Investigation of the Kinetics of Pyrolysis of PVC by TG-MS-Analysis

ABSTRACT Pyrolysis or combustion of plastics are of interest from different points of view: on the one hand polymers from which harmful substances may arise are involved in fires or are fed to incinerators; on the other hand plastic refuses are an alternative resource of energy or chemical raw materials. For designing recycling procedures the behaviour of the decomposition of polymers with regard to the decomposition products and the kinetics of decomposition must be known. Plastic refuses encompass chlorine- and/or nitrogen-containing polymers which may form toxic or corrosive products under pyrolytic conditions or in combustion. These components must be separated before processing or the troublesome elements have to be eliminated by pretreatment. The aim of this work was to investigate the kinetics of pyrolysis of polyfvinyl chloride) and mixtures of poly(vinyl chloride) with polyethylene, polypropylene, polystyrene and polyamide 6. By means of simultaneous thermogravimetry-mass spectrometry the kinetic parameters for the decomposition were determined and the products formed in decomposition of the polymers were identified. Because of the different reaction mechanisms and reaction rates and particularly their different temperature dependence, the single components decompose at different temperatures. This is important for the behaviour of plastic mixtures in fires. Furthermore a separation of plastic mixtures by temperature-controlled pyrolysis in recycling processes is possible.