MetaAramiden

Metaaramiden, commonly referred to as meta-aramids, are a family of aramid (aromatic polyamide) polymers in which the amide linkages connect benzene rings at meta positions. In English-language literature the standard term is meta-aramid; metaaramiden appears in some non-English sources or as a plural form. The best-known meta-aramid fiber is Nomex.

Chemistry and production of meta-aramids involve polycondensation to form poly(meta-phenylene isophthalamide). A typical synthesis uses m-phenylenediamine as the diamine component and isophthaloyl chloride as the diacid chloride component, producing high-molecular-weight polymers that can be spun into fibers. The meta orientation of the linkages distinguishes them from para-aramids, which use para-oriented linkages and include fibers such as Kevlar.

Properties of meta-aramids include high thermal stability, flame resistance, and low smoke generation when exposed to fire. They generally maintain mechanical properties at elevated temperatures and exhibit good chemical resistance and dimensional stability. Compared with para-aramids, meta-aramids often show lower tensile strength and modulus but superior resistance to heat-induced deformation and certain solvents.

Applications focus on flame- and heat-resistant materials. They are widely used in protective clothing for firefighters, industrial workers, and electrical workers, as well as in heat shields, insulation, and some filtration and automotive applications. The term meta-aramid encompasses several commercial grades and brands produced by multiple manufacturers, with Nomex being the most prominent example.

See also: aramid, para-aramid, Nomex, Kevlar.