Shear Dependence of the Viscosity of PVA Solution
I. Measurements on the Low Shear Region and effect by the Concentration of the Solution
1959 Volume 16 Issue 174 Pages 579-583
Details
1959 Volume 16 Issue 174 Pages 579-583
Shear dependces of the viscosity of the polyvinylalcohol (PVA) solution were studied for the moderate concentrated solutions at 30°C.:(1) Inthe low shear region, the plots of the reduced viscosity, ηsp/c, vs. the shear rate, γ, are horizontal and the solutions seem to be Newtonian. This region decreases with increasing of the concentration and the molecular weight of PVA.(2) The limiting shear rate, γcril, under which the solutions can be regarded as Newtonian, is obtained for the various concentration and molecular weight. In the dilute solution, e. g. 0.5 g/100 cc, the solutions can be regarded as Newtonian under 400 sec-1 unless the molecular weight of PVA is very high.(3) The shear effect, -d (ηsp/c)/dγ, increases with the concentration and the molecular weight of PVA. The relations between the shear effect and the concentration are linear but the slope increases sharply at Ccrit, which is proportional to 1/[η] of PVA. This Ccrit is equal to the critical concentration, which was found in the study of the concentration dependences of the viscosity, η, and the apparent activation energy of flow, Eη, for the PVA water solutions.
