Rayon fibers, from cellulose xanthate

In 1664, Robert Hooke, predicted that silk could be produced by artificial means but man-made cellulosic fibers were not produced until Count Chardonnet used the cuprammonia process to produce rayon in 1891. Viscose rayon was produced in the UoS. from cellulose xanthate in 1910 and is still in production. ... 

Viscose Also known as the Cross-Bevan-Beadle process. A process for making regenerated cellulose fibers. The product has been known by the generic name rayon since 1924. Cellulose, from cotton or wood, is first reacted with sodium hydroxide ( mercerization), yielding alkali cellulose. This is dissolved in carbon disulfide, yielding cellulose xanthate, which is dissolved in sodium hydroxide solution. Injection of this solution (known as viscose... 

Cellulose is sometimes used in its original or native form as fibers for textile and paper, but is often modified through dissolving and reprecipitation or through chemical reaction. The xanthate viscose process, which is used for the production of rayon and cellophane, is the most widely used regeneration process. The cellulose obtained by the removal of lignin from wood pulp is converted to alkali cellulose. The addition of carbon disulfide to the latter produces cellulose xanthate. 

Regenerated proteins from casein (lanital), peanuts (ardil), soybeans (aralac), and zine (vicara) are used as specialty fibers. Regenerated and modified cellulose products, including acetate, are still widely used today and the production of fibers is similar to that described above for synthetic fiber production. Most regenerated cellulose (rayon) is produced by the viscose process where an aqueous solution of the sodium salt of cellulose xanthate is precipitated in an acid bath. The relatively weak fibers produced by this wet spinning process are stretched to produce strong rayon. 

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 ... 

N-McLhylmorpholine-N-oxidc monohydrate, a tertiary, aliphatic amine N-oxide, is able to dissolve cellulose directly, i.e. without chemical derivatization, which is used on an industrial scale as the basis of the Lyocell process [ 1, 2], This technology only requires a comparatively low number of process steps compared for instance to traditional viscose production. Cellulose material - mainly fibers - are directly obtained from the cellulose solution in NMMO no chemical derivatization, such as alkalization and xanthation for rayon fibers, is required [3]. The main advantage of the Lyocell process lies in its environmental compatibility very few process chemicals are applied, and in the idealized case NMMO and water are completely recycled, which is also an important economic factor. Even in industrial production systems NMMO recovery is greater than 99%. Thus, compared with cotton and viscose the Lyocell process pertains a significantly lower specific environmental challenge [4]. Today, Lyocell fibers are produced on an industrial scale, and other cellulosic products, such as films, beads, membranes and filaments, are also currently being developed or are already produced commercially. 

Rayon. Viscose rayon, like cotton, is comprised of cellulose. In the manufacturing process, wood pulp is treated with alkali and carbon disulfide to form cellulose xanthate. Subsequently, the reaction mass is forced through a spinneret and precipitated in an acid coagulation bath as it is formed into a continuous filament. The fiber has a round striated cross-section. Rayon staple is made by breaking the continuous strands into staple-length fibers. Viscose rayon is conventionally produced in diameters varying from 9 to 43 microns. 

Fiber, rayon viscose A regenerated cellulosic fiber made by treating wood pulp with caustic soda, and with carbon disulfide to form cellulose xanthate that is then dissolved in a weak caustic solution. It is from the latter that extrusion and coagulation forms the fiber. 

Viscose vis- k6s [obs. viscose, adj, viscous] (1896) n. (1) A solution of xanthated cellulose in dilute sodium hydroxide from which rayon fibers and cellophane films are formed. The xanthated cellulose is produced by reacting alkali cellulose, i.e., wood fibers or cotton linters treated with sodium hydroxide, with oxygen and carbon disulfide. Rayon produced by this method is known as viscose rayon. (2) Generic name for fibers from regenerated cellulose (prepared by the xanthate method). Tortora PG (ed) (1997) Fairchild s dictionary of textiles. Fairchild Books, New York. 

Three British chemists discovered that cellulose could be solubilized when it was treated with sodium hydroxide and carbon disulfide. The product is called cellulose xanthate. The viscous solution was then extruded through a nozzle into an acidic solution, forming Instrons, silk-like fibers. They patented the process and commercialized the prodnct in 1894. This is rayon. It is chemically still cellulose, but its texture is different from that of cotton. It can be produced from not only from cotton, but also from any pulp. 

High-wet-modulus rayons (polynosic rayons) have been developed in recent years. These fibers are produced from high-grade cellulose starting materials, and the formation and decomposition of cellulose xanthate is carried out under the mildest of conditions to prevent degradation of the cellulose chains. 

Viscose rayon is produced by extruding a solution of cellulose xanthate, produced from "soda cellulose and carbon disulfide, into dilute acid, which breaks down the cellulose xanthate and reprecipitates the cellulose in a form suitable for spinning. Acetate rayon is produced by extruding a solution of cellulose acetate the organic solvent is eillowed to evaporate to leave a fiber of cellulose acetate. Cellulose acetate is also used in plastics and paints manufacture. Cellulose nitrate (nitrocellulose, guncotton) is used as a propellant. Ethers of cellulose are used as protective colloids (see p. 221) and as detergents. 

Wet spinning also involves pumping a solution to the spinneret. Now, however, the polymer is precipitated in an immiscible liquid. Polyacrylonitrile in dimethyl formamide, for example, can be precipitated by passing a jet of the solution through a bath of water, which is miscible with the solvent but causes the polymer to coagulate. Cellulose triacetate can be wet-spun from a methylene chloride-alcohol mixture into a toluene bath, where it precipitates. In other fibers, the precipitation can involve a chemical reaction. Viscose rayon is made by regenerating cellulose from a solution of cellulose xanthate. 

The important fiber rayon is simply regenerated cellulose from wood pulp that is in a form more easily spun into fibers. Cellophane film is regenerated cellulose made into film. One method of regeneration is formation of xanthate groups from selected hydroxy groups of cellulose, followed by hydrolysis back to hydroxy groups. 

It can also be made from sucrose by Acetobacter xylinum.71 This bacterial cellulose has high mechanical strength and might become an important material if the cost can be brought down. Regenerated cellulose fibers are known as rayon and regenerated films as cellophane. They are usually made by the xanthate process, which uses sodium hydroxide and carbon disulfide. 

Cotton is almost pure cellulose. Both rayon and acetate rayon are made from chemically modified cellulose and were the first commercially important synthetic textile fibers. In the production of rayon, cellulose-containing materials are treated with carbon disulfide, CSj, in aqueous sodium hydroxide. In this reaction, some of the —OH groups on a cellulose fiber are converted to the sodium salts of a xanthate ester, which causes the fibers to dissolve in alkali as a viscous colloidal dispersion. 

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