中文摘要：

采用熔融共混的方法制备微纳纤维素／聚乳酸（PLA）复合膜。用抗张测试机表征了复合膜的机械性能，利用X射线衍射（XRD）、傅立叶红外光谱（FT-IR）、热重分析仪（TGA）对复合膜的结晶度、官能团特征、热稳定性进行表征，扫描电子显微镜（SEM）表征了微纳纤维素在聚乳酸基体中的分散情况以及断面的形貌。结果表明，复合材料的断裂伸长率随着微纳纤维素的质量分数的增加而提高，当纤维素质量分数为4％时，断裂伸长率达到最大值35％，是纯聚乳酸的10．9倍。FT-IR表明复合材料没有新峰出现，说明复合膜中微纳纤维素与聚乳酸为氢键作用，无新官能团产生，达到分子水平的相容。TGA的结果表明复合材料的热稳定性与聚乳酸相比基本没有变化，仍具有良好的热稳定性能。SEM分析表明，200nm左右的微晶纤维素在聚乳酸基体中分散较为均匀，没有团聚现象。

英文摘要：

The casting solution was prepared by blending poly（ lactic acid）（PLA） with micro-nano cellulose to prepare composite film. Tensile testing machine was used to test the mechanical properties. Also, crystallinity, functional groups and thermal stability were analyzed by X-ray diffraction （XRD） , Fourier transform infrared spectroscopy （FT-IR） and thermal gravimetric analysis （ TGA ） , respectively. The dispersion of the micro-nano cellulose in PLA matrix and the cross section of the composite film were characterized by scanning electron microscopy （ SEM ）. The results show that at first, breaking elongation of composite film raises with the increasing of micro-nano cellulose content. The elongation reachs its maximum 35 % , which is 10.9 times of that of the pure PLA when the micro-nano cellulose content is 4 %. In the infrared spectrogram, the composite film has no appearance of other new characteristics peaks. It reveals that there are no new functional groups in the composite film, and the level of molecu- lar compatibility is achieved, which is based on the existence of inter-molecular hydrogen bond association between PLA and micro-nano cellulose. TGA shows that, compared with the PLA film, thermal stability of the composite hasn＇t changed, showing good thermal stability. In the SEM, the micro-nano cellulose of ca. 200 nm distributed evenly in the matrix without agglomerating phenomenon.