Fabrication of Spirocyclic Phosphazene Epoxy-Based Nanocomposites with Graphene via Exfoliation of Graphite Platelets and Thermal Curing for Enhancement of Mechanical and Conductive Properties

Nanocomposites of a spirocyclic phosphazene epoxy (SP-epoxy) resin with graphene were prepared through the exfoliation of graphite platelets and thermal curing process. Transmission electric microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy confirmed the chemical exfoliation and following thermal reduction for the graphene. The TEM observation also demonstrated that the reduced graphene oxide, as the single- and/or few-layered stacking sheets, was homogeneously dispersed in the SP-epoxy matrix. The presence of graphene improved both the tensile and flexural properties of the nanocomposites as a result of the great surface area of graphene sheets in contact with the matrix. These nanocomposites also achieved a considerable increase in glass transition temperature, thermal decomposition temperatures, and storage modulus. It is highly emphasized that the SP-epoxy/graphene nanocomposites also presented a low percolation threshold of 0.375 vol % and achieved high electrical conductivity at a volume fraction of graphene higher than 0.75 vol %.