Precision rotation viscometer with electrostatic restoring torque for the centipoise range

Abstract

AbstractA concentric cylinder rotation viscometer with conical ends was constructed for the measurement of shearing stresses from about 2 × 10−3 to 1.6 dyne‐cm.−2 with a precision of 0.3% at rates of shear from 0.2 to 40 sec.−1. The instrument is intended for the study of dilute high polymer and polyelectrolyte solutions. A stable “suspension” having a negligible frictional torque was obtained by freely floating the inner stationary cylinder in the sheared liquid under investigation. The restoring torque was applied by means of an electrostatic system. Preliminary measurements showed that aqueous solutions of polyvinyl alcohol (du Pont Elvanol 72–60) showed Newtonian behavior at concentrations from 10−2 to 2 × 10−3 g./ml.; aqueous solutions of methylcellulose (Dow Methocel 4000 cps.) of concentration ranging from 10−3 to 4 × 10−5 g./ml. exhibited structural viscosity below rates of shear of 5 sec.−1.