Electrical properties and stability of polypyrrole containing conducting polymer composites

Conducting polymer composites of polyethylene and polypyrrole (PE/PPy, polypropylene and polypyrrole (PP/PPy), and poly(methyl methacrylate) and polypyrrole (PMMA/PPy) were prepared by means of a chemical modification method, resulting in a network-like structure of polypyrrole embedded in the insulating polymer matrix. The content of polypyrrole determined by elemental analysis varied from 0.25 to 17 wt.%. Electrical conductivity of compression-moulded samples depends on the concentration of polypyrrole and reached values from 1 X 10(-11) to 1 S/cm. The morphology of the composites was investigated by low-voltage scanning electron microscopy (LVSEM). Potential contrast measurements as a function of the acceleration voltage were used to prove the perfection of the PPy network structure. The electrical transport mechanism in PP/PPy composite was studied. The data of the temperature dependence of conductivity were fitted following the function for a charge-energy-limited tunnelling (CELT) model. There is only a small drop in conductivity caused by annealing of PP/PPy composites in air at temperatures up to 80 degrees C. A stabilizing effect of PPy on thermal stability of polypropylene is shown by thermogravimetric analysis. The antistatic properties of PE/PPy and PMMA/PPy composites were demonstrated.