GOALI: Collaborative Research: Non-invasive measurement of kinematics and rheology in a non-equilibrium drying complex fluid

涂料影响许多应用，包括消费品，医药，食品和工程应用，通常服务于三个目的之一：保护和延长产品的使用寿命，改善美观性，或增加新的功能。在流体膜涂层凝固过程中形成的小缺陷会损害涂层的最终功能。在单个汽车工厂中，喷漆占能源消耗的60%，而修补缺陷的成本可能超过1000万美元/年。很少有方法能够在干燥过程中对涂层性能进行无创跟踪。本项目的目标是发展用时间和空间分辨光学测量来测量干燥涂层的瞬态粘度和流量的能力。通过该项目获得的有关瞬态流变学如何影响流体流动的基本知识将适用于多种涂层制造工艺。该项目将对涂料设计和加工产生重大影响，有助于弥合学术界和工业界之间的差距，并包括与科学、技术、工程和数学社区的联系。本文的研究目的是测量干燥复合流体的瞬态流变学和运动学。传统的宏观流变技术需要在测量过程中与涂层进行物理接触（即该技术是侵入性的，并且改变了干燥），并且无法在空间上解决涂层内部的流变变化。该项目将通过非侵入性、高时间和空间分辨率的光学技术来测量模型复杂流体的时间和空间分辨率的流变和流动。具体而言，研究目标是：(1)测量不同粘度干燥薄膜流变学的空间依赖性；(2)确定并实现适合干燥粘弹性流体薄膜的对流校正方法；(3)测量配方和衬底角度对干燥粘弹性流体薄膜瞬态对流细胞结构及相关微结构形成的影响。关于~0.100 mm模型薄膜的拟议工作将适用于广泛的应用，并将补充工业合作伙伴PPG正在进行的工作。如果这项研究取得成功，将大大提高涂料的设计和加工的广泛应用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Coatings impact many applications, including consumer products, medicine, food, and engineering applications, typically serve one of three purposes: to protect and extend the life of a product, to improve aesthetics, or to add new functionality. Small defects that form during solidification of a fluid film coating can harm the ultimate functionality of the coating. In a single automotive plant, painting accounts for 60% of the energy consumption, and refinishing to repair defects can cost more than $10 million/year. There are few methods capable of non-invasive tracking of the coating properties during drying. The objective of this project is to develop the capability to measure the transient viscosity and flow of a drying coating with time- and space- resolved optical measurements. The underlying knowledge gained via this project in relation to how transient rheology affects fluid flow will be applicable to a multitude of coating manufacturing processes. The project will have significant impact on coatings design and processing, help to bridge the gap between academia and industry, and include outreach to the science, technology, engineering, and math communities.The research objective of this proposal is to measure the transient rheology and kinematics of a drying complex fluid. Traditional macroscopic rheological techniques require physical contact with the coating during the measurement (i.e. the technique is invasive and alters drying) and are unable to spatially resolve rheological changes within the coating. This project will be enabled by non-invasive, high temporal and spatial resolution optical techniques to measure the time- and space-resolved rheology and flow in model complex fluids. Specifically, the research goals are to (1) measure the spatial dependence of rheology in a drying thin film with varied viscosity, (2) to determine and implement a suitable method of convection correction for thin films of drying viscoelastic fluids, and (3) to measure the impact of formulation and substrate angle on the transient convection cell structure and related microstructure formation in thin films of drying viscoelastic fluids. The proposed work on model ~0.100 mm thin films will be applicable to a broad set of applications and will complement ongoing work the industrial partner, PPG. When successful, this research will significantly enhance the design and processing of coatings for a wide range of applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.