纳米纤维素/聚丁二酸丁二醇酯母粒改性聚乳酸的结晶与力学性能研究

以聚乳酸(PLA)为基体,聚丁二酸丁二醇酯(PBS)为增韧相,纳米纤维素(CNF)为增强相,采用不同的挤出温度,利用双螺杆挤出机熔融共混制备出一系列CNF/PBS母粒改性PLA复合材料。采用扫描电子显微镜、广角X射线衍射仪、差示扫描量热仪、偏光显微镜和万能试验机以及悬臂梁冲击试验机对复合材料的结晶和力学性能进行测试。结果表明:CNF可以起到异相成核的作用,但含量过多易引起团聚;与纯PLA相比,当CNF/PBS复合母粒的添加量为20%时,低温挤出的复合材料的结晶度、冲击强度分别提高了10.66%和141.51%,拉伸强度仅下降14.86%;当CNF/PBS母粒的添加为20%时,低温挤出的PLA基复合材料的结晶度、拉伸强度和冲击强度分别较高温下挤出的复合材料提高了11.61%、3.82%和16.37%。

Crystallization and mechanical property of PLA modified by CNF/PBS master-batch

Polylactic acid(PLA)as matrix material,polybutylene succinate(PBS)as toughening phase,and cellulose nanofiber(CNF)as reinforcing phase,a series of CNF/PBS modified PLA composites were prepared by melt blending using twin-screw extruder with different extrusion temperatures.The crystallization and mechanical properties of the composites were tested by scanning electron microscope(SEM),wide-angle X-ray diffractometer(WAXD),differential scanning calorimeter(DSC),polarized light microscope(POM),universal testing machine and cantilever beam impact testing machine.The results shown that CNF can played the role of heterogeneous nucleation,but excessive content CNF leaded to agglomeration.Compared with pure PLA,when the mass fraction of CNF/PBS composite masterbatch was 20%,the crystallinity and impact strength of the PLA composite at low extrusion temperature were increased by 10.66% and 141.51%,and tensile strength was decreased by 14.86%.When the mass fraction of CNF/PBS composite masterbatch was 20%,the crystallinity,tensile strength and impact strength of CNF/PBS/PLA composites extruded at low temperatures were 11.61%,3.82% and 16.37% higher than those of extruded composites at high temperature respectively.