bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemistry of Various Accelerators in an E-SBR Model Compound
Authors: Pierre C. C. , Datta S. , Datta R. N. , Talma A. G. 
Published: February 2011

Abstract
Sulfur vulcanization was carried out with 5-phenyl hex-2-ene serving as a model of e-SBR. Various accelerators have been used to study and compare the reactivity in a system containing sulfur and activators. Both HPLC and GC-MS analytical tools were used to identify the reaction products. It has been observed that the vulcanization in the presence of N-cyclohexyl-2-benzothiazole sulfenamide (CBS) generates a large amount of 2-marcaptobenzothiazole (MBT), which continuously increases and finally decreases suggesting further participation in vulcanization generating new crosslinks. The sulfenamide, N-cyclohexyl-4,6 dimethyl-2-pyrimidine sulfenamide (CDMPS) behaves different. Although it generates considerable amount of corresponding thiol, (4,6-dimethyl pyrimidine-2-thiol, DMMP) at the beginning of the reaction, no decrease has been observed during the course of further reaction suggesting that the accelerator, DMMP, somehow remains deactivated and therefore no changes in network is feasible. Identical differences exist between bis(2,2′benzothiazyl) disulfide (MBTS) and corresponding bis (4-methyl-2,2′benzothiazyl)disulfide (M-MBTS) in the reaction kinetics.
Influence of Nanosilica Particles on Hysteresis and Strain Induced Crystallization of Natural Rubber as Investigated by a Real Time True Stress-True Strain Birefringence System
Authors: Fiorentini F. , Cakmak M. , Mowdood S. K. 
Published: February 2011

Abstract
In this paper, the influence of nanosilica particles on hysteresis and stress induced crystallization of natural rubber compounds is described. For this purpose a newly developed uniaxial stretching system that monitors birefringence, true stress and true strain was used in real time while stretching and retraction is applied to the nanocomposite sheets. This allowed us to link the continuous structural measurements - as represented by birefringence - and the true mechanical properties during the actual stretching and retraction stages as influenced by the presence of nanosilica particles. The birefringence measurement system was also shown to be quite robust in detecting very low levels of retardation prevalent in rubbers. The stress optical behavior of unfilled NR compounds was compared with those filled with 5 phr and 10 phr nanosilica particles. This study allowed the determination of a critical birefringence value above which strain - induced crystallization occurs in the NR compounds. The results indicate that the addition of nanosilica reduces the stress optical constant of natural rubber compounds. In addition, the critical birefringence, above which the strain - induced crystallization occurs, decreases in the presence of 5 phr nanosilica thus indicating the enhancement of the crystallization process at this loading. However, the nanosilica loading beyond 5phr was not found to be a further benefit to strain - induced crystallization mostly because of the introduction of large surface area nanosilica agglomerates that act as a physical barrier between the chains that also most likely suppresses the crosslinking reaction during the preparation.
The Theory of the Rubber Elasticity of Ideal Networks With Entanglements; Application of the Theory to the Calculation of Stresses in Real Networks
Authors: Scherbakov Yu M. , Grishin B. S. 
Published: February 2011

Abstract
Based on the model of a freely hinged chain, the theoretical analysis of the configuration statistics of the ensemble of two freely hinged chains with entanglements is carried out. It is found that the laws of the chain ensemble deforming (at the micro level) and the deforming of the continuum element (at the macro level) can be described by similar relationships. The variation of constraints due to entanglements for the chain ensemble and the element surface area due to deformations λ1 and λ2 is similar. Based on that law, a method to describe constraints caused by entanglements for the chain ensemble is proposed. The theoretical derivation of an equation for the free energy of networks with entanglements in the absence of physical crosslinks is rendered, the obtained equation coincides with the empirical potential of Mooney-Rivlin in its form. The description of stresses in real networks with consideration for constraints due to entanglements and physical crosslinks is suggested. For the description of constraints due to physical crosslinks, the Flory-Erman theory of constrained junctions (CJ) is employed. A real network description is provided by modifying the CJ theory based on the results of the theoretical analysis of ideal networks with entanglements (the MCJ theory). The verification of the stress [f] dependence description was carried out proceeding from the reciprocal of the extension ratio λ−1 using the experimental data of H. Pak and P. J. Flory by simple extension-compression of polydimethylsiloxane (PDMS) networks with a different density of chemical crosslinks. The adequacy of the MCJ theory equation system for the calculation of the polymer stress-strain states is demonstrated.
Stiffness of Annular Bonded Rubber Flanged Bushes
Authors: Horton J. M. , Tupholme G. E. 
Published: February 2011

Abstract
Closed-form expressions are derived for the torsional stiffness, radial stiffness and tilting stiffness of annular rubber flanged bushes of finite length in three principal modes of deformation, based upon the classical theory of elasticity. Illustrative numerical results are deduced with realistic physical data of typical flanged bushes.
Numerical Simulation of Thermal Oxidation in Automotive Tires
Authors: Ellwood Kevin R. J. , Baldwin John , Bauer David R. 
Published: February 2011

Abstract
A finite element kinetic model has been developed to interpret issues related to accelerated aging of tires. The model is based on the Basic Autoxidation Scheme and incorporates mass transport limitations related to diffusion of oxygen into the layered elastomer system. The extent of oxidation is calculated at different locations within the tire as a function of time and temperature. Results for aging rates due to thermal oxidation predicted by the model are compared to experimentally derived data such as crosslink density, elongation-to-break and modulus variation. Comparative results for aging rates in different regions of the tire suggest that a reasonable accelerated oven testing temperature range is 60 °C to 70 °C. Additionally, initial results for predicted aging rates for a rolling tire are presenting indicating the thermal oxidation plays a large role in tire aging.
Recovery of Shear-Modified Polybutadiene Solutions
Authors: Roland C. M. , Robertson C. G. 
Published: February 2011

Abstract
We have investigated the recovery of the overshoot in the transient viscosity, the first normal stress coefficient, and the dynamic modulus for entangled polybutadiene solutions subjected to nonlinear shear flow. The molecular-weight dependences of the various time scales (linear viscoelastic relaxation time, entanglement recovery time, and timescale for decay of stress following cessation of shearing) are all consistent with the usual 3.4 power law. Nevertheless, the time for recovery of the stress overshoot and plateau value of the dynamic modulus were substantially longer (by as much as two orders of magnitude) than the linear viscoelastic relaxation time calculated from the Newtonian viscosity and the equilibrium recoverable compliance. These results indicate that complete entanglement recovery requires cooperative chain motions over a length scale exceeding that associated with linear relaxation. This persistence of a disentangled state means that a state of low viscosity and reduced elasticity is retained for an extended time, suggesting that shear modification can be used to facilitate the processing of polymers.
Viscoelastic Indentation and Resistance to Motion of Conveyor Belts Using a Generalized Maxwell Model of the Backing Material
Authors: Rudolphi Thomas J. , Reicks Allen V. 
Published: February 2011

Abstract
A one-dimensional Winkler foundation and a generalized viscoelastic Maxwell solid model of the belt backing material are used to determine the resistance to motion of a conveyor belt over idlers. The viscoelastic material model is a generalization of the three-parameter Maxwell model that has previously been used to predict the effective frictional coefficient of the rolling motion. Frequency, or loading rate, and temperature dependence of the material properties are incorporated with the time/temperature correspondence principle of linear viscoelastic materials. As a consequence of the Winkler foundation model, a normalized indentation resistance is independent of the primary belt system parameters - carrying weight per unit width, idler diameter and backing thickness - as is the case for a three-parameter viscoelastic model. Example results are provided for a typical rubber compound backing material and belt system parameters.
Some Geometric Considerations for Rubber—Metal Bond Test Specimens
Authors: Yeoh O. H. 
Published: February 2011

Abstract
Most methods for predicting fatigue lives of rubber components rely heavily on experimental studies that involve specimens subjected to essentially uniform states of deformation. But, in service, rubber components often fail at or near rubber-metal bonds where the state of deformation is far from uniform. Before experimental studies of fatigue failure in the vicinity of rubber-metal bonds, it is prudent to perform an analysis of the specimen geometry to make sure it has been optimized. This paper reports on finite element analyses of cylindrical rubber-metal bond test specimens recommended in ASTM D 429. The results suggest that taller specimens (height/radius ratio ≥ 2) have some advantages. Interpretation in terms of the strain energy release rate is recommended. A new asymmetric test specimen is proposed.
Structural Characterization of Terminal Groups in Natural Rubber: Origin of Nitrogenous Groups
Authors: Mekkriengkrai Dararat , Sakdapipanich Jitladda T. , Tanaka Yasuyuki 
Published: February 2011

Abstract
The nitrogenous groups in natural rubber (NR) from Hevea brasiliensis have been regarded as an important factor governing cured rubber properties, although there is no structural evidence. The nitrogenous compounds in highly purified NR were characterized to disclose the origin of nitrogenous groups. The rubber particles in fresh latex were purified by washing, i.e., successive dilution of the cream fraction and concentration by centrifugation in the presence of surfactant. The nitrogen content of natural rubber from the washed rubber particles decreased from 0.281% to 0.015% level after washing 3–5 times, the level of which was similar to that of deproteinized natural rubber with a proteolytic enzyme. The presence of 1–2 nitrogen atoms per rubber chain was presumed based on the nitrogen content and Mn value. The nitrogen content of fractionated rubber fractions from rubber particles washed 5 times increased with increasing molecular weight. The nitrogenous group in the rubber chain is postulated to originate from mostly phospholipids associating with branch-points and from functional groups formed by oxidation and successive reactions in latex.
A Two-Part Tale: The WLF Equation and Beyond Linear Viscoelasticity
Authors: Landel Robert F. 
Published: February 2011

Abstract
In this description of my work, I will first share some behind-the-scenes events in the discovery of the WLF. Then, I'll indicate why and how going to the Caltech/Jet Propulsion Laboratory led to our investigations of, and some results for, both large deformation uniaxial and biaxial responses in rubbers.
Synchrotron X-Ray Studies of Vulcanized Rubbers and Thermoplastic Elastomers
Authors: Toki Shigeyuki , Hsiao Benjamin S. , Kohjiya Shinzo , Tosaka Masatoshi , Tsou Andy H. , Datta Sudhin 
Published: February 2011

Abstract
Synchrotron X-ray diffraction technique has revealed strain-induced crystallization and molecular orientation in vulcanized rubbers and thermoplastic elastomers (TPE) during deformation in real time. The stress-strain curves and wide angle X-ray diffraction (WAXD) patterns in vulcanized rubbers and TPE were measured simultaneously. In-situ WAXD patterns were taken not only at different strains during uniaxial deformation but also at different temperatures at a constant strain. Results lead to several new insights. (i) Strain-induced crystallization is a common phenomenon in vulcanized rubbers, except SBR (styrene-butadiene rubber), and in TPE (with crystalline hard segments). (ii) Strain-induced crystallization decreases the stress and increases the elongation in the strained rubber. (iii) The hybrid structure of chemical networks and strain-induced crystallites is responsible to the tensile strength and elongation at break for both systems. (iiii) Some original crystal fraction (hard segment domain) in TPE is destroyed. During deformation, strain-induced crystallization increases with strain. Upon retraction even to stress zero, the majority of oriented strain-induced crystallites remains in tack with preferred orientation.
Review and the Latest Update of N-Nitrosamines in the Rubber Industry; the Regulated, the Potentially Regulated, and Compounding to Eliminate Nitrosamine Formation
Authors: Goss L. C. , Monthey S. , Issel H-M. 
Published: February 2011

Abstract
For several years, Germany has led the effort to eliminate the use of common nitrosamines in the rubber industry. Their TRGS 522(Nov 95) allows no more than 2.5 µg/m3 emission of nitrosamines between vulcanization and warehousing. Additionally, major U.S. Automobile manufacturers have issued stringent requirements with regards to the use of nitrosamines. One company has issued a restricted substances standard that prohibits the use of nitrosamines in excess of the 0.1 % threshold value of the part's total weight. With over 300 nitrosamines listed as either known or suspected carcinogens, safety continues to drive the elimination of nitrosamines in the rubber industry. Therefore, this is a review of nitrosamine regulations, identification of nitrosamines, how they are formed, and the latest in compounding essentials to produce non-nitrosamine generating compound.
Analysis of Fatigue Life under Complex Loading: Revisiting Cadwell, Merrill, Sloman, and Yost
Authors: Mars W. V. , Fatemi A. 
Published: February 2011

Abstract
An early study by Cadwell, Merrill, Sloman, and Yost reports fatigue lives under several combinations of static axial load and cyclic simple shear. The results have practical importance because similar loading situations commonly arise in many rubber components. This paper presents an analysis of these experiments. The objective of the analysis is to compare two approaches for rationalizing the reported fatigue lives. The first approach is based on a scalar parameterization of the loading history (strain energy density). The second approach is based on a parameterization of the loading history that is specific to particular material planes (cracking energy density). The analyses illustrate that a plane-specific approach provides a more successful framework for addressing several commonly encountered features of complex loading histories: multiaxiality of loading, non-relaxing loading cycles (R ratio effects), and crack closure during part of a loading cycle.
Carbon Black Distribution in the Components of Rubber Blends Monitored by Online Measured Electrical Conductance
Authors: Le H. H. , Qamer Z. , Ilisch S. , Radusch H-J. 
Published: February 2011

Abstract
The kinetics of carbon black (CB) dispersion in SBR/NR and EPDM/NR blends has been investigated using the electrical conductance measured online in the internal mixer. It is interesting to note that the infiltration and dispersion processes take place sequentially in the blend phases, which can be well characterized by analyzing the online conductance-time characteristics. A method for the estimation of the phase specific CB distribution in the blend was proposed by taking into consideration the online conductance values measured at the black incorporation time (BIT) of the blend components.
Small Indentations of Rubber Blocks: Effect of Size and Shape of Block and of Lateral Compression
Authors: Gent A. N. , Yeoh O. H. 
Published: February 2011

Abstract
Many gaskets and seals consist of a long rubber strip or thin-walled ring, placed on a flat rigid surface and indented by a flat-ended rigid indenter. We have examined their resistance to small indentations by FEA. They are treated as infinitely-long elastic blocks of rectangular cross-section, resting on a rigid frictionless base. The indentation stiffness is calculated for various ratios of indenter tip width to block width and to block thickness, using two restraint conditions on the outer surfaces: frictionless walls (zero outwards displacement), as for a gasket placed in a recess; or stress-free, as for a gasket with no lateral restraint. For an infinitely-wide and infinitely-thick block, the theoretical resistance to indentation is zero. For comparison, the indentation stiffness is calculated for cylindrical rubber blocks of varied radius and thickness, indented by a flat-ended cylindrical indenter. In this case the result for an infinitely-large block is finite. A second study treats indentation of a rubber block, pre-compressed in the surface plane. Biot showed that the indentation stiffness of a half-space becomes zero at a critical compression, about 33% for equi-biaxial compression and 44 % for plane strain compression, for both a neo-Hookean and a Mooney-Rivlin elastic solid. FEA calculations were made of the indentation stiffness of neo-Hookean blocks of various sizes, pre-compressed to various degrees. The results are compared with Biot's result. In an Appendix, the critical degree of compression is calculated for a more realistic strain energy function than either the neo-Hookean or the Mooney-Rivlin approximation.
Experimental Determination of Fatigue Crack Growth Behavior and Surface Strain Distribution of ‘Faint-Waist Pure Shear’ Specimens with Different Crack Tip Radii
Authors: Feichter Christian , Major Zoltan , Lang Reinhold W. 
Published: February 2011

Abstract
The influence of the initial crack-tip radius on the fatigue behavior and the strain distribution in the vicinity of the blunted crack tip was determined experimentally using a servo-hydraulic testing machine and an optical full-field strain analysis method. Two different elastomer grades (SBR, EPDM) were selected for the experimental work. The strain analysis method used, based on the image correlation technique, was found to be an effective tool to determine strains, strain distributions and gradients near the crack tip for elastomeric materials. Different material behavior was observed in the two rubber types investigated. While the crack tip was regularly blunted (half circle shape) for EPDM and the strain gradient was low (less steep), the crack tip was sharp (less blunted) with a higher strain gradient for SBR. Furthermore the crack tip radius was found to be an important influencing factor on the initiation of crack growth, but not on the crack growth behavior after initiation. Based on the experimental results a phenomenological, first-order, crack-growth initiation law was proposed, dependent on the crack tip radius, the tearing energy at crack growth initiation for a sharp crack and a parameter representing the influence of the crack tip radius.
Thermal Characterization of the Interaction of Silanes with a Dihydroxy Vulcanized Fluoroelastomer
Authors: Sands Michael Benjamin , Subramanian Vijay , Mao Guangzhao 
Published: February 2011

Abstract
The reactivity of aminosilane and vinylsilane with a dihydroxy (Bisphenol AF) crosslinkable fluoroelastomer containing only vinylidene fluoride (VF2) and hexafluoropropylene (HFP) was monitored using Differential Scanning Calorimetry (DSC) and X-ray Photoelectron Spectroscopy (XPS). The DSC results showed that the introduction of an aminosilane, or a combination of aminosilane and vinylsilane solutions, to the cure system of the fluoroelastomer resulted in a peak shift. This shift indicates that crosslinking in fluoroelastomer-silane system occurs at a lower temperature when aminosilane is present. Results also confirm that the organofunctional group on the silane reacts with the elastomer. XPS analysis of the silane-coated fluoroelastomer heated at 120 °C, 160 °C and 200 °C reveals that dehydrofluorination of the polymer is one of the steps in the reaction. It is our hypothesis that the amine group on the aminosilane is a contributor to the dehydrofluorination of the fluoroelastomer.
Comparison of Hyperelastic Models for Rubber-Like Materials
Authors: Marckmann G. , Verron E. 
Published: February 2011

Abstract
The present paper proposes a thorough comparison of twenty hyperelastic models for rubber-like materials. The ability of these models to reproduce different types of loading conditions is analyzed thanks to two classical sets of experimental data. Both material parameters and the stretch range of validity of each model are determined by an efficient fitting procedure. Then, a ranking of these twenty models is established, highlighting new efficient constitutive equations that could advantageously replace well-known models, which are widely used by engineers for finite element simulation of rubber parts.
The Correlation of Fatigue Crack Growth Rates in Rubber Subjected to Multiaxial Loading Using Continuum Mechanical Parameters
Authors: Mars W. V. , Fatemi A. 
Published: February 2011

Abstract
Although both the crack nucleation and growth stages of the fatigue failure process in rubber are manifestations of the same characteristic material behavior, the nucleation stage deserves special attention. In this case, continuum mechanical parameters may be used to characterize the driving forces of small cracks, without reference to the geometry of the test piece. The ability to estimate crack driving forces from continuum mechanical parameters during the growth process of small cracks has been investigated by correlating three different parameters (maximum principal strain, strain energy density, and cracking energy density) to rates of crack growth observed photographically during fatigue tests on initially uncracked specimens. Significant scatter in crack growth rates was observed resulting from high crack density and crack interactions. These results are also compared to crack growth measurements made on a pure shear (planar tension) test piece. The difference between continuum parameters that refer to a specific material plane, and those that do not is emphasized. Generally, the maximum principal strain and cracking energy density parameters provided similar levels of correlation. The strain energy density parameter consistently gave the poorest correlation. An advantage of the cracking energy density is that it considers the experiences of specific planes embedded in the material (i.e. it is a plane-specific parameter).
Recycled Rubber: The Rubber Granulate - Virgin Rubber Interface
Authors: Kumar P. , Fukahori Y. , Thomas A. G. , Busfield J. J. C. 
Published: February 2011

Abstract
Reusing granulates derived from old tire stock and other sources in high tech engineering applications is still considered a high risk option. In addition to ensuring that the granulates are correctly identified, it is important to know how the incorporation of these materials alters the intrinsic flaw size of a finished product and to see how much the strength of the interface between these materials and the virgin materials compares to the basic strength of the virgin stock and the granulates. This paper explores possible techniques that can examine both properties so that an informed evaluation of the effect of reincorporating granulates can be established in practice.