Foam Structure and Rheology

泡沫结构和流变学

• 批准号: 9623567
• 负责人: Douglas Durian
• 金额: $ 18.83万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-10-01 至 1999-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9623567&HistoricalAwards=false
• 关键词: Foam; Structure; Rheology

w:\awards\awards96\*.doc 9623567 Durian This project seeks to elucidate the nature of the random packing structures of bubbles in liquid-based foams and the consequences of such structures, their dynamics, and their time evolution, for the macroscopic rheological behavior. This included efforts in two main areas: (a) The propagation of light through foams by multiple-scattering and the use of this generic phenomenon as a structural probe, and (b) The influence of evolution and shear-induced structural rearrangements on linear shear rheology and time evolution. Special interest is in determining if a linear regime exists, if structural rearrangements can play a role equivalent to thermal fluctuations and hence be assigned a "temperature", and if flow can affect time evolution. Rheology measurements will be accomplished with a commercial device and also with a custom Couette-cell which allows simultaneous access for measurement of the bubble-packing structure and dynamics by multiple light scattering techniques. The fundamental understanding thus achieved may provide a framework for more complex systems where dense random packing and irreversible structural rearrangements dictate macroscopic behavior, such as dense emulsions, colloidal suspensions, and granular media. %%% Liquid-based foams consist of a large number of gas bubbles very closely packed together in a small amount of liquid, as familiar from everyday life. The proposed experiments are designed to help achieve a fundamental understanding of the important properties of these materials, namely their stability and flow behavior, in terms of their microscopic structure and composition. Little is yet known due to the fact that light is strongly scattered by the bubble interfaces, thus restricting visual observation of the bubble-packing structure to the surface bubbles. However, we have re cently developed new experimental techniques which take advantage of multiple light scattering and which reveal for the first time details of the packing structure and its behavior. The fundamental understanding achieved through use of these techniques may enable rational design of foaming-liquid formulations, foaming techniques, and anti-foaming agents. This could benefit diverse industries where foams are currently dealt with by trial-and-error: food, cosmetic, detergent, mining, petroleum, pulp & paper, paint & coating, textile, leather, polymer, and waste and water remediation. ***

w：\awards\awards96\*. doc 9623567 Durian 该项目旨在阐明液体基泡沫中气泡的随机堆积结构的性质，以及这种结构的后果，它们的动力学和它们的时间演化，对宏观流变行为的影响。这包括在两个主要领域的努力：（a）光通过泡沫的多重散射传播和使用这种一般现象作为结构探针，以及（B）进化的影响 剪切诱导的结构重排对线性剪切流变学和时间演化的影响。 特别感兴趣的是在确定是否存在一个线性政权，如果结构重排可以发挥作用相当于热波动，因此被分配到一个“温度”，如果流可以影响时间的演变。 流变学测量将使用商业设备以及定制的Couette池来完成，该定制的Couette池允许多个测量人员同时访问气泡填充结构和动力学测量。 光 散射 技术. 的 由此获得的基本理解可以为更复杂的系统提供框架，其中致密的随机堆积和不可逆的结构重排决定了宏观行为，例如致密乳液、胶体悬浮液和颗粒介质。 %%%液体基泡沫由大量紧密堆积在少量液体中的气泡组成，与日常生活中常见的一样。拟议的实验旨在帮助实现对这些材料的重要性质的基本理解，即它们的稳定性和流动行为，在它们的微观结构和组成方面。由于光被气泡界面强烈散射，因此限制了对表面气泡的气泡填充结构的视觉观察，因此知之甚少。然而，我们最近 开发了新的实验技术， 利用多重光散射，并首次揭示了包装结构及其行为的细节。根本 理解通过 使用 的 这些技术 可以 使设计合理 的 发泡液体配方、发泡技术和消泡剂。 这可能使目前通过试错法处理泡沫的各种行业受益：食品，化妆品，洗涤剂，采矿，石油，纸浆纸，油漆涂料，纺织品，皮革，聚合物以及废物和水处理。&& ***