Experimental and numerical research on healing performance of reinforced microcapsule-based self-healing polymers using nanoparticles

The effect of enhancing multicore microcapsules with various nanoparticles on the healing efficiency of microcapsule-based self-healing polymers was investigated in this study. The incorporated polymers with enhanced microcapsules by MWCNT, nanoclay, and nanosilica were fabricated. Three volume fractions (VFs) of microcapsules, including 5, 7.5, and 10% were added to the epoxy matrix. The maximum tensile stresses of the virgin, damaged by controlled low velocity impact test, and healed specimens were obtained to calculate the healing efficiencies of fabricated self-healing polymers. Also, a multi-scale FE modeling was promoted using RVEs generation and ABAQUS-Explicit solver attached with VUSDFLD subroutines to predict the healing efficiencies. The results indicated that by increasing the VF of microcapsules, the healing efficiencies of specimens were increased. Increasing the VF of the microcapsules could increase the probability of hitting induced cracks due to the LVI test with microcapsules. Thus, further spreading of healing agents into the propagated cracks would increase the healing efficiency of specimens containing higher VF of microcapsules. Also, increasing the strength of microcapsules reduced the healing efficiency of specimens. For instance, in the specimens containing 10% VF of enhanced microcapsules with MWCNT, the healing efficiency was 45.90%, while it was 50.41% for enhanced microcapsules with nanosilica. Increasing the mechanical properties of microcapsules could decrease the probability of rupturing damaged microcapsules, which reduced the healing efficiency of these specimens. Finally, the predicted healing efficiency of simulated RVEs had good accuracy, indicating the reliability of introduced multi-scale FEM.