Synergistic enhancement of strength and toughness of fiber-reinforced composites by constructing biomimetic intermittent porous structure

Achieving a balance between strength and toughness is a vital requirement for the development of high-performance fiber-reinforced composites. Inspired by nature, this study integrates biomimetic intermittent porous carbon nanotubes (PCNT) structure into the composite for synergistically enhancing its strength and toughness. It was found that the interfacial shear strength, interfacial fracture toughness, 45FBT tensile strength, and interlaminar fracture toughness of the intermittent porous structure-coated fiber/resin composites obtained significant increases of 63.4%, 107.7%, 31.2%, and 64.3% than the baseline composites, respectively. The strengthening effect was contributed by the synergistic enhancement of the interfacial bonding areas and mechanical interlocking morphologies, as well as the significant frictional stresses induced by the morphological mismatches between adjacent gaps. The toughening mechanism was associated with the micro-crack formation, the PCNT structure rupture, and the crack deflection during the crack propagation. This work provides a promising pathway to overcome the trade-off between strength and toughness.