Better foamable styrene and other olefin polymer compositions

Claim 1

A lightly cross-linked expanded foam product of the composition comprising, in intimate admixture: (a) as a fundamental constituent, a hydroxylated, normally solid, linear polymer selected from the group consisting of linear olefin polymers, linear alkenyl aromatic copolymers, which is a polymerizate containing at least about 60 percent by weight, based on total polymer weight (i.e., "weight percent") of at least one polymerizable monomer of the general Formula: ##STR5## wherein: G is selected from the group consisting of hydrogen and methyl; and Ar is an aromatic radical, including alkyl and halo-ring-substituted aromatic units, that contains from 6 to about 10 carbon atoms; with the balance being copolymerized units of another addition polymerizable monomer or monomer mixture that is copolymerizable with styrene, the copolymer having a hydroxyl functionality of from 2 to 6average hydroxyl groups per unit weight average molecule; and (b) a substantially minor proportion of an inter-reactive crosslinking polyisocyanate constituent, with the further limitation that the copolymer have a crosslinking coefficient of from about 0.8 to about 3 which results in a visually detectable gel in a solvent which dissolves the corresponding noncrosslinked hydroxylated polymers, and that such composition on incorporation of a blowing agent therein is foamable to a thermal collapse resistant thermoplastic foam.