Steady State and Transient Shear Stress Measurements with Biconical Rheometer

摘要

A Biconical Rheometer, designed to operate at constant shear rate in the range of 0.0001 to 100/sec, is capable of determining the apparent viscosity as a function of time for polymer melts. An enclosed sample cavity eliminates the air-polymer interphase; thus, there is no polymer melt 'fracture' to limit the shear rate range. The instrument is equipped with a stiff torque transducer and a clutch-brake unit for the instantaneous shear application necessary in transient polymer response studies. Air suspension bearings make the instrument virtually frictionless and interchangeable torque transducers provide the capability for stress relaxation studies after cessation of flow. Transient and steady-state results for a family of narrow distribution polystyrenes are included to demonstrate the ability of the Rheometer. (Author)