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, Δ_p, on DS are compared with literature data.