Synergistic Enhancement of Interlaminar Fracture Toughness in CFRP Using Polyethersulfone/Carbon Nanotubes/Nano‐Alumina Electrospun Hybrid Interleaves

To enhance the interlaminar fracture toughness of carbon fiber‐reinforced polymer (CFRP) composites, electrospinning was employed to fabricate PES/CNTs/nano‐Al 2 O 3 composite fiber interleaves, which were introduced as interlaminar toughening layers in CFRP laminates. By varying the mass ratio of CNTs to nano‐Al 2 O 3 and the total nanofiller content (0.3–1.0 wt%), the effects of different hybrid configurations on Mode I and Mode II interlaminar fracture behavior were systematically investigated. The morphology of the hybrid structures and the fracture surface microstructure were characterized using scanning electron microscopy (SEM). Interlaminar fracture toughness was evaluated through double cantilever beam (DCB) and end‐notched flexure (ENF) tests. For Mode I fracture, when the CNTs/nano‐Al 2 O 3 mass ratio was 3:2 and the nanofiller content was 0.5 wt%, G IC‐c and G IC‐p increased by 131.72% and 83.90%, respectively. For Mode II fracture, a CNTs/nano‐Al 2 O 3 mass ratio of 2:3 combined with a nanofiller content of 0.7 wt% resulted in a 219.50% increase in G IIC . The results indicate that the nanofillers and PES fibers form a synergistic toughening architecture within the interlaminar region, providing experimental evidence and theoretical support for developing multiscale synergistic toughening systems and optimizing the interlaminar structure design of CFRP composites.