Extensional rheology of dilute polymer solutions in oscillatory cross-slot flow: the transient behaviour of birefringent strands
Extensional rheology of dilute polymer solutions in oscillatory cross-slot flow: the transient behaviour of birefringent strands
复制标题
DOI：
10.1007/s00397-009-0420-6
复制
发表时间：
2010-06-01
期刊：
影响因子：
2.3
通讯作者：
Yuan, Xue-Feng
中科院分区：
文献类型：
--
作者：
Haward, Simon J.;Odell, Jeffrey A.;Yuan, Xue-Feng
双折射链是理解聚合物非牛顿流动的关键，特别是在拉伸方面。利用微流控拉伸流振荡流变仪加上微测速仪（μ-PIV），我们报告实验的起源，稳态和衰减等股，连同流变学的后果。对于紧密单分散无规聚苯乙烯，我们报告了即使在低浓度下聚合物对流动的巨大影响。经常观察到的启动“过冲”的应力和双折射观察到前所未有的稀释和讨论的局部应变率。链衰减显示出明显的滞后现象。这些因素是最重要的真实的流动，如循环和毛细管入口流建模。即使使用的样品具有紧密的单分散性和良好的特性，残留的多分散性在流动行为中也起着至关重要的作用。
Birefringent strands are key to understanding polymeric non-Newtonian flows, especially in extension. Utilising microfluidic extensional flow oscillatory rheometry coupled with microvelocimetry (mu-PIV), we report experiments on the genesis, steady state and decay of such strands, together with rheological consequences. For closely monodisperse atactic polystyrene, we report massive effects of the polymer on flow even at low concentrations. The often observed startup "overshoot" in stress and birefringence is observed at unprecedented dilution and discussed in terms of the local strain rate. Strand decay shows pronounced hysteresis. These factors are most important in modelling real flows such as cyclic and capillary entrance flows. Even with the closely monodisperse and well-characterised samples used, residual polydispersity plays a vital role in flow behaviour.