Kinetic Study on Thermal Degradation of Crosslinked Polyethylene Cable Waste

Kinetic study of the pyrolysis of waste plastic is crucial in the design of an efficient and predictable thermochemical conversion system amidst the huge amount of plastic waste being rejected daily. Here, the chemical kinetics of cross-linked polyethylene under pyrolysis condition is conducted. The thermal degradation of the cross-linked LDPE/Si-XLPE was investigated under two different conditions: dynamic and isothermal heating. Moreover, two popular models of Kissinger and Flynn–Wall–Ozawa were used to infer the activation energy and pre-exponential constant during the dynamic heating at different heating rates. The isothermal conditions were tested at four different temperatures and reaction times based on the Arrhenius kinetic parameters. Thermo-gravimetric results showed the main region of weight loss occurs between 450 and 480 °C which corresponds to the highest conversion rate. The computed activation energies were 290.26 kJ/mole and 287.56 kJ/mole for Kissinger and Flynn–Wall–Ozawa models, respectively. The dynamic heating produced slightly different values than the one obtained from isothermal heating. This is because the kinetic parameters are highly dependent on the reaction time. These results suggest that Si-XLPE, which is commonly used in the cable industry, follows a similar behavior to the LDPE. This was demonstrated by the detailed analysis of the composition, melting point, thermal stability and thermal degradation.