Metaaramid

Metaaramid is a class of aramid polymers in which the amide linkages connect phenyl rings at the meta position, as opposed to the para position found in para-aramids. The most well-known example is poly(m-phenylene isophthalamide), a meta-aramid marketed under names such as Nomex. Meta-aramids are typically formed by polycondensation of m-phenylenediamine with isophthaloyl chloride and are processed into fibers or films by solution-spinning rather than melt-spinning due to their high thermal stability.

In terms of processing and structure, meta-aramids are rigid-rod polymers with high thermal resilience. They are designed to retain structural integrity at elevated temperatures and are often flame-retardant and low in smoke production. They tend to form char when exposed to flame rather than melting, which contributes to their protective performance in fire environments. Compared with para-aramids, meta-aramids generally exhibit lower tensile strength and modulus but greater elongation and flexibility, along with excellent flame resistance and heat stability in air.

Applications of metaaramids are primarily in areas where flame resistance and high-temperature performance are essential. Common uses include protective clothing for firefighters and industrial workers, heat-insulating fabrics, electrical and thermal insulation, and filtration media. They are also employed in certain reinforced composites and components where flame retardancy is a critical requirement. Nomex remains the archetypal meta-aramid fiber, widely used in protective gear and related textiles.