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Concept
Rayon
Résumé
Rayon is a semi-synthetic fiber, made from natural sources of regenerated cellulose, such as wood and related agricultural products. It has the same molecular structure as cellulose. It is also called viscose. Many types and grades of viscose fibers and films exist. Some imitate the feel and texture of natural fibers such as silk, wool, cotton, and linen. The types that resemble silk are often called artificial silk.
The fibre is used to make textiles for clothing and other purposes. Rayon production involves solubilizing cellulose to allow turning the fibers into required form. Three common ways to solubilize are the cuprammonium process, not in use today, using ammoniacal solutions of copper salts; the viscose process, the most common today, using alkali and carbon disulfide; and the Lyocell process, using amine oxide. The last avoids the neurotoxic carbon disulfide of the viscose process but is also more expensive.
Rayon is produced by dissolving cellulose, then converting this solution back to insoluble fibrous cellulose. Various processes have been developed for this regeneration. The most common methods for creating rayon are the cuprammonium method, the viscose method, and the lyocell process. The first two methods have been practiced for more than a century.
Cuprammonium rayon
Swiss chemist Matthias Eduard Schweizer (1818–1860) discovered that cellulose dissolves in tetraaminecopper dihydroxide. Max Fremery and Johann Urban developed a method to produce carbon fibers for use in light bulbs in 1897. Production of cuprammonium rayon for textiles started in 1899 in the Vereinigte Glanzstoff Fabriken AG in Oberbruch near Aachen. Improvement by J. P. Bemberg AG in 1904 made the artificial silk a product comparable to real silk.
Cuprammonium rayon has properties similar to viscose; however, during its production, the cellulose is combined with copper and ammonia (Schweizer's reagent). Due to the detrimental environmental effects of this production method, cuprammonium rayon is no longer being produced in the United States.
Source officielle
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