What sort of rheology information can I get from the capillary rheometer?
Shear viscosity is the main measure of resistance to flow and therefore affects real processes, especially when there are changes in temperature and flow rates. The most basic experiment performed on the capillary rheometer is a “viscosity flow curve” or “shear rate sweep”. The test sample is pushed by a piston driven at a defined speed through a capillary die and the pressure monitored above the die. The pressure builds up until an equilibrium condition is reached, at which point the pressure is recorded and the speed is changed to the subsequent measurement point. This process is repeated over a number of speeds, typically 5-10. The range of speeds is selected to correspond to the shear rate range of interest and normally covers more than 2 decades (>100 fold dynamic range) in a single test.
