Assessing the self-healable features in GFRP composites containing capsulated healing agent and MWCNT nanoparticles under tensile and shear conditions

This study investigated the mechanical self-healing behavior of GFRP composites. Self-healing microcapsules were synthesized via in situ polymerization, and an imidazole-based catalyst was prepared to facilitate the reaction of the healing agent encapsulated within the microcapsules. Composite samples containing 0.15 wt%, 0.3 wt%, and 0.45 wt% MWCNTs were fabricated using the hand lay-up method. To evaluate the healing behavior, the samples were first subjected to controlled damage using a quasi-static penetration test, applying a force of 1800 N for tensile specimens and 4300 N for ILSS specimens. Post-healing, the specimens underwent tensile and ILSS testing to assess the recovery of mechanical properties. Furthermore, Weibull analysis was employed in this study to statistically evaluate the variability and reliability of the mechanical performance of healed specimens. The results indicated that the healing agent effectively filled and healed microcracks and damaged areas, significantly restoring the composite's mechanical properties. Furthermore, increasing the MWCNT weight percentage up to 0.3 wt% enhanced the mechanical properties. However, at 0.45 wt% MWCNT, a decline in mechanical performance was observed, attributed to excessive nanoparticle dispersion causing stress concentrations. Additionally, the healing efficiency decreased with increasing MWCNT content, suggesting that higher nanoparticle concentrations interfered with the self-healing process.