Micromechanical properties and morphologies of self-healing epoxy nanocomposites with microencapsulated healing agent

• Micromechanical properties of composites were studied before and after healing.
• Nanoindentation test is used on the composites at three different normal loads.
• The surface topographies of the indented regions were monitored via AFM.
• Healing efficiency was evaluated using AFM after nanoscratch test on the composites.
• Microstructures of virgin and healed self-healing composites were determined via SEM.

The effects of microcapsules and carbon nanotubes (CNTs) on the micromechanical properties (elastic modulus, hardness and plasticity index) of self-healing epoxy polymers were investigated via nanoindentation. A standard Berkovich indenter was used to make indentations under three different normal loads. The surface topographies of the indented regions were monitored via AFM to compare the plasticity of the samples. A nanoscratch test was performed on the self-healing composites, and the healing efficiency was evaluated using AFM. The addition of microcapsules reduced the elastic modulus and hardness of the pure polymer matrix; however, the addition of CNTs significantly improved these mechanical properties. We also used nanoindentation tests in the scratched region to study the mechanical properties of the self-healing composite after healing. Furthermore, the microstructures of both the virgin and healed self-healing composites were determined via SEM. This analysis showed that the microcapsules ruptured during scratch propagation and the healing agent release into the cracks.