An insight into thermal improvement of epoxy resin by nanohybrid formation from resin, graphene, and silica network

Three well-tuned procedures were used for thermal improvement of epoxy resin (E). Accordingly, graphene xerogel (GX) was used as nanofiller in the matrix of E. Additionally, (3-isocyanatopropyl)triethoxysilanemodified E (IE) or TEOS oligomer-modified E (TE) was incorporated into a hybrid structure of graphenecontaining silica/siloxane network (IEGX or TEGX samples). For this purpose, a bifunctional silane coupling agent of 1,1 -(hexane-1,6-diyl)bis(3-(3-(trimethoxysilyl)propyl)urea) (HDBTMSPU) was synthesized by reaction between a hexamethylene diisocyanate and two (3-aminopropyl)trimethoxysilane molecules. GX was obtained by incorporation of HDBTMSPU-modified graphene oxide (FGO) into xerogel structure by using HDBTMSPU and tetraethyl orthosilicate (TEOS). Modified resins, FGO, HDBTMSPU, and TEOS were also used in preparation of hybrid products. Thermal stability and char residue of the three composites were compared. TGA results showed that the hybrid of IE, FGO, and silica/siloxane network shows higher thermal properties. Char residue is increased by 16.93% by loading of only 1 wt% of FGO in this hybrid product