Graphene-based structural adhesive to enhance adhesion performance

This paper proposes the design of a new graphene nano-modified formulation to enhance the mechanical performance of structural adhesives. Well-characterized graphene platelets, produced through an effective approach for bulk production and morphology control, were embedded at different contents inside an epoxy adhesive based on tetraglycidylmethylene dianiline (TGMDA). The adhesive formulations were used to manufacture bonded joints, according to ASTM 2095, to analyze the effect of graphene platelets on the tensile strength of the joints. The effect of incorporating graphene in the adherents was also considered. Epoxy adhesives filled with graphene at a concentration of 1 wt% significantly enhanced the mechanical behavior of the bonded joints. Only in the case of unfilled adherents, the inclusion of 4 wt% graphene did not have a significant effect on the mechanical performance. This is likely due to the agglomeration of nanofillers causing heterogeneity in large domains at the interface between adherents and adhesives. The effect of graphene incorporation in the adherents, acting on the chemical compatibility between adhesives and adherent surfaces, led to a considerable increase in tensile strength in comparison with the corresponding joints with unfilled adherents. This beneficial effect is most probably due to the cumulative effects of intermolecular interactions between the graphene platelets and resin networks.