A nanocomposite is provided including nonspherical silica nanoparticles dispersed in a curable resin or a curing agent, where the nanocomposite contains less than 2% by weight solvent. A composite is also provided including from about 4 to 70 weight percent of nonspherical silica nanoparticles dispersed in a cured resin, and a filler embedded in the cured resin. 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 optionally a dispersant, a catalyst, a diluent, a surface treatment agent, and/or a curing agent, 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 nonspherical silica nanoparticles dispersed in the curable resin.