Materials World Network: Fundamental Studies of Plasticity in Soft Glassy Materials

软质材料，如浆料、膏体、泡沫和乳液，在化学工业中普遍存在。 这些材料在单独使用时通常表现为固体，但在施加足够大的应力时会像液体一样流动。 了解软材料的屈服和流动在这些材料的工业加工和处理过程中以及材料的塑性是要控制的特征的应用中至关重要。 虽然有关于特定材料的经验知识，但对其流动特性（“流变学”）的一般物理原理以及如何根据材料成分的知识预测这些原理知之甚少。 该项目旨在通过在受控流动下对特征良好的胶体系统进行快速三维成像，更好地了解微观结构与宏观应力响应之间的关系。 这些材料的微观结构和应力-应变状态的同时测量将使我们能够识别致密悬浮液流中的一般微观特征，从而更好地全面了解这类材料的流变学。 这项工作是与英国爱丁堡大学的Wilson Poon和Rut Besseling小组合作进行的。 这两个小组在使用模型软材料（如胶体糊剂、胶体凝胶和乳液）方面拥有广泛但互补的专业知识。 每个小组的工作人员将花很长时间直接与另一个小组合作，这将为他们未来的跨学科和国际团队合作做好准备。

Soft materials, such as slurries, pastes, foams and emulsion, are ubiquitous in the chemical industries. These materials often behave as solids when left to themselves, but will flow-like a liquid when a sufficiently large stress is applied. Understanding the yielding and flow of soft materials is of crucial importance during industrial processing and handling of these materials, as well as for applications where the plasticity of a material is a feature to be controlled. While there is empirical knowledge about specific materials, little is known about the generic physical principles underlying their flow properties ("rheology") and how to predict these from knowledge of material composition. This project aims to better understand the relation between microscopic structure and macroscopic response to stress by fast three-dimensional imaging of well-characterized colloidal systems under controlled flow. The simultaneous measurements of the microstructure and the stress-strain state of these materials will allow us to identify generic microscopic features in the flow of dense suspensions, and therefore provide a better overall understanding of the rheology of this class of materials. This work is in collaboration with the group of Wilson Poon and Rut Besseling at the University of Edinburgh, UK. The two groups have extensive but complementary expertise in working with model soft materials such as colloidal pastes, colloidal gels, and emulsions. Personnel from each group will spend extended periods of time working directly with the other group, which will prepare them well for future interdisciplinary and international teamwork.