Enhancing microfibrillated cellulose reinforcing efficiency in epoxy composites by graphene oxide crosslinking

Microfibrillated cellulose (MFC) has the potential to be used as an alternate reinforcement to glass fibers. However, glass fiber reinforced epoxy composites at usual operating temperatures (below Tg) are still superior to MFC infused epoxy composites. In this work, MFC mats with variable amounts of graphene oxide (GO) crosslinking were prepared using epichlorohydrin. Crosslinked MFC/GO epoxy composites with constant fiber content and different GO loadings were fabricated by impregnation of the freeze-dried crosslinked MFC/GO mats with the epoxy/hardener mixture followed by compression molding. Composites with 15 vol% MFC and 2 wt% GO crosslinking exhibit a storage modulus in the glassy state (40 degrees C) of 6.5 GPa, which surpasses the storage modulus of glass fiber/epoxy composite with similar fiber volume content (6.2 GPa at 40 degrees C). Thus, with a small amount of GO crosslinking, MFC was shown to possess superior modulus and lower weight when compared to glass fiber composites at similar fiber volume content. Graphic abstract