Examples of such polymers are polyolefins such as low, medium, and highdensity polyethylenes, polypropylene, polybutene-1, poly (dodecamethylene pyromellitimide), ethylene-propylene copolymers, and terpolymers with non-conjugated dienes, fluoropolymers such as the homopolymers of chlorotrifluoroethylene, vinyl fluoride andvinylidene fluoride and the copolymers of vinylidene fluoride-chlorotrifluor