Improvement of Fracture Toughness of Epoxy Nanocomposites Through In‐Plane Crack Propagation Resistance Offered by Wet Ball‐Milled Graphene Oxide

ABSTRACT Fascinating features of 2D graphene oxide (GO) have very high potential to enhance the mechanical performance and fracture toughness of epoxy composites after successful dispersion in the epoxy matrix. The dispersion of GO in a highly viscous epoxy matrix was achieved by lateral exfoliation and longitudinal size reduction of graphene sheets. GO was synthesized via an improved Hummer's method, exfoliated through dual‐mode ultrasonication for 20, 30, and 60 min, and reduced to nanoscale (~217 to 227 nm) using high‐energy wet ball milling for 9 h. The synthesized GO and BGO were characterized using XRD, FT‐IR, Raman spectroscopy, FESEM, and TGA to confirm crystal structure, functional groups, defect density, surface morphology, and thermal stability respectively. It was observed that even at higher filler loadings of 1 wt.% of GO and BGO exfoliated for 60 min (GO60@1% and BGO60@1%), the resulting nanocomposites showed a substantial improvement in tensile strength by 39.92% and 41.91%, respectively, and modulus by 6.92% and 12.90%, respectively compared to the NE. Whereas, incorporation of GO60@1% and BGO60@1% into epoxy matrix significantly enhanced fracture toughness ( K IC ) by ~72% and ~140% respectively and the fracture energy ( G IC ) by ~322% and ~356%, respectively with respect to NE. The enhancement is attributed to the superior dispersibility of BGO, which facilitates strong and consistent interfacial interactions with the epoxy matrix, thereby improving the material's resistance to fracture. The exfoliation of GO through ball milling can be a suitable method for industries to prepare graphene‐based nanocomposites with significantly high tensile and fracture properties.