Rayon, cellulose acetate viscose

Cotton Cuprammonium Regular rayon viscose rayon High-tenacity viscose rayon Saponified acetate rayon Cellulose acetate (secon- dary) Cellulose tri- acetate... 

Natural polymers can be made into hbers through dissolution of the polymer in an appropriate solvent and then extmsion of the polymer solution into a coagulation bath. As an example, cellulose can be made into viscose rayon fibers, cuprammonium rayon, cellulose acetate and triacetate fibers, lyocell, and modal fibers depending on the processes used to make the fibers. Other natural polymers such as mbber, chitosan, alginic acid, and protein can also be made into fibers in an appropriate fiber-forming process. 

The cellulose molecule contains three hydroxyl groups which can react and leave the chain backbone intact. These alcohol groups can be esterified with acetic anhydride to form cellulose acetate. This polymer is spun into the fiber acetate rayon. Similarly, the alcohol groups in cellulose react with CS2 in the presence of strong base to produce cellulose xanthates. When extruded into fibers, this material is called viscose rayon, and when extruded into sheets, cellophane. In both the acetate and xanthate formation, some chain degradation also occurs, so the resulting polymer chains are shorter than those in the starting cellulose. 

Originally, the word rayon was appHed to any ceUulose-based man-made fiber, and therefore included the cellulose acetate fibers. However, the definition of rayon was clarified in 1951 and includes textiles fibers and filaments composed of regenerated cellulose and excludes acetate. In Europe the fibers are now generally known as viscose the term viscose rayon is used whenever confusion between the fiber and the cellulose xanthate solution (also called viscose) is possible. 

Phloroglucinol is Hsted in the Colourindex as Cl Developer 19. It is particularly valuable in the dyeing of acetate fiber but also has been used as a coupler for azoic colors in viscose, Odon, cotton (qv), rayon, or nylon fibers, or in union fabrics containing these fibers (157). For example, cellulose acetate fabric is treated with an aromatic amine such as (9-dianisidine or a disperse dye such as A-hydroxyphenylazo-2-naphthylamine and the amine diazotizes on the fiber the fabric is then rinsed, freed of excess nitrite, and the azo color is developed in a phloroglucinol bath at pH 5—7. Depending on the diazo precursor used, intense blue to jet-black shades can be obtained with excellent light-, bleach-, and mbfastness. 

Plastics and Other Synthetic Products. Sulfur is used in the production of a wide range of synthetics, including cellulose acetate, cellophane, rayon, viscose products, fibers, and textiles. These uses may account for 2% of sulfur demand in developed countries. Sulfur intermediates for these manufacturing processes are equally divided between carbon disulfide and sulfuric acid. 

This term was originally intended to denote all kinds of man-made textile fibres, but is now applied only to cellulose types. Viscose rayon (regenerated from a solution of cellulose xanthate in sodium hydroxide) accounts for the greater part of world rayon production. Acetate rayon and cuprammonium rayon are relatively unimportant. 

The graft copolymerization of acrylonitrile and of styrene onto regenerated celluloses, such as viscose rayon and cellophane, and onto cellulose acetate has been investigated by Pikler, Suta, and Alfoeldi (68) and by Alfoeldi and Pasteka (69). In both studies the authors used ozonized substrate for initiating the graft copolymerization. 

The natural fibers obtained from cotton, wood, flax, hemp, and jute all are cellulose fibers and serve as raw materials for the textile and paper industries. In addition to its use as a natural fiber and in those industries that depend on wood as a construction material, cellulose is used to make cellulose acetate (for making rayon acetate yarn, photographic film, and cellulose acetate butyrate plastics), nitric acid esters (gun cotton and celluloid7), and cellulose xanthate (for making viscose rayon fibers). The process by which viscose rayon is manufactured involves converting wood pulp or cotton Iinters into cellulose xanthate by reaction with carbon disulfide and sodium hydroxide ... 

Natural fibers such as cotton can be chemically modified to form rayon or acetate. Rayon was first called artificial silk. In the viscose process, cellulose is dissolved in sodium hydroxide, pushed through spinnerets, and treated with acid to harden. Treatment with copper compounds and ammonia is used to form hosiery yams. Acetate (or cellulose acetate), produced by treating cotton with acetic acid and acetic anhydride, is also used in production of clothing. 

Viscose rayon is but one variety of rayon, a more general term for derivatized or reconstituted cellulose. Other rayons include fiber prepared from collodion, cellulose acetate, and cellulose fiber regenerated from a cellulose-copper ammonium solution cuprammonium rayon) (Kauffman 1993). 

The first man-made fibers of commercial importance were the cellu-losics. With respect to regenerated cellulose fibers, viscose rayon predominates. Between 1900 and 1967, world production of viscose rayon rose from 1000 tons to 2,700,000 tons (3). Cellulose derivative fibers did not go into commercial production until the 1920s. At that time cellulose acetate was manufactured. Cellulose triacetate fiber was brought into commercial production in the United States in 1954 (4). 

Below the black thread at the top, the fibers are acetate rayon (cellulose di- or triacetate, SEF (Monsanto s modacylic), Amel (cellulose triacetate), cotton, Creslan (polyacrylonitrile). Dacron 54 and 64 (polyester without and with a brightener), nylon 6.6 (polyamide), Orion 75 (polyacrylonitrile), silk (polyamide), polypropylene, viscose rayon (regenerated cellulose), and wool (polyamide). 

Establishments primarily engaged in manufacturing cellulosic fibers (including cellulose acetate and regenerated cellulose such as rayon by the viscose or cuprammonium process) in the form of monofilament, yarn, staple, or tow suitable for further manufacturing on spindles, looms, knitting machines, or other textile processing equipment. 

Semi-syntbetic The raw ingredient for viscose (rayon) and acetate is cellulose, made from wood chips. Cellulose fibers are found in all plants, and make up the bulk of wood. The cellulose Is dissolved using chemical processes, then the mixture is squeezed through a spinneret, which has many small holes, to make fine filaments. 

FIGURE 2.37 Typical cross-section of fibers produced by different spinning processes (a) melt-spun nylon from various shaped orifices (b) dry-spun cellulose acetate from round orifice (c) wet-spun viscose rayon from round orifice. 

Fiber, rayon The generic term for fibers, staples, and continuous filament yarns composed of regenerated cellulose but also frequently used to describe fibers obtained from cellulose acetate or cellulose triacetate. Rayon fibers are similar in chemical structure to natural cellulose fibers (cotton) except that the synthetic fiber contains short plastic units. Most rayon is made using the viscose process. 

The name rayon was officially adopted in 1924 by the National Retail Dry Goods Association. Prior to this, the fiber was called artificial silk, wood-silk, or viscose silk. On October 26, 1937, the Federal Trade Commission (FTC) officially defined rayon as a textile fiber or yarn produced chemically from cellulose or with a cellulose base. This definition covered cuprammonium and viscose rayon as well as acetate fiber. To avoid confusion in the trade, FTC rules were adopted on December 11, 1951, which defined rayon as man-made textile fibers and filaments composed of regenerated cellulose. A separate definition was adopted for acetate, man-made textile fibers and filaments composed of cellulose acetate. ... 

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