The development of advanced low‐melt polyaryl‐ether‐ketone ( LM ‐ PAEK ) composite adhesive joints with good hygrothermal and chemical resistance

Abstract In this study, a novel high‐power UV irradiation technique was used to activate the bonding surfaces of carbon fiber reinforced low‐melt polyaryl‐ether‐ketone (CF/LM‐PAEK) laminates, followed by bonding with an aerospace adhesive. The effects of hygrothermal aging and aerospace‐solution immersion treatment on the mechanical properties and failure behavior of the CF/LM‐PAEK adhesive joints were investigated. The results indicated that the UV‐irradiation technique efficiently promoted the surface activity of the CF/LM‐PAEK surface. Accordingly, high‐performance CF/LM‐PAEK adhesive joints with a lap‐shear strength of 33.4 MPa were obtained. However, the lap‐shear strength of the joints decreased to 21.2 MPa after a hygrothermal aging treatment. The failure surface analysis revealed that the joint strength reduction was due to the strength degradation at the matrix/carbon fiber interface in the CF/LM‐PAEK composite and the adhesive/composite bonding interface. In contrast, immersing the adhesive joints into aviation kerosene, antifreeze, and hydraulic oil solutions had negligible effects on the lap‐shear strength of the joints. The main failure mechanism was the stripping of the resin matrix at the top surface of the composite substrate, which is identical to the pre‐aging condition. Overall, these findings highlight the importance of surface treatment and environmental factors on the mechanical performance of the CF/LM‐PAEK adhesive joints. Highlights UV irradiation technique was used to treat the surface of the CF/LM‐PAEK. High‐performance adhesively bonded CF/LM‐PAEK joints were obtained. The adhesive joints exhibited good hydrothermal and chemical resistance. The failure mechanisms of the unaged and aged adhesive joints were revealed.