Yours, Etc.: Origins and Uses of 8 Sign-Offs
any of a class of resinous, fibrous, or rubbery substances belonging to the family of organic polymers based on acrylonitrile. Almost all polyacrylonitrile resins are copolymers (q.v.), made from mixtures of monomers, with acrylonitrile (see nitrile) usually making up the major portion; other monomers often present include butadiene, styrene, vinylidene chloride, or other vinyl compounds.