Water‐immersion effect on radial crack initiation behavior in a fiber‐bundle‐reinforced epoxy cylinder with graphene in the interfacial region

Abstract

The long‐term durability of polymer composites serviced under moist, high‐temperature conditions is a major concern in many industries. As an attempt, we filled 0.3 wt % graphene in a fiber–matrix interfacial region between glass fibers, carbon fibers, glass–carbon hybrid fibers, and epoxy resin to enhance the mechanical performance of the composites under water‐immersion conditions. The mass increment was recorded periodically while the specimens were immersed in 25 and 70°C water. Axial compression tests were carried out to investigate the initiation behavior of the interfacial radial microcracks after immersion. The results show that the equilibrium moisture content and permeability of the graphene‐filled interfaces were larger than that of the virgin specimens. The interfacial radial crack initial stress decreased sharply after immersion; however, the addition of graphene in the fiber–matrix interface help to decrease this tendency in 70°C water. The observed rough surfaces of the graphene‐coated fibers after breakage in the compression tests verified the feasibility of this method. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47080.