The rheological response of dilute solutions of high molecular weight polyacrylamides at low shear rates has been measured using a capillary viscometer that provided for a fivefold variation in shear rate at each concentration. The non-Newtonian effects were found to be significant for polyacrylamides with number-average molecular weights exceeding 106. The molecular weight average–intrinsic viscosity relationship most widely used in the literature, [η] = 6.80 × 10−4M, was found to be valid when [η] was measured at high shear rates where the polymer solutions approached Newtonian behavior. A new relationship was developed relating Mn to the intrinsic viscosity extrapolated to zero shear rate.
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Shawki et al. (1979) studied this question.