Passive non-linear microrheology for determining extensional viscosity
Passive non-linear microrheology for determining extensional viscosity
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DOI：
10.1063/1.4993736
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发表时间：
2017-10
影响因子：
4.6
通讯作者：
K. Hsiao;J. Dinić;Yi Ren;Vivek Sharma;Charles M. Schroeder
中科院分区：
文献类型：
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作者：
K. Hsiao;J. Dinić;Yi Ren;Vivek Sharma;Charles M. Schroeder
拉伸粘度是复杂流体的一个重要性质，它对聚合物溶液、熔体和胶体悬浮液的非平衡行为和加工有很大影响。在这项工作中，我们使用微流体技术来确定稳定的拉伸粘度的聚合物溶液，通过直接观察颗粒迁移在平面拉伸流。示踪剂颗粒悬浮在DNA和聚环氧乙烷的半稀释溶液中，并且斯托克斯阱用于限制在交叉槽装置中的聚合物溶液的延伸流中的单个颗粒。观察到颗粒迁移的方向横向流动，由于正常的应力，和颗粒迁移的跟踪和量化使用的压电纳米定位阶段在微流体流动实验。然后使用二阶流体模型分析颗粒迁移轨迹，该模型准确地预测由于法向应力差而产生的迁移。使用这个分析框架，拉伸粘度可以确定从…
Extensional viscosity is a key property of complex fluids that greatly influences the non-equilibrium behavior and processing of polymer solutions, melts, and colloidal suspensions. In this work, we use microfluidics to determine steady extensional viscosity for polymer solutions by directly observing particle migration in planar extensional flow. Tracer particles are suspended in semi-dilute solutions of DNA and polyethylene oxide, and a Stokes trap is used to confine single particles in extensional flows of polymer solutions in a cross-slot device. Particles are observed to migrate in the direction transverse to flow due to normal stresses, and particle migration is tracked and quantified using a piezo-nanopositioning stage during the microfluidic flow experiment. Particle migration trajectories are then analyzed using a second-order fluid model that accurately predicts that migration arises due to normal stress differences. Using this analytical framework, extensional viscosities can be determined from...