Self-healing of fatigue damage in cross-ply glass/epoxy laminates

Abstract Self-healing of fatigue damage is reported in laminated composites fabricated from unidirectional glass/epoxy prepreg with embedded microcapsules. Microcapsules (ca. 2.5 μm) containing a mixture of ethyl phenylacetate (EPA) solvent and diglycidyl ether of bisphenol A (DGEBA) epoxy are seamlessly incorporated into cross-ply [ ( 0 / 90 3 ) 4 / 0 ] T laminated composites. Specimens subjected to tension-tension fatigue testing followed by a 24 h rest period at ambient conditions recover 52% of the initial Young's modulus as a result of self-healing. Fluorescent labeling of microcapsules and matrix resin combined with confocal fluorescent imaging reveals that the healing agents wick into transverse fatigue cracks, ultimately rebonding the crack faces after self-healing. Furthermore, self-healing composite laminates exhibit a higher resistance to crack growth as a result of the presence of the embedded microcapsules. The fatigue behavior of laminated self-healing composites demonstrates the potential for extended fatigue life of fiber-reinforced polymer composites for structural applications.