Electrospinning core-shell nanofibers for interfacial toughening and self-healing of carbon-fiber/epoxy composites

This article reports a novel hybrid multiscale carbon-fiber/epoxy composite reinforced with self-healing core-shell nanofibers at interfaces. The ultrathin self-healing fibers were fabricated by means of coelectrospinning, in which liquid dicyclopentadiene (DCPD) as the healing agent was enwrapped into polyacrylonitrile (PAN) to form core-shell DCPD/PAN nanofibers. These core-shell nanofibers were incorporated at interfaces of neighboring carbon-fiber fabrics prior to resin infusion and formed into ultrathin self-healing interlayers after resin infusion and curing. The core-shell DCPD/PAN fibers are expected to function to self-repair the interfacial damages in composite laminates, e.g., delamination. Wet layup, followed by vacuum-assisted resin transfer molding (VARTM) technique, was used to process the proof-of-concept hybrid multiscale self-healing composite. Three-point bending test was utilized to evaluate the self-healing effect of the core-shell nanofibers on the flexural stiffness of the composite laminate after predamage failure. Experimental results indicate that the flexural stiffness of such novel self-healing composite after predamage failure can be completely recovered by the self-healing nanofiber interlayers. Scanning electron microscope (SEM) was utilized for fractographical analysis of the failed samples. SEM micrographs clearly evidenced the release of healing agent at laminate interfaces and the toughening and self-healing mechanisms of the core-shell nanofibers. This study expects a family of novel high-strength, lightweight structural polymer composites with self-healing function for potential use in aerospace and aeronautical structures, sports utilities, etc.