Self-repairing materials

This release is available in Spanish.

Will the day come when cracks in buildings close up without external help and before they get to the stage where they cause damage to the component? This might appear utopia, but it already occurs in nature. When a person suffers a minor wound, the human body reacts to close the opening, sending the blood platelets needed to the affected area – and with no need in many cases for any external coagulant substance to be employed.

This reaction of nature to damage suffered was the starting point for the development of self-repairing polymer materials with the capacity of recovering a good part of the properties lost and with no or with minimal external help. In the case of ceramics or metallic materials, progress is much slower, being limited to initial steps.

There are currently two notable self-repairing technologies in polymer materials: adhesives and thermal encapsulation.

As the name suggests, the first of these involves a series of "stores" of adhesive found distributed in the most homogenous manner possible throughout the material, so that when the crack reaches one of these nodes the adhesive is secreted, together with a catalyst, and the crack is closed and the material polymerised.

There are two variants within this line of technology, depending on whether adhesive-containing microcapsules or tubes filled with adhesive are employed.

INASMET-Tecnalia has worked on this line in a project undertaken for the AIRBUS, having managed to produce a series of microcapsules and distribute them in a polymeric resin. This was a fundamental step to finding out the difficulties that might arise in the encapsulation process.