bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fatigue and Fracture of Elastomers
Authors: Lake G. J. 
Published: February 2011

Abstract
The use of an energetics approach to treat various aspects of fatigue and fracture in elastomers is reviewed. Topics covered include tearing, crack growth and fatigue, tensile failure, oxidative effects, environmental cracking, cutting by sharp objects, abrasion, adhesion, friction (under circumstances where it is determined mainly by the making and breaking of contact), and cavitation. Application of the approach to service problems is also considered. Finally, physical and chemical factors affecting the crack growth characteristics—the material property linking various types of cohesive failure—are discussed.
Nitrile Rubber—Past, Present and Future
Authors: Hertz D. L. , Bussem Hermann , Ray T. W. 
Published: February 2011

Abstract
Nitrile rubber (NBR) has been the work-horse elastomer in oil and gas production for the past fifty years. Random seal and packer failures have been encountered in the more agressive fields. The higher temperatures and increasing percentages of hydrogen sulfide (H2S), naturally occuring or through well stimulation directly or indirectly, initiate the failure mechanism(s). Future applications of nitrile rubber in higher temperature production should only be considered after reviewing the range of potential chemical attacks that are possible by of the aqueous environment (well fluids, completion fluids and stimulation fluids). This paper briefly outlines the scope of chemical attacks that can and will be encountered.
Sulfur Vulcanization of Simple Model Olefins, Part IV: Vulcanizations of 2,3-Dimethyl-2-Butene with TMTD and Activated Zinc Dithiocarbamate/Xanthate Accelerators at Different Temperatures
Authors: Versloot P. , Haasnoot J. G. , Reedijk J. , van Duin M. , Put J. 
Published: February 2011

Abstract
The mechanism of the accelerated sulfur vulcanization of rubber was studied by the use of 2,3-dimethyl-2-butene (C6H12, TME) as a simple, low-molecular model alkene. Treatment of TME with a mixture of ZnO, S8 and the classical accelerator TMTD at temperatures above 100°C yields a mixture of addition products ((C6H11—Sn—C6H11) ). In the temperature range of 50 up to 100 °C only intermediate products, C6H11—Sn—S(S)CN(CH3)2 are obtained. Room temperature vulcanization is feasible using highly reactive accelerators, such as xanthate derivatives. These derivatives result in formation of the crosslink precursors which are converted to the actual crosslink in the presence of zinc dithiocarbamates. The addition of (secondary) amines enhances the solubility of the dithiocarbamates, and therefore the reactivity of the xanthate/zinc dithiocarbamate combination.
Crosslink Densities and Phase Morpholgies in Dynamically Vulcanized TPEs
Authors: Ellul Maria D. , Patel Jaymini , Tinker Andrew J. 
Published: February 2011

Abstract
Recent developments in characterization techniques have permitted estimation of the crosslink density attained in dynamically vulcanized thermoplastic elastomers. The range of techniques available for investigation of the phase morphology of this type of TPE has also increased. The characterization of experimental TPEs based on natural rubber/polypropylene and EPDM/polypropylene is reported here. A combination of several optical and electron microscopy techniques were employed. Crosslink densities estimated by swollen-state NMR spectroscopy are presented and are corroborated by estimates from a network visualization technique for TPEs.
Rubber Cylinders under Hydrostatic Pressure with Variable Poisson's Ratio
Authors: Holownia B. P. 
Published: February 2011

Abstract
Elastomers are increasingly used in specialized engineering applications where their complex shape often requires a detailed stress analysis. Specialized programmes have to be used for incompressible materials such as elastomers, since the standard computer finite element packages are unable to give accurate solutions for rubbers with Poisson's ratio close to 0.5. The present paper uses an established finite difference method to examine the deflected shape of rubbers under hydrostatic pressure. A particular case of a rubber cylinder subjected to hydrostatic pressure is examined, where a natural tendency is to assume that the rubber cylinder will reduce slightly in volume, evenly all the way round. However, by performing a detailed finite difference analysis, it was found that the final shape, under pressure, was dependent on the value of Poisson's ratio, and height to diameter ratio of the rubber cylinder. An interesting result is that the end of the cylinder, and the circumferential surface will change shape from a concave to a convex surface by changing the value of ν for certain cylindrical shapes of rubber.
Evaluation of the External Surface Area of Carbon Black by Nitrogen Adsorption
Authors: Magee R. W. 
Published: February 2011

Abstract
Specific surface area is an important property for carbon black grade classification, production control, and prediction of rubber reinforcement characteristics. Total surface area alone is insufficient for estimating the reinforcing properties of a microporous carbon black because the internal area of the micropores is inaccessible to rubber molecules. The CTAB surface area test, based on adsorption of a molecule too large to enter the micropore, measures the surface area available to rubber. Although widely used, the CTAB method has failed to gain wide popularity due to its labor-intensive nature and poor testing precision. In the present paper, the extent of microporosity on the surface of carbon blacks is investigated. The external surface area derived from the nitrogen adsorption characteristics is compared to CTAB surface area for a number of standard rubber carbon blacks. This study reports the optimum testing conditions to achieve precise external surface area measurements and the ability of this method to overcome the disadvantages of the CTAB method. Other advantages of this technique are discussed.
A Triboelastic Model for the Cyclic Mechanical Behavior of Filled Vulcanizates
Authors: Coveney V. A. , Johnson D. E. , Turner D. M. 
Published: February 2011

Abstract
Aspects of the mechanical behavior of filled vulcanizates are reviewed with reference to existing mathematical models. The basic equations of the triboelastic theory, previously described by Turner, are derived. A standard triboelastic solid (STS) three parameter model, analogous to the standard linear solid, is described and a computationally efficient approximation developed. Comparisons are made between the predictions of the STS model and the behavior of testpieces of heavily filled natural rubber vulcanizates when subjected to simple and to complex deformation histories at various frequencies; the model is found to give a satisfactory representation of material behavior. Limitations of the STS model are also discussed.
Solubility of Sulfur and Dithiocarbamates in Natural Rubber
Authors: Morris M. D. , Thomas A. G. 
Published: February 2011

Abstract
Knowledge of equilibrium solubilities of sulfur and accelerators in rubbers at various temperatures allows prediction of whether blooming is possible in particular compounds or products. Reliable data of this nature for natural rubber appeared not to exist in the literature. Immersion of 1 mm thick sheets of peroxide-vulcanized natural rubber in both liquid and, more surprisingly, powdered solid curatives was found to be an adequate method for measuring solubilities. The same experimental method also enabled some diffusion data to be obtained. Solubilities of sulfur, zinc diethyldithiocarbamate (ZDEC) and zinc di-n-butyl dithiocarbamate (ZDBC) were determined at various temperatures between 23° and 135°C. The experimental results did not agree well with the theory which had previously been found to describe the solubility of waxes in natural rubber. This theory, which is a combination of the Flory-Huggins Equation with an expression for the latent heat of fusion, was modified to take into account the dependence of the interaction parameter on temperature and on degree of swelling. The new expression gave much better agreement with the experimental results for all three substances.
Effect of Bromination on the Properties of Ethylene-Propylene-Diene Rubber in the Presence of Divinylbenzene
Authors: Yoon J. R. , Ikeda Y. , Hashim A. S. , Kohjiya S. 
Published: February 2011

Abstract
The curing behavior and vulcanizate properties of EPDM and brominated EPDM (BEPDM) were compared using a dicumyl peroxide curing system. The BEPDM displayed lower torque and crosslink density, but better tensile properties than the EPDM. In the presence of divinylbenzene (DVB) coagent, all vulcanizates, i.e., EPDM, BEPDM, and their blends with natural rubber, had improved tensile properties. At low DVB concentration, the filler effect of DVB on the modulus enhancement was noticed. At high and comparable DVB concentration, both the BEPDM and NR/BEPDM blend showed significantly higher modulus (M100) and tensile strength than their EPDM counterparts. The BEPDM was also found to have higher crosslink density and storage modulus (E′) than the EPDM. This observation could be attributed to the better dispersion of DVB in the BEPDM and NR/BEPDM vulcanizates, as supported by TEM measurements. The TEM data is also consistent with the properties observed on the uncured mixes, in which the NK/BEPDM + DVB mix has favorable viscosity and die swell properties due to the more homogeneous DVB dispersion in the rubber phases. Thus, the bromination of EPDM has resulted in better processing and vulcanizate properties of the rubber and its blend with natural rubber.
Encapsulation in Ternary Elastomer Blends
Authors: Koseki Yasuaki , Lee Moo Sung , Macosko C. W. 
Published: February 2011

Abstract
Ternary elastomer blends of acrylonitrile-butadiene rubber (NBR), chlorinated polyethylene (CM), and ethylene-propylene rubber (EP) have been investigated using transmission electron microscopy (TEM). Especially the effect of comonomer content, chlorine in CM and acrylonitrile in NBR, on blend morphology is studied. The blend ratio of NBR/CM/EP is fixed at 10/20/70 by weight: EP acts as matrix and NBR and CM comprise dispersed phases. TEM observation is possible without staining due to a natural contrast between NBR and CM. From TEM micrographs it is clear that NBR/CM/EP blends show encapsulated structures. Which component will be the encapsulating layer depends on comonomer contents. For blends containing high acrylonitrile content (NBR46), CM forms the encapsulating layer; whereas, for blends with low acrylonitrile (NBR16), NBR16 encapsulates CM. The encapsulation behavior of NBR/CM/EP blends is interpreted in terms of a spreading coefficient concept combined with solubility parameter and melt viscosity differences between NBR and CM. Our calculation based on simple thermodynamic considerations explains the morphology observed in this study except for the NBR16/CM29/EP blend.
Thermal Properties and Crystallization Behavior of Highly Deproteinized Natural Rubber
Authors: Kawahara Seiichi , Kakubo Takashi , Suzuki Michio , Tanaka Yasuyuki 
Published: February 2011

Abstract
Natural rubber was deproteinized with a proteolytic enzyme and surfactant to reduce nitrogen content less than 0.02%. The deproteinized rubber was further purified by acetone-extraction followed by transesterification with sodium methoxide. The density of rubber decreased and the thermal expansion coefficient increased by deproteinization and transesterification. The glass transition temperature, Tg, was slightly reduced after deproteinization and transesterification. These were explained in relation to the decrease in gel content of the rubber. The equilibrium melting temperature, Tm0, was practically unchanged by these treatments. The low-temperature crystallization between −30 and −10 °C was significantly influenced by free fatty acids present as a mixture and fatty acid groups linked to the rubber chain. The crystallization behavior was independent of Tg and Tm0 values.
Deformation of Laminated Elastomer Composites
Authors: Luo Shen-Yi , Taban Faruk 
Published: February 2011

Abstract
Flexible elastomer composites subjected to finite deformation are usually associated with significant fiber re-orientation and configuration change which cannot be described by classical composite lamination theory. Utilizing the Lagrangian description and a strain-energy density approach, this work presents a set of 2-D constitutive equations in terms of the overall deformation of laminated composites. This model includes both geometric and material nonlinearities of the laminate. Interlaminar shear deformation is addressed but not studied in this analysis. Theoretical predictions have been compared with the available experimental data about symmetric laminates with various fiber orientations in the finite deformation range. Also, a parametric study has been performed under various ratios of biaxial deformation.
2-t-Butylbenzothiazole Sulfenamide Accelerated Sulfur Vulcanization of Polyisoprene
Authors: Gradwell M. H. S. , van der Merwe M. J. 
Published: February 2011

Abstract
The mechanism of 2-t-butylbenzothiazole sulfenamide (TBBS) accelerated sulfur vulcanization of polyisoprene was investigated. Samples of compounded rubber were heated in a differential scanning calorimeter to preselected temperatures or degrees of vulcanization, the reaction stopped, and the products analyzed. TBBS polysulfides, formed from the reaction of TBBS with sulfur, react with the rubber chain to form benzothiazole pendent groups and free t-butylamine. The delayed action of TBBS accelerated sulfur vulcanization was shown to be due to an exchange reaction involving benzothiazole terminated pendent groups and TBBS. Crosslinking occurred very rapidly once the TBBS was depleted. Special reference was made to the role of the amine. Reaction mechanisms were proposed to account for the formation of products.
The Mechanical Behavior of a Slightly Compressible Rubber-Like Material: Correlation of Simulations and Experiments
Authors: Moreau C. , Thuillier S. , Rio G. , Grolleau V. 
Published: February 2011

Abstract
The purpose of this paper is to present a different approach for modeling the mechanical behavior of a compressible rubber-like material. In this approach, the motion of the body is described in the current configuration in convected material frames and the Cauchy stress tensor and Almansi strain tensor are used. The hyperelastic constitutive law, corresponding to this approach, is also presented. Non-homogeneous experiments on compact chloroprene specimens were carried out, in order to show the possibilities of the model. The material parameters are identified using an inverse problem approach, based on the minimization of the gap between the experimental load-displacement curve and the simulated one and on a numerical calculation of the cost function gradient. Results show that over a set of three different non-homogeneous and multiaxial tests, there is a good correlation between experiments and simulation.
Characterization of Hevea Brasiliensis Rubber from Virgin Trees: A Possible Role of Cis-Polyisoprene in Unexploited Tree
Authors: Sakdapipanich Jitladda , Tanaka Yasuyuki , Jacob Jean Louis , d'Auzac Jean 
Published: February 2011

Abstract
The role of rubber in Hevea brasiliensis was analyzed based on the structural analysis of rubber in rubber trees as latex. The rubber obtained from a mature-tree which has never tapped before, so-called “virgin mature-tree” (Vir-NR), contained the gel fraction higher than 80%, while that from a regularly tapped mature-tree (Reg-NR) was less than 3%. The gel showed almost the same structure as a crosslinked rubber prepared from fresh latex in the presence of peroxide, with the molecular weight between crosslinks (Mc) of 3×103. This value is extremely low comparing with that of 7×105 observed for the soft-gel in rubber from high-ammonia latex and Pale crepe. The sol fraction from Vir-NR was an oxidative degraded product containing aldehyde and epoxide groups. Aging properties of Vir-NR are much worse than those of Reg-NR. This indicates that rubber accepts free-radicals to form C-C crosslinking and partly oxidative scission of main-chains during storage in laticiferous tubes of Hevea trees. This suggests that a possible role of rubber is a scavenger of free-radicals in latex, due to lack of the naturally occurring antioxidants. The consecutive tappings of latex from the first opening mature-tree resulted in the formation of rubber similar to that obtained from Reg-NR, after six days. This modification indicates that the new regulation mechanisms in latex biosynthesis, which is induced by exploitation, can avoid the rubber chain crosslinkings and increase their elongations.
Effect of Water Soluble Polymers on Radiation Vulcanized Natural Rubber Latex Films
Authors: Varghese Siby , Katsumura Yosuke , Makuuchi Keizo , Yoshi Fumio 
Published: February 2011

Abstract
Technological properties of radiation vulcanized latex after mixing with water soluble polymers (WSP) such as poly(vinyl alcohol), poly(ethylene oxide) etc. have been studied in detail. The properties of water soluble polymer incorporated vulcanizates depend mainly on the type of the polymer blended into the latex. Most of the polymers showed a drastic increase in tear strength with polymer content and a reduction in tackiness of the vulcanized films. Radiation processing increases the water soluble protein content in the serum phase whereas that in the rubber phase decreases. Addition of water soluble polymer causes the fast leaching of soluble proteins from the dried films, which reduces the prolonged leaching commonly adopted for rubber vulcanizates. Aging properties of radiation vulcanized films incorporated with water soluble polymers are excellent. The thermal degradation behavior of radiation vulcanized films and that of water soluble polymer incorporated films is almost the same. Transparency of the rubber films can be increased by the addition of suitable water soluble polymers.
Studies of Peroxide Curing of cis-1,4-Polyisoprene/Diallyl Phthalate Blends by Spectroscopic Techniques
Authors: Oh Sung Joon , Koenig Jack L. 
Published: February 2011

Abstract
Peroxide curing of cis-1,4-polyisoprene/diallyl phthalate blends was studied by the analytical techniques of equilibrium swelling, differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR), and solid-state nuclear magnetic resonance (NMR). Although the overall curing kinetics are controlled by the peroxide decomposition rate, the addition of a coagent into the rubber matrix catalyzes the curing reactions. The increase in peroxide and coagent concentrations in the blend results in a decrease in T2 relaxation times, which is caused by restricted segmental mobility due to the increase in crosslink density. It is suggested that phase separated coagent domains are chemically bound with the rubber matrix, providing the decrease in segmental mobility.
Effect of Surface Oxidation of Carbon Black on Its Bonding with Epoxidized Natural Rubber in the Presence of Silane Coupling Agent
Authors: Manna Ajay K. , De P. P. , Tripathy D. K. , De S. K. , Chatterjee M. K. 
Published: February 2011

Abstract
Results of bound rubber determination, Monsanto rheometry, solvent swelling studies and measurement of physical properties reveal that high temperature molding of epoxidized natural rubber (ENR) filled with intermediate super abrasion furnace (ISAF) carbon black and surface oxidized ISAF carbon black, in the presence of silane coupling agent, namely, N-(4-vinylbenzyl)-N′-[3-(trimethoxysilyl)propyl]ethane-1,2-diamine monoHCl salt, results in crosslinking of the rubber phase, even in the absence of the vulcanizing agents. Infrared spectroscopic studies show formation of silyl ether, in the case of ISAF carbon black, whereas the oxidized grade forms both silyl ether as well as silyl ester and amide linkage. Oxidation of ISAF carbon black causes an increase in the extent of coupling bond formation.
An Extended Tube-Model for Rubber Elasticity: Statistical-Mechanical Theory and Finite Element Implementation
Authors: Kaliske M. , Heinrich G. 
Published: February 2011

Abstract
A novel model of rubber elasticity—the extended tube-model—is introduced. The model considers the topological constraints as well as the limited chain extensibility of network chains in filled rubbers. It is supplied by a formulation suitable for an implementation into a finite element code. Homogeneous states of deformation are evaluated analytically to yield expressions required e.g., for parameter identification algorithms. Finally, large scale finite element computations compare the extended tube-model with experimental investigations and with the phenomenological strain energy function of the Yeoh-model. The extended tube-model can be considered as an interesting approach introducing physical considerations on the molecular scale into the formulation of the strain energy function which is on the other hand the starting point for the numerical realization on the structural level. Thus, the gap between physics and numerics is bridged. Nevertheless, this study reveals the importance of a proper parameter identification and adapted experiments.
Mechanisms Involved in the Recycling of NR and EPDM
Authors: Verbruggen M. A. L. , van der Does L. , Noordermeer J. W. M. , van Duin M. , Manuel H. J. 
Published: February 2011

Abstract
The thermochemical recycling of natural rubber (NR) and ethylene-propylene-diene rubber (EPDM) vulcanizates with disulfides was studied. NR sulfur vulcanizates were completely plasticized when heated with diphenyldisulfide at 200 °C. It could be concluded that both main chain scission and crosslink scission caused the network breakdown. NR peroxide vulcanizates were less reactive towards disulfide at 200 °C, and only reacted through main chain scission. For EPDM a temperature range of 200–275 °C was studied. In the presence of diphenyldisulfide at 200 °C there was almost no devulcanization of EPDM sulfur vulcanizates, and at 225 and 250 °C there was only slightly more devulcanization. A decrease in crosslink density of 90% was found when 2×10−4 mol diphenyldisulfide/cm3 vulcanizate was added and the EPDM sulfur vulcanizates were heated to 275 °C. EPDM peroxide vulcanizates showed a decrease in crosslink density of ca. 40% under the same conditions. The lower reactivity of EPDM towards disulfide compared with NR is the result of higher crosslink densities, the presence of a higher percentage of more stable monosulfidic crosslinks and the fact that EPDM is less apt to main chain scission relative to NR.
Ozone Detection by Crack-Induced Opacity in Rubber
Authors: Mott P. H. , Roland C. M. 
Published: February 2011

Abstract
Initially transparent polybutadiene develops micron-sized surface cracks when stretched and exposed to ozone. The consequent reduction in the transparency of the rubber provides a facile method for quantifying the ambient ozone concentration. The rate at which opacity develops is linearly dependent on the amount of ozone, and increases with increasing strain. This method of detecting atmospheric ozone has high sensitivity (1 ppb), a broad dynamic range, and is unaffected by the presence of other chemicals. The surface morphology of exposed material can be interpreted in terms of crack nucleation and growth.