Normal stress differences in liquid crystalline hydroxypropylcellulose solutions

Abstract

All three viscometric functions are investigated as a function of shear rate for lyotropic solutions of hydroxypropyl cellulose (HPC). Through the use of m-cresol as the solvent, it was possible to investigate liquid crystal solutions at lower polymer volume fractions than have previously been studied for HPC. We find no evidence of a three-region viscosity curve, as has been widely reported for HPC at higher polymer volume fractions. The first and second normal stress differences (N1 and N2, respectively) both change sign twice as the shear rate is varied.