Improvement adhesion durability of epoxy adhesive for steel/carbon fiber-reinforced polymer adhesive joint using imidazole-treated halloysite nanotube

Abstract

Surface treatment is essential for enhancing adhesion durability and minimizing substrate damage in hybrid structural materials. This study focuses on developing a hybrid adhesive lap joint by incorporating halloysite nanotube (HNT) with imidazole-functionalized surfaces (IM-HNT) into epoxy adhesives to improve adhesion performance and thermal shock resistance. The surface treatment of HNT with imidazole (IM) introduced a curing catalyst effect, reducing activation energy by 50% and accelerating curing time by 90%, as confirmed by Kissinger’s plot and permittivity measurements. The optimized IM-HNT content improved thermal stability by controlling thermal expansion and enhanced mechanical properties, achieving a 15% increase in tensile strength and a 50% enhancement in fracture toughness. The adhesion performance of steel/carbon fiber-reinforced polymer (CFRP) hybrid joints was evaluated through single-lap shear tests, demonstrating a 25% improvement in shear strength. Adhesion durability was tested under cyclic thermal shock conditions, showing a 30% increase as IM-HNT content increased. Finite element analysis (FEA) revealed reduced residual stress at the adhesive interface, supporting the enhanced thermal and mechanical robustness. This study highlights the potential of surface-treated halloysite nanotubes in hybrid adhesive lap joints to significantly improve adhesion durability and thermal shock resistance, addressing critical requirements for hybrid structural materials.