苎麻纤维表面改性对聚乳酸结晶及拉伸性能的影响

Effect of surface treatment of ramie fiber on crystallization behavior and tensile properties of poly(lactic acid)

采用偏光显微镜(PLM)、差示扫描量热仪(DSC)、扫描电子显微镜(SEM)等探究了苎麻纤维(RF)表面处理参数对模压聚乳酸(PLA)/RF复合材料结晶行为和拉伸性能的影响。结果表明,碱处理参数影响RF诱导PLA的结晶行为,碱处理时间为3 h时RF促进PLA结晶,降低冷结晶温度(Tc),提高相对结晶度,增加横晶致密程度;碱处理时间为6 h时,RF对PLA结晶有阻碍作用。Mo方法量化分析PLA非等温结晶动力学研究结果表明,植物纤维表面形貌的变化不改变PLA的结晶机制。拉伸性能测试结果表明,碱处理时间为6 h时增强和增韧效果最佳,PLA/RF复合材料的拉伸强度和断裂伸长率分别提高了19.6%和23.9%。

The effect of surface treatment parameters of ramie fibers(RF)on the crystallization behavior and tensile properties of molded polylactic acid(PLA)/RF composites were investigated using polarized light microscopy,differential scanning calorimetry,and scanning electron microscopy. The results indicated that the crystallization behavior of PLA was greatly affected by the alkaline treatment time of RF surface. After the RF surface was treated for 3 h,PLA presented an increase in transcrystalline density. Its cold-crystallization temperature was reduced,but its relative degree of crystallinity was improved. When the treatment time was increased to 6 h,the crystallization of PLA was hindered by RF. The Mo’s method was adopted to study the non-isothermal crystallization kinetics of PLA quantitatively. The results indicated that the change of the fiber morphology did not cause a change in the crystallization mechanism of PLA. The tensile test results showed that the optimal strengthening and toughening effects were achieved for the PLA/RF composites at an alkaline treatment time of 6 h. In this case,the composites exhibited an increase in tensile strength and elongation by 19. 6 % and 23. 9 %,respectively.