Synthetic fiber made from acrylonitrile copolymers with acrylonitrile or polyacrylonitrile content greater than 85% (by weight). 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 100 years ago, polyacrylonitrile was produced, but due to the lack of a suitable solvent, it couldn't be spun into fibers. In 1942, German H. Rein and American G.H. Linstead discovered dimethylformamide solvent almost simultaneously and successfully produced polyacrylonitrile fibers. In 1950, DuPont in the U.S. initiated industrial production. Subsequently, various solvents were discovered, leading to multiple production processes. In 1954, the German company Farbenfabriken Bayer used copolymers of methyl methacrylate and acrylonitrile to produce fibers, improving fiber properties and practicality, thus promoting the development of polyacrylonitrile fibers. In 1984, the global production of polyacrylonitrile fibers reached 2.4 million tons.