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.

2022 财年，完成了测量平面拉伸流动装置中粘弹性聚丙烯酰胺溶液（0.005 至 0.04 wt% 稀浓度）压降和速度场的实验。 2021 财年期间开发的新型单轴和双轴拉伸流动装置也完成了压降和速度场测量。已经开发出一种新的数据分析来估计牛顿和粘弹性流体的拉伸粘度。这确保了牛顿流体以及小流速下的聚合物溶液获得预期的（恒定）拉伸粘度。在高流速下，聚合物溶液的拉伸粘度增加至取决于拉伸模式的稳定值。对于测试的稀溶液，单轴和平面延伸的平台值彼此相等，并且是双轴延伸的平台值的两倍。这与有限可扩展非线性弹性哑铃模型一致，该模型通常用于在理论上描述此类流体。根据 2021 财年和 2022 财年迄今为止所做的工作，已经准备了两篇期刊论文，目前这两篇论文都在《流变学杂志》上进行审查。此外，粘弹性聚合物溶液的实验揭示了高流速下一些有趣的不稳定现象，这些现象值得研究。的更详细的调查。我们用于估计拉伸粘度的新数据分析方法也值得一些额外的实验验证。这些主题将成为2023财年的研究重点。