Pyrolytic degradation kinetics of HIPS, ABS, PC and their blends with PP and PVC

Abstract

The thermal behavior and pyrolytic degradation kinetics of main engineering polymers, high impact polystyrene (HIPS), acrylonitrile-butadiene-styrene (ABS) and polycarbonate (PC) and their blends with polypropylene (PP) and poly(vinyl chloride) (PVC), representing typical plastic parts of waste electrical and electronic equipment (WEEE) were studied. Thermogravimetry (TG) pyrolysis experiments revealed that the thermal degradation of HIPS and PC occurred in a single step, whereas that of ABS and both blends underwent a two-consecutive, partially overlapping degradation steps, whose peaks related to the first-order derivative of TG were deconvoluted into two distinct processes. The first blend (HIPS, ABS, PC, PP) showed a thermal degradation reliance of the single polymer components, whereas this was not observed in the second blend (HIPS, ABS, PC, PP, PVC) investigated. A kinetic analysis was made using either the integral isoconversional method of Kissinger-Akahira-Sunose (KAS) or the differential Friedman method. Both blends exhibit low activation energies in the first degradation step (near 90 kJ/mol) whereas much higher (in the vicinity of 200 kJ/mol) in the second.