Viscometric study of chitosan solutions in acetic acid/sodium acetate and acetic acid/sodium chloride

A viscometric study was carried out at 25 degrees C to assess the physical-chemical behavior in solution and the mean viscometric molar mass ((M) over bar (nu)) of chitosan solutions with different deacetylation degrees, in two solvent mixtures: medium 1-acetic acid 0.3 mol/L and sodium acetate 0.2 mol/L: and medium 2-acetic acid 0.1 mol/L and sodium chloride 0.2 mol/L. Different equations were employed, by graphical extrapolation, to calculate the intrinsic viscosities [eta] and the viscometric constants, to reveal the solvent's quality: Huggins (H), Kraemer (K) and Schulz-Blaschke (SB). For single-point determination, the equations used were SB, Solomon-Ciuta (SC) and Deb-Chanterjee (DC), resulting in a faster form of analysis. The values of-(M) over bar (nu), were calculated by applying the equation of Mark-Houwink-Sakurada. The SB and SC equations were most suitable for single-point determination of [eta] and -(M) over bar (nu) and the Schulz-Blachke constant (k(SB)), equal to 0.28, already utilized for various systems, can also be employed to analyze chitosan solutions under the conditions studied. (C) 2015 Elsevier Ltd. All rights reserved.