Is the yield stress of aqueous foam a well-defined quantity?
Is the yield stress of aqueous foam a well-defined quantity?
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水性泡沫的屈服应力是一个明确定义的量吗？
DOI：
10.1016/j.colsurfa.2005.01.025
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
R. Höhler
中科院分区：
文献类型：
--
作者：
F. Rouyer;S. Cohen;R. Höhler
量纲论证表明，对于给定的分散相体积分数，含水泡沫和乳液的屈服应力应与表面张力之比和长度尺度(如平均气泡半径)成比例。我们表明，来自文献和我们的实验的屈服应力数据仅在非常粗略的近似下遵循这种比例。我们提出了新的实验证据，阐明了剪切带在这一背景下的作用，并讨论了屈服应力相对于流动几何和实验技术变化的稳健性。最后，我们证明了用小幅度的弹性剪切模量法对振荡屈服应力数据进行标度时，得到了一条随分散相体积分数变化的主曲线。
Dimensional arguments suggest that the yield stress of aqueous foams and emulsions, for a given volume fraction of the dispersed phase, should scale as the ratio of surface tension and a length scale, such as the mean bubble radius. We show that yield stress data from the literature and from our experiments follow this scaling only in a very rough approximation. We present new experimental evidence that clarifies the role of shear banding in this context and we discuss the robustness of the yield stress with respect to changes of flow geometry and experimental technique. Finally, we show that scaling oscillatory yield stress data by the elastic shear modulus at small amplitude provides a master curve when plotted versus the volume fraction of the dispersed phase.