Strengthening, toughening, and self‐healing for carbon fiber/epoxy composites based on PPESK electrospun coaxial nanofibers

A carbon fiber/epoxy composite modified by electrospun coaxial dicyclopentadiene/poly(phthalazinone ether sulfone ketone) (DCPD/PPESK) nanofibers was successfully fabricated, and the addition of DCPD/PPESK fibrous membranes made the composite have remarkable self‐healing ability, and meanwhile effectively improve its mechanical properties. Results of polarization microscope observation and thermogravimetric analysis confirmed liquid DCPD as the healing agent was encapsulated into the PPESK coaxial nanofiber. Three‐point bending test was utilized to evaluate the mechanical properties and self‐healing effect of the composite. Experimental results indicated that the embedded nanofibers significantly improved the toughness of the composite, and maintained good mechanical properties even at low resin content. Most importantly, the flexural strength of the composite recovered to close to 90% observed 2 h after the bending failure.