Abstract: The present invention provides a crosslinked polymer composition exhibiting significantly improved elongation at break over conventional ones, and a polymer composition and a polyrotaxane, each of which can be used as a raw material of the crosslinked polymer composition. The polyrotaxane contains a linear molecule, a cyclic molecule, and a blocking group, wherein the cyclic molecule has a hydrosilyl group. The polymer composition contains the polyrotaxane and a polymer, wherein the polymer has a double bond on at least either a main chain or a side chain. The crosslinked polymer composition is produced by crosslinking of the polymer composition through chemical reaction between the hydrosilyl group of the cyclic molecule and the double bond of the polymer.

Abstract: A crosslinked rubber composition contains ethylene-propylene-diene copolymer rubber crosslinked with a rotaxane compound having a cyclic molecule and an axial molecule penetrating through the cyclic molecule. In the crosslinked rubber composition, the ethylene-propylene-diene copolymer rubber contains vinylnorbornene, dicyclopentadiene, or tetrahydroindene as a diene component, and the rotaxane compound has a nitrile oxide group on the cyclic molecule and one end of the axial molecule, and the cyclic molecule is crown ether.

Abstract: A crosslinked rubber composition contains ethylene-propylene-diene copolymer rubber crosslinked with a rotaxane compound having a cyclic molecule and an axial molecule penetrating through the cyclic molecule. In the crosslinked rubber composition, the ethylene-propylene-diene copolymer rubber contains vinylnorbornene, dicyclopentadiene, or tetrahydroindene as a diene component, and the rotaxane compound has a nitrile oxide group on the cyclic molecule and one end of the axial molecule, and the cyclic molecule is crown ether.

Abstract: A rubber includes 5 parts by mass to 45 parts by mass of an uncross-linked EPM relative to 100 parts by mass of a cross-linked rubber polymer (other than EPM), and an oil in an amount equal to or more than the amount of the EPM. The rubber is foamed and has a specific gravity of more than 0.3 and 0.8 or less. A weather strip 1 and a hose 2 are formed of the rubber.

Abstract: A foam rubber molded produce obtained by molding a rubber composition containing 100 parts by mass of ethylene-?-olefin-nonconjugated diene copolymer, 4 to 30 parts by mass of amorphous 4-methyl-1-pentene copolymer, 2 to 8 parts by mass of blowing agent, and a sulfur-based vulcanizing agent, and having a Mooney viscosity after kneading (ML1+4, 100° C.) of 54 or less. A specific gravity is 0.3 to 0.8, a compression set is less than 27%, and a foam state is an interconnected cell.

Abstract: A foam rubber molded produce obtained by molding a rubber composition containing 100 parts by mass of ethylene-?-olefin-nonconjugated diene copolymer, 4 to 30 parts by mass of amorphous 4-methyl-1-pentene copolymer, 2 to 8 parts by mass of blowing agent, and a sulfur-based vulcanizing agent, and having a Mooney viscosity after kneading (ML1+4, 100° C.) of 54 or less. A specific gravity is 0.3 to 0.8, a compression set is less than 27%, and a foam state is an interconnected cell.

Abstract: A rubber includes 5 parts by mass to 45 parts by mass of an uncross-linked EPM relative to 100 parts by mass of a cross-linked rubber polymer (other than EPM), and an oil in an amount equal to or more than the amount of the EPM. The rubber is foamed and has a specific gravity of more than 0.3 and 0.8 or less. A weather strip 1 and a hose 2 are formed of the rubber.