Synthetic chemical fiber polyamide

Nylon. In 1939 the DuPont Company introduced the first truly synthetic textile fiber. Dr. Wallace Carothers invented nylon as a result of his basic research into polymer science. Chemically, nylon is a polyamide fiber. The two major types of nylon polymer are used in textiles type 6,6 which is made by using hexam-ethylene glycol and adipic acid, and type 6, which is made by polymerizing e-caprolactam. Nylon fibers are made by melt-spinning the molten polymer. The result is a continuous filament fiber of indeterminate length. It is spun in many deniers, with its diameter varying from 10 to 50 microns. The cross-section usually is round, trilobal, or square with hollow channels when used as carpet fiber. 

Fibers from synthetic polymers make up approximately 80% of the total production of chemical fibers in Germany and about 90% worldwide (2000). The most important synthetic fibers are polyamide (Wulfhorst, 1997), polyester (Tetzlafi", 1997), and polyacrylonitrile (Wulfhorst, 1998). Because of their very specific properties, polyvinyl chloride (Koch, 1968), polytetrafluoroethylene, polyolefin fibers (such as polyethylene and polypropylene) (Wulfhorst, 1989b), and polyvinyl alcohol are used mostly for technical textiles. At the end of this section, an overview is given of synthetic polymers featuring the chemical structures, specific properties, and various applications (Table 2.7). The physical characteristics of chemical fibers from synthetic polymers are summarized later in Table 2.8. 

By the end of the 19th century, important advances in the area of cellulose chemistry led to the development of chemical fibers from natural polymers. A first major step was the development of artificial silk made from nitrocellulose by Count Hilaire de Chardonnet and presented at the world exhibition in Paris in 1894. Alas, some unfortunate women wearing his new garments went up in flames when they accidentally came to close to open fire because nitrocellulose also makes an excellent explosive. Despite these initial difficulties, other inventions in the early 20th century in macromolecular chemistry, namely viscose production by Urban, Frem-ery, and Bronnert in 1901 and the discovery of macromolecules by H. Staudinger, initiated the development of chemical fibers from synthetic polymers, such as polyamide (PA), polyester (PES), polyacrylonitrile (PAN), and polyurethane (PUR). It took another 60 years until in 1993, the overall production of man-made fibers for the first time exceeded that of natural fibers. 

Synthetic Fiber and Plastics Industries. In the synthetic fibers and plastics industries, the substrate itself serves as the solvent, and the whitener is not appHed from solutions as in textiles. Table 6 Hsts the types of FWAs used in the synthetic fibers and plastic industries. In the case of synthetic fibers, such as polyamide and polyester produced by the melt-spinning process, FWAs can be added at the start or during the course of polymerization or polycondensation. However, FWAs can also be powdered onto the polymer chips prior to spinning. The above types of appHcation place severe thermal and chemical demands on FWAs. They must not interfere with the polymerization reaction and must remain stable under spinning conditions. 

Nylon is similar ia its general chemical stmcture to the natural fiber wool, and therefore all the previously described processes for wool are appHcable to dyeiag nylon with acid, metallised, and other dyes. There are, however, significant differences. Nylon is synthetic, it has defined chemical stmcture depending on the manufactufing process, and it is hydrophobic (see Fibers, POLYAMIDES). 

Fibers in which the basic chemical units have been formed by chemical synthesis, followed by fiber formation, are called synthetic fibers. Examples include nylon, carbon, boron fibers, organic fibers, ceramic fibers, and metallic fibers. Among all commercially available fibers, Kevlar fibers exhibit high strength and modulus. (Kevlar is a DuPont trademark for poly [p-phenylene diamine terephthalamide].) It is an aromatic polyamide (aramid) in which at least 85% of the... 

Polyamide fibers, 19 739-772. See also Synthetic polyamides applications for, 19 765-766 chemical properties of, 19 745-747 cross-section shape of, 19 756 dyeability of, 19 758-760 early reactive dyes for, 9 468-470 electrical properties of, 19 745 manufacture of, 19 748-749 modified nylon-6 and nylon-6,6, 19 760-764... 

One of the most important condensation polymers is nylon, a name so ingrained into our language that it has lost trademark status. It was developed by Wallace Carothers, director of organic chemicals research at DuPont, and was the outgrowth of his fundamental research into polymer chemistry. Introduced in 1938, it was the first totally synthetic fiber. The most common form of nylon is the polyamide formed by the condensation of hexamethylene diamine and adipic acid ... 

Chemical or synthetic fibers are further classified into regenerated and synthetic fibers. Regenerated or semisynthetic fibers are produced from natural products by a chemical procedure or modification. These fibers can, for example, be rayon, acetate silk, and alginate fibers. In contrast, synthetic fibers are completely synthesized from other raw materials, and may, for example, consist of polyesters, polyamides, poly(acrylonitrile), polyolefins, or glass. 

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