NYLON

any synthetic plastic material composed of polyamides of high molecular weight and usually, but not always, manufactured as a fibre. Nylons were developed in the 1930s by a research team headed by an American chemist, Wallace H. Carothers, working for E.I. du Pont de Nemours & Company. The successful production of a useful fibre by chemical synthesis from compounds readily available from air, water, and coal or petroleum stimulated expansion of research on polymers, leading to a rapidly proliferating family of synthetics. Nylon can be drawn, cast, or extruded through spinnerets from a melt or solution to form fibres, filaments, bristles, or sheets to be manufactured into yarn, fabric, and cordage; and it can be formed into molded products. It has high resistance to wear, heat, and chemicals. When cold-drawn, it is tough, elastic, and strong. Most generally known in the form of fine and coarse filaments in such articles as hosiery, parachutes, and bristles, nylon is also used in the molding trade, particularly in injection molding, where its toughness and ability to flow around complicated inserts are prime advantages. Polyamides may be made from a dicarboxylic acid and a diamine or from an amino acid that is able to undergo self-condensation, or its lactam, characterized by the functional group -CONH- in a ring, such as e-caprolactam. By varying the acid and the amine, it is possible to make products that are hard and tough or soft and rubbery. Whether made as filaments or as moldings, polyamides are characterized by a high degree of crystallinity, particularly those derived from primary amines. Under tension, orientation of molecules continues until the specimen is drawn to about four times its initial length, a property of particular importance in filaments. Two of the ingredients that are used to synthesize the most common nylon, adipic acid and hexamethylenediamine, each contain six carbon atoms, and the product has been named nylon-6,6. When caprolactam is the starting material, nylon-6 is obtained, so-named because it has six carbon atoms in the basic unit.