chemical fibers produced from natural organic polymers, including viscose fibers, cuprammonium fibers, acetate fibers, and synthetic protein fibers. The viscose and cuprammonium fibers, which consist of hydrated cellulose, are also called hydrated cellulose fibers. The raw material for producing viscose, cuprammonium, and acetate fibers is the cellulose obtained from wood; cuprammonium and acetate fibers are frequently prepared from cotton cellulose (cotton fluff and linter). Protein fibers are produced from vegetable or animal protein (zein and casein). Man-made fibers are formed from polymer solutions by the dry or wet methods and are produced as textile or cord filaments and as staple fiber.
The disadvantages of viscose, cuprammonium, and protein fibers include a considerable loss of strength when wet and low wrinkle resistance. However, owing to their good hygienic properties, their low cost, and the availability of raw material, the production of viscose fiber continues to in-crease. The production of acetate fibers, which have a number of valuable properties (wrinkle resistance and attractive appearance), is also increasing. Protein fibers are being produced in small quantities, and their production is decreasing gradually.
The world production of man-made fibers in 1968 was 3,527,200 tons (about 48.4 percent of the total chemical fiber output). The first production of man-made fibers on an indus-trial scale was begun in France in 1891.