Thermal Decomposition Kinetics of Poly(L-lactic acid) after Heat Treatment

ABSTRACT

Thermal decomposition behavior of Poly(L-lactic acid) (PLLA) and PLLA composites after different heat treatment were investigated using thermogravimetric analysis. Firstly, the thermal decomposition results of neat PLLA showed that the decomposition of PLLA was a first-order kinetic reaction, and thermal decomposition kinetics indicated that the heat treatment significantly affected activation energy of thermal decomposition of PLLA. The measurement results also exhibited that the onset decomposition temperature of PLLA treated below 115 °C was lower than that of the pristine PLLA. Then, the effect of additive CaCO₃ on the thermal decomposition behavior of PLLA was evaluated. The addition of CaCO₃ could significantly improve the crystallization performance of PLLA, but the CaCO₃ did not change the decomposition trend of PLLA, and the thermal decomposition behavior of PLLA/CaCO₃ composites after isothermal heat treatment was similar to that of PLLA. However, the thermal decomposition activation energy of PLLA/CaCO₃ is lower than that of PLLA.

Keywords:

Calcium carbonate, composites, crystallization, poly(L-lactic acid), thermal decomposition kinetics.