Non‐newtonian flow of dilute sodium carboxymethyl cellulose solutions at different ionic strengths and of dilute solutions of cellulose nitrate and polystyrene in moderately viscous solvents studied by capillary viscometry · Experimental results

The gradient dependence of viscosity has been studied for sodium carboxymethyl cellulose (NaCMC) (M̄ w = 0.91 · 10 6 , DS = 0.75) in aqueous solvents (0.01 M NaCl, 0.10 M NaCl, and 0.20 M NaCl), for two fractions of cellulose nitrate (CN) (M̄ w = 5.5·10 6 and 0.36 · 10 6 respectively) in diethyl adipate, (η 0 = 0.0304 P) and for polystyrene (M̄ w = 7.8 · 10 6 ) in the solvents toluene (η 0 = 0.00558 P) and α‐methyl naphthalene, (η 0 = 0.0283 P). The velocity gradient ranges covered are 1.5 – 120,000 sec −1 , 0.7 – 70,000 sec −1 , 0.8 – 33,000 sec −1 , and 0.6 – 34,000 sec −1 for the solvents toluene, water, diethyl adipate, and α‐methyl naphthalene respectively. For the polyelectrolyte (NaCMC) the H UGGINS ' constant k′ first decreases with increasing shear until at q ∼ 1,000 sec −1 k′ passes a flat minimum. For the nonionic macromolecules, k′ decreases with increasing shear, but more rapidly for higher solvent viscosities, until the value k′ = 0 is reached. It was possible to extrapolate the [η] vs. shear rate curves with simple, equilateral hyperbolas.