Ultrasonic dispersion of SiO 2 particles in glassy epoxy resin

In this work, ultrasonic waves generated by an ultrasonic horn were used to disperse nano- and micrometer SiO₂ particles into glassy epoxy resin. Many processing conditions, such as dispersion time, cooling, and material's volume, were varied systematically with an aim of achieving an optimum dispersion of particles. The glassy epoxy resin was reinforced by using spherical SiO₂ powders with diameters of 0.7 μm and 1.6 μm and volume fraction of 0–20%. Dog-bone-shaped specimens were fabricated and measured under uniaxial tension for determining the fundamental material properties. Experimental results revealed that (1) increasing dispersion time resulted in more homogeneous dispersion, but excessively long dispersion could not further improve the dispersion effect; (2) the influence of dispersion time to neat epoxy is negligible; and (3) fracture surface of glassy polymer is very smooth, which is a viscous flow process different from metals. Finally, ultrasonic wave has proved to be a good technique for effectively dispersing SiO₂ powders in glassy epoxy resin.