Enhanced Mode I Fracture Toughness in Composite Joints: Synergistic Effects of CNT-Reinforced Epoxy Adhesives

High-performance adhesives are essential for creating durable, long-lasting bonds in various applications. This study explores the novel use of carbon nanotubes (CNTs) to enhance the fracture toughness of polymer adhesives, explicitly focusing on their effect on the Mode I fracture toughness of glass fibre-reinforced composite bonded joints. Unlike traditional research, this work investigates CNT-reinforced diglycidyl ether of bisphenol A (DGEBA) epoxy adhesives applied to double cantilever beam (DCB) joints. CNTs were incorporated at varying mass fractions (1, 2 and 5 wt.%), and the findings demonstrate that 1 wt.% CNTs yielded the most significant improvement, doubling fracture toughness compared to unreinforced adhesive (NE) due to optimal dispersion and strong matrix interaction. Numerical simulations supported the experimental results, confirming the effectiveness of CNTs in modifying cohesive and interfacial failure mechanisms. This study highlights a promising and less-explored avenue for developing advanced composite adhesives with superior mechanical performance.