Flat discs, normal row ISO 7089-poliammide 8,4

Plastics differ from polymers due to the addition of additives. Typical additives include plasticisers, stabilisers, colourants, fillers and reinforcing agents. Plastics can be classified according to various criteria, e.g. molecular synthesis, molecular structure, chemical origin or, based on their mechanical and thermal behaviour, into the three main groups: thermoplastics, thermosets and elastomers.