  We performed dielectric spectroscopy on polypyrrole near the metal-insulator
transition (MIT) down to 2 K. We evaluate the dependence of the plasma
frequency and the scattering time (t) on the distance to the MIT, characterized
by the Fermi-level relative to the band-edge of extended states, E_F-E_c.
Especially the strong decrease of t with increasing E_F-E_c is in conflict with
the usually applied models for the MIT. Although morphology and disorder are
important, the MIT is Mott-Hubbard-like being dominated by the competition of
interchain charge transfer and electronic correlation.
