bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Strain Dependence of Rubber Viscoelasticity. II. The Influence of Carbon Black
Authors: Mason P. 
Published: February 2011

Abstract
In Part I of this series it was shown how variations in the dynamic Young's modulus with extension could be represented by linear relations for gum rubbers in the region of 0 to 100% extension. The present work uses a similar treatment to examine how the viscoelastic behavior of natural rubber within this extension region is affected by the incorporation of two carbon blacks of widely differing colloidal activity. One of these materials, MT black, consists substantially of spherical particles with a mean diameter of about 0.4 microns: electron microscopy of cut surfaces of the black-rubber compound showed that the individual particles were well-dispersed. The finer material, HAF black, has a mean particle diameter of about 0.04 microns but exists in the rubber compound in a flocculated condition with aggregates up to about 0.3 microns in diameter. The rubber containing the coarse, MT black yielded linear strain relations enabling a direct comparison to be made with the behavior of the gum: the HAF material did not give linear relations for either the dynamic or the equilibrium Young's modulus. To facilitate discussion of this behavior it is desirable to set out more explicitly than in Part I the model underlying the analysis.
Degradation of Polymers
Authors: Wall Leo A. , Flynn Joseph H. 
Published: February 2011

Abstract
Recent literature pertaining to both the theoretical aspects and experimental results of the degradation of polymers by heat and radiation is reviewed and critically evaluated. Theories of random and chain thermal degradation of vinyl polymers and co-polymers are reviewed. The degradation of polymethacrylates, polyacrylates, poly-α-methylstyrene, polyolefins, polystyrene, other vinyl polymers, cellulose, polyesters, polyamides, dienes, natural rubber, and copolymers are discussed in the light of these theories. The thermodynamics and energetics of the degradation of these polymers is also reviewed. Chain scission, crosslinking, and gel formation and the kinetic mechanisms of these processes which take place during degradation of polymers by ionizing radiation and ultraviolet light are included. Degradative, rather than synthetic, effects are emphasized in the discussion.
Some Neglected Problems in the Rheology of High Polymers
Authors: Mooney Melvin 
Published: February 2011

Abstract
In accordance with custom, I have been asked, as a Goodyear Medalist, to address the Division of Rubber Chemistry of the American Chemical Society on the subject of my past work in the science and technology of elastomers. Hoping that I have correctly understood your desires, I shall now give you an informal, anecdotal story of some of this work. Going beyond this story of the past I shall also sketch, as I now see them, certain related unsolved problems, some of which have been rather neglected. While keeping in mind that detailed mathematics and theoretical argument would be inappropriate and even unwelcome on this occasion, I shall endeavor, with very little mathematics, to stimulate some of you to initiate programs of research on some of these problems, if you have not already done so. First let me tell you how, without realizing it, I became a rheologist. When I was employed by the United States Rubber Company in the fall of 1928, my first assignment was to study rubber plasticity, or the flow properties of crude rubbers and raw compounded stocks. When I was told of this problem in a conference with my group leader, Dr. Roscoe H. Gerke, there was a third person present, Dr. Ernest J. Joss, a physical chemist. Dr. Joss had only shortly before been given the same assignment; but with my appearance in the group, he was permitted to drop this work and give his full time to more congenial tasks. At the conference he turned over to me some talced strips of pale crepe which had been cut from a batch on a laboratory mill after various milling times. I knew nothing about rubber at that time; and if I had been asked to guess what these samples were, I could only have replied that they looked like fillets of sole sprinkled with flour and ready for the frying pan. The rheologieal testing devices for raw rubber that were available at that time were of two forms, the compression plastometer and the extrusion plastometer. I quickly decided that neither of these was suitable for the purpose, which, as I conceived it, was to measure the flow behavior of raw rubbers or stocks in their working condition as exhibited on a mill or calender or in a tuber.
Mechanism of Rupture of High Polymers
Authors: Gul V. E. 
Published: February 2011

Abstract
In connection with the wide distribution of high molecular weight compounds and the great successes in the field of synthesis of these materials, the study of the general principles of the processes of irreversible deformation and rupture of high polymer materials may be included among the important tasks of science and technology. In some cases it is desired to increase to the maximum the strength of the high molecular weight material, as for example in preparing articles from synthetic fibers, rubbers, plastics, etc., while on the other hand in others an increase in strength is undesirable. Thus, for example, food products, into whose composition high molecular weight materials are introduced, should naturally not be too strong. The preparation of reclaim from used rubber articles includes grinding. Here it is attempted to find such a combination of grinding conditions that will proceed with the minimum consumption of energy. In order to have the possibility of increasing or decreasing the strength of the high molecular weight substances, it is necessary to clarify the mechanism of ruptures and to know what is the relation between the forces of reaction between the structural elements of the material and tensile strength.
Dynamic Properties of Rubberlike Materials and the Isolation of Mechanical Vibration
Authors: Snowdon J. C. 
Published: February 2011

Abstract
Experiments to determine the dynamic mechanical properties of rubberlike materials frequently employ a sample of material sandwiched between two flat, parallel, and rigid surfaces. The sample is normally bonded to these surfaces or restrained from motion parallel to them by a perpendicularly applied static force. Figure 1 shows diagrammatically a sample attached to parallel rigid plates, which vibrate sinusoidally either in their own plane [Figure l(a)] or in a perpendicular direction [Figure 1 (b)]. In each case the lateral surfaces of the sample are unconstrained. The rubberlike material is commonly said to be stressed in shear in Figure 1 (a) and stressed in compression in Figure 1 (b). Actually, the rubberlike material in Figure 1 (a) will not experience a homogeneous shear deformation unless its thickness is small compared to the sample dimensions in every perpendicular direction. Again, the rubberlike material in Figure 1 (b) will not experience purely homogeneous compression because the lateral surfaces of the sample are not subject to an applied stress, and motion at and parallel to the interfaces between the sample and the plates is not permitted. The mechanical behavior of the rubber will in fact be governed primarily by its bulk modulus only when the lateral dimensions of the sample are large compared with the sample thickness. In this event the resilience normally associated with the rubber will not be apparent because the bulk modulus will be many times greater than the shear modulus of the material.
Determination of the Damping Characteristics of Fabric Reinforced Rubber Strips for Flexural Waves at Audio Frequencies
Authors: Wiener Francis M. , Gogos Creighton M. 
Published: February 2011

Abstract
The damping characteristics of fabric-reinforced rubber structures for flexural vibrations in the audio frequency range are of interest in studying the dynamic behavior of drive belts and automobile tires. To investigate these characteristics experimentally a strip of the material was secured at both ends by clamping the ends of the fabric and excited electromagnetically near the center into bending vibrations. The resulting displacements were observed by an electrostatic pickup arrangement. The quality factor Q was measured for the various resonant modes in the frequency range from near 100 cps to near 1000 cps for different specimens as a function of static loading. The results indicate that beyond about 200 cps the observed damping increases with frequency and appears to be primarily due to energy losses in shear. Although the specimens tested did not structurally duplicate tires or drive belts, it is believed that this study points up ways for the designer to control damping in accordance with the desired dynamic behavior of the finished product.
An Elastorelaxometer for Large Reversible Deformation of Elastomeric Systems and Polymer Solutions
Authors: Trapeznikov A. A. 
Published: February 2011

Abstract
1. A new instrument, the elastorelaxometer (based on the coaxial-cylinder principle) has been developed, for studies of large high-elastic deformations in relaxing colloidal gel systems and polymer solutions. 2. The effects of the following were investigated : a) width of the gap between the cylinders ; b) moment of inertia of the cylinder (with rapidly relaxing colloidal systems, cylinders of the minimum moment of inertia must be used) ; c) nature of the liquid in the bottom of the cylinder ; d) nature of the motion of the inner cylinder at different ultimate deformations. 3. Values of elastic recoil εc for different predetermined deformations ε have been determined in dilute aluminum naphthenate gels in decalin. It is shown that εc passes through a maximum, associated with transition beyond the yield value of the structure, with increase of ε. It is shown that εc can reeah 6000% in 2% gels.
Attrited Carbon Blacks and Their Behavior in Elastomers. III. Effects in SBR and Other Rubbers
Authors: Gessler A. M. 
Published: February 2011

Abstract
The cure of SBR is severely retarded in compounds with attrited blacks. This retardation, not found in butyl, natural, and acrylonitrile-butadiene polymers containing the same blacks, is associated with the sensitivity of SBR to acidity on the part of the black. The cure of SBR-attrited black compounds is sharply activated when glycerol or other aliphatic polyols are added in the compounds. The glycerol activation effect is unique with respect to both the polymer and the black. It is not obtained with SBR containing standard blacks, or with other elastomers, regardless of the black. Cure retardation and glycerol activation effects occur also only in attrited black-SBR systems which are cured with sulfur. They are not observed in peroxide cures. A combined reinforcement-vulcanization reaction is therefore envisioned to include the polymer, the black, sulfur, and glycerol as the reactants. When the compounds are properly cured with glycerol, attrited blacks lead to SBR vulcanizates with improved properties. The results are generally similar to those observed with butyl. Tensile strength and extensibility are increased. The vulcanizates are softer, as is evident from their reduced modulus and shore hardness. The dynamic properties are improved, both the dynamic modulus and the internal viscosity of attrited black-SBR vulcanizates being less than is ordinarily obtained with standard blacks. The increased activity of attrited blacks leads to greater heat treatment responses when glycerol is not present in the compound. The heat treatment of SBR containing both attrited black and glycerol results in a reversal of the normal heat treatment response. The reason for this reversal is not understood. Attrited blacks in natural, acrylonitrile-butadiene, and chloroprene rubbers give results similar to those in butyl. Cure retardation and glycerol activation effects are not encountered with these elastomers.
Ozonation of Butyl Rubber to Estimate Unsaturation
Authors: Ungar I. S. , Lutz G. A. 
Published: February 2011

Abstract
A method has been developed for the estimation of the unsaturation of butyl rubber by ozonation in selected solvents. Under a given set of conditions the ozonation method is reproducible to within 7 per cent and conceivably could be improved by further refinement. The unsaturation of a butyl rubber can be estimated in about 10 minutes when using ozonated oxygen and in about 15 minutes when using ozonated air.
Compounding SBR for Radiation Resistance
Authors: Anderson Herbert R. 
Published: February 2011

Abstract
The radiation resistance of butadiene-styrene cold rubber vulcanizates reinforced with carbon black can be increased materially by increasing the styrene content of the rubber, by extension of rubber with an aromatic oil, by incomplete curing with an accelerated sulfur vulcanization system, and by incorporation of retarders of radiation damage. Incomplete curing produces vulcanization intermediates which are affected by the ratio of sulfur to accelerator and by cure temperature to retard radiation damage. Results of swelling and stress relaxation measurements indicate that extension of the polymeric network with an aromatic oil increases the amount of chain scission during irradiation and decreases the amount of crosslinking to produce a correspondingly more radiation-resistant material. These measurements also show that in the absence of oil the decrease in radiation damage obtained by incomplete curing and with antirads is primarily the result of retardation of crosslinking. However, in the presence of oil, incomplete curing promotes and antirads retard radiation-induced crosslinking and scission about equally. Substitution of air for helium as an irradiation atmosphere accentuates the scission reaction to diminish moderately the changes in stress-strain properties.
X-Ray Diffraction Comparison of Radiation Damage in Rubber
Authors: Shelberg W. E. , Gevantman L. H. 
Published: February 2011

Abstract
This paper describes the use of an x-ray diffraction technique to correlate rubber radiation damage with rubber composition. Correlations between radiation damage and composition are useful as guides for the development of superior radiation resistant elastomers to be used as components of mechanical devices installed in high nuclear radiation fields. Rubber which is stretched and irradiated in an inert atmosphere is readily damaged by chain cleavage, manifested by loss of crystallinity, possible thinning, decreased x-ray diffraction intensities and eventual rupture (Figure 1). Loss of diffraction spot intensity was used to measure radiation damage in stretched rubber, and was tantamount to loss of crystallinity with little specimen thinning until just before rupture. Crystalline longevity was determined fur an irradiated “standard” rubber under standardized conditions and for other rubbers which were similar to the standard except for an added or substituted ingredient. A greater crystalline longevity connoted a greater radiation resistance, and the standard was used as 3 basis for comparing radiation resistance and composition.
Vulcanization of SBR by Gamma Radiation
Authors: Arnold P. M. , Kraus Gebard , Anderson R. H. 
Published: February 2011

Abstract
Experiments on the gamma-radiation vulcanization of butadiene/styrene rubber are described. A systematic investigation of the gamma radiation cure of a tread type compound is presented, which shows the dependence of the physical properties of gamma vulcanizates on the characteristics of the network formed. Swelling and stress relaxation measurements indicate that the crosslinking reaction is not accompanied by an excessive amount of main chain scission. Such measurements show also that the superior retention of stress-strain properties during aging of gamma vulcanizates is due to the elimination of post-vulcanization by chemical curatives. At equivalent crosslinking levels gamma vulcanizates display properties similar to sulfur vulcanizates. Gamma radiation overcomes the inhibition of vulcanization shown by a number of inorganic fillers and appears to enhance their reinforcement potential. The ordinarily high radiation dosage requirement for vulcanization may be reduced by incorporating heavy metal fillers into the rubber matrix. Such promotion depends on the atomic number, loading and state of subdivision of the promoting filler.
The Mechanism of Disulfide Decomposition under Vulcanization Conditions
Authors: Tutorskiĭ I. A. , Ginsburg L. B. , Dogadkin B. A. 
Published: February 2011

Abstract
1. 2,2′-dibenzothiazolyl disulfide (MBTS) labeled in the thiazole ring with the S36 isotope was synthesized. 2. During vulcanization of purified sodium butadiene rubber with MBTS the accelerator is observed to combine with the rubber simultaneously with the sulfur reaction. When all of the sulfur is combined the bonding of the accelerator is sharply retarded in spite of the fact that there is a significant amount of free MBTS left in the reacting mixture. 3. There is a linear relationship between the bound sulfur and the combined accelerator. 4. The rate constant for the combining of MBTS with the rubber increases linearly with the concentration of the accelerator. The limiting quantity of combined MBTS is about 75% of that introduced and does not depend on the concentration of the accelerator. 5. During sulfurless vulcanization with MBTS labeled with S35 in the disulfide bridge the quantity of combined accelerator determined chemically exceeds that determined radiomctrically by more than two times which indicates that there is an unsymmetrical scission of the MBTS. 6. During vulcanization with sulfur in the presence of MBTS labeled in the thiazole ring the ratio between the activity of the extract and the vulcanizate is significantly greater than unity. After all of the sulfur is combined this ratio becomes less than unity. An explanation of this phenomenon is reported.
Apparatus Study of Pore Formation Kinetics in Vulcanization
Authors: Albam M. A. , Pisarenko A. P. 
Published: February 2011

Abstract
The investigation of the processes of formation of microporous vulcanizates is a complex matter, since pore formation depends upon a whole ensemble of simultaneous chemical and physical processes some of which are : the decomposition of the blowing agent with the formation of gaseous products; the solution of these gases in the rubber hydrocarbon; the formation of an independent gaseous phase inside the compounded rubber stock and the foaming of the vulcanizate, which changes its elastic and plastic properties in the course of vulcanization; the escape of the gas. The biggest difficulty is the lack of a satisfactory procedure for investigation. Many specialists have investigated the kinetics of various pure blowing agents, but this differs from the kinetics of the decomposition of a blowing agent in various media, including a compounded rubber stock. In other investigations the force of the blowing action has been assessed from the size of the pressure exerted from the direction of the compounded stock upon a steel diaphragm. Nevertheless this method does not enable us to investigate the kinetics of the process or the influence of external pressure acting upon the compounded stock. All the methods proposed hitherto for investigation of the decomposition of blowing agents enable us merely to judge the relative amount of gas liberated by the various blowing agents, or else the action of whatever blowing agent in the “foaming” of the compounded stock. But with these methods it is impossible to determine the actual amount of gas formed in the compounded stock in the vulcanization period.
Rupture of Rubber. VIII. Comparisons of Tear and Tensile Rupture Measurements
Authors: Greensmith H. W. 
Published: February 2011

Abstract
In previous papers of this series a criterion for tearing of thin sheets of rubber vulcanizates was established on the basis of a characteristic tearing energy, the criterion being applicable either to the initiation of tearing at an incision or to the continuous propagation of a tear. An interpretation of the tearing energy in terms of the strength of a rubber as measured in tensile rupture tests was given, and in the present paper this is used in an attempt to relate tear and tensile rupture measurements, taking into account the observed effects of the speed of the test on such measurements. Data obtained from the tensile rupture measurements given in the preceding paper (Part VII) are first compared with the energy to initiate tearing at an incision with a tip of semicircular form. The data are then compared with the tearing energy for tears propagated at various rates.
The Breeding of Hevea Brasiliensis
Authors: McIndoe K. G. 
Published: February 2011

Abstract
The intrinsic yield of Hevea brasiliensis has been more than tripled over the past thirty-five years largely by the efforts of plant breeders. While it is not to be expected that progress will be as rapid over the next thirty-five years, yet the end is not in sight, and indeed new horizons are opening up. Coupled with the improvements made in other aspects of rubber culture, the industry is now in an excellent position to maintain its competitive status in world markets, and thus to contribute to the prosperity and economic stability of the tropical countries whose fortunes are so closely bound to it.
Biaxial Fatigue Testing Of Vulcanizates
Authors: Gehman S. D. , Rohall P. , Livingston D. I. 
Published: February 2011

Abstract
Extensive fatigue tests of vulcanizates of natural rubber and SBR were carried out using a cycle of alternate stretching in two perpendicular directions. It is shown that the data can be best handled statistically by assuming a lognormal distribution or by the use of extreme probability techniques. Illustrative results are given to compare the fatigue life of different types of SBR ; to show the value of the method for studying the effects of processing variations on fatigue life ; to determine the effect of various loadings of different types of carbon black; and to evaluate the effectiveness of anitoxidants and antiozonants. Exploratory tests using ozone instead of pinholes to initiate the failure eliminated the wide range in fatigue life between natural rubber and SBR, and in this respect gave a result which is more consistent with general service experience. This type of biaxial fatigue testing has many areas of usefulness for developing good endurance qualities in vulcanizates.
The Interaction of Carbon Black with Sulfur, MBT and TMTD in Vulcanization
Authors: Blokh G. A. , Melamed Ch. L. 
Published: February 2011

Abstract
The experimental data collected on the interaction of active centers of carbon black with the rubber on the one hand and of the active centers of carbon black with the sulfur and accelerators, and also with the antioxidants, on the other hand, provide a sound basis for belief that the problem of reinforcement of rubber by active fillers in the process of vulcanization cannot be explained from the physical aspect alone. The facts indicate the considerable importance of the chemical reactions between the active groups of carbon black and the compounding ingredients in the course of vulcanization.