PRODUCTION OF HARMFUL MATERIALS FROM SYNTHETIC-POLYMERS UNDER PYROLYSIS

Polyethylene samples were pyrolyzed together with small percentages of poly(vinyl chloride), poly(vinylbenzyl chloride) or poly(chlorostyrene) in a horizontal quartz furnace. Nitrogen was used as a carrier gas, and the trapped volatile pyrolysis products were analysed by GC/MS. The evolution of polynuclear aromatic hydrocarbons (PAHs) and chlorine-containing pyrolysis products was studied in the temperature range 400-1000 degrees C. The chlorine atom is cleaved from poly(vinylbenzyl chloride) and poly(chlorostyrene) under pyrolysis; in addition, depolymerization and side-group detachment occur. Hydrogen chloride and chlorine formed from the chlorine-containing part of the sample influence the thermal decomposition reactions of polyethylene. The effect of these reactive species is modified by iron or copper. Hydrogen chloride formed by elimination from PVC depresses the formation of PAHs more effectively in the presence of iron. Chlorine from poly(vinylbenzyl chloride) increases the production of PAHs in the presence of copper.