Kinetics of Thermo-oxidative Degradation of Polymer Blends Based on Polylactide

The polyethylene-polylactide polymer blends of various compositions, including those with the addition of subjected to aging polyethylene are obtained and studied. The dependence of the samples' morphology on the blend composition was revealed by scanning electron microscopy. The process of thermal oxidation is investigated at temperatures of 80, 90, and 110 degrees C and at a pressure of 300 Torr. It is found that the oxidation rate increases with increasing temperature, at that the oxygen uptake rate by pure polyethylene is higher than that in mixtures with polylactide. The introduction of an aged polyethylene in an amount of up to 30 wt % as the third component accelerates the thermal oxidation of blends, but does not change the shape of the kinetic curves of oxygen uptake. It is determined that after 25 h of oxidation at 110 degrees C, polyethylene undergoes thermal oxidation, and in polylactide the supermolecular structure is rearranged.