The dielectric increment of a carboxymethylcellulose as a function of the degree of ionization

The dielectric increment of a specimen of carboxymethylcellulose in aqueous solution has been studied as a function of pH. For the free acid a low increment was obtained which increased with increasing ionization (sodium salt). With excess sodium or hydrogen ions the increment decreased. Similarly there was a marked increase of the increment per gram per liter for the sodium salt with increasing dilution. The dielectic increments obtained for various salts of carboxymethylcellulose followed the order: Li+ > Na+ > NH4+ > K+ in agreement with the ion exchange affinities found previously for these ions (reversed order). The data have been interpreted along the lines of current theories for polyelectrolytes, by taking into consideration the net charge of the polyion, and the polyion‐counterion association under varying conditions.