Universal frequency-dependent ac conductivity of conducting polymer   networks
  A model based on the aspect of the distribution of the length of conduction paths accessible for electric charge flow reproduces the universal power-law dispersive ac conductivity observed in polymer networks and, generally, in disordered matter. Power exponents larger than unity observed in some cases are physically acceptable within this model. A saturation high frequency region is also predicted, in agreement with experimental results. There does not exist a universal fractional power law (and is useless searching for a unique common critical exponent), but a qualitative universal behavior of the ac conductivity in disordered media. 
A. N. Papathanassiou, I. Sakellis and J. Grammatikakis