Question

How rayon or artificial silk is produced? Write its uses

Answer 1

Hint: Silk, attained from silkworms, comes under the category of natural fibres. On the other hand, rayon or artificial silk is a man-made fibre due to which it comes under the category of semi-synthetic fibres.

Complete step by step answer:
Owing to the expensiveness of natural silk, efforts were made to prepare artificial silk (also known as rayon) from the natural raw materials like cellulose through a chemical treatment method. The raw material for making rayon is generally acquired from wood pulp. Viscose is formed by dissolving the wood pulp in an alkaline solution. Viscose is then passed through the metallic cylinder into a sulphuric acid solution and a silk thread of rayon is formed. The chemical reactions for the production of rayon is depicted below:
\[
{{{(}}{{{C}}_{{6}}}{{{H}}_{{{10}}}}{{{O}}_{{5}}}{{)}}_{{n}}}\xrightarrow{{NaOH}}{{{[}}{{{C}}_{{6}}}{{{H}}_5}{{{(OH)}}_{{4}}}{{ - ONa]}}_{{n}}} \\
{{{[}}{{{C}}_{{6}}}{{{H}}_5}{{{(OH)}}_{{4}}}{{ - ONa]}}_{{n}}} + nC{S_2} \to {{{[}}{{{C}}_{{6}}}{{{H}}_5}{{{(OH)}}_{{4}}}{{ - OC}}{{{s}}_2}{{Na]}}_{{n}}} \\
{{{[}}{{{C}}_{{6}}}{{{H}}_5}{{{(OH)}}_{{4}}}{{ - OC}}{{{s}}_2}{{Na]}}_{{n}}} + n{H_2}S{O_4} \to {{{[}}{{{C}}_{{6}}}{{{H}}_5}{{{(OH)}}_{{4}}}{{ - OH]}}_{{{2n}}}} + 2nC{S_2} + nN{a_2}S{O_4} \\
\]
Rayon is actually made from the naturally occurring polymer that is present in the wood pulp due to which it is considered as a semi-synthetic fibre. The rayon filaments can be woven like other natural fibres. Its uses are mentioned below:
1. Rayon filaments can be blended with the wool to make carpets.
2. Rayon filaments can be blended with cotton to manufacture smooth silk cloth that is employed to make bed sheets, blankets and curtains.
3. Rayon filaments are used in the manufacturing of clothing including sarees, dresses, socks, etc.
4. Long filaments of the rayon are generally used in the manufacture of reinforced automobile tyres.
5. Rayon is also employed in medical industries to make surgical dressings and bandages.

Note: Rayon is much cheaper in comparison to natural silk but can be woven just like silk fibres. Rayon fibre is actually chemically identical to the cotton fibre but possesses shine like that of natural silk. That is why rayon is known as artificial silk.