Do You Think Spandex Is The Only Elastic Fiber? These Fibers Also "Bounce" Infinite Force Oh!

Elastic fiber has made an indelible contribution to show human figure and enjoy the comfort of dressing. Girls' sexy stockings, bikini in summer and beautiful and slim tights in winter are inseparable from her.
Spandex is a common elastic fiber, which can increase the comfort and flexibility of people's activities. However, if you think spandex is the only elastic fiber, you are wrong. According to the definition of American Society for testing and materials (ASTM), elastic fiber refers to a kind of fiber whose material is repeatedly stretched to at least twice its original length at room temperature, and can quickly recover to its original length after the tension is released. Therefore, the following six kinds of fibers can be called elastic fibers.

1. Diene elastic fiber (rubber wire)

Diene elastic fiber, commonly known as rubber or rubber fiber, has an elongation of 100% - 300%. The main chemical component is sulfurized polyisoprene, which has good chemical and physical properties such as high temperature resistance, acid and alkali resistance and wear resistance, which is widely used in knitting industry such as socks and rib cuffs. Rubber filament is an early used elastic fiber, because it is mainly made into coarse yarn, so its use in weaving fabric is very limited.
2. Polyether ester elastic fiber

Polyether ester elastic fiber is a kind of elastic fiber made from polyester and polyether copolymer by melt spinning. It was first produced by Japan's Tei Ren company in 1990. Polyether ester elastic fiber not only has high strength, but also has good elasticity. At 50% elongation, the elasticity of medium strength elastic fiber is equivalent to that of spandex, and its melting point is also high. When blended with PET fiber, it can be dyed at 120 ℃ ~ 130 ℃. Therefore, polyester fiber can also be processed into elastic textiles. In addition, their light resistance, chlorine resistance, acid and alkali resistance are better than ordinary spandex. Due to its good acid and alkali resistance, the fabric composed of polyester and it can also be reduced in order to improve the drapability of the fabric. This kind of fiber also has the advantages of cheap raw materials, easy production and processing, and is a kind of fiber with a bright future.
3. Polyolefin elastic fiber
Polyolefin elastic fiber is prepared by melt spinning of polyolefin thermoplastic elastomer. XLA, introduced by Dow Chemical in 2002, is the first commercial polyolefin elastic fiber. It is prepared by melt spinning ethylene octene copolymer (POE) in situ polymerization catalyzed by metallocene catalyst. It has good elasticity, 500% elongation at break, resistance to high temperature of 220 ℃, chlorine bleaching and strong acid and alkali treatment, and has strong anti ultraviolet degradation performance. Its production process is simple, the price of raw materials is lower than that of spandex, at the same time, the production process hardly produces pollution and is easy to be recycled. Polyolefin elastic fibers have been widely used in recent years due to their excellent properties.
4. Composite elastic fiber
Contex contex (st 100 composite elastic fiber, collectively referred to as T400 elastic fiber in the market) is a new two-component composite elastic fiber made of DuPont Sorona and ordinary pet through advanced composite spinning process. It has natural permanent spiral curl, excellent bulkiness, elasticity, elastic recovery, color fastness and soft handle, It can not only be pure woven alone, but also interwoven with cotton, viscose, polyester, nylon, etc., forming a variety of styles.
It not only solves the problems of traditional spandex yarn, such as difficult dyeing, excessive elasticity, complex weaving, unstable fabric size, and easy aging in the process of use, but also can be directly woven on air-jet, water jet and arrow bar looms. It does not need to be made into coated yarn before weaving, which reduces the cost of yarn and improves the quality uniformity of products.
5. Hard elastic fiber
The elastic fibers mentioned above are all soft elastic fibers, which have large deformation and recovery under low stress. From the thermodynamic point of view, the elasticity comes from the degree of freedom (or chaos) of the molecular chain, that is, the change of entropy value of the system, so the crystallinity of the above fibers is very low. However, some fibers, such as polypropylene (PP) and polyethylene (PE), made under special processing conditions, are not easy to deform under low stress (because they have higher modulus), but they also have better elasticity under higher stress, especially at lower temperature. Therefore, these fibers are called hard elastic fibers.
The deformation and recovery of hard elastic fiber are obviously different from that of elastic fiber. For example, the modulus and strength of hard elastic PP fiber will decrease a lot if it is stretched for the second time immediately after tensile recovery. However, if the stress is removed and placed for a period of time, or the temperature is raised to make it fully relaxed, the deformation recovery is close to the first bending base. This is because when the hard elastic fiber is stretched and recovered, not only the stretching and retracting deformation of the long chain segment of the soft elastic fiber curling molecule occurs, but also some changes of the micropore structure and the wafer network structure are also occurred during the stretching process. Only when these structural changes gradually recover can they return to the original state, so they can deform and recover under high pressure, which is called hard elastic fiber.
At present, hard elastic fiber is not widely used in textiles, but because its elastic characteristics are different from that of soft elastic fiber, some special textiles can be developed.