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

Over a century ago, polyacrylonitrile was synthesized, but due to the lack of a suitable solvent, it could not be made into fibers. In 1942, Germans H. Rein and Americans G.H. Linstead discovered dimethylformamide solvent almost simultaneously and successfully produced polyacrylonitrile fibers. In 1950, the American DuPont Company was the first to initiate industrial production. Subsequently, various solvents were found, leading to multiple production processes. In 1954, the German chemical company Hoechst AG used a copolymer of methyl acrylate and acrylonitrile to produce fibers, 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.