Improvement on strength and toughness for CFRPs by construction of novel “soft-rigid” interface layer

Carbon Fiber-Reinforced Polymers (CFRPs) with higher strength and toughness are indispensable to meet the demand from the rapid advancing industry sectors such as automotive, aviation, and aerospace. A novel “soft-rigid” interface layer was designed via a mild and facile self-assembly strategy to achieve simultaneous improvement for strength and toughness. The positively charged polyethyleneimine (PEI), and negatively charged nano-complex composed of metal-organic framework (UIO-66) and graphene oxide (GO) were assembled on carbon fibers (CFs) through electrostatic interaction. The results shown that the roughness and wettability on the fiber surface were significantly improved by fiber surface modifications. Compared with the composite using pristine CFs as reinforcement, the interfacial shear strength (IFSS) and interlaminar shear strength (ILSS) of the composite with the “soft-rigid” interface phase were improved by 42.12% and 23.07%, respectively. Besides, the debonding and fracture surface of CFRPs after treatment showed improved interface performance. Moreover, the impact toughness of the composite was improved from 60.24 kJ/m² to 89.38 kJ/m².