Paper Number
SC24 

Session
Suspensions & Colloids

Title
LAOS response of the rigid-rod model in nematic regime

Presentation Date and Time
October 16, 2018 (Tuesday) 4:10

Track / Room
Track 1 / Galleria I

Authors (Click on name to view author profile)

  1. De Corato, Marco (Imperial College London, Chemical Engineering)
  2. Natale, Giovanniantonio (University of Calgary)

Author and Affiliation Lines (in printed abstract book)
Marco De Corato1 and Giovanniantonio Natale2
1Chemical Engineering, Imperial College London, London, United Kingdom; 2University of Calgary, Calgary, Canada

Speaker / Presenter 
Natale, Giovanniantonio

Text of Abstract
Nematic phase of rigid-rod molecules presents rheological complexities given the intrinsic anisotropy of the molecules and spatial variation of an average molecular orientation (director) in the bulk. The Doi-Hess rigid-rod1,2 model has been shown to predict correctly the rheological response and orientation dynamic of nematic phase. This microscopic model has been investigated in simple shear and elongational flow. In simple shear flow, the dynamic response was demonstrated to be quite complex and depending on the interplay between the intensity of the excluded volume potential and the applied shear flow different dynamics are obtained (log-rolling, wagging and tumbling regimes). Oscillatory shear flow is a model transient flow field which introduces a transient and periodic perturbation to the system. Recently, large amplitude oscillatory shear (LAOS) has attracted interest given the rich rheological response that is obtained. This enables more precise and complete characterization of the complex materials. However, the interpretation at the microstructural level of the LAOS response is still limited to specific systems. For the first time, we aim to investigate the response of the rigid-rod model in oscillatory shear flow. We perform numerical simulations of the Doi-Hess kinetic equation using Brownian dynamics and an expansion in spherical harmonics. The results show that the orientation tensor (second order moment of the orientation distribution) response for this system contains even and odds modes in the Fourier space. Finally, we attempt to link microstructural information to the rheological response for this system.

1 Hess, S. (1976). Zeitschrift für Naturforschung A, 31(9), 1034-1037.

2 Masao, D. (1981). Journal of Polymer Science: Polymer Physics Edition, 19, 243.