"Such materials as polyvinyl chloride, polyvinylidene fluoride, chlorinated polyethylene and polymers of such materials as vinylidene fluoride, vinylidene fluoride and chlorotrifluoroethylene, chlorotrifluoroethylene and vinylidene fluoride, chlorotrifluoroethylene and vinyl chloride, chlorotrifluomethylene-vinylidene fluoride and tetrafluoroethylene and the like." . . . . . .