21 September 2014

Synthetic Fibres: NCERT Science

Synthetic Fibres: NCERT / CBSE Revision Science Notes

All fabrics are materials made from many fibres, which are obtained from natural or artificial sources.
Cotton is a natural fibre obtained from the cotton plant. All synthetic fibres are man-made fibres that are prepared by a number of processes using raw material of petroleum origin, called petrochemicals.

Many small units or monomers combine to form a larger unit called a polymer. (Pause) Polymer is a Greek word, formed by the combination of ‘poly,’ which means many, and ‘mer,’ which means part or unit. Thus, a polymer is made up of many repeating units called monomers.

Synthetic Fibres, NCERT / CBSE Revision Science Notes, Class 8
Cotton is a form of polymer called cellulose, which is made of a large number of glucose units.

Must Read : Fibers

Characteristics of synthetic fibres:

  • Dry quickly
  • Very durable
  • Less expensive
  • Easy to maintain
  • Readily available

A big disadvantage of synthetic fibres is that they melt on heating. If synthetic material catches fire, the fabric melts and sticks to the body of the person wearing it. This is extremely dangerous, and that is why it is important not to wear synthetic clothes in the kitchen or laboratory. 
Fibre obtained by chemically treating wood pulp is called rayon or artificial silk. Rayon cannot be called a natural fibre as it is man-made.

Characteristics of rayon:

  • Cheaper than silk and can be woven like silk fibres.
  • Highly absorbent, soft and comfortable.
  • Easy to dye in a wide range of colours, and drapes well.

Uses of rayon:

  • Widely used in all types of clothing and home furnishings.
  • Mixed with cotton to make bed sheets and curtains, or with wool to make carpets.
  • Nylon is a synthetic fibre made from coal, water and air.
  • Nylon is b, elastic, light, very lustrous and easy to wash. It dries quickly and retains its shape.

Uses of nylon:
  • To make seat belts in cars, curtains, sleeping bags, tents, tooth brushes, socks and ropes,
  • To make parachutes and ropes for rock-climbing.


Polyester is a synthetic fibre, derived from coal, air, water and petroleum.
Polyester is made of repeating chemical units called esters.


Polycot is a mixture of polyester and cotton, and poly wool is a mixture of polyester and wool.
Fabric made from polyester retains its shape and remains crisp. Polyester is easy to wash and dry.


Terylene is a popular form of polyester, which can be drawn into very fine fibres. These fibres can be woven like any other yarn. PET or poly-ethylene terephthalate, is another familiar form of polyester, which is used to make bottles, utensils, films and wires. Polyester is also used for making hoses, ropes, nets, thread, raincoats, fleece jackets, clothing and medical textiles.


Acrylic is a synthetic polymer of methyl methacrylate. Fabric made from acrylic is warm to wear, retains its shape and is durable. Acrylic is easy to wash and dries quickly. 
Acrylic is used in apparel like sweaters and socks, and in home furnishings such as furniture, carpets, blankets and upholstery fabrics. Industrial uses of acrylic include craft yarns, awnings, boat and vehicle covers, and luggage.