Abstract
Four kinds of silica sols in butyl acetate with different particle sizes were prepared and modified by vinyl triethoxysilane. The modified silica can be directly used to prepare solvent-borne acrylic-based polyurethane-nanosilica composites via in situ polymerization. It was found that the modified silica particles could be dispersed into polymer matrix while unmodified silica sol particles easily aggregated, but if the particle size was too small (e.g., <20 nm), even modified silica had a trend toward aggregation. Modified silica particles in acrylic resins had a slight increase in size in comparison with their original size. The modified particles had a high elemental Si content at the surfaces than the unmodified particles, both of them increased the Si content at the surfaces as the particle size of silica sol increased except for the very small size particles, accompanied by an increase in the roughness of the surface. Unmodified silica particles caused much rougher surfaces than modified silica particles due to aggregation. The abrasion resistance and tensile properties of acrylic-based polyurethane were improved by the silica particles, especially by the modified silica, due to the stronger interaction and better dispersion in the polymer matrix.
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