Thermal and thermo-oxidative degradation kinetics and characteristics of poly (lactic acid) and its composites

Thermal degradation behavior and kinetics of starch/PLA composites in an inert and oxygen atmosphere were investigated by TG and TG-FTIR techniques. It is shown that the thermal degradation process can be divided into three stages, and a significant difference between thermal and thermo-oxidative degradation is the third stage in which the residual chars are further cracked for the thermo-oxidative degradation. The activation energy was calculated using the iso-conversional Flynn-Wall-Ozawa (FWO) method. The lower activation energy for thermo-oxidative degradation indicated that oxygen had an accelerated effect on thermal degradation. The variation of activation energy indicated that the decomposition of all the samples was a complex process that included at least two different mechanisms. Evolution of the evolved gaseous products with temperature was studied to understand the thermal and thermooxidative decomposition comprehensively. According to the TG-FTIR analysis, the gaseous products mainly contained lactide, cyclic oligomers, aldehydes, CO2, CO, and H2O. (C) 2019 Elsevier Ltd. All rights reserved.