18.8.18

What is plastic? Types of plastics?

What is plastic?

Plastics are long Chain synthetic polymers having Isotropic Characteristics.
They have great tendency to deform, also high strength stiffness.
Plastics are formed by the Addition polymerization or Condensation polymerization.


Addition polymerization:-

In Addition polymerization process breaking the double carbon bond in Bi-functional polymers so that chain can be formed.
Various monomers used in this process such as Ethylene, Styrene, Vinyl Chloride, Propylene.


Condensation polymerization.

In Condensation polymerization process two different organic molecules reacts to form plastic molecule.

There are two main types of plastics:

Thermoplastic
Thermosetting plastic

Thermoplastic

Plastics that become soft on heating and melt on heating and can be moulded again and again are known as thermoplastics. Repetitive heating of thermoplastics does not cause permanent change in properties or composition. They are addition polymers. For example, Polypropylene, Polyethene, Polystyrene, Nylon, PVC, PVA, etc…

Thermosetting plastic

These are the plastics that can be softened on heating but they become permanently hard on cooling. They cannot be remoulded again. They are insoluble in any solvent whether organic or inorganic. They are condensation polymers. For example, Bakelite, Urea aldehyde, Silicones, etc…

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