Gradient Impregnation and Temperature‐Controlled Quenching for Low‐Porosity, High‐Strength Carbon Fiber Reinforced Poly(Ether Ketone Ketone) Composites

ABSTRACT

The increasing demand for lightweight, high‐strength carbon fiber reinforced thermoplastic composites in the aerospace sector has identified poly(ether ketone ketone) (PEKK) as an ideal matrix. However, its inherently high melt viscosity and complex crystallization behavior usually result in inadequate fiber wetting, elevated porosity, and weak interfacial adhesion, severely limiting composite strength. This paper presents a method to dissolve and disperse PEKK in dichloroacetic acid (DCA) at room temperature and pressure, combined with a “gradient impregnation‐temperature‐controlled quenching porosity reduction and toughening” fabrication strategy, which produces CF/PEKK composites with low‐porosity, high‐strength. A multiscale finite element model is developed to simulate the mechanical response. DCA enables nanoscale dissolution and dispersion of PEKK, with 99.6% of the particles in the 10–50 nm size range. Gradient impregnation reduces the composite porosity (equivalent radius> 9 um) to 0.84%. At 40 wt% resin, quenched CF/PEKK achieves optimal performance with 960 MPa tensile strength; at 50 wt%, it improves 20% and 25% over powder and film layup methods, respectively. SEM reveals that quenching induces a fracture mode dominated by fiber pull‐out combined with ductile resin tearing. The finite element simulations deviate from the experimental values by 20.4%. This work establishes a novel fabrication approach for high‐strength, low‐porosity CF/PEKK composites with tunable crystallinity.