Study of the mechanism of degradation of pyrene-based pressure sensitive paints

Even though pyrene-based pressure sensitive paints have some special advantages like high quantum efficiency, good pressure sensitivity and low temperature sensitivity, these paints exhibit steady degradation of the fluorescent intensity after each wind tunnel test. It has been reported that pyrene-based paints degrade because pyrene has a tendency to evaporate. It is necessary to understand the mechanism of degradation of pyrene-based paints in order to find a solution to this problem. Thermal aging tests and UV exposure tests of the paint specimens are carried out to study the effect of experimental parameters like temperature, pressure and UV exposure on the paint stability. This study has shown that the paint degradation in wind tunnel is mainly due to diffusion and evaporation of pyrene. The effect of pyrene concentration in the paint and the thickness of the active layer on the paint stability were also studied.