Effect of Graphene Nano-Additives on the Local Mechanical Behavior of Derived Polymer Nanocomposites

What is it about?

In this study, indentation tests of graphene-based polymer nanocomposites were carried out to determine the local elastic mechanical properties. The samples consist of epoxy matrix with graphene additives. Additives were added at levels of 0% as a control, 0.5%, 1%, 2.5%, 5% and 10% by weight. The local elastic properties such as moduli and hardness were calculated. After each indentation, the prints were characterized using scanning electron microscopy (SEM). It seems that the local mechanical properties of nanocomposite samples were improved as the amount of nano-additives increased. Based on the curve displacement and surface imaging, we can conclude that the nano-additives influenced the overall plastic mechanical behavior of the samples. For simulating micro-indentation test, a finite element analysis model was developed using ABAQUS software and compared to experimental tests. Good correlation was observed.

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Why is it important?

Local mechanical properties of an epoxy matrix reinforced with graphene nanoparticles (NGP) were investigated using depth-sensing micro-indentation. The addition of low percentage weight of NGP was considered as part of a strategy to enhance the mechanical properties of the nanocomposites. The graphene additives were uniformly distributed into the epoxy matrix, forming a nanocomposite. The study focused on the effect of the concentration of NGPs on the mechanical performance. It was found that the addition of NGP to epoxy matrix reduces the indentation depth (δ) and increases the Young modulus (E), Stiffness (S) and hardness (H). Micro-indentation tools have provided a new method to evaluate the degree of dispersion of nano-additives and the local mechanical properties at the micrometric scale. The local mechanical properties can be considered representative of those of the bulk. This study shows that the indentation test could be an excellent technique in characterizing the mechanical properties of composites laminate reinforced with graphene nano-additives. It seems that the local mechanical properties of nanocomposite samples were improved as the amount of nano-additives increased. Based on the curve displacement and surface imaging, the influence of nano-additives on the overall plastic mechanical behavior is noticeable. A proper numerical model was developed for validating the experimental results. A small difference between two approaches was remarked and defined by the projected contact area and the graphene nano-additive distribution. It seems that graphene tends to improve the fracture toughness of composite and interfacial resistance.

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