bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Mutual Solubility of Polymers. II. The Viscosity of Mixed Rubbers and the Behavior of Solutions of These
Authors: Slonimskiĭ G. L. , Komskaya N. F. 
Published: February 2011

Abstract
1. Mixtures of rubbers and raw rubber stocks prepared from a combination of two rubbers possess anomalous properties in a number of cases, revealed in the appearance of a maximum in the curve of the viscosity of such a system in relation to the proportions of the rubbers. 2. A mixture of solutions of different rubbers equal in concentration in a common solvent separates into two phases in the majority of cases, thus demonstrating the limited mutual solubility of the rubbers. This separation does not take place if the solutions are dilute enough so that the molecules of the two solvents enter into practically no reaction with one another. For a given pair of polymers, the minimum concentration at which the separation still takes place depends on the nature of the solvent. 3. In agreement with present-day theoretical opinion on the solubility of polymers, the results obtained demonstrate the decisive part played by interactions between the chain molecules, i.e., by the heat of mixing; and the insignificant part played by changes of entropy in the process of mutual solution of two polymers possessing chain molecules of equal size and flexibility. 4. The study of mixed polymer solutions is a valuable source of information on the mutual solubility of polymers. The experimentation carried out on rubber solutions confirms the mutual insolubility of a number of pairs of rubbers which was observed earlier in the study of the mechanical properties of vulcanizates prepared from mixed rubbers.
The Mutual Solubility of Polymers. III. Heats of Mixing of Polymers
Authors: Struminskiĭ G. V. , Slonimskiĭ G. L. 
Published: February 2011

Abstract
1. Measurements of the heats of mixing as between different polymers, which we have carried out, have confirmed the correctness of the assumption that the heat effect plays a decisive part in the process of mutual mixing of polymers. 2. The anomalous behavior of mixtures of SKS-30 with SKB and polystyrene with SKB has been revealed. 3. Experimental data on the heats of mixing of polymers, which has substantial value for theoretical and practical research in the field of polymer mixtures and for the evaluation of possible practical applications of these, has been collected.
The Mutual Solubility of Polymers. IV. The Effect of the Packing Density of Polymer Molecules on Their Mutual Solubility
Authors: Slonimskiĭ G. L. , Struminskiĭ G. V. 
Published: February 2011

Abstract
1. It is pointed out that the decrease in volume plays an important part in the mixing of polybutadiene rubber (SKB) with butadiene-styrene rubber (SKS-30) and of polybutadiene rubber with polystyrene. In this connection it is emphasized that the assumption of volumes being additive in the mixing of polymers is limited in application. 2. It was shown that the heat effects of the mixing of polymers does not depend on the degree of polymerization, provided that no contraction takes place in mixing, and that the sign of the heat effects can even be changed if the packing of the molecule becomes more loose as the degree of polymerization increases. 3. From a theoretical analysis of experimental data found in the literature the opinion was advanced that the critical mixing temperatures for the systems polybutadiene rubber-butadiene-styrene rubber and of polybutadiene rubber-polystyrene are low, being somewhat above the vitrification temperature of polystyrene. The existence of lower critical mixing temperatures here is caused by a decreased packing density in the molecules of polystyrene and of butadiene-styrene rubber at temperatures below the vitrification temperature of polystyrene.
The Heat Aging of Natural Rubber Vulcanized with Tetramethylthiuram Disulfide
Authors: Fletcher W. P. , Fogg S. G. 
Published: February 2011

Abstract
Acetone extraction of the TMTD stock, which is known to remove the ZnDMDC formed during vulcanization, also leads to a reduction in heat aging resistance. Addition to the extracted vulcanizate of the appropriate quantity of ZnDMDC from a solution improves the aging behavior although not to the level of the untreated vulcanizate. This failure to restore in full the aging resistance of the initial stock by swelling in the appropriate quantity of ZnDMDC is hardly surprising since it is likely that the ZnDMDC will be present in the original and in the dosed vulcanizate in somewhat different physical forms and distributions. The results demonstrate that the dithiocarbamate formed in situ during TMTD vulcanization plays a major part in conferring heat resistance to such vulcanizates.
The Mechanism of Accelerator Action. Reaction of Mercaptobenzothiazole with Sulfur
Authors: Dogadkin B. , Tutorskiĭ I. 
Published: February 2011

Abstract
The investigation of the reaction of sulfur with mercaptobenzothiazole (MBT) is of great interest from the point of view of clarifying the mechanism of the action of the latter as a vulcanization accelerator. We studied the reaction of MBT with elemental sulfur in the melt and in solvent media—vaseline oil and xylene. The course of the reaction was followed by means of the H2S liberated, which was removed from the reaction medium by a continuous stream of nitrogen and was absorbed in a solution of CdCl2. In Figure 1 are presented the kinetics of the liberation of H2S on heating the mixture in a medium of vaseline oil, the concentration of MBT and sulfur comprising, respectively, 0.06 mole/liter and 0.655 g-atom/liter. This ratio and concentration of reactants corresponds to those in the vulcanization of rubber. As can be seen, the splitting out of H2S under the stated conditions proceeds at a constant rate, which can be explained by the very insignificant change in concentrations of reactants over the entire time (only 1.5% of the MBT introduced reacted in 10 hours at 140°). The kinetics of the liberation of H2S from a melt of MBT and sulfur at 140° practically coincide with the kinetics of the reaction in solution (see Figure 1). The temperature dependence of the rate constants leads to the expression K=3.54⋅1010e33500/RT.
Role of Hydrogen Disulfide in Vulcanization
Authors: Tinyakova E. I. , Khrennikova E. K. , Dolgoplosk B. A. 
Published: February 2011

Abstract
It was shown that the breakdown of hydrogen disulfide in α-olefins results in the exclusive formation of addition products (mono-, di-, and tetrasulfides) without formation of hydrogen sulfide and free sulfur. Similar results were obtained when sulfur reacted with monoethanolamine (vulcanization accelerator) in α-olefin solution.
The Theory of Rubber Reinforcement: Interaction of Carbon Black with Sulfur and Rubber
Authors: Dogadkin B. , Lukin B. , Tarasova Z. , Skorodumova Z. , Tutorskiĭ I. 
Published: February 2011

Abstract
Active channel black combines chemically with sulfur when heated with sulfur solutions. The amount of sulfur combined increases after hydrogenation of the carbon black. The dimensions of the carbon black aggregates increase as the result of the reaction with sulfur. Hydrogenation of channel black increases the content of insoluble rubber in the carbon-rubber gel formed during milling of a rubber-carbon black mixture. Hydrogenation of channel black increases the content of bound sulfur, the modulus, and tensile strength, in comparison with vulcanizates containing the original unhydrogenated channel black. These facts suggest that active carbon black enters the composition of the vulcanizate structure, and this is a factor in rubber reinforcement.
Bound Rubber and Mechanical Properties of Diene Polymers
Authors: Palinchak S. T. , McSweeney E. E. , Mueller W. J. , Stickney P. B. 
Published: February 2011

Abstract
1. Tensile strength is apparently a function of the particle size of the pigment and how well it is dispersed in a polymer. 2. Modulus and abrasion resistance are apparently functions of the interaction of the pigment and the polymer. This cannot be attributed entirely to bound-rubber formation, since bound rubber may occur without reinforcement, as shown by the results with silica pigment. 3. Results of processing studies show that Philblack O has a stabilizing effect on the polymer during processing and more consistent and better properties are obtained if processing is performed with carbon black present at temperatures below those for gel formation. This effect is more pronounced for less stable polymers such as polybutadiene. 4. Philblack O slows down gel formation. 5. It is possible that silica may have a destabilizing effect on polybutadiene unless it is buffered with agents such as resins, stearic acids, and diethylene glycol.
Correlation between Laboratory Abrasion and Road Testing
Authors: Prat C. 
Published: February 2011

Abstract
In a preceding article, we expressed the hypothesis that probably no discontinuity exists between abrasion testing on the road and that on laboratory machines. The latter showed the peculiarity of being characterized by its very high severity. Let us recall briefly that the severity is expressed by the absolute wear of a reference mixture during the test considered. We were able to verify the existence of a relationship independent of the type of testing carried out, but a function of the severity of the tests, between the wear of an experimental mixture and a reference mixture. This relation manifests itself in different types of mixtures in the form of regressing lines. These are shown in Figure 1 where we have used logarithmic coordinates. The correlation coefficients calculated for different regressions are in the neighborhood of 0.93 to 0.95 and consequently very highly significant. The interpretation and use of the curves shown on the graph necessitates, however, a few remarks of importance: Firstly, it must be noted that each of the lines corresponds to a particular standard of comparison. Each of them is independent of the others. for example, for that labelled “Rubber-Resin A”, the comparison rests on the wear of this type of combination rubber-resin as a function of the wear of the mixture (natural rubber containing 28 volumes of HAF black) having served as a reference for the tests, while for the line labelled “Rubber + SAF black”, the reference mixture is a natural rubber containing 28 volumes of MPC black. It will not be necessary then, in any case to compare the curve for “Rubber-SAF Black” to that for “Rubber-Resin A”.
Load-Deflection Relations and Surface Strain Distributions for Flat Rubber Pads
Authors: Gent A. N. 
Published: February 2011

Abstract
Rubber components comprising flat pads of vulcanized rubber secured between rigid flat surfaces are widely used as mountings and couplings. They are subjected to compression or shear, or a combination of both deformations, often of relatively large magnitude. The shear deformation is produced by the displacement of one rigid bounding surface in its own plane with respect to the other. It differs from a homogeneous shear deformation if the pad thickness is comparable with the dimensions of the cross-section, when an appreciable bending component enters into the total deflection. The corresponding load-deflection relations have been examined by Rivlin and Saunders. The compression deformation differs from a state of pure homogeneous compression in that the rubber adheres or is bonded to the rigid compressing faces and sliding at the interface is precluded. The rubber therefore bulges laterally as the deflection is imposed. The loaded surfaces are subjected to a uniform displacement, while the free surface of the pad is subjected to known stresses (zero). The resulting mixed boundary value problem has not proved tractable even for classically small displacements—its solution for large elastic displacements does not appear imminent. This problem has therefore been treated experimentally. Since the preparation of the paper, an approximate theoretical treatment has been developed. It is described in the APPENDIX. for any rubber component the presence in use of excessive local surface strains is undesirable and a longer service life may be anticipated if the geometrical design of the surface is such that high concentrations of strain do not arise. In principle it should be possible to derive the state of strain at the surface by mathematical analysis, but in practice the problem is difficult and conclusions can only be drawn in some restricted cases. Simple measuring techniques are described whereby the distribution of strain over the surface of a rubber component may be examined experimentally. These methods have been used to determine the regime of strain over the free surfaces of some bonded rubber cylinders subjected to overall compression and extension.
The Structure of Cyclized Polybutadiene
Authors: Shelton J. Reid , Lee Lieng-huang 
Published: February 2011

Abstract
Polybutadiene was cyclized with sulfuric acid under rather drastic conditions. The cyclization was confirmed by the decrease of unsaturation and the change of physical properties. The low degree of unsaturation of cyclized polybutadiene, as determined by the iodine-bromide method, suggested the formation of polycyclic structures. Oxidation of cyclized polybutadiene with acidic permanganate gave a dibasic acid, C16H22O4, which corresponds to a tricyclic ring system. Consequently, the structure of cyclized polybutadiene may be considered to include polycyclic structures joined by uncyclized segments of the molecular chain together with isolated six-membered rings. Further study will be necessary to fully establish the structure of cyclized polybutadiene.
Aeration of Natural Rubber Latex. II. Graft Polymerization of Vinyl Monomers with Aerated Latex Rubber
Authors: Sekhar B. C. 
Published: February 2011

Abstract
The peroxidic groups produced on the rubber hydrocarbon when oxygen is absorbed by ammonia-preserved latex are capable of initiating the graft polymerization of methyl methacrylate and other vinyl monomers, in the presence of suitable reducing agents. The products so formed contain only small proportions of unbound homopolymer. In the latex state, the products have a much higher wet gel strength and better film forming properties than materials of the same total vinyl polymer content prepared by other methods.
Melting and Glass Transitions in Polyisobutylene
Authors: Kell R. M. , Bennett Bailey , Stickney P. B. 
Published: February 2011

Abstract
The purpose of this work was to investigate the crystallization behavior of uncompounded, unstressed polyisobutylene and butyl rubber. Glass transition data obtained during the work are also reported. The data were determined dilatometrically. The work was prompted by a literature survey which collected transition data on elastomers. It was found that crystallization information for polyisobutylene and butyl rubber was based largely on x-ray studies of these polymers under high elongation. In fact, it has been assumed generally that these polymers would crystallize only when highly oriented, as by stretching. Because of the resistance of polyisobutylene to ordering when in the unstressed state, no measurements of optimum crystallization temperature or melting temperature, Tm, have previously been reported. Information of this type is important because of its bearing on the mechanical behavior of a polymer. Many types of elastomers will crystallize readily if oriented by a large stress. However, only those having relatively simple structures crystallize readily under zero stress. Such behavior is, of course, a limiting factor in low-temperature serviceability. Polyisobutylene might seem at first to have the required simplicity of structure; however, steric hindrance of the side methyl group forces the chain to crystallize in a helical configuration having a molecular repeat distance of 18.6 A, as shown by Fuller, Frosch, and Pape. This is the greatest repeat distance of any of the elastomers, suggesting that a lengthy exposure period would be required if ordering were to occur at all. A clue to ordering in an isobutylene copolymer was furnished by Gehman, Woodford, and Wilkinson, who reported that a butyl tread stock showed a greatly increased torsional stiffness after storage for about 40 days at −30° C. The aged butyl sample exhibited an x-ray diffraction pattern suggestive of crystallization. These results may be the first showing crystallization in a butyl polymer essentially free of stress. In other work, Radi and Britt, using equilibrium temperature-retraction techniques with samples elongated 300 per cent initially, found that two types of butyl polymers showed optimum crystallization rates at −30° and −41° C. The aggregate of these results suggests that crystallization might occur in unstressed polyisobutylene if sufficient time were allowed, and indicates an optimum rate in the range of −30° to −40° C. This is reasonable by comparison with natural rubber, which has a glass transition temperature very close to that of butyl rubber, and an optimum crystallization rate at about −25°C.
Carbon-Black Loaded Rubber Vulcanizates: Volume Changes in Stretching
Authors: Mullins L. , Tobin N. R. 
Published: February 2011

Abstract
The changes in volume which occur during the stretching of carbon black reinforced vulcanizates have been measured, and the results used to examine crystallization which accompanies the extension of natural rubber. The effect of previous extension on these changes is interpreted in terms of a simple model previously advanced by the authors to describe the stress-strain properties of reinforced vulcanizates.
Efficiency of TMTD Vulcanization
Authors: Bevilacqua E. M. 
Published: February 2011

Abstract
Tetramethylthiuram disulfide (TMTD), together with a sufficient amount of zinc oxide, is the simplest and most efficient vulcanizing agent known for introduction of sulfur crosslinks into rubber. No other combination approaches it in efficiency over a wide range of temperatures, although under limited conditions sulfur cures can be obtained with approximately as high a crosslink density per mole of vulcanizing agent. The stoichiometry of vulcanization with this curative has been explored in some detail in recent work of Scheele and coworkers. They have confirmed the observation by Jarrijon that during vulcanization dithiocarbamate is formed equivalent to close to two-thirds of the TMTD taken. The generality of this result was established in an exhaustive series of experiments, covering a range of structures of thiuram disulfide and of polyolefin, of temperature, and of concentration of reactants.
Equivalent Cures in Specimens of Various Shapes
Authors: Conant F. S. , Svetlik J. F. , Juve A. E. 
Published: February 2011

Abstract
A procedure has been developed for adjusting the curing times and state of cure of rubber products of various shapes and thicknesses to be equivalent to that obtained with a standard tensile sheet at some specified time and temperature. A nomograph has been constructed which permits the calculation of the lag or incubation time involved in curing articles of varying shapes and compositions. If the incubation time is found to be longer than the tensile sheet cure, a correction is applied. This correction is obtained from a curve relating the ratios of tensile sheet cure time and incubation time to product cure time and incubation time. Another nomograph was constructed for transposing cure times at one temperature to those at a different temperature. It was constructed on the basis that in the 280° F range the rate of cure is doubled for an 18° F increase in temperature. This procedure for adjusting the curing times of products to be equivalent to that of the standard tensile sheet is demonstrated. Suggested test methods are given for determining the state of cure in a product as compared with the state of cure in a tensile sheet when given the “best” or most desirable cure. These methods included determination of free sulfur, for materials vulcanized with sulfur; solvent swelling, applicable to articles or specimens which do not contain a high amount of extractables; hardness; modulus at low extension; and set properties.
Hydrogenation of Butadiene Rubber Solutions. II. Influence of the Solvent with Palladium-on-Calcium Carbonate Catalyst
Authors: Yakubchik A. I. , Gromova G. N. 
Published: February 2011

Abstract
Experiments with allyl alcohol demonstrated the influence of the nature of the solvent on the speed and degree of hydrogenation of an unsaturated organic compound on palladium-on-calcium carbonate catalyst. Butadiene rubber was hydrogenated on palladium-on-calcium carbonate in 2,2-dimethyldioxane-1,5 (DMD), and specimens of hydrorubber insoluble in that solvent were obtained. The same relation between degree of hydrogenation and properties was found for hydrorubber obtained with palladium-on-calcium carbonate catalyst in 2,2-dimethyldioxane-1,5 as had been established for hydrorubber obtained in heptane with the same catalyst : fall in relative viscosity of benzene solutions, lowering of refractive index, and fall in the temperature of vitrification of the rubber with increasing degree of hydrogenation. The selectivity of hydrogenation of the outer double bonds of butadiene rubber when hydrogenated in 2,2-dimethyldioxane is more clearly manifested than in the case of hydrogenation in heptane.
Organic Sulfides and Polysulfides. III. Reactions with Amines
Authors: Minoura Yuji 
Published: February 2011

Abstract
1. Mono-, di-, and trimethylamine when treated with benzyl and tolyl mercaptan give disufides ; on the other hand, thioglycolic acid gives the monosulfide. 2. Aniline and diphenylamine do not react with mercaptans or organic sulfides. 3. Mono-, di- and trimethylamine react with organic polysulfides. The tri- and tetrasulfides of the tolyl and benzyl series give disulfides by desulfurization. The glycolic acud sulfides are desulfurized to monosulfide. 4. The relative desulfurization activities of mono-, di- and trimethylamine are (CH3)3N &lt; CH3NH2 &lt; (CH3)2NH. This order is the same as for the basicity of these amines. Aromatic amines, because of their weak basicity, do not react with organic polysulfides. 5. The relative ease of desulfurization is in the order glycolic acid &gt; benzyl &gt; tolyl. The more sulfur a polysulfide contains, the more readily it desulfurizes. The mercaptan to disulfide reaction rate is faster than desulfurization of polysulfides.
Organic Sulfides and Polysulfides. VI. Reactions of Metallic Oxides with Polysulfide Rubbers
Authors: Minoura Yuji 
Published: February 2011

Abstract
1. Both mercaptides and disulfides were obtained by the reactions between benzyl mercaptan or tolyl mercaptan with zinc oxide or lead oxide. Qualitatively, mercaptides were formed from benzyl mercaptan easier than from tolyl mercaptan, and lead oxide reacted with mercaptan easier than zinc oxide with mercaptan. From the fact that no metallic sulfide was present, disulfides were likely formed from the oxidation of mercaptans by air. 2. The mono- or disulfides of the benzyl and tolyl series did not react with zinc oxide or lead oxide. 3. Neither tolyl tri- nor tetrasulfide reacted with zinc oxide, but benzyl tri- and tetrasulfide reacted with zinc oxide to give zinc sulfide. In the case of benzyl trisulfide, hydrogen sulfide, stilbene and benzaldehyde were formed, and in the case of tetrasulfide, we found the formation of hydrogen sulfide, stilbene, benzaldehyde and sulfur. 4. The tri- and tetrasulfide of both the benzyl and tolyl series reacted with lead oxide and they gave lead sulfide and organic disulfide. That is, they were desulfurized by lead oxide. In these reactions the benzyl series was more reactive than the tolyl series and the tetrasulfide was more reactive than trisulfide in the same series. 5. Lead oxide reacted with polysulfide easier than zinc oxide. 6. From the results of reactions between metallic oxide with mercaptan or other sulfide, it was concluded that the vulcanization mechanism of polysulfide rubber by metallic oxide is the reaction represented by Equations (1) to (4), the products being converted to high polymer without formation of a network of polysulfides.