Rayon is a fiber that comes from organic materials and is processed just like cotton.
Rayon is not processed just like cotton at all.
Rayon is a synthetic fiber made from high-cellulose organic stuff (mostly wood). You can see how sophisticated process of rayon production is (Wikipedia):
First, cellulose is prodused:
Viscose - Wikipedia, the free encyclopedia
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.[4]
Rayon fiber is produced from the ripened solutions by treatment with a mineral acid, such as sulfuric acid. In this step, the xanthate groups are hydrolyzed to regenerate cellulose and release dithiocarbonic acid that later decomposes to carbon disulfide and water:
Then -Rayon is produced:
Rayon - Wikipedia, the free encyclopedia
Production method
Regular rayon (or viscose) is the most widely produced form of rayon. This method of rayon production has been utilized since the early 1900s and it has the ability to produce either filament or staple fibers. The process is as follows:
1. Cellulose: Production begins with processed cellulose
2. Immersion: The cellulose is dissolved in caustic soda: (C6H10O5)n + nNaOH → (C6H9O4ONa)n + nH2O
3. Pressing: The solution is then pressed between rollers to remove excess liquid
4. White Crumb: The pressed sheets are crumbled or shredded to produce what is known as "white crumb"
5. Aging: The "white crumb" is aged through exposure to oxygen
6. Xanthation: The aged "white crumb" is mixed with carbon disulfide in a process known as Xanthation, the aged alkali cellulose crumbs are placed in vats and are allowed to react with carbon disulfide under controlled temperature (20 to 30 °C) to form cellulose xanthate: (C6H9O4ONa)n + nCS2 → (C6H9O4O-SC-SNa)n
7. Yellow Crumb: Xanthation changes the chemical makeup of the cellulose mixture and the resulting product is now called "yellow crumb"
8. Viscose: The "yellow crumb" is dissolved in a caustic solution to form viscose
9. Ripening: The viscose is set to stand for a period of time, allowing it to ripen: (C6H9O4O-SC-SNa)n + nH2O → (C6H10O5)n + nCS2 + nNaOH
10. Filtering: After ripening, the viscose is filtered to remove any undissolved particles
11. Degassing: Any bubbles of air are pressed from the viscose in a degassing process
12. Extruding: The viscose solution is extruded through a spinneret, which resembles a shower head with many small holes
13. Acid Bath: As the viscose exits the spinneret, it lands in a bath of sulfuric acid, resulting in the formation of rayon filaments: (C6H9O4O-SC-SNa)n + ½nH2SO4 → (C6H10O5)n+ nCS2 + ½nNa2SO4
14. Drawing: The rayon filaments are stretched, known as drawing, to straighten out the fibers
15. Washing: The fibers are then washed to remove any residual chemicals
16. Cutting: If filament fibers are desired the process ends here. The filaments are cut down when producing staple fibers[1]
