Thermal degradation kinetics of industrial batch crosslinked polyethylene.

Polyethylene (PE) is one of the most used polymers which can be applied since to flexible packaging to general goods industries, representing 32% of the total market share. Crosslinking PE (XPE) is of considerable practical importance since it increases the upper application temperature limit and improves mechanical performance. The objective of this work was to investigate the thermal degradation kinetics in inert (nitrogen) and oxidative (oxygen) environments of XPEs industrial formulations, with the crosslinking agent content between 0% and 1.5%. PE and XPE specimens were characterized by thermogravimetry (TG) and the computed data modeled using ASTM E698. Increasing the heating rates shifted the degradation rate (dα/dt) and weight loss to higher temperatures, whereas XPEs showed greater thermal stability related to PE. Deconvolution of derivative thermogravimetry (DTG) peaks displayed to be an important tool during kinetics analysis providing understanding and reliable data which affords excellent fits between theoretical and experimental data. In plots acquired using ASTM E698 the degradation activation energy (Ea) increased along with the degradation; morphological and structural changes are suggested in the higher Ea range. Among investigated compounds, 0.5XPE presented the best performance, that is, the greatest thermal stability in both atmospheres. [ABSTRACT FROM AUTHOR]