An interfacial regulation strategy for superior interlaminar toughness: Harnessing resin diffusion and CNT interlocking in core-shell fibers of CF/PPESK composites

Carbon fiber-reinforced high-performance thermoplastic polymer composites (CFRHPTPC) generally suffer from insufficient interlaminar toughness and susceptibility to delamination failure. This study employed coaxial electrospinning combined with an etching process to fabricate an electrospun fiber veil featuring exposed CNT structures on its surface. The electrospun fiber veils enhance the interfacial bonding strength between the electrospun fibers and the resin matrix through the synergistic effect of shell resin diffusion and mechanical interlocking of CNT. This approach effectively overcomes the low interfacial bonding strength caused by the surface inertness of high-temperature-resistant electrospun fiber, significantly enhancing the interlaminar toughness and in-plane mechanical properties of CF/PPESK composites. This study further elucidated the diffusion and bonding strength of the resins at the molecular level through molecular dynamics simulations, and quantitatively characterized the diffusion thickness via AFM-Nano IR. The results indicate that the G IC,ini and G IC,prop of the modified composite increased to 1195 J/m 2 and 1300 J/m 2 (48% and 43% increases, respectively), while the maximum G IIC reached 2265 J/m 2 (131% increase). Additionally, the flexural strength, flexural modulus, and ILSS of CF/PPESK composites reached up to 1505 MPa, 114 GPa, and 70 MPa, respectively (increases of 25%, 21%, and 13%). These performance enhancements were attributed to the multiscale synergistic reinforcement mechanism at the electrospun fiber-resin interface, achieving simultaneous optimization of toughness and strength in the composite. This study provides novel insights and methodologies for synergistic reinforcement and toughening of CFRHPTPC through interlayer design of high-performance composites.