三臂聚乳酸对线型聚乳酸性能的影响

Influence of Three-armed PLLA on Properties of Liner PLLA

通过将三臂聚乳酸添加到线型聚乳酸的内部，大幅提高了线型聚乳酸的冲击强度，当三臂聚乳酸质量分数达到2％～8％时，冲击强度达到线型聚乳酸的2倍左右；通过偏光显微镜观察，可以看到三臂聚乳酸提高了线型聚乳酸的结晶成核速度，使其晶体数量增多，形态变小；而通过等温结晶试验表明其结晶速度提高，结晶是以异相成核的三维生长方式进行的；流变学试验表明，加入三臂聚乳酸有效地降低了体系的复数黏度，当三臂聚乳酸质量分数达到8％时候，在频率为1～10rad／s时，其数值仅为线型聚乳酸的60％左右，这种变化将提高其加工成型能力。

Three-armed poly （L-lactide acid） （PLLA） was mixed into the linear PLLA matrix. It is found that the addition of three-armed PLLA could increase the quantity of the crystal nucleus, and finally increase the crystal amount and reduce their diameter. The addition of three-armed PLLA could increase the impact strength of the mixture, when the three-armed PLLA content reaches 2wt% - 8wt%, the impact strength could increase to the twice value of the pure linear PLLA. The isothermal crystallization experiment results show that the mixture has higher crystalline rate than the pure linear PLLA, and the mode of the crystal growth is the three-dimension growth induced from the heterogeneous nucleation. Furthermore the addition of three-armed PLLA could decrease the complex viscosity of the system. When the three-armed PLLA dosage reaches 8wt%, the complex viscosity of the blend could reduce to about 70% of the linear PLLA.