Coupling mechanism and process optimization of pore-mechanical properties in hot-press forming of CCF/PEKK laminates

In view of the high strength and high reliability requirements of composite pallet covers for load-bearing drones, this study focuses on the quantitative coupling relationship between process parameters–porosity–mechanical properties in CCF/PEKK hot-pressing forming. The Box–Behnken response surface method was used to establish the regression model of forming temperature, pressure and holding time on flexural strength, interlaminar shear strength (ILSS), and porosity ( R ² > 0.98). Results show that: for every 1% increase in porosity, the flexural strength decreases by about 83 MPa, and the ILSS decreases by about 3.4 MPa; the flexural strength and ILSS have a strong positive correlation ( r = 0.967), indicating that both are strongly correlated with porosity; the flexural strength exhibits a stronger correlation with porosity compared with ILSS, as bending stress tends to concentrate around pores while shear stress can be redistributed. The temperature × pressure interaction shows significant synergy on pore control ( p = 0.0008). SEM confirmed that low-porosity samples showed matrix ductile fracture characteristics, while high-porosity samples showed interface debonding. Optimal process via multi-objective optimization: 370.14°C, 8.12 MPa, 21.97 min, with verification error < 5%. This suggests a quantitative “process–pore–performance” relationship, providing a useful reference and preliminary process window.