Abstract: A rubber composition obtained by subjecting a mixture of (I) 35-95 parts by weight of a fluoroelastomer, (II) 65-5 parts by weight of at least one member selected from the group consisting of polyethylene, ethylene-vinyl acetate copolymer and ethylene-unsaturated carboxylic acid ester copolymer, and an organic peroxide to reaction while imparting shearing deformation to the mixture. A crosslinkable rubber composition can be obtained by compounding the above rubber composition with a crosslinking agent for the fluoroelastomer (I). The above rubber composition is superior in processability, particularly extrusion-processability, sealing property, heat resistance, steam resistance and weather resistance.

Abstract: A rubber composition comprising 100 parts by weight of a rubber component which comprises at least 30% by weight of an emulsion polymerization rubber which is a conjugated diene polymer rubber or conjugated dienestyrene copolymer rubber obtained by emulsion polymerization, has a bound styrene content of 0-65% by weight, contains 20-35% by weight of a component having a molecular weight of not more than 150,000 as measured by a gel permeation chromatography and has a Mooney viscosity, ML.sub.1+4 (100.degree. C.), of 60-160 and a Mooney viscosity difference (.DELTA.MV) of -20 to +5 as defined by the following equation:.DELTA.MV=ML.sub.1+4 (100.degree. C.)-ML.sub.1+15 (100.degree. C.)and 45-200 parts by weight of carbon black. Said rubber composition is excellent in abrasion resistance, breaking strength and high histeresis property in uses in which carbon black or oil is blended at a high-filling rate.

Abstract: A thermoplastic elastomer composition consisting essentially of (A) 2 to 50% by weight of a polybutadiene having a 1,2-addition unit content of 70% or more, (B) 20 to 90% by weight of an olefinic rubber and (C) 5 to 60% by weight of a polyolefin resin, 30 to 95% by weight of the total polymer components, up to 90% by weight of said polybutadiene and up to 90% by weight of said olefinic rubber being soluble in Tetralin when the composition is heated at 210.degree. C for 3 hours in Tetralin under reflux. Said composition is excellent in mechanical strength, weather resistance, oil resistance, heat stability and processability and has a small permanent set.