Bicomponent microcapsule-driven self-healing in glass fiber composites for thermal and low-velocity impact resilience

Self-healing composites are gaining attention for improving the durability of structural materials. This study examines the impact of embedding bicomponent epoxy resin and amine-based hardener microcapsules (5 wt%, 10 wt%, and 15 wt%) in Glass Fiber-Reinforced Polymer (GFRP) composites. The microcapsules, with a polymethyl methacrylate (PMMA) shell, were characterized using optical and Scanning Electron Microscopy (SEM), confirming average diameters of 36 µm (epoxy) and 20 µm (hardener). Low-velocity impact tests (4 m/s) and three-point flexural tests assessed residual strength. Fourier Transform Infrared (FTIR) spectroscopy validated the chemical composition, while Thermogravimetric Analysis (TGA) indicated improved thermal stability. Dynamic Mechanical Analysis (DMA) showed decreased storage modulus and glass transition temperature with higher microcapsule content. Impact testing revealed an optimal 10 wt% concentration, improving peak load by 1.79% and maximizing self-healing efficiency at 76.23%. However, at 15 wt%, structural degradation was observed due to microvoid formation. The 10 wt% formulation offers the best balance of impact resistance, mechanical integrity, and self-healing, making it highly suitable for aerospace and automotive applications where damage tolerance is crucial.