Role of particle orientational order during shear thickening in suspensions of colloidal rods
Role of particle orientational order during shear thickening in suspensions of colloidal rods
复制标题
胶体棒悬浮液剪切增稠过程中颗粒取向顺序的作用
DOI：
10.1103/physreve.101.040601
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发表时间：
2020
影响因子：
2.4
通讯作者：
Ganapathy, Rajesh
中科院分区：
文献类型：
--
作者：
Rathee, Vikram;Arora, Srishti;Blair, Daniel L.;Urbach, Jeffrey S.;Sood, A. K.;Ganapathy, Rajesh
在恒定的剪切应力和/或剪切速率下，稠密的各向异性胶体悬浮液的流变性通常表现出不稳定的流动。同时使用高分辨率共聚焦显微镜和流变学，我们发现，由于剪切流和颗粒取向之间的强耦合的时间行为出现。在较小的外加应力下，杆的取向围绕流动方向波动。在较高的应力下，当流动和棒取向之间的角度达到临界值时，观察到向间歇性无序状态的转变。这种无序状态与剪切速率的瞬时下降和粘度的增加有关。同时可视化的边界应力和取向表明，无序的区域导致在边界处的非均匀应力和正的法向力，表明系统的形成跨越无序的颗粒接触网络。
Rheology of dense anisotropic colloidal suspensions often exhibits unsteady flow at constant imposed shear stress and/or shear rate. Using simultaneous high-resolution confocal microscopy and rheology, we find that the temporal behavior arises due to a strong coupling between shear flow and particle orientation. At smaller applied stresses, the orientation of rods fluctuates around the flow direction. A transition to an intermittent disordered state is observed at higher stresses when the angle between the flow and the rod orientation reaches a critical value. This disordered state is associated with transient drop in shear rate and an increase in viscosity. Simultaneous visualization of boundary stresses and orientation shows that the disordered regions lead to heterogeneous stresses and positive normal forces at the boundary, indicating the formation of systems spanning disordered particle contact networks.