Chapter-Chapter 3. Synthethic Fibres and Plastics Science class 8 in english Medium CBSE Notes

Chapter 3. Synthethic Fibres and Plastics

Fibre: A thread or filament like structure which is obtained from vegetable tissues or chemical substance is called fibre.

All fabrics are made up of yan which small unit is fibre.

Fabric ⇒ Yan ⇒ Fibre 

​

Types of fibres: 

(i) Synthetic fibres: The fibres which are made by the human beings is called synthetic fibres.

Example: Rayon, Nylon, polyester and Acrylic.

(ii) Natural fibres: The fibres which are obtained from plants and animal resources are called natural fibres. 

Example: Cotton, Wool and Silk.

Polymers: The small units of fibres which is actually a chemical substance, such many small units combine to form a large single units is called a polymer.

Ex. Cellulose, Nylon, polyester etc.

bead units and paper click here form a long chain just like polymers. 

Polymers are also two types: 

(I) Natural polymers : Cellulose (cotton) is a natural polymer. 

(ii) Synthetic Polymers : Nylon and polyster etc. 

Cellulose : Cellulose is a special kind of carbohydrates (glucose molecules) which naturally obtained from plants. 

History of silk: Silk is a natural fibre which obtained from silkworm and It was discovered in China many many years ago. Chinese kept discovery of silk as a closely guarded secret for a long time. Later silk reached all over the world through China. 

Features of Silk: 

(i) Fabric obtained from silk fibre was very costly.

(ii) Its beautiful texture fascinated everybody.

(iii) It is very soft fibres but very strong. 

(iv) It is also a natural fibre which obtained from silkworm. 

Types of Synthetic Fibres: 

(A) Rayon:

(B) Nylon:

(c) Polyster and Acrylic