Healing efficiency and mechanical properties of repeatable self-healing carbon fiber reinforced polymer composites

Repeatable self-healing composites have attracted attention for their ability to extend the service life and reduce overall life cycle costs in long-term applications. In this study, repeatable self-healing carbon fiber reinforced polymer composites (RSH-CFRPs) were produced by dispersing microcapsules containing hardener and hollow glass fibers containing two types of microcapsules and self-healing resin (HGFs-Ms) into the matrix. The repeated self-healing efficiency and mechanical properties were studied using tensile, three-point flexure, short-beam shear, and double-cantilever beam tests. The results showed that both the first and second self-healing efficiencies in mode I interlaminar fracture toughness of the RSH-CFRPs exceeded 75%. Moreover, the incorporation of HGFs-Ms and microcapsules containing hardener enhanced the interlaminar fracture toughness and interlaminar shear strength by 28.36% and 26.19%, respectively. However, the RSH-CFRPs exhibited lower tensile and flexural properties compared to laminates without HGFs-Ms and microcapsules. Furthermore, the failure mechanisms of the RSH-CFRPs were extensively analyzed through macroscopic and microscopic observations of the fracture surfaces. The outcomes of this study offer valuable insights for the design and optimization of RSH-CFRPs.