Nylon is a polyamide fiber, derived from a diamine and a dicarboxylic acid. There are very large numbers of polyamide materials available to produce nylon fibers, as a variety of diamines and dicarboxylic acids can be used as starting materials. It was the first truly synthetic fiber to be commercialized (1939). Nylon was developed in the 1930s by scientists at Du Pont, headed by an American chemist Wallace Hume Caruthers (1896-1937). The two most commonly used synthetic polyamides are nylon 66 (polyhexamethylene adiamide) and nylon 6 (Polycaprolactam, a cyclic nylon intermediate). The chemical reactions involved in the polymerization are as follows.