Mechanical properties of dynamically disordered networks

Abstract

Ionic motion in polymeric ionic conductors has been recently described in the framework of dynamic percolation theory (DPT) or, more generally, dynamic disorder hopping (DDH). In these models the polymer network above the glass transition is modelled as a random bond network in which the random bond distribution evolves in time with rate characteristic to the polymer motion. The present paper deals with the mechanical properties of such networks. We present a simple analysis of the viscosity of such dynamically disordered networks, thus relating a characteristic network relaxation time to the local (microscopic) viscosity of the polymer. If the same time is assumed to govern ionic transport, we obtain a relation between the ionic diffusion rate and the polymer viscosity. Estimates of the ionic diffusion based on this model are consistent with experimental observations.