bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lubricated Friction of Rubber. II. Interaction of Rubber and Sliding Surfaces
Authors: Percarpio E. P. , Bevilacqua E. M. 
Published: February 2011

Abstract
Skid resistance of tires on wet pavements in an important component of tire safety; it is important to evaluate it precisely under conditions which are pertinent to actual use. The closest approximations to practical conditions are provided by measures of side force coefficient or by locked wheel sliding, both of which are related to problems of vehicle control. However, both of these require that a test vehicle be provided with four identical tires, that a surface large enough to test on be available, and that all test conditions including the nature of the surface be reproducible. For any rational program of research, costs of comparing materials of tire and of road would mount astronomically unless a controlled laboratory test were available which is well correlated with field experience, so that many variables can be studied conveniently in the laboratory. Such a test is available in the applications of the Portable Skid Resistance Tester. Results with this apparatus have been shown to correlate well with those from tests of vehicles on roads over a range of road properties, correlations apparently being with properties of a patterned tire. The results have been further shown to be well correlated with accident statistics. This report will show that correlations with tests on vehicles are valid over a wide variation in rubber properties as well.
Lubricated Friction of Rubber. V. Influence of Rubber Resilience and Hardness on Friction
Authors: Percarpio E. P. , Bevilacqua E. M. 
Published: February 2011

Abstract
The dominant importance of hysteresis in lubricated friction of rubber was first outlined by Tabor and has been extensively confirmed since. A number of workers have also shown that dry friction is correlated with hysteresis, but the mechanistic connection is still unclear. Rubber hardness has been less definitely correlated with friction. This may result in part from the choice of surface on which to test the rubber compositions studied. We have previously shown the importance of the test surface and recommended use of wavy glass to simulate actual slippery roads in lieu of a representative road surface. Carr reported our finding that the relative influence of rubber hardness depends on the texture of the hard surface on which it slides. Using the wavy glass and a slippery road surface, we have now studied a very wide range of compositions, both gum and filled, derived from commonly used tire rubbers, as well as others included to extend the range of properties studied. These results fully confirm the importance of hysteresis and more clearly define that of hardness. These two properties together almost completely determine wet friction on slippery roads. Most of the variance not accounted for is attributable to measurement error.
Lubricated Friction of Rubber. VII. Notes on a Standard Tire and Procedure for Skid Testing
Authors: Bevilacqua E. M. , Percarpio E. P. 
Published: February 2011

Abstract
In an effort to achieve uniformity in testing and reporting skid resistance as a necessary preliminary to attempts to make improvements in roads on a rational basis, cooperative efforts have been underway over the past several years to standardize apparatus and equipment. One part of this effort has been the designation of a standard tire (ASTM E249-64T) for skid resistance testing. At the time this standard was set up important factors in skid resistance were not fully known and a composition was chosen on the basis that it was representative of actual tread stocks which have been used and had skid resistance shown by experience to be satisfactory. We have recently described evidence that the skid resistance of tires on real roads can be described absolutely in terms of properties of the tread stock which can be measured readily in the laboratory. In the course of this work we have further found evidence that the proposed standard tire is not as sensitive to variation in properties of the road as others which might be used. We have also shown that important properties of the road surface can be measured without a priori knowledge of the character of the road by the use of more than one rubber composition at the same location. Finally, we have observed that speed sensitivity of friction on road surfaces can be determined by low speed measurements. This report is therefore written to suggest that consideration be given to revision of procedures currently in view to take advantage of advances in our present state of knowledge. Since the recommendations constitute a substantial departure, they are not set forth here in specific detail, but their basis presented for consideration.
Lubricated Friction of Rubber Discussion
Authors: Kummer H. W. 
Published: February 2011

Abstract
The authors have presented a comprehensive and timely review of the likely friction mechanisms of rubber, sliding on lubricated surfaces. They have also advanced several new ideas which should stimulate workers in the field and which might affect the, selection of rubber sliders and test tires for routine pavement friction testers. Since their introductory paper summarizes the principal data and thoughts, presented in papers II to VII, the discussion refers, with one exception, to paper I only. I would like to particularly touch upon : (a) The significance of skidding accident data in their various forms of presentation. (b) Minimum required friction levels to prevent skidding during all “normal” vehicle maneuvers. (c) Friction transients of pavement surfaces at the onset of rain. (d) The existence or nonexistence of adhesion and the relative frictional contribution made by abrasion. (e) The relative merits of portable devices and skid trailers, intended for routine operation in the field.
Method of Determining Damping and Elastic Properties of Rubber Used in Tires
Authors: Moore D. F. , Larson D. B. 
Published: February 2011

Abstract
Dynamic penetration of tread rubber by asperities of a roadbed for a rolling tire was simulated by impact of a rubber specimen on different arrangements of small spheres. The penetration history of the draping rubber was then analyzed to determine its damping and elastic properties. The method of analysis essentially varied two parameters in a nonlinear differential equation that described the system, so as to minimize the error between the integrated equation and test data. Least square of minimization was used. The results indicated that the viscoelastic behavior of the rubber can be represented by a simple Voigt model. The importance of jointly considering both draping and traction zones in the contact patch of a rolling tire is discussed.
Origin of Tire Squeal. II. Tire Squeal Calculation from Materials Properties
Authors: Trivisonno N. M. , Beatty J. R. , Miller R. F. 
Published: February 2011

Abstract
In the first paper of this series, the origin of tire squeal was studied with reference to the location of the vibrating elements and the measurement of their motion. This paper approaches the problem of the relationship of materials properties to tire squeal. A simplified picture of tire squeal leads to the equation of motion of a vibrating tread element. The squeal theory, which takes into account hardness and resilience as measured by dynamic modulus and loss tangent of the material at the squeal frequency, and also the frictional properties of the tread compound as a function of sliding velocity, treats tire squeal as a relaxation oscillation of the tread in shear. The theory determines a squeal trajectory under any given conditions by solving the equation of motion for the sliding tread in contact with the road. The squeal trajectory gives the frequency, displacement amplitude, and velocity amplitude of the squeal oscillation. The simplified theory was checked by a comparison of theoretical and experimentally measured squeal frequencies and intensities on fifteen different tread compounds with widely varying physical properties. It was shown that tire squeal intensity depends primarily on hardness of the tread compound, with harder compounds squealing more. Yerzley resilience has a lesser effect, lower resilience compounds tending to squeal less.
Stiffness of Cord and Rubber Constructions
Authors: Gough V. E. 
Published: February 2011

Abstract
When the function performed by pneumatic tires in guiding vehicles by development of cornering force was first studied many years ago, a number of attempts at analysis were based on the concept that cornering force was developed primarily because of cross-bias construction. None of these attempts provided either a satisfactory or fruitful basis of analysis. Later, adequate guiding properties developed by experimental spring wheel designs when rubber was in short supply (1940–45) indicated that the cross-bias construction was not essential for cornering forces. Designs involving flexible but edgewise rigid belts or tracks were very successful in this regard. Analysis of these structures turned attention to the elastic beam on elastic foundation concept of a tire, not only for radial load carrying capacity but also for lateral and cornering properties. However, consideration as to where in the shoulder region the casing was to be taken as part of the beam and where it was to be considered part of the foundation, proved to be a stumbling block when considering a conventional tire. Development of the tire with radial ply casing and a rigid breaker band resolved this point by providing a tire where the ambiguity did not exist. In subsequent investigations the ambiguity for the cross-bias tire was resolved with measurements by the same experimental procedures at corresponding points on the tread band and discussing the tire in terms of effective stiffnesses.
Crosslinking Reaction of Rubber with Aldehydes
Authors: Minoura Y. , Tsukasa M. 
Published: February 2011

Abstract
The reactions of rubber with aldehydes have previously been studied in latex or in solutions and the reaction products formed by cyclization, condensation, or addition, have been reported. In the present study, solid-state reactions of rubber with aldehydes were carried out. It was found that crosslinked rubbers may be obtained by press curing in the presence of aldehydes with acidic catalysts. Poly-chloroprene and Hypalon especially undergo these reactions without a catalyst or with a small amount of catalyst. In the experiments using various aldehydes, some improvements in the properties of the crosslinked rubber were observed when aldehydes such as paraformaldehyde or α-polyoxymethylene were used. Some Lewis acids such as SnCl2·2H2O were found to be more effective catalysts than the above, and it was found that organic acids such as p-toluenesulfonic acid could also be used. The curing seemed to be an ionic reaction. The physical properties of the crosslinked rubber are similar to those of sulfur-cured rubbers.
Structural Characterization of Vulcanizates Part X. Thiol-Disulfide Interchange for Cleaving Disulfide Crosslinks in Natural Rubber Vulcanizates
Authors: Campbell D. S. 
Published: February 2011

Abstract
The thiol-disulfide exchange reaction is shown to be applicable to cleavage of disulfide crosslinks in accelerated sulfur vulcanizates of natural rubber. The reaction, in conjunction with the previously reported selective cleavage of polysulfide crosslinks, is used to determine the distribution of crosslink types for several accelerated sulfur vulcanization systems as a function of cure time. Discrepancies between the results and published results obtained using the reagent sodium di-n-butyl phosphite for disulfide crosslink cleavage are discussed.
Stress Relaxation of Natural Rubber During Irradiation
Authors: Evans D. , Morgan J. T. , Sheldon R. , Stapleton G. B. 
Published: February 2011

Abstract
The site of chain scission and crosslinking in vulcanized natural rubber irradiated with 4 MeV electrons has been determined by analysis of stress relaxation data. Sulfur and peroxide vulcanizates of different crosslink densities were prepared and the crosslink densities determined from stress—strain measurements. Stress relaxation was measured during irradiation using modified commercial relaxometers. The specimens were maintained in an atmosphere of nitrogen to minimize oxidative side effects. Scission is deduced to take place in the vicinity of crosslinks, since the rate of continuous stress relaxation is independent of crosslink density. Scission may be associated both with crosslinks initially present and with those subsequently introduced by irradiation. Crosslinking by radiation is largely a random process. However, there is a crosslinking reaction dependent to a slight extent on crosslink density as well as a small contribution from random scission reactions. G values for the random reactions are given.
Degradation of Highly Elastic Polymers
Authors: Scheele W. , Hillmer K.-H. 
Published: February 2011

Abstract
The inhibited autooxidation of 1,5-polyenes was studied by means of intermittent relaxation in oxygen, using natural rubber crosslinked by C—C links. The frequency and temperature conditions were so chosen that no degradation would have taken place in nitrogen. It has been found that in the presence of amine and phenolic type of agents during vulcanization with peroxides, the crosslink yield has been diminished considerably, and that the inhibitors are completely, or partially used up in this process. It is also noted that acetophenone and phenyl dimethylcarbinol, which are formed in crosslinking with DCP, interfere with the measurements of degradation by oxygen. Dependable measurements of degradation by oxygen in the presence of inhibitors can be carried out only on samples which have been extensively extracted with acetone in order to remove the acetophenone and phenyl dimethylcarbinol, and subsequently treated with a solution of the inhibitor, and carefully dried in nitrogen or in vacuum before measurement. if these conditions are fulfilled, the relaxation curves show an induction period, during which the stress drop is of zero order; the drop is directly proportional to the concentration of the inhibitor and the proportionality constant depends on the specific chemical constitution of the inhibitor. The rate of the stress drop is constant during the induction period and inversely proportional to the concentration of the inhibitor—which is in agreement with the theory of autoxidation.
Raman Spectra of Polyisoprene Rubbers
Authors: Cornell S. W. , Koenig J. L. 
Published: February 2011

Abstract
The Raman spectra of cis-1,4-, trans-1,4-, and 3,4-polyisoprene are presented, and the frequencies are classified by configurational structure type. The stretching frequency of the carbon-carbon double bond vibrations are used to describe structure content. Only Raman bands characteristic of total 1,4 content and total vinyl content can be observed. Tentative values of structure content determined by both peak height and peak area are presented for two mixed structure rubbers.
New Alfin Rubbers
Authors: Newberg R. G. , Greenberg H. , Sato T. 
Published: February 2011

Abstract
Molecular weight control for alfin catalyzed 1,3-diene polymers by 1,4-diene straight chain or cyclic hydrocarbons (and their derivatives) has been demonstrated. The microstructure of these moderated polymers is identical to the polymers obtained without molecular weight control. From the wide series of copolymers preparable with this improved polymerization method four were chosen for their evaluation after laboratory testing for processability, physicals, and economics. Copolymers of butadiene—isoprene (90/10 and 97/3) and butadiene—styrene (85/15 and 95/5) virgin or oil extended have been shown to be economically attractive and to give superior wear, traction, and adequate heat build up.
Radiotracer Studies of Carbon Black Surface Interactions with Organic Systems. II. Use of Sulfur-35 in Initial Studies on the Reactivity of “Bound” Surface Sulfur
Authors: Lewis J. E. , Deviney M. L. , McNabb C. F. 
Published: February 2011

Abstract
A broad investigation has been undertaken, using primarily radiochemical techniques, of the reactivity of the insoluble or “bound” sulfur on the surface of carbon blacks. The carbon black samples used in this study were prepared in small pilot plant reactors from sulfur-free commercial feedstocks to which had been added, in separate experiments, sulfur-35 tagged elemental sulfur, dibenzothiophene-S-35 and dibenzyl disulfide-S-35. After careful extraction-purification of the blacks, “chemical probe” studies were undertaken to gain knowledge of the nature of the surface sulfur complexes or functional groups, using reagents such as LiAlH4, trivalent phosphorus compounds, tetramethylthiuram disulfide, and hydrogen. These experiments demonstrated that bound surface sulfur possesses a considerable amount of chemical reactivity. Experiments were next designed to determine whether or not bound surface sulfur becomes involved in vulcanization reactions by, for example, exchange with added curing sulfur or accelerator. In radiotracer studies with SBR, natural rubber, and cis-polybutadiene vulcanizates, the results demonstrated that bound surface sulfur enters into the rubber phase during vulcanization. Finally, results from preliminary rubber physical testing and practical vulcanization studies involving pilot plant blacks (2% wt. sulfur) indicate that surface sulfur has little effect upon the vulcanization or final physical properties of SBR and NR.
Electron Micrography of Interplanar Spacings in Carbon Blacks
Authors: Marsh P. A. , Voet A. , Mullens T. J. , Price L. D. 
Published: February 2011

Abstract
High resolution electron micrography makes it possible to visualize the micro-structure of carbon black particles. An improved technique, relying on a graphitized carbon black as a calibration specimen, permitted us to establish an accurate distribution pattern of 002d-spacings in carbon blacks. Included were conventional blacks as well as a special thermal black (petroleum coke) untreated, partially and nearly completely graphitized. A technique was developed to microtome single particles. It was found that in untreated blacks, with a low degree of order, a wide, constant distribution of d-spacings exists, independent of the location within the particle. Upon heat treatment, the distribution pattern becomes increasingly narrower and shifts in the direction of smaller d-spacing values, as found in graphitized blacks. Oxidized blacks appear to have greater ordering of carbon planes, due to removal of unorganized fractions; but the d-spacing distribution remains essentially unchanged. Blacks subjected to high energy electrical discharges show a degree of order as in graphitized blacks. It was concluded that the distribution of d-spacings in a carbon black is a reflection of the particle's internal microstructural order.
A New Type of Crosslinking Agent for Elastomers
Authors: Breslow D. S. , Willis W. D. , Amberg L. O. 
Published: February 2011

Abstract
TBAF is a new type of crosslinking agent, which can be used to vulcanize a wide variety of elastomers, both saturated and unsaturated. The reaction involves the first-order decomposition of the azide function to give a nitrene, which in turn reacts with the polymer chain. The vulcanizates are noted for their lack of odor, lack of bloom, excellent physical properties, and excellent heat-aging resistance.
Preparation, Vulcanization, and Characterization of Syndiotactic Trans-1,2-Polypentadiene
Authors: Fielding-Russell G. S. , Smith G. H. 
Published: February 2011

Abstract
The polymerization, vulcanization, and some physical properties of two syndiotactic trans-1,2 polypentadienes (polypiperylenes) are described. Spectroscopic analysis indicated a significant (≈22%) cis-1,4 structure in the polymer prepared with the Et2AlCl/Co (AcAc)3 catalyst system which, although not in agreement with previously published data, is complementary to recently reported data. It is thought that the presence of water in the catalyst solvent or monomer mixture is responsible for the cis-1,4 content. Water appeared not to influence the Et2AlCl/Co(Octoate)2 polymerization in the same way: a greater than 95% trans-1,2 structure was obtained. Physical measurements on the vulcanizates reflected the structural differences. The copolymer vulcanizate, ≈22% cis-1,4 and ≈78% trans-1,2 structure, was more highly crosslinked than the polymer vulcanizate containing no detectable 1,4 structure. The relative levels and temperature location of the rubbery modulus and the Tg's and loss processes, respectively, are related to the 1,4 content: the vulcanizate containing 1,4 structure shows a higher Tg and rubbery modulus than the vulcanizate containing no detectable 1,4 structure. The inference is that the open copolymer presents a less sterically hindered path to the unsaturation for the bulky crosslinking agent and is therefore more susceptible to vulcanization, giving a tougher rubber that may also be reinforced by crystallization of the cis-1,4 units.
Rheo-Optical Studies of High Polymers. XIV. Study of the Deformation Mechanism in Polymer Blends of Polypropylene with Ethylene-Propylene Rubber
Authors: Onogi S. , Asada T. , Tanaka A. 
Published: February 2011

Abstract
To clarify the deformation mechanism in polyblends of polypropylene with ethylene-propylene rubber having different compositions, simultaneous measurements of the infrared dichroism with stress and strain under a constant rate of strain of 1.64%/min have been carried out. The orientation function of the crystallographic c axis of polypropylene in the blends has been obtained as a function of strain ranging from 0 to 20% and of polypropylene content ranging from 0.3 to 1.0. These results have been compared with the temperature dependences of the dynamic Young's modulus and of the loss modulus, as well as stress-strain curves for the same blends. The modulus data analyzed by Kerner's equation reveal the occurrence of phase inversion at polypropylene contents higher than about 0.5, and this is supported by the infrared dichroism data. The strong effect of quenching on crystalline structure and mechanical properties of pure polypropylene has also been elucidated.
A Topologically Interpenetrating Elastomeric Network
Authors: Frisch H. L. , Klempner D. , Frisch K. C. 
Published: February 2011

Abstract
While chemically different monomers can be mixed, the mixing of the corresponding polymers in the solid state usually results in (multiphase) polyblends. Even the mixing of two different polymer solutions generally produces two liquid phases. This difficulty can be overcome, without resorting to grafting, by producing interpenetrating polymer networks (IPN). By crosslinking an initially linear polymer in the presence of a crosslinked network we can produce a polymeric catenane or an IPN held together predominantly by “permanent” entanglements, assuming chain transfer reactions can be suppressed. Several workers have made IPN's from either chemically identical or chemically similar polymers and have studied their properties. In this work, two different elastomers, a crosslinked polyether-based poly(urethane-urea) and a linear poly(butadiene-acrylonitrile), as aqueous emulsions, are mixed, together with crosslinking agents and stabilizers, films cast, and subsequently cured to form the IPN. A partial chemical structure proof is obtained by separating the crosslinked poly(butadiene-acrylonitrile) from the IPN by essentially total hydrolysis of the interpenetrating poly(urethane-urea) network.