Abstract
The mechanical strengths of epoxy composites reinforced with silica nanospheres, unfunctionalised or functionalised with either amine or epoxy groups, increase up to a proportion of 5 wt.% of filler, as reflected in a study of the shear storage modulus carried out in dynamic mechanical analysis. This improvement is observed in both glassy and rubbery states, moderately affecting the glass transition temperature of the material. From this percentage of strengthening substance the mechanical properties begin to deteriorate, but keeping (up to 10 wt.% of strengthening material), a greater storage modulus in shear than that of the pristine epoxy resin. A trend can be discerned as the percentage of filler increases in the nanocomposite, where the materials strengthened with silica nanospheres functionalised with epoxy groups show better mechanical behaviour than the rest. To improve the mechanical properties in the systems, it is important to use an intermediate percentage of strengthening material (not much higher than 5–7 wt.%), the exact proportion depending on the type of strengthening substance.