The rheological properties of capillary suspensions, suspensions with small amounts of an added immiscible fluid, are dramatically altered with the addition of the secondary fluid. We investigate a capillary suspension to determine how the network ages and restructures at rest and under applied external shear deformation. The present work uses calcium carbonate suspended in silicone oil (11 % solids) with added water as a model system. Aging of capillary suspensions and their response to applied oscillatory shear is distinctly different from particulate gels dominated by the van der Waals forces. The suspensions dominated by the capillary force are very sensitive to oscillatory flow, with the linear viscoelastic regime ending at a deformation of only 0.1 % and demonstrating power-law aging behavior. This aging persists for long times at low deformations or for shorter times with a sudden decrease in the strength at higher deformations. This aging behavior suggests that the network is able to rearrange and even rupture. This same sensitivity is not demonstrated in shear flow where very high shear rates are required to rupture the agglomerates returning the apparent viscosity of capillary suspensions to the same viscosity as for the pure vdW suspension. A transitional region is also present at intermediate water contents wherein the material response depends very strongly on the type, strength, and duration of the external forcing.

中文翻译：

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毛细管悬浮液中的重组和老化

毛细管悬浮液、添加了少量不混溶流体的悬浮液的流变特性随着二次流体的添加而显着改变。我们研究了毛细管悬浮液，以确定网络在静止和施加的外部剪切变形下如何老化和重组。目前的工作使用悬浮在硅油（11% 固体）中的碳酸钙和添加的水作为模型系统。毛细管悬浮液的老化及其对施加的振荡剪切的响应与由范德华力主导的颗粒凝胶明显不同。由毛细力主导的悬浮液对振荡流动非常敏感，线性粘弹性状态以仅 0.1% 的变形结束，并表现出幂律老化行为。这种老化在低变形下会持续很长时间，或者在较高变形下强度突然降低的较短时间持续存在。这种老化行为表明网络能够重新排列甚至破裂。在剪切流中没有表现出相同的敏感性，在剪切流中需要非常高的剪切速率来破坏附聚物，使毛细管悬浮液的表观粘度恢复到与纯 vdW 悬浮液相同的粘度。在中间含水量处也存在过渡区域，其中材料响应非常强烈地取决于外力的类型、强度和持续时间。在剪切流中没有表现出相同的敏感性，在剪切流中需要非常高的剪切速率来破坏附聚物，使毛细管悬浮液的表观粘度恢复到与纯 vdW 悬浮液相同的粘度。在中间含水量处也存在过渡区域，其中材料响应非常强烈地取决于外力的类型、强度和持续时间。在剪切流中没有表现出相同的敏感性，在剪切流中需要非常高的剪切速率来破坏附聚物，使毛细管悬浮液的表观粘度恢复到与纯 vdW 悬浮液相同的粘度。在中间含水量处也存在过渡区域，其中材料响应非常强烈地取决于外力的类型、强度和持续时间。