Thermal degradation kinetics of sucrose palmitate reinforced poly(lactic acid) biocomposites

The current work is focused on investigating the influence of novel bio-filler, “sucrose palmitate (SP)” on the thermal degradation behavior of poly(lactic acid) (PLA) biocomposites in order to render its suitability for food packaging application. Thermal degradation behavior of the PLA biocomposites was investigated by thermo-gravimetric analysis (TGA) using dynamic heating regime. The differential TG analysis revealed that there is no change in the Tmax value (357 °C) for PLA and its composites up to 5 wt% of bio-filler loading. This reveals that the sucrose palmitate acts as a protective barrier by decelerating the thermal degradation rate of PLA. In the case of 10 wt% of the filler incorporated in the PLA matrix, Tmax rapidly shifted to lower temperature (324 °C). This downturn in Tmax at higher loading of the filler is due to the increase in acidic sites and enhancement in the rate of degradation is observed. Differential scanning calorimetry (DSC) analysis revealed unimodal melting peak indicating the α-crystalline form of PLA. Based on the thermal degradation profile of sucrose palmitate, possible mechanism for degradation of PLA composites is proposed. The activation energies (Ea) of thermal degradation of PLA and PLA composites were evaluated by Flynn-Wall-Ozawa and Kissinger methods.