Effects of Sizing Agents on the Interfacial Heat Resistance of CF/PEKK Composites

The interfacial heat resistance of carbon fiber reinforced polyether ketone ketone (CF/PEKK) composites plays a critical role in their high-temperature applications. In this study, polyetherimide (PEI), polysulfone (PSF) and polyethersulfone (PES) resins were selected as sizing agents for carbon fibers to investigate their effects on the interfacial heat resistance of CF/PEKK composites. Results show that all three sizing resins possess high thermal stability suitable for CF/PEKK composite processing and effectively enhance the interfacial shear strength (IFSS). PEI resin exhibited the best compatibility with the PEKK matrix. The PEI-sized CF/PEKK composites achieved the highest interfacial properties, with an IFSS value of 100.5 MPa, representing a 26.6% improvement over desized composites. Analysis of interfacial heat resistance further revealed that composites modified with 1 wt% PEI retained the highest IFSS of 74.4 MPa at 140°C, which is 31.7% higher than that of desized composites under the same conditions. This enhancement primarily stems from the good compatibility and high heat resistance, which simultaneously improve the interfacial adhesion strength and thermal stability of CF/PEKK composites. These advantages help broaden the application prospects of CF/PEKK composites in high-temperature environments.