Kinetic study of high density polyethylene (HDPE) pyrolysis

In this study, 15 mg samples of high density polyethylene (HDPE) were pyrolysed in an isothermal thermogravimetric set-up in a micro-thermobalance reactor with pre-set temperatures. The objective was to study the thermal degradation behaviour of the polymer and determine the kinetic rate constants and overall activation energy (Eo). Yielded pyrolysis products under different temperatures were analyzed and lumped into the following categories: rich gases (C1–C4), liquids (non-aromatic C5–C10), aromatics (single ring structures), waxes (C11) and char. It was observed that the gas yield was increasing with the operating temperature. Data obtained enabled us to propose a novel kinetic modelling approach based on the thermal cracking of the polymer by primary and secondary depolymerisation reactions to form the pyrolysis products. The Eo was estimated to be 147.25 kJ mol−1 for the total conversion of HDPE in isothermal pyrolysis.