a synthetic fiber produced from melts or solutions of polyamides. Polyamide fibers are usually produced from linear aliphatic polyamides, most often polycaproamide and polyhexamethylene adipamide, with molecular weights varying from 15,000 to 30,000. The manufacture of fibers made from aromatic polyamides possessing high thermal stability was begun in the late 1960’s. The production of polyamide fibers consists of three major stages: production of the polymer, molding of the fiber, and conversion of the fiber into fabric.
Polyamide fibers are characterized by high tensile strength and excellent resistance to wear and impact. They are stable to the action of many chemical reagents and biochemical agents, and they have an affinity to many dyes. The maximum operating temperature of fibers made from aliphatic polyamides is 80–150°C, and of fibers made from aromatic polyamides, 350°–600°C. The fibers dissolve in concentrated mineral acids, phenol, cresol, trichloroethane, and chloroform.
Polyamide fibers have low hygroscopicity, as a result of which they tend to become electrically charged. They have poor resistance to thermal oxidation and the action of light, especially ultraviolet radiation. Various stabilizers are added to eliminate these disadvantages.
Polyamide fibers are used in the manufacture of common household items, tire cord, rubber products, filters, fishing nets, brushes, and cables. Textured threads made from polyamide fibers have become common.
Polyamide fibers are produced in filament or staple form in many countries under various trade names. Fibers made from polycaprolactam include Kapron (USSR), Nylon-6 (USA), Perlon (Federal Republic of Germany), Dederon (German Democratic Republic), and Amilan (Japan). Among the fibers made from polyhexamethylene adipamide are Anid (USSR), Nylon-6,6 (USA), Rhadia-Nylon (Federal Republic of Germany), and Niplon (Japan). Fibers made from aromatic polyamides include Nomex (USA).
The world production of polyamide fibers in 1975 was about 2.5 million tons.