Energy induced carbon nanotube rapidly assemble variable interweaving networks at the carbon fiber interface

Regulating carbon fiber with carbon nanotubes (CNTs) is important to improve the interface mechanical properties of composite materials. Therefore, a “thermotropic flash assembly (TFA)” process for the synthesis of CNTs in liquid phase is proposed. This work achieves the continuous and controllable formation of a micro-nano interweaving network of CNTs, with predictions made from a thermal perspective through enhancements to the process. Firstly, 12 working conditions and a large number of sample data are established by microcontrolling carbon fiber energy, and the growth thickness of CNTs is predicted by self-learning algorithm. Secondly, the “liquid-solid-solid” thermotropic growth of CNTs is proposed for the first time, which is different from the existing “gas-liquid-solid” and “gas-solid-solid” growth mechanisms of CNTs. Theoretical deductions and calculations are made for the interfacial temperature, exothermic, and endothermic energies during the growth process, which leads to the determination of a thermal growth space radius of 2.4 μm at the interface. Finally, it is found that the shear strength is increased by at least 27.7 %, although some tensile strength is sacrificed. This work not only points out the direction for low-cost, large-scale and customized control of interface properties, but also lays a theoretical foundation for exploring the growth mechanism of CNTs in an open environment at low temperature.