ENHANCING BONDING PERFORMANCE IN CF/EPOXY COMPOSITES THROUGH CNT-REINFORCED ADHESIVE AND PROCESS OPTIMIZATION

Thermosetting composites are widely used across various industries because of their excellent mechanical properties, thermal stability, and chemical resistance. These materials are commonly provided as standard-thickness panels, stored until needed, and subsequently joined or assembled to meet specific thickness and shape requirements. This study employed a two-step bonding process to improve adhesive performance in CF/Epoxy composites. First, the temperature-dependent viscosity of toughened epoxy was used to disperse through ultrasonic mixing, enhancing the bonding strength and mechanical properties. A bonding performance test conducted under ASTM D5868 showed that CNT reinforcement improved the bonding properties. However, high-temperature curing sometimes causes adhesive leakage, degrading the bonding quality. To improve this issue, a pre-impregnated carbon fiber sheet was developed to stabilize the adhesive layer and prevent leakage. This step further enhanced the bonding reliability and interfacial uniformity. For neat, the maximum load increased from 5.66[Formula: see text]kN to 7.52[Formula: see text]kN, reflecting a 33% enhancement—similarly, the maximum load for 0.1 wt.% CNT improved from 6.83[Formula: see text]kN to 7.85[Formula: see text]kN (15%). Failure behavior was analyzed through OM and SEM. This study presents a novel bonding strategy combining CNT-reinforced toughened epoxy with pre-impregnated sheets, thereby addressing both conventional adhesive limitations.