Studies on carboxymethylcellulose: Conductivity measurements of solutions, 2

The conductivity behaviour of carboxymethylcellulose (CMC) solutions was studied using different types of neutralizing reagents (LiOH, NaOH, KOH); the following order of conductance of CMC solutions was observed: Li+ < Na+ < K+. This conductance behaviour of CMC solutions with respect to the size of counterions is explained qualitatively as well as quantitatively. Binding of Li+, Na+ and K+ ions onto the polymer molecule and the influence of the degree of substitution, ,DS, on the conductivity of CMC were also investigated. The conductivity of CMC solutions as well as the fraction of bound counterions increase with increasing DS, at a given degree of neutralization (α) for each type of counterion. The effect of DS on the polymer charge fraction, i/s, is in line with the counterion condensation phenomena of Oosawa. The results regarding the dependence of the equivalent conductance of the polyion, Δp, on DS are compared with literature data.