. "Among the homopolymers suitable for use as the non-elastomeric second polymer component can be included polyvinyl acetate, polymethylmethacrylate, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyesters such as polyethyleneterephthalate, polyamides, polyaldehydes, polyolefins including polyhalohydrocarbons, etc." . . .