Chemical fibers from synthetic polymers

In contrast to chemical fibers from natural polymers (Section 2.2.2), whose chain molecules already exist in nature, the chain molecules of chemical fibers from synthetic polymers are produced artificially by synthesis of monomers (Koch, 1970). 

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. 

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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. 

Structural models are useful to illustrate the properties and the processes taking place during the production of chemical fibers. Chemical fibers from natural and synthetic polymers can be described very well with a two-phase model a fiber is composed of rather random (amorphous) and ordered (crystalline) regions. The properties of a fiber result from the combination of these two phases. This experimentally supported model (Fig. 2.23) is described below. 

Chemical fibers are produced from modified natural or synthetic high molecular substances and are classified as artificial ones obtained by chemical processing of natural raw material, commonly cellulose (viscose, acetate), and synthetic ones obtained from synthetic polymers (nylon-6, polyester, aciyl, PVC fibers, etc.). 

This chapter discusses synthetic polymers based primarily on monomers produced from petroleum chemicals. The first section covers the synthesis of thermoplastics and engineering resins. The second part reviews thermosetting plastics and their uses. The third part discusses the chemistry of synthetic rubbers, including a brief review on thermoplastic elastomers, which are generally not used for tire production but to make other rubber products. The last section addresses synthetic fibers. 

Despite present trends toward use of synthetic polymers developed over the last 10 or 20 years, starches are still being widely used as an adhesive in such applications as the production of paper and paperboard products, warp sizing, and bonding charcoal briquettes. Because of a unique combination of properties and low cost, these adhesives are almost impossible to exclude from many applications, especially those involving the use of hot paste (size) for anchoring fibers. For starch molecules to act as an adhesive, they must be chemically or thermally hydrated. Then, their adhesive character is developed and modified in different ways by chemicals or other additives for different end uses. As renewable resources that are both economical and reliable, starch and dextrin are likely to continue to be significant factors in the adhesive market for many years. 

The solid particles in PF dispersions are not of simple shapes (e.g., spheres, rods) and they are deformable, and have multimodal size distributions (Tanglertpaibul and Rao, 1987a). Also, the particles are hydrated and are in physical and chemical equilibrium with the continuous medium so that they differ significantly from artificial fibers such as of glass or of synthetic polymers. The continuous phases of PF dispersions also have features that are different than those of non-food suspensions. The continuous medium of a typical food dispersion, usually called serum, is an aqueous... 

Before the development of synthetic polymers, people were limited to using natural substances such as stone, wood, metals, wool, and cotton. By the turn of the twentieth century, a few chemically treated natural polymers such as rubber and the first plastic, celluloid, had become available. Celluloid is made by treating cellulose from cotton or wood fiber with nitric acid. 

The solid-state NMR method described in this article is still useful in the determination of the local structure in oriented synthetic polymers as well as protein fibers. In this section, bond orientation will be treated first, as a more simple stage in the structural determination on the basis of chemical shielding. Namely, the NH bond orientation relative to the oriented axis can be calculated from the N chemical shielding when the oriented axis is set parallel... 

Polymer forming began with the chemical modification of natural polymers such as natural rubber vulcanization and cellulose acetylation. The first efforts to shape natural polymers and early synthetic ones into useful products such as textile fibers and films for packaging date from the middle of the 19 century. 

Polyvinyl chloride is a synthetic polymer that was first described by Regnault in 1838 [142]. Although there was already a German patent in 1913, which suggested the formation of new fiber from PVC [143], the chemical industry did not begin to show an active interest in this polymer until the early 1930s. 

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