Weathering of a polyester-urethane clearcoat:lateral inhomogeneities

This paper is devoted to the surface analysis of a polyester-urethane coating during weathering under different conditions using artificial weathering machines. By means of atomic force microscopy (AFM), the evolution of the surface topology of the coatings is studied. Degradation is shown to be a laterally inhomogeneous process. The presence of water facilitates material removal and leads to an increase in the surface roughness and consequently a gloss loss. In addition, by comparing degradation under aerobic and anaerobic conditions, it is shown that oxidation reactions are the main cause of lateral inhomogeneous degradation of coatings.