Improving Strength and Stiffness of GFRP Adhesive Joint Using Dual Reinforcement and Silane Functionalization

ABSTRACT The present study investigates the effect of octadecyl‐trichlorosilane functionalization of chopped glass strand mat (CGSM), Graphene nano particles (GNP) reinforcement on shear and vibration behavior of glass fiber–reinforced polymer (GFRP) composite single lap joints (SLJs) fabricated through co‐cure approach. The experimental results revealed that both the type of reinforcement and the surface functionalization play a crucial role in enhancing the shear strength of the SLJ. Specifically, the incorporation of functionalized graphene nano particles (FGNP) and functionalized chopped glass strand mat (FCGSM) reinforcement has increased the load carrying behavior of composite joint under loading. It shows significant improvement in shear strength enhancement by 97.06%, 77.33%, 67.9%, 5.96%, 31.66% and 8.19% compared to Plain, CGSM, CGSM+GNP, FGNP, FCGSM and FGNP+CGSM respectively. This enhancement has been attributed to functionalization of reinforcements that improve the interfacial bonding behavior between adhesive and adherends. Field Emission Scanning Electron Microscopy analysis has confirmed that CGSM reinforcement without surface modification has exhibited smooth surfaces with poor adhesion, while the incorporation of non‐functionalized GNP has led to agglomeration and crack propagation. Failure analysis demonstrated that functionalized dual‐scale reinforcements effectively suppress the agglomeration, alter fracture morphology, and significantly improve the structural integrity and durability of adhesive joints. Vibration analysis revealed that FGNP with CGSM reinforced SLJ has achieved the highest fundamental natural frequency.