Silane functional effects on the rheology and abrasion resistance of transparent SiO2/UV-curable resin nano-composites

Transparent UV-curable nano-composite coatings consisting of nano-sized SiO2 and acrylate resin have been developed to improve the abrasion resistance of organic polymers. The nano-sized SiO2 particles were surface-modified using various amounts of 3-methacryloxypropyltrimethoxysilane (MEMO). The MEMO concentration effects on the theological behaviors, optical and abrasion resistance properties were investigated using a viscometer, FUR, UV-visible spectrophotometer. The results showed that the steric-hinderance established on the nano-sized SiO2 surface due to the grafted MEMO can effectively improve the dispersibility of nano-sized SiO2 in acrylate suspensions. The MEMO-modified nano-sized SiO2 in acrylate solutions at low and high solid concentrations exhibited Newtonian and shear thinning flow behaviors, respectively. Moreover, the maximum solid concentration was estimated to be 0.23. As the MEMO/SiO2 weight ratio increases from 0.2 to above 0.6, the abrasion resistance was significantly improved and the pencil hardness increased from 4H to 6H, which may be attributed to the complete MEMO coverage on the SiO2 surface, thereby enhancing the dispersion, compatibility, and cross-linking density between the MEMO-modified SiO2 particles and acrylate resin. (C) 2009 Elsevier B.V. All rights reserved.