Hydrothermally resistant thermally reduced graphene oxide and multi-wall carbon nanotube based epoxy nanocomposites

This study is focused on the investigation of thermo-mechanical properties of an epoxy resin filled with thermally reduced graphene oxide (TRGO) and multi-wall carbon nanotubes (MWCNT) after exposure of samples to hot distilled water. Addition of low contents of TRGO and MWCNTs greatly reduces the water sorption capacity of the epoxy polymer and improves its resistance to hydrothermal ageing. The glassy and rubbery moduli of the neat epoxy decreased for about 20% and 80%, respectively, while TRGO-based epoxy filled with 0.3 wt.% of TRGO showed only 6% reduction of both moduli. Hydrothermal ageing resulted in an enormous drop in the glass transition temperature (Tg) of the neat epoxy, by about 90 °C, while the shift in Tg of the nanocomposites did not exceed 8 °C. After re-drying of samples, the position and shape of the peak was completely recovered for the nanocomposites. Irreversibility of water influence on the neat polymer appeared in the broadened and shifted glass transition region. The improvement of the thermo-mechanical properties of the neat epoxy from the addition of TRGO is higher than that achieved by incorporating MWCNTs. This trend is valid in both unexposed state and after hydrothermal ageing of the nanocomposites.