Kinetic data obtained from micro thermogravimetry and gradient free reactor experiments con"rm that di!erent molecular structures of commodity plastics bring about di!erent reaction mechanisms of thermal decomposition, di!erent reaction rates, and di!erent temperature dependencies of the decomposition rates. From that, stepwise pyrolysis of mixtures of plastics seems to be reasonable where the di!erent components of the mixture are pyrolysed at di!erent temperatures.
To perform a stepwise pyrolysis in laboratory scale a cascade of well stirred reactors has been developed where mixing of the reactor contents occurs by circulating of stainless steel spheres. Examples for the separation of single plastics by stepwise thermal decomposition of mixtures of poly(vinyl chloride), polystyrene and polyethylene are presented. In the "rst step hydrogen chloride from poly(vinyl chloride) is released, in the second step styrene from polysytrene is formed and in the third step aliphatic compounds from polyethylene decompositon are trapped.
Di!erences in the thermal degradation of single polymers and mixtures of polymers, e.g. in the apparent activation energies and preexponential factors, are investigated using mixtures and blends of polyethylene and polystyrene.