Incorporation of graphene oxide nanolayers into thermally stable hybrid composites of thermosetting resins by combination of curing and sol–gel reactions

Three different hybrid composites with high thermal stability and char residue were prepared from incorporation of tetraethyl orthosilicate (TEOS)-modified epoxy resin (MER), (3-glycidyloxypropyl) trimethoxysilane (GPTMS)-modified novolac resin (MNR), epoxidized novolac resin (ENR), and also furfuryl alcohol- and (3-aminopropyl) trimethoxysilane (APTMS)-modified graphene oxide (GFS) into silica/siloxane network by a sol–gel reaction. The first hybrid was composed from ENR, MNR, and GFS. The second type was prepared from MER, MNR, and GFS. The third type was prepared from MER, novolac resin, and GFS in the presence of triphenylphosphine (TPP). Results of FT-IR and XPS confirmed successful modification of epoxy and novolac resins and also functionalization of GO with furfuryl alcohol and APTMS. Results of TGA showed that GFS reaches to char residue of 37.3% at 600 °C. Char residues of 44.4, 44.0, and 34.2% were obtained for the first, second, and third hybrid composites without GFS loading. Addition of 1 wt% of GFS into the hybrid networks results in increase of char residues to 56.3, 50.0, and 34.7%, respectively. So, the first hybrid composite reaches to the highest char residue at 600 °C. These hybrid composites showed degradation temperature of 416.4, 434.5, and 424.8 °C.