In situ investigation of the healing process in dual-microcapsule self-healing materials by the synchrotron radiation computed tomography

Microcapsule-based self-healing materials have attracted overwhelming attention for their smart damage recovery capability with great potential applications in aerospace, electronic devices, etc. Numerous experimental and numerical methods have been developed to analyze the healing performance. However, there is a lack of understanding of the in-situ damaging and healing process under external loading. Here, an in-situ investigation on the internal three-dimensional microstructure evolution and damaging-healing process of a dual-microcapsule-based self-healing material with fast healing chemistry was performed by SR-CT technology. Some important but previously undiscovered phenomena such as microcapsules rupture, crack propagation, healing liquids flowing and mixing were clearly observed. Further study combined with 3-Dimensional stress field analysis indicates that the healing behaviors have significant regional characteristics, and were affected by multiple factors including the geometric, internal defects and especially the gradient distribution of stress field. These results may provide useful guidance for the design and performance optimization of self-healing materials.