What is the difference between thermo plastic and thermo setting plastic?

ThermoplastIc materials (such as polyethylene, nylon, etc ) are melt-processable, meaning that they can be heated to a melt (liquid) phase, forced into a mold, and then cooled to form a pre-determined shape. Typical processes include injection molding, compression molding, and blow molding. Thermoplastic materials can, many times, be potentially ground up and re-processed many times as there is no chemical reaction that occurs. Thermoset materials (such as epoxy, and some polyesters), on the other hand, undergo a chemical reaction and cross-linking of the polymer chains and can not be can't be ground up and re-processed.