High‐performance self‐healing epoxy by microencapsulated epoxy‐amine chemistry II: Performance of the system

Abstract The self‐healing epoxy based on microencapsulated epoxy‐amine chemistry is a system with great potential for practical applications. Herein, microcapsules respectively containing epoxy and polyetheramine were fabricated using a microencapsulation technique via integrating electrospraying and interfacial polymerization (ES‐IP) and self‐healing epoxy based on the dual microcapsules were systematically investigated regarding the microcapsule dispersion, healing performance, failure mode, and mechanical properties. Microcapsules with different sizes were conveniently prepared by adjusting the injection rate. The microcapsules, regardless of the size, can be well dispersed in the epoxy matrix. The effects of the microcapsule size and concentration on the healing performance were studied. While full healing can be obtained for microcapsule >100 μm, high healing efficiency of about 90% and 70% can be achieved for microcapsules in 50 ~ 100 μm and ~ 50 μm, respectively. The healing performance decreases with the decreased microcapsule concentration. However, healing efficiency >70% can still be obtained when 5.0 wt% microcapsule of 50 ~ 100 μm were adopted. Mixed failure modes including adhesive failure, cohesive failure, and matrix failure, were observed, due to the good performance of the selected healant system. While the incorporated microcapsules, especially the small ones, evidently toughens the matrix, they deteriorate the tensile properties of the formulated self‐healing material.