bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiochromatographic Separation of Mixtures of Sulfur and Accelerators
Authors: Khodzhaeva I. V. , Kissin Yu V. 
Published: February 2011

Abstract
Co, Ni, Fe, Cu, Cd, Pb, Hg-diethyldithiocarbamates and radioactive tetraethyl-thiuramdisulfide (TETD*) were synthesized and the exchange between S35 and TMTD, S35 and MeDEDC, MeDEDC and TETD* was studied. The mixtures were separated by means of paper radiochromatography: S35 + TMTD by ethyl and methyl alcohol; TETD*+MeDEDC by ethyl alcohol. From the radio-chromatographic data the degrees of exchange were calculated.
Reactions of Polymers in Bulk. I. Influence of Fillers on the Degree of Crosslinking of Natural Rubber
Authors: Janacek J. 
Published: February 2011

Abstract
The relation between the degree of crosslinking determined by means of swelling and the theoretical total contact surface of rubber to carbon black was investigated with vulcanizates of two elastomers which were cured by various vulcanization methods and using various concentrations—even extremely high ones—of carbon blacks with different specific surface, degrees of chain structure and chemical activities. A constant, α, the magnitude of which generally depends upon the degree of agglomeration of the carbon blacks and on the chemical nature of their surface as well as on the polymers used and the vulcanization method, but which is practically unrelated to the filler concentration, has been proposed to express the relative crosslinking activity of carbon blacks.
Reactions of Polymers in Bulk. II. Influence of Crosslink Density on the Mechanical Deformation Properties of Filled Vulcanizates
Authors: Janacek J. 
Published: February 2011

Abstract
The mechanical deformation properties as characterized by the modulus at different deformation, hardness and rebound elasticity, were observed in elastomers filled with different carbon-black concentrations referred to the concentration of the effective chains of the rubber network as determined by swelling. The extent of the physical effect of carbon blacks in the elastomers was expressed by the difference between the mechanical deformation values of the filled and unfilled vulcanizates determined at a constant crosslink density.
Dependence of Bound Rubber on Concentration of Filler and on Temperature. II
Authors: Dessewffy Oliver 
Published: February 2011

Abstract
The dependence of the quantity of gel rubber on the extraction temperature was studied, for black-filled natural rubber compounds. Results show that the logarithm of the specific rubber gel quantity increases linearly with the reciprocal of the absolute temperature within a range of 25 to 80° C. The adsorption energies were calculated on the basis of the temperature dependence. The low energy values determined in this fashion supported the assumption that the bondings of the gel structure are largely “weak” bonds of a physical character. The author seeks to explain the observed adsorption phenomena by certain hypotheses.
The Diffusion of Sulfur 35 in Rubber. Effect of Carbon Black Loading on Sulfur Migration from the Breakers in Large Tires
Authors: Auler H. , Bostrom S. 
Published: February 2011

Abstract
This work had two principal objectives; in the first place, to make a contribution to clarifying the dependence of the diffusion characteristics of sulfur in rubber upon the carbon black concentration in the compound and secondly, we attempted to study the process of diffusion in vulcanized large pneumatic tires, using two different procedures with special experimental conditions. It may be assumed that the physical processes which lead to the diffusion of one material in another are basically well known. Work by Fick and by Langmuir and Dushman, among others, is especially valuable in explaining the diffusion process. while the first studies of diffusion of sulfur in rubber used optical methods, the application of sulfur 35 has been stressed for this purpose in the last few years. Auerbach and Gehman were first to use such a procedure. They, as well as Bresler, Prjadilowa and Chainman, followed the migration of sulfur into rubber during the diffusion process. The latter authors worked at technically interesting temperatures, from 130° to 150° C. Diffusion coefficients calculated from the experimental data were in the range 1.9×10−7 to 1.6×10−6 cm2/s. Studies by Mozisek and also by Ludwig represent more recent work in the field of sulfur diffusion. Ludwig used a different method than the preceding authors. After the test specimens were vulcanized, they were cut into thin slices with the microtome and the radioactivity which was present in the slices was determined. The excellent and detailed books by Jost, may be consulted by anyone with either a general or special interest in securing information in the field of diffusion.
The Reaction of Sulfur and Sulfur Compounds with Olefinic Substances. Part XII. Effects of Vulcanizing Additives on the Reaction of Sulfur with 2,6-Dimethylocta-2,6-Diene, and Their Bearing on the Mechanism of Sulfur Vulcanization of Natural Rubber
Authors: Bateman L. , Glazebrook R. W. , Moore C. G. 
Published: February 2011

Abstract
To summarize, we conclude that the course of the interaction of sulfur with an olefin alone is determined principally by the electrophilic reactivity of labile polysulfides and by the reactions of cationic-type intermediates, and that the essential function of zinc salts is to stimulate the reactivity of complementary nucleophilic species. Accelerators of the thiazole-type specifically promote the latter reactivity, as almost certainly do other common vulcanization accelerators, e.g., certain amines, metal dithiocarbamates and xanthates, and thiuram sulfides. It may be noted, for example, that reaction of 2,6-dimethylocta-2,6-diene with sulfur, zinc dibutyldithiocarbamate, and zinc oxide at room temperature, i.e., under conditions where direct sulfur-olefin reaction does not occur, yields a dialkenyl polysulfide and negligible cyclic sulfide (a result also found with tetramethylthiuram disulfide and zinc oxide plus zinc propionate at 140° C), indicative of sulfuration by the nucleophilic mechanism becoming almost fully dominant under especially favorable reaction conditions.
Accelerator Action of Certain Heterocyclic N-Thiocarbamylsulfendialkylamides
Authors: Éitingon I. I. , Feldshtein M. S. , Pevzner D. M. 
Published: February 2011

Abstract
1. The accelerator activities of heterocyclic N-thiocarbamylsulfendialkylamides based on piperidine, morpholine, and piperazine were investigated; it was found that compounds of this type are highly active accelerators of the vulcanization of natural and styrene butadiene rubber stocks, inducing rapid crosslinking and giving rubbers of higher modulus than the usual vulcanization accelerators. 2. The vulcanization kinetics in presence of these heterocyclic N-thiocarbamylsulfendialkylamides depends to a considerable extent on the nature and number of hetero atoms in the accelerator molecule. Morpholine and piperazine derivatives have a slower effect at the initial stage of vulcanization than the corresponding piperidine derivatives, and confer greater resistance to premature vulcanization of the rubber stocks.
Accelerator Activity of 2-Benzothizole Sulfenamide Derivatives and the Exchange of Benzthiazyl Thiyl Radicals with Radioactive 2-Benzthiazyl Disulfide
Authors: Feldshtei˘n M. S. , Chernomorskaya I. G. , Guryanova E. N. , Éitingon I. I. 
Published: February 2011

Abstract
The authors obtained data characterizing the accelerating activity of sulfonamide derivatives of MBT. The reactions of isotope exchange between such derivatives and MBTS labeled with S35 in the disulfide bridge were investigated, using chromatography to separate the components of the reaction mixture. It is shown that between these compounds there takes place an exchange of benzthiazyl radicals. A direct dependence is established between the accelerator activity of the sulfenamide compounds and their capacity for exchange of benzthiazylthio groups. The easier this takes place, the higher the activity of the compounds in the initial stage of vulcanization. The observed reactions of exchange of benzthiazylthio radicals may be used for the synthesis of sulfenamide derivatives of MBT labelled with radioactive S35.
Reaction of Tetraethylthiuramdisulfide with Alkali and Its Bearing on Vulcanization Reactions
Authors: Gessner Teresa 
Published: February 2011

Abstract
Klebanski and Fomina have reported on the action of alkali on tetraethylthiuram disulfide (TETD). They suggested the following equation for the reaction: (see PDF for diagram) This equation is based in part on a premise that TETM is one of the reaction products; we feel this premise is incorrect. As partial evidence for their proposed reaction scheme, Klebanski and Fomina claim the isolation of tetraethylthiurammonosulfide (TETM) from the reaction products. They give both the analysis figures and the melting point of the isolated substance. The melting point quoted by them is 64–65°. The melting point of TETM is, however, 28–33°. We have attempted the isolation of the substance reported by Klebanski and Fomina, and have repeated their experiment according to the published instructions. The only water-insoluble material which we were able to isolate, after 8 hours reaction with 2% aqueous sodium hydroxide, was unreacted TETD (73% of the starting material). The material isolated had a melting point of 68.5–70°, mixed melting point with TETD was 68.5–70°, the nitrogen and sulfur content was: %N 9.38, %S 42.82. Recrystallized from ether the substance melted at 70°, and analyzed as: %N 9.48, %S 43.05, mol. wt. 297; TETD requires; %N 9.53, %S 42.93, mol. wt. 296, m. pt. 70°.
Determination of Thiazole Type of Rubber Accelerators by Amperometric Titration
Authors: Chatterjee Pronoy K. , Banerjee D. , Sircar Anil K. 
Published: February 2011

Abstract
The method of amperometric titration has been applied for the quantitative determination of mercaptobenzothiazole, zinc benzothiazolylmercaptide and dibenzothiazolyl disulfide, the latter two being known to constitute the decomposition products of the first during vulcanization reaction. It has been found that mercaptobenzothiazole as it is, or formed by a suitable reaction from the other two accelerators mentioned above, can be quantitatively estimated amperometrically. The total amount of mercaptobenzothiazole present in a mixture of two or all three of the above-mentioned accelerators and also the total amount of mercaptobenzothiazole liberated in a mixture of two or three of them can be quantitatively estimated.
Determination of Amine Type Antidegradants by High-Temperature Gas Chromatography
Authors: Wise R. W. , Sullivan A. B. 
Published: February 2011

Abstract
High-temperature gas chromatography has been used successfully to quantitatively determine the amounts of high boiling amine antidegradants in vulcanized and unvulcanized rubber samples. The antidegradant content was determined by first extracting from the rubber sample the antidegradant and subsequently analyzing the extract by gas chromatography. The method is rendered quantitative by the use of an internal standard. Typical analyses of several rubber samples containing antidegradants are presented. The method is also applicable to the assay of commercial materials.
Nitrile Rubber-Polyvinylchloride Blends
Authors: Sharp T. J. , Ross J. A. 
Published: February 2011

Abstract
Vulcanizable blends of nitrile rubber and Polyvinylchloride combine excellent weather resistance with the low swelling in petroleum solvents of the nitrile rubbers. The Polyvinylchloride functions as a reinforcing agent and increases the hardness, modulus and tensile strength of the material. The principal disadvantages of the addition of the Polyvinylchloride are the reduction of low temperature flexibility and the poor compression set. By the use of suitable plasticizers in the former case and modification of the vulcanization system in the latter case, these disadvantages can be largely overcome. Mixing can be performed on a mill or in an internal mixer, but it is essential to flux the Polyvinylchloride at some stage or the improvement in weather resistance and physical properties is not obtained. By the use of rubbers of low Mooney viscosity, blends can be produced with good processing characteristics. Variations in the type of Polyvinylchloride can affect the final properties of the blends; general purpose suspension polymers are not recommended for use in masterbatches. Providing that a nitrile rubber containing a nonstaining antioxidant and a nonsulfur staining stabilizer for the Polyvinylchloride are employed, white or brightly colored vulcanizates can be obtained. Applications for these blends which are of interest include hose tubes and covers, belting, particularly food belting, cables and shoe soles.
Polyurethan VC, a Virtually Crosslinked Elastomer
Authors: Schollenberger C. S. , Scptt H. , Moore G. R. 
Published: February 2011

Abstract
Many of the outstanding physical properties that characterize elastomeric Polyurethans have been realized in a soluble, thermoplastic variety, Polyurethan VC, which displays the superficial properties of a rubbery vulcanizate at room temperature and so is considered to be virtually crosslinked. High tensile strength as well as good tear, abrasion, solvent, oil, and ozone resistance characterizes this polymer. Since these properties are realized in the unvulcanized state, many useful applications of the readily processable polymer can be made, avoiding the complications which attend the use of conventional (vulcanizing) urethan elastomers. Outdoor exposure and indoor accelerated weathering studies demonstrated a deficiency in the weather resistance of the raw polymer. Weather-induced changes, believed to be due to ultraviolet-initiated autoxidation, have been estimated by noting changes in the stress-strain properties as well as the ultraviolet and infrared absorption spectra of the polymer on exposure to natural and artificial weather conditions. The beneficial effects of certain carbon blacks, conventional antioxidants, and ultraviolet absorbers on the weather resistance of the polymer have been described.
Adhesion of Synthetic Rubbers to Various High Molecular Substrates
Authors: Voyutskiĭ S. S. , Vakula V. L. 
Published: February 2011

Abstract
In previous work the adhesion of certain synthetic rubbers to cellophane was investigated. In the present paper we present the results of determination of the adhesion of a considerably larger number of rubbers of varying nature to varying substrates, both polar and nonpolar—cellophane, polyamide and polyethylene films—and also two elastomers—the polar rubber SKN-40 and the nonpolar polyisobutylene. The resulting data allow us to draw certain conclusions as to the influence of the molecular structure of adherend and substrate. The adhesion of rubbers to substrates is defined by the film stripping resistance P, in g/cm. The joints were made by plying up a film of substrate (of cellophane washed free of glycerin, of polyamide, or of polyethylene) or of fabric covered with a substrate (SKN-40, polyisobutylene) with fabric strips to which the polymer under investigation had previously been applied from a solution. Not less than 0.025 g/sq. cm of the polymer was applied to the fabric strips, this being sufficient to give reproducibility of results. The plying up was effected by rolling the assembled halves of the joint with a rubber roller, which gave higher pressures than those required to achieve full contact of the surfaces of the elastomeric adherend and the substrate. Such a method of producing joints has definite advantages from the point of view of procedure over the method employed previously, because it makes possible elimination of the influence of prolonged and varying time of interaction of the adherend with the substrate in the drying out which is inevitable in joining an adherend by a solution.
New Vulcanizing Agents for Ethylene-Propylene Elastomers. II
Authors: Wei Peter E. , Rehner John 
Published: February 2011

Abstract
In searching for new vulcanizing systems for ethylene-propylene elastomers, we have found several more classes of active agents, heretofore undisclosed. They are: (a) perhaloalkanes and some polyhaloalkanes; (b) polyhalocycloalkenes; and (c) poly-N-halobenzoguanamines. Specific examples are: hexachloroethane, octachloropropane, octachlorocyclopentene, perchlorofulvalene, and N,N,N′,N′-tetrachlorobenzoguanamine. These agents are all effective in ethylene-propylene rubber, and some are capable of vulcanizing polyethylene, polypropylene, polyisobutylene, butyl, and highly unsaturated rubbers and their blends. The agents are most effective in the presence of sulfur. All are active in carbon black stocks, and at least some are active in mineral-filled and oil-extended stocks. Some of the vulcanizing agents can be accelerated by certain oxides and salts of metals widely distributed over the periodic system. Among the most active accelerators are iron compounds, such as iron tallate, stearate, naphthenate, octoate, and oxalate, and corresponding combinations of iron oxide and the free acids. These accelerators are antagonized by the presence of zinc oxide. The chemical diversity of these classes of vulcanizing agents and the complex behavior of the accelerators mentioned preclude an explanation of the vulcanization chemistry at this time.
Determinants in Research
Authors: Wiegand W. B. 
Published: February 2011

Abstract
We have now outlined some of the precursors of research, which we have called determinants. As to the Teammates, the record shows that the writer has been fortunate beyond his due. Flexibility in working theories, together with resourcefulness in techniques—prerequisites in any mayor research project—turned up when most needed. Trend lines, followed by extrapolation, we found essential, but tricky. Inversion, although great fun, is more a heady wine than a steady diet. The relatively high incidence of Hunches and Contacts, as decisive factors in research, emerges as perhaps the highlights of this modest study. These are determinants which seem to be independent of formal training; they are not to be found in college curricula. Even application forms do not ask “What is your record in successful hunches?” They are qualities which belong to other than the cognitive side of man. The same might be said about Action, which, as Dr. Sparks has reminded us, is an indispensable adjunct to any list of prerequisites for research. But how are these nonintellectual determinants fostered? How do certain individuals acquire the spark which seems to kindle their creativity—their Hunches, their flair for extracting honey from their Contacts, their drive, their motivation? Well, motivation seems to tie up with feeling. The Greeks thought that feeling centered in the diaphragm. With us it is the “heart.” In neither case is it the head. How does one go about acquiring this? In classical Greece kings and potentates sent their sons to one of two schools, not to learn certain skills, but to be exposed to two men—Plato and Isocrates. They counted on contact with these great teachers to inspire their sons and they rated this inspiration above instruction. Are we, perhaps, inclined to over-rate curricula and underrate the importance of personal exposure to teachers who possess, and can communicate, the imagination, the sweep and the scope, which we associate with greatness?
Inhibition of Hardening in Natural Rubber
Authors: Sekhar B. C. 
Published: February 2011

Abstract
It is well known that the polyisoprene of hevea latex undergoes considerable changes after its emergence from the tree. These changes take the form of chain scission or crosslinking depending on the conditions obtaining (see all References). In the solid state the predominant reaction that takes place on storage of rubber is one of crosslinking as indicated by the increase in Mooney viscosity, Williams plasticity and gel content. The plasticity of solid rubber changes continuously from the time it is prepared to the time it is used by the consuming industry. Considerable work has been carried out in the past to study this reaction with a view to controlling or inhibiting it. Wood suggested that peroxide or other free radical forming groups in the rubber may be responsible for the gelation of rubber on storage but gave no indication whether these groups were present in rubber as it leaves the tree or were formed subsequently. In a recent paper, it was shown by the writer that reactive groups are present in the rubber molecule as it leaves the tree. These reactive groups have the characteristic property of carbonyl groups or more specifically aldehyde groups. Condensation of these groups with other groups on the rubber hydrocarbon molecule, e.g., α-methyl or methylene groups, may be responsible for crosslinking of the polymer molecules. In support of this hypothesis, it was shown that reactive monofunctional amines or other carbonyl reagents are capable of inhibiting this crosslinking effectively, and that bifunctional amines can bring about crosslinking. The present investigation is an extension of this work and includes an examination of the effect of excess bifunctional amines, observations on the influence of formaldehyde in de-activating the naturally occurring amines in latex and a study of the reaction between hydroxylamine and a number of rubbers from different clones.
Mastication of Elastomers I. Natural Rubber in Nitrogen
Authors: Bristow G. M. 
Published: February 2011

Abstract
In accordance with theoretical expectation, the mastication of acetone extracted natural rubber in the absence of radical acceptors leads to gel formation. Unextracted rubbers undergo no gelation. The extent of gelation is determined almost entirely by the initial molecular weight of the rubber: under the conditions studied here rubbers of initial molecular weight less than ca. 3×105 do not gel on mastication. Only very small quantities of radical acceptors are required to repress gelation suggesting that acetone extracted rubber still contains appreciable quantities of such materials.
Size, Form and Flexibility of the Rubber Molecule
Authors: Schulz G. V. , Mula A. 
Published: February 2011

Abstract
Natural rubber can be brominated in dilute cyclohexane solution, whereby the molecular weight, corresponding to the bromine content, increases. For brominated rubber, increasing bromine content makes cyclohexane an increasingly poorer solvent, which is shown by a contraction of the molecule coils and a decrease in the second virial coefficient. Quantitative results were obtained through viscosity and light scattering measurements. Cyclohexane solutions of brominated rubber containing about 43% bromine have a θ point at room temperature. Here the second virial coefficient is zero and the coil has an ideal Gaussian density distribution. In this state the coil diameter is about 1.6 times bigger than for completely free rotation. A comparison of these data with X-ray low angle scattering could yield a quantitative measure of possible molecular branching. Brominated rubber with about one bromine per isoprene residue is a good starting material for the preparation of electron-microscope samples which can be used for the determination of the molecular weight distribution in rubber. The value of the weight average degree of polymerization determined by an electron microscope is in agreement with that determined through (1) light scattering and (2) ultracentrifuge and diffusion measurements. The molecular inhomogeneity of our sample is of the order of 0.5.