The plastic which do not remould against on the heating are called ___ ...

Thermoseeting is termed to the plastic which caanot be remouled by heating, hence reausing them is not possible effeciently hence must be avoided to use in day to day applciations.

bakelite is an an examle

The reverse of the "thermosettin" are "thermoplastic" which can be remolded and are good for long time use.