Poly(p-phenylene benzobisoxazole) Fiber/Epoxy Composites Reinforced with Carbon Nanotubes and Graphene Oxide for Enhanced Interfacial Adhesion and Mechanical Strength

Herein, CNT and GO were used to construct the multiscale-reinforced interphase of the PBO fiber composite for exploring their action in the interfacial adhesion and overall mechanical performance. Compared to the grafting CNT or GO, the cografting of CNT/GO shows better interfacial regulation including increased surface wettability of fiber, enhanced interfacial adhesion, and improved failure resistance of the interfacial region. The interface structure of GO@CNT endows the composites with significantly improved interfacial adhesion. The IFSS and ILSS increased by 20.75 (or 31.42)% and 32.85 (or 51.64)%, respectively, compared to the interphase of CNT (or GO). The reinforcing effect of CNT/GO also leads to the improvement in mechanical features, interfacial load transfer, local stress elimination, and crack propagating inhibition of the interphase. The impact strength of PBO–GO@CNT composite increased from 67.25 to 106.78 kJ/m2. The strategy of interfacial engineering developed by our study will play a crucial role in the field of structural materials, flexible sensors, supercapacitors, catalysts, and energy conversion and storage materials.