Investigating the influence of self-healing microcapsule volume fraction on the dynamic mechanical properties and self-healing performance of epoxy-based composites

This study investigates the incorporation of urea-formaldehyde (UF) microcapsules containing dicyclopentadiene (DCPD) into an epoxy matrix augmented with Grubbs’ catalyst. Composite samples with varying microcapsule volume fractions (0%, 10%, and 20%) were extensively characterized to evaluate thermal transitions, viscoelastic properties, and self-healing efficiency using dynamic mechanical analysis (DMA). The microcapsules, analyzed via laser scanning microscopy, FTIR, DSC, and TGA, exhibited an average size of 108.6 ± 18.8 μm with a rough surface texture. FTIR confirmed high DCPD content within UF microcapsules, underscoring the need for further exploration of UF/DCPD interactions with Grubbs’ catalyst. Thermal analysis revealed a multi-step degradation process and a decomposition temperature suitable for moderate thermal environments. SEM and digital microscopy demonstrated uniform distribution and successful incorporation of microcapsules within the epoxy matrix. DMA, conducted cyclically, revealed significant improvements in self-healing efficiency with repeated testing, particularly in composites with 20 vol% microcapsules showing up to 43.5% healing efficiency. This enhancement suggests increased healing agent availability and mobility with higher microcapsule content, facilitating effective crack repair and modifying mechanical properties. The study contributes comprehensive insights into the viscoelastic behavior and self-healing efficacy of these composites under operational conditions, highlighting potential applications in durable materials requiring autonomous repair capabilities.