Abstract

Polyamide fibers are melt spun from linear semicrystalline thermoplastic polymers having recurring amide groups made from diamines and dicarboxylic acids or lactams. Poly(hexamethyleneadipamide), designated as nylon-6,6, and poly(caprolactam), nylon-6, account for 98% of the 4 million metric tons of the worldwide annual production of nylon fiber. The attributes of nylon such as high strength, durability, abrasion resistance, resilience, moderate hydrophilicity, ease of dyeability, and low specific gravity have been recognized since its introduction in 1938. Both the inherent properties and those properties that can be engineered into the fiber manufacturing and ultimately into the fabric in downstream mill processing combined with reasonable market pricing account for the diverse end uses and market longevity of nylon. Nylon fiber is offered in the forms of continuous flat and textured filaments, staple, tow and flock for hosiery, apparel, home, flooring, industrial and transportation fabric applications. The physical appearance, functionality, and end-use performance of nylon fibers can be modified by incorporating additives, eg, delusterants, colorants, antioxidants, or antistats in the polymer, by designing a spinneret hole configuration to impart a desired luster, surface effect or specific dtex-per-filament, by spinning bicomponent or biconstituent fibers, and by chemically or mechanically treating the surface of the fiber or fabric.