Interfacial performance and build orientation of 3D‐printed poly(ether‐ketone‐ketone) reinforced by continuous carbon fiber

Abstract Continuous fiber reinforced thermoplastic composites (CFRTPCs) prepared by fused deposition modeling (FDM) have gained great attention for the benefit of preparing products without molds. However, unexpected debonding and defects are derived from insufficient impregnation between fiber and matrix in 3D‐printed samples, resulting in weak interfacial performance. In this work, a polyetherimide (PEI) sizing agent was used to improve the fiber‐matrix interfaces, and the interlaminar shear strength (ILSS) of the continuous carbon fiber reinforced poly(ether‐ketone‐ketone) composites was increased to 27.1 MPa, 12.4% higher than that of unmodified composite. Meanwhile, the performance of CFRTPCs is affected by process parameters in FDM. Build orientation of FDM was discussed and PEI weakened the anisotropy of samples' mechanical properties because the performance variation caused by build orientation decreased from 86.8% to 65.2%, which may be beneficial for the forming freedom of in situ impregnated FDM. The addition of PEI makes sense to apply in situ impregnated FDM in high‐tech fields. Highlights CCF/PEKK composites were prepared by in situ impregnated FDM. ILSS of flat‐oriented CCF/PEKK was 86.8% higher than that of on‐edge. 5 wt% PEI sizing agent promoted adhesion of CCF and PEKK to obtain the best mechanical properties. PEI weakened the anisotropy of samples' mechanical properties, which was conducive to forming freedom.