不同石墨烯-碳纳米管杂化体系对热塑性聚氨酯复合材料力学和自修复性能的增强机制

Enhancement Mechanisms of Mechanical and Self-Healing Properties of Thermoplastic Polyurethane Composites Induced by Different G-CNT Hybridization Systems

采用溶液共混法,设计不同的杂化方案,制备了3种具有不同复合程度的石墨烯(G)和碳纳米管(CNT)三维空间结构材料,并对G-CNT填充的热塑性聚氨酯(TPU)复合材料的力学性能及在微波诱导下的裂纹自修复特性进行了研究.结果表明,G-CNT复合结构能改善增强相与基体间的界面结合及载荷传递,且复合程度越高其对TPU力学增强效果越显著.当采用预复合方法时G-CNT复合程度最高,此时TPU复合材料的拉伸强度比纯TPU提高了37.6%,比G/TPU提高了27.1%.TPU复合材料在微波场的诱导下可实现损伤裂纹的快速修复,然而其修复效率并未随着G-CNT复合程度的增加而升高,当采用超声复合时,G-CNT的复合程度低于预复合法的复合程度,但其修复率却达到最高值(138%).该自修复特性和G-CNT的空间构型及其异质界面与微波之间的耦合机制密切相关.

Three different hybridization degrees of the three dimensional structure of graphene-carbon nanotube（ G-CNT） were prepared by the different experimental schemes. The research on the mechanical property of the thermoplastic polyurethane（ TPU） composites reinforced by this three-dimensional hybrid structure of the G-CNT,and the behavior of self-healing of the damaged TPU composites was carried out. The results show that the three dimensional hybrid structure of G-CNT can effectively promote the load transfer between the reinforcing phase and the TPU matrix,and can improve the mechanical properties of the TPU composites. It also shows that the higher the hybridization degree of G-CNT,the more the enhancement effect will be. When the G-CNT was prepared by the pre-hybridization method,it achieved the highest hybridization degree. And the mechanical properties of the corresponding composite G-CNT/TPU achieved the highest value that equals to 61. 95 MPa. It is about 37. 6% higher than the pure TPU and 27. 10% higher than the G/TPU composite. Meanwhile,it shows that these composites can realize the self-healing of the crack induced by the microwave electromagnetic fields. The tensile strength of these healed samples were even higher than that of their original samples. However,their healing efficiency does not increase as the hybridization degree of G-CNT increased. For example,as for the composite of G-CNT/TPU that prepared by the ultrasonic hybrid method,the hybridization degree of G-CNT is less than that prepared by the pre-hybrid method,but its healing efficiency achieved the highest that equals to 138%. This self-healing characteristic has important relationship with the spatial structure of the 3D G-CNT and the coupling mechanisms between microwave and the heterogeneous interface within G-CNT.