Spandex is a kind of elastic fiber made of polymer compound with linear segment structure containing more than 85% polyurethane. Due to the advantages that other fibers cannot match, such as light specific gravity, high breaking strength, high breaking elongation, good elastic recovery, etc., spandex fiber has been widely used in various fields. Different yarn forms such as covered yarn are used in warp knitting, weaving, knitting and other processing methods to make swimsuits, underwear, outerwear and other clothing. In recent years, they have become special textile fibers that are indispensable for the development of elastic textiles. It has a wide range of application value and development prospects. The main physical and chemical properties of spandex

1. Morphology The cross-section of polyester elastic fiber is broad bean-like, and the cross-section of polyether elastic fiber is triangular.

2. Strong elongation and elasticity Spandex has very low strength, the breaking strength of its filament is about 4-9cN/tex, but the elongation of spandex is very large, the elongation at break is 450%-800%, and the elasticity is very good. Therefore, high elongation and high elasticity are the major characteristics of spandex.

3. Hygroscopicity and dyeability Spandex has poor hygroscopicity, and the moisture regain is about 0.8% to 1% under general atmospheric conditions. But its dyeing performance is better.

4. Other properties The density of spandex is better, only 1-1.3g/cm3.

In addition, spandex has better acid and alkali resistance, solvent resistance, light resistance, and abrasion resistance.