A comparative investigation of aminosilane/ethylene diamine-functionalized graphene epoxy nanocomposites with commercial and chemically reduced graphene: static and dynamic mechanical properties

Incorporation of nanosized fillers into polymers has created new composites by expanding the functions and applications while retaining the excellent engineering and processing flexibility inherent to polymers. Compared with traditional nanofillers, more recently, graphene has been increasingly preferred as a candidate for strengthening and/or functionalizing polymer nanocomposites. The easy synthetic methods, low cost, and non-toxicity of graphene make this material attractive for many technological applications. Herein, we discuss the synthesis of different types of graphene from graphite via graphene oxide reduction. Commercial graphene (CG) as well as the synthesized chemically reduced graphene (CRG) and chemically reduced silane-modified graphene (SMG) were characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and ultraviolet visible (UV-vis) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies. The results confirmed that the silane molecules were attached on the surface of graphene sheets. Simultaneously, most of residual oxygen-containing functional groups of GO were reduced and the sp(2)-hybridized structure of graphene was restored. The utilization of these graphene-based materials in the fabrication of epoxy nanocomposites with enhanced properties has been explored and compared with those of neat epoxy and CG/epoxy nanocomposites. Inclusion of 0.25 phr CRG and SMG in an epoxy resin showed 28% and 32% increases in tensile strength, and the corresponding fracture toughness displayed 67.6% and 66.3% increase respectively. The improved mechanical properties of SMG/epoxy nanocomposites might be due to the uniform dispersion of functionalized graphene and strong interfacial bonding between modified graphene and epoxy resin.