Preparation and Characterzation of High‐Thermal‐Stability PI / PEKK Composite Films

This study successfully prepared high‐performance polyimide/polyetherketone ketone (PI/PEKK) composite films through atmospheric pressure plasma modification combined with solution coating technology, with the aim of improving the thermal stability and mechanical properties of aviation cable insulation materials. Firstly, a PEKK multi‐scale water‐based dispersion scraping process was developed, and 380°C was determined to be the optimal sintering temperature. Composite film performance tests show that a PEKK coating with a concentration of 10 wt% can form a uniform and continuous coating on the PI film surface, and the PI/PEKK composite film exhibits excellent comprehensive performance. In terms of thermal stability, the glass transition temperature reaches 292°C, which is a significant improvement over the pristine PI film (272.5°C). The initial decomposition temperature (T 5% ) exceeds 520°C, and the carbon residue at 800°C remains above 57%. In terms of dielectric properties, the dielectric constant in the 40 Hz low frequency range has been increased to 3.49, while maintaining low dielectric loss. In terms of mechanical properties, the tensile strength reached 293.28 MPa, and the peel strength was as high as 5.12 N/cm.