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.