Using Taguchi experimental design to reveal the impact of parameters affecting the abrasion resistance of sol–gel based UV curable nanocomposite films on polycarbonate

This work aims at studying the abrasion resistance of differently formulated organic–inorganic hybrid coatings prepared by sol–gel method. The organic phase contained UV curable urethane acrylate oligomers and monomers having different functionalities. The inorganic phase was composed of tetraethyl orthosilicate (TEOS) and 3-methacryloxy propyltrimethoxy silane (MEMO). Through a Taguchi experimental design, the impact of influencing parameters such as molar ratio of precursors, hydrolysis ratio (R), post-curing temperature, post-curing time and weight percentage of inorganic to organic part were investigated. Very high transparency of hybrid coatings indicated that nano sized inorganic phase had formed. MEMO could facilitate the connection of two phases, preventing macro phase separation. However, high levels of MEMO lead to ‘defect structure’ in silica network as well as to decreased transparency and mechanical properties. The optimum condition in which highly transparent films with great abrasion resistance occurred was observed at equimolar ratio of water to alkoxide and TEOS: MEMO ratio being unity. Statistical analysis revealed that thermal post-curing was not significantly important.