PBI

Polybenzimidazole fibers (PBI) are a class of extremely heat-resistant synthetic fibers. They are formed from completely aromatic polyamides. They are fibers in which the fiber-forming substance is a long-chain aromatic polymer having recurring imidazole groups as one of the main structural repeat units in the polymer backbone.
 

PBI is prepared from an aromatic tetraamine and an aromatic dicarboxylic acid or a derivative of it. The resin is then spun into fibers via a dry spinning process using dimethyl acetamide as a solvent.
 

PBI fibers are rather expensive and difficult to manufacture, but have some of the best fiber properties. Due to the fully aromatic structure, PBI has a very high glass transition temperature (425°C) and no melting point.
Its heat deflection temperature at 1.8 MPa is about 435°C. The fiber also possesses outstanding heat stability and chemical resistance, including alcohols, hydrocarbons, chlorinated solvents, hydrogen sulfide, weak acids and bases, and many other chemicals. Its decomposition temperature is more than 700°C.