Measurement of Dynamic Shear Viscosity and Stiffness of Viscous Liquids by Means of Traveling Torsional Waves

Abstract

A short periodically repeated train of torsional waves is transmitted along a glass or metal cylindrical rod. After reflection from the free end, these waves are sent back to the quartz crystal which serves as both transmitter and receiver. The phase shift and added attenuation caused by immersing the rod in the test liquid are measured by means of a special balancing arrangement, and yield a calculation of the impedance presented to the rod surface. From an analysis of wave propagation both in the rod and in the liquid, one can calculate the characteristic shear impedance of the liquid, and the dynamic viscosity and stiffness. Data for polyisobutylene liquids with static viscosities up to 2000 poises are given for the frequency range 25–150 kc. High frequency data (5–25 mc) for the same liquids obtained by a method previously reported on (see reference 10(b)) are correlated to the present work. Some results for polypropylene, polyisoprene, polybutadiene, and polypropylene sebacate are also given.