High crack self-healing efficiency and enhanced free-edge delamination resistance of carbon fibrous composites with hierarchical interleaves

Abstract

Carbon nanotube (CNT), poly(ethylene-co-methacrylic acid) (EMAA) and epoxy (EP) are used to prepare a hierarchical interleaf, consisting of [CNT/EP/EMAA]s sandwich structure with periodic EP column arrays, which can act as crack self-healing interface within carbon fiber reinforced plastic (CFRP) by in-situ electrical-heating the CNTs. Results show that the introduced [CNT/EP/EMAA]s interleaf has little effect on the free-edge delamination initiation stress (<±3.2%) and the in-plane strength (<±1.2%) of the baseline CFRP. But, the interleaved CFRP shows high self-healing efficiencies of 99.1–111.3% to the delamination initiation stress and 97.9–99.4% to the elastic modulus, respectively, from two delamination initiation-healing circles activated by electrical-heating the embedded CNTs, as well as with a maintenance of 92.6–99.7% to the tensile ultimate strength. This study reveals that the [CNT/EP/EMAA]s interleaf and the electrical-heating activated self-healing method are promising to effectively restore the initial damage of CFRP without decreasing the in-plane strength, unlike the traditional pure EMAA interleaf.