摘要
A series of“guava-like”silica/polyacrylate nanocomposite particles with close silica content and different grafting degrees were prepared via mini-emulsion polymerization using 3-(trimethoxysilyl)propyl methacrylate(TSPM)modified silica/acrylate dispersion.The silica/polyacrylate composite particles were melt-mixed with unfilled polyacrylate(PA)resin to prepare corresponding silica/polyacrylate molded composites and the dispersion mechanism of these silica particles from the“guava-like”composite particles into polyacrylate matrix was studied.It was calculated that about 110 silica particles were accumulated in the bulk of every silica/polyacrylate composite latex particle.Both the solubility tests of silica/polyacrylate composite latex particles in tetrahydrofuran(THF)and the section transmission electron microscope(TEM)micrographs of silica/polyacrylate molded composites indicated that the grafting degree of silica particles played a crucial role in the dispersion of silica/polyacrylate composite particles into the polyacrylate matrix.When the grafting degree of polyacrylate onto silica was in a moderate range(ca.20%-70%),almost all of silica particles in these“guava-like”composite particles were dispersed into the polyacrylate matrix in a primaryparticle-level.However,at a lower grafting degree,massive silica aggregations were found in molded composites because of the lack of steric protection.At a greater grafting degree(i.e.,200%),a cross-linked network was formed in the silica/polyacrylate composite particles,which prevented the dispersion of composite particles in THF and polyacrylate matrix as primary particles.
