Constructing “nunchaku-like” multi-stage gradient interface via covalently grafting rigid-flexible-rigid structures onto carbon fibers: An effect strategy to improve interfacial properties of composites

A multi-scale “nunchaku-like” rigid-flexible-rigid structure was constructed on the CF surface using carbon nanotubes (CNTs) and polyether amines (PEA) to improve the interfacial properties of carbon fiber (CF) reinforced polymer composites . The multi-scale rigid-flexible-rigid structure not only enhanced the chemical bonding, mechanical engagement and wettability , but also balanced the modulus of the fibers and resin to achieve best match for less stress concentration. As a consequence, IFSS , ILSS and TFBT strength increased by 73.4%, 65.4% and 137.0% compared to the original composites. In addition, the composites failure behavior and the interfacial strengthening mechanism were investigated in detail. This work proposed a novel and promising strategy for the preparation of high-performance CF composite from the perspective of interfacial structure design.