Preparation of PEK-C-toughened epoxy structural adhesive for bonding CF/PEEK composites

Abstract

In this paper, an epoxy structural adhesive was fabricated by using the high-performance thermoplastic engineering plastic phenolphthalein-based polyaryletherketone (PEK-C) as tougheners, and 4,4′-diaminodiphenylsulfone (DDS) and 4,4-diaminodiphenylmethane (DDM) as the curing agents. The effect of PEK-C on the mechanical properties, microstructure, and adhesive properties of the modified epoxy resin system was investigated. Epoxy structural adhesive with 20 phr PEK-C exhibited excellent bonding performance and thermal stability. The PEK-C toughened adhesive presented high shear strength of 31.6 MPa and 27.6 MPa at 120°C and 150°C, respectively. The PEK-C toughened epoxy structural adhesive was then used to bond CF/PEEK composites, and the effects on the bonding properties of CF/PEEK were investigated. By the combined treatment of sandpaper grinding and corona discharge (80 mesh sandpaper sanding + corona treatment for 30 s), the shear strength of the composite joints is increased to 18.73 MPa. And the shear strength retention rate of the joint was 99.8%. The strategy can be used to fabricate sandwich structures with CF/PEEK as the skin with excellent performance. Therefore, PEK-C toughened modified epoxy resin is conducive to the enhancement of adhesive properties and has a better performance for the bonding of CF/PEEK materials.