Researchers at Technische Universität Wien (TU-Wien) in Vienna, Austria, have developed a “special formula” that allows epoxy-based composites to cure underwater. The research group, headed up by Professor Robert Liska, has developed additives that are added to ordinary epoxy resin in order to adjust its properties and enable targeted curing at the touch of a button.

As TU-Wien explains, the resin material begins in a in liquid or paste form. Then, when any part of it is irradiated with the appropriate light, the entire resin begins to solidify and takes on a dark color. The special epoxy resin formula that makes this possible has been patented by the university.

“We are developing special compounds in which light triggers a chemical reaction,” says Liska. “This can be a bright flash of visible light, but we also have compounds which only react to UV light.” At the point where the light strikes the resin, a reaction is started that releases heat. This heat spreads and initiates a chemical cascade elsewhere until all the resin has been cured. “The key advantage of this method is that it isn’t necessary to illuminate the entire resin as with other light-curing materials. It’s sufficient to irradiate any part of the resin with light. The rest then cures even if it’s situated deep in a dark crack that you want to fill.”

The researchers have even successfully carried out the process underwater. This means that the new epoxy resin can be used for jobs that, up until now, had been very difficult to carry out, such as filling underwater cracks in bridge pillars or dams, or repairing pipes during ongoing operation.

Furthermore, the special formula can be applied in combination with carbon fibers and carbon fiber mats. Many possibilities arise for applications in aerospace engineering, wind turbines, shipbuilding or automotive industry.

Researchers are now looking for further users from industry to explore the potential of this special resin. Besides the application of glass- and carbon fiber-reinforced composites in aerospace, shipbuilding and automotive manufacturing, the restoration of buildings is a particularly interesting area. For example, you could fill cracks in buildings that are built in water with viscous resin and then cure them with a flash of light. The maintenance of pipelines is another job that is often difficult to carry out – the use of the new resin could also be suitable here. “There are many possibilities and we are hoping for some interesting new ideas,” says Liska.