Kinetic study of Pyrolysis of Low Density Polyethylene using Thermogravimetric Analysis: Dynamic study

Résumé

Presently, waste management is a problem for large African cities. The solid waste produced by the populations contains a lot of plastic waste. This plastic waste is unfortunately not biodegradable. Pyrolysis seems to be a promising way for their valorization. The control of the thermal kinetics is necessary to optimize the pyrolysis reaction of polyethylene (PE). It is indeed useful in the optimal design and operation of pyrolysis reactors.

The objective of this study is to analyze the kinetics of the pyrolysis of Low Density Polyethylene (LDPE) in dynamic regime. Thermogravimetric analysis (TGA) was used under argon atmosphere at different heating rates 5, 10, 20, 30, 40 and 50 °C min^-1. This work aims to analyze the use of simple kinetic models to describe the thermal behavior of the material, taking into account the complex mechanism of the reaction. Due to the complexity of this mechanism, the reaction order of the LDPE pyrolysis was determined. Freidman's method was used to obtain the kinetic parameters from non-isothermal experiments and compare them with values obtained by other authors.

The LDPE degradation temperatures with which the maximum mass losses (Tp) are associated are approximately 470, 490, 500, 505, 510 and 516 °C for heating rates of 5, 10, 20, 30, 40 and 50 °C min^-1, respectively. The best results from this study are obtained for reaction orders n varying with the heating rate.

 Keywords: Thermogravimetric analysis; Reaction kinetic; Activation energy; Reaction order; LPDE.