polyaramid

Polyaramid refers to a family of high-performance aromatic polyamides characterized by amide linkages between rigid, aromatic rings. The rigid backbone gives polyaramids high strength and modulus at relatively low density, making them suitable for fibers, films, and reinforced composites. They also exhibit good thermal stability and chemical resistance.

Two major subclasses are para-aramids and meta-aramids. Para-aramids, made from p-phenylenediamine and terephthaloyl chloride, form fibers with very high tensile strength and stiffness and are widely used as reinforcing fibers in composites and in protective textiles. Meta-aramids, produced from m-phenylenediamine and isophthaloyl chloride, offer superior heat resistance and oxidative stability but lower mechanical strength, and are commonly used in flame-retardant clothing, high-temperature insulation, and certain protective applications.

Properties of polyaramids include high mechanical strength and stiffness, low density, and excellent abrasion and chemical resistance. They maintain performance over a broad temperature range, though they can be sensitive to prolonged UV exposure and may require careful processing to preserve crystallinity and fiber integrity.

Applications span protective equipment and specialty textiles to industrial reinforcements and insulation. They are used in body armor, firefighter and cut-resistant garments, aerospace and automotive composites, reinforced tires, electrical insulation, hoses, and filtration media. Notable products include Kevlar (para-aramid), Nomex (meta-aramid), and Twaron (para-aramid).