rubber and neoprene. 2. It became evident that optimum vulcanization in these vulcanizates is caused by the disintegration of intramolecular polysulfides.
Dependence of Bound Rubber on Concentration of Filler and on Temperature. I
Authors: Dessewffy Oliver 
Published: February 2011

Abstract
The change in quantity of rubber gel with the concentration of carbon black in filled natural rubber compounds was studied. It was established that there is a linear relationship between the amount of rubber gel and the black concentration, within a range of 20 to 80 parts of black to 100 parts by weight of rubber. No clear-cut relation exists between the quantities of rubber gel or the constants for the linear relations and the physicomechanical properties of the vulcanizates. The factors upon which the amount of bound rubber depend, i.e., the degree of degradation of the rubber, the heat treatment of the mixtures and the extraction temperature, do not alter the linear character of the cited relation. The critical concentration of certain types of blacks was determined. Up to this concentration no coherent rubber/black gel system is formed. The critical values for the black concentration are clearly related to some of the elastic properties of the filled vulcanizate.
cis-trans-Isomerization of 1,4-Polybutadiene under the Influence of Nitrogen Dioxide
Authors: Ermakova I. I. , Dolgoplosk B. A. , Kropacheva E. N. 
Published: February 2011

Abstract
It is well known that, under the influence of various catalytic agents of ionic nature, cis-trans isomerization of natural rubber takes place. Sulfur dioxide, organic aluminum compounds, titanium halides, anhydrous hydrogen chloride and other materials show similar action. Also established is the possible isomerization of cis forms of natural rubber at elevated temperatures, under the influence of selenium, thio acids and a number of compounds which are dissociated through a radical mechanism, an example being benzoyl disulfide. For cis-1,4-polybutadiene, the possibility of isomerization by means of ultraviolet rays and also by means of gamma radiation, in the presence of sensitizers has been demonstrated. This is also accomplished by means of thio acids and several organic sulfides. As may be surmised, isomerization takes place under conditions dependent on consecutive reactions involving addition of free radicals to the double bonds and the dissociation of the products thus formed:
Diisocyanate-Linked Polymers. III. Relationships between the Composition and Ultimate Tensile Properties of Some Polyurethane Elastomers
Authors: Smith Thor L. , Magnusson Alan B. 
Published: February 2011

Abstract
The tensile strength and elongation at rupture of elastomers vary markedly with the experimental conditions used in measurement. For example, when measured at a fixed rate of extension, the tensile strength may increase by a factor of 100 or more as the temperature is decreased, and the ultimate elongation may increase concomitantly by a factor of 10 or more and then decrease to a few per cent. The ultimate properties also depend on the chemical nature of the network chains, the degree of crosslinking, and on the regularity of spacing of the crosslinking sites. In addition, those elastomers which crystallize during extension (e.g., vulcanized natural rubber) normally exhibit higher tensile strengths and ultimate elongations than those which do not crystallize (e.g., SBR rubbers). In seeking relationships between the structure and the ultimate properties of elastomers, these various factors which affect ultimate properties must be carefully considered. Previously a study was made of the tensile strength and ultimate elongation of several series of polyether-polyurethan elastomers prepared from polyoxypropylene glycol 2025 (PPG), trimethylolpropane (TMP), and either toluene 2,4-diisocyanate (TDI) or hexamethylene 1,6-diisocyanate (HDI). The structure of these elastomers was characterized by (1) the number of network chains per unit volume ν and (2) the concentration of urethan groups [U]. These parameters could be varied independently over certain ranges by making appropriate changes in the average molecular weight of PPG 2025 through blending it with dipropylene glycol (DPG). The glass temperature Tg of the elastomers increased linearly with [U], the rate of increase being considerably greater for the TDI-linked than for the HDI-linked elastomers. These elastomers apparently did not crystallize upon extension, and their ultimate properties, measured at a fixed extension rate, were found to depend on both [U] and ν. However, when compared in corresponding temperature states, i.e., at equal values of T−Tg, the ultimate properties over a wide temperature range were found to be independent of [U], or approximately so, when [U] was less than about 1.85 moles/kg. Also, the ultimate elongation was observed to be inversely proportional to ν, although the proportionality constant was temperature-dependent. It thus appears that certain elastomers which do not crystallize have ultimate properties which depend not only on ν and Tg but also on the chemical nature of the network chains.
The Temperature Shift of the Second Order Transition of Natural Rubber by Crosslinking
Authors: Heinze H. D. , Schmieder K. , Schnell Gg , Wolf K. A. 
Published: February 2011

Abstract
The present article reports on dynamic mechanical and infrared spectroscopic tests of natural rubber crosslinked by sulfur, peroxide or high energy radiation. The effect of these vulcanization methods upon the rate of crosslinking, the position of the second order transition temperature and the double bond structure is discussed. Whereas the temperature displacement of the transition range from the second order transition phase to the rubber elastic state during crosslinking by high energy radiation or by peroxide arises from the increasing hindrance of chain movement by the crosslinks, the intramolecular addition of sulfur predominantly is responsible for the much greater temperature displacement—related to the same crosslink density—during sulfur vulcanization. The change of the double bonds which proceeds in the sulfur vulcanization at a much faster rate than in the crosslinking by irradiation also can be considered as indication of intramolecular rings being formed along the chain during sulfur vulcanization. Vulcanization by sulfur and crosslinking by irradiation appear, principally, to be based on the same mechanism. The influence of oxidation on the mechanical properties of the vulcanizates is studied in natural rubber irradiated in an oxygen atmosphere. The two damping maxima observed at the dynamic mechanical test can be ascribed, with the aid of infrared spectroscopy, to the influence of crosslinks and oxidation products on the chain mobility.
Kinetic Interpretation of Rheological Behavior of High Polymers
Authors: Furukawa Junji 
Published: February 2011

Abstract
Rheological behavior of high polymers is interpreted in terms of the pseudo crosslinking hypothesis, i.e., polar groups in a polymer form a kind of pseudolink and contribute to the elastic property of the polymer, but such a crossbond as this is not so firm that plastic flow may not occur to some extent. The ratio of real elongation of polymer chain to overall elongation of specimen is demonstrated as the function of slippage of the polymer chain. Creep and stress relaxation are accounted for as the phenomena involving slippage of the chain accompanied by the elongation of the chain and the dissociation of the crossbond. The stress-strain relation in the ease of constant rate drawing is supposed to show the existence of maximum stress according to the hypothesis. Rupture of linear high polymer is also discussed supposing the breakdown of the second crossbond and the breakdown may be concluded when load applied is larger than the maximum value estimated from the equation for the equilibrium crosslinking. The rate of rupture is also discussed and the logarithmic life time in rupture is concluded to be correlated linearly to the load applied.
A Study of Synthetic Rubber Latexes by the Electron Microscope
Authors: Rupar W. , Mitchell J. M. 
Published: February 2011

Abstract
In emulsion polymerization the number and size of the latex particles govern not only the colloidal behavior of the reacting system but also the rate at which conversion of the monomer progresses. Because of the importance of these factors a wide variety of synthetic latexes have been studied with the electron microscope. The changes in the latex particles—from swollen monomer-polymer particles at low conversion to the final latex particles after removal of the unreacted monomer—have been observed for a typical SBR system. The effects of various post polymerization treatments on the size and size distribution of the latex particles have also been observed.
Elastomer Structure and Adhesion. II. Effect of Sidechain Double Bonds
Authors: Raevskii V. G. , Voyutskii S. S. , Livanova I. V. 
Published: February 2011

Abstract
1. A study was made of elastomers of the effect of double bonds in the side groups, which are capable of adding sulfur, on the variation of the strength of adhesion to fiber-forming polymers during vulcanization. 2. It is shown that the presence of such vinyl groups does not measure the general nature of the dependence of the variation of the strength of adhesion on the degree of vulcanization previously found for elastomers which do not contain vinyl side groups. However, an increase in the content of 1–2 units leads to a drop in the maximum degree of crosslinking (increase in the values of Mc, max) and to a drop in the speed of decrease of this strength after the attainment of optimum adhesion. 3. The experimental data were examined from the point of view of the diffusion theory of adhesion and complete agreement with this theory is shown.
Bonding of Polyethylene to Metals and Rubber with Hydrogenated Polybutadiene
Authors: Yakubchik A. I. , Grilikhes S. Ya , Tikhomirov B. I. , Purlova V. S. 
Published: February 2011

Abstract
The adhesive composition based on hydrogenated unbranched 1,4-polybutadiene gives a high bond strength between polyethylene and brass, and brass-plated metal, and rubber.
Hydrogenation of Natural and Synthetic cis-1,4-Polyisoprene
Authors: Yakubchik A. I. , Tichomirov B. I. , Sulimov V. S. 
Published: February 2011

Abstract
1. Hydrogenation of natural and synthetic cis-1,4-polyisoprene has been accomplished. Polymers of lower molecular weights are more easily hydrogenated. 2. Hydrogenation of cis-1,4-polyisoprene at temperatures of 80–140° are not followed by cis-trans isomerization and apparently is not accompanied by cyclization. 3. The polymers have higher glass temperatures as the degree of hydrogenation is increased.
Polymerization of Butadiene with Alkylaluminum and Cobalt Chloride
Authors: Gippin Morris 
Published: February 2011

Abstract
The diethylaluminum chloride combination with cobaltous chloride or cobaltous chloride pyridinates requires water in a certain mole ratio to the diethylaluminum chloride to activate them as catalysts for butadiene polymerization at 5° C to 98% cis-1,4 structure. The cobalt-pyridine complex is the preferred component because of its ability to function in trace amounts. Several organic derivatives of water failed as substitutes. However, aluminum trichloride is effective as a substitute for water on an equimolar basis. The cis-1,4 content in the polymer decreases at higher polymerization temperatures. The higher pyridinates of cobaltous chloride tend to reduce the polymer molecular weight within narrow limits. The preferred solvent is benzene, in which the concentration of the monomer is a factor in both microstructure and polymer molecular weight. Certain mixtures of benzene and hexane provide another means of controlling molecular weight. The rate of polymerization is linear with respect to time in the initial stages, and is a first-order reaction with respect to monomer at a fixed concentration of catalyst.
Ethylene-Propylene Rubber Vulcanization with Aralkyl Peroxide and Coagents
Authors: Robinson A. R. , Marra J. V. , Amberg L. O. 
Published: February 2011

Abstract
Ethylene-propylene rubber (EPR) has been described in terms of its performance characteristics both by Prof. Natta and by the authors, who concur basically on its merits. Before such evaluations were possible, however, a difficult vulcanization problem was faced. The same paraffin inertness which is advantageous in the vulcanized product ruled out most of the conventional vulcanization technology. Work on the vulcanization problem at Hercules indicates that, with few promising alternatives, aralkyl and alkyl peroxides provide the best practical solution. This paper presents some conclusions and interpretations based on the exploratory work at Hercules on the EPR vulcanization process with dicumyl peroxide. The supporting evidence is derived mainly from crosslink density analysis by the solvent swelling method of Kraus. Special use was made of a “per cent gel” factor and of analysis of the sol fraction of incompletely cured vulcanizates. The copolymers described were prepared in Hercules laboratories.
Ethylene-Propylene Copolymers Produced with Soluble Catalysts
Authors: Kelly R. J. , Garner H. K. , Haxo H. E. , Bingham W. R. 
Published: February 2011

Abstract
Soluble catalyst systems derived from alkyl aluminum halides in combination with vanadium oxytrichloride or tetrachloride produce highly random ethylene-propylene copolymers with high catalyst efficiency. By the choice of the alkyl aluminum halide and molar ratio of aluminum to vanadium, variations in polymerization efficiency and molecular weight are possible. The copolymers prepared with these soluble catalysts show advantages in both processing and physical properties over those prepared with heterogeneous catalysts. Vulcanizates of these copolymers show somewhat different accelerated aging properties depending on the additive used along with the peroxide. Low temperature properties of copolymers containing less than 70 weight % propylene show a tendency for crystallization which is not shown by X-ray diffraction. Overall physical properties and tire tests show some preference for the 65 weight % propylene copolymer over the 50% material.