The effect of SiO2 filler content and its organic compatibility on thermal stability of epoxy resin

Thermal properties of the organic-inorganic bicontinuous nanocomposites prepared via in situ two-stage polymerization of various silanes, epoxy, and amine monomers are investigated, and the impact of filler content and its organic compatibility on thermal stability of these nanocomposites is studied. Two series of epoxy-silica nanocomposites, namely, EpSi-A and EpSi-B containing 0-20 wt% silica, are synthesized. An epoxy-silane coupling agent is employed to improve the organic compatibility of silica in EpSi-B nanocomposites. The composites synthesized via two-stage polymerization are characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric (TG) analysis. DSC and TG/differential thermogravimetric results reveal substantially high glass transition (T (g)) and excellent thermal stability of the bicontinuous nanocomposites as compared with pristine epoxy polymer. Both T (g) and thermal properties, however, considerably vary depending on the organic compatibility of the nanocomposites. Significantly higher decomposition temperatures are recorded in case of EpSi-B nanocomposites owing to the chemical links between the epoxy and silica phases. Kinetic studies also show relatively higher activation energies of pyrolysis for EpSi-B nanocomposites.