Effects of graphene nanoplatelets dispersion on the mechanical properties of epoxy resin and carbon fiber laminated composites

Graphene-related materials (GRM) show great potential as reinforcement in polymeric matrices, offering enhanced physicochemical and mechanical properties. In the aerospace sector, reinforced composites are increasingly used for their superior mechanical attributes and design flexibility. Incorporating graphene nanoplatelets (GNP) into epoxy resin (ER) is a promising approach to enhance the resin’s fracture toughness. The effectiveness of these nanocomposites depends heavily on the dispersion of nanoparticles within the matrix. Therefore, this work aimed to produce nanocomposites based on ER and GNP by evaluating different mixing processes and assessing the influence of GNP content on the resin´s properties, to determine the optimal conditions for the incorporation GNP-ER as matrix to produce hybrid laminated composites with carbon fiber fabric. Characterization of GNP powder revealed its organization in regular nanoplatelet stacking patterns, exhibiting multilayers with few defects. The characterization of nanocomposites showed that ultrasonication dispersion improved the dispersion of GNP in the resin, reducing agglomerates and increasing homogeneity. Tensile tests demonstrated that ultrasonication led to an increase of approximately 14% in the ultimate tensile strength (UTS) and up to 46% in the deformation at the break of the nanocomposites. Carbon fibers/GNP-ER composites were produced by the hand lay-up process and exhibited a decrease in UTS with the addition of GNP, suggesting that GNP may have acted as stress concentrators or even modified the viscosity of the matrix, which may have hindered the matrix´s ability to penetrate the carbon fabric, thereby reducing the mechanical properties.