ETH Zurich researchers working in collaboration with researchers from the University of Fribourg have developed a new type of laminate that changes color as soon as the material is deformed.
Translucent laminate is composed of alternating layers of a plastic polymer and artificial nacre. The latter is modeled on the biological example of the mussel shell. It consists of countless glass platelets arranged in parallel, which are compacted, sintered and solidified using an polymeric resin. The second layer consists of a polymer to which the researchers added an indicator molecule synthesized specifically for this application. The molecule is activated as soon as the polymer experiences stretching forces, and this changes its fluorescence. The more the material stretches and the more of these molecules are activated, the more intense the fluorescence becomes.
With the help of fluorescence, the researchers can now identify overstressed areas within the composite material even before fractures form. This allows early detection of vulnerable areas in a structure before catastrophic failure occurs. One possible application of the novel laminate is in components in the load-bearing structures found in buildings, aircraft or vehicles, where it is essential to detect their failure at an early stage.
However, it remains to be seen whether and how the material can be produced on an industrial scale. So far, it exists only at laboratory scale as a proof of concept.