Conductance in Water-Poly(vinyl alcohol) Mixtures

The conductance of 0.02-0.10 N potassium chloride in poly(vinyl alcohol)-water mixtures at 25 degrees decreases by about 50% as the polymer content increases from zero to 20% by weight, while the bulk viscosity increases from 0.0089 to over 1000 poises. Further increases in polymer concentration transform the highly viscous liquid into an elastomeric solid, in which the conductance still remains relatively high; it decreases significantly only after the glass composition (75% polymer at 25 degrees ) is reached. The internal viscosity, which controls ionic mobility, was estimated from the conductance data: it ranges from 0.01 to about 0.14 over the range 0-55% polymer, similar to the viscosity of many ordinary liquids. Rates of diffusion-controlled processes involving small molecules in macromolecular media can, therefore, be expected to be similar to those in usual solution.