  The modification of the ac conductivity and the complex permittivity of
conducting polypyrrole was monitored throughout a two years thermal aging at
343K. Reduction of the cross-over frequency is correlated with the degradation
of dc-conductivity, while the ac conductivity region corresponding to the
so-called 'universal' dielectric relaxation remains practically invariant
during the first year of ageing, which implies a collective co-operativity
among multiple degradation processes that yield a practically time-independent
effective disordered environment. A broad dielectric loss peak recorded in
fresh specimens splits into two distinct relaxations for intermediate stages of
the annealing process. The ageing-time evolution of the dc component and the
relaxations are qualitatively analysed and time constants are determined.
