Investigation and Modeling of the Electrical Conductivity of Graphene Nanoplatelets-Loaded Doped-Polypyrrole

Abstract

In this study, a hybrid of graphene nanoplatelets with a polypyrrole having 20 wt.% loading of carbon-black (HGPPy.CB20%), has been fabricated. The thermal stability, structural changes, morphology, and the electrical conductivity of the hybrids were investigated using thermogravimetric analyzer, differential scanning calorimeter, X-ray diffraction analyzer, scanning electron microscope, and laboratory electrical conductivity device. The morphology of the hybrid shows well dispersion of graphene nanoplatelets on the surface of the PPy.CB20% and the transformation of the gravel-like PPy.CB20% shape to compact spherical shape. Moreover, the hybrid's electrical conductivity measurements showed percolation threshold at 0.15 wt.% of the graphene nanoplatelets content and the curve is non-linear. The electrical conductivity data were analyzed by comparing different existing models (Weber, Clingerman and Taherian). The results show that Taherian and Clingerman models, which consider the aspect ratio, roundness, wettability, filler electrical conductivity, surface interaction, and volume fractions, closely described the experimental data. From these results, it is evident that Taherian and Clingerman models can be modified for better prediction of the hybrids electrical conductivity measurements. In addition, this study shows that graphene nanoplatelets are essential and have a significant influence on the modification of PPy.CB20% for energy storage applications.

Keywords: electrical conductivity; graphene; hybrid; models; percolation; polypyrrole.

Figure 1

Laboratory electrical conductivity measurement setup.

Figure 2

SEM graphs of (a) Gr and (b) $\mathrm{PPy}.{\mathrm{CB}}_{20\%}.$

Figure 3

SEM graphs of (a) $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%}$ 1:3 (b) $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%}$ 3:7 (c) $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%}$ 7:13.

Figure 4

Temperature of analysis of Gr and $\mathrm{PPy}.{\mathrm{CB}}_{20\%}$. W-PPy.CB_20% and W-Gr are the percentage weight curves. D-PPy.CB_20% and D-Gr are the derivatives curves.

Figure 5

The hybrids temperature analysis: (a–d) percentage weight curve of $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%}$ 1:3, $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%} 3:7$, $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%} 7:13$, $\mathrm{PPy}.{\mathrm{CB}}_{20\%}$ and (e–h) derivatives curve of $\mathrm{PPy}.{\mathrm{CB}}_{20\%}$, $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%}$ 1:3, $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%} 3:7$, $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%} 7:13$.

Figure 6

DSC thermograms for $\mathrm{PPy}.{\mathrm{CB}}_{20\%}$ and $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%}$ (a) $\mathrm{PPy}.{\mathrm{CB}}_{20\%}$ (b) $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%}$ 1:3 (c) $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%}$ 3:7 (d) $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%}$ 7:13.

Figure 7

XRD pattern of (a) Gr (b) $\mathrm{PPy}.{\mathrm{CB}}_{20\%}.$

Figure 8

Comparison of the $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%}$ structures.

Figure 9

The experimental electrical conductivity of the $\mathrm{HGPPy}.{\mathrm{CB}}_{20\%}.$

Figure 10

Comparison of experimental measurement with simplified Weber model (SWM).

Figure 11

Comparison of experimental measurements with MCM.

Figure 12

Comparison of experimental measurements with MTM.