bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Load Dependence of Laboratory Abrasion and Tire Wear
Authors: Grosch K. A. , Schallamach A. 
Published: February 2011

Abstract
The first outcome of this investigation is that non-proportionality between sliding abrasion and load has relatively little effect on the load dependence of tire wear, which is almost entirely governed by the load dependence of the contact length, unless the inflation pressure is very low. The modified theory on the wear of slipping wheels predicts near proportionality at constant slip between wear in crab walk and side force. This relation is useful for test procedures and has been qualitatively confirmed by experiment. The theory suggests, furthermore, the existence of a severity effect on tire wear ratings which is independent of ambient or tire temperature and is expected to affect the wear rating of different tires if road tests are carried out on test routes with radically different surface topology.
Effect of Finite Extensibility on the Viscoelastic Properties of a Styrene-Butadiene Rubber Vulcanizate in Simple Tensile Deformations up to Rupture
Authors: Smith T. L. , Dickie R. A. 
Published: February 2011

Abstract
Stress-strain and rupture data were determined on an unfilled styrene-butadiene vulcanizate at temperatures from −45 to 35° C and at extension rates from 0.0096 to 9.6 min−1. The data were represented by four functions: (1) the well-known temperature function (shift factor) aT; (2) the constant-strain-rate modulus, F (t, T) reduced to temperature T0 and time t/aT, i.e., T0F (t/aT)/T (3) the time-dependent maximum extensibility λm (t/aT); and (4) a function Ω(χ) where χ=(λ−1)λm0/λm, in which λ is the extension ratio and λm0 is the maximum extensibility under equilibrium conditions. The constant-strain-rate modulus characterizes the stress-time response to a constant extension rate at small strains, within the range of linear response; λm is a material parameter needed to represent the response at large λ; and Ω(χ) represents the stress-strain curve of the material in a reference state of unit modulus and λm=λm0. The shift factor aT was found to be sensibly independent of extension. At all values of t/aT for which the maximum extensibility is time-independent, the relaxation rate was also found to be independent of λ. These observations indicate that the monomeric friction coefficient is strain-independent over the ranges of T and λ covered in the present study. It was found that λm0=8.6 and that the largest extension ratio at break (λb)max is 7.3. Thus, rupture always occurs before the network is fully extended.
Stiffness of Molecular Chain of Synthetic Rubber
Authors: Furukawa J. , Yamashita S. , Kotani T. , Kawashima M. 
Published: February 2011

Abstract
The principal polarizabilities of rubber molecules, including copolymers, were evaluated by the arithmetic sum of the polarizabilities of the components. The mean polarizabilities thus calculated are in good accordance with those from the refractive indices. The anisotropic polarizabilities of polymeric units for several kinds of rubbers were calculated and compared with those estimated from stress-optical coefficients. Length or molecular weight of a statistical link thus estimated is used as a measure of stiffness of rubber molecules. There is a good accordance in statistical links between anisotropy and viscosity measurements in a theta solvent. The molecular weight or length of a statistical link thus obtained is found to be compatible with the value calculated from the end-to-end distance in a theta solvent. The ultimate elongation of rubber is correlated with the stiffness and can be estimated from the measure of stiffness of the chain.
The Study of Polymers by High-Temperature ATR Spectroscopy
Authors: Fujimoto K. , Wataya K. 
Published: February 2011

Abstract
A new high-temperature attenuated total reflectance apparatus (HATR) was constructed and used at different temperatures for making infrared measurements on the same liquid or solid sample. It was found that this method was applicable to the continuous quantitative analysis of changes occurring during chemical reactions such as polymerization, isomerization, and crosslinking. In the bulk polymerization of styrene, the process of monomer consumption could be followed progressively. In the crosslinking reaction of high cis-polybutadiene by sulfur-accelerator or peroxide crosslinking systems, the decrease of cis content and its partial isomerization to trans structure was measured. Furthermore, in the cross-linking reaction of ethylene-propylene terpolymers (EPDM), the consumption of double bonds was observed over the course of the reaction with both sulfur-accelerator and peroxide crosslinking systems. The effect was greatest in the case of methylenenorbornene-type EPDM.
Dependence of Relative Volume on Strain for an SBR Vulcanizate
Authors: Fedors R. F. , Landel R. F. 
Published: February 2011

Abstract
Volume-extension data for an SBR-peroxide vulcanizate are presented. It is shown that Gee's expression, in conjunction with the experimental stress-strain response for the vulcanizate, leads to a volume-extension expression which describes the experimental data.
Multicomponent Polymerization. I. Integration of the Rate Equations
Authors: O'Driscoll K. F. , Knorr R. 
Published: February 2011

Abstract
The equation describing instantaneous copolymer composition in free radical vinyl copolymerization has been known and verified for many years. Although this equation has been integrated to give composition as a function of conversion, no analytical expression has been presented which gives conversion as a simple function of time. In this paper a derivation and experimental verification of such an equation is presented. Applications to problems in copolymerization kinetics are also considered. Extension of the equation to systems of more than two monomers is postulated.
The Control of Copolymer Distributions in Batch and Tubular Reactors
Authors: Ray W. H. , Gall C. E. 
Published: February 2011

Abstract
In this paper, the problem of maintaining a specified copolymer composition distribution in a batch reactor is considered. The advantages of temperature control, rather than monomer addition are discussed, and the necessary and sufficient conditions for temperature control in the face of monomer depletion are derived. Examples are worked to illustrate the results for a practical range of temperatures.
Application of Viscoelasticity to the Processibility of Elastomers
Authors: Kontos E. G. 
Published: February 2011

Abstract
The processibility of elastomers can be studied systematically by splitting up the process into component unit operations. By applying the theories of applied mechanics and taking into consideration the viscoelastic nature of raw rubbers modest theoretical progress has been made in predicting and correcting processing deficiencies. Important viscoelastic properties affecting the rheological behavior of rubbers have been identified. The existing relationships between macromolecular structure and the important viscoelastic properties have been presented for several synthetic rubbers. The dependence of some unit operations such as milling, calendering, and building on maximum relaxation time and viscosity has been demonstrated.
A Digital Computer Program for Compound Optimization
Authors: Beaumont R. A. , Hartmann N. E. , Chamberlain C. M. 
Published: February 2011

Abstract
In recent years the advent of computers has allowed the analysis of result of far more sophisticated experiments than was possible by manual methods and this has encouraged rubber compounders to investigate the effect on properties of changing many compound variables simultaneously. By using appropriate experimental designs, then fitting property response equations to the data by regression techniques, it is possible to predict the properties of any compound within the experimental range considered. Given a set of response equations describing all the properties of interest in terms of the levels of compound variables, optimization of the compound becomes the problem of “—the determination of the ‘best’ set of factor combinations or design variables consistent with specified constraints”.
Impact Polystyrene: Factors Controlling the Rubber Efficiency
Authors: Wagner E. R. , Robeson L. M. 
Published: February 2011

Abstract
The rubber phase volume (rubber + occluded polystyrene) can be widely varied in impact polystyrene by controlling the rate of agitation during polymerization. The tensile modulus and magnitude of the rubber phase mechanical loss transitions are related to the degree of polystyrene occlusion. It is shown that the occluded polystyrene can substitute for rubber in determining these parameters. Impact strength and ultimate elongation pass through maxima as the rubber phase volume is increased at constant rubber concentration due to the optimization of rubber phase volume with particle size and rubber phase modulus. Over crosslinking of the rubber and a high concentration of a low molecular weight tail of matrix polystyrene have deleterious effects on the impact strength and ultimate elongation. The optimization of these three factors is required in making efficient use of the rubber in impact polystyrene.
Monomer Sequence Distribution in Butadiene Styrene Copolymers
Authors: Mochel V. D. , Johnson B. L. 
Published: February 2011

Abstract
A method is described for determining styrene sequence distribution in butadiene-styrene copolymers. An analog computer is used to resolve overlapped peaks in the styrene aromatic proton NMR spectrum. In n-BuLi copolymers a quite quantitative distinction can be made between “short” sequences, containing two and three styrene units, and “long” sequences, containing more than three units. With this method it is possible to determine experimentally the styrene-centered triad distributions and approximate styrene sequence distributions of butadiene—styrene copolymers. Agreement between calculated and NMR-curve analysis results is good, especially for n-butyllithium-catalyzed butadiene—styrene copolymers.
Prevulcanization Inhibitor the Chemistry of Scorch Delay
Authors: Leib R. I. , Sullivan A. B. , Trivette C. D. 
Published: February 2011

Abstract
Sulfenamide accelerators serve to perform two functions. They provide the necessary time period required to mix, process and shape rubber compounds. This portion of the overall vulcanization process is usually referred to as scorch delay. In addition, sulfenamides function as accelerators, in that once the crosslinking process has begun, they speed up this reaction. The delay period occurs because the sulfenamide must be converted to polythiobenzothiazoles, the precursors to crosslinking, before crosslinking can take place. The overall reaction of sulfenamide with sulfur is an autocatalytic process with MBT the autocatalyst. The role of PVI in this scheme is to remove MBT from this autocatalytic sequence of reactions, thus delaying those reactions which preceed crosslink formation.
Ozone Cracking and Protection of Rubber
Authors: Lake G. J. 
Published: February 2011

Abstract
Studies of the growth of single ozone cracks show that a critical severity of deformation is required for growth to occur. Above this deformation the rate of single crack growth is essentially independent of strain and for a number of rubbers at normal temperatures is proportional to the ozone concentration. The mechanics of cracking in stretched surfaces is more complex, the rate of growth being dependent on strain and on various other factors such as the gas flow conditions and the test piece size. It is shown that these effects are consistent with diffusion control of the rate of attack; this occurs because the rapidity with which ozone is destroyed by stretched rubber leads to a reduced concentration adjacent to a surface. Certain chemical antiozonants can completely prevent cracking, even at very high deformations. Current investigations suggest that this is due to the formation of a protective layer on the surface of the rubber by direct reaction of the antiozonant with ozone; the diffusion of unreacted antiozonant is an important factor influencing layer development. It appears that the amount of antiozonant required for protection may be determined by the rate at which a coherent layer can be formed in relation to the rate at which ozone is attacking the surface.
A Comparative Study of the Processing and Properties of Natural and Synthetic Polyisoprene Rubber Latex
Authors: Gorton A. D. T. 
Published: February 2011

Abstract
A comparison of natural polyisoprene latex with that of synthetic polyisoprene latex included latex properties, raw latex films, compound stability and processing, prevulcanization, vulcanizate properties, foam rubber, dipping, and adhesives. A number of differences were seen between the two latexes. It is obvious that synthetic polyisoprene latex is a very different latex to its natural counterpart. In many properties in the wet and dry state, raw or vulcanized, the synthetic latex shows inferior properties to that of natural latex. The unique combination of the polyisoprene rubber phase and the stabilizing system of protein/fatty acid soap in natural rubber latex concentrate make it superior in processing and properties to the synthetic polyisoprene latex. Many of the published claims for the synthetic material failed to receive experimental support in this study.
Particle Interaction in Carbon Black Loaded Vulcanizates
Authors: Voet A. , Cook F. R. , Hogue R. 
Published: February 2011

Abstract
Mixtures of SBR and a carbon black were swollen in a nonvolatile hydrocarbon and vulcanized thereafter. The swelling agent was removed by extraction with a volatile solvent in successive steps, thus producing a series of isotropically shrunken vulcanizates. Dynamic modulus values at greatly varying amplitudes were determined for vulcanizates with high and medium structure HAF carbon blacks. Results indicate that the transient carbon black structure is an exponential function of the interparticle distance, confirming a previous hypothesis attributing the transient structure to a mutual particle attraction by van der Waals forces.
Physics of the Slipping Wheel. III. Slip under Camber and Other Forces in Pneumatic Tires
Authors: Livingston D. I. 
Published: February 2011

Abstract
An elementary theory is proposed for the origin of the camber force arising when the plane of a traveling wheel is inclined to the vertical and for its interaction with the lateral slip force when the wheel is at an angle to its traveling direction. The theory considers the path of the periphery of the wheel through the ground contact to be deflected from that taken if the wheel were undeformed, and the resulting tangential stress is summed over the contact area. The results are consistent with experiment for small camber angles.
Determination of Butadiene in SBR-Type Copolymers by Thermographic Analysis
Authors: Sircar A. K. , Voet A. 
Published: February 2011

Abstract
Thermograms of SBR-type elastomers obtained by differential scanning calorimetry in an inert atmosphere, permit the evaluation of the butadiene content of the elastomers by means of determination of the area per unit weight under the exothermic part of the curve.
Characterization of Sulfur-Cured Styrene-Butadiene Copolymer Rubbers and Their Polybutadiene Blends
Authors: Clark J. K. , Scott R. A. 
Published: February 2011

Abstract
Dissolution of sulfur-cured, carbon black-loaded copolymers and their blends with cis-1,4-polybutadiene (PBD) are brought about by boiling with o-dichlorobenzene which contains a small amount of 2,2′-dibenzamidodiphenyl disulfide. The resulting slurries are subjected to a sequence of separations which include high-speed centrifugation to remove solids, and solvent precipitation followed by filtration to isolate the precipitates. The precipitates are washed with solvent to remove soluble organic materials followed by carbon disulfide washing to dissolve the polymers. Cast films of the polymers are obtained by evaporating the carbon disulfide washings onto sodium chloride discs. The infrared spectra of the cast films of these preparations are very similar to those of their respective polymers prior to loading and curing. Calculations for relative concentrations of bound styrene and PBD micro-structures permit nominal identification of the kinds of styrene-butadiene rubber and the amounts of cis-1,4-PBD used in a cured rubber formulation. Absorption bands used are near 3.35 μ for cis-1,4-PBD, 6.65 μ for bound styrene, 10.35 μ for trans-1,4-PBD; and 11.0 μ for vinyl-1,2-PBD. Efforts are being made to improve the data by using a grating infrared instrument and also to extend the calibrations to include other rubber blends.
Characterization of Elution Chromatography Fractions from CIS-Polybutadiene by GPC
Authors: Smith W. V. , Thiruvengada S. 
Published: February 2011

Abstract
A preparative fractionation of about 23 g of a commercial cis-polybutadiene rubber is described. The method employed was a solvent elution chromatographic method with very little temperature gradient. The molecular weight distributions of the fractions obtained were determined by an analytical fractionation of 20 mg of polymer. The method was similar to the preparative fractionation and involved solvent elution chromatography. The fractions obtained were assayed for quantity, molecular weight, and molecular weight distribution by GPC. The low molecular weight fractions of the preparative fractionation had molecular weight distributions which could be closely approximated by two log normal distributions, the low molecular weight component having the narrower width. The ratio of weight to number average molecular weight was found to be about 1.1 for these samples. The higher molecular weight fractions could also be approximated by two log normal distributions; however, in these fractions the low molecular weight component had a very broad distribution but constituted only a small portion of the sample. The widths of the GPC curves of the fractions correlate satisfactorily with the molecular weight distributions found by the analytical refractionations. The GPC width is a sensitive criterion of the width of the molecular weight distribution even when only two columns are used. It is felt that the analytical fractionation procedure presented gives more detailed information on the molecular weight distribution than is easily obtainable from an ordinary GPC curve.
Outstanding Practical Problems in Emulsion Polymerization with Particular Reference to Dienic Hydrocarbons
Authors: Duck E. W. 
Published: February 2011

Abstract
The incentives and problems associated with 100% conversions of polymerization are discussed with reference to the heterogeneity produced by emulsion polymerization of styrene-butadiene rubbery copolymers. Stereospecific problems are also considered together with the influence of latex particle size and particle size distribution on viscosity and solids content and film-forming properties.
Multiple Glass Transitions in Butadiene-Acrylonitrile Copolymers
Authors: Chandler L. A. , Collins E. A. 
Published: February 2011

Abstract
The second order transition temperatures (Tg) have been determined for a range of compositions of polybutadiene-acrylonitrile copolymers. It was found that copolymers having more than 36 per cent acrylonitrile had a single Tg while copolymers with less than 36 per cent acrylonitrile had two main Tg's. The analyses were carried out with differential thermal analysis (DTA). The two Tg's are interpreted as the result of incompatible phases which differ in BD and VCN ratio. The presence of two phases is discussed in terms of polymerization conditions and molecular structure.
Effect and Detection of Loose Chain Ends in Crosslinked Polyurethane Elastomers
Authors: Oberth A. E. 
Published: February 2011

Abstract
The effect of loose chain ends on tensile properties and equilibrium swelling of crosslinked polyurethane rubbers is studied. As in plasticized elastomers, tensile strength and elastic modulus are reduced approximately by a factor (1−νE,P)2, where νE,P is the volume fraction of loose chain ends, plasticizer, or both. This effect is much larger than predicted by present theory. Also the equilibrium volume swelling ratio, V0/V, of rubbers having terminal chains or an equal volume of plasticizer is the same, provided they do not differ in crosslink density. However, the volume fraction of “network rubber” in the equilibrium swollen specimen, ν2, differs owing to the non-extractability of terminal chains. On this basis a method is proposed which allows experimental determination of the volume fraction of loose ends. Elastomers abounding in loose chain ends show markedly less long term stress relaxation. This effect is not clearly understood but is useful to detect the presence of non load-bearing network.
A Carbon Black Structure-Concentration Equivalence Principle. Application to Stress-Strain Relationships of Filled Rubbers
Authors: Kraus Gerard 
Published: February 2011

Abstract
It is shown that various modulus values of carbon black reinforced rubber are functions of the product of the actual black loading and a structure dependent factor. The structure factor appears to be a linear function of the so-called 24M4 value of the dibutylphthalate absorption and is independent of elongation, temperature, and degree of cross-linking over the ranges covered by the data reported. An interpretation of the results is offered based on the idea of polymer occluded in the interstices of primary structure aggregates and thereby shielded from deformation. Structure-concentration equivalence can only be demonstrated with carbon blacks differing in (primary) structure alone. Deviations are observed whenever the carbon blacks compared vary significantly in specific surface area and surface chemical activity.
Crystallization of Cis-Polyisoprenes in a Capillary Rheometer. III. The Effects of Certain Additives
Authors: Folt V. L. 
Published: February 2011

Abstract
Cis-polyisoprenes are readily crystallized under the pressure and orientation forces existing in a capillary rheometer. Oil-extension retards the rheometer crystallization process. However, natural rubber/oil blends containing up to 50 phr of oil are readily crystallized above room temperature. The retardation effect of oil-extension is not nearly as drastic as that produced by slight alterations in the stereoregularity of the polymer chains. ISAF carbon black significantly enhances the ease at which solidification of the melt can be effected in the capillary. Aging the black/rubber mix at room temperature enhances the ease of solidification. Shearing the aged black/rubber mix results in a retardation of the solidification process but subsequent aging of the sheared mix again enhances the ease of solidification in the capillary. Acetone extracted natural rubber crystallizes more easily in the capillary rheometer than the non-extracted material; a behavior in marked contrast to that observed under static conditions at −20° C where removal of the acetone solubles from natural rubber retards the crystallization process. A brief discussion of the crystallization mechanism in terms of supermolecular flow units is presented.