PUR-T协同CNF对PLA结晶及力学性能的影响

Effects of PUR-T and CNF on Crystallization and Mechanical Properties of PLA

以热塑性聚氨酯(PUR-T)为增韧相,纳米纤维素(CNF)为增强相,利用双螺杆挤出机制备一系列PUR-T/CNF改性聚乳酸(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、万能试验机和悬臂梁冲击试验机对复合材料的断面形貌、结晶和力学性能进行测试。结果表明,PUR-T对PLA的结晶有着抑制作用,CNF对PLA结晶成核有着促进作用,且都对PLA的晶型没有影响。相比于PLA,当PLA/PUR-T质量比为90/10时,PLA/PUR-T复合材料的结晶度、拉伸强度和拉伸弹性模量分别降低了3.73%,11.0%,10.0%,缺口冲击强度和断裂伸长率分别提高了19.1%和3.1%,PUR-T/CNF质量分数为10%的PLA/PUR-T/CNF复合材料的拉伸强度、缺口冲击强度和断裂伸长率分别增加了3.5%,41.2%,4.18%,结晶度和拉伸弹性模量分别降低了0.98%和35.7%。

Thermoplastic polyurethane(PUR-T)as the toughening phase,nanocellulose(CNF)as the reinforcing phase,a series of PUR-T/CNF modified PLA composites were prepared by twin-screw extruder.The fracture morphology,crystallization and mechanical properties of the composites were tested by scanning electron microscope(SEM),wide angel X-ray diffractometer(WAXD),differential scanning calorimeter(DSC),polarizing microscope(POM),universal testing machine and cantilever beam impact testing machine.The results show that PUR-T inhibit the crystallization of PLA,and CNF promote the crystallization nucleation of PLA,and both has no effect on the crystal form of PLA.Compared with pure PLA,when the PLA/PUR-T mass ratio is 90/10,the crystallinity,tensile strength and tensile elastic modulus of PLA/PUR-T composite decrease by 3.73%,11.0%and 10.0%,respectively,while notched impact strength and elongation at break increase by 19.1%and 3.1%,respectively.The tensile strength,notched impact strength and elongation at break of PLA/PUR-T/CNF composites with 10%PUR-T/CNF mass fraction increase by 3.5%,41.2%and 4.18%,respectively,and the crystallinity and tensile elastic modulus decrease by 0.98%and 35.7%,respectively.