polyakrylnitril

Polyakrylnitril, more commonly known as polyacrylonitrile (PAN), is a synthetic polymer produced from the monomer acrylonitrile. Its repeating unit is −CH2−CH(CN)−. PAN is a rigid, highly polar polymer with notable thermal stability and chemical resistance. It is particularly valued as a precursor for carbon fibers, but is also used in specialty fibers and membranes.

Production and processing: PAN is formed by free-radical polymerization of acrylonitrile, typically in solution, emulsion, or suspension polymerization. commercial PAN often includes small amounts of comonomers to improve spinnability or tailor the properties of the final material. Spinning PAN fibers generally relies on solution-based methods such as wet-spinning, rather than melt-spinning, because PAN resists melting and tends to decompose at elevated temperatures.

Properties and forms: PAN can be processed into fibers, films, and membranes. It has a high glass transition temperature and strong intermolecular interactions due to the nitrile groups, which confer chemical resistance and mechanical stiffness. The material’s properties can be adjusted by copolymerization or blending, and by post-processing treatments such as stabilization and carbonization when used as a carbon-fiber precursor.

Applications: The dominant use of PAN is as a precursor for carbon fibers, which are stabilized in air and then carbonized to produce high-strength, lightweight fibers used in aerospace, automotive, and sporting goods. PAN is also employed in specialty fibers for textiles, as well as in gas-separation membranes and filtration media, depending on molecular weight, copolymer composition, and processing.

Safety and environment: Acrylonitrile, the monomer, is toxic and potentially carcinogenic, requiring stringent safety and emission controls in manufacturing. PAN itself is relatively stable but combustion can release hazardous nitrogen-containing gases.