Enhanced mechanical property of continuous carbon fiber/polyamide thermoplastic composites by combinational treatments of carbon fiber fabric

To fabricate continuous carbon fiber (CF)/polyamide (PA 6) thermoplastic composites with high strength and stiffness, combinational treatments of liquid phase oxidation, coupling agent, and coating were adopted to improve the surface activity of CF fabric and interfacial bonding with PA 6 matrix. The mechanical properties, dynamic thermomechanical properties, microstructure, and hydrothermal aging behavior of the CF/PA 6 composites were studied. The XPS results showed the N, O, and Si elements as well as the C–O, CO, and C–Si groups were significantly increased on the CF surface, indicating the improvement of chemical activity and KH550 effectively grafted. The tensile strength significantly increased from 396 MPa to 480 MPa, by 21.2%, and Young's modulus increased from 38.6 GPa to 47.9 GPa, by 24.1%, respectively. The result of the damp heat aging test in 240 h showed the retention rate of flexural strength and ILSS were 66% and 67%, respectively.