(58d) The Use of Modern Rheometers in Powder and Granular Media Measurements for Scientific and Industrial Purposes

Authors: 
Schütz, D., Anton Paar
Shetty, A., Anton Paar USA
Hartmann, K., Anton Paar Gmbh
Riedl, E., Anton Paar Gmbh
Modern Rheometers are usually equipped with high precision optical encoders and air bearings and a very Precise DC Motors and fast normal force sensors. Furthermore flexible programmable software allows complex and conditional measurements to be programmed by the user. A vast array of peripherals allows to re-equip the baseline instrument to the specific need of the measurement in question. These features allow gathering of novel data not accessible to traditional Powder characterization equipment such as:

Using high torque resolution (+- 10 nNm) as a means of distinguishing between very similar powders

Oscillatory experiments such as frequency or Amplitude analysis allow the exact state of fluidization to be determined even for group c powders

Characterizing extremely free flowing granular media through the high torque resolution and relating this to the angle of internal friction / tensile strenght

Creep Tests through the use of the precise control of radial velocity of the measurement system

Control of consolidation from the fluidized state to high normal strain: allowing to control the of the state of consolidation and therefore being able to simulate process conditions better

Simzultion of low gravity condition through the use of Fluidizing air

Direct apparent viscosity measurements in fluidized beds and the direct measurement of the stokes number

Temperature and Moisture Control within the instrument

These options allow us to directly simulate process conditions to serve both as a calibration tool for calculative approaches as well as a tool for analytical. All of the measurements above will be presented and discussed both as an analytical tool by itself but also as a an industrial example.

Lastly the the use of these devices with inertial rheology is discussed