Aramid

Aramid is a strong, heat-resistant synthetic material developed by American Stephanie Kwolek in 1961. It is used in the aerospace industry and the military, for the production of bulletproof vests, and as a substitute for asbestos. The name is a shortened form of "aromatic polyamide."

It is produced by spinning a strong fiber from a liquid solution, which is enabled by the ionic component of the reaction mixture (calcium chloride), which binds to the hydrogen bridges of the amide groups, and the choice of an organic solvent (N-methylpyrrolidone).

The greatest advantages of aramid include, for example, that it is difficult to ignite and the fact that it is a non-conductive material. Additionally, its high strength and high Young's modulus of elasticity can be highlighted. It is also sensitive to ultraviolet radiation, and can be well processed in factories at elevated temperatures. Among the most common industrial uses of aramid are fire-resistant clothing, tire reinforcements, and other rubber products, sporting equipment, and many others.

The most well-known aramid fiber (para-amid nylon) is Kevlar, its version from the company Teijin called Twaron and its fire-resistant variant Nomex. According to the Federal Trade Commission (The US Federal Trade Commission), aramid fiber is defined as "a fiber made from polyamide with a long hydrocarbon chain, of which at least 85% of the peptide bonds are attached to two aromatic rings."

Kevlar is used wherever exceptionally high strength and exceptional thermal resistance are needed. Keeps its strength and flexibility even at cryogenic temperatures (-196 °C); it is even slightly stronger at low temperatures. Kevlar is used in parts of aircraft and space shuttles, brake components and landing gears, bulletproof vests, anti-mine boots, transmission belts, optical and telecommunication cables, protective helmets, various types of sports equipment, and a wide range of other applications.

At high temperatures, tensile strength is reduced by 10-20%, and after a few hours, the strength decreases further. For example, at 160 °C, a 10% reduction in strength occurs after 500 hours. At 260 °C, a 50% reduction in strength occurs after 70 hours. At 450 °C, Kevlar sublimates. The ultraviolet component of sunlight degrades and decomposes Kevlar, which is why it is rarely used in outdoor applications without protection from sunlight. Disadvantages include low resistance to ultraviolet radiation and moisture and difficult dyeing ability.