Hao Bonan, Li Benke, Yu Wei
Advanced Rheology Institute, Department of Polymer Science and Engineering, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University, Shanghai 200240, P. R. China.
Langmuir. 2021 May 25;37(20):6208-6218. doi: 10.1021/acs.langmuir.1c00367. Epub 2021 May 12.
For pendular suspensions with particles in contact with immiscible secondary liquid bridges, the shear field significantly influences particle aggregates and networks. In this work, we study the structure of the pendular network and how the structure changes under large-amplitude-oscillatory shear. Using rheology and optical microscopy, we found unique network destruction followed by reconstruction with increasing strain. Two processes show different shear-field dependencies, strain-rate dependency for destruction and strain dependency for reconstruction. A nonequilibrium state diagram is constructed to show the phase behavior, where the critical particle concentration of sol-gel transition is dependent on the shear history and may depend on shear strain nonmonotonically. Two different mechanisms, shear-induced network breakdown at low strain and shear-induced agglomeration at high strain, are suggested to describe the nonmonotonic critical concentration under the upward strain sweep quantitatively.
对于颗粒与不混溶的二次液桥接触的摆式悬浮液，剪切场会显著影响颗粒聚集体和网络结构。在这项工作中，我们研究了摆式网络的结构以及在大振幅振荡剪切作用下结构如何变化。通过流变学和光学显微镜，我们发现随着应变增加，网络会经历独特的破坏然后重建过程。这两个过程表现出不同的剪切场依赖性，破坏过程依赖于应变率，重建过程依赖于应变。构建了一个非平衡状态图来展示相行为，其中溶胶 - 凝胶转变的临界颗粒浓度取决于剪切历史，并且可能非单调地依赖于剪切应变。提出了两种不同的机制，即低应变下的剪切诱导网络破裂和高应变下的剪切诱导团聚，以定量描述向上应变扫描下的非单调临界浓度。
