Abstract: | 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 M n to the intrinsic viscosity extrapolated to zero shear rate. |