Microfluidics approach to investigate foam hysteretic behaviour
Microfluidics approach to investigate foam hysteretic behaviour
复制标题
研究泡沫滞后行为的微流体方法
DOI：
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发表时间：
2019
影响因子：
2.8
通讯作者：
D. Vigolo
中科院分区：
文献类型：
--
作者：
L. Labarre;D. Vigolo
泡沫稳定性通常指的是在静态条件下随时间演化的泡沫。然而，在日常生活中，泡沫会经历无数次变形。泡沫稳定性的一个特征是泡沫抵抗变形并在变形后恢复其初始性质的能力。在此开发的技术允许定性地评估在聚焦流动的微流控装置中变形后的泡沫回收性能。通过引入类似于标准三步试验的方法来评价泡沫的滞回性能，在三个变形阶段中通常研究粘度的恢复。通过改变恒定液体压力的气体压力，很好地控制了壁面上升和下降变形的诱导循环，分析了泡沫行为。因此，在竹模对应的高变形阶段并定性地测量滞后程度后，以双排泡沫模样为参照，研究了其恢复情况。所研究的样品包括一系列牛顿水溶液，其中含有5CMC(临界胶束浓度)的十二烷基硫酸钠(SDS)。由于粘度的增加，出现了滞后效应，导致了滞后。较高的表面弹性会产生较小但不可忽略的滞后，这是因为气泡重排持续时间的增加导致了弹性能量的过剩。目前的研究在一定程度上加深了我们对微通道中触发或增强泡沫滞后的机理的理解。这些发现将对许多工业过程感兴趣，在这些过程中，泡沫被提交到从食品工业应用到生物系统的工艺线上的一系列变形步骤。一种三步测试的示意图，包括通过改变恒定液体压力的气体压力而获得的上升和下降压力斜率。
Foam stability often refers to the foam left to evolve with time in static conditions. However, in everyday life, foams are submitted to numerous deformations. A feature of foam stability is represented by the foam’s ability to resist to the deformation and to recover its initial properties after deformation. The technique developed here allows for a qualitative evaluation of the property of foam recovery after a deformation in a flow-focusing microfluidic device. The foam hysteretic behaviour was evaluated by introducing the analogous of a standard three-step test in which the recovery of viscosity is commonly studied over three deformation stages. The foam behaviour is analysed over an induced cycle of ascendant and descendant deformation at the wall, well controlled by varying the gas pressure for a constant liquid pressure. Thus, the recovery of the two-row foam pattern used as reference is studied after a high deformation phase corresponding to the bamboo pattern and the level of hysteresis is measured qualitatively. The samples investigated comprise a range of Newtonian aqueous solutions containing 5 cmc (critical micellar concentration) of sodium dodecyl sulphate (SDS). A retardation effect was observed leading to hysteresis caused by the increase in viscosity. A higher surface elasticity produced a smaller but non-negligible hysteresis due to an excess in elastic energy caused by the increase of the duration of the bubble rearrangements. The present study has gone some way towards enhancing our understanding of the mechanisms triggering or enhancing foam hysteresis in a microchannel. The findings will be of interest to many industrial processes where foams are submitted to a series of deformation steps along the process line from food industrial applications to biological systems. A schematic of the three-step test consisting in an ascending and descending pressure ramps obtained by varying the gas pressure for a constant liquid pressure.
影响因子：
6.1
作者：
Bauer, Wolfgang-Andreas C.;Fischlechner, Martin;Huck, Wilhelm T. S.
通讯作者：
Huck, Wilhelm T. S.