Abstract: A crosslinked foamed body obtained by subjecting a rubber compounded product comprising (A) a chlorinated ethylene/.alpha.-olefin copolymer rubber, (B) a triazinethiol as a vulcanization agent, (C) an alkyl ammonium halide as a vulcanization promotor, and (D) a hydrazide-type blowing agent to two step vulcanization and foaming at a vulcanization temperature of 120.degree. to 140.degree. C. for a vulcanization time of 5 to 10 minutes in a first step and at a vulcanization temperature of 125.degree. to 160.degree. C. for a vulcanization time of 5 to 20 minutes in a second step, the second step vulcanization temperature being higher than the first step by at least 5.degree. C., so that the expansion factor will be 3 to 10 times. This crosslinked foamed body can be colored brilliantly, exhibit excellent weatherability, suppleness and shape retention as well as good outer appearance. This product is well usable, for example, as wet suits.

Abstract: There have been provided by the present invention a higher .alpha.-olefin copolymer which has an intrinsic viscosity [.eta.], as measured in decalin at 135.degree. C., of 0.1 to 10 dl/g, and comprises polymer units derived from 95-30 parts by mol of a higher .alpha.-olefin of C.sub.6-20, 5-70 parts by mol of an aromatic ring-containing vinyl monomer represented by the formula [I] (total of the higher .alpha.-olefin and the vinyl monomer are 100 parts by mol), and 0.01 to 30% by mol of a non-conjugated diene represented by the formula [II]; ##STR1## wherein n is an integer of 0 to 5, and R.sup.1, R.sup.2 and R.sup.3 are each independently H or C.sub.1-8 alkyl; ##STR2## wherein n is an integer of 1 to 5, R.sup.4 is C.sub.1-4 alkyl, R.sup.5 and are each independently H or C.sub.1-8 alkyl but are not H simultaneously, a process for the preparation thereof, a higher .alpha.-olefin copolymer composition comprising [A] the higher .alpha.