Viscoelastic,mechanical,dielectric and thermal properties of in situ reduced graphene oxide / epoxy nanocomposites

The present work focusses on the facile preparation of epoxy/reduced graphene oxide (Ep/G) nanocomposites via solvent assisted thermal reduction of graphene oxide (GO) within the epoxy matrix. This strategy enables to resolve the problem associated with the agglomeration of reduced graphene oxide in epoxy. Here, GO was dispersed in epoxy/diclorobenzene mixture, which, on subsequent heating facilitated in situ reduction followed by curing. The reduction of GO was confirmed using FTIR, Raman, XRD, EDX, TGA, FE-SEM and TEM analysis. The viscoelastic, mechanical, morphology, dielectric and thermal properties of epoxy nanocomposites with varying in situ reduced graphene oxide (G) content were systematically investigated. The DMA results revealed that storage modulus of the nanocomposites augmented substantially by 20.6 % for 0.5 wt. % of G (Ep/G-0.5) along with a significant positive shift by 40°C in the glass transition temperature (T_g). The cross-link density enhanced significantly for Ep/G-0.5 with the lowest coefficient of effectiveness (C) reflecting its reinforcing effect in epoxy. Ep/G-0.5 exhibited an improvement in tensile strength, Young’s modulus and impact strength by 30.7 % 48 % and 17.4 %, respectively. The fractured surface of the tensile specimen evidenced the uniform dispersion of G at 0.5 wt.% loading. The dielectric constant (ε') enhanced from 4.8 to 21.9 for Ep/G-3 at a frequency10³ Hz. A very low value (<0.5) of loss tangent (tan δ) was exhibited by all Ep/G nanocomposites at 10³ Hz, making it suitable for charge storage devices. The addition of G ameliorated the thermal stability of epoxy resin. Such a cost-effective technique for the preparation of epoxy/reduced graphene oxide nanocomposites is promising for multifarious applications in industries.