Electrical conductivity of polypyrrole/expanded graphite composites prepared by chemical oxidation polymerization

With excellent electrical properties of polypyrrole (PPy)/expanded graphite (EG) composites have been synthesized by chemical oxidation polymerization. Morphology of the composites has been examined by scanning electron microscopy (SEM), the images reveal that the composites exhibit well dispersed “worms” graphite. The relationship between the morphology and electrical conductivity was studied by X-ray diffraction techniques (XRD), Fourier transform infrared (FT-IR) and four probes resistance tester, the results indicated that the percolation threshold of PPy/EG composites at room temperature was as low as 0.04 wt% and the conductivity of 108 S/cm was achieved for 0.2 wt% of EG. The low percolation threshold and well electrical conductivity are attributed to the large surface area, worm pore structure and uniform dispersion of the EG forming conducting bridge in PPy matrix.