Physico-Mechanical and Dielectric Relaxation Spectroscopy of Fluoroelastomer Nanocomposites: Effects of Graphene Oxide Concentration and Frequency.

Graphene oxide (GO) nanoparticles have been used at different concentrations (1–5 wt%) to prepare fluoroelastomer (FKM) nanocomposites. The physico-mechanical features of FKM nanocomposites exhibit an increase in tensile strength, modulus, hardness and elongation at break decrease with increasing concentration of GO nanoparticles. This is due to the good distribution of GO in FKM rubber. The effect of GO concentration on dielectric performances which includes dielectric loss tangent (tan δ), real impedance, imaginary impedance and electrical conductivity were studied as a function of frequency range 10⁻² –10⁵ Hz. The intensity of tan δ peak of FKM nanocomposites has a gradual decrease with frequency as well as their peaks also shifts toward lower frequency region. Variation in spectra of real impedance reveal decreasing behavior with frequency and imaginary impedance characterizes the properties like diminished peak intensity for GO/FKM nanocomposites. The Nyquist plots show good semicircles that exhibit polarity with a single relaxation time. The extent of the GO concentration has a significant impact on the dielectric permittivity of the nanocomposites. Using the percolation theory, it has been determined how frequency affects electrical conductivity. The percolation phenomenon has been discussed using electrical conductivity of GO/FKM nanocomposites and found at 4 wt% GO concentration. [ABSTRACT FROM AUTHOR]