Understanding of Leading-Edge Protection Performance Using Nano-Silicates for Modification

Leading edge erosion caused by raindrop impact is a key problem that needs to be overcome in the wind energy sector. Solutions up to date have not proved suitable, failing prematurely in their lifecycle at a cost to the wind industry. Failure mechanisms for rain erosion are not well understood, particularly the elastic and viscous polymer properties at the resulting high strain rates (10⁶ - 10⁹ Hz) of raindrop impacts. The effect of the inclusion of glycidyl polyhedral oligomeric silsesquioxane nanoparticles into a commercial polyurethane coating system was studied using nanoindentation and dynamic mechanical thermal analysis (DMTA). Results show that the inclusion of POSS improves damping, providing an alternative mechanism for energy dissipation without variation of T_g and minimal loss of stiffness. This presents a way of modifying current coating systems through the incorporation of POSS. Nanoindentation obtained previously unreported properties of the coating system (hardness, modulus and short-term recovery) and highlighted a correlation between loading rate and a reduction of short-term recovery. Nanoindentation was difficult for the modified leading-edge protection (LEP) samples as two phases were formed resulting in large standard deviations. DMTA results show modification of the LEP increases damping at lower temperature ranges introducing an additional mechanism of dissipating energy. Additionally, sweep data show an increase in elasticity at higher frequencies on the modified samples. (paper)