Non‐N EWTONIAN flow of dilute ethyl acetate solutions of high molecular weight cellulose nitrate studied by capillary viscosimetry

The gradient dependence of viscosity has been studied for five fractions of cellulose nitrate (around 13.7% N) in the molecular weight region 0.36–5.5·106. The velocity gradient range covered is 0.5 to 150,000 sec−1. The slope of the ηsp/c vs. concentration curves decreases with increasing gradient but more rapidly for higher molecular weights. The gradient at which this slope becomes zero increases with decreasing molecular weight. For all fractions it was easy to extrapolate the [η] vs. shear rate curves with simple, equilateral hyperbolas. [η]∞ may be considered to be proportional to [η]0 according to the relation [η]∞ = 0.13 [η]0. The experimental results are viewed in the light of various theories based on anisotropy of hydrodynamic interaction, rigidity of the macromolecular coil, and nonuniform expansion of the macromolecular coil.