Fig. 9 shows the effect of filler loading on the flexural strength, flexural modulus and Rockwell hardness of the epoxy composites. The flexural strength was found to decrease with increased WO3 filler size while it had little or no effect on flexural modulus. Similar results were reported by Park [21], who observed an increase in flexural strength with decreased particle size in silica-reinforced epoxy composites. However, Moloney et al. [22] reported a negligible effect of particle size on flexural modulus in their epoxy composites filled with silica.