Paper Number
SC45 

Session
Suspensions & Colloids

Title
A viscoelastic modification to the Modified Delaware Thixotropic Model (MDTM)

Presentation Date and Time
October 18, 2018 (Thursday) 11:15

Track / Room
Track 1 / Galleria I

Authors (Click on name to view author profile)

  1. Armstrong, Matthew J. (United States Military Academy, Chemistry and Life Science)
  2. Wagner, Norman J. (University of Delaware)
  3. Beris, Antony N. (University of Delaware, Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Matthew J. Armstrong1, Norman J. Wagner2, and Antony N. Beris2
1Chemistry and Life Science, United States Military Academy, West Point, NY 10996; 2Chemical and Biomolecular Engineering, University of Delaware, Newark, DE

Speaker / Presenter 
Armstrong, Matthew J.

Text of Abstract
Recent work using small angle neutron scattering under flow has identified the existence of a microstructure that is dependent on flow conditions [1,2] in soft colloidal systems. On the other hand, over the last twenty years or so, a large number of empirically based thixotropic, rheological models has been developed that involve, albeit phenomenologically, a single scalar structural parameter, lambda [3-6]. These models involve the combination of a lambda-dependent decomposition of the shear stress to an elastic and a viscous contribution with a relaxation-based evolution equation for lambda. The rich behavior of the soft colloidal systems is primarily due to the interaction of the structure and the hydrodynamic force and this can be particularly enhanced applied through in transient flow, and/or large amplitude oscillatory shear flow. Applying large amplitude oscillatory shear (LAOS), and other transient flow conditions to complex fluids induces rheological responses, that, with proper modeling, can be used to sensitively probe the underlying microstructure and its dynamics. We demonstrate this for several colloidal systems including thermoreversible gel, fumed silica, carbon black and human blood while using a newly developed semi-empirical, thixotropic master-equation, with a novel viscoelastic modification developed around a scalar internal structural parameter using the recently published Modified Delaware Thixotropic Model as a basis [3,4,5,6]. [1] C.R. Lopez-Barron, A.K. Gurnon, A.P.R. Eberle, L. Porcar, and N.J. Wagner. Physical Review 89, 042301 (2014), 1-11. [2] J. M. Kim. PhD thesis, University of Delaware, 2013. [3] J. Mewis and N. J. Wagner, Colloidal Suspension Rheology, Cambridge Univ. Press (2012). [4] P. de Souza Mendes and R. Thompson. Rheol. Acta (2013) 52:673-694. [5] A. Mujumbdar, A. N. Beris and A. B. Metzner. J. Non-Newtonian Fluid Mech. 102 (2002). [6] C.J. Dimitriou, R.H. Ewoldt and G.H. McKinley. J. Rheol. 571(1), (2013).