Reinforcing Graphene Oxide Nanoparticles to Enhance Viscoelastic Performance of Epoxy Nanocomposites.

Graphene, two-dimensional (2D) sheet of carbon structure, in its purest form has shown potential for application in the fields of electronics, semiconductor, sensing, energy, displays, biomedical engineering, etc. Graphene oxide (GO) is easier to synthesise than the pristine graphene, scores comparable in terms of mechanical strength, but lags in electrical and thermal conductivity. GO plays an important role in nano-composites for use in loading conditions requiring superior mechanical strength. GO is a suitable candidate as reinforcement due to its better solubility in the epoxy polymer, resulting in improved properties. The present work reports the reinforcement of graphene oxide in epoxy matrix to enhance visco-elastic properties of the E-GO nano-composite. GO was prepared by wet chemical oxidation method from graphite flakes that were used as precursor. The E-GO nano-composite samples were prepared by solution mixing method, without the use of any external stimulus to exclusively understand the effect of GO reinforcement. Dynamic mechanical characterisation of the fabricated E-GO nano-composites for the visco-elastic properties was carried out using nano-indentation technique. Storage modulus and loss modulus of the nano-composites were tested over the frequency range of 20-200 Hz. Tan-delta or loss function was calculated to characterise energy storage capacity of the nano-composite samples under the loading. Tandelta showed 12% improvement at 1 wt% of GO reinforcement in the nano-composite. Hardness of the nano-composites improved upto 10% with GO reinforcement. Epoxy-based aircraft repair applications require epoxy to deliver superior elastic properties and the present report verifies the improvement in elastic behaviour of epoxy with the addition of GO.