Nylon

Nylon, a synthetic polymer widely used for textile fibres, characterized by great strength, toughness, and elasticity, and processed also in the form of bristles and moulded articles. Nylon was developed in the 1930s by scientists of E. I. du Pont de Nemours and Company, Inc., headed by the American chemist Wallace Hume Carothers. It is usually made by polymerizing adipic acid and hexamethylenediamine, an amine derivative (see Polymer: Synthesis). Adipic acid is derived from cyclohexane by an oxidation reaction that opens up the ring of carbon atoms; hexamethylenediamine is made by treating adipic acid catalytically with ammonia and hydrogenating the product (see Hydrogenation). Nylon is insoluble in water and in ordinary organic solvents; it dissolves in phenol, cresol, and formic acid, and melts at 263° C (505° F).

In making textile fibres, small chips of the nylon polymer, which is obtained as a tough, ivorylike material, are melted and forced through holes in a metal disc called a spinneret. The filaments are congealed by a blast of air and are then drawn to about four times their original lengths. The diameter of the filaments is controlled by changing the rate at which the molten nylon is pumped into the spinneret and the rate at which the filaments are drawn away. Filaments much finer than those of ordinary textile fibres can be made from nylon. Nylon fibres can have the appearance and lustre of silk or can be made to resemble natural fibres such as cotton; their tensile strength is higher than that of wool, silk, rayon, or cotton. Dyes are applied either to the molten mass of nylon or to the yarn or finished fabric. Acetate rayon dyes are usually used for nylon.

Nylons made from other acids and amines resemble, in general, the nylon described above.

Nylon is used in the manufacture of fabrics for such articles as hosiery, sleepwear, underwear, blouses, shirts, and raincoats. Nylon fabrics are water-resistant; they dry quickly when laundered and usually require little or no ironing. Nylon fibres are also used for parachutes, insect screening, medical sutures, strings for tennis rackets, brush bristles, rope, and fishing nets and line. Moulded nylon is used for insulating material, combs, kitchen utensils, and machinery parts.