A nanocomposite is provided including silica nanoparticles and a dispersant dispersed in a curable resin or a curing agent, where the nanocomposite contains less than 2% by weight solvent. The silica nanoparticles include nonspherical silica nanoparticles and/or spherical pyrogenic silica nanoparticles. A composite is also provided including from about 4 to 70 weight percent of silica nanoparticles, and a dispersant, dispersed in a cured resin, and a filler embedded in the cured resin. Optionally, the composite further contains a curing agent. Further, a method of preparing a nanoparticle-containing curable resin system is provided including mixing from 10 to 70 weight percent of aggregated silica nanoparticles with a curable resin and a dispersant to form a mixture. The mixture contains less than 2% by weight solvent. The method also includes milling the mixture in an immersion mill containing milling media to form a milled resin system including silica nanoparticles dispersed in the curable resin.