Determination of intrinsic viscosity from one-point measurements

A method is described by means of which reliable intrinsic viscosities, [η], can be obtained for a polymer–solvent system from viscosities determined at only one concentration. The method involves, first, the preparation for one sample of the polymer of an ηsp/C and ln ηr/C vs. C plot. The ratio of the slopes of these two curves yields then a parameter γ which is independent of molecular weight, and which allows single point [η] determinations on samples of the polymer at any other molecular weight, whether homogeneous or not. Results are presented to show that the method described yields [η]'s in good agreement with those obtained in the usual manner from multipoint viscosity measurements.