Size effect of graphene nanoplatelets on the morphology and mechanical behavior of glass fiber/epoxy composites

We investigated the effect of graphene nanoplatelets (GnPs) with two different lateral dimensions on the morphology, flexural, and thermo-mechanical properties of multiscale GnPs/glass fiber/epoxy composites. First, 3 and 5 wt% of GnP-C750 (<1 µm in diameter) and GnP-5 (5 µm in diameter) were individually integrated into epoxy suspension through a combination of calendaring and sonication processes. The GnPs/glass fiber/epoxy composites were then fabricated by incorporating glass fibers into the GnPs/epoxy mixture. Results showed that the flexural modulus of the GnPs/glass fiber/epoxy composites was improved by 11.5 and 26.3 % with the addition of 5 wt% GnP-C750 and GnP-5, respectively. At the same filler content, the storage modulus of the glass/epoxy composites incorporated with GnP-C750 and GnP-5 at 30 °C was enhanced by 10.2 and 28.2 %, respectively. The flexural strength of the 3 wt% GnP-5-reinforced glass fiber/epoxy composite is 16.2 % higher than that of the glass fiber/epoxy composite. The dispersion results of GnPs in the composites and the interfacial interactions between fibers and modified matrix were evaluated by scanning electron microscopy.