What are the main varieties of special fibers?

①　Corrosion-resistant fiber: It is a fluorine-containing fiber made of tetrafluoroethylene polymerization in the United States in 1954. It was successfully trial-produced in the United States. The trade name is Teflon (Teflon), which is called fluorine fiber in China. Polytetrafluoroethylene has a melting point of 327℃ and is difficult to dissolve. It has good chemical stability. It will not decompose when boiled in aqua regia, acid and concentrated lye. It is almost insoluble except for highly fluorinated reagents at high temperatures. Any solvent. Fluorine fiber fabrics are mainly used as industrial fillers and filter cloths.

②　High temperature resistant fiber: there are poly(metaphenylene isophthalamide) fiber, polyimide fiber, etc., which have high melting point and softening point, and can maintain good performance at a temperature above 200 ℃ for long-term use.

③　High-strength and high-modulus fiber: refers to a synthetic fiber with a strength greater than 10 g/denier and a modulus greater than 200 g/denier. For example, Kevlar, developed by the United States in 1968, is a fiber made from polyparaphenylene terephthalamide into a liquid crystal solution and spun through a dry-wet method. It is called Aramid 1414 in China and can be used as an airplane. Reinforcement materials for tire cord and aerospace and aviation equipment. Using viscose fiber, acrylic fiber and pitch as raw materials, high-strength, high-modulus carbon fiber can be obtained by high-temperature carbonization and graphitization. Composite materials made of carbon fiber are structural materials for the manufacture of spacecraft, rockets, missiles, and airplanes. They are also widely used in industrial sectors such as atomic energy, metallurgy, chemical engineering, and sports equipment.

④　Flame-resistant fiber: such as phenolic fiber, PTO fiber, etc., are non-flammable in flames, and can be used as fire-resistant and heat-resistant cord fabrics, thermal insulation materials and filter materials.

⑤　Elastomer fiber: The elongation at break is more than 400%, and the original length can be quickly restored after the external tensile force is removed. The representative variety of elastic fiber is polyurethane fiber, which is called spandex in China. Elastic fibers are made of block copolymers of hard and soft segments. The soft segment imparts high elongation to the fiber, and the hard segment does not deform and prevents relative slippage between molecules, thus imparting high resilience to the fiber. Elastic fibers can be used to make tights, swimming suits, elastic bands, socks, surgical socks, etc.

⑥　Functional fiber: Change the shape and structure of the fiber to make it have a certain special function. For example, the cuproammonium fiber or polyacrylonitrile fiber is made into a hollow form, which can be used as a material for artificial kidney hemodialysis in medical treatment. Polyamide 66 hollow fiber is used as a dialyzer for seawater desalination, and polyester hollow fiber is used as reverse osmosis equipment for concentration, purification and separation of various gases.