Densification-induced conductivity percolation in high-porosity pharmaceutical microcrystalline cellulose compacts

Abstract

The percolationtheory is established as a useful tool in the field of pharmaceutical materials science. It is shown that percolationtheory, developed for analyzing insulator–conductor transitions, can be applied to describe imperfect dc conduction in pharmaceutical microcrystalline cellulose during densification. The system, in fact, exactly reproduces the values of the percolation threshold and exponent estimated for a three-dimensional random continuum. Our data clearly show a crossover from a power-law percolationtheory region to a linear effective medium theory region at a cellulose porosity of ∼0.7.