Model-free kinetics analysis of waste PE sample

Vyazovkin model-free approach is applied to study non-isothermal decomposition of waste PE sample using various temperature integral approximations such as Coats and Redfern, Gorbachev, Agrawal & Siva Subramanian and a new approximation [J. Cai, F. Yao, W. Yi, F. He, AIChE J. 52 (2006) 1554] and a new method for direct integration.Eα dependency on α is compared with several literature data. Initial strong and increasing Eα dependency on α in case of non-isothermal decomposition is associated with initiation at the weak links. Weak but increasing Eα dependency on α in the later stages is possibly due to dependence of distribution of size of volatile products on heating rate and random scission. Weak and decreasing followed by weak but increasing function of α in case of isothermal decomposition is possibly due to existence of two opposite effects, nucleation, and distribution of size of volatile products. The sample used follows neither perfectly the LDPE trend nor the HDPE trend. Thus, it becomes mandatory to study the decomposition behaviour of any waste material before design of an incinerator and/or pyrolysis unit without using blindly the information available for standard samples. Optimum Eα dependencies from non-isothermal data at 15 K min−1 heating rate best predicted the isothermal data.