Although rubbers are widely used in load-bearing engineering applications where lightweight and flexibility are essential, they are typically designed thicker than they need to be due to a poor prediction of their lifetime in use. Predicting the onset of fracture of rubbers is currently impossible because it starts with the random scission of chemical bonds without any detectable change in the readily measurable elasticity before catastrophic failure (no or little detectable plasticity precedes the nucleation and growth of a crack).
The method that we proposed in FLUODAMAGE is adapted to non-destructive testing of rubbers and is much more sensitive to small extents of damage. It is a direct imaging method where you see the damage and can quantify it by the intensity of the fluorescence. It can detect degradation at a much earlier stage than current methods and could potentially be used as a non-destructive tool (the same sample can be analyzed several times during its lifetime, enabling monitoring of the damage evolution). Within the timeframe of the project we demonstrated that our fluorescent molecule reporting molecular damage is stable over months up to 80°C and can be use to detect damage in mechanically fatigued samples.
A key result of the project was a viable chemical route to incorporate mechanophores as crosslinkers in conventionally vulcanized elastomers at room or low temperature. This success opens many possibilities since the mechanophore damage reporting molecule can be incorporated in the rubber material after its manufacturing and at low temperature avoiding the damaging high temperature processes needed to manufacture the material. Once incorporating the molecule the molecular damage can be followed over time with an optical set-up able to detect fluorescence.
