Abstract: An ultrathin core-shell nanofiber mats were prepared by encapsulating a mixture of the foaming agent diethyl azodicarboxylate (DEAD) and epoxy resin (EP) into polyacrylonitrile (PAN) nanofibers by coaxial electrostatic spinning technique and laying them on the interface of carbon fiber fabric, and forming CFRP with ultrathin self-healing smart sandwich after resin injection and curing. The self-healing effect of the ultrathin self-healing smart sandwich on the bending strength of CFRP laminates with damage failure was evaluated using a three-point bending test. The results showed that the thermal properties of PAN core-shell nanofibers and its encapsulated self-healing agent matched with the CFRP preparation and molding process. When the DEAD content was 5wt% and the healing temperature/healing time (T/t) was 150 ℃/30 min, the self-healing efficiency of CFRP reached 93.5% at 100%L primary bending damage, which was improved by 12.0% compared with that without DEAD in the self-healing agent. Under the bending load with loading displacement of 100%L, 90%L and 80%L, respectively, the self-healing efficiency still reached 71.2%, 70.2% and 84.0% after three damage repairs, indicating that the composite still has self-healing ability after multiple damages.

Key words: composite materials, core-shell nanofibers, self-pressurization, self-healing, multiple healing