A process for making a silica-polyolefin composite. The process has the steps of (a) reacting silica particles and an alkyl halosilane in the presence of a solvent and a catalyst to form silane-functionalized silica particles and (b) reacting the silane-functionalized silica particles with a vinyl-terminated polyolefin. There are other processes for making a silica-polyolefin composites. There are other processes for making metal phosphate-polyolefin composites.