Evaluation of the pro-degradant systems in the thermooxidative degradation of HDPE

Abstract

The evaluation of pro-degradant systems based on iron and manganese in the form of metallic stearate, and d2w^TM commercial additive, based on organic salt of manganese, was carried out on films of high density polyethylene (HDPE) in thermal oxidative conditions (80 °C oven and absence of light). The thermo oxidative degradation was monitored by mechanical properties, by infrared spectroscopy and by size exclusion cromatography. The results show that both metals accelerate thermal oxidative degradation of HDPE. However, the pro-degrading performance of manganese is significantly higher than iron. Considering iron, the degradation increases with increasing concentration of the metal, while manganese presents the maximum value of degradation depending on the concentration. The oxidation state of iron does not interfere with pro-degrading performance. The commercial additive d2w^TM significantly accelerates HDPE thermo-oxidation, but its performance is lower than manganese stearate as a function of the set of stabilizing additives to be added to the commercial product.

Keywords:
degradation; HDPE; iron stearate; manganese stearate; pro-degradant