Elastic fiber is an essential material in our lives. Without it, there would be no women’s stockings, no summer swimsuits, no figure-highlighting tights… It can be said that elastic fiber has made an indelible contribution to human beings showing their figures and enjoying the comfort of dressing.
The elastic fiber we often see in the content of clothes is “spandex”. Although the content is not high, it is very important. Here, the editor will share with you a shopping tip:
When shopping online, check the ingredient label of the clothes. You can get a rough idea when you see the spandex. Know that this piece of clothing has a slimming effect and can be worn slightly tight. For clothes without elastic fiber, you generally need to choose looser clothes and not be too close-fitting, otherwise it will hinder normal activities. Isn’t it useful?
According to the definition given by the American Society for Testing and Materials ASTM: elastic fiber filaments are stretched repeatedly at room temperature. A type of fiber that is at least twice its original length and can quickly return to its original length after the tension is released. The following six types of fibers can all be called elastic fibers.
Diene elastic fiber (rubber yarn)
Diene elastic fiber is commonly known as rubber yarn or elastic yarn, and its elongation rate is generally between 100% and 300%. The main chemical component is vulcanized polyisoprene, which has good chemical and physical properties such as high temperature resistance, acid and alkali resistance, and wear resistance. It is widely used in knitting industries such as socks and ribbed cuffs.
Rubber yarn is an elastic fiber used in the early days. Because it is mainly made into thick yarn, it is used in woven fabrics. The scope of use is very limited.
Polyurethane fiber (spandex)
Polyurethane elastic fiber refers to a fiber made of a block copolymer with polyurethane as the main component. In my country, it is called spandex. The original trade name in the United States was Spandex, which was later renamed. It is Lycra, Elastane in Europe, Neolon in Japan, and Dorlastan in Germany.
Its elasticity comes from its molecular structure consisting of a block copolymer network composed of “soft” and “hard” segments structure. This kind of fiber has different block copolymers and different spinning processes. After forming different “segment” network structures, the elasticity and dyeing and finishing processing properties are also different.
Polyetherester elastic fiber
Polyetherester elastic fiber is an elastic fiber produced by melt spinning of polyester and polyether copolymer. Teijin Company of Japan
First produced in 1990. Polyetherester elastic fiber not only has high strength, but also has good elasticity.
At 50%, the elasticity of medium-strength elastic fiber is equivalent to spandex, and the melting point is also higher. When blended with PET fiber, it can be used at 120℃~130℃
It is dyed at ℃, so polyester fiber can also be processed into elastic textiles. In addition, they have excellent light resistance, chlorine bleaching resistance, acid and alkali resistance, etc. are better than ordinary spandex. Due to its good acid and alkali resistance, the fabric composed of it and polyester can also be processed with alkali reduction to improve the drape of the fabric.
This fiber also has the advantages of cheap raw materials, easy production and processing, and is a promising fiber.
Polyolefin elastic fiber
Polyolefin elastic fiber is produced from polyolefin thermoplastic elastomer through melt spinning. Dow Chemical (DOW
XLA, launched by Chemical in 2002, is the first commercialized polyolefin elastic fiber. It is produced by melt spinning of ethylene-octene copolymer (POE) catalyzed by metallocene catalyst in situ polymerization. It has good elasticity, 500% elongation at break, can withstand high temperatures of 220°C, is resistant to chlorine bleaching and strong acid and alkali treatment, and has strong resistance to ultraviolet degradation. Its production process is relatively simple, its raw material price is lower than that of spandex, and it produces almost no pollution during the production process and is easy to recycle.
Because polyolefin elastic fibers have a variety of excellent properties, their applications have become increasingly widespread in recent years.
Composite elastic fiber
CONTEX
Kantex (ST 100 composite elastic fiber, collectively known as T400 in the market
Elastic fiber) is a new two-component composite elastic fiber made of DuPont Sorona as the main raw material and ordinary PET through advanced composite spinning technology; it has natural permanent spiral curl and excellent bulk, elasticity and elastic recovery rate , color fastness and particularly soft feel. It can be woven alone or interwoven with cotton, viscose, polyester, nylon, etc. to form a variety of styles.
It not only solves the problem of traditional spandex yarn being difficult to dye and having excessive elasticity, the weaving is complex, the fabric size is unstable, and it is easy to age during use. It can be woven directly on air-jet, water-jet, and arrow looms. It does not have to be made into covered yarn before it can be used on the machine like spandex. Weaving reduces yarn costs and improves product quality uniformity.
Hard elastic fiber
The above-mentioned elastic fibers are all soft elastic fibers, which undergo greater deformation and recovery under lower stress. From a thermodynamic perspective, elasticity comes from the degree of freedom (or disorder) of the molecular chain, that is, the change in the entropy value of the system. Therefore, the crystallinity of the above-mentioned fibers is very low. However, some fibers made under special processing conditions, such as polypropylene (PP), polyethylene (PE) and other fibers, although not easy to deform under low stress (because they have a higher modulus), are not easily deformed under high stress. It also has good elasticity under stress, especially at lower temperatures, so this type of fiber is called hard elastic fiber.
The deformation and recovery of hard elastic fibers are significantly different from those of elastic fibers. For example, hard elasticity
PP
If the fiber is stretched for the second time immediately after being stretched and recovered, its modulus and strength will drop a lot. However, if the fiber is left for a period of time after the stress is removed, or the temperature is raised to fully relax it and then stretched for the second time, its modulus and strength will drop a lot. The deformation recovery is basically close to the first curve. This is because when the hard elastic fiber is stretched and restored, not only the stretching and retraction deformation of the long chain segments of the crimped molecules of the soft elastic fiber occur, but also some changes in the micropore structure are accompanied during the stretching process. The chip network structure has also changed. Only after these structural changes gradually recover can they return to their original state. Therefore, they deform and recover under higher pressure and are called hard elastic fibers.
At present, hard elastic fibers are not widely used in textiles, but because their elastic characteristics are different from soft elastic fibers, they can be developed Some special textiles.
