Kinetic analysis of thermal degradation of biodegradable and biobased PLA/PHB blends

Abstract

In this study, the thermal stability and thermal degradation kinetics of poly(lactic acid)/poly(3-hydroxybutyrate) (PLA/PHB) blends, with a mass ratio of 70:30, were investigated using thermogravimetric analysis (TGA) under a nitrogen atmosphere at four different heating rates (5, 15, 30, and 50 °C/min). The thermogravimetric curves indicated two-step degradation processes for the polymer blends, suggesting immiscibility or partial miscibility between them. Degradation kinetic parameters were studied in the temperature range of 30 to 550 °C using the isoconversional methods of Kissinger-Akahira-Sunose (KAS) and Vyazovkin under non-isothermal conditions. An improvement in the thermal stability of the polymers upon blending was observed, as evidenced by higher activation energies for PLA and PHB in the blended materials.