Kinetics of thermal degradation of polylactic acid under N2 atmosphere

Kinetics of thermal degradation of polylactic acid (PLA), a biodegradable and bioabsorbable polyester, under atmosphere of inert gas has been investigated. Isothermal and dynamic heating techniques of thermogravimetry have been used in this study. The weight loss data versus time were recorded at the temperatures of 180, 200, 220, 240, 260 and 280 °C, in the isothermal heating experiments. Also, the weight loss data versus temperature were collected in dynamic heating runs conducted with the heating rates of 10, 15, 20 and 25 °C/min. Two kinetic models, one for isothermal and the other for dynamic heating experiments were utilized to fit the data. It is elucidated that the thermal degradation of PLA is a single stage process within the range 0-30% of weight loss, having activation energy of 21-23 kJ/mol.