Optimization of wear resistance of PU/TiO₂ coatings on aluminum surfaces

In this paper the effects of structural and process variables on wear resistance of polyurethane/titanium dioxide coatings on aluminium surface is studied. The parameters were polyol molecular weight, diisocyanate type, surface pretreatment method, NCO/OH ratio and pigment volume concentration. The experiments were carried out based on the design of experiments using Taguchi method. The analysis of variance showed that among the parameters studied, polyol molecular weight and pigment volume concentration have the most significant effects on wear resistance. Coatings with higher molecular weight polyol represent more resistance due to higher elongation at break of polymer which consequently increase the wear resistance of coating. The pigment particles provide equivalent physical crosslinks, so it increases the wear resistance. The optimum sample was prepared according to the best levels of each factor, and its morphology was examined by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy.