Core ( PCL )‐Shell ( PEBA ) Nanofiber Interleaves for Toughening and Staged Thermal Recovery of CFRP /Epoxy Laminates

Abstract

ABSTRACT This work developed thermally responsive carbon fiber/epoxy laminates based on PCL@PEBA core‐shell electrospun nanofiber interleaves to improve both interlaminar toughness and post‐damage performance recovery. The core‐shell nanofibers were prepared by coaxial electrospinning, where the low‐melting PCL core was designed to flow into damaged interlaminar regions during low‐temperature thermal treatment, while the PEBA shell helped maintain the fibrous interleaf structure during composite curing and provided an additional thermoplastic phase during higher‐temperature recovery. After being introduced into the interlaminar region of CFRP laminates, the nanofiber interleaf altered crack propagation during delamination and assisted crack filling after damage. The optimized NF‐6.24 laminate increased G IC,ini and G IC,prop by 63.59% and 86.57%, respectively, compared with the control laminate. Its initial ILSS also increased by 22.2%. After cyclic short‐beam shear damage, the NF‐6.24 laminate retained 91.8% and 70.9% of its initial ILSS after the first and second recovery treatments at 65°C, respectively. A subsequent treatment at 150°C increased the ILSS retention to 85.4%, indicating the staged thermal recovery behavior of the PCL@PEBA interleaf. These results suggest that core‐shell electrospun nanofiber interleaves can provide a practical route for combining interlaminar toughening with thermally assisted post‐damage recovery in CFRP/epoxy laminates.