Effects of Moisture and High Electric Fields on Conductivity in Alkali‐Halide‐Doped Cellulose Acetate

Several problems associated with ionic conduction in amorphous hydrophilic polymers have been investigated from a theoretical point of view and then discussed in the light of experiments with alkali‐halide‐doped cellulose 2.5 acetate. The main ideas emphasized are: (1) The major effects of moisture on conductivity σ in this class of polymers are to increase the dielectric constant e′ and therefore the concentration of ions by reducing the effective dissociation energy from its maximum U0′ (≈ 140 kcal/mole) to a lower value ≈U0′/e′ such that σ≈σ1exp(−U0′/2RTe′), where σ1 depends on the square root of salt concentration n0; and (2) departures from Ohm's law in high fields E would occur as a result of activation barrier perturbation even in the absence of thermal and chemical effects. The above equation for σ was checked by starting with ``dry'' disks of CA and simultaneously measuring e′ and σ (dc) after periods of moisture sorption. The evidence suggests that the micro‐ and macroscopic values for e′ are pr...