THERMAL-DECOMPOSITION OF LOW-DENSITY POLYETHYLENE IN THE PRESENCE OF CHLORINE-CONTAINING POLYMERS

The thermal decomposition of low-density polyethylene was studied on samples containing a few per cent of poly(vinyl chloride), poly(vinylbenzyl chloride) or poly(chlorostyrene), using thermogravimetry/mass spectrometry, pyrolysis-gas chromatography/mass spectrometry between 400 and 1000 degrees C, and FT-IR analysis of the pyrolysis tars. Reactive species evolving from the chlorine-containing polymers during their thermal degradation affect the decomposition reactions of polyethylene. Hydrogen chloride, formed from chloropolymers prior to the beginning of the PE thermal decomposition, promotes the initiating steps of thermal degradation and inhibits beta-scission of macroradicals. Chlorine evolves at a relatively higher temperature, and enhances dehydrogenation reactions leading to aromatic products.