Processing of expanded graphite reinforced polymer nanocomposites

Nanocomposites consisting of anhydride cured epoxy resin matrix reinforced with expanded graphite (EG) with concentrations of 1–2 wt.% were fabricated. Processing techniques such as direct, sonication, shear, and combined sonication and shear mixing techniques were employed in the fabrication of nanocomposites. It was found that both sonication and shear mixing produced in situ nanosize graphite sheets from EG. However, the occurrence of X-ray diffraction (XRD) peaks at 2θ = 26.38° (d0 0 2 = 3.37 Å) irrespective of processing technique confirmed the presence of graphite nanosheets in multilayer rather than a single layer form. The mechanical behavior of the nanocomposites was investigated as a function of particle concentration and processing technique. It was found that EG reinforced nanocomposites showed higher elastic modulus than neat epoxy. However, nanocomposites prepared with the aid of shear mixing provided the best exfoliation and dispersion of graphite nanosheets and as a consequence, the best modulus enhancement over other processing techniques.