Rayon is prepared by the Viscose process.
The Viscose process is a method used to produce rayon, a versatile synthetic fiber. It involves the following steps:
1. Cellulose Extraction:
- Cellulose is extracted from wood pulp or cotton linters.
- Wood pulp is treated with chemicals to remove impurities and break down the cellulose into a more soluble form.
2. Alkali Treatment:
- The cellulose is treated with an alkali solution, usually sodium hydroxide (NaOH), to further break it down.
- This process is known as mercerization and improves the reactivity of cellulose.
3. Xanthation:
- The treated cellulose is then soaked in a solution of sodium hydroxide and carbon disulfide (CS2).
- This converts the cellulose into a compound called sodium cellulose xanthate.
4. Viscose
- The sodium cellulose xanthate is dissolved in a dilute solution of sodium hydroxide to form a viscose solution.
- This solution has a syrup-like consistency and can be spun into fibers.
5. Filament Formation:
- The viscose solution is forced through spinnerets, which are small holes, to form fine filaments.
- The filaments are then coagulated in a bath of sulfuric acid (H2SO4) to solidify the rayon fibers.
6. Washing and Finishing:
- The solidified fibers are washed to remove any residual chemicals.
- They are then treated with chemicals to improve their strength, flexibility, and other desired properties.
- The fibers can be further processed into various forms, such as yarn or fabric.
In conclusion, rayon is prepared by the Viscose process, which involves extracting cellulose from wood pulp or cotton linters, treating it with alkali, xanthating it with sodium hydroxide and carbon disulfide, dissolving it in sodium hydroxide solution to form a viscose solution, spinning it into filaments, coagulating the filaments, washing and finishing the solidified fibers.