Preparation of silica-decorated graphite oxide and epoxy-modified phenolic resin composites

A multifunctional hybrid curing component (GSD) for epichlorohydrin-modified novolac resin (ENR) was synthesized via grafting poly(amidoamine) (PAMAM)-modified silica nanoparticles (SD) on graphene oxide (GO) using a ring opening reaction. SD and GSD, as two different curing components, were also used in different contents as reinforcing fillers of ENR matrix. Fourier-transform infrared spectroscopy and thermal gravimetric analysis (TGA) results proved amine-decoration of silica nanoparticles and also successful preparation of GSD. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy results were utilized to investigate structure of the SD and GSD multifunctional curing components and also the resulted composites. XRD pattern of GSD shows two peaks at 10.1 and 21.8 degrees which belong to characteristic peaks of GO and silica nanoparticles, respectively, with weak intensities due to grafting of SD on the GO surface. Thermal investigation of the prepared composites by TGA showed that curing ENR with higher contents of GSD was resulted in higher thermal properties. The ENR composite cured with 5 wt% of GSD presented the highest char residue of 20.5% among the other hybrid composites.