WHAT ARE THERMOSETTING AND THERMOPLASTIS POLYMERS

There are two types of plastics:

•  thermoplastics

• thermosetting polymers.

THERMOPLASTICS -

 Thermoplastics are the plastics that do not undergo chemical change in their composition when heated and can be molded again and again.
 Examples include polyethylene, polypropylene, polystyrene and polyvinyl chloride. Common thermoplastics range from 20,000 to 500,000 amu, while thermosets are assumed to have infinite molecular weight. These chains are made up of many repeating molecular units, known as repeat units, derived from monomers; each polymer chain will have several thousand repeating units.

THERMOSETS -

Thermosets can melt and take shape once; after they have solidified, they stay solid. In the thermosetting process, a chemical reaction occurs that is irreversible. The vulcanization of rubber is a thermosetting process. Before heating with sulfur, the polyisoprene is a tacky, slightly runny material, but after vulcanization the product is rigid and non-tacky.

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Posted By : Komal Rawat