Dense colloidal suspensions are processed in a wide variety of industries. Challenges for pumping suspensions and slurries at high concentrations include shear thickening and dilation, which can have deleterious consequences. These systems are shear sensitive close to the jamming point, meaning that a significant increase in high shear viscosity can be observed with just a few percent change in volume fractions. Therefore, accurate and rapid determination of the jamming point can greatly aid formulation. Typically, conventional rheometry identifies the jamming point by a time-consuming process, whereby multiple flow curves of suspensions of different volume fraction are measured and extrapolated to the volume fraction where the viscosity diverges. We present an alternative approach for rapid, one-step, experimental determination of the jamming point for aqueous suspensions. The procedure monitors the shear stress under constant shear stress or shear rate as the sample is dewatered using immobilization cell rheometry, until the viscosity diverges. The method is validated by comparing the results of this work with conventional rheometry for a model suspension. Then it is applied to examine the effect of grafting a short-chain polymer to particles, comprising an industrial suspension of silica-coated titania. Polymeric coating of the particles increases the jamming concentration and mitigates shear thickening, qualitatively consistent with predictions from simulations. Graphical Abstract A new method is designed to extract the jamming point of a suspension. The procedure monitors the effective viscosity under prescribed shear conditions as the suspension is dewatered using immobilization cell rheometry. The geometry moves down to accommodate solvent evaporation, until the viscosity diverges, and the jamming point is reached.

中文翻译：

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通过固定化细胞流变仪进行一步式原位干扰点测量

稠密的胶体悬浮液在各种行业中得到加工。泵送高浓度悬浮液和浆液的挑战包括剪切增稠和膨胀，这可能会产生有害的后果。这些系统对靠近堵塞点的剪切敏感，这意味着高剪切粘度显着增加，体积分数仅发生几个百分点的变化。因此，准确快速地确定干扰点可以极大地帮助制定。通常，传统的流变测定法通过耗时的过程来识别堵塞点，由此测量不同体积分数的悬浮液的多条流动曲线并将其外推到粘度发散的体积分数。我们提出了一种快速、一步、水悬浮液堵塞点的实验测定。当样品使用固定化细胞流变仪脱水时，该程序在恒定剪切应力或剪切速率下监测剪切应力，直到粘度发散。该方法通过将这项工作的结果与模型悬架的常规流变测量结果进行比较来验证。然后将其用于检查将短链聚合物接枝到颗粒上的效果，颗粒包括二氧化硅涂覆的二氧化钛的工业悬浮液。粒子的聚合物涂层增加了干扰浓度并减轻了剪切增稠，这与模拟的预测定性一致。图形摘要 设计了一种提取悬架干扰点的新方法。当悬浮液使用固定化细胞流变仪脱水时，该程序监测规定剪切条件下的有效粘度。几何形状向下移动以适应溶剂蒸发，直到粘度发散，并达到堵塞点。