The gas phase SiO 2 /epoxy nanocomposites with enhanced mechanical and thermal properties

The mechanical and thermal properties of epoxy nanocomposites filled with 7–40 nm spherical silica particles were investigated as a function of silica loadings. Due to the ultrasonic dispersion and modification of the coupling agent, the silicon dioxide (SiO₂) nanoparticles were readily dispersed in the epoxy resin with light aggregation for the loading of up to 5 wt% as determined using a scanning electron microscope (SEM). The tensile test indicated that the tensile strength and elongation at break of the nanocomposites increased by up to 23% and 31%, respectively, compared with the neat epoxy resin. The glass transition temperatures of all the epoxy nanocomposites were higher than that of the neat epoxy resin for about 35–45°C, but did not show significant changes with an increase in the silica loading. The fracture surfaces were also observed using SEM, which showed evidence of the SiO₂ nanoparticle debonding.