Synthetic chemical fiber polyacrylonitrile

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. 

Synonyms and trade names cyanoethylene, 2-propenenitrile, vinyl cyanide Use and exposure Acrylonitrile is a colorless, man-made liquid with a sharp, onion- or garlic-like odor. It can be dissolved in water and evaporates quickly. Acrylonitrile is used principally as a monomer in the manufacture of synthetic polymers, polyacrylonitriles, acrylic fibers, and other chemicals such as plastics and synthetic rubber. A mixture of acrylonitrile and carbon tetrachloride was used as a pesticide in the past. - Acrylonitrile is highly flammable and toxic. It undergoes explosive polymerization. The... 

In much the same way, natural polymeric fibers like wool, cotton, silk, etc., are often touted as superior to anything that is man-made or synthetic. But is this fair There is no doubt that natural fibers have a unique set of properties that have withstood the test of time (e.g., it is difficult, but not impossible, to match silk s feel or cotton s ability to breathe ). On the other hand, consider Lycra , a completely synthetic fiber produced by DuPont (Figure 1-12) that has a truly amazing set of properties and is the major component of Spandex (a material that keeps string bikinis on ). Or consider the wrinkle-free polyester fibers used in clothing and the stain proof nylon and polyacrylonitrile polymers used in carpets. The point here is that polymers, be they natural" or synthetic, are all macromolecules but with different chemical structures. The challenge is to design polymers that have specific properties that can benefit mankind. 

Manufactured protein fibers, often called azlons, are man-made fibers produced from animal or plant proteins. Examples of protein sources are milk, chicken feathers, soy beans, peanuts, corns, etc. Traditionally, most manufactured protein fibers were made directly from proteins dissolved in solvents. Recent trends in the research and development of manufactured protein fibers include the use of biochemistry to modify the source proteins and the introduction of synthetic polymers such as polyvinyl alcohol and polyacrylonitrile to improve the fiber mechanical properties. Antibacterial agents are often being added during the fiber formation process to provide health benefits to the manufactured protein fibers. As a result, the chemical structure of manufactured protein fibers is becoming more complex. 

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