Unique light-activated resin hardens even when underwater
While we've certainly heard of epoxy resins that harden when exposed to light, usually all of the substance has to be exposed. A new additive causes resin to solidify when even only a bit of it gets lit up, however – plus it works underwater.
Developed at the Vienna University of Technology, the proprietary compound can be added to existing epoxy resins in either a liquid or paste form.
Initially, it's transparent. When any part of the resin is irradiated by a flash of light, though, a chemical reaction occurs that generates heat. That heat spreads throughout the resin, resulting in a cascade effect that causes all of the material to cure and harden within seconds – this even includes bits that may be hidden from the light, down inside cracks or whatnot.
The resin turns a darker color at this point, letting users know that the process is complete.
Currently, the additive is triggered by either ultraviolet or high-intensity visible light, depending on its formulation. Importantly, it still works when the resin is mixed with carbon fibers, meaning that it could be used in the production or repair of composite materials.
And yes, resin containing the additive can even be applied and then cured underwater. At first, the scientists assumed that the heat generated within the resin would dissipate out into the water, keeping the material from solidifying. It turned out, however, that the chemical reaction caused the water immediately surrounding the resin to boil, creating a protective layer of water vapor along the material's surface.
The university is now looking for industry partners that may be interested in commercializing the technology. It could ultimately find use in applications such as aerospace, shipbuilding, structure restoration, or pipeline repair.
A paper on the research, which is being led by Prof. Robert Liska, was recently published in the journal Composites Part A: Applied Science and Manufacturing.