Interlamellar Toughening and Dual‐Temperature‐Triggered Repeated Self‐Healing in <scp>CFRP</scp> Based on Core‐Shell Nanofibers

ABSTRACT Carbon fiber reinforced polymer (CFRP) composites incorporating interlaminar thermoplastic core‐shell nanofibers exhibit promising repeatable self‐healing capabilities. However, the low loading efficiency of healing agents (core) leads to attenuation of self‐healing performance, limiting sustained material engineering applications. This study fabricated nanofiber membranes via coaxial electrospinning, employing high‐melting‐point polyether block amide (PEBA) as the shell and low‐melting‐point copolyamide (PA) as the core. The influence of veil thickness on mechanical properties and self‐healing behavior was systematically investigated. The high crystallinity of the PEBA shell confers exceptional morphological stability, preserving the chemical activity of the PA core during CFRP fabrication and service while suppressing interlaminar crack initiation through nanofiber entanglement. This resulted in a 19.17% increase in flexural strength and a 22.02% enhancement in interlaminar shear strength (ILSS). Furthermore, the structure enables a graded temperature‐responsive mechanism for dual‐stage healing: Microcracks induced by external forces puncture the PEBA, triggering PA melting at 135°C to fill primary cracks. Upon depletion of the core, residual damage zones are repaired by PEBA shell melting at 150°C. This achieves peak recovery rates of 88.92% in flexural strength and 97.57% in ILSS, realizing a “core‐dominated/shell‐supplemented” dual‐stage healing mechanism. This strategy significantly enhances multiple self‐healing efficiency under finite healing agent reserves.