Polyetherketoneketone/carbon fiber composites with an amorphous interface prepared by solution impregnation

Interfacial adhesion between carbon fibers (CF) and polyetherketoneketone (PEKK) is a key factor that affects the mechanical performances of their composites. It is therefore of great importance to impregnate the CF bundles with PEKK as efficiently as possible. We report that PEKK with a good dispersion in a mixed solution of 4-chlorophenol and 1,2-dichloroethane can be introduced onto CF surfaces by solution impregnation and curing at 280, 320, 340 and 360 °C. The excellent wettability or infiltration of the PEKK solution guarantees a full covering and its tight binding to CFs, making it possible to evaluate the interfacial shear strength (IFSS) with the microdroplet method. The interior of the CF bundles is completely and uniformly filled with PEKK by solution impregnation, leading to a high interlaminar shear strength (ILSS). The maximum IFSS and ILSS reached 107.8 and 99.3 MPa, respectively. Such superior shear properties are ascribed to the formation of amorphous PEKK in the small spaces between CFs.