Textile yarns and fibres

Yarns are the raw materials manipulated during knitting. A yarn is defined as ‘an assembly, of substantial length and relatively small cross-section, of fibres or filaments, with or without twist’. The term ‘thread’ is used for yarn and does not imply that it is as smooth, highly twisted and compact as a sewing thread. Yarn is a strand composed of fibres, filaments (individual fibres of extreme length), or other materials, either natural or man-made, suitable for use in the construction of interlaced fabrics, such as woven or knitted types. The strand may consists of a number of fibres twisted together; a number of filaments grouped together but not twisted; a number of filaments twisted together; a single filament, called a monofilament, either with or without twist; or one or more strips made by dividing a sheet of material, such as paper or metal foil, and either twisted or untwisted. The properties of the yarn employed greatly influence the appearance, texture, and performance of the completed fabric. Textile fibres are the raw materials of the yarns into which they are spun. There are two configurations of fibres: staple fibres and filament fibres.

Staple fibres are of comparatively short length – for example, cotton and wool fibres, which require spinning and twisting together in order to produce a satisfactory length of yarn of suitable strength.

A filament is a fibre of indefinite length – for example silk, which requires combining with other filaments, usually with some twist, in order to produce a yarn of sufficient bulk.

The first fibres available for textile use were obtained from plant and animal sources. Over a long period of experimentation with many natural fibers available, cotton, wool, jute, flax, and silk have become recognized as the most satisfactory. The commercial development of man-made fibres began late in the 19th century, experienced much growth during the 1940s, expanded rapidly after World War II, and in the 1970s was still the subject of extensive research and development. This group includes regenerated fibres, such as rayon, made from fibre-forming materials already existing in nature and manipulated into fibrous form, and synthetic fibres, with the fibre-forming substance produced from chemicals derived from such sources as coal and oil, and then made into such fibres as nylon and polyester.

Knitting requires a relatively fine, smooth, strong yarn with good elastic recovery properties. The worsted system has proved particularly suitable for spinning yarns used for knitwear, outerwear and socks, and the combed cotton system for underwear, sportswear and socks.

The introduction of synthetic fibres, which can be heat set in a permanent configuration, has led to the development of texturing processes that directly convert these filaments into bulked yarns.

The development of synthetic fibres and their texturing processes has proved particularly beneficial to the knitting industry. The most recent development is the widespread use of the elastane fibre- lycra to support the elastic properties of knitted garments. The period from the mid-1960s to 1973 is often regarded by knitters as a ‘golden age’ because fashionable demand for textiles composed of synthetic fibres reached a peak during that period.

Дата добавления: 2015-11-16