Surface structure build‐up and three‐dimensional topography of polyurethane powder coatings

Non‐ and polysilsesquioxane‐containing polyurethane‐based powder coating systems, crosslinked with allophanate bonds containing polyisocyanates were examined. The surface structure built‐up of the powder coatings were investigated at different temperatures with a polarized optical microscopy (POM) using reflected light. The three‐dimensional surface topography and the values of surface roughness were determined. The surface structure was correlated with the chemical structure of the coatings and macroscopic surface behavior: surface free energy and gloss. These experimental results lead to a better understanding of the development of surface topography and morphology and provide valuable information for the development of new polyurethane powder coating systems.