Improving interface property of epoxy resin composite via in‐situ growth of ZIF‐8 onto carbon fiber with branched polyethyleneimine

Abstract The interface property of carbon fiber/matrix materials is a key factor influencing the service life of composites. In this paper, our group facilely in‐situ grew zeolitic imidazolate framework‐8 (ZIF‐8) onto the carbon fiber (CF) surface by using branched polyethyleneimine (BPEI) as coupling agent to simultaneously enhance the interface and mechanical performances of CF/epoxy composite. The successful growth of ZIF‐8 nanocrystals onto carbon fiber was confirmed by FT‐IR, XPS, TGA, XRD, Raman, and SEM. After growth of ZIF‐8, the surface morphology for CF grafted with ZIF‐8 (CF‐ZIF‐8) was greatly changed and the surface energy for modified carbon fiber increased from 28.7 mN/m for the untreated CF to 55.8 mN/m. As a result, the interfacial shear strength (IFSS) of CF‐ZIF‐8/epoxy composite enhanced by 103.4%, indicating a significant improvement of interface property of composite. Moreover, the interlaminar shear strength (ILSS) and bending strength also have 37.8% and 23.3% improvement because of the synergistic effect of BPEI and ZIF‐8 compared to the untreated CF/epoxy composite. This work furnishes a facile and efficient strategy for developing high‐performing structural composite materials with excellent interface property. Highlights ZIF‐8 was in‐situ grown on CF to improve the interface property of composite. Significant improvements on IFSS, ILSS, and bending strength. The mechanism for improving the performances of composite was proposed.