Additively manufactured short carbon fiber reinforced polyetheretherketone by coating polyetherimide at the interface using fused filament fabrication

The poor interfacial interactions and bonding between short carbon fibers (CFs) and polyetheretherketone (PEEK) resin matrix is a great challenge to manufacture high-performance 3D printed CF/PEEK composites. Therefore, this paper presents a research focusing on the compatibility of CFs and PEEK. We propose an effective method to graft polyetherimide (PEI) onto activated CFs, then, composite filaments with modified fiber contents of 2.5%, 5%, 7.5% and 10% were prepared using fused filament fabrication (FFF). The chemical structures and surface morphologies of modified CFs were characterized, and the rougher surfaces with more polar groups can enhance the wettability of these CFs, which is improve the physical adhesion with PEEK. The thermal properties and mechanical properties of CF/PEEK composites within different carbon fiber contents were investigated. The results show that the tensile strength, flexural strength and interlaminar shear strength (ILSS) of 3D printed 5 wt% PEI@CF/PEEK parts were greatly improved by 40.85% (92.4 MPa), 35.70% (151.3 MPa) and 130.22% (26.59 MPa), respectively, which caused by the improvement of interfacial adhesion between CFs and PEEK resin. The results suggested that this modification is an effective approach to coating PEI on the surface of carbon fiber and enhance the mechanical properties of 3D printed PEEK composites. This method provides new insights for fabricating high-performance 3D printed thermoplastic composites.