Showing papers in "Rubber Chemistry and Technology in 2002"
TL;DR: In this paper, the authors consider the strain energy on a phenomenological basis by Alan Gent to take into account limiting chain extensibility in rubber-like materials and show that this mode is not optimal.
Abstract: We consider the strain energy recently proposed, on a phenomenological basis by Alan Gent to take into account limiting chain extensibility in rubber-like materials. We show that this mode...
154 citations
TL;DR: In this article, the state-of-the-art silane modification of precipitated silica for rubber applications is described, where bifunctional silanes are used to provide a silica-to-rubber coupling.
Abstract: The silane modification of precipitated silica for rubber applications is state-of-the-art. Usually, bifunctional silanes are used to provide a silica-to-rubber coupling. In this paper, th...
135 citations
TL;DR: In this article, the Cracking Energy Density (CED) is used to predict the fatigue life and cracking plane for both in-phase and out-of-phase histories of combined axial and shear strain.
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.
107 citations
TL;DR: The addition of a coupling agent to silica-rubber compounds enhances the filler-matrix compatibility as discussed by the authors, and the surface of the filler may be only partly activated under certain mixing conditions.
Abstract: The addition of a coupling agent to silica-rubber compounds enhances the filler-matrix compatibility. Under certain mixing conditions the surface of the filler may be only partly activated...
100 citations
TL;DR: A review of the many reports related to the silica/silane filler system, as well as alternative approaches to lower rolling resistance, that have been generated since the introduction of the green tire concept in the early 1990s can be found in this paper.
Abstract: Strong demands for lower rolling resistance tires in Europe led to the introduction of a new filler system for auto tire treads in the early 1990s. Silica, in combination with a silane coupling agent, was used as the primary filler system despite the increased costs compared to carbon black. The adoption of silica/silane treads has been slower outside of Europe, but some conversion to silica/silane or alternative filler blends has taken place in North America and Japan. This paper is a review of the many reports related to the silica/silane filler system, as well as alternative approaches — including new carbon blacks — to lower rolling resistance, that have been generated since the introduction of the “green tire” concept in the early 1990s.
85 citations
TL;DR: In this paper, the reduction of filler flocculation and the degree of polymer-filler interactions were found to depend on the type and the concentration of silane added, and the mixing drop temperature (Td) used.
Abstract: Filler flocculation was followed for silica filled compounds containing various alkoxy silanes and non-silane type polar additives. The methodology employed in this paper permitted a quantitative characterization of filler flocculation and polymer-filler interactions after heating the compound under conditions that simulated vulcanization. With the addition of trialkoxy silanes, the reduction of filler flocculation and the degree of polymer-filler interactions were found to depend on the type and the concentration of silane added, and on the mixing drop temperature (Td) used. Greater polymer-filler interactions and flocculation suppression were obtained with a compound containing a tetrasulfane when compared to that containing either a disulfane or a monofunctional-silane. Polar additives such as an amine compound and a sugar alcohol did not reduce the silica flocculation during simulated vulcanization because they were dewetted from the silica surface upon heating. The filler flocculation proces...
71 citations
TL;DR: In this paper, the change in Mooney viscosity (ML1+4) with aging was followed for silica filled compounds containing various silanes and polar additives, and several mechanisms for the aging stability were postulated and evaluated through experimentation.
Abstract: The change in Mooney viscosity (ML1+4) with aging was followed for silica filled compounds containing various silanes and polar additives. Several mechanisms for the aging stability are postulated and evaluated through experimentation. The type of silane or polar additive used can cause the ML1+4 to increase or even decrease during aging. When bis(triethoxy silanes) are used in silica filled rubbers, the ML1+4 growth during aging is caused by hydrolysis. Silica-silica bridging was found to be responsible for the ML1+4 growth in rubber compounds containing a more thermally stable polysulfide or a sulfur-free bis(triethoxy silane). When the bis(triethoxy silane) is bis(3-triethoxysilylpropyl) tetrasulfide (TESPT), a fraction of TESPT is attached to the unsaturated rubber to give polymer-silica attachments. These attachments further enhance the hydrolytic ML1+4 increase during aging. Chemical coating of the silica with a monofunctional silane or a physical coating with a trialkyl amine compound effe...
45 citations
TL;DR: In this paper, a brief look into the mechanism of sintering is presented along with information about the influence of molding variables, such as time, temperature, pressure and rubber particle size on the mechanical properties of the produced parts.
Abstract: High-pressure high-temperature sintering (HPHTS) is a novel recycling technique that makes it possible to recycle vulcanized rubber powders made from waste rubber (namely scrap tires) through only the application of heat and pressure. A brief look into the mechanism of sintering will be presented along with information about the influence of molding variables, such as time, temperature, pressure and rubber particle size on the mechanical properties of the produced parts. One of the most interesting observations is that powders of every crosslinked elastomer attempted sintered together via this technique, including silicone rubber (SI), sulfur cured [natural rubber (NR), ethylene-propylene-diene rubber (EPDM), styrene-butadiene rubber (SBR)], peroxide cured butadiene rubber (BR), and fluoroelastomers (FKM). Early work on sintered rubber made from commercially available rubber powder had a modulus of 1 to 2 MPa, strength of 4 to 7 MPa and an elongation at break of 150–250%. Recently, in-house groun...
44 citations
TL;DR: In this paper, a new carbon-silica dual phase filler (CSDPF) 4000 has been developed for passenger tire application, which features higher levels of silica at the surface of aggregate and higher silanol contents compared with the CSDPF 2000 family of products introduced previously.
Abstract: A new carbon-silica dual phase filler (CSDPF) 4000 has been developed for passenger tire application. Analytically, this filler is featured by higher levels of silica at the surface of the aggregate and higher silanol contents compared with the CSDPF 2000 family of products introduced previously. From the compounding point of view, this new dual phase filler shows higher polymer-filler interaction on the carbon domains and lower filler-filler interaction relative to the conventional fillers used in tire tread compounds. The new filler shows significant improvement in wet skid resistance over the earlier products. When this filler is employed in passenger tire tread compounds, the tradeoff among rolling resistance, wear resistance and wet skid resistance of the tire can be significantly improved compared with conventional fillers.
43 citations
TL;DR: In this article, the authors studied the rate and extent of crystallization in crosslinked samples of natural rubber (NR), cis-1,4-polybutadiene (BR), and butyl rubber (IIR), held at low temperatures.
Abstract: The rate and extent of crystallization in crosslinked samples of natural rubber (NR), cis-1,4-polybutadiene (BR), and butyl rubber (IIR), were studied by observing the relaxation of stress in stretched strips, held at low temperatures. Melting temperatures were measured from the recovery of stress on warming. The melting temperature was raised by stretching, and the rise was significantly greater for NR than for BR, consistent with the lower heat of fusion of NR. In some cases crystallization was also followed by volume changes, or by DSC or x-ray diffraction. The maximum degree of crystallization was estimated to be only about 20% for BR, 28% for NR, and somewhat higher for IIR. On raising the temperature the tensile strength showed a marked drop to only 1–2 MPa when the elastomer failed to crystallize on stretching. At lower temperatures, when strain-induced crystallization occurred, the tensile strength was much higher, but the values were different for the three elastomers: about 10 MPa for B...
39 citations
TL;DR: In this article, the chemical branching that formed at both chain ends of the rubber molecule during the preservation of the latex in the presence of ammonia was attributed to the outstanding properties of natural rubber, e.g., green strength and rapid crystallization.
Abstract: The outstanding properties of natural rubber, e.g., green strength and rapid crystallization, were attributed to the chemical branching that formed at both chain ends of the rubber molecule during the preservation of the latex in the presence of ammonia. The gel content of natural rubbers from various clonal origins increased during the preservation, but decreased after deproteinization of the aged latex. The crystallization of acetone-extracted rubber was slightly suppressed as the gel content increased. The increase in green strength during the preservation was studied in connection with the gel content and degree of branching of the rubber.
TL;DR: In this article, the carboxyl groups of XNBR, or epoxy groups of ENR, or chlorosulfonated groups of CSM, during high temperature molding of the rubber-filler mixtures.
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 bo...
TL;DR: In this article, the same minimum stress of zero (s min = 0) and varying stress amplitude (S a ) predictably gave decreased fatigue life with increased stress amplitude and hence maximum stress (s max ), however, tensile uniaxial cyclic tests where s min was increased in successive tests while alternating stress remained constant, produced longer fatigue lives for higher values of s max.
Abstract: Fatigue tests on ethylene propylene (EPDM) and styrene-butadiene (SBR) rubber reveal physical behavior that is not seen in conventional linear elastic solids. Uniaxial cyclical tests, using cylindrical dumbbell specimens, with the same minimum stress of zero (s min = 0) and varying stress amplitude (S a ) predictably gave decreased fatigue life with increased stress amplitude and hence maximum stress (s max ). However, tensile uniaxial cyclic tests where s min was increased in successive tests while alternating stress (s a ) remained constant, produced longer fatigue lives for higher values of s max . EPDM and SBR compounds were chosen for the tests because they do not strain crystallize during deformation. Cossequently, this phenomenon has no influence. The results show that s max can not be used as criterion to predict fatigue life of elastomers. Preliminary evaluation of recorded data of stress vs. strain gave evidence that energies control the fatigue life rather than stress and strain. Experimental results on filled and unfilled rubber materials are evaluated and discussed as well as the consequences on predictions of component properties.
TL;DR: In this paper, Gent's "pressure" method is briefly reviewed for the classical cases of a long strip and a cylindrical disk and then applied to more complex cases such as a rectangular block and an annulus.
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.
TL;DR: In this paper, a variety of natural rubber vulcanizates of various crosslink densities were tested in uniaxial tension and their relative strength depended on cut size, which was associated with an unusual increase in strength with increasing cut size.
Abstract: Conventional sulfur-cured, gum natural rubber vulcanizates of various crosslink densities were prepared Dumbbell test pieces with and without edge precuts were tested in uniaxial tension. Relative strengths of the different vulcanizates depended on cut size. Lightly crosslinked specimens exhibited an abrupt drop in strength at a critical cut size. c e f , which became smaller as crosslink density increased because of reduced strain crystallizability At all cut depths, crack growth was simply perpendicular to the loading direction and crack surfaces were smooth. A moderately crosslinked composition exhibited crack deviation prior to rupture. This was associated with an unusual increase in strength with increasing cut size. Densely crosslinked networks exhibited lateral fracture, like the lightly crosslinked gums, but produced a jagged crack contour path reflective of a rough fracture surface. Moreover, for the highly crosslinked samples, a critical cut size was not found. Rather, log-log plots of strength versus cut depth were linear and had slopes slightly greater than minus one-half.
TL;DR: In this paper, the tensile strength of gum and N115-filled natural rubber test pieces, with and without edge pre-cuts, was determined, at low crosslink density.
Abstract: Tensile strengths, σb, of gum and N115-filled natural rubber test pieces, with and without edge pre-cuts, have been determined. At low crosslink density, the regular (uncut) σb of filled a...
TL;DR: The TRC-IR showed an endothermic transition peak at around 185 °C on the differential scanning calorimetry (DSC) chart, indicating cleavage of the hydrogen bonding.
Abstract: Thermoreversible crosslinking rubber (TRC-IR) was easily synthesized by modification of isoprene rubber (IR) with maleic anhydride followed by the addition of 3-amino-1,2,4-triazole (ATA), in solid phase. The mechanical properties of the resulting rubber were more similar to the sulfur-vulcanized rubber than general thermoplastic elastomers (ex. SEBS). Although the tensile strength and elongation at break were lower than those of a corresponding sulfur-vulcanized rubber, the moduli were as high as those of sulfur-cured rubber. Re-molding of TRC-IR could he repeated more than 10 times without significantly changing its mechanical properties. Differential scanning calorimetry (DSC) and infrared analyses revealed that the superior mechanical properties and good recyclability are attributable to the strong hydrogen bonding. The TRC-IR showed an endothermic transition peak at around 185 °C on the DSC chart, indicating cleavage of the hydrogen bonding. Infrared analyses also revealed that the absorption peaks of carboxylic acid were shifted to a lower region by the strong hydrogen bonding. The thermoreversible crosslinking system was also applied to EPM, EBM (ethylene-butene rubber), and IIR. These rubbers also showed superior mechanical properties as well as excellent recyclability.
TL;DR: In this paper, the effect of surface treatment on silica agglomerate dispersibility was investigated by using a commercially available coupling agent Bis-(triethoxysilylpropyl)-tetrasulphane (TESPT) in a blender.
Abstract: The effect of surface treatment on silica agglomerate dispersibility was investigated. Precipitated silica powders were treated with a commercially available coupling agent Bis-(triethoxysilylpropyl)-tetrasulphane (TESPT) in a blender. Spherical agglomerates of known density were prepared and dispersed in styrene butadiene rubber (SBR) under controlled flow conditions. The erosion kinetics was monitored by measuring the reduction in size of parent agglomerate with time. Silica dispersibility was greatly enhanced upon surface treatment. The coupling agent used in surface treatment is known to reduce filler—filler interactions and therefore affects the intrinsic cohesivity of the powder. However powder surface treatment can also induce changes in agglomerate morphology and filler-liquid interactions. The work presented in this paper evidences such changes.
TL;DR: In this article, a static ultrasonic treatment device was used to investigate the effect of ultrasound on devulcanization of SBR disks in the absence of shearing effect, and some visible bubbles were detected.
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 ...
TL;DR: A wide range of polymers have been used for wire and cable insulation as mentioned in this paper, including natural, butyl, and styrene-butadiene rubber, and new materials include crosslinked polyethylene...
Abstract: A wide range of polymers has been used for wire and cable insulation. Older materials include natural, butyl, and styrene-butadiene rubber. Newer materials include crosslinked polyethylene...
TL;DR: The rubber properties vary considerably as a function of clone type, tapping method and season of the year, whereas both nitrogen % and ash % increase in the same period.
Abstract: The latex and natural rubber from rubber trees [Hevea brasiliensis (Willd. exAdr. de Juss.) Muell. Arg.] from clones (RRIM 600, IAN 873, GT 1 and PB 252) recommended to the state of Sao Paulo, Brazil, were studied in three different tapping systems. The parameters studied were dry rubber content (DRC), percentages of ash and of nitrogen, Wallace Plasticity (P0) and Mooney Viscosity (VR). The rubber properties vary considerably as a function of clone type, tapping method and season of the year. DRC tends to decrease in the beginning of the dry, cold season (May and June), whereas both nitrogen % and ash % increase in the same period. A good linear correlation was obtained for P0 and VR. The highest P0 and VR were obtained for RRIM 600.
TL;DR: In this paper, the increment of crack growth during each cycle is shown to result from the sum of time dependent and cyclic crack growth components, which is characterized by the relation between the tearing energy.
Abstract: Engineering components are observed to fail more rapidly under cyclic loading than under static loading. This reflects features of the underlying crack growth behavior. This behavior is characterized by the relation between the tearing energy. T, and the crack growth per cycle, dc/dn. The increment of crack growth during each cycle is shown here to result from the sum of time dependent and cyclic crack growth components. The time dependent component represents the crack growth behavior that would be present in a conventional constant T erack growth test. Under repeated stressing additional crack growth, termed the cyclic crack growth component, occurs. For a non-crystallizing elastomer, significant effects of frequency have been found on the cyclic crack growth behavior, reflecting the presence of this cyclic element of crack growth. The cyclic crack growth behavior over a wide range of frequencies was investigated for unfilled and swollen SBR materials. The lime dependent crack growth component was calculated from constant T crack growth tests and the cyclic contribution derived from comparison with the observed cyclic growth. It is shown that decreasing the frequency or increasing the maximum tearing energy during a cycle results in the cyclic crack growth behavior being dominated by time dependent crack growth. Conversely at high frequency and at low tearing energy, cyclic crack growth is dominated by the cyclic crack growth component. A large effect of frequency on cyclic crack growth behavior was observed for highly swollen SBR. The cyclic crack growth behavior was dominated by the time dependent crack growth component over the entire range of tearing energy and/or crack growth rate. The origin of the cyclic component may be the formation/melting of quasi crystals at the crack tip, which is absent at fast crack growth rates in the unswollen SBR and is absent at all rates in the swollen SBR.
TL;DR: In this article, the hydrodynamic dispersion of spherical calcium carbonate agglomerates was studied under both steady and oscillatory shear-flow conditions, and the dispersion kinetics were also affected by the extent of matrix infiltration.
Abstract: The hydrodynamic dispersion of spherical calcium carbonate agglomerates was studied under both steady and oscillatory shear-flow conditions. For a given intensity of steady shear flow, erosion rates were strongly influenced by the cohesive strength of the agglomerates with less cohesive, low-density agglomerates exhibiting faster erosion than high-density agglomerates. The dispersion kinetics were also affected by the extent of matrix infiltration within the agglomerate, with more infiltration resulting in reduced erosion rates. Experiments conducted in oscillatory shear flow fields provided new insights on local mechanisms of erosion.
TL;DR: In this paper, a simplified and realistic kinetic scheme was proposed for the cure reversion mechanism of accelerated sulfur vulcanization for gum natural rubber (NR) compounds, and the vulcametric curves at different temperatures were simulated from curing to overcuring periods by using a kinetic approach.
Abstract: A simplified and realistic kinetic scheme was proposed for the cure reversion mechanism of accelerated sulfur vulcanization for gum natural rubber (NR) compounds. The vulcametric curves at different temperatures were simulated from curing to overcuring periods by using a kinetic approach. The different rate constants and activation energies were calculated from the simulation process. The simulated results showed a good agreement with isothermal vulcametric data over a wide range of temperatures and showed that the relationships between the rate constants and the cure temperatures were in accordance with the Arrhenius Equation. The activation energies (Ea1, Ea2, and Ea3) of the formation, desulfurization and decomposition of polysulfidic crosslink obtained from Arrhenius plots were 79.5,102.6 and 138.8 kJ/mol, respectively. The experimentally measured crosslink densities determined by using swelling equilibrium and chemical probe techniques agreed with the simulated vulcametric curves to some extent.
TL;DR: In this paper, an investigation on in situ polymerization of styrene in deproteinized natural rubber (DPNR) latex and high ammonia Natural Rubber (HANR) latex was carried out, and it was observed that at reaction temperature of 60 °C and reaction time of 10 hours, the styrene-DPNR system could attain a high conversion of 97% without adding surfactant.
Abstract: An investigation on in situ polymerization of styrene in deproteinized natural rubber (DPNR) latex and high ammonia natural rubber (HANR) latex was carried out. The ratio of styrene to dry rubber was fixed at 25 : 75 by weight. It was observed that, at reaction temperature of 60 °C and reaction time of 10 hours, the styrene-DPNR system could attain a high conversion of 97% without adding surfactant. The degree of chemical bonding estimated for the resultant polystyrene-DPNR dried material was about 80%. The styrene-HANR system, however, required the addition of surfactant to complete the reaction time; but the conversion was found to be relatively low, in the region of 66%. This low conversion could be attributed to the role played by the protein/lipid layer, which is virtually absent in the styrene-DPNR system.
TL;DR: In this article, the authors separated the Rubbers from small and large rubber particles from the serum and cream phases of centrifuged fresh Hevea latex, respectively, and found that the serum rubber was soft and viscous rubber differing from the cream rubber containing in LRP.
Abstract: The rubbers from small and large rubber particles were separated from the serum and cream phases of centrifuged fresh Hevea latex, respectively. The small rubber particles (SRP) consist of rubber molecules showing a unimodal molecular weight distribution (MWD), with a peak-top value falling between the two peak values of the bimodal MWD observed in rubbers from the large rubber particles (LRP). The rubbers in LRP from mature trees and SRP from seedlings are polyisoprene molecules terminated by phospholipids comprising branching points, while those in SRP from mature trees are presumed to be linear molecules containing no phospholipid terminal. The serum rubber was found to be soft and viscous rubber differing from the cream rubber containing in LRP. Thus, it can be presumed that the particle size of rubber latex is an important parameter influencing the MW, MWD and physical properties of Hevea rubber.
TL;DR: In this paper, azo group serves as a "smart interface" in that it is responsive to heat and thermally severing the azo linkage can determine the influence of interfacial bonding on properties independent of other morphological factors.
Abstract: Silica-reinforced siloxane composites are synthesized with heat labile azo groups at the polymer-filler interface. The azo group serves as a “smart interface” in that it is responsive to heat. This system is used to assess the influence of interfacial chemical bonds on mechanical properties. By thermally severing the azo linkage, we can determine the influence of interfacial bonding on properties independent of other morphological factors. The virgin filler powders, azo-modified powders, silica-filled composites and azo-modified-silica-filled composites are characterized using small-angle x-ray scattering, IR spectroscopy, and scanning electron microscopy. Mechanical properties are correlated with the presence or absence of interface coupling, filler loading and thermal exposure. The data show that, at loadings above 5 wt%, elongation is enhanced in the azo-linked composites compared to the composites with bare fillers; modulus is enhanced at low silica loadings (<5wt%) but is reduced at high loa...
TL;DR: In this article, the role of filler morphology in elastomer reinforcement was investigated using x-ray, light and neutron scattering to determine the structure of precipitated silica powders.
Abstract: In an attempt to elucidate the role of filler morphology in elastomer reinforcement, we use x-ray, light and neutron scattering to determine the structure of precipitated silica powders. We find the signatures of at least three levels of structure: primary particles, aggregates and agglomerates. By observing the evolution of the scattering profile during solution synthesis, we are able to identify when these structures appear. We also investigate the effect of ionic strength on morphology and find evidence for the interpenetration of aggregates on drying of powders prepared at low ionic strength. Using a reinforcement model by Witten, Rubinstein and Colby, we conclude that the ideal filler will consist of soft agglomerates made up of hard aggregates. Based on the dependence of morphology on synthetic protocol, we present strategies for design of efficient reinforcing fillers.
TL;DR: In this article, the structural changes that occur during the accelerated sulfur vulcanization of styrene-butadiene rubbers (SBR) through characterization of the network sulfide struct...
Abstract: This paper discusses the structural changes that occur during the accelerated sulfur vulcanization of styrene-butadiene rubbers (SBR) through characterization of the network sulfide struct...
TL;DR: In this paper, the effect of nonhomogeneities on the shearing response of an isotropic, incompressible neo-Hookaan slab is investigated, and the results show that the shear strain is more inhomogeneous and localized for the slabs with a great degree of spatial nonhomogenity.
Abstract: Vulcanized rubber components possess material non-homogeneities due to either non-uniform vulcanization during their fabrication or attack of thermal and oxidative environments durding their service life. The primary objective of this paper is to theoretically inveslighte the effect of a material non-homogencity on the shearing response of an isotropic, incompressible neo-Hookaan slab. The non-homogeneity considered in the slab is the spatially varying shear modulus that is approximately described by a spatial-distribution function. A parabolic and a boundary layer-like spatial-distribution function are assumed; then exact solutions for the stress-strain fields in the slab are obtained by solving the liness momentum balssex equations based on a postulated inhomogeneous shearing deformation. Our theoretical results show that the shear strain is more inhomogeneous and localized for the slabs with a greates degree of spatial non-homogencity. In the non-homogetneous slab, we have also determined the existence of a uniform shear stress and an inhomogeneous first normal-stress difference whose variation is similar to that of the shear strain. The implications of these results are considered in terms of the fabrication, performance and mechanical characterization of the rubber-elastic materials.