Comparative study on effects of epoxy sizing involving ZrO2 and GO on interfacial shear strength of carbon fiber/epoxy composites through one and two steps dipping routes

Abstract

GO and ZrO2 were added into the epoxy sizing agents of carbon fibers via one-step (CF/ZrO2-GO) and two-step (CF/ZrO2/GO) dipping approaches to create different particle arrangements on fiber surface. Synergistic strengthening effects of GO and ZrO2, as well as the effects of their arrangement, on interfacial shear strength (IFSS) of composites were discussed and compared. IFSS of CF/ZrO2/GO is 98.9 MPa, respectively 41.6%, 28.3% and 18.1% exceeding those of untreated fibers, oxidized fibers and CF/ZrO2-GO. IFSS enhancement of CF/ZrO2/GO is mainly ascribed to its surface inside ZrO2/outside GO structure, which is more effective to deflect cracks and dissipate energy. Moreover, interphase with ladder-shapped modulus transition, interfacial synergetic interactions of covalent bonding, hydrogen bonding and π-π stacking, and higher surface energy also contribute its improvement in IFSS. Therefore, the design of fiber surface with appropriate structure via regulation of particle arrangement opens a promising door for obtaining high-performance composites.