bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physics Does It in Rubber Research. Charles Goodyear Medal Address—1970
Authors: Gehman Samuel D. 
Published: February 2011

Abstract
From all this you can see that a physicist in rubber research can be a very busy person, both in theory and practice. Rubber science, already enriched by contributions from many disciplines, undoubtedly will continue to discover interests in some of the newer, advanced techniques in fields such as physics. I wish once more to express my appreciation for this opportunity to travel back upstream with you to glimpse a few memorable past scenes which fade again into the distance as we look to broader vistas and adventures ahead.
Surface Energy Effects for Small Holes or Particles in Elastomers
Authors: Gent A. N. , Tompkins D. A. 
Published: February 2011

Abstract
Expansion of a small spherical hole in a highly elastic solid is treated theoretically. Both elastic and surface energy terms are considered; the corresponding surface forces are assumed to be additive. The surface energy of the elastomer is assumed to be similar to that of simple liquids. Pressures or triaxial tensions required to inflate pre-existing holes to an indefinitely large size are calculated. Small holes require extremely large pressures, of the order of 1000 atm for holes of 10 A˚ radius. These results suggest a means of determining the distribution of hole sizes in elastomers and account, in principle, for experimental observations of cavitation processes. Detachment of the elastomer from a small rigid inclusion is treated in a similar way. The general absence of dilation or cavitation on stretching carbon black filled elastomers is thus accounted for solely in terms of the small size of these filler particles.
Volume Change Measurements of Filled Rubber Vulcanizates under Stretching
Authors: Shinomura T. , Takahashi M. 
Published: February 2011

Abstract
The stretching dilatometer of our own design was manufactured, and, using it, we investigated the effects of the types of fillers, the amount of fillers, and the curing time on the volume change phenomena of filled rubber vulcanizates under elongation. It was found that the Δυ/σr (the volume increase induced by the strain divided by the real stress) as a function of γ (the strain) pattern of carbon black loaded rubber vulcanizates was greatly different from that of a whitetex loaded rubber vulcanizate. This phenomenon was explained in the viewpoint of the superposition of the first type and the second type cavitations which had been mentioned in the previous paper. It was found that the critical strain γ0 is dependent upon the carbon black structures, and that the γ0 value decreases while the Δυ value increases with the amount of carbon blacks. It was also found that the Δυ value increases while the Δυ/σr value decreases with curing.
A Note on Stress Relaxation of Rubber Networks in the Vicinity of Room Temperature
Authors: Steiner G. , Tobolsky A. V. 
Published: February 2011

Abstract
The question of whether stress relaxation of natural rubber under normal usage at room temperature up to 100° C is caused primarily by chemical aging or physical phenomena connected with reversible changes is one which has been extensively studied. Thirion and Chasset investigated the relative effects of network relaxation and aging for dicumyl peroxide cured natural rubber in air and found network relaxation effects predominating below 55° C with aging becoming increasingly important at higher temperatures and longer times. In this study samples of natural rubber, cured by dicumyl peroxide, were relaxed both in air and in vacuum in an attempt to elucidate further the phenomenon of network relaxation. It was concluded that stress relaxation between 25° C and 100° C is much smaller in vacuum than in air, and that true equilibrium stresses are rapidly reached in vacuum.
A Mathematical Model for a Tire Sidewall
Authors: Clark S. K. , McIvor I. K. 
Published: February 2011

Abstract
A number of previous experimental studies on the cord load distribution in loaded and inflated bias-ply tires have revealed greatly different cord load fluctuation patterns between the crown and the side-wall regions of the tire. Typical among these is data taken from reference, where the cord load fluctuation measured at the crown center line of a typical bias-ply tire is as shown in Figure 1. The symmetry of this figure is easily explained by either bending or shell membrane considerations or by some combination of these. On the other hand, cord load fluctuations measured in the side wall of a bias-ply tire typically show fluctuations such as shown in Figures 2 or 3, also taken from the previously cited reference. Both of these latter figures show considerable asymmetry of the cord load as a function of position diagrams as the loaded tire is rolled through the contact patch. Bending of the side wall cannot account for such behavior as shown in Figures 2 or 3, since the changes in radius of curvature in the side wall region are completely symmetric about the center line through the contact patch, denoted by the zero degree point in Figures 2 and 3. Simple pressure vessel considerations are also not capable of explaining such diagrams, since changes in curvature in the side wall region are also completely symmetric and hence would result in symmetric stress distributions.
Influence of Chemical Nature on Flow Behavior of Polymers. I. Shear Rate and Temperature Dependence
Authors: Collins E. A. , Mass T. , Bauer W. H. 
Published: February 2011

Abstract
The flow behavior of low molecular weight liquid polybutadiene polymers was studied as a function of shear rate, temperature, and molecular structure. Measurements were made in the temperature range 15 to 50° C and shear rate range 1 to 15,000 sec−1 with a cone and plate and a capillary viscometer. Limiting low shear viscosity, flow activation energy, and critical shear rate marking onset of shear rate thinning were found to be strongly dependent upon the presence of functional groups such as hydroxyl, carboxyl, and nitrile. The modifying groups showed a greater effect than the molecular weight upon the properties measured.
Properties of a Trans-1,5-Polypentenamer Produced by Polymerization through Ring Cleavage of Cyclopentene
Authors: Haas F. , Nützel K. , Pampus G. , Theisen D. 
Published: February 2011

Abstract
Trans-1,5-polypentenamer can be produced with a high degree of uniformity by solution polymerization using complex catalysts of the Ziegler/Natta type. The state of order of the polymer indicates a rubber with good low temperature properties and crystallization behavior similar to that of natural rubber. There is therefore a fundamental difference between this material and other synthetic rubbers of the general purpose type. Trans-1,5-polypentenamer is easy to process, can be heavily loaded, and is therefore inexpensive to compound. Even when small amounts of the crosslinking agents are used, a high cross-linking yield is obtained and this makes it possible to produce vulcanizates that are resistant to dynamical stresses. As high green strength and good tack are present simultaneously, the material is suitable for use in the tire industry, particularly in carcass production.
Effect of Mechanical Shear on the Structure of Carbon Black in Reinforced Elastomers
Authors: Gessler A. M. 
Published: February 2011

Abstract
The primary aggregate structure in high structure blacks is broken down when the blacks are milled in rubber. The breakdown, it is shown further, involves the disruption initially of more easily disrupted forces, and then subsequently of more difficultly disrupted forces. If the total structure breakdown is segmented accordingly, one finds that carbon blacks differ markedly in the proportion of the breakdown which occurs in each segment. But only the breakage of more difficultly disrupted structure is identified with chemical changes in the black and with concomitantly increased carbon—polymer interaction activity, i.e., with enhanced reinforcement. In studying the breakage of aggregate black structure which occurs when the blacks are milled in rubber, the following factors are considered: (1) Carbon Black Concentration: Breakage increases continuously, though not steadily, with carbon black concentration. This result is used to emphasize the merits of concentrated black masterbatching as the means for producing high quality products from SBR, BR, and EPDM rubbers. (2) Carbon Black Structure: Taking the total structure breakage over a broad range of carbon black concentrations, the extent of the breakage increases with the extent of the primary aggregate structure in the original black. (3) Polymer Viscosity or Molecular Weight: The extent to which breakage occurs on milling increases with the polymer viscosity or molecular weight. Since this result clearly cites the need for high shearing forces during milling, the severe limitations which must attend the use of plasticizing oils is implied. (4) Open Mill vs Banbury Mixing: The extent to which breakage occurs in the Banbury is significantly less than that on the two roll mill. Evidence is presented to show that this, clearly, is a temperature related result and, as in (3) above, that the magnitude of the shearing forces is the critical factor.
Immobilization of Elastomers at the Carbon Black Particle Surface
Authors: Sircar A. K. , Voet A. 
Published: February 2011

Abstract
Determinations have been made of the amount of elastomer unextractable from unvulcanized masticated mixes with carbon black by a given solvent at boil, expressed as immobilized elastomer. Saturated and unsaturated elastomers varying in molecular weights from 2000 to 325,000, were used, while solvents of greatly differing boiling points and solvent power were employed. It could be shown that the bonding between elastomers and carbon black is not a simple adsorption, but involves a higher energy interaction, defined as chemisorption. At successively higher temperatures elastomer is increasingly removed from the carbon black surface. The temperature Tm, obtained by extrapolation of the linear relationship between amounts immobilized and temperature of extraction, represents the temperature theoretically required to eliminate all bonds between carbon black and elastomer and is therefore indicative of the bond strength. Data suggest the existence of a bonding energy spectrum. Upon graphitization, blacks show a considerable decline in high energy bonding ability for elastomers. Saturated elastomers show less bonding than unsaturated elastomers with the same furnace black. “Bound rubber” represents the sum total of physically adsorbed, mechanically entangled, and chemisorbed elastomer. The actual values are greatly dependent upon the procedure used. “Immobilized rubber”, indicating chemisorbed elastomer, is easily determined, is not influenced by the method, and is more significant as an indicator of reinforcement.
Effect of Sulfur and Dicumyl Peroxide on Vulcanization of Natural Rubber with Tetramethylthiuram Disulfide and Zinc Oxide
Authors: Manik S. P. , Banerjee S. 
Published: February 2011

Abstract
The salient features of both non-elemental sulfur vulcanization by TMTD and elemental sulfur vulcanization promoted by TMTD both in presence and absence of ZnO and stearic acid have been studied. TMTD increases the rate of DCP decomposition and lowers the crosslinking maxima due to DCP depending on its concentration. However, with higher amounts of TMTD the initial rate of crosslinking is increased with the increased amount of TMTD, while crosslinking maxima are still lowered due to reversion. ZnO or ZnO-stearic acid, however, seems to alter the entire course of the reaction. Both the crosslink formation and TMTD decomposition are much higher in presence of ZnO or ZnO-stearic acid, but stearic acid seems to have no effect. The reaction mechanisms for TMTD accelerated sulfuration in absence and presence of ZnO have also been studied.
Sulfenamide Accelerated Sulfur Vulcanization of Natural Rubber in Presence and Absence of Dicumyl Peroxide
Authors: Manik S. P. , Banerjee S. 
Published: February 2011

Abstract
Sulfuration by CBS acceleration both in presence and absence of ZnO and stearic acid with or without DCP has been studied in detail. It is observed that CBS increases the rate of DCP decomposition and decreases the crosslinking maxima due to DCP—ultimately leading to zero cross links with high amounts of CBS. In accordance with the observed sulfur decrease, free MBT formation, combined sulfur as MS etc., a predominantly radical mechanism has been presented, presumably not proceeding through intermediate complex formation. In mixes containing DCP together with sulfur, CBS, ZnO, and stearic acid crosslinks are found to be formed nearly additively, further confirmed by methyl iodide treatment of vulcanizates. Attempts have been made to interpret the results in terms of radical and polar mechanisms.
Mechanism of Protection against Ozone by N-Phenyl-N′-Isopropyl-p-Phenylenediamine
Authors: Razumovskii S. D. , Batashova L. S. 
Published: February 2011

Abstract
A number of hypotheses about the mechanism of action of anti-ozonates (AOZ) was verified by experiment. Films and solutions of polybutadiene, and also its mixtures with a model olefin, containing N-phenyl-N′-isopropyl-p-phenylenediamine (PIPP), showed that the ozone reacted first with the PIPP. Kinetic curves of ozone penetration during its reaction with PIPP were plotted at −78° C in solution and the relative reaction rate was determined. PIPP-ozone reaction products were found to contain nitroxide radicals.
The Migration of Extender Oil in Natural and Synthetic Rubber. IV. Effect of Saturates Geometry and Carbon Black Type on Diffusion Rates
Authors: Corman B. G. , Deviney M. L. , Whittington L. E. 
Published: February 2011

Abstract
Migration of oils, curatives, antioxidants, and other compounding materials in a vulcanized rubber matrix is a general phenomenon. A continuing, long range program has been undertaken in these laboratories to understand better this effect, in order that ultimately the compounder can predict, from a knowledge of the molecular nature of the penetrant and the physico-chemical properties of the cured matrix, the distribution of the various components during the service life of the finished rubber product. A sensitive radiotracer approach with earbon—14 is being used to study this system. Earlier work in this program has established the general value of the diffusion coefficient for whole paraffinic oils and for aromatic oils and their fractions. In general, this has shown that moderate variations in the molecular composition of the aromatic portions of the oils have only minor effects on these migration rates. Using similar computer derived diffusion coefficients, the current data indicate that naphthenic molecules migrate at equal to slightly higher rates than aromatic molecules of similar boiling points. Thermal diffusion as a mode of separation of the oil gives fractions showing more selectivity (larger differences in migration rates) than the formerly used silica gel procedures. Variations in carbon black type and loading levels have no detectable effect on migration. The most important factor in diffusion is the polymer matrix, which for the oils studied is in the order : polybutadiene (D≃6.4×10−7 cm2 sec−1 at 100° C), natural rubber (D≃3.5×10−7 cm2 sec−1), ethylene-propylene-diene rubber (D≃2.6×10−7 cm2 sec−1) and styrene—butadiene rubber (D≃1.9×10−7 cm2 sec−1). Activation energies for the diffusion process were PBR, 3.1 ; NR, 7.8; EPDM, 10.3; and SBR, 9.9 (energies in kilocalories per mole).
The Physico-Chemical Characteristics of Commercial Elastomers. I. Molecular Dimensions and Distribution Functions of Polybutadienes
Authors: Curchod J. 
Published: February 2011

Abstract
Without claiming that the comparison of the physico-chemical properties of commercial polybutadienes has been entirely satisfactory, we do think that the method of investigation used, with the essential details given, would be of use for any other type of elastomer. This method allowed a comparison of 14 different samples and the determination for each of the principal molecular parameters ([η] ,Mw) as well as the distribution functions. Even if the results have sometimes been incomplete or imprecise we do hope to have rendered a service to the manufacturers and users of these elastomers, which was after all the essential goal of this study. This article represents only a part of the results obtained. For reasons of volume we have had to defer until a later article the examination of the [η] /M relationship, the comparison of the unperturbed dimensions and their correlation with structure, certain theoretical considerations of the virial coefficients, and the presence of branching.
Molecular Weight Distribution of Polystyrene and of Butadiene-Styrene Copolymers Prepared in Emulsion Systems
Authors: Uraneck C. A. , Burleigh J. E. 
Published: February 2011

Abstract
Polystyrene and butadiene—styrene copolymers (SBR) were parepared in emulsion systems with a homologous series of commercial mercaptan modifiers. The molecular weight distribution (MWD) of the sets of polymers changed in a consistant manner when the regulating index of the mercaptan was relatively low. However the shape of the MWD curves appeared distorted in comparison to theoretical curves when the modifier depleted rapidly and when divinyl-benzene was present in the system. The divergence from the theoretical curve is attributed to a higher degree of branching in the high molecular weight fractions. Differences in MWD of SBR made with n- and tert-dodecyl mercaptans was marked. Notable differences were also found for SBR 1500 samples from the industry at random, but only slight differences were seen in a set of SBR 1503 samples. This study shows how the MWD of polymers prepared in emulsions can be varied simply by use of modifiers with different regulating indexes.
Theoretical and Experimental Values of the Volume Changes Accompanying Rubber Extension
Authors: Christensen R. G. , Hoeve C. A. J. 
Published: February 2011

Abstract
The molecular theory of rubber elasticity assumes the free energy to consist of two parts: a liquidlike free energy that is governed by intermolecular interactions and is independent of strain at constant volume and an intramolecular interaction free energy equal to the sum of the free energies of the chains making up the network. The volume increases of rubber samples as a function of their length were found to be considerably larger than predicted by the molecular theory. Therefore, contrary to common belief, the values of (∂E/∂L)V,T might not be related solely to changes in intramolecular interactions with extension. Also, the usual procedure to obtain values of (∂E/∂L)V,T from measurements of (∂f/∂T)p,L with the aid of the molecular theory is not correct.
An Apparatus to Measure the Dynamic Mechanical Properties of Solid Polymers
Authors: Shroff R. N. , Livingston D. I. , Fielding-Russell G. S. 
Published: February 2011

Abstract
An apparatus designed to measure the tensile storage modulus E′ and tensile loss modulus E″ for rubbers and plastics over a broad temperature range (ca. − 100 to + 150° C) and over two decades of frequency is described. One end of a narrow rectangular strip of the specimen is sinusoidally displaced at small amplitude in the direction of its thickness. The theoretical considerations are given for deriving the dynamic parameters E′ and E″ from the force F measured at the other end of the sample and the phase angle ϕ by which the force leads the driving amplitude Ad. The instrument is distinctive in that the phase angle is measured rapidly and accurately with a rotary variable differential transformer. The use of the instrument is illustrated with results obtained on three polymer vulcanizates : trans 1,4-polypentadiene, an acrylonitrile-butadiene copolymer, and a blend of acrylonitrile—butadiene copolymer with poly (vinyl chloride). The equation of Williams, Landel, and Ferry satisfactorily described the temperature dependence of the shift factors obtained from the plots of E′ and E″ as a function of log frequency.
Methods for the Determination of Internal Energy Contribution to Rubber Elasticity
Authors: Tanaka T. , Yokoyama T. , Yamaguchi Y. 
Published: February 2011

Abstract
In order to determine exactly the contribution of internal energy component to retractive force (fe/f), two methods (one is Single Specimen Method [Successive Contraction Method] and the other Multi Specimen Method), two different reference lengths (one is the initial length of undeformed specimen and the other the final length including permanent set), and two instruments of different type (one is automatic balance type relax-o-meter [ROM] and the other tensile tester) were examined by using natural rubber, cis-1,4-polyisoprene, and polyurethane rubber. The apparent mechanical and thermo-dynamic properties were significantly dependent upon these methods and reference lengths. In spite of the variation of C1 and C2 in Mooney-Rivlin plot, fe/f was almost unaffected and the sign of this value coincided with that expected from the chain conformation as far as ROM-Single or Multi Specimen Method and the final length were adopted. The influences of permanent set, the time used to attain equilibrium, etc. were also discussed.
Crystallization of Cis-Polyisoprenes in a Capillary Rheometer. II. The Effects of Experimental Parameters and Molecular Structure
Authors: Folt V. L. 
Published: February 2011

Abstract
Cis-polyisoprenes are readily crystallized under the pressure and orientation forces existing in a capillary rheometer. The ease at which crystallization can be effected is a complex function of the interrelationships existing among the temperature, the molecular weight, stereoregularity, and the dimensions of the capillary. For a given cis-polyisoprene and capillary, crystallization occurs more readily as the molecular weight is increased. Decreasing the diameter of the capillary and/or increasing the length of the capillary enhances the ease at which a given cis-polyisoprene can be crystallized. Using the optimum conditions presently available, natural rubber has been crystallized at 146° C. The ease at which crystallization is effected decreases drastically as the cis-1,4 content of the polyisoprene is reduced. Trans-1,4 and 3,4 are similarly effective in retarding the crystallization process and their effects are proportional to their concentrations in the molecular chains. However, polyisoprenes which will not crystallize under static conditions at −20° C are readily crystallized in the capillary rheometer at much higher temperatures.
Crystallization of Cis-Polyisoprenes in a Capillary Rheometer. I
Authors: Folt V. L. , Smith R. W. , Wilkes C. E. 
Published: February 2011

Abstract
Natural rubber is readily crystallized under the pressure and orientation forces existing in a capillary rheometer. The crystallization of natural rubber is readily effected over the temperature range covering commercial processing and fabricating temperatures. The crystalline rubber is stable at atmospheric pressure and room temperature. The observed crystalline melting point increases with increasing crystallization temperatures. Wide angle x-ray pictures show the crystals to be highly oriented in the direction of flow. Electron micrographs of fracture surfaces of the crystalline rubber show the existence of a very complex morphology. Where the degree of orientation is highest, a fibrillar structure is observed parallel to the direction of flow. The fibrillar structure changes to a shish-kebab structure about midway down the capillary. Apparently, a regrouping occurs with chain folded lamellae forming at right angles to the oriented fibrillar type crystals. A rotation of the chain-folded lamellae may occur as the exit end of the capillary is approached.