Slit die Rheometer
The benefit of slit die rheometer is that the Bagley
correction is not required to obtain the true shear stress. Pressure is
measured along the slit geometry using up to three flush mounted pressure
transducers, which enables direct determination of the shear stress.
For equivalent polymer volumetric flow rates, the rectangular geometry
will yield lower maximum shear rates than those of a capillary, but consistent
with those expected in extrusion. It is a modular construction allowing
easy use of different slit die measuring geometries. The slit geometry
itself is machined into a changeable insert, meaning that only the insert
has to be changed if a variation in either slit height or width is required.
This construction allows great flexibility over slot dimension and thus
shear rate.
