Thermoplastics are plastics which can be moulded again and again. These plastics do not undergo any chemical change during the heating and moulding process. Examples include polyethylene, polystyrene, polyvinylchloride.
Thermosetting Plastics
In contrast, thermosetting plastics can be used only once. These plastics are chemically changed during the moulding process. They are hard and brittle. Examples of thermosetting plastics are bakelite, vulcanised rubber. Thermosetting plastics form cross links when heated. This gives them the hardness and ability to withstand high temperature. A property which makes them ideal for high temperature applications.