Enhancement on the mechanical properties of 3D printing PEI composites via high thermal processing and fiber reinforcing

Abstract Polyetherimide (PEI) is a high‐performance material that maintains good properties at high temperature. Combining PEI with 3D printing is helpful to broaden the application of PEI, but the printed PEI parts have poor mechanical properties due to its interlayer porous structure. Herein, high thermal processing (cavity and platform temperature) is utilized to improve the bonding of PEI filaments during 3D printing. After optimizing, the mechanical properties of printed PEI parts can reach to the performance of injected PEI. Moreover, carbon fiber (CF) is used to further enhance the thermal and mechanical properties of PEI. The results show that the mechanical enhancement of short length CF (0.15 mm) is less effective than the longer CF (3 mm‐CF). After the CF oxidation treatment, the tensile strength of printed PEI is increased by nearly 6.07% compared to the untreated CF/PEI. The work provides a novel approach for developing 3D printed CF/PEI composites for the further application.