bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Method for Determining the Vulcanization Characteristics of Rubber Compounds
Authors: Peter J. , Heidemann W. 
Published: February 2011

Abstract
The complete course of the vulcanization curve is obtained by measuring the values of the dynamic shear modulus during a period while the test sample is held at the vulcanization temperature. The measurements are made about the position of zero distortion. The curves are in good agreement with those obtained by a step-cure method, and scorch data agree well with those obtained with the Mooney apparatus. The method has the following advantages and disadvantages. A. Advantages 1) The course of the vulcanization curve is established on a single sample without curing in stages. 2) Minimum material is required. 3) The test is quickly performed. 4) Good reproducibility is observed. 5) The unit lends itself readily to automatic recording so that one man can easily operate several instruments. B. Disadvantages 1) The apparatus should be operated by trained workers. 2) The cost of the apparatus is rather high.
Improving the Carbon-Rubber Bond
Authors: Braendle H. A. 
Published: February 2011

Abstract
Dry mixing involves compacting latex into solid rubber and then tearing it down to make a place for the carbon black. Likewise it involves compacting the carbon both before and after it enters the Banbury and then tearing it apart to develop its full surface. Such operations involve the application of enormous compacting and shearing forces that do neither colloid any good. By recognizing the time element the two colloids are brought together when they both are in a dispersed phase and therefore free to act as colloids; and by taking advantage of the time rate of this reaction the process effects the best spatial distribution of black in rubber so far attained. Nothing is added to interfere with the normal affinity of these two colloids. A better distributed and stronger bond results, as is evidenced by substantially enhanced road wear in tires made from such rubber.
Factors Affecting Laboratory Cut-Growth Resistance of Cold SBR Tread Stocks
Authors: Auer E. E. , Doak K. W. , Schaffner I. J. 
Published: February 2011

Abstract
By using an existing cut-growth test in a new way it has been possible not only to increase the reproducibility of the results, but also to show important relations between cut-growth resistance and modulus, or the elongation at break of cold SBR tread stocks. The logarithm of the cut-growth resistance of cold SBR vulcanizates as measured on a modified De Mattia machine, is shown to be a linear function of the 300 per cent modulus, except for certain undercured stocks. The slope of the curve is dependent on the type and the amount of black, but is relatively independent of the type of curing system, amount of antioxidant, and time of Geer aging. An equation has been found which relates cut-growth resistance at 150° F with the elongation at break of the vulcanizate. Except for stocks having black loadings in excess of about 55 phr and having in addition modulus values less than 800 psi, this relation appears to be nearly independent of black loading, type of black, curing system, time or temperature of cure, antioxidant concentration, and extent of Geer aging. The elongation at break of an SBR tread stock thus appears to be a primary factor governing its groove-cracking behavior. The relation between cut-growth resistance and modulus is of secondary significance and evidently depends upon the interrelation between the modulus and breaking elongation of these formulations. The breaking elongation, however, cannot be the sole factor governing the groove-cracking behavior; otherwise there would be no restrictions on the validity of the breaking elongation equation.
Mechanical Properties of Natural and Synthetic Rubbers
Authors: Bueche F. 
Published: February 2011

Abstract
It is felt that the reason for the large heat generation in SBR under flexure is now reasonably well understood. According to the present view, it is the result of the fact that Mn is too low in SBR thereby making it impossible to form a satisfactory network within the polymer. When the molecular weight is increased, as is done with SBR used in oil extended polymers, a more suitable network is formed in the rubber during vulcanization and as a result this rubber shows less heat development. Addition of carbon black to the rubber tends to increase the stability of the vulcanization network. Whether this is a result of the purely mechanical effects of solid particles imbedded in the existing network or whether the black actually enters into the network structure through chemical bonding is still not clear. In any event, it serves the function of retarding the creep of the polymer at long times. The fact that the addition of black increases the generation of heat for the same amplitude of deformation is probably the result of the necessary increase in Fmax needed to attain this deformation as predicted by Equation (1). The black's important function in regard to strength properties was discussed briefly in a previous report from this laboratory and will be investigated more in the future. It should be pointed out that many of the observations and conclusions presented here have previously been presented by others although it is believed that now they will appear more logical and conclusive. Obviously it is impossible to mention all the pertinent work carried out in this field which has led others to conclusions similar to those presented here. Omission of such references was made necessary by the mere fact of their great number.
Contributions to the Mechanism of Devulcanization II
Authors: Stafford W. E. , Allcroft J. B. , Sargent D. T. 
Published: February 2011

Abstract
Certain aspects of the reclamation of natural, butyl, and GR-S rubbers have been considered. While there are specific characteristic changes in all cases, e.g., zinc sulfide formation, etc., at the same time, important differences are recorded. The relation between some physical characteristics of cured reclaims and their parent vulcanizates have been discussed. The wide differences in the quality of reclaims, dependent upon the nature of the vulcanizing system employed in the parent vulcanizate, are interpreted as being substantially in agreement with previously published work, which has demonstrated the importance of curing mechanism upon reclaiming susceptibility.
Ski Rubber, Polyisoprene, Similar to Natural Rubber
Authors: Anikanova K. F. , Betts G. E. , Zhakova V. G. , Komskaya N. F. , Karmin B. K. , Priss L. S. , Reznikovskiy M. M. , Chernikina L. A. , Sheteyn E. B. 
Published: February 2011

Abstract
Years of research at the S. V. Lebedev All-Union Scientific Research Institute for Synthetic Rubber have provided industry with a number of methods for making synthetic rubber from isoprene. Of all the known synthetic rubbers this comes closest to natural rubber in structure and properties; it is the best available substitute of natural rubber, possessing a high degree of elasticity and strength. The present article is a brief summary of the basic work on isoprene rubber done by the Scientific Research Institute of the Tire Industry. On the basis of this work recommendations were made for the development of the production of synthetic isoprene rubber and the substitution of isoprene rubber for natural rubber in the manufacture of heavy duty truck tires. By using different polymerization processes it is possible to produce isoprene rubbers whose chain structures are very similar, but whose molecular weights, and therefore physical and technological properties, are very different. The cis structure of the 1,4 polyisoprene chains is the basic structural element of the new isoprene polymer. Therefore these synthetic isoprene rubbers (SKI) obtained through catalytic polymerization when vulcanized show a crystalline structure when x-rayed in the stretched state. The x-ray photographs also show that the geometric distribution of interference spots in SKI rubbers corresponds to the distribution of interference spots in natural rubber, but that the relative intensities of the crystalline, liquid, and amorphous scatterings in the two rubbers are different (Figure 1).
Ozonolytic Degradation of Interpolymers of Natural Rubber with Methyl Methacrylate and Styrene
Authors: Barnard D. 
Published: February 2011

Abstract
The preparation of graft and block interpolymers of natural rubber and synthetic polymers has made it desirable that the number and size of polymer chains attached to rubber be readily determinate. The degradation of unsaturated polymers with tert-butyl hydroperoxide in the presence of osmium tet oxide has been used for the determination of free polystyrene in SBR and carbon black in several elastomers, and has recently been applied to the present problem. The accurate determination of the rubber content of interpolymers by quantitative ozonolysis essentially according to the method of Boer and Kooyman suggested that this might be made the basis of isolation of the attached polymer, the rubber being degraded into fragments of low molecular weight, from which the polymer could be separated by conventional techniques. The method should be applicable to any interpolymer, or mixture, of a polyunsaturated and a saturated polymer and is illustrated with reference to interpolymers of natural rubber (NR)-polymethyl methacrylate (PMM) and NR-polystyrene (PS).
Vulcanization of Elastomers XV. The Vulcanization of Natural and Synthetic Rubber with Sulfur in Presence of Organic Bases (I)
Authors: Schelle Walter , Cherubim Martin 
Published: February 2011

Abstract
The results obtained from preliminary kinetic studies of the vulcanization of natural rubber (NR) with sulfur in the presence of organic bases may be summarized as follows. 1) The change of concentration of sulfur with time during reaction with NR for an initial sulfur concentration of 2.5 g per 100 g of mixture follows a fractional reaction order, n, of 0.6 at all temperatures. This result and the findings of other authors suggest that the reaction of sulfur with rubber is autocatalytic. From the temperature dependence of the rate constant the activation energy is found to be 35.3 kcal. 2) In the presence of zinc oxide and with a similar initial sulfur concentration, the reaction is first order and the activation energy, namely 35.6 kcal, is practically the same. 3) In the presence of diphenylguanidine (DPG) during cure sulfur decrease is a reaction of fractional order, n=0.75, and the activation energy is 29.8 kcal. 4) For a given initial concentration of sulfur and at constant temperature the rate of sulfur decrease during vulcanization increases with rising DPG content and reaches a limiting value; i.e., the rate constant depends on DPG concentration. Also, for various base (DPG is basic) concentrations sulfur decrease is of various fractional orders, n=0.5…0.7, etc. 5) The influence of base on the rate of sulfur decrease is interpreted broadly as a case of intermediate-catalysis (Zwischenstoff-Katalyse). 6) Vulcanization with sulfur is unaffected by tertiary amines and secondary amines have only a slight effect. 7) Primary amines, depending on basic strength, are strong accelerators of the rate of sulfur decrease. 8) In the presence of organic bases (aromatic amines) other than DPG, sulfur decrease is of fractional order where n varies between 0.5 and 0.7.
Mechanism of Mill Breakdown and Vulcanization in the Presence of 2-Mercaptobenzothiazole
Authors: Dogadkin B. A. , Tutorskiĭ I. A. , Pevzner D. M. 
Published: February 2011

Abstract
The mechanism of the action of 2-mercaptobenzothiazole, MBT, one of the most commonly employed accelerators of vulcanization, remains unclear. L. Wistinghausen and B. A. Dogadkin and D. M. Pevzner (1951, unpublished) showed that MBT is consumed in vulcanization, but these authors, because of the crudity of their methods, did not obtain quantitative relationships. In the present work there has been employed a preparation of the MBT which was tagged in the thiazole ring by the radioisotope S35. The synthesis of this compound was carried out in the following manner. MBT, tagged in both of its sulfur atoms, was first synthesized from phenyl isothiocyanate and elementary S35. The resulting MBT was then heated in a sealed ampule with an excess of inactive elementary sulfur for six hours at a temperature of 140°. Under these conditions the exchange reaction between the elementary sulfur and the sulfur of the mercapto group of the MBT reaches equilibrium. The activity of the resulting MBT fell to one-half of the original value. In this way the benzothiazole radical was tagged, by the introduction into the molecule of MBT of the radio-isotope S35 which does not exchange with elementary sulfur, under the conditions of vulcanization, and it thus became possible to measure simultaneously the velocity of the addition of the sulfur and the velocity of addition of the accelerator to the rubber.
Bound—Rubber Formation in Diene Polymer Stocks
Authors: Stickney P. B. , McSweeney E. E. , Mueller W. J. , Palinchak S. T. 
Published: February 2011

Abstract
The phenomenon of insolubilization of rubber by carbon black has been known for at least twenty-seven years. There have been many attempts during this time to establish a relationship between insolubilization, or bound rubber formation, and reinforcement of rubber by carbon black. It was postulated, as far back as 1925, that there was a parallelism between particle size and insolubilization. This in spite of the fact that the methods available for determining particle size of very fine powders at that time were relatively crude. It was postulated at that time that there was a close relationship between the phenomena of vulcanization and reinforcement. This concept has had recurrent periods of popularity since that time. The insolubilization of rubber by carbon black, or other pigments, has been estimated by various techniques by the early investigators in the field. In more recent work, the trend has been toward a very straightforward experimental approach. Bound rubber in an uncured rubber-filler compound is usually determined by static extraction using the same apparatus and techniques used in determining the gel content of unfilled polymers. It follows that, using this method, polymer insoluble because of crosslinking, or gel, cannot be distinguished from polymer insolubilized by incorporation of fine fillers. In investigating the formation of bound rubber, therefore, the presence of gel in the polymer being used, or formation of polymer gel during processing must be taken into account.
Aeration of Natural Rubber Latex. I. Effect of Polyamines on the Hardness and Aging Characteristics of Aerated Latex Rubber
Authors: Sekhar B. C. 
Published: February 2011

Abstract
Evidence has been presented to support the hypothesis that the absorption of oxygen by ammoniated latex at room temperatures creates reactive groups on the rubber hydrocarbon. These reactive groups impart to the rubber peroxidic properties. Such peroxidic group formation is responsible for the breakdown and build up of rubber under different conditions of storage. Suitable reducing systems, particularly the alkylene polyamines crosslink rubber in latex and enhance the aging properties of rubber.
Monolayer Studies of Some Hydroxylated Polyolefin Rubbers
Authors: Dean W. R. , Perera V. , Glazer J. 
Published: February 2011

Abstract
The study of high polymer monolayers by the Langmuir balance technique has been almost wholly restricted to those polymers which contain polar groups, e.g., cellulose, proteins, polyacrylates, etc. Nonpolar polymers do not spread and so little attention has been paid to the hydrocarbon rubbers. Wall and Zelikoff have reported that natural rubber, gutta-percha, and butadienestyrene copolymers do not form stable monolayers on water, but that when these materials are modified chemically by thiocyanogen they form relatively thin films of varying thickness. Sivaramakrishnan and Rao have recently confirmed that natural rubber does not form a monolayer on water. However, they find that it spreads spontaneously on a subsolution of aqueous acidic potassium permanganate. We have investigated the surface reaction between certain polyolefins and aqueous permanganate ; the kinetic features of these reactions, discussed elsewhere, suggest that definite chemical end-products are formed on the surface. The purpose of this communication is to characterize the end-products obtained from natural rubber (cis-1,4-polyisoprene), gutta-percha (trans-1,4-polyisoprene), polybutadiene, and two butadiene-styrene copolymers of differing styrene content, when these react under controlled conditions at the surface of an acidic aqueous permanganate subsolution.
Thermodynamics of Shrinkage of Fibrous (Racked) Rubber
Authors: Oth J. F. M. , Flory P. J. 
Published: February 2011

Abstract
Highly oriented natural rubber samples of Roberts and Mandelkern, prepared by racking and subsequently crosslinked using γ-radiation, undergo a spontaneous shrinkage upon melting which closely resembles the shrinkage of collagen. If the transformation is arrested by application of a tensile force, a state of equilibrium may be established between two distinct zones, or phases, one being totally amorphous (shrunken) and the other unchanged (i.e., racked). Determination of the stress τeq required for phase equilibrium at various temperatures is described. Extrapolation to τeq=0 gives equilibrium melting temperatures Tmi, which are about 8° below the temperatures Tsi for spontaneous shrinkage. The heat of transformation of racked to amorphous rubber calculated from the dependence of τeq on T is 4.5 cal g−1. Since the degree of crystallinity is only 0.24, the heat of fusion calculated for 1 g of crystalline rubber is ca. 19 cal, which agrees satisfactorily with the value 15.3 cal, deduced by Roberts and Mandelkern through use of the melting point depression method. The shrinkage of racked rubber displays all of the important features associated with the similar contraction of fibrous proteins.
Changes in the Specific Volume of Rubber during Elongation
Authors: Kusov A. B. , Trofimova V. I. , Nilova Yu I. 
Published: February 2011

Abstract
1. It was shown that an increase in volume under strain, which reaches 2% at the maximum elongations, is observed in both loaded and unloaded stocks based on different rubbers. 2. The curves of specific volume versus elongation are characteristically S-shaped in the general case, and the inflection points of these curves correspond to the same elongations as do the inflection points in the curves of stress versus elongation. 3. Natural rubber stocks show a drop in volume, related to the crystallization of the rubber, until a certain elongation is reached ; the higher the state of cure, the higher this elongation.
The Role of Metal Oxides as Activators of Vulcanization
Authors: Feldstein M. , Orlovsky P. , Dogadkin B. 
Published: February 2011

Abstract
1. The activation effect of metal oxides on the process of culvanization of nonpigmented compounds of rod polymerized sodium butadiene rubber differs from the effect in rodless polymerized rubber. In the latter case zinc oxide not only is not an activator but it retards the vulcanization process. 2. The role of activators depends, to a large degree, on the type of vulcanization accelerator and active filler used. 3. Metal oxides increase the amount of structure formation in the vulcanizate. 4. With regard to butadiene styrene rubber (SKS-30A), calcium hydroxide appears to have stronger activating effect on vulcanization than zinc oxide. 5. The special effectiveness of calcium hydroxide in compounds of butadiene styrene rubber is a result of its independent structure forming ability and accelerating influence on the reaction between rubber and sulfur. 6. Magnesium oxide has a positive influence on the technical properties of rubber and on the durability of tires prepared with butadiene styrene and sodium butadiene rubbers.
Vulcanization of Elastomers. 14. Role of the Oxide in Vulcanization with Compounds of the Thiuram Series. I
Authors: Scheele Walter , Toussaint Horst-Eckart , Stange Peter 
Published: February 2011

Abstract
The present paper is concerned with the influence of TETD concentration and of zinc oxide content upon the kinetics of the vulcanization of natural rubber and Perbunan 2818 with TETD. The following results were obtained for vulcanization at 120° C. 1. The velocity constants of TETD decrease and ZnDEDC formation are linear functions of the zinc oxide content at constant TETD concentrations. 2. If TETD and zinc oxide are present in constant molar mixing ratios, then the velocity constant of TETD decrease is independent of the amount of the mixture while that of ZnDEDC formation rises linearly with zinc oxide addition. 3. The velocity constant of TETD decrease diminishes with increasing TETD concentration when the zinc oxide content of the mixture is held constant. Under these conditions the velocity constant of ZnDEDC formation remains unchanged. 4. Everything shows that the velocity constant of ZnDEDC formation depends only on the zinc oxide content of the mixture while that of TETD decrease is dependent on the molar ratio of zinc oxide and TETD. 5. The relationships found are expressed mathematically, and the practical significance of the relationships is pointed out.
The Chemical Structure of the “Popcorn” Polymer of Butadiene
Authors: Yakubchik A. I. , Spasskova A. I. 
Published: February 2011

Abstract
1. The chemical structure of spongy butadiene polymer, obtained at 15–20° was examined by the ozonolysis method. 2. The per cent of chains with external double bonds in the spongy polymer was found to be 22.8%. 3. The spongy polymer of butadiene is composed, like the rubbery polymers, of chains with external and internal double bonds. 4. It was established that parts of the molecule of spongy polymer have the same structure as the rubbery butadiene polymers: -1,4-1,4-; -1,4-1,2-1,4-; -1,4-1,2-1,2-1,4-. 5. A chloroform-soluble rubberlike polymer was separated from the butadiene autopolymer. The degree of unsaturation of the chloroform-soluble polymer was determined (86.7%), also the relative content of internal and external double bonds.
Organic Sulfides and Polysulfides. IV. Reactions with Doctor Solution, Silver Nitrate, Cupric Acetate and Lead Acetate
Authors: Minoura Yuji 
Published: February 2011

Abstract
1. In mixtures of doctor solution and benzyl and p-tolyl sulfides, di-, tri- and tetrasulfide reacted and formed lead sulfide, but monosulfide did not react. 2. In the case of thiodiglycolic acid and dithiodiglycolic acid, dithiodiglycolic acid gave lead sulfide. 3. Sulfur gave lead sulfide by reaction with doctor solution. 4. Mercaptide formed by the reaction between silver nitrate and mercaptan. Mono- and disulfide of the benzyl and tolyl series gave no reaction. Tri- and tetrasulfide showed desulfurization, and gave disulfide. Dithiodiglycolic acid reacted with silver nitrate and gave silver sulfide. 5. Lead acetate and cupric acetate reacted readily with mercaptan. Mono-, di-, tri- and tetrasulfides of the benzyl and tolyl series gave no reaction even on heating. 6. Mercaptan was most reactive in the reactions with doctor solution and with silver nitrate. The more sulfur the organic polysulfide contained, the more reactive it was. The relative order of reactivity in these series were : glycolic acid &gt; benzyl &gt; tolyl.