Experimental investigation of flexural properties of glass fiber–epoxy self-healable composite structures containing capsulated epoxy healing agent and NiCl ₂ (imidazole) ₄ catalyst

In this work, the glass fiber–epoxy self-healable composites containing the capsulated healing agent as smart composite structures were fabricated. Then, the effects of various percentage of capsulated epoxy (7, 14, and 21 wt.%) and different damage forces (400, 500, and 600 N) on the healing ability of composites under the flexural loading were investigated. The obtained results showed that by increasing the percentage of microcapsules, the flexural strength of composites was slightly reduced, whereas the healing ability of those was improved. The full recovery of initial flexural strength was obtained in the composite containing 21 wt.% microcapsules under the damage force of 400 N. By increasing the damage force, the healing ability of composites was reduced, because the damage mechanisms were changed from matrix cracking to fiber breakage. The microscopical investigations on the microcapsules/micro-cracks behaviors illustrated the deflecting, debonding, crushing, and buckling phenomena under the flexural loading. Considering with the healing efficiency and initial flexural strength, the self-healable composite containing 14 wt.% microcapsules and 2 wt.% NiCl ₂ (imidazole) ₄ catalyst had the optimum results.