Micromechanical behavior of self-healing epoxy and hardener-loaded microcapsules by nanoindentation

Nanoindentation is a widely used method for measuring the micromechanical properties of thin films and micro scale materials. Self-healing polymeric materials have the built-in capability to substantially recover their load transferring ability after damage. One of the main self-healing strategies incorporates microencapsulated healing agents within a polymer matrix to produce a polymer composite capable of self-healing. In this study, microcapsules containing, respectively, epoxy (resin) and mercaptan (hardener) were investigated with poly (melamine-formaldehyde) (PMF) as the shell material. The micromechanical behavior of microcapsules was tested using nanoindentation. The results show that the PMF shell material behaves as a viscoelastic plastic material. The modulus and hardness of the microcapsules were determined quantitatively. The size and loaded-component of microcapsules (i.e., hardener or resin) have a significant effect on the micromechanical properties of the microcapsules.

► Micromechanical properties of microcapsules.
► The size effect.
► The loaded-component effect.