How many of the six commonly used Elastic fiber do you know?

Elastic fibers refer to strands with high extensibility and high resilience. The most classic definition is given by ASTM: "At room temperature, the material is repeatedly stretched to at least 2 times its original length, and after the tension is released, it can quickly recover to the original length" of a class of fibers, and for polyurethane materials, it means that after stretching to 3 times the original length, the release of tension can quickly recover the original length of the fiber. In addition, there are other definitions depending on the country and region.

Among the many functional varieties, elastic fiber as a "sunrise industry" can give the human body a good sense of contact, in the clothing wearing comfort, fluffy and warm plays an irreplaceable role, so in China and the world textile industry occupies a solid position, and give textile fabrics a certain elasticity has become an inevitable development trend of textiles.

Monodiene elastic fiber (rubber filament)

Diene elastic fibers are commonly known as rubber or rubber wire, and the elongation is generally between 100% and 300%. The main chemical component is sulfide polyisoprene, which has good chemical and physical properties such as high temperature resistance, acid and alkali resistance, wear resistance, etc., and is widely used in the knitting industry such as socks and ribbed cuffs. Rubber silk is an early used elastic fiber, because it is mainly made into thick yarn, so the use of fabric is very limited.

2. Polyurethane fiber (Spandex)

Polyurethane elastic fiber refers to a block copolymer made of polyurethane as the main component of the fiber, China is referred to as Spandex, the original product name in the United States, later renamed Lycra, the European name Elastane, Japan named Neolon, Germany named Dorlastan. Its elasticity comes from its molecular structure of a block copolymer network of so-called "soft" and "hard" segments. With the different block copolymers, the spinning process is different, and the elasticity and dyeing and finishing properties of the fibers are also different after forming different "segment" network structures.

The spinning methods of spandex include dry spinning, wet spinning, chemical reaction spinning and melt spinning. Dry spinning technology is the most common method for spandex industrial production at present, with the advantages of fast spinning speed (1000 m/min), small spinning size, good product quality, and small production workshop area, but at the same time there are serious environmental pollution and high cost disadvantages. On the contrary, melt spinning technology, without the use of solvents, coagulants, no waste water treatment problems, low production cost, has great development potential, is one of the hot spots of current research.

Spandex is the earliest developed and most widely used elastic fiber, the production technology is the most mature variety.

Third, polyether ester elastic fiber

Polyether ester elastic fiber is an elastic fiber made from polyester and polyether copolymer by melt spinning, which was first produced by Teijin Company in 1990. Polyether ester elastic fiber is similar to polyurethane elastic fiber in structure, and also has "segment" structure. The "soft" chain segment is mainly polyether chain segment, which has good softness, long chain and easy to stretch and deform; The "hard" chain segment is a polyester chain segment, which is relatively stiff, easy to crystallize, and the chain is short, which acts as a node when the fiber is stressed and deformed, giving the elastic recovery performance and determining the strength and heat resistance of the fiber.

Polyether ester elastic fiber is not only high strength, elasticity is also very good, at 50% elongation, the elasticity of medium strength elastic fiber has been comparable to spandex, the melting point is also high, and PET fiber blend, can be dyed at 120~130 ° C, so polyester fiber can also be processed into elastic textiles. In addition, their light resistance is excellent, chlorine bleaching resistance, acid and alkali resistance are better than ordinary spandex. Because of 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 kind of fiber also has the advantages of cheap raw materials, easy production and processing, and is a promising type of fiber.

Four, polyolefin elastic fiber (DOW XLA fiber)

Polyolefin elastic fibers are prepared from polyene thermoplastic elastomers by melt spinning. XLA, launched by DOW Chemical in 2002, is the first commercial polyolefin elastic fiber produced by melt spinning of in situ polymerized ethylene-octene copolymer (POE) catalyzed by a metallocene catalyst. It has good elasticity, 500% fracture elongation, resistance to 220℃ high temperature, chlorine bleaching and strong acid and alkali treatment, and has a strong resistance to ultraviolet degradation. Its production process is relatively simple, the raw material price is lower than spandex, and the production process almost does not produce pollution and is easy to recycle.

Polyolefin elastic fibers have been widely used in recent years because of their excellent properties.

Five, composite elastic fiber (T400 fiber)

CONTEX (ST 100 composite elastic fiber, collectively known as T400 elastic fiber in the market) is a new two-component composite elastic fiber made of DuPont Sorona as the main raw material and common PET through advanced composite spinning process. With natural permanent spiral curling and excellent bulk, elasticity, elastic recovery rate, color fastness and special soft feel, it can be pure woven alone, or interwoven with cotton, viscose fiber, polyester, nylon, etc., to form a variety of types of styles. It not only solves the traditional spandex silk is not easy to dye, excess elasticity, complex weaving, fabric size instability, and easy aging in the process of use and many other problems, and can be woven directly on the jet, water jet, arrow loom, do not have to be made into a covered yarn before weaving like spandex, reducing the cost of yarn, improve the quality of the product uniformity.

Six, hard elastic fiber

The above elastic fibers are soft elastic fibers, which have large deformation and recovery under low stress. From a thermodynamic point of view, elasticity comes from the degree of freedom (or disorder) of the molecular chain, that is, the change in the entropy of the system, so the crystallinity of the above fibers is very low. However, some fibers made under special processing conditions, such as polypropylene (PP), polyethylene (PE) and other fibers, although they are not easy to deform under low stress (because they have a higher modulus), but under higher stress, especially at lower temperatures, they also have better elasticity, so these fibers are called hard elastic fibers.

The deformation and recovery of hard elastic fibers are obviously different from those of elastic fibers. For example, the hard elastic PP fiber is immediately stretched for a second time after stretching recovery, and its modulus and strength are reduced a lot, but if it is placed for a period of time after removing the stress, or if the temperature is raised to make it fully relaxed for a second 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 shrinking deformation of the long chain segments of the above-mentioned soft elastic fiber cringing molecules occur, but also some changes in the micropore structure and the structure of their wafer network also change during the stretching process. Only after these structural changes gradually recover, can they return to the original state, so they deformation recovery under higher pressure, called hard elastic fibers.

At present, hard elastic fibers are not used much in textiles, but because their elastic characteristics are different from soft elastic fibers, some special textiles can be developed.