Plastics is a class of substance which is hard and tough. The usage of plastics is widely accepted throughout the world because it is light in weight and has relatively higher strength than most and other materials.

Classification of plastics:
Plastics can be classified into two types.
(a) Thermoplastics
(b) Thermos Setting Plastic

Thermoplastics:

The characteristics of thermoplastics is that they get softened under heat and again get hardened when cooled. This process can be repeated several times without anyappreciable loss in physical properties. Due to this reason thermoplastics are not subjected to chemical change by heating.

Thermos Setting Plastics:

This kind of plastics get softened by the application of heat and undergo an internal change which makes them hard and is resistant to any further application of heat.