. . . "nylidene monomers such as ethylene, propylene, vinyl chloride, vinylidene chloride, vinylidene cyanide, acrylonitrile, methyl acrylate, and the like, e.g. polyethylene, polypropylene, vinyl chloridevinylidene chloride copolymer, acrylonitrile-methyl acrylate copolymer, and the like; or even inorganic fibers such as glass, metal, and the like." . .