Evaluating the effective creep properties of graphene-reinforced polymer nanocomposites by a homogenization approach

Abstract

The creep modulus of graphene nanoplatelet (GNP)-reinforced epoxy nanocomposites is estimated using a homogenization approach based on the Mori-Tanaka micromechanical model. Formation of the agglomerated GNPs and existence of the interphase region between graphene nanoparticles and polymer matrix are considered in the micromechanical analysis. The predictions from micromechanical simulations show good agreement with the experimental data existing in the open literature. At high graphene content, the local agglomeration of GNPs and interfacial region must be considered to obtain acceptable estimations. Uniform dispersion of graphene nanoparticles into the epoxy nanocomposites is found to significantly enhance the creep modulus. At time 30 min, the addition of 0.1 vol% GNPs can increase the nanocomposite creep modulus about 31.6%. However, the GNP agglomeration presents worse efficiencies in improving the nanocomposite creep properties. The graphene/epoxy nanocomposites with thicker and stiffer interphases show higher creep moduli. Furthermore, the epoxy nanocomposites reinforced by the aligned GNPs exhibit much better creep properties than the randomly dispersed-reinforced epoxy nanocomposites. When the graphene volume fraction is 1%, the 30 min creep modulus of nanocomposite reinforced with aligned GNPs can be increased about 17% as compared to the randomly dispersed GNP-filled nanocomposite.