Kinetics of degradation-induced polymer luminescence: Polyamide under dry heat exposure

The complex spectral and temporal changes of degradation-induced polymer photoluminescence of glass fiber reinforced polyamide under thermal degradation are evaluated with the aim to obtain apparent activation energies that could be used for polymer lifetime prediction. Two luminescence bands with different spectral and temporal behavior are identified. The kinetics are analyzed by the model-free approach of time-temperature superposition and by linearization based on non-linear variable transformations to gain information on their physico-chemical properties. In combination with the density of states model of degradation-induced polymer luminescence, for the first time, an empirical model function is developed that takes physically meaningful parameters to describe the luminescence kinetics and provides quantitative information on kinetic parameters. This empirical model function could then be used to create a linearized, temperature-independent master plot of degradation-induced polymer photoluminescence. The model-free approach of time-temperature superposition and the empirical model function both result in identical apparent activation energies that are also consistent with values reported in the literature.