bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tire Cord Fatigue and Fatigue Testing
Authors: Goy R. S. 
Published: February 2011

Abstract
Examination of failed tires shows that fatigue failure mostly occurs on the inner plies, i.e., those subjected to compressive bending stress when the sidewall is bent. Continual flexing of the sidewall leads to a reduction of tensile strength of the cords until eventually the sidewall breaks up and the tire fails. This fatigue failure is essentially a function of the complex structure of the tire. When a tire is inflated all the cords are in tension throughout and when it is loaded the sidewall of that part of the tire in contact with the ground is bent so that some of the cords are subjected to relieved tensile stress or, if the deflection is very great, to compressive stress, and the rest of the cords to tensile stress. When the cord goes from tension to compression it tends to collapse but this is complicated by the constraining action of the surrounding rubber. If the tire now rotates the cords will be subjected to alternate tension and quasi-compressional stresses leading to ultimate failure. Fatigue performance is usually assessed by the average mileage to failure of the tire. If the plies of a tire are tested by extracting cords before failure occurs it can be shown that there is a progressive loss of strength of those plies undergoing compression. It has been asserted that this drop is linear with tire life and is greatest on the innermost ply, i.e., at the point of greatest compression. The outer plies undergo a cyclic increase and decrease of tension at constant stress and although there is a small reduction in breaking strength, this does not usually contribute to tire failure.
Viscosity of Natural Rubber Solutions at Very Low Rates of Shear
Authors: Golub Morton A. 
Published: February 2011

Abstract
The shear dependence of viscosity of benzene solutions of natural rubber was studied at rates of shear from about 500 down to less than 1 sec.−1. Measurements involved following the change of pressure head with time of the various solutions flowing in a capillary, U-tube viscometer. Curvature in the plots of the logarithm of pressure head versus time indicated non-Newtonian flow. From such curves, reduced viscosity data over the above-mentioned shear range were readily derived. As a check, data over the range 100–500 sec.−1 were also obtained with a five-bulb viscometer of the Krigbaum-Flory type, and these data overlapped those obtained with the U tube. The reduced viscosity increased very sharply with decrease in gradient, making extrapolation to the viscosity axis quite unreliable. However, a theoretical relation proposed by Bueche fitted the composite data rather well. This work furnished a nice technique for determining the zero shear reduced viscosity (ηsp/c)0 without the necessity of performing an uncertain extrapolation: evaluate the parameters of the Bueche formula which best satisfies the experimental data over a fairly wide range of shear rates, and then calculate (ηsp/c)0 directly.
Interaction of Rubber and Carbon Tetrachloride
Authors: Pande J. B. , Raghunath D. , Ramakrishnan C. S. 
Published: February 2011

Abstract
Carbon tetrachloride has been used for studies on the solution properties of natural rubber. It has been tacitly assumed that no chemical reaction between the two takes place; but carbon tetrachloride has been found to show a negative heat of mixing with natural rubber. There is absorption of heat (0.37–1.36 cal./g.) with benzene, dichloroethylene and toluene, while there is evolution of heat (2–3 cal./g.) with carbon tetrachloride and chloroform. There is considerable evolution of heat on mixing cellulose triacetate with tetrachloroethane and the solvent is found to be completely bound with the polymer. It appears therefore that similar combination between rubber and carbon tetrachloride may occur, when these are brought together. An indication of chemical interaction of carbon tetrachloride and rubber has been found in an examination of the spectra of carbon tetrachloride solutions of natural rubber. Chemical analysis of rubber, aged in solution at the laboratory temperature, showed that chlorine was incorporated into the rubber. In the present investigation a progressive detailed study of the system of deproteinized rubber-carbon tetrachloride has been carried out from the instant the two are brought in contact till either a homogeneous solution (in darkness only) or a gel is obtained (visible radiations).
Tack of Pressure-Sensitive Tape
Authors: Chang Franklin S. C. 
Published: February 2011

Abstract
A new method has been found, as a result of this investigation, for measuring the tack of pressure-sensitive tape, which is simple and precise enough for practical purposes. By using this method, tack testing yields reproducible quantitative records in lieu of the ambiguous descriptive results from the empirical finger test. In light of the fact that, of the tapes made with the same adhesive, the one with crepe paper gave lower tack than the one made of flat paper, surface of contact must be one of the factors determining tack. Any pressure applied on the tape after the tape is put on the testing panel would, to a certain extent, increase the contact surface, hence, the force required to peel the tape from the panel. The stiffness of paper, through the depression effect, would have the same effect on the peeling force, in this case, the adhesion strength. Since tack is defined to be free of added pressure and depression effect, this explains the independence of tack and dependence of adhesion strength on stiffness of paper. Fom this point of view, one may consider tack as the limiting value of adhesion strength.
Helical Spring Stress Relaxometer
Authors: Berry J. P. 
Published: February 2011

Abstract
Changes in the tensile properties of rubber are obviously of great practical importance. Consequently, measurements of the change in force required to maintain or produce a given extension under controlled conditions of temperature and atmosphere have frequently been made and have advanced our understanding of the physical process of crystallization and of the chemical reactions responsible for thermal aging to the extent that they may become routine test procedures. The decrease in the force required to maintain a constant extension during the period of aging (stress relaxation) has been the most common measurement, in part because rubber elasticity theory predicts an equality between the fractional decrease in force and the fraction of the network chains originally supporting the stress which have become ineffective. Stress-relaxation behavior may characterize the type of scission reaction occurring; for example, the stress relaxation of most vulcanizates can be interpreted as a first-order scission of crosslinks, and not as a random scission of monomeric units in the chains between crosslinks. Stress-relaxation results, however, do not provide all the necessary information on network changes—the final properties of the rubber depend not only on crosslink or chain scission but to a comparable degree on crosslink formation during aging, which does not affect the force at constant extension. To examine this second effect requires measurements on the intermittent stretching of an unstrained sample to a constant extension. Parallel measurements of force at constant and intermittent extension under identical aging conditions are therefore required. The several designs of apparatus already described have usually been rather complicated and require practice and skill in use. A simple apparatus developed in these laboratories, which can readily be used for routine operations, is described in the following paragraphs. The fractional change in force is read directly from a vernier scale on the instrument, and may be immediately plotted on a force-time graph, preferably as log10 (force/forcet=0) vs. time (cf. Reference 3).
The Vulcanization of Elastomers. X. The Vulcanization of Natural Rubber with Thiuram Disulfides (V)
Authors: Lorenz Otto , Scheele Walter , Redetzky Wolfgang 
Published: February 2011

Abstract
The kinetics of crosslinking natural rubber during vulcanization with tetramethyl and tetraethylthiuram disulfide was investigated. The following results were derived: 1. The increase of crosslinking during vulcanization which was measured by the change of reciprocal swelling is first order over a wide range of reaction time and temperature. 2. During vulcanization, crosslinking and dithiocarbamate formation are reactions which proceed with identical rate. From this we had to conclude that the formation of dithiocarbamate is the immediate cause of the crosslink formation. 3. The concentration of the thiuram disulfide decreases much faster with respect to vulcanization time than crosslinking increases. In other words, the thiuram decrease can only be considered a reaction which precedes crosslinking.
Improved Resilience in Butyl Rubber through Chemical Modification
Authors: Leeper H. M. , Gable C. L. , D'amico J. J. , Tung C. C. 
Published: February 2011

Abstract
A new approach is presented toward obtaining improved properties in Butyl rubber vulcanizates through chemical modification of the Butyl rubber polymer by N-methyl-N,4-dinitrosoaniline. Chemical modification by this additive may be carried out in a Banbury mixer at conventional mixing times and temperatures. The use of modified polymer is advantageous in both black- and non-black-loaded stocks and is advantageous also with respect to variation over the spectrum of vulcanizing systems which are normally used with Butyl rubber. A successful plant demonstration of chemical modification has been carried out.
Chemical Aspects of Reinforcement
Authors: Watson J. W. 
Published: February 2011

Abstract
Hydroxyl free radicals were chemisorbed on to the surface of fully reinforcing carbon blacks by reacting them with an aqueous solution of potassium persulfate or of sodium hypochlorite. Both treatments caused a marked decrease in reinforcing ability, from which it was concluded that free radical interaction between these carbon blacks and rubber is a factor in reinforcement. Bound rubber and swelling index, which were determined for commercial carbon blacks covering the full range of particle size used in rubber compounding, were found to be no better related to reinforcing ability than was specific surface. In addition, after hydroxyl free radical treatment, bound rubber and swelling index remained unaltered though the reinforcing ability had been reduced. It was concluded, therefore, that the free radical interaction between carbon black and rubber which contributes to reinforcement occurs mainly during vulcanization, not during milling.
The Action of Finely Divided Solid Substances on Elastomers
Authors: Endter F. , Westlinning H. 
Published: February 2011

Abstract
The most important conclusions drawn from the concepts discussed can be summarized as follows: 1. The interaction between instability points of the electrostatic surface potential of fillers and the electronic structure in rubber or rubberlike substances leads—as a result of Coulomb's attraction between surface field and induced dipole moment—to at least temporary fixation of rubber molecules at the filler surface. 2. Polarization of the double bond is linked to a very slow process of molecular rearrangement. 3. The rubber molecules are constantly maintained in an unstable reactive state under the polarizing influence of the filler surface. 4. In the limiting case, double bond polarization leads to formation of new C—C linkages. The resulting high molecular compounds are closely related to the phenomenon of bound rubber. 5. The partially polarized state of the double bond is a function of the surface properties of the fillers. It has a substantial effect on the start and course of vulcanization. 6. The excitation conditions of the rubber molecules, which vary from filler to filler, appear to be the cause of the filler-specific properties of vulcanizates. To complete the picture of the interaction between filler and rubber, allowances must be made for a number of other factors. Specifically, chemical groupings at the filler surface will play their specific part in addition to the general processes, just as van der Waals' forces must not be disregarded in the adhesion of rubber molecules to the filler particles. However, the broad course of what happens in the interaction of filler and rubber seems to be determined by the processes described.
Chain Scission Efficiency in the Oxidation of Natural Rubber Vulcanizates
Authors: Veith A. G. 
Published: February 2011

Abstract
Natural rubber when it degrades under the action of oxygen does so primarily by a chain scission reaction. A technique has been developed by Tobolsky and coworkers for assessing the magnitude of this chain scission reaction in vulcanizates by means of continuous stress relaxation measurements. Since the result of the oxygen attack on the rubber is a chain scission reaction, the question of the efficiency of the reaction comes to mind. The influence of antioxidants is of importance in this regard as is the type of vulcanizate or network structure. This paper describes some measurements of the chain scission efficiency of a simple benzothiazolyl disulfide (MBTS) vulcanizate and the effect of several antioxidants on this chain scission reaction. Some of the complications inherent in this type of measurement are discussed. The first published report on the efficiency of the chain scission reaction in vulcanizates was given by Tobolsky, Metz, and Mesrobian in 1950. A more recent publication is that of Baxter, Potts, and Vodden in 1955. Tobolsky has interpreted the stress decay of gum vulcanizates at elevated temperatures as a direct consequence of the cutting of polymer chains of the network. The reduced stress is postulated as being equal to the chain density ratio:
The Determination of 2-Mercaptobenzimidazole
Authors: Zijp J. W. H. 
Published: February 2011

Abstract
2-Mercaptobenzimidazole (M.B.) is used in the rubber industry as an antioxygen or a deactivator. The term deactivator was proposed by J. Le Bras who distinguishes antioxygens from deactivators. This compound is prepared by Farbenfabriken Bayer A.G., Leverkusen, with the name of “Alterungsschutzmittel M.B.” The S.A. des Matières Colorantes et des Produits Chimiques de Saint-Denis (Paris) produces the zinc salt of this compound under the name of M.T.B.Z. The T.N.O. Institute for Rubber Research, which has developed methods for the determination of various antioxidants, has extended this work to the analysis of M.B. This compound, in fact, is not only of practical interest to the rubber industry, but it is also interesting in the study of the deactivator effect. The present paper describes the results obtained from this investigation. The method we have selected for the identification of M.B. was partition chromatography on paper. For the quantitative determination of M.B., we made no attempt to develop a procedure based on this technique since a precise colorimetric method of analysis in this field is not yet available.
Microstructures of Polybutadienes and Butadiene-Styrene Copolymers
Authors: Binder John L. 
Published: February 2011

Abstract
Polybutadienes and butadiene-styrene copolymers were prepared to study the effect of recipe variables on the physical properties and to learn whether there are correlations between the microstructures and physical properties. The changes in the microstructure of emulsion polybutadienes and butadiene-styrene copolymers of the types studied, which can be produced by either recipe variables or changes in temperature, are limited. The maximum amount of cis-1,4-addition amounted to 23 per cent (in the butadiene part of butadienestyrene copolymers) at 100° C, the maximum amount of trans-1,4- was about 80 per cent at −35° C, and the maximum amount of 1,2-addition was about 20 per cent. While the amount of cis-1,4-addition increases with increasing temperature, it is unlikely that polymers containing even 50 per cent cis-1,4-addition can be made at practical temperatures in emulsion systems. The structures of polybutadienes may be changed markedly by alkali-metal catalysts. The structure is affected by the kind of catalyst, by the temperature, and by promotors. Emulsion polymerizations are not likely to yield improved polymers for practical uses, but much can be done to tailor polymers for specific uses by using alkali-metal catalysts in bulk or solution systems.
Experimental Study of Low-Frequency Effects on the Dynamic Modulus of a Buna-N Rubber
Authors: Hutton Allen Q. , Nolle A. W. 
Published: February 2011

Abstract
The linear dynamic Young's modulus of a vulcanized Buna-N gum rubber was measured at frequencies of 0.05, 0.10, and 1.00 cps, in the temperature range − 22° C to 30° C, by a method in which a small differential sinusoidal elongation is superimposed on a 5 per cent static elongation. The width of the dispersion range on the temperature scale (the range in which the logarithm of the modulus increases steeply with decreasing temperature) is only about 10° C, contrasted with widths as great as 25° C found in previous measurements on a similar compound at frequencies of several kilocycles. The modulus-temperature plot shifts upward by only about 4° C per decade of frequency increase of the present range, contrasted with about 10° C per decade in the previous measurements at higher frequencies. It is concluded that this elastomer cannot be described properly by means of the “method of reduced variables”, in which the dynamic properties are ascribed to mechanisms having identical temperature dependence, and that the low-temperature behavior is governed by mechanisms distinct from those effective in the audio-frequency range at room temperature.
Softness, Time of Impact, and Internal Damping of Technical Rubber Mlxtures
Authors: Schreuer E. 
Published: February 2011

Abstract
It is shown that the Hertz theory of impact is applicable to the determination, from softness measurements, of the static modulus of elasticity and from impact tests, of the dynamic modulus of elasticity. A simple relation is then derived which connects the difference of these moduli and the internal damping in impact tests. This relation was checked with the rebound resilience values and proved to be valid for all measurements.
Chemistry in Carbon Black Dispersion
Authors: Barton Bernard C. , Smallwood Hugh M. , Ganzhorn George H. 
Published: February 2011

Abstract
The properties of carbon black and their effect on the physical properties of rubber vulcanizates have been extensively reported. The importance of particle size, reticulate structure, and surface characteristics are generally accepted. The beneficial effects of carbon black are believed to be due in large part to strong adsorption of rubber molecules on the carbon black surface. Many investigators have described the physical nature of this adsorption and have related it to the surface properties of the carbon black. Chemical bonding has also been suggested as being an important factor in the surface interaction between carbon black and rubber. The contribution of chemical bonding to the dispersion of carbon black and its effect on the physical properties of vulcanizates is the subject of the present paper. Gerke, Ganzhorn, Howland, and Smallwood and Bradley found almost twenty years ago that, when rubber-carbon black mixtures were heated at temperatures of 275–400° F, vulcanizates prepared from the mixtures had lower electrical conductivity, lower hysteresis, lower durometer hardness, higher modulus at large deformations, and greater resistance to abrasion than did vulcanizates of the corresponding unheated mixtures. These changes were ascribed to changes in the dispersion of the carbon black. Experimental data will be presented in this paper which suggest that these changes in carbon black dispersion are the result of chemical reactions between carbon black and rubber.
Infrared Analysis of Isomerized, Vulcanized, and Oxidized Natural Rubber
Authors: Salomon G. , van der Schee A. Chr 
Published: February 2011

Abstract
This paper is a continuation of our study on the infrared spectra of natural rubber and its derivatives. It was found previously that, in certain reactions of rubber, the original double bond (I) is shifted to the side group (II) and that this leads to significant changes in the chemical and mechanical behavior of the polymer. Others have also reported the occurrence of groups (II) and (III) in rubber and certain rubber derivatives. Group (II) is also found in synthetic polyisoprenes as a result of 3,4-polymerization. We have now measured the intensities of the absorption bands of the rubber spectrum and changes produced by cyclization and isomerization. Certain statements on the formation of (II) and (III) during vulcanization were at variance with our experience, but a detailed investigation cleared up some misconceptions. Modifications brought about by oxidation are chemically related to those produced by sulfuration reactions. A classification of oxidation reactions, based on typical changes in the infrared spectrum, will be proposed in the discussion.
Aging and Weathering of Rubber
Authors: Buist J. M. 
Published: February 2011

Abstract
Terminology in this field is confused and in need of clarification. In 1945, the various types of breakdown of rubber were classified as follows: (see PDF for table) In general, several of the effects cited above occur simultaneously, and may contribute jointly to the final result. General terms, such as aging and weathering, have been used widely, without any clear definition. Schidrowitz differentiates between the two terms as follows: weathering may perhaps be differentiated from aging by assuming that the former describes the effects of attack on rubber by the atmosphere under conditions of external exposure, i.e., to sun, air, rain, and wind, whereas the latter correlates effects produced in the absence of any continuous or excessive external exposure.
Departures of the Elastic Behavior of Rubbers in Simple Extension from the Kinetic Theory
Authors: Gumbrell S. M. , Mullins L. , Rivlin R. S. 
Published: February 2011

Abstract
It is shown that the equilibrium stress-strain behavior of highly swollen rubber vulcanizates in simple extension agrees with the predictions of the kinetic theory. The departures from these predictions which are found in dry or lightly swollen rubbers have been investigated, and it is shown that they can be described in terms of a single parameter C2. The magnitude of this parameter is large in dry rubbers, and decreases to zero at high degrees of swelling ; this decrease occurs linearly with decrease in the volume fraction of rubber. The value of C2 is found to be independent of the nature of the rubber polymer, of the degree of vulcanization, and of the nature of the swelling liquid. The possible significance of this parameter is discussed in light of these observations.