bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polysulfide Sealants
Authors: Ghatge N. D. , Vernekar S. P. , Lonikar S. V. 
Published: February 2011

Abstract
Sealants based on polysulfide liquid polymers are widely used in a number of applications. These sealants are solvent and chemical resistant, having good flexibility and adherence to many substrates such as steel, aluminum, glass, concrete, wood, etc. These are used to line fuel tanks of aircraft and to seal fuel tanks and rivetted joints in aircraft. These sealants, being water resistant, are widely used in ship building to seal decks and planking. Since these sealants have good weather resistance and can withstand stress and strain, they are widely used in the building industry. They are found to be very satisfactory in modern curtain walls and in sealing windshields of motorcars. Their use in airfield and runway constructions is well known. These sealants generally have a two-pot system consisting of (i) a base caulk containing a liquid polysulfide polymer, fillers, plasticizers, adhesive promotors, thickening agents, accelerators or retarders and (ii) a curing agent. Sometimes accelerators and retarders are used as a third pot system to regulate the pot life of caulking compounds.
Rubber Adhesion of Brass-Plated Steel Tire Cords: Fundamental Study of the Effects of Compound Formulation Variations on Adhesive Properties
Authors: van Ooij W. J. , Weening W. E. , Murray P. F. 
Published: February 2011

Abstract
The rubber adhesion of brass-plated steel tire cord has been studied with emphasis on the effects on unaged and aged adhesion of compound formulation variations. A series of 16 test compounds was formulated in which the levels of sulfur, accelerator, stearic acid, zinc oxide and cobalt salt were varied. Adhesion data for two steel cord constructions—4 × 0.25 and 7 × 4 × 0.175 + 0.15—obtained under various unaged and aged conditions are presented. Despite the relatively minor compound differences, a wide variation of adhesion characteristics was observed. Good adhesion following overcure, humidity aging and steam aging was obtained with compounds containing high sulfur levels and high sulfur to accelerator ratios. The adhesion data do not correlate with compound crosslink densities or other physical properties. Rates of brass sulfidization do not correlate with adhesion data either. This was studied in model systems with squalene replacing the natural rubber. Analysis by high-resolution Auger electron spectroscopy revealed differences between the compositions of the sulfide films formed by the good and the poor mixtures of the series. The locus of the adhesion failure of the poor compounds was found to be the interface between copper sulfide and zinc oxide, the two reaction products formed when brass is bonded to rubber. A model was presented which accounted for the effects of compound formulation variations. It is postulated that brass is not sulfidized by the free sulfur in the mixture but by an intermediate containing reactive sulfur. The composition of this intermediate is dependent on the compound formulation. This leads to different types of sulfide films formed by good or poor compounds. This model is based on the chemistry of squalene model system mixtures, which was studied by chromatography. The ranking of crosslink densities observed for the various squalene mixtures was very similar to that determined for the corresponding NR mixtures. Some implications of the findings of this study for tire cord and compounding practice were discussed.
An Approach to the Modeling of Mixing of Elastomers
Authors: Nakajima N. 
Published: February 2011

Abstract
In recent years, the process of mixing elastomers with carbon black has been the subject of various studies. In particular, the process involving the use of the internal mixer has been examined systematically, and Palmgren has published a general review on the state of the art. A method was proposed for the control and scale-up which is based on the energy input for mixing; then, properties were evaluated as a function of the mixing energy. This method was used for evaluating the performance of different types of elastomers and carbon blacks in the internal mixer. Although the method represents significant progress in understanding the mixing process and is of practical importance, it still treats the mixer essentially as a “black box”. In order to elucidate the mechanism of mixing, visualization must be performed. One type is static visualization, in which the machine is stopped at an intermediate stage and the contents are taken out for inspection. Another is dynamic visualization through transparent walls of a mixer. These observations enable us to construct a model for the deformation-flow behavior of materials and a model for the mixing mechanism. These models, in turn, guide us to laboratory measurements of the material behavior which are pertinent to the mixing mechanisms. With respect to mill processability, Tokita and White classified raw material behavior into four regions, which are functions of a given material and dependent on the time scale, temperature, and magnitude of strain. This classification is applicable not only to the millability of the raw elastomer but also to the ease of mixing with carbon black. This interpretation may be extended to the processability of the material in the internal mixer.
A Low Modulus, High Fatigue Life Elastomer Compound for Suspension Applications
Authors: Killgoar Paul C. , Lemieux Marvin A. , Tabar Ronald J. 
Published: February 2011

Abstract
Soft elastomeric suspension bushing compounds have been developed which are based on natural rubber/polybutadiene (NR/BR) blends which have been softened with polyisobutylene (IM). The new compounds have a Shore A hardness of 45 and a fatigue life of 97 kc and 80 kc for the urethane cured and semi-EV cured compounds respectively. This compares with a fatigue life of 62 kc for the current production compound (Shore A 65). It appears that the mechanical behavior, i.e. resistance to crack growth, of natural rubber based compounds is unaffected by the addition of IM. Fatigue life, compression set and retention of physical properties after heat aging of the new compounds are also superior to the production compound. The dynamic mechanical properties of the new compounds were evaluated and found to have a slightly greater temperature sensitivity than the production compounds.
Amine Terminated Reactive Liquid Polymers; Modification of Thermoset Resins
Authors: Riew C. K. 
Published: February 2011

Abstract
Amine terminated reactive liquid polymers (AT-RLP) are synthesized from corresponding carboxyl terminated reactive liquid polymers (CT-RLP) and diamines. The CT-RLPs have a functionality of close to two, the average molecular weight ranging from 2500 to 4000, and Brookfield viscosity ranging from 30 to 600 Pa · s at 27°C. AT-RLPs made from the CT-RLPs have about the same physical properties as the CT-RLPs given above. N-(2-aminoethyl)piperazine (AEP2) is the best diamine among the diamines tried to produce low viscosity and low molecular weight AT-RLPs. Structure of end-groups of AT-RLP is unequivocally identified as a secondary amide and a secondary amine group resulting from the reaction of carboxyl end-groups of CT-RLP and a primary amine group of AEP,. The AT-RLP can be used as a modifier for epoxy resins at room or elevated temperatures to produce castable formulations with properties ranging from plastics to elastomers. The formulations may be useful as a modifier for improvement of crack and/or impact resistance of normally brittle epoxy plastics, as castable elastomers, paints and coatings, sealants, adhesives, especially as solventless adhesives for conveyor belts, hoses, shoes, and as binders for woven or non-woven fibers and cords.
Structural Mechanics of Radial Tires
Authors: Akasaka T. 
Published: February 2011

Abstract
This review has included only theoretical studies of cross-sectional tire shape, structural properties of the belt, and certain topics on structural mechanics of radial tires. Many other papers on these subjects have been omitted because of the space limitation and because of the objective to describe only broad trends and prospects rather than to present an exhaustive review. Many different but interesting problems remain regarding stresses, deformations, and failure of radial tires under various loading conditions, for example: ( 1 ) physico-chemical and mechanical studies of the viscous flow and vulcanization of rubber during tire formation, in order to determine the setting mechanism and residual stresses in the cord-rubber array; (2) theoretical studies of both in-plane and interply loads and deformations in laminates of more than three layers, by developing a three dimensional lamination theory; (3) accurate determinations of spring bed coefficients in equations based on a shell model (e.g. for use in a ring model, which could yield a closed form solution for various tire performance parameters); (4) experimental and analytical studies of elastic properties and strengths of twisted tire cords under various conditions of extension, compression, bending, and torsion; (5) experimental and analytical studies of the distribution of contact pressure between a radial carcass and a belt (which pressure strongly affects the cross-sectional shape of a tire, especially near the belt edges); and (6) theoretical studies of the cross-sectional shape of the inflated radial tire by relating the bending rigidity of the body, particularly near the bead, to the mold shape.
Determination of Sequence Distribution in Styrene-Butadiene Copolymer I. 1H-NMR Study of Styrene Oligomers
Authors: Tanaka Y. , Sato H. , Saito K. , Miyashita K. 
Published: February 2011

Abstract
The 1 H-NMR spectra of styrene oligomers were measured as a model of styrene sequences in SBR. The ortho-phenyl proton, methine proton, and methylene proton signals shift to a higher magnetic field as the degree of polymerization increased. The methine proton signal split into two peaks, reflecting the tacticity. The methylene proton flanked by methylene and methine protons had a higher chemical shift value than the methylene proton flanked by two methine protons. It is demonstrated that the average sequence length of the styrene units in SBR can be determined by the relative intensity ratio of the two methylene proton signals. It is also found that the fraction of styrene sequences longer than 6 units can be estimated from the relative intensity of ortho-phenyl proton signals resonated higher than 6.7 ppm.
Characterization of the Reversion Process in Accelerated Sulfur Curing of Natural Rubber
Authors: Chen C. H. , Koenig J. L. , Shelton J. R. , Collins E. A. 
Published: February 2011

Abstract
From studies of a series of accelerated sulfur vulcanizations of natural rubber, the structural basis of the reversion in macroscopic physical-mechanical properties has been determined. The amount of chemically induced trans-methine butadiene-like structure increases as the reversion process proceeds. When there is no observable reversion, there is no detectable trans-methine butadiene-like structure. The presence of the trans-methine butadiene-like structure is detrimental to the properties of the natural rubber vulcanizate. The vulcanization process involves two competing processes, namely, crosslinking and desulfuration. The latter process produces the trans-methine structure which is responsible for the reversion in properties.
Radial Truck Tire Inflation Analysis: Theory and Experiment
Authors: Kennedy R. H. , Patel H. P. , McMinn M. S. 
Published: February 2011

Abstract
The finite element method is a useful tool in the design process to give deformations, strains and stresses in tires when they are loaded. To show this, a geometrically nonlinear, materially homogeneous, and generally orthotropic finite element model is described and used in the inflation analysis of radial truck tires. The element, a linear strain axisymmetric triangle, has three displacement degrees of freedom at each node in order to correctly model the three-dimensional states of strain and stress present in generally orthotropic structures. Two radial truck tires, a tube-type 10.00R20 and a tubeless 11R22.5, are analyzed both experimentally and analytically for inflation loading. Experimentally, cord forces are measured by cord force transducers, belt edge interply shear strain is measured by a pin rotation technique, sidewall growth is measured by a laser profilometer, and sidewall strains are measured with liquid metal strain gages. These values are compared with those predicted by the finite element model. The model works well for the tube-type 10.00R20 tire and above the mid-sidewall of the tubeless 11R22.5 tire. Further work needs to be done on the lower sidewall and bead area portions of the 11R22.5 tire model. The finite element model and solution procedure for the 11R22.5 radial truck tire is used for trend predictions. Several tire construction features, belt bias angle, belt end count, body ply end count, and bell skim stock modulus are varied, and their effect on inflation growth, strains and cord forces are predicted. The largest effect on inflation behavior was variation of the belt bias angle. The other features had minor effects. These predicted trends are important in giving the design engineer direction in creating new tire types or modifying current designs.
A Curing System for Rubber Bonded to Brass-Plated Tire Cord
Authors: Barker L. R. , Bristow G. M. 
Published: February 2011

Abstract
Devising a suitable vulcanizing system for steel cord carcass mixes presents unusual problems. A relatively high proportion of sulfur needs to be present to react with the brass plating, but this is not generally regarded as good compounding practice, particularly from the point of view of heat-aging resistance. If an attempt is made to improve matters by increasing the ratio of sulfenamide accelerator to sulfur, adhesion suffers. To help resolve these problems, it is suggested that the accelerator N-oxydiethylenebenzothiazole-2-sulfenamide is used in conjunction with dimorpholinyl disulfide. Good adhesion can be obtained with no more than 3.5 parts phr of sulfur and only a moderate amount of vulcanization activator, such as zinc stearate, is needed for maximum state of vulcanization. Insufficient work has been carried out to reach a position where a complete formulation can be recommended, but it is believed that the following vulcanizing system could be used as the basis for achieving a high standard of adhesive bond between a natural rubber tire carcass mix and brass-plated steel tire cord: (see PDF for table)
Softer Conductive Rubber Compounds by Elastomer Blending
Authors: Sircar A. K. 
Published: February 2011

Abstract
Carbon black parameters that impart high conductivity in elastomer compounds, i.e., high surface area, structure, and porosity also increase compound viscosity and thus cause processing problems. In the present study, an attempt has been made to circumvent the problem by modification of the elastomer phase. Many black loaded elastomer pairs show maxima in their electrical conductivity-composition curves; the maxima are several orders of magnitude higher than that exhibited by the component elastomers. Moreover, the curves of viscosity and hardness vs. elastomer composition show either flatter maxima or even minima in some cases. Thus, conductivity with respect to the single elastomers can be increased without corresponding increases in viscosity or hardness values. The above phenomenon can be explained by elastic modulus and electron microscope investigations of black loaded elastomer blends. Elastic modulus data of black loaded blends show increased agglomeration of the carbon network in the case of incompatible elastomer pairs. Electron microscopic examination of these compounds reveals a redistribution of the carbon black. Redistribution occurs from the less reactive or less viscous polymer to the blend interface, even when black is added to the former. Accumulation of black at the interface reduces the gap width by increasing the number of contact points to result in an overall conductivity increase. The conditions for maximum conductivity were determined from the conductivity-composition curves of several elastomer pairs. It was concluded that the redistribution of carbon black, which causes the conductivity increase, can take place if the elastomers in a pair are highly incompatible and differ widely in their black interaction (e.g., NBR-CIIR), or in their viscosity (e.g., NR-CR).
Tear Strength and Tensile Strength of Model Filled Elastomers
Authors: Dreyfuss P. , Gent A. N. , Williams J. R. 
Published: February 2011

Abstract
Measurements have been made of the tear strength, tensile strength, and energy dissipated during stretching for model filled elastomers consisting of polybutadiene with glass beads incorporated. The glass beads were pretreated with various silanes, some of which could, in principle, form covalent bonds with the polybutadiene matrix during free-radical crosslinking of the latter and some of which could not. The tear strength of the elastomer was increased by the addition of glass beads, by about 25% for the largest beads, having a mean diameter of 150 µm. This effect is attributed to increased roughness of the tear path. The breaking elongation in tension was reduced by the addition of glass beads but the breaking stress was only seriously reduced for the least-well-adhering beads. The stored strain energy density at break was reduced in all cases. This is attributed to large glass beads acting as fracture nuclei in tension. Calculated sizes of a Griffith crack, 150–300 µm, are consistent with this hypothesis. Strain energy dissipated due to dewetting was found to be in the range 4–13% of the input energy, depending upon the degree of interfacial adhesion, in addition to about 10% dissipated in the unfilled material. The maximum value observed is in reasonable agreement with theoretical predictions.
Current Perspectives on Silicone Rubber Technology
Authors: Polmanteer K. E. 
Published: February 2011

Abstract
This perspective embraced many factors that are important in understanding silicone elastomer technology and the reasons for the unique properties that they exhibit. The fact that they possess the lowest transition temperatures for any known polymer qualify them as a viscoelastic polymer that can be converted to an elastomer by crosslinking. Important also is the fact that the polymer molecules are predominantly linear prior to vulcanization, which allows high extensibility when the chemical crosslinks are in the desirable range of 100–400 mer units. Siloxane chemistry is uniquely different from hydrocarbon chemistry primarily because silicon is more electropositive than carbon, and the siloxane bonds possess more ionic character. Intermolecular forces for polydimethylsiloxane based elastomers are much lower than hydrocarbon polymer based elastomers. These polymers exhibit unusually high chain flexibility, easy rotation of pendant organic groups attached to silicon, and more free volume at ambient conditions than other polymers. These properties contribute to the lower Tg values and less change in properties (e.g., viscosity of polymers, elastomer modulus and strength) with temperature, compared with organic elastomers. Additional properties that contribute to the unique properties of silicone elastomers are low surface energy, excellent oxidative and thermal resistance formulatibility to provide excellent resistance to hydrolysis and rearrangement of siloxane bonds, easy modification of solubility characteristics by substitution of different organic groups on silicon, and the use of simple chemistry alterations that allow a range of molecular weights for making high and low consistency compositions that can be crosslinked either at elevated or room temperature conditions by a variety of reactions. The unusually high degree of reinforcement obtained with silica fillers compared with nonreinforced silicone polymers is a result of excellent polymer filler bonding which consists of largely physical bonds with some chemical bonds also being present after exposure to elevated temperature curing conditions. The combination of the above mentioned properties contribute to the fact that silicone elastomers have become important engineering materials that find hundreds of difficult-to-satisfy applications. Based on the excellent potential for continued technology advancement for silicone elastomers, it is believed that substantial future growth of this family of elastomers will occur.
Adhesion and Friction of Elastomers
Authors: Roberts A. D. 
Published: February 2011

Abstract
Use of mirror smooth spheres and cylinders of rubber allows the thickness and contour of a liquid film trapped between surfaces to be studied by optical interferometry. Close normal approach reveals the load bearing capacity of electrical double layer forces. In the absence of such forces, a liquid film collapses leading to areas of adhesion over most of the contact region. The adhesion can be interpreted in terms of surface energy. The force required to separate adhered surfaces is found to depend critically upon the rate of separation. Dry contact observations reveal that under nonequilibrium conditions the apparent surface energy may be very much greater than the equilibrium energy. The observations can be used, in certain circumstances, to predict tack, rolling resistance and sliding friction. Such prediction reflects a combination of surface properties and bulk viscoelasticity of the rubber. In particular, the approach has been applied to rolling on rough surfaces and to the friction of rubber on ice.
Morphology of Heat Set Segmented Elastomers
Authors: Van Bogart J. W. C. , Gibson P. E. , Cooper S. L. 
Published: February 2011

Abstract
The technique of small-angle x-ray scattering (SAXS) was used to investigate the morphology of three heat set (200–400% strain at 110–125°C) segmented elastomer samples—two polyester-polyurethanes and one polyether-polyester. The degree of hard-segment ordering in the samples varied from amorphous to slightly crystalline to highly crystalline. The results showed that the hard-segment domains in the semicrystalline materials developed axial ratios of about 2:1 for the axes parallel and perpendicular to the direction of stretch, while the sample with amorphous hard-segment domains showed no similar distortion in hard-segment domain shape and no anisotropy in the thickness of the interface between hard- and soft-segment domains.
Copolymerized Antioxidants in Polyether-Ester Elastomers
Authors: Wolfe J. R. 
Published: February 2011

Abstract
Antioxidants copolymerized into polyether-ester elastomers increase the resistance of the elastomers to degradation by heat aging. Resistance to heat aging increases as antioxidant content increases, with no bloom formation at high antioxidant content. The addition of a small amount of a nonbound amine antioxidant further increases the resistance to heat aging of elastomer protected by copolymerized phenolic antioxidant. The 3,5-di-t-butyl-4-hydroxybenzenepropanamido structure is a more effective antioxidant in these polyether-ester elastomers than the 3,5-di-t-butyl-4-hydroxybenzamido structure.