Synergistic Effect on Mechanical Properties of Glass Fiber Reinforced Epoxy Composites by Simultaneous Interfacial Modification Using Graphene Oxide and Matrix Modification With Multiwalled Carbon Nanotubes

A novel hierarchical epoxy/glass fiber (GF) composite was developed through a dual‐modification strategy combining interfacial modification using graphene oxide (GO) and matrix reinforcement with multiwalled carbon nanotubes (MWCNTs). GO nanoparticles were grafted onto oxidized GFs via a one‐step dip coating process utilizing a silanization technique, while 0.5 wt% MWCNTs were uniformly dispersed within the epoxy matrix. The resulting GO‐functionalized GFs and MWCNT‐reinforced epoxy matrix were integrated using a conventional hand layup technique. This simultaneous interfacial and matrix modification led to a significant improvement in the composite's mechanical properties. The optimized epoxy/GF‐GO/MWCNTs composites exhibited a maximum tensile strength of 176 MPa, flexural strength of 281 MPa, and mode‐II fracture toughness of 1.684 N/mm, outperforming the baseline epoxy/GF composites, which showed values of 107 MPa, 198 MPa, and 1.267 N/mm, respectively. The enhanced performance is attributed to the synergistic interaction between the improved fiber–matrix interfacial bonding and the effective stress transfer enabled by the MWCNTs within the epoxy matrix. These results demonstrate the potential of this integrated modification approach in developing high‐performance structural composites with superior mechanical and in‐plane shear properties.