A thermoplastic is a material, usually a plastic polymer, which becomes soft when heated and hard when cooled. Thermoplastic materials can be cooled and heated several times without any change in their chemistry or mechanical properties. When thermoplastics are heated, they melt to a liquid. They freeze to a glassy state when cooled enough.
Thermoplastic materials have many features. Some products made from thermoplastic materials are used for electronic applications. They protect against electrostatic discharge and radio frequency interference. Thermoplastics are one of the main two types of plastics.