"lpyrrolidones (cross-linked and otherwise); polymers and copolymers of vinyl monomers including polyvinyl alcohols, polyvinyl halides such as polyvinyl chlorides, ethylene-vinylacetate copolymers (EVA), polyvinylidene chlorides, polyvinyl ethers such as polyvinyl methyl ethers, styrene polymers and copolymers such as polystyrenes, styrene-maleic anhydride copolymers, styrene-butadiene copolymers," . . . .