the fibers that cover the seeds of the cotton plant (Gossypium). When the plant matures, the fiber is harvested without removing the seeds; the harvested product is called seed cotton. During initial processing at gins, the seeds are separated to produce successively fibers mostly longer than 20 mm, fibers less than 20 mm long, and short fibers less than 5 mm long. The first category accounts for about one-third of the total mass of the seed cotton. Cotton is the most inexpensive and common type of textile fiber. It accounts for approximately 50 percent of the world production of textile fibers.
In Russian technical literature until the second half of the 19th century, the term khlopchataia bumaga (literally “cotton paper”) was used for cotton fiber instead of the current term khlopok. The adjectival derivative khlopchatobumazhnyi is still used, for example, in reference to the cotton industry and cotton fabric. In modern technical literature, the terms khlopok-volokno (“lint cotton”) and khlopok-syrets (“seed cotton”) are usually used instead of khlopok.
Cotton pressed into prism-shaped bales is delivered to spinning mills. In addition to fiber suitable for processing, the bale cotton contains various defective cotton fibers and contaminants, which reduce the quality of the cotton because they make the spinning process more difficult, decrease the output of yarn, and spoil the yarn’s appearance. The amount of waste material in cotton fiber depends primarily on the methods used for harvesting the seed cotton and for primary processing, but also on the cotton plant variety and the conditions of growth.
Cotton defects differ in degree of harmfulness and may be classified in three groups. First are fiber defects—tangles (packed and intertwined bundles of fibers) and flattened clusters of immature fibers. Such defects are broken into fiber by opening and carding machines during spinning. Most of the defective pieces are converted to yarn, and the rest become waste material. The second group of defects includes immature and crushed seeds and contaminants (parts of leaves, bolls, and branches of the cotton plant). During the spinning process they are separated into waste, which reduces the yarn output and makes the yarn more expensive. The third group includes the particularly undesirable defects—parts of seed husks with fibers and linters as well as very small clusters of tangled fibers. They are difficult to separate from the cotton, but they increase the thread breakage on the spinning machines and spoil the appearance of the articles produced.
Cotton is subdivided into two types, depending on the type of plant from which it is obtained and the most important qualitative characteristic, the fineness, or smallness of the cross section, of the fiber. The two classes are medium-fine and fine cotton; the latter has a longer and finer fiber. In the USSR fine cotton accounted for approximately 10 percent of the total production volume in 1976. It is produced from Soviet strains of fine-fiber cotton plants. All Soviet cottons are divided into seven grades, depending on breaking strength and degree of maturity: select (0), 1st, 2nd, 3rd, 4th, 5th, and 6th grades. In turn the cottons of grades 0 through 4 are subdivided into eight-types, depending on relative breaking strength and length. Cotton fiber of grades 5 and 6 is not subdivided into types.
Most cotton is processed for yarn; only a small portion of the cotton and linters is used to make medical garments, everyday apparel, furniture padding, and such products as packing and filters. Fibers shorter than 20 mm are also used in the chemical industry as a raw material from which synthetic fibers and yarns, films, lacquers, plastics, explosives, and other products are made.
Various textile products are made from cotton yarn, including fabrics, knitwear, nonwoven materials, sewing threads, twine, rope, and netting. Some textile goods are also produced from a blend of cotton with chemical and natural fibers.
A. N. SOLOV’EV