Abstract: PLLA/reactable nano-SiO2 (RNS) composites were prepared via melting blending. The isothermal crystallization behavior of PLLA and its composites was studied with differential scanning calorimetry(DSC) and the effect of RNS was explored. The crystallization Kinetics under isothermal conditions was described by using Avrami equation. It showed that RNS had the function of heterogeneous nucleation to PLLA matrix. With increasing RNS content, the crystallization rate K of PLLA matrix was increased and the half-time crystallization t1/2 decreased, while the Avrami exponent n had no significant change, which indicated that RNS hadn't changed the nucleation mechanism of PLLA. In addition, Arrhenius and Lauritzen-Hoffmann equations were employed to estimate the activation energy ΔE, the nucleation parameter Kg, and the end surface energies σe. It was found that the activation energy of the composites was smaller than that of the pure PLLA. The values of Kg and σe for the composites have increased slightly compared with pure PLLA.

Key words: poly(l-lactide), nano-SiO2, composite, isothermal crystallization kinetics