Viscose
Viscose is a solution of cellulose xanthate made by treating dissolving pulp with aqueous sodium hydroxide and carbon disulfide. Byproducts include sodium thiocarbonate, sodium carbonate, and sodium sulfide.[1] The viscose solution is used to spin the fiber viscose rayon, or rayon, a soft man-made fiber commonly used in dresses, linings, shirts, shorts, coats, jackets, and other outer wear; it is also used in industrial yarns (tyre cord), upholstery and carpets. It is also used in the casting of Cellophane.
Manufacture
Viscose rayon is a fiber of regenerated cellulose; it is structurally similar to cotton. Cellulose is a linear polymer of β-D-glucose units with the empirical formula (C6H10O5)n.[2] To prepare viscose, dissolving pulp is treated with aqueous sodium hydroxide (typically 16-19% w/w) to form "alkali cellulose," which has the approximate formula [C6H9O4-ONa]n. The alkali cellulose is then treated with carbon disulfide to form sodium cellulose xanthate.[3]
- [C6H9O4-ONa]n + nCS2 → [C6H9O4-OCS2Na]n
The higher the ratio of cellulose to combined sulfur, the lower the solubility of the cellulose xanthate. The xanthate is dissolved in aqueous sodium hydroxide (typically 2-5% w/w) and allowed to depolymerize to a desired extent, indicated by the solution's viscosity. The rate of depolymerization (ripening or maturing) depends on temperature and is affected by the presence of various inorganic and organic additives, such as metal oxides and hydroxides.[3] Air also affects the ripening process since oxygen causes depolymerization.Cite error: A <ref> tag is missing the closing </ref> (see the help page). In 1893 they formed the Viscose Syndicate to grant licences, and in 1896 formed the British Viscoid Co. Ltd. to exploit the process.[4]
Products made from viscose
References
- ^ Wyss, George de (1 October 1925). "The Ripening of Viscose". Industrial & Engineering Chemistry. 17 (10): 1043–1045. doi:10.1021/ie50190a018.
- ^ Booth, Gerald (2000). Dyes, General Survey. Wiley-VCH. doi:10.1002/14356007.a09_073.
- ^ a b Wheeler, Edward (1928). The Manufacture of Artificial Silk With Special Reference to the Viscose Process. New York: D. Van Nostrand company.
- ^ Woodings, Calvin R. "A Brief History of Regenerated Cellulosic Fibres". WOODINGS CONSULTING LTD. Retrieved 26 May 2012.
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