SUMMARY
Self-healing is the capacity of a material to repair itself after being damaged and to recover its physical and mechanical properties without human intervention. Two types of self-healing materials currently exist, namely materials whose repair is either extrinsically or intrinsically induced. The addition of this property makes it possible to avoid the replacement of damaged parts, to reduce the production of waste by increasing the material lifespan and to avoid the reproduction of certain impacting stages of the product’s life cycle.
CONCEPT
Intrinsic self-healing investigated within STELLAR project is based on reversible chemical bonds that can regenerate after being broken by external damage or on dynamical interactions like hydrogen or ionic bonding. Self-healing moieties can be incorporated into a polymer matrix before polymerisation to enable further recombination of the polymer chains. Depending on the chemical nature of those moieties, self-healing can be induced by various stimuli like heat, humidity, UV-light, etc. or without any stimulus.
Achieving self-healing behaviour in polymer materials does not only rely on the introduction of self-healing moieties since those reactive groups have to be able to meet after being separated from each other in order to recombine. Polymer’s flexibility, enabling its chains to be mobile and to diffuse within the crack, is by consequence a critical property of self-healing polymers. Flexibility in originally hard and rigid materials can be enhanced by the incorporation of long and soft segments within the matrix
TECHNICAL ADVANTAGES
Self-healing makes possible to drastically increase the lifespan of materials by lowering the impacts of damages occurring during their operation. In contrast to external self-healing, intrinsic self-healing hypothetically enables a material to be repaired an infinite amount of time.
INPUT IN STELLAR
By crashing at high speed onto leading edges of aircraft parts, insects can induce microfractures to the coating layers, lowering their lifetime and protective efficiency. Incorporation of self-healing property into polyurethane anticorrosion coating for STELLAR project will enable to repair those microfractures and lower the impact of those disturbances, increasing the lifespan and protectiveness of the coating.