PSI - Issue 25

J.M. Parente et al. / Procedia Structural Integrity 25 (2020) 282–293 J.M. Parente/ Structural Integrity Procedia 00 (2019) 000 – 000

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tions without compromising density, toughness or the manufacturing process (Giannelis 1996; Ling and He 2004 Saber-Samandari et al. 2007). Among the nanoparticles used, graphene is the most promising due to its excellent mechanical and electrical properties (Domun et al. 2015). It consists of one atom thick carbon honeycomb structure in a lattice formation (Kuilla et al. 2010), and this nano-reinforcement can be divided into three groups: graphene nanosheet (single layers of graphene), graphene nanoplatelets (several layers of graphene nanosheets connected by Van the Waals) and graphene oxide (graphene nanosheets with added oxy groups) (Parente et al. 2019). Fig. 1 shows their different structures and, consequently, different benefits are expected when added to polymeric resins. For example, graphene oxide contains oxy-type groups that promote better graphene-polymer interactions, and they are more appropriate for functionalization (Singh et al. 2016). On the other hand, graphene platelets have larger surface area when compared to graphene oxide or graphene nanosheets, due to its bigger dimensions, and higher graphene-polymer interactions are expected (Anwar et al. 2016). In this context, higher mechanical properties are obtained when they are added to polymeric materials (Atif et al. 2016), because graphene is a strong material, but they also prevent crack propagation, as shown in fig. 2 ( Metaxa et al. 2017). This last benefit is very important in terms of impact response and fatigue life.

Fig. 1. (a) Chemical structure of graphene nanosheet; (b) Chemical structure of graphene oxide; (c) Chemical structure of graphene nanoplatelets

Fig. 2. Scheme showing crack propagation and deflection in a polymeric resin reinforced with graphene.

Although most of the studies found in the open literature focus essentially on static characterization of graphene reinforced materials, there are also some works about fatigue performance of such materials. This phenomenon is very important, because failures originated by fatigue may have tragic consequences (especially in railways, aircraft, or process industries). Therefore, research on fatigue contribute to reduce the probability of accidents and disasters. In this context, this article provides an overview of the works available in the literature, in order to understand and