The rheology of polymer solution elastic strands in extensional flow
The rheology of polymer solution elastic strands in extensional flow
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DOI：
10.1007/s00397-010-0453-x
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发表时间：
2010-05
期刊：
影响因子：
2.3
通讯作者：
S. Haward;J. Odell;Zhuo Li;X. Yuan
中科院分区：
文献类型：
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作者：
S. Haward;J. Odell;Zhuo Li;X. Yuan
我们应用微振荡交叉槽拉伸流的半稀释聚（环氧乙烷）的解决方案。采用微粒子图像测速技术（μPIV）对真实的局部流场进行了探测。极端的流动扰动观察，双折射股延伸聚合物起源于停滞点。这与拉伸粘度的大幅增加相一致。结合驻点流和μPIV技术，我们可以直接研究股线中的应力和应变率，从而确定局部股线的真实拉伸粘度。发现链中的特劳顿比为~4000，在有报道的特劳顿比的最高值中。考虑到围绕高弹性股线的出口通道中的流动，提出了跨装置的压降和表观拉伸粘度的最大极限。这对理解在其他驻点流动情况下报道的高Deborah数伸展变薄有影响。
We apply micro-oscillatory cross-slot extensional flow to a semi-dilute poly(ethylene oxide) solution. Micro-particle image velocimetry (μPIV) is used to probe the real local flow field. Extreme flow perturbation is observed, where birefringent strands of extended polymer originate from the stagnation point. This coincides with a large increase in the extensional viscosity. The combination of stagnation point flow and μPIV enables us to investigate directly the stress and strain rates in the strand and so determine the true extensional viscosity of the localised strand alone. The Trouton ratio in the strand is found to be ~4000, amongst the highest values of Trouton ratio ever reported. Consideration of the flow in the exit channels surrounding the highly elastic strand suggests a maximum limit for the pressure drop across the device and the apparent extensional viscosity. This has implications for the understanding of high Deborah number extensional thinning reported in other stagnation point flow situations.