Effect of nano-ZnO addition on the silicone-modified alkyd-based waterborne coatings on its mechanical and heat-resistance properties

A silicone-modified alkyd-based waterborne coating was developed using hexamethylmethoxymelamine (HMMM) as crosslinking agent and para-toluene sulphonic acid (p-TSA) as catalyst. The crosslinking ratio for resin and HMMM was fixed to 70:30, based on FTIR and DSC studies. Nano-ZnO particles were added to this system in different concentrations. The coatings with nano-ZnO particles were characterized using FTIR and DSC. The nano-composite coatings were applied on mild steel panels and were cured at 130 °C for 30 min. The coatings were evaluated for their mechanical and heat-resistance properties. They were exposed to 350 °C for 10 min followed by water quenching. The process was repeated for 10 cycles. Heat-resistance property of the coatings was examined by TGA. Also, surface morphological changes were assessed using SEM and optical microscopy. It was found that the heat-resistance and mechanical properties of the coatings improved significantly as a function of nano-ZnO addition.