Quantitative investigation of convective flows in drying polymer films using 3D micro particle tracking velocimetry

使用 3D 微粒跟踪测速技术定量研究干燥聚合物薄膜中的对流

• 批准号: 444945948
• 负责人: Professor Dr.-Ing. Wilhelm Schabel
• 金额: --
• 依托单位: Bereich Thin Film Technology
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/444945948?language=en
• 关键词: Quantitative; investigation; convective; flows; drying

Thin, liquid-processed polymer films are an important component of many innovative products. Prominent examples are varnishes, optical films, organic light-emitting diodes or printed biosensors. The drying of such films often leads to unwanted layer thickness inhomogeneity and a deformation of the free surface, which has a considerable influence on the quality of the products. These effects can be attributed to surface-tension driven convective flow, so-called Marangoni convection, which is induced by locally inhomogeneous solvent evaporation. To increase the surface quality, it is necessary to avoid or at least reduce these flows. In order to investigate this phenomenon, not only an analysis of the deformations of the free surface, but also the knowledge of the flows in the film during the process is essential. In several very good research projects, analytical solutions and numerical simulations for the description of thermally induced convection have already been developed. In the context of film drying, however, other phenomena occur which have not been subject of research efforts so far. In addition to temperature effects, the solvent content decreases continuously during drying, which additionally influences the formation of surface tension gradients and convective flows and leads to a solidification of the already deformed film surface. These coupled phenomena have to be considered simultaneously during drying. To the best of our knowledge, no relevant work has been published on this subject in the literature.With the proposed research project, we aim to close this gap by experimental, quantitative investigations of solutal Marangoni flows induced by concentration gradients using 3D micro particle tracking velocimetry. In addition, the determination of corresponding stability limits will contribute to a significant gain of knowledge in this field of research.

薄的液体处理聚合物膜是许多创新产品的重要组成部分。突出的例子是清漆，光膜，有机发光二极管或印刷生物传感器。这种膜的干燥通常会导致不良层厚度不均匀性和自由表面的变形，这对产品的质量产生了很大影响。这些效果可以归因于表面张力驱动的对流流，即所谓的Marangoni对流，该对流是由局部不均匀溶剂蒸发引起的。为了提高表面质量，有必要避免或至少减少这些流量。为了研究这种现象，不仅是对自由表面变形的分析，而且在过程中胶片中的流量知识也是必不可少的。在几个非常好的研究项目中，已经开发了用于热诱导对流的分析解决方案和数值模拟。然而，在膜干燥的背景下，到目前为止，发生其他现象尚未进行研究工作。除了温度效应外，在干燥过程中，溶剂含量还连续降低，这还影响了表面张力梯度和对流流的形成，并导致已经变形的膜表面的凝固。在干燥过程中，必须同时考虑这些耦合现象。据我们所知，在文献中尚未就此主题发表相关的工作。根据拟议的研究项目，我们旨在通过使用3D微粒粒子跟踪赛车来浓度的浓度梯度来缩小对液溶质marangoni流的实验性定量研究。此外，确定相应的稳定性极限将有助于在这一研究领域的知识中获得大量知识。