Synthetic fibers made from acrylonitrile copolymers with a content of acrylonitrile or polyacrylonitrile exceeding 85% (by weight percentage). Common monomers include non-ionic monomers such as methyl acrylate, methyl methacrylate, etc., with the third monomer being an ionic monomer like sodium acrylate.

More than a century ago, polyacrylonitrile was produced, but due to the lack of a suitable solvent, it could not be spun into fibers. In 1942, German H. Rein and American G.H. L瑟姆 almost simultaneously discovered dimethylformamide as a solvent, and successfully produced polyacrylonitrile fibers. In 1950, the American DuPont Company was the first to initiate industrial production. Subsequently, various solvents were discovered, leading to multiple production processes. In 1954, the German company Hoechst AG developed fibers from a copolymer of methyl acrylate and acrylonitrile, improving fiber properties, enhancing practicality, and promoting the development of polyacrylonitrile fibers. In 1984, the global production of polyacrylonitrile fibers reached 2.4 million tons.