Mechanical behavior and self-healing effect of composite plate with pure polyamine and epoxy microcapsules subjected to impact fracture

Self-healing composites are widely used in the interest of their autonomous repairing capability, which is of great importance in composite components and structures. This study applied pure polyamine microcapsules through the microfluidic emulsion technique and epoxy microcapsules through the in-situ polymerization method to fabricate the dual microcapsules system to achieve excellent healing performance at room temperature. Three different crack patterns were generated through an in-house low-velocity impact setup. Results indicate that the self-healing composite plate behaves with a relatively stable healing efficiency. In contrast, the infiltrated neat resin plate and composite plate without self-healing microcapsules show dramatic reductions in the elastic modulus and energy absorption with different crack patterns. A quantitative relationship between the normalized modulus and the crack length is established for all self-healing composite plates, infiltrated net resin plates, and infiltrated composite plates. Moreover, many factors influence the healing efficiency of the composite plate, such as the crack pattern and length, the size of the microcapsule, the healing condition, etc., which provides references for the optimization of self-healing composites. Composite plates with smaller microcapsules have higher healing efficiency (81.7 %). The excessive polyamine microcapsule benefits the fabricated composite's mechanical properties. Meanwhile, repeated healing is achieved as the composite with the developed dual microcapsules system shows a 44.8 % healing efficiency after a second impact.