Simultaneous Interfacial Rheology and Microstructure Measurement of Densely Aggregated Particle Laden Interfaces Using a Modified Double Wall Ring Interfacial Rheometer
Simultaneous Interfacial Rheology and Microstructure Measurement of Densely Aggregated Particle Laden Interfaces Using a Modified Double Wall Ring Interfacial Rheometer
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DOI：
10.1021/la502329s
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发表时间：
2014-08-19
期刊：
影响因子：
3.9
通讯作者：
Christopher, Gordon F.
中科院分区：
文献类型：
--
作者：
Barman, Sourav;Christopher, Gordon F.
随着颗粒稳定泡沫和Pickering乳液在工业上的广泛应用，对颗粒界面的研究大大增加，而颗粒稳定泡沫和Pickering乳液的整体流变性和稳定性高度依赖于颗粒界面的界面流变性，而界面流变性是界面微观结构的函数。要了解决定颗粒界面流变性的物理机制，需要将流变学与微观结构相关联。为了实现这一目标，对双壁环界面流变仪进行了改进，以实现实时、同时的界面可视化和剪切流变学测量。概述了该工具的发展，并在一个样本系统上演示了它提供新颖和独特测量的能力。该工具已被用来研究微观结构在三种表面浓度下密集堆积的聚集颗粒界面的稳定剪切流变学中的作用。通过流变学的考察和界面微观结构对剪切响应的分析，确定了界面从聚集态团簇破裂引起的剪切变薄到界面内滑移面屈服的转变。有趣的是，发现聚合接口在达到拥塞状态之前就转变为屈服状态。此外，当密实堆积时，这些体系经历了显著的剪切诱导有序。这些结果表明，这些界面的力学性质不是简单的堵塞或不堵塞，界面流变性与微观结构的关系可以为我们理解未来如何设计颗粒界面提供重要的启示。通过对流变学和微观结构的研究，现在已经了解了决定观察到的流变性的机制，并可以用来预测和控制界面的流变性。
The study of particle laden interfaces has increased significantly due to the increasing industrial use of particle stabilized foams and Pickering emulsions, whose bulk rheology and stability are highly dependent on particle laden interface's interfacial rheology, which is a function of interfacial microstructure. To understand the physical mechanisms that dictate interfacial rheology of particle laden interfaces requires correlating rheology to microstructure. To achieve this goal, a double wall ring interfacial rheometer has been modified to allow real time, simultaneous interfacial visualization and shear rheology measurements. The development of this tool is outlined, and its ability to provide novel and unique measurements is demonstrated on a sample system. This tool has been used to examine the role of microstructure on the steady shear rheology of densely packed, aggregated particle laden interfaces at three surface concentrations. Through examination of the rheology and analysis of interfacial microstructure response to shear, a transition from shear thinning due to aggregated cluster breakup to yielding at a slip plane within the interface has been identified. Interestingly, it is found that aggregated interfaces transition to yielding well before they reached a jammed state. Furthermore, these systems undergo significant shear induced order when densely packed. These results indicate that the mechanics of these interfaces are not simply jammed or unjammed and that the interfacial rheology relationship with microstructure can give us significant insight into understanding how to engineer particle laden interfaces in the future. By examining both rheology and microstructure, the mechanisms that dictate observed rheology are now understood and can be used to predict and control the rheology of the interface.