Influence of hexamethylenediamine functionalized graphene oxide on structural characteristics and properties of epoxy nanocomposites

Hexamethylene diamine grafted graphene oxide (AGO) was synthesized using graphene oxide (GO) and hexamethylene diamine (HMDA) via (i) amidation between the amine groups and carboxylic acid sites of GO and (ii) reactions between the amine and epoxy groups on the GO surface. Successful grafting of HMDA on the GO surface was confirmed using various characterization tools. Epoxy nanocomposites were fabricated by incorporating different loading amounts of chemically modified GO (AGO) using cast molding method. Incorporation of modified GO effectively enhanced the mechanical and flexural properties of epoxy nanocomposites compared to the pristine GO filled systems. Epoxy nanocomposite loaded with 1 wt% of pristine GO resulted in 20.4% increase in tensile strength values compared to the neat epoxy system, whereas tensile strength increased about 38.1% on loading 1 wt% modified GO (AGO). The flexural strength of the nanocomposites increased to about 13.1% on loading 1 wt% of pristine GO in comparison to neat epoxy, whereas 23.2% increment was observed when AGO was loaded into the epoxy matrix. Slight improvements in thermal stability and electrical conductivity were also achieved on loading modified GO in epoxy nanocomposites, when compared to pristine GO filled epoxy systems. Strong interfacial adhesions and fine dispersion of modified GO in epoxy nanocomposites through a local amine-rich environment resulted in better reinforcement in comparison to the pristine GO filled epoxy system. This was further confirmed by morphological characterization of the fractured surfaces of epoxy nanocomposites using scanning electron microscopy (SEM).