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”. However, if you thought spandex was the only thing available, you’d be wrong. We textile people work tirelessly to develop new fibers and new technologies, striving to contribute more to the clothing industry of mankind… (It seems that we are far away again~~ come back soon)
Follow U.S. The definition given by ASTM, the Society for Experimental Materials: Elastic fiber filaments are a type of fiber that is repeatedly stretched at room temperature to at least 2 times its original length, and can quickly return to its original length after the tension is released. The following 6 All fibers can be called elastic fibers.
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 resistance to With chemical and physical properties such as high temperature, acid and alkali resistance, and wear resistance, it is widely used in socks, ribbed cuffs and other knitting industries.
Rubber yarn is an elastic fiber used in the early days. Since it is mainly made into thick yarn, it is used in woven fabrics. The scope of use is very limited.
Polyurethane elastic fiber refers to a fiber made of a block copolymer with polyurethane as the main component. In China, it is called spandex. The original trade name in the United States was Spandex, which was later renamed Lycra and Elastane in Europe. , Japan’s name is Neolon, and Germany’s name is Dorlastan.
Its elasticity comes from its molecular structure, a block copolymer network 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 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 stretched 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, it can be used at 120℃~130℃ Polyester fibers can also be processed into elastic textiles due to the dyeing process. 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.
It not only solves many problems of traditional spandex yarn, such as difficulty in dyeing, 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. It does not need to be used like spandex. In this way, the covered yarn must be made first before it can be woven on the machine, which reduces the cost of the yarn and improves the quality uniformity of the product.
The above-mentioned elastic fibers are all soft elastic fibers, which undergo large deformation and recovery under low 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, if the hard elastic PP fiber is stretched for a second time immediately after recovery, 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, the fiber is stretched a second time. Stretch, the deformation recovery is basically close to the first curve. This is because when the hard elastic fiber is stretched and recovered, not only the stretching and retracting 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, some special textiles can be developed.
AAANHJJGHSFWfont-size: 16px; line-height: 25.6000003814697px; text-align: justify; box-sizing: border-box !important; word-wrap: break-word !important; background-color: rgb(255, 255, 255 );”>The deformation and recovery of hard elastic fibers are significantly different from those of elastic fibers. For example, hard elastic PP fibers are stretched a second time immediately after being stretched and recovered, and their modulus and strength will drop a lot, but if the stress is removed After leaving it for a period of time, or raising the temperature to fully relax it and then stretching it for the second time, its deformation recovery will be basically close to the first curve. This is because when the hard elastic fiber is stretched and recovered, not only the aforementioned soft The stretching and retracting deformation of the long chain segments of the crimped molecules of elastic fibers is accompanied by some changes in the micropore structure during the stretching process, and their wafer network structure also changes. Only after these structural changes are gradually restored, can Return to the original state, so they deform and recover under higher pressure, which is called hard elastic fiber.
At present, hard elastic fibers are not widely used in textiles, but due to Its elastic characteristics are different from soft elastic fibers, so some special textiles can be developed.
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