In this paper, the experimental and theoretical investigation of mechanical properties of functionally graded (FG) epoxy/graphene nanocomposites is presented. Samples were organized for uniform distribution (UD) through weight percentage of graphene nanoparticles (0, 0.5% w/w, 1% w/w, and 1.5% w/w) as well as for FG distribution. Four samples with different weight percentages of nano-graphene (pure, 0.5% w/w, 1% w/w, and 1.5% w/w) were used to make FG samples. The distribution of nanoparticles was studied through a scanning electron microscopy (SEM). This study showed that no signs of agglomerated particles were observed in the SEM image in uniform distribution. Also, SEM imaging was performed for the FG sample, which showed that the boundaries of the layers were completely interconnected and
that the distribution of nanoparticles was uniform and continuous from one surface to another. Then, the samples were subjected to tensile tests. The results of the tensile tests showed that the tensile modulus began to increase from 0 to 0.5 wt.% of nanographene and then decreased. For FG samples, the tensile modulus is commonly greater than the related values for the UD of graphene nanoparticles. The theoretical predictions of the elastic modulus for nanocomposites were made by three methods (Einstein, Mori-Tanaka, and Guth-Gold), then the experimental results were compared with the theory. In addition, for FG distribution, the samples were loaded transversely and the experimental deflection was obtained and the theoretical values calculated for the elastic modulus were compared with experimental ones. Also, the
comparison between UD and FG samples show that the FG sample has the lowest deflection compared to the samples with uniform distribution of nanoparticles.