Rheologica Acta, Vol.59, No.11, 809-819, 2020
Analysis of the flow properties of a Herschel-Bulkley fluid using short back extrusion viscometry and considering time-dependent and stress growth behaviors
The recently proposed short back extrusion (SBE) method is an improved immersed-type BE method. A translational concentric cylinder rheometer is used. As the measurement position is inside the sample, the upflow in the annular space is smooth even over a short distance (5 to 15 mm). Measurement over a short distance decreases the amount of sample adhering to the plunger; this facilitates repeated measurements, as the removal of the adhering sample after each measurement is not needed. The rheometer analysis program can perform automated Newtonian, power-law, and Herschel-Bulkley flow analyses by introducing novel mathematical solutions and obtaining constitutive equations for the various flow types. Herschel-Bulkley fluids exhibit semisolid properties and thixotropic flow characteristics, specifically, stress growth or time-dependent behavior. Currently, SBE viscometry is the only available method to evaluate viscosity and yield stress simply and simultaneously and this study presented the results compared with rotational cone-plate viscometry.
Keywords:Short back extrusion;Stress growth;Yield stress;Herschel-Bulkley;Viscometry;Concentric cylinder