Studies on the thermal ageing of organic coatings

The ageing of organic protective coatings depends on environmental impacts and is associated with a variety of ichemical and physical processes. The results of former thermal ageing studies indicate that evaporation and polymer degradation are the decisive processes for changes in coating properties. For the verification of these assumptions the impact of - the thermal exposure temperature T_L and - the length of the exposure time t_L on properties of clear lacquer coatings was determined by further studies. The gradation of T_L was aimed at creating conditions where on the one hand only evaporation processes occur, while on the other hand evaporation and polymer degradation reactions occur in parallel. The objective was to find the time t_L and the temperature T_L at which degradation starts to prevail.