3D microfluidics for extensional rheometry

用于拉伸流变测量的 3D 微流体

基本信息

批准号：
21K03884
负责人：
HAWARD Simon
金额：
$ 2.5万
依托单位：
Okinawa Institute of Science and Technology Graduate University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2021
资助国家：
日本
起止时间：
2021-04-01 至 2024-03-31
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-21K03884/
关键词：
extensional flow microfluidics rheology polymer solution viscosity viscoelastic fluid viscoelasticity flow instability

项目摘要

In FY2022, experiments were completed measuring the pressure drop and velocity field for viscoelastic polyacrylamide solutions (at dilute concentrations of 0.005 to 0.04 wt%) in a planar extensional flow device. Pressure drop and velocity field measurements have also been completed in the new uniaxial and biaxial extensional flow device developed during FY2021.A new data analysis has been developed to estimate the extensional viscosity of Newtonian and viscoelastic fluids. This ensures that the expected (constant) extensional viscosity is obtained for Newtonian fluid, and also for the polymer solutions at small flow rates. At high flow rates the extensional viscosity of the polymer solutions increases up to a plateau value that depends on the mode of extension. For the dilute solutions tested, the plateau values in uniaxial and planar extension are equal to each other and double that found for biaxial extension. This is in agreement with the finitely-extensible non-linear elastic dumbbell model, which is often used to describe such fluids in theory. Two journal papers have been prepared based on the work conducted so far in FY2021 and FY2022, which are both currently under review in the Journal of Rheology.Furthermore, experiments with viscoelastic polymer solutions revealed some interesting instability phenomena at high flow rates, which are worthy of a more detailed investigation. Our new data analysis method for estimation of the extensional viscosity also merits some additional experimental verification. These topics will be the focus of research in FY2023.

在2022财年，在平面扩展流动装置中，完成了粘弹性聚丙烯酰胺溶液的压降和速度场（以0.005至0.04 wt％）完成的实验。在FY2021期间开发的新单轴和双轴延伸流动装置中，已开发了一种新的数据分析，以估算牛顿和粘弹性流体的延伸粘度。这确保了牛顿流体以及以较小的流速的聚合物溶液的预期（恒定）伸展粘度。在高流速下，聚合物溶液的延伸粘度增加到了取决于延伸方式的高原值。对于所测试的稀释溶液，单轴和平面延伸中的高原值彼此等于彼此，并且是双轴延伸的两倍。这与有限延伸的非线性弹性哑铃模型一致，该模型通常用于描述理论上的这种流体。根据迄今为止在2021财年和FY2022中进行的工作准备了两篇期刊论文，这些论文目前都在《流变学杂志》中进行了审查。FURTHERMORE进行了粘弹性聚合物解决方案的实验，揭示了一些有趣的不稳定现象，这些现象是值得的，这些现象值得更详细的调查。我们的新数据分析方法估计延伸粘度也值得一些其他实验验证。这些主题将成为2023财年研究的重点。