Elastane 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 clothes. When you see spandex, you can roughly understand that the clothes have a slimming effect and can be worn slightly tight. For clothes without elastic fiber, you should generally choose looser ones and not too tight. It should fit snugly, otherwise it will hinder normal activities. Isn’t it very practical?
However, if you think spandex is the only elastic fiber, you are totally wrong. We textile people work tirelessly to develop new fibers and new technologies, striving to contribute more to the clothing industry of mankind.
According to the definition given by the American Society for Testing and Materials ASTM: elastic fibers are fibers that are repeatedly stretched at room temperature to at least 2 times their original length, and that can quickly return to their original length after the tension is released. The following 6 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 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 knitted fabric industries such as socks and ribbed cuffs.
Rubber yarn is an elastic fiber used in the early days. Since it is mainly made into coarse-count yarn, its use in weaving fabrics 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 Lycra, Elastane in Europe, and Elastane in Japan. The name is Neolon, and the German name is Dorlastan.
Its elasticity comes from the block copolymer network structure of its molecular structure composed of "soft" and "hard" segments. 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. It was first produced by Teijin Company in Japan in 1990. Polyetherester elastic fiber not only has high strength, but also has good elasticity. When elongated by 50%, the elasticity of medium-strength elastic fiber is equivalent to that of spandex, and the melting point is also higher. When blended with PET fiber, chemical fiber fabric can be used at 120℃~ Colored at 130°C, polyester fibers 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 fiber 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. XLA, launched by DOW Chemical in the United States in 2002, is a commercialized polyolefin elastic fiber produced by melt spinning of ethylene-octene copolymer (POE) catalyzed in situ polymerization by metallocene catalysts. 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 easier, the 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.
Fitted elastic fiber
CONTEX (ST 100 laminated elastic fiber, collectively referred to as T400 elastic fiber in the market) is a new two-component laminated elastic fiber made from DuPont Sorona as the main raw material and ordinary PET through advanced laminated spinning technology; it has Natural permanent spiral crimp and excellent bulk, elasticity, elastic recovery rate, dyeing fastness and particularly soft feel. It can be woven alone or interlaced with cotton, viscose, polyester fiber, nylon, etc. , forming a variety of styles.
It not only solves many problems of traditional spandex yarns such as difficulty in coloring, excessive elasticity, complicated weaving, unstable fabric size, and easy aging during use, but also can be woven directly on air-jet, water-jet, and arrow looms without having to use the Like spandex, it must first be made into covered yarn before being woven on the machine, which reduces the cost of spinning yarn and improves the quality uniformity of the product.
Hard spandex
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 elastic PP fiber is stretched for the second time immediately after being stretched and recovered, and its modulus and strength will drop a lot. However, if the stress is removed and left for a period of time, or the temperature is raised to fully relax it, it is stretched for the second time. Stretching, the deformation recovery and the curve are basically close to each other. This is because when the hard elastic fiber is stretched and restored, not only the stretching and shrinking deformation of the long chain segments of the crimped molecules of the soft elastic fiber occur, but also some changes in the microporous structure are accompanied during the stretching process. The chip network structure has also changed. Only after these structural changes are gradually restored 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, some special textiles can be developed.
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