NSF: Fundamental Studies of Plasticity in Soft Glassy Materials

软玻璃状材料，如浆料、浆料、泡沫和乳剂，在自然界和工业中广泛存在。这些材料具有固有的无序微结构，类似于更传统玻璃中的无序原子配置。这些软玻璃杯在放置时表现为固体，但当施加足够大的压力时，会像液体一样流动，例如牙膏中就会发生这种情况。在工业加工和应用中，了解这些软材料的屈服和流动都是至关重要的。虽然有关于特定材料的经验知识，但关于其流动特性(称为流变学)的一般物理原理以及如何根据材料组成的知识来预测这些原理，人们知之甚少。爱丁堡大学和埃默里大学的这项合作旨在更好地了解软玻璃的微观结构与其对压力的宏观反应之间的关系。为此，我们将使用快速三维成像的良好特性的胶体系统在受控流动。此外，我们将成像样品的微观结构，同时使用流变仪测量其应力-应变状态。这些实验将使我们能够确定软玻璃材料流动中的一般微观特征，从而更好地全面了解这类材料的流变学。

Soft glassy materials, such as slurries, pastes, foams and emulsions, occur widespread in nature and industry. These materials have an inherently disordered microstructure, similar to the disordered atomic configuration in more traditional glasses. These soft glasses behave as solids when left to themselves, but will flow like a liquid when a sufficiently large stress is applied, as occurs for example in toothpaste. Understanding the yielding and flow of these soft materials is of crucial importance both during industrial processing as well as for applications. While there is empirical knowledge about specific materials, little is known about the generic physical principles underlying their flow properties (known as rheology ) and how to predict these from a knowledge of material composition. This collaboration between the University of Edinburgh and Emory University aims to better understand the relation between the microscopic structure of soft glasses and their macroscopic response to stress. To that end we will use fast three-dimensional imaging of well-characterized colloidal systems under controlled flow. In addition, we will image the samples micro-structure while simultaneously measuring their stress-strain state using a rheometer . These experiments will allow us to identify generic microscopic features in the flow of soft glassy materials, and therefore provide a better overall understanding of the rheology of this class of materials.