Self-repairing materials

Apr 17, 2008

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.

The second method, developed by Bristol University, is a project for the ESA, is very similar. The difference lies in the use of tubes rather than microcapsules filled with adhesive.

The thermal method uses a different repair methodology. The material, developed by the University of Sheffield, is a polymeric matrix compound, reinforced with carbon fibres. The polymer matriz, in turn, is made of a solid solution of a thermoplastic polymer and another thermostable polymer.

The only restriction of the thermostable material is that it has to be suitable for incorporating these reinforcment fibres into it. The thermoplastic material has greater limitations, limiting it chances of being chosen for use, being highly dependant on the thermostable material used. In this case, when damage is detected, repair is carried out by heating the material with some device incorporated into it.

This heating is capable of raising the temperature above that of the fusion of the thermoplastic material which, as a result, melts and flows into the damaged areas so that the cracks are sealed and the component restored to its former condition. INASMET-Tecnalia has also worked in this field within the framework of the aforementioned project.

It should be underlined that the development of self-repairing materials is still at initial stages and there is a long way to go yet before reaching the desired goal. Nevertheless, the results obtained are encouraging.

Apart from participation in this project, INASMET-Tecnalia is working on a number of research lines related to the growing demand that is anticipated for self-repairing materials.

Source: Elhuyar Fundazioa

Explore further: Researchers develop method of fabricating perovskite solar cells that is more efficient, costs less

Related Stories

Finger gestures will tell your smartwatch what to do

25 minutes ago

Gesture control for smartwatches is the key mission for a startup called Deus Ex Technology. They have devised a module which can fit into a smartwatch band and behave as a gesture controller for your timepiece. ...

NSA winds down once-secret phone-records collection program

22 hours ago

The National Security Agency has begun winding down its collection and storage of American phone records after the Senate failed to agree on a path forward to change or extend the once-secret program ahead of its expiration ...

Recommended for you

Defining a national standard for dynamic pressure waves

5 hours ago

In recent years, the physical damage done by pressure waves – such as traumatic brain injuries from explosives sustained by military personnel in the Middle East – has become an increasingly urgent public ...

Shedding light on untapped information in photons

6 hours ago

Conventional optical imaging systems today largely limit themselves to the measurement of light intensity, providing two-dimensional renderings of three-dimensional scenes and ignoring significant amounts ...

The art of hand-polishing precision optics

8 hours ago

Growing up in a household of artists and engineers, Peter Thelin was destined for a career in which artistry mattered. Only for him, art has come in the form of manipulating the shapes, sizes and qualities of optics. And ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.