Paper Number
PO10 

Session
Poster Session

Title
A sequence of physical processes in time-resolved powder rheology

Presentation Date and Time
October 23, 2019 (Wednesday) 6:30

Track / Room
Poster Session / Ballroom C on 4th floor

Authors (Click on name to view author profile)

  1. Donley, Gavin J. (University of Illinois at Urbana-Champaign, Department of Chemical and Biomolecular Engineering)
  2. Shetty, Abhishek (Anton Paar, Rheology Division)
  3. Rogers, Simon A. (University of Illinois at Urbana-Champaign, Department of Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Gavin J. Donley1, Abhishek Shetty2, and Simon A. Rogers1
1Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801; 2Rheology Division, Anton Paar, Ashland, VA 14850

Speaker / Presenter 
Donley, Gavin J.

Text of Abstract
The behavior of powders under flow is relevant to a wide range of industrial processes, from pharmaceuticals to additive manufacturing. As the flow properties of powders, which are dictated by complex inter-particle interactions, are very sensitive to small changes in environmental parameters such as air flow rate, temperature, and humidity, the ability to obtain accurate and meaningful rheological data has been challenging. Here, we demonstrate the viability of a rotational air-bearing rheometer with a powder flow cell that enables rotational and oscillatory testing of powders. The setup is augmented with a mass flow controller which allows oscillatory testing of powders from sub-fluidized to completely fluidized states. We perform large amplitude oscillatory shear (LAOS) on soda lime glass spheres using a range of air flow rates that act to soften the powders, and analyze the response with the recently-developed Sequence of Physical Processes (SPP) approach. We show that the powders behave as nearly ideal elastoplastic materials with air flow-rate-dependent yield stresses. By phenomenologically describing the responses as simple elastoplastic responses with a constant yield strain and modulus, we show how entire amplitude sweeps can be described with only a few material parameters.