聚乳酸/聚氨酯共混物的力学行为与形态研究

摘要

采用双螺杆挤出机制备了一系列聚乳酸(PLA)/热塑性聚氨酯(TPU)共混物,通过万能试验机、悬臂梁冲击试验机和动态力学分析仪对PLA/TPU共混物进行力学性能测试,并对不同拉伸状态下的试样和冲击断面分别进行扫描电子显微镜观察.结果表明,随着TPU含量的增加,PLA/TPU共混物的断裂伸长率和冲击强度显著增大,且储能模量降低,损耗模量升高,其拉伸断面呈现出液滴态—粗纤态—细纤态的演变;当TPU含量达到40％(质量分数,下同)时,PLA/TPU共混物的断裂伸长率和冲击强度分别比纯PLA增加了300％和13.5倍.%A series of poly (lactic acid) (PLA)/thermoplastic polyurethane (TPU) blends were prepared by melt compounding with a twin-screw extruder.A universal testing machine,impact testing machine,dynamic mechanical analyzer (DMA) and scanning electron microscope (SEM) were used to test the tensile property,impact strength,dynamic thermo-mechanical property and morphology of PLA/TPU blends,respectively.The results indicated that the elongation at break,impact strength and loss modulus of PLA/TPU blends increased distinctly with increasing TPU content,and the morphology of fracture surfaces present a change from droplets to thick fibers and thin fibers.Moreover,compared with pure PLA,the elongation at break and impact strength increased by 300 ％ and by a factor of 13.5 for the blend containing 40 wt ％ TPU,respectively.