Bio-composites made of polylactic acid (PLA) matrix reinforced with cellulose fibers (CF) were prepared using a twin-screw extruder and injection molding. The CFs were coated with epoxy-based surface treatment agents. Accelerated degradation tests were carried out on these PLA/CF composites at high temperatures (60 °C) or at constant temperature and constant humidity (60 °C/70% RH), and the higher-order structure changes and degradation characteristics of the molded products were evaluated. In the accelerated degradation test at 60 °C, the thermal and mechanical properties of PLA/CF composites showed no degradation, whereas at 60 °C and 70% RH, the melting point decreased ca. 25 °C and the storage modulus with increasing elapsed time decreased more than 50%. However, the thermal and mechanical properties of the PLA/CF composites treated with low-molecular-weight epoxy did not degrade, even at the high humidity of 70% RH. These results strongly suggest that the surface treatment agent not only improves interfacial adhesion between CF and PLA but also plays an important role in inhibiting degradation of the PLA matrix.

使用双螺杆挤出机和注模法制备由纤维素纤维（CF）增强的聚乳酸（PLA）基质制成的生物复合材料。CF涂有基于环氧树脂的表面处理剂。在高温（60°C）或在恒定温度和恒定湿度（60°C / 70％RH）下对这些PLA / CF复合材料进行了加速降解测试，并且成型品的高阶结构变化和降解特性产品进行了评估。在60°C的加速降解试验中，PLA / CF复合材料的热性能和机械性能未显示降解，而在60°C和70％RH的情况下，熔点降低。25°C时，储能模量随经过时间的增加而下降超过50％。然而，即使在70％RH的高湿度下，用低分子量环氧树脂处理的PLA / CF复合材料的热和机械性能也不会降低。这些结果强烈表明，表面处理剂不仅改善了CF与PLA之间的界面粘合力，而且在抑制PLA基质的降解中起着重要的作用。