Sunday, December 27, 2015

Advantage & Disadvantage of Synthetic Fibers

Advantages of Synthetic Fiber : 

1. A great advantage of synthetic fibers is that they are more durable than most natural fibers. 
2. Many synthetic fibers offer consumer-friendly functions such as stretching, waterproofing and stain resistance.
3. Synthetic fibers are not a good source for these fabric-damaging insects.
4. Synthetic fibers do not break down easily when exposed to light, water, or oil.
5. Modern synthetic fabrics can look and as luxurious as silk or wool.

Disadvantages of Synthetic Fiber :

1. Synthetic fibers burn more readily than natural.
2. More electrostatic charge is generated by rubbing than with natural fibers. 
3. Prone to heat damage. Melt relatively easily.
4. Not skin friendly, so uncomfortable for long wearing.
5. Allergic to some people.
6. Non-biodegradable in comparison to natural fibers.

Viscose Rayon :

Viscose is both a semi-synthetic fabric formerly called viscose rayon or rayon and a solution of cellulose xanthate produced by treating dissolving pulp with aqueous sodium hydroxide and carbon dssulfide used to spin the viscose rayon fiber. Byproducts of the production process include sodium thiocarbonate, sodium carbonate, and sodium sulfide. Viscose rayon fiber is a soft fiber commonly used in dresses, linings, shirts, shorts, cats, jackets, and other outer wear, it is also used in industrial yarns, unholstery and carpets. It is also used in the casting of Cellophane.

Manufacture of Viscose Rayon :

Viscose rayon is a fiber of regenerated cellulose, it is structurally similar to cotton but may be produced from a variety of plants such as soy, bamboo, and suger cane, Cellulose is a linear polymer of β-D-glucose units with the empirical formula (C6H10O5)n. To prepare viscose, dissolving pulp is treated with aqueous sodim 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.

                        [C6H9O4-ONa]n + nCS2 → [C6H9O4-OCS2Na]n

Rayon fiber is produced from the ripnened 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.

[C6H9O4-OCS2Na]2n + nH2SO4 → [C6H9O4-OH]2n +2nCS2 + nNa2SO4
                                      H2COS2 → H2O + CS2

Aside from regenerated cellulose, acidification given hydrogen sulfide, sulfur. and carbon disulfide. The thread made from the regenerated cellulose is washed to remove acid. The sulfur is then remoyed by the addition of sodium sulfide solution and impurities are oxidized by bleaching with sodium hypochlorite solution.

No comments:

Post a Comment