CELLULOSE ACETATE

original name Acetate Rayon, also called Acetate, man-made textile fibre produced from the plant substance cellulose, which is obtained from soft woods or the short fibres adhering to cotton seeds (linters) and treated with acetic acid and acetic anhydride, and then partially hydrolyzed so that the product, secondary acetate, is soluble in acetone. It forms a cellulose acetate solution that is extruded through fine holes in a nozzle called a spinneret, forming a fibre. Unlike rayon (q.v.) it is not converted back to pure cellulose but remains as cellulose acetate. During the manufacturing process, the fibre is slightly stretched, increasing its strength. Cellulose acetate does not have the same affinity for dyestuffs as rayon and was not generally accepted until suitable dyes were developed. It is sometimes coloured by incorporating pigment in the spinning solution. Acetate is produced in the form of a long filament but is frequently cut into short lengths, or staple fibres, sometimes with crimp (waviness) imparted, to be spun into yarn. Acetate, normally glossy, can be dulled by the addition of appropriate pigments. The fibre is much weaker than nylon or even nylon staple and is also low in elasticity. The fibre can absorb about 6.5 percent of its weight in moisture. Heating produces softening, and melting occurs at about 232 C (450 F). Acetate will burn but is not easily ignited. Aging and exposure to sunlight slightly decrease strength but do not affect colour. Acetate achieved importance as a textile fibre in the 1920s and is valued for its attractive hand (properties perceived by handling) and good draping properties. It does not wrinkle easily when worn and, because of its low moisture absorption, does not easily retain certain types of stains. Acetate garments launder well, retaining their original size and shape and drying in a short time but have a tendency to retain creases imparted when wet. The fibre is used, alone or in blends, in such apparel as dresses, sportswear, underwear, shirts, and ties and also in carpets and other home furnishings. Because of its good insulation properties, acetate is used as a covering for wire in the electrical industry. Cellulose triacetate, generally known in the United States by the trade name Arnel, is chemically different from, but related to, secondary acetate, being fully acetylated cellulose. It has greater heat resistance than normal acetate, is faster-drying, and can be permanently pleated by heat setting. It is used, alone or in blends, for knitted and woven fabrics that are especially popular for women's apparel.