bluuebunny/crossref_metadata_2025_split huggingface dataset:
Self-Crosslinking Rubber/Rubber and Rubber/Thermoplastic Blends: A Review
Authors: Antony Prince , De S. K. , van Duin Martin 
Published: February 2011

Abstract
Blends of two or more polymers having appropriate reactive groups can be crosslinked through condensation or substitution reactions in the absence of crosslinking chemicals when molded at high temperatures for prolonged times. When at least one of the two polymers is a rubber, such blends are called “self-crosslinking rubber blends.” Self-crosslinking rubber/rubber blends included in this review are binary CSM/ENR, ENR/XNBR, CR/ENR, ENR/Zn-SEPDM, CSM/XNBR and CR/XNBR blends, and ternary CR/XNBR/ENR and CSM/XNBR/ENR blends. Self-crosslinking thermoplastic/rubber blends include binary PVC/XNBR, PVC/ENR, PVC/NBR, PVC/HNBR, PAA/CR and PAA/ENR blends, and a ternary PVC/ENR/XNBR blend. The formation of crosslinks in self-crosslinking blends is manifested in the rise of the rheometer torque with time. Solvent swelling studies and dynamic mechanical analysis support the self-crosslinking behavior of the blends. The extent of crosslinking depends on the amount and reactivity of the functional groups of the two blend components, the time and temperature of the reaction. In general, the self-crosslinked rubber/rubber blends behave like conventional rubber vulcanizates with respect to physical properties and can be reinforced by fillers. Infrared spectroscopy has been used to identify the chemical structures formed during self-crosslinking, allowing the elucidation of the mechanism of self-crosslinking.
Modulus Mapping of Rubbers Using Micro- and Nano-Indentation Techniques
Authors: Gillen Kenneth T. , Terrill Edward R. , Winter Robb M. 
Published: February 2011

Abstract
Modulus measurements are among the most useful properties available for monitoring the cure and aging of rubbers. Historically, such measurements were done on macroscopic samples, but over the past 15 years, several penetration techniques have been and are being developed that allow quantitative estimates of modulus to be made with lateral resolutions of 100 μm or better. This review summarizes these developments and the types of unique information that can be generated on rubbery materials. A large part of the review focuses on the types of results available from a modulus profiling apparatus that has been used to study rubbers for the past 15 years. This instrument allows estimates to be made of the inverse tensile compliance (closely related to Young's tensile modulus) with a lateral resolution of around 50 to 100 μm. Several recently developed alternative methods for achieving similar spatial resolution are also described. Finally, a brief review is given of the recent attempts to measure quantitative modulus values for rubbers with even better resolution using instruments historically focused on metals and other hard materials such as nano-indenters, the atomic force microscope and the interfacial force microscope.
Peroxide Vulcanization of Elastomers
Authors: Dluzneski Peter R. 
Published: February 2011

Abstract
This paper discusses the competing chemical reactions involved in the peroxide vulcanization of elastomers. Each of these reactions can have a profound effect on the cure characteristics as well as on the properties of the final vulcanizate. The balance between these reactions is determined by several factors including the type of polymer, type and concentration of peroxide, cure temperature, and the presence of other compound additives such as co-agents and antidegradants. The effects of all of these factors are discussed.
Application of Fracture Mechanics to Crack Growth in Rubber-Cord Laminates
Authors: Lake G. J. 
Published: February 2011

Abstract
The use of a fracture mechanics approach based on the strain energy release rate to assess failure due to the growth of fatigue cracks in rubber—cord laminated structures is discussed. The mechanics of crack propagation is considered for cracking either between the plies or around individual cords, and also for crack initiation and growth near cord ends. Energy release rates can be calculated approximately for each of these cases and enable the laminate results to be related to the independently measured crack growth characteristics of the rubber. Experimental energy release rate determinations, from compliance changes produced by propagating model inter-ply cracks by cutting, provide a check on the accuracy of the calculated energies. The approach identifies material properties relevant to laminate failure and indicates the effects of loading, design and construction parameters on the rate and nature of failure.
On the Mullins Effect in Silica-Filled Polydimethylsiloxane Networks
Authors: Clément F. , Bokobza L. , Monnerie L. 
Published: February 2011

Abstract
Silica-filled polydimethylsiloxane networks are submitted to successive stretching cycles, in order to get the stabilized stretching curve, at variable temperature. This study explains the peculiar temperature dependence of the first stretching curve of filled rubbers, and highlights the molecular origin of the stress-softening phenomenon, known as Mullins effect. Thanks to the comparison between the strain dependence of stress and the molecular orientation, this effect is attributed to the detachment from the filler surface or slippage on the filler surface, of chains having reached their limit of extensibility. Moreover, by taking advantage of Atomic Force Microscopy observations on stretched samples, the Mullins effect is shown to take place mainly in regions of high local concentration of silica. The experimental results are also compared to Bueche's model for the Mullins effect.
Ultrasonic Devulcanization of Unfilled SBR under Static and Continuous Conditions
Authors: Hong Chang Kook , Isayev A. I. 
Published: February 2011

Abstract
A static ultrasonic treatment device was used to investigate the effect of ultrasound on devulcanization of unfilled SBR disks in the absence of shearing effect. Some visible bubbles were observed at the center of the disk sample at low pressure, as well as at the edges at high pressure, as the treatment time increases. Evidently, these bubbles are a proof of the existence of cavitation during the ultrasonic devulcanization. Stronger reduction of crosslink density observed at a higher pressure in the treatment is a direct indication of the significant role of pressure in improving the efficiency of ultrasonic devulcanization. Treatment of the ground sample, having higher concentration of voids, indicated lower crosslink density and gel fraction than those of the sheet sample not having visible voids. The unique correlation between gel fraction and crosslink density of devulcanized rubbers observed earlier in continuous process, was also obtained in the present case. However, this curve is shifted towards higher values of crosslink density. It is concluded that shearing effect has an influence on improving the efficiency of devulcanization.
Finite Element Modeling of Indenter-Sample Contact During Force Imaging of Filled Rubber by Atomic Force Microscopy
Authors: Davis Mark K. , Eby R. K. 
Published: February 2011

Abstract
Finite element analysis (FEA) models were developed to study the interaction between atomic force microscope (AFM) tips and filled rubber compounds during nano-indentation. The filled systems were represented by simple models consisting of one or two discrete hard domains in a rubber matrix in order to study how such a hard domain at or near the location of an indentation measurement affected the force-distance response. Parameters studied included domain size and shape, lateral position and depth from the indentation location, effect of sample thickness, and the ability to measure modulus variation across “rubber-particle” interfaces. The analyses showed the degree to which the underlying and adjacent sample regions influenced the force-distance response at a given location. The results identified several limitations of force imaging as a characterization technique for filled systems and suggested a basis for the development of more complex FEA models.
Cracking Energy Density as a Predictor of Fatigue Life under Multiaxial Conditions
Authors: Mars W. V. 
Published: February 2011

Abstract
Rubber parts in service often experience complex strain histories that can cause mechanical failure. The ability to predict the effects of complex strain histories on fatigue life is therefore a critical need. This paper presents recent results of cyclic, combined tension/torsion fatigue experiments, and compares them with predictions based on a new parameter, the Cracking Energy Density. The Cracking Energy Density is the stored elastic energy density that is available to a crack on a given material plane, and can be calculated for an arbitrarily complex strain history. The ability of Cracking Energy Density to predict the fatigue life and cracking plane is evaluated for both in-phase and out-of-phase histories of combined axial and shear strain.
Elastomer Blends
Authors: Mangaraj Duryodhan 
Published: February 2011

Abstract
Blending of elastomers is often used to enhance he performance characteristics of rubber products. This article reviews the thermodynamic principles underlying polymer-polymer miscibility, with special reference to elastomer blends. It discusses the distribution of fillers, additives and curatives in different phases of the blend and its effect on the properties of the vulcanizate. It describes the different methods used in preparing elastomer blends, with special emphasis on compatibilization. Characterization of blends using optical and electron microscopy, solution properties, thermal and dynamic mechanical methods have been described along with results. The effect of blending on mechanical properties, hysteresis, adhesion and tack, transport properties and electrical conductivity has been discussed. Past attempts for property enhancement by blending elastomers have been reviewed, followed by a discussion of commercial application of elastomer blends.
Crosslinking of Rubbers by Fillers
Authors: Rajeev R. S. , De S. K. 
Published: February 2011

Abstract
Oxygen containing chemical groups on the carbon black surface can react with the carboxyl groups of XNBR, or epoxy groups of ENR, or chlorosulfonated groups of CSM, during high temperature molding of the rubber-filler mixtures. This leads to crosslinking of the rubber phase. The extent of crosslinking increases if the carbon black surface is oxidized, the concentration of the reactive groups of the rubber increases, or a suitable silane coupling agent is incorporated in the rubber-filler mixtures. Similarly, high temperature molding of the XNBR-precipitated silica, ENR-precipitated silica, CSM-precipitated silica, and CR-ferrite mixtures leads to crosslinking of the rubber phases, even in the absence of conventional rubber vulcanizing agents. XNBR-ZnO mixture on high temperature molding also produces crosslinked rubbers consisting of ionic crosslinks. During mixing stage, the reactive fillers interact with the polar rubbers leading to formation of high bound rubber, presumably through hydrogen bond formation. During high temperature molding of the rubber-filler mixtures for a prolonged time, the reactive groups on the filler surface chemically react with the functional groups of the rubber chains leading to crosslinks of the rubber phase. This is evident from the rise in the rheometric torque of the rubber-filler mixture and marked changes in properties of the mixture on high temperature molding. The properties in many instances are similar to that obtained in the case of rubbers crosslinked by conventional vulcanizing agents. Infrared spectroscopy has been used to identify the chemical structures at the filler-rubber interface formed during crosslinking of the rubber by the filler.
Compression of Bonded Rubber Blocks
Authors: Yeoh O. H. , Pinter G. A. , Banks H. T. 
Published: February 2011

Abstract
Many practical rubber component designs involve the compression of rubber blocks bonded to rigid metal plates. The rigorous analysis of such components is very difficult. However, a simple approximate method developed by Gent gives reasonably satisfactory predictions for stiffness and stress distribution provided deformations are kept small. Gent's “pressure” method is briefly reviewed for the classical cases of a long strip and a cylindrical disk. The method is then applied to more complex cases of a rectangular block and an annulus. The usual “incompressibility” assumption is relaxed to “near incompressibility” to yield more accurate solutions. Predictions have been verified using linear finite element analysis.
The Friction and Wear of Rubber Part 2: Micro-Mechanical Description of Intrinsic Wear
Authors: Gerrard David P. , Padovan Joe 
Published: February 2011

Abstract
The concept of a Damage Orientation Distribution Function was introduced in Part 1 of this series to describe the transient affect on wear generated by a dynamically changing slip orientation. In this Part an analytical model of the micro-mechanical processes that occur in a slipping rubber/abrasive interface is offered and serves as the basis for a new relation for the prediction of rubber wear.
The description considers the fatigue fracture processes that occur at the intrinsic nodule level. The assumption is made that each intrinsic nodule undergoes intermittent fractures which are driven by Strain Energy Release Rate levels that range from a minimum at or below the linear region of the material's Fatigue Crack Propagation curve, through the Power Law Region and finally to the catastrophic tear value.
The proposed description is tested against the early data of Schallamach. It is shown that the simple relationships offered in the analytical study can be used to predict rubber wear performance over a wide range of pressures and abrasive asperity sizes.
In light of this analysis, the Damage Orientation Distribution Function of Part 1 is revisited and found to be a useful tool when considering the fundamental processes that occur during unidirectional wear. Changes in slip direction are found to affect the instantaneous wear rate by affecting the Distribution Function in a different manner than changes in pressure or abrasive size. Changes in slip direction are shown to affect the population of intrinsic nodules immediately available for rupture while changes in pressure or abrasive size are shown to influence wear by changing the rate at which nodules move through the Distribution.
Why Do Cracks Turn Sideways?
Authors: Gent A. N. , Razzaghi-Kashani M. , Hamed G. R. 
Published: February 2011

Abstract
Calculations have been made by FEA of strain energy release rates G for a rubber sheet with a small edge crack, subjected to a far-field simple extension. Growth of the crack is considered in both forwards and sideways directions, the latter corresponding to crack splitting or turning. When the imposed extension is large, the value of G at which a small sideways crack will initiate is found to be a substantial fraction, about 60%, of that for further forwards growth. This suggests that crack splitting or turning will occur when the tear strength in the sideways direction is only slightly lower than that for forward growth. However, the value of G for a sideways crack decreases rapidly as the crack grows, indicating that it will stop after a short distance. These conclusions are shown to be in accord with experimental observations of crack splitting in filled rubber compounds and account for the phenomenon of reinforcement by fillers. In particular, they account for the fact that deep edge cracks are less likely to split or turn.
Effect of Third Monomer Type and Content on Peroxide Crosslinking Efficiency of EPDM
Authors: van Duin Martin , Dikland Herman G. 
Published: February 2011

Abstract
Peroxide crosslinking of EPDM is commonly applied in rubber practice. Although the presence of a diene termonomer is not a prerequisite for peroxide crosslinking, it does provide a significant increase of the peroxide crosslinking efficiency. Different explanations for the effect of the type and the amount of the third monomer on the peroxide curing efficiency have been put forward; but, a comprehensive overview and an acceptable explanation of all the effects observed are still lacking. In the present paper, this gap is filled by combining results from low-molecular-weight model studies and rheometer experiments with information from the literature. It is shown that peroxide crosslinking of EPDM proceeds via the combination of two EPDM macro-radicals and the addition of an EPDM macro-radical to the residual EPDM unsaturation. The extent to which the latter radical addition occurs, is governed by the amount of the third monomer and by the steric hindrance of the residual unsaturation of the EPDM, i.e. the lower the number of ipso- and β- alkyl substituents on the unsaturation, the higher the rate of addition. This explains why EPDMs containing termonomers with terminal unsaturations are more reactive than those with internal unsaturations. The same approach was followed to assess the peroxide curing efficiency of polydiene elastomers. It was found that the same steric effects govern peroxide crosslinking of polydiene elastomers, such as NR, IR and BR.
Dynamic Mechanical Properties of Precipitated Silica Filled Rubber: Influence of Morphology and Coupling Agent
Authors: Ladouce-Stelandre Laurence , Bomal Yves , Flandin Lionel , Labarre Dominique 
Published: February 2011

Abstract
Composites that incorporate precipitated silica into a vulcanized rubber were investigated for dynamic mechanical properties. Comparing different types of filler, it was found that the mean distance between particles did not alter Payne effect. On the contrary, the amount and morphology of the fillers played a major role on the macroscopic properties. The nature and amount of coupling or covering agents was also found to be an important parameter. A direct relationship between length and efficiency of interface agents was evidenced: longer silanes were more effective than shorter once independently from a covalent bounding to rubber. The set of studied parameters affecting Payne effect can be reduced to only two independents variables: the total amount of silica-rubber interface (a function of the amount of filler and its BET surface) and the quantity and nature of interface agent. From these data an attempt to relate the rubber to filler cohesion to Payne effect is proposed as well as a molecular mechanism derived from Maier and Göritz model. A mathematical treatment of the proposed mechanisms is currently being investigated that might help giving further insights on novel ways to further reduce Payne effect.
Adhesion Failure in Bonded Rubber Cylinders Part 1: Internal Penny-Shaped Cracks
Authors: Leicht D. C. , Yeoh O. H. , Gent A. N. , Padovan J. , Mullen R. L. 
Published: February 2011

Abstract
Rubber disks bonded between flat parallel metal plates are often used as adhesion test specimens such as ASTMD 429 1999, Method A. However, the mechanics of adhesion failure (debonding) for this geometry have not been fully analyzed previously. Therefore, a study has been conducted of the strain energy release rate (tearing energy) for bonded rubber disks having cracks at the rubber-to-metal bond. In this paper, we consider internal penny-shaped cracks. A future paper will discuss external ring cracks.
Finite element analysis was used to determine the tearing energy as a function of crack length for disks of various dimensions (shape factors). The crack configurations considered were an internal penny shaped crack located at the center of either one or both rubber-to-metal bonds. The rubber was assumed to be linearly elastic and nearly incompressible.
For any bonded disk held in constant tension, the tearing energy was found to be a non-linear function of crack length. For small cracks, the tearing energy was linearly related to the crack length. As the crack grew, the tearing energy increased until it passed through a maximum value. The peak tearing energy was found to depend on the height of the disk. Finally, for large cracks, the tearing energy decreased as the crack grew. Analytical and empirical models were developed and shown to be in good agreement for both small and large cracks in disks of different dimensions.
Novel Dynamically Vulcanized Elastomer-Polypropylene Blends with Improved Elasticity
Authors: Ellul M. D. 
Published: February 2011

Abstract
High elasticity in dynamically vulcanized EPDM-Polypropylene blends, as demonstrated by lower residual deformation upon release of constraint, is a much desired attribute. It has been found that this property can be improved beyond the conventional norms of highly crosslinking the rubber phase. This is achieved through the use of a polypropylene phase with a high degree of long-chain branching. The branching index, g', at molecular weight greater than 1×106 should be less than about 0.6. It is postulated that in the melt and at low frequencies the long-chain branched polypropylene behaves as a network. Therefore in the melt, the dynamically vulcanized alloy behaves as a dual network material: one network being the chemically crosslinked rubber phase, and the other being the physical network arising from the high level of long-chain branching in polypropylene. In the solid state, the co-continuous morphology arising from the choice of long-chain branched polypropylene contributes to the enhanced elasticity of the dynamically vulcanized thermoplastic elastomer.
Correlation of 13C NMR Analysis and Physical Testing Results of Natural Rubber
Authors: Parker Dallas D. , Koenig J. L. , Mori Makio 
Published: February 2011

Abstract
The methods of solid-state 13C NMR and physical testing were used to examine carbon black filled natural rubber samples. The rubber samples were vulcanized under varying parameters of sulfur loading, cure times, and cure temperature. At constant cure time and cure temperature, the two testing methods correlate well over a wide range of sulfur concentrations. Varying cure time and cure temperature produced large changes in the mechanical testing results but small change in the 13C NMR analysis of the sulfur vulcanizates.