Functional-group-mediated interfacial engineering of BF/PA66 composites for enhanced interfacial adhesion

To meet the demand for lightweight, high-performance and green sustainable materials, basalt fiber-reinforced polyamide 66 (BF/PA66) composites show great application potential in aerospace and automobile manufacturing. However, poor interfacial compatibility between basalt fibers (BF) and PA66 matrix limits their comprehensive performance. In this study, BF surfaces were modified with amino (KH-550), epoxy (KH-560) and mercapto (KH-590) silane coupling agents to enhance interfacial bonding. Systematic tests were conducted on composites with 15 wt% fiber content. The results showed that all silane coupling agents were successfully grafted onto BF surfaces via Si-O-Si covalent bonds, improving fiber surface roughness and reactivity. KH-550 modification achieved the optimal performance: tensile, flexural and impact strengths increased by 25.12%, 45.57% and 46.08% respectively compared with pure PA66, with the strongest interfacial binding energy (−7.84 kcal/mol). Additionally, KH-550 reduced water absorption by 38.89% and improved thermal stability. This study provides an efficient and eco-friendly method for interfacial regulation of BF/PA66 composites.