Types Of Synthetic Fibers
Animal fibres of Class 7
Different Types Of Synthetic Fibers
(A) Rayon or Artificial Silk
Naturally silk was very expensive there for artificial silk was always in demand to fulfill this demand scientist made product similar to silk that is rayon The raw material for the production of rayon is pure cotton or wood cellulose. Rayon is sometimes called regenerated fibre, because it is produced by modifying the natural fibre. Rayon is not truly an artificial fibre, because its raw material is a natural fibre. However, for all practical purposes it included into man-made fibre or synthetic fibre.
Rayon is produced from the natural fibre in the following steps:
- Pure cotton or cellulose is soaked in 30% solution of caustic soda for three hours.
- The caustic soda solution is then removed and the product is gently warmed with carbon disulphide. The product so formed is called cellulose xanthate.
- Cellulose xanthate is again dissolved in caustic soda solution, when it forms another product commonly called viscose solution. This solution is carefully filtered to remove any insoluble impurities.
- The viscose solution is then slowly passed through a spinneret placed in the bath of dilute sulphuric acid. The viscose hardens to form a very fine filament. The filament is then wound on a spool.
It is a superior type of synthetic fibre, which is truly artificial, as it does not use any natural fibre as its raw material. It is prepared by the polymerisation of amide molecules. The amide molecules are obtained from petroleum products by complex chemical process. The nylon fibre consists of a very long chain of polyamide molecules. The nylon fibres are elastic, strong and water resistant.
The term Nylon used for polyamide molecules is named after two cities, New York in USA and London in Great Britain. NY stands for New York and Lon for London. It is because this product was developed by the collective effort of scientists of two countries.
Esters are the compounds formed, when alcohol is made to react with organic acids, such as acetic acid, pthalic acid. The esters have fruity smell. The ester molecules can be polymerised to form polyester. The polyester can be drawn into very fine filaments so as to form artificial fibre. There are a number of varieties of esters, depending upon the alcohol and the organic acid used to form the molecules of ester.
Terylene or Terene or Dacron
These polymers are obtained by polymerising the molecules of pthalic acid and ethene glycol. Terylene filaments are similar, but superior in properties than nylon.
The fibre is widely known as Terylene (ICI trade name) or Dacron (Dupont trade name). The polyester fibres possess good crease resistance and wash and wear properties. A sizable fraction of the polyester fibre is used as the reinforcing cord in the tyre and related industry.
Polyethene Tetraphthalate [PET]
It is prepared by the polymerisation of ethene tetraphthalate. It can be easily drawn into very fine filaments, which can be woven like any other yarn.
(D) Acrylic Fibres (Acryion or Orion)
Acrylic fibre is obtained by the polymerisation of molecules of acrylonitrite (which is a complex molecule obtained by complex chemical processes from petroleum products). These fibres are very light and soft like wool. They are resistant to weathering.