The different molecular weight Poly(L-lactic acid) (PLLA) was investigated by differential scanning calorimetry (DSC) under different cooling rates of the crystallization process. Ozawa and Kissinger equation were applied to study the non-isothermal crystallization kinetics of PLLA. The results showed that the crystalliazation peaks shift to low direction and peak width increased with increasing of the cooling rate and the molecular weight. The crystallization activation energy are -165.8kJ/mol for the PLLA(M=2.6×10
4
) which Ozawa exponent
m
closing to 3 indicated the crystallization model is heterogeneous nucleation and three-dimensional crystal growth
-82.1kJ/mol and -75.4kJ/mol for the PLLA(M=14.3×10
4
and 19.2×10
4
) which Ozawa exponent m closing to 4 indicated homogeneous nucleation and three-dimensional crystal growth
respectively. The " hinge" model explains the significant difference of the crystallization activation energy of different molecular weight PLLA
and giving the relation between the molecular weight and the crystallization activation of PLLA.
关键词
聚乳酸非等温结晶结晶动力学结晶活化能
Keywords
Polylactic acidNon-isothermal CrystallizationCrystallization KineticsCrystallization activation energy