An evaluation of an alternative method for determination of intrinsic viscosities.

Abstract

The intrinsic viscosity obtained from measurements of dilute solution viscosities is often used to determine the average molecular weight and chain dimensions of a polymer as well as the interaction between the polymer and the solvent. Although the measurement of a solution viscosity is a simple task, the evaluation of the intrinsic viscosity is subject to considerable inaccuracies and error magnifications. This is due to the fact that traditional methods for determination of intrinsic viscosities rely on extrapolations beyond the range of the experimental data. Many research efforts have focused on improving the extrapolations by refining the theoretical expressions associated with these extrapolations. In this work, an alternative method developed in this laboratory for determination of intrinsic viscosities is subjected to further evaluation using three different aqueous dilute polyacrylamide solutions. This alternative method does not involve an extrapolation and therefore does not depend on theoretical expressions. A comparison between the results obtained by the traditional methods and the new alternative method demonstrates the effectiveness of the new method in overcoming the difficulties of the former methods.