Single-point determination of intrinsic viscosity

Limitations on the use of the equations [η] = {2(ηsp − ln ηre1)}1/2/c and [η] = (ηsp + 3ln ηre1)/4c in determining intrinsic viscosity, [η], by a single point method have been pointed out. Inclusion of higher order terms in the series expansion for ln ηre1 introduces an additional term in the above equations which is negligible when the value of Huggins' constant, k′, is in the vicinity of 0.3–0.4. More accurate values for intrinsic viscosity calculated by a single point method can be obtained using these modified equations provided k′ can be estimated.