The polyethylene terephthalate belongs to the family of polyesters. It is a thermoplastic resin suitable to food contact. According to its production processes and to its thermic history it can be in amorphous form (transparent) or in semi-crystalline form (white and opaque). It is used also for its electrical properties, its chemical resistance, its performances at high temperatures, its self-extinguishing properties, its moulding rapidity. Polyesters are flammable, but, due to their intrinsic thermoplasticity, they are apt to burn with a self-extinguishing flame. The PET decomposes at 340° C.