Aminosilane-co-Graphene Oxide/Epoxy nanocomposite coating: An approach towards toughness and viscoelastic properties enhancement

Abstract

Graphene oxide (GO) nanoplatelets are synthesized via modified Hummer method. Then, GO is surface functionalized using (3-aminopropyl) triethoxysilane, i.e. APTES, to substitute its functionalities with primary amine groups. Chemical, structural and morphological analyses reveal that APTES molecules have successfully been grafted on the GO flakes, interlayer d-spacing in the stacks has increased, an intercalated/exfoliated morphology with smaller agglomerations has obtained and number of flakes in the stacks has been reduced. Subsequently, various concentrations, i.e. 0.25 %, 0.5 % and 1%, are impregnated into a low molecular weight Bisphenol-A liquid epoxy resin which is then cured by a polyamidoamine hardener. The effects of the nano fillers on mechanical characteristics of the cured epoxy films are investigated by universal tensile test, dynamic mechanical analysis and morphology assessment of the ruptured cross sectional area. The results show significant increases in elastic modulus (24 %), maximum stress (12 %), maximum strain (24 %) and work of fracture (69 %) for the nanocomposite containing 1 wt.% silane-modified GO compared to blank epoxy. DMA outcomes also show that highest Tg and maximized crosslinking density belongs to this sample. Fractured-surface morphology studies describe the mechanical properties enhancement. Such enhancement in mechanical properties empowers the prospective of this coating as a heavy-duty protective coating in various industries.