Spandex yarn increases the elongation of the stretch fabrics depending on the direction of the elasticity in the fabric and also enhances the crease recovery of the cotton and blend stretch fabrics, aver Yasser M E Hassan , Ahmed EL-Salmawy, and Alsaid A Almetwally.
Spandex (also known as elastane) is a manufactured fibre in which the fibre-forming substance is a long chain synthetic elastomer consisting of at least 85% by weight of segmented polyurethane. While many different soft-segmented chemistries for spandex have been evaluated over the years, only polyether and polyester chemistries remain in use today. Also for major commercial spinning processes (solution dry spinning, solution wet spinning, reaction spinning, and melt spinning) for spandex have been practiced over the last 30 years. The various processes yield fibres with distinctively different attributes including cross-sectional geometry and stress-strain properties
Today there are many spandex producers all over the world and several brands, types and costs of spandex in the market. The main types of spandex yarns that are used in weaving and knitting machines together with other yarns are bare, single-covered, double-covered, core-spun, and core plies yarns. Each form of spandex properly used, provides for a high elasticity in fabric.
Various previous studied have reported the physical and chemical properties of spandex fibres. An elastic fibre has been characterised by high breaking elongation (exceeding 100% and generally 50 to 800%), a low modulus of elasticity (approximately 1/1000 that of a conventional "Hard” fibre, such as nylon, cotton, and so on) and both a high degree and a high rate of recovery from 100% stretching (about 95%). Spandex fibres are resistant to hydrolysis (Lycra had power retention of 100% after boiling for 1 hour in water at pH 3 to 11). In addition the spandex fibres have good resistance to ultraviolet radiation, oxygen, heat, and oil.
Fabrics containing spandex yarn have a wide application value, especially because of their increased extensibility, elasticity, high degree of recovery, good dimensional stability, and simple care[11,12,13]. In apparel industry, these kinds of fabrics are used for sport cloths, and leisure cloths, hosiery, underwear and swimwear, so therefore for body-confirming garment which ensure stable shape under loading during wearing.
The objective of this study was to investigate the performance of randomly selected woven fabrics from the market, which containing spandex. Fabric breaking load in two directions, ie, warp and weft direction, and crease resistance were considered the most important properties that must be found in spandex fabrics. Fabric breaking load and elongation versus the drawing ratio will also be investigated.