Aramida

Aramida, or aramid, is a family of synthetic polymers characterized by aromatic rings in their backbone and amide linkages. The term aramid derives from aromatic polyamide. Aramids are known for high tensile strength, stiffness, and resistance to heat, making them suitable for protective gear and reinforced composites. They typically come in two major classes: para-aramids (PPTA) and meta-aramids (MPA).

Para-aramids include Kevlar and Twaron; they offer very high strength and modulus, excellent abrasion resistance, and low creep. They do not melt; instead, they char or decompose at elevated temperatures, retaining strength up to several hundred degrees. Meta-aramids such as Nomex provide better flame resistance and thermal stability at higher temperatures but lower strength and stiffness. They are widely used in flame-resistant clothing, insulating materials, and various industrial applications.

Production involves polycondensation to form rigid aromatic polyamides. PPTA is formed from p-phenylene diamine and terephthaloyl chloride; meta-aramids from m-phenylene diamine and isophthaloyl chloride. The polymer is dissolved in a suitable solvent and spun into fibers, then drawn to achieve high orientation and strength.

Applications are broad and include ballistic protection, helmets, protective clothing, ropes and cables, tires reinforcement, aerospace and automotive composites, and filtration materials. The development of aramids began in the 1960s, with Kevlar introduced by DuPont in 1965 and Nomex in 1969; Twaron and Technora followed in later decades. Aramids are valued for their strength-to-weight and heat resistance but face recycling challenges and sensitivity to UV exposure and certain chemicals.