Material BehaviourSelection of healing agents for a vascular self-healing application

To increase the durability and reliability of thermosets, self-healing via a vascular network, is developed. A judicious choice of healing agents proves to be necessary to achieve the best recovery of properties. Four low viscosity two-component epoxy-amine healing systems were compared, to check which glass transition temperature range would be best to recover mechanical properties (Tg ranging from −8 to 68 °C). Interdiffusion experiments show that all systems react sufficiently slowly at room temperature to allow interdiffusion of epoxy and amine over more than 1 mm before the diffusion is stopped by vitrification. Swelling tests revealed that most of the selected healing agents diffuse into the surrounding matrix and swell it. This might be beneficial for crack closure and improved adhesion between healing system and matrix. Flexural tests demonstrated that, the higher the glass transition temperature of the fully cured healing system, the higher the healing capability.