[10p-S401-1~15] 1.1 Interdisciplinary and General Physics

[10p-S401-6] Mechanism of shear thinning of ionic liquid under high shear rate

〇Tatsuya Yamada¹, Hiroshi Ushiyama¹, Syogo Tejima¹, Jun-ichi Fujita² (1.RIST, 2.Univ. of Tsukuba)

Keywords:Ionic liquid, shear thinning, Molecular dynamics simulation

Molecular Dynamics (MD) simulations show that Ionic Liquids (IL) occur shear thinning under high shear rate conditions (~10⁹ [1/s] < dγ/dt), however the mechanisms are not well known. This research proposes that “Shear thinning of IL is caused by the reduction of the height of the flow activation energy barrier ΔE by the large stress associated with a high shear rate condition”. To test the hypothesis, a 1-dimensional shear thinning model (1D-model) including two fitting parameters was constructed based on the hypothesis and the shear rate dependence of the viscosity was calculated using the model. As the result, the “shear rate vs viscosity” curve calculated by non-equilibrium all-atom MD simulations was matched with that calculated by 1D-model and the temperature dependence of shear thinning is also reproduced in the model. Further, principal component of ΔE was the electrostatic interactions between the net charges of cations and anions. Those results support the hypothesis strongly.