bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vulcanization of Crepe Rubber by Sulfur Monochloride. II. The Dilatometric Method
Authors: Glazer J. 
Published: February 2011

Abstract
The vulcanization of rubber by sulfur monochloride is believed to consist of the cross-linking of adjacent isoprene units by thio-ether bonds. Such a reaction, involving polymer aggregation, should be accompanied by an increase of the density of the rubber, and, by choosing a suitably delicate technique, it should be possible to measure the rate of vulcanization by observing density changes. A dilatometric method seemed most suitable, and it was found that the reaction could indeed be followed by observing the rate of decrease of volume of the system rubber-sulfur monochloride when dissolved in a suitable solvent. Initial experiments showed that, during cold vulcanization, the system underwent a volume contraction which was of the order of 10 per cent with respect to the rubber. This comparatively large contraction allowed one to work with extremely dilute solutions (&lt;0.3% w/w) of rubber. It thereby became possible to study the systems under more ideal kinetic conditions of high dilution than has been hitherto possible. In the present investigation, it has not been possible to do more than establish the broad outlines of the kinetic behavior of the system, and, on this basis, to propose feasible mechanisms for the cold vulcanization process.
The Curing of Silicone Rubber with Benzoyl Peroxide
Authors: Bueche A. M. 
Published: February 2011

Abstract
Little has been reported about the action of benzoyl peroxide as a vulcanizing agent for silicone rubber. Knowledge of this action seems to be of consider- able importance, since benzoyl peroxide is the most widely used vulcanizing agent at the present time. Apparently no studies of the kinetics of peroxide decomposition in silicones have been undertaken. It is not known quantitatively whether or not the silicones influence the decomposition rate in the way some of the solvents studied by Cass and by Nozaki and Bartlett do. In this paper we report the results of work undertaken to determine the number of cross-links introduced into polydimethylsiloxane by benzoyl peroxide during the normal vulcanizing process. The apparent efficiency of cross-link production has been determined as a function of the concentration of peroxide, the method of vulcanization, and of the filler content of the sample.
Structure and Dielectric Properties of Rubber Mlxtures Containing Carbon Black
Authors: Dogadkin B. , Lukomskaya A. 
Published: February 2011

Abstract
One of the fundamental steps in solving the problem of the reinforcement of rubber is that of explaining the nature of the reaction between rubber and fillers. The measurement of heat effects during swelling, in addition to presenting experimental difficulties, does not provide a direct evaluation of the intensity of the rubber-filler bond in rubbers used in industry. In order to measure this bond, the present authors studied the frequency and temperature relations of the dielectric constant ε′ and the tangent of the angle of dielectric losses, tan δ, of unvulcanized natural rubber and sodium-butadiene rubber, rubber-carbon black mixtures, and vulcanized rubber containing different loadings of channel and furnace blacks. The measurements were made in the frequency range of 50 to 2.5×107 cycles per second at 20° C and also in the frequency range of 103 to 4×104 cycles per second at temperatures from −75° to 152° C. As the experiments show (see Figure 1), the coefficient of dielectric loss, ε″=ε′⋅ tan δ, of a raw rubber has no maximum within the frequency range and temperature range studied. At the same time, the rubber-carbon black mixtures are characterized by a maximum ε″ at frequencies of (2−2.5)×103 cycles per second, which depends to a slight extent on the temperature. Vulcanizates containing no carbon black have a maximum ε″ at (2−3.5)×106 cycles per second at 20° C, which is displaced to the temperature range −24° to −27° when the frequency is decreased to 103 cycles per second. Both maxima are observed on the ε″ curves with loaded vulcanizates, the first caused by the heterogeneity of the rubber-carbon black mixture, and the second due to the formation of sulfur dipoles during vulcanization. Consequently, the ε′ curves have two regions of change.
Promoters for the Reaction of Rubber with Carbon Black
Authors: Doak Kenneth W. , Ganzhorn George H. , Barton Bernard C. 
Published: February 2011

Abstract
Heating unvulcanized mixtures of rubber and carbon black gives increased electrical resistivity, reduced hysteresis and hardness, higher modulus, and increased abrasion resistance to the vulcanizate. This is believed to result from improved dispersion of carbon black, accompanying a chemical reaction between rubber and carbon black. Butyl rubber, with low unsaturation, reacts more slowly than Hevea rubber or butadiene-styrene copolymers (GR-S). Chemical promoters decrease the time and temperature required for the reaction. Certain quinones and aromatic nitroso compounds are effective in both Hevea and Butyl rubber. t-Butyl perbenzoate and cumene hydroperoxide are particularly effective in Hevea rubber and GR-S containing channel black, and when used in optimum amounts, do not adversely affect tensile strength. Hexachlorocyclopentadiene and hexachlorophenol are effective in both Hevea and Butyl rubber, l,3-Dichloro-5,5-dimethylhydantoin and hexachlorocyclopentadiene are effective in Butyl containing channel or furnace blacks. Chemical promoters are believed to initiate allylic or alkyl radicals on rubber chains, which react with active centers on carbon black, forming primary valence bonds.
Structure and Rheological Properties of Hevea Latex Gels
Authors: De Vries A. J. , Van den Tempel M. 
Published: February 2011

Abstract
Some rheological properties of hydrogels made from Hevea latex have been determined by shear measurements, using a hollow cylindrical test piece. The shear modulus and the viscosity depend on the volume concentration of solids in the gel, the composition of the interfacial layer surrounding the rubber globules, and the particle-size distribution of the rubber globules. An interpretation of the experimental results is given, based on the assumption that no coalescence of the rubber particles occurs. The rheological properties of the gel should then be functions of the number of points of contact between the particles and of the strength of the bonds between the particles in the gel.
Abrasion and Slippage
Authors: Ebert G. , Weidner V. 
Published: February 2011

Abstract
The types of apparatus used technically for testing the abrasion resistance of rubber compounds, in particular tread compounds, have been equipped to operate with 100 per cent slippage. The results obtained under such conditions seldom agree with the results of road tests, because the abrasion of tires under ordinary conditions takes place with relatively little slippage. No method for determining abrasion which takes this fact into account has yet come to the attention of the authors. Although the present work is already rather old, its publication still seems justified, since it focusses attention on some still unpublished results which are essential to any estimation of the practical behavior of tread compounds when subjected to abrasion.
A Study of Some Heat-Sensitizing Agents for Hevea Latex
Authors: Pariente Claude 
Published: February 2011

Abstract
Latex mixtures containing different heat-sensitizing agents were studied from five points of view: conditions of gelation, changes of viscosity, changes of mechanical stability, heat sensitization (with and without zinc oxide), and the physical properties of the vulcanizates. It would seem that conventional heat-sensitizing agents can be replaced to advantage by agents such as triacetin or nitroparaffins, which more nearly approach the ideal agent as defined at the beginning of this work. In addition, triacetin gives latex mixtures which are particularly easy to process. As for the nitroparaffins, they are noteworthy for giving vulcanizates with excellent mechanical properties.
The Accelerated Coagulation of Latex
Authors: Van Gils G. E. , Resing W. L. 
Published: February 2011

Abstract
The object of the study described in this paper has been a very practical one. However, the results from a practical point of view are rather disappointing, mainly because of economic reasons, but we think them interesting enough to have them published, because some light may be thrown on our basic knowledge of the coagulation phenomena of Hevea latex.
Zinc Oxide Testing of Latex
Authors: Madge E. W. , Collier H. M. , Newnham J. L. M. 
Published: February 2011

Abstract
Viscosity changes in concentrated natural rubber latex under different experimental conditions were investigated with the object of determining the mechanism of zinc oxide thickening and to find reasons for inconsistencies in correlating results of the zinc oxide thickening or ZOT test with other latex tests. It has been found that small variations of the amount of naturally occurring soap are of great importance in the thickening of latex containing zinc oxide, especially at the low ammonia content used for the ZOT test. The effect of added soap on the ZOT test was found to vary from latex to latex and to be different for different soaps. Less than about 0.3 per cent of various soaps added to latex prior to the zinc oxide reduced the degree and rate of thickening. With more than this amount of soap, the thickening depended on the soap used. A similar investigation in which the mechanical stability of latexes containing varying amounts of added soap and a standard amount of zinc oxide was measured, showed that the latexes varied anomalously with the amount and the type of soap added. The results of the work presented in this paper show that new tests for the zinc sensitivity of latexes must take into account a number of hitherto unsuspected factors, particularly when such tests are required to have a bearing on processing behavior.
Butyl-Type Polymers Containing Bromine
Authors: Morrissey R. T. 
Published: February 2011

Abstract
Butyl rubber has been modified by attaching bromine to the polymer chain. The reaction has been considered as mainly one of addition to the double bonds, thereby lowering the unsaturation. Both sulfur and metal oxide can serve as vulcanizing agents for brominated Butyl, and both may function in the same compound, thus producing a faster rate of cure compared to Butyl. Brominated Butyl can also be covulcanized with natural rubber and GR-S, and therefore it is now possible to impart to these rubbers the excellent properties of Butyl, such as low air diffusion and resistance to ozone and flex-cracking. Still other advantages compared to Butyl rubber are higher modulus and good adhesion to other elastomers and metals. Data have been presented to show that the properties of these new Butyl-type polymers can be varied by the amount of bromine which they contain. It has also been shown that there is an optimum range of the halogen concentration required for obtaining the best properties both in mixtures with natural rubber and in brominated Butyl polymers used as adhesives. This optimum range of bromine also depends on the original unsaturation of the polymer.
Study of the Reaction Kinetics of Aging of Natural Rubber by Infrared Spectrography IV. Influence of Wave Length of Light and Temperature on Light Aging
Authors: Tkáč A. , Kellö V. , Hrivíková J. 
Published: February 2011

Abstract
The influence of the wave length of radiation on the process of photocatalytic aging of rubber, as well as the relations between the intensity of radiation and the temperature, were studied by infrared spectroscopy. The upper limit of effectiveness of light lies in the range of 4360 A˚. While an increase of temperature greatly accelerates oxidation, an increase of radiation intensity retards it. Numerous analyses reveal an exponential relation between the length of the induction period and the intensity of radiation at constant temperature, and a linear relation between the height of the experimental curves and the temperature at constant intensity. Oxidation destruction and side-chain formation (vulcanization) take place simultaneously during the aging of natural ruber. The relation between these reactions depends on the experimental conditions ; the temperature accelerates oxidation, while the intensity of radiation aids vulcanization.
Viscoelastic Properties of Linear Polymers in the High-Elastic State
Authors: Vinogradov G. V. , Dzyura E. A. , Malkin A. Ya , Grechanovskii V. A. 
Published: February 2011

Abstract
The relation between molecular weight, chain rigidity, and the length of the high-elasticity plateau is determined from frequency and temperature dependences of the storage modulus for polybutadienes and polystyrenes with Mw/Mn≤1.1. Use is made of the concept of equivalence of high-elastic states characterized by equal lengths of high-elastic plateaus for linear polymers. The high-elastic states of the linear polymers studied are equivalent if the polymer chains have equal numbers of dynamic segments and if the reference temperature is T0=1.22Tg, where Tg is the glass transition temperature. The viscoelastic properties of the polymers in the high-elastic state are determined unambiguously by Tg and the molecular weight of the dynamic segment. The quantitative relation between thermomechanical characteristics obtained by measuring deformation versus temperature under a constant time regime and dependence of storage modulus versus frequency under isothermal conditions is discussed.
Influence of Hysteresis on Tensile and Fatigue Failure in Rubbers
Authors: Payne A. R. , Whittaker R. E. 
Published: February 2011

Abstract
The failure criterion developed by Harwood et al. between energy input to break and hysteresis at break for amorphous rubbers has been related to the fatigue and cut growth properties of the rubber which are based on the tearing energy theory. It is found that the constant K in the hysteresis failure criterion is a function of the cut growth constant G and the inherent flaw size C0. The effect of adding fine particulate fillers to amorphous rubbers on the hysteresis and fatigue properties is considered and shown to be in agreement with the theory.
The Actual Contact Area and Friction Properties of Elastomers under Frictional Contact with Solid Surfaces
Authors: Bartenev G. M. , Lavrentjev V. V. , Konstantinova N. A. 
Published: February 2011

Abstract
Using a specially designed apparatus simultaneous measurements were carried out of the area of contact and the friction between elastomers and solid surfaces. For a wide range of load, the friction force is proportional to the actual contact area and the friction constant depends only on the nature of the rubbing solids. In the range of low sliding velocities the actual contact area remains almost constant. At high sliding velocities increase of the friction force is associated with the process of the mechanical glass-transition of the surface layer of the crosslinked rubber which causes the actual contact area to decrease.
Modulus of Plasticized Ionic Rubbers
Authors: Eisenberg A. , King M. 
Published: February 2011

Abstract
The rubbery modulus of a crosslinked ionizable rubber is explored in the absence of the crosslinking effect of ions, that is, only through the effect of ions on conformation. The crosslinking effect is eliminated by plasticizing the rubber with a liquid of high dielectric constant. Experimentally, a rubber is prepared by mixing poly (acrylic acid) and poly (vinyl alcohol) and cross-linking thermally. The relationship between the rubbery moduli of the unionized and the ionized forms of the plasticized material is studied. A theory for the modulus of such a two-component rubber is derived and the predictions are compared with experiment. It is shown that the predicted ratio of the moduli in the acidic and ionic forms is in the same direction as determined experimentally, but that the calculation underestimates the magnitude of the effect. Several reasons for this discrepancy are given.
Heat Schedules in the Vulcanization of Thick-Walled Articles
Authors: Sverdel M. I. , Aronovich F. D. 
Published: February 2011

Abstract
The analytical relationships obtained make it possible to determine the equivalent time and duration of vulcanization of thick-walled rubber articles with constant temperatures on the heating surface without complete calculation of the temperature field. The method is suitable for a preliminary selection and assessment of schedules of vulcanization of covers in shaper-vulcanizers.
The Growth of One-Dimensional Shock Waves in Elastic Nonconductors
Authors: Chen Peter J. , Gurtin Morton E. 
Published: February 2011

Abstract
In this paper we study the propagation of shock waves in elastic materials that do not conduct heat. We derive a differential equation relating the strain and strain gradient behind the wave when the region ahead is unstrained and at constant entropy. Using this equation we are able to give conditions under which the wave will grow or decay at a given time. Generally, the results are qualitatively the same as in the purely mechanical theory.
Hysteretic Losses in Rolling Tires
Authors: Willett P. R. 
Published: February 2011

Abstract
A relationship between the observed energy losses for a tire that has reached a state of thermal equilibrium when operating at a constant speed, and the viscoelastic properties of the tire components has been formulated. The analysis was carried out by systematically varying tire components and operating parameters, using the Vibron Viscoelastometer and tire test wheel dynamometer. The investigation was carried out for 6.95–14 cross ply passenger tires. From the derived dependence of the tire energy losses on viscoelastic properties, the effect of changes in tire tread compound, ply rubber and tire cord on the tire energy losses can be predicted. This enables the design of a tire with the properties to meet desired service characteristics.
The Determination of Network Chain Density and the Chemical Stress Relaxation of Crosslinked Polymers
Authors: Tamura Saburo , Murakami Kenkichi 
Published: February 2011

Abstract
Both initial network chain densities nM(0) and nS(0) of dicumyl peroxide- cured natural rubbers were determined from the tensile stress and swelling method, respectively. The difference between nM(0) and nS(0) was usually constant, independent of the magnitude of network chain density. That is, it was found that the number of entanglement network chains in the crosslinked natural rubber was usually constant, independent of network chain density. The entanglement network chain density nII(0) was 0.7×10−4 mole/cc. This led to the supposition that the molecular weight between entanglement points Me would be about 9000. Although this value is far from exact, it does not differ too greatly from the value found for noncrosslinked natural rubber. Next, in order to calculate the number of main-chain scissions of crosslinked polymers from their chemical stress relaxation, we proposed our modification of Tobolsky's equation. Using our equation, it was found that the scission of dicumyl peroxide-cured natural rubber occurred in the main chain only. Furthermore, this value agreed with the one obtained from the oxidation of toluene solution of noncrosslinked rubber under the same conditions.
Prevulcanization Inhibitor of Sulfur-Free Thiuram Vulcanization
Authors: Ducháček Vratislav 
Published: February 2011

Abstract
On the basis of Mooney scorch measurements at 120° C and of continuous measurements of vulcanization in a Vuremo curemeter at 145° C, sulfenamides which function as inhibitors of the sulfur-free thiuram vulcanization have been investigated. It was found that the actual prevulcanization inhibitor is 2-mercaptobenzothiazole. Its formation from sulfenamides is activated by zinc dimethyldithiocarbamate since the vulcanization of rubber by thiuram disulfides in the presence of zinc oxide is always accompanied by the formation of zinc dithiocarbamate. It seems probable that the inhibition effect of 2-mercaptobenzothiazole is attributable to the formation of a complex with zinc dimethyldithiocarbamate which decreases the reaction rate in the initial steps of the sulfur-free thiuram vulcanization and thus causes the scorch delay.
Effect of the Degree of Dispersion of the Curing System on the Properties of Rubber Compounds and Vulcanizates
Authors: Fedyukin D. L. , Vinogradova T. I. , Danchenko L. A. , Ermilova N. V. 
Published: February 2011

Abstract
The viscosity of a rubber compound and its curing rate are determined by the number of initial aggregates of rubber mobilized around the ingredients of the curing system and by the distances between them. The lower the degree of dispersion of the ingredients of the curing system, the later is the cure stage in which a continuous vulcanization network is formed.
Mechanical Behavior of O-Rings
Authors: Curro J. G. , Salazar E. A. 
Published: February 2011

Abstract
O-ring deformation is approximated as a plane strain contact problem. An integral equation is written for the contact stress which is solved for small deflections. The contact area agrees with the results of the conventional Hertz theory. The displacements of the deformed o-ring are found by requiring zero displacement at the center of the circular cross section. Experimental results on silicone rubber cylinders and o-rings agree with the theory up to approximately 15 per cent strain. A linear viscoelastic solution is constructed from the elastic solution for an o-ring held at fixed deflection for t &gt; 0. For this case the contact area remains constant and the average load is proportional to the relaxation modulus.
Viscoelastic Properties of Truck Tire Compounds and the Related Heat Build-Up
Authors: Kainradl P. , Kaufmann G. 
Published: February 2011

Abstract
Rubber compounds used in the manufacture of tread-cap, tread-base, and for the rubber-coating of the rayon cord for 12.00–20 tires have been varied in composition and, in consequence, their viscoelastic properties have been altered. Operating temperatures, in test-wheel runs, have been measured in the shoulder region of the tire close to the casing, using a needle-thermocouple. Multiple-regression has been used to investigate which combinations of viscoelastic properties of the rubber vulcanizates would give a linear, significant correlation to the heat build-up in the tire with a minimum residual. From the nature of the variables in the regression functions, conclusions have been drawn on the type of load occurring in the different components of the tire. It was found that the tread cap contributed to the heat build-up according to its loss compliance E″/|E*|2 and the carcass according to its loss-factor, E″/E′. Thus, the statistics show that the greater contribution to the heat build-up comes from the tread-base, according to its loss-factor also. The values of temperatures, calculated by the multiple-regression, show deviations of only a few degrees centigrade compared to the average temperatures of tires of the same construction. Therefore the operating temperatures of tires to be expected as a result of the compound variations can be estimated in advance. On individual tires greater deviations, up to 10°C, have been measured. These are due to inevitable inaccuracies in tire building and errors in temperature measurements.