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

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 14 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.