Measurement of Stresses Developed in Steady Laminar Shearing Flows of Viscoelastic Media

Abstract

The shearing stress and both normal stress differences are reported for three solutions of polyisobutylene in decalin. The ratio of the second normal stress difference to the first, (P22−P33)/(P11−P22), is seen to be negative and to vary between −0.1 and −0.4 under the conditions studied for these media. The statistical significance and the precision of these data is considered in some detail; the results are believed to be definitive at the error levels specified. Previous measurements of this normal stress ratio, which may be shown to be free of all the major known errors, are seen to have yielded the same sign as obtained herein, for similar fluids.