Herzhaft Benjamin
Institut Français du Pétrole, 1 & 4 Avenue de Bois-Préau, Rueil-Malmaison, 92852, France.
J Colloid Interface Sci. 2002 Mar 15;247(2):412-23. doi: 10.1006/jcis.2001.8153.
This experimental work deals with rheological properties of aqueous foams and slip phenomena. Rheological measurements are performed on a stable foam with a parallel plate rheometer. When a constant shear rate is applied to foam, two regimes can be identified in the recorded stress vs time curve: a transient regime where the structure evolves and where the recorded stress varies, followed by a steady state regime where the stress is stabilized. Measurements, modeling, and elimination of the slip velocity are performed. Experiments with grooved surfaces allow elimination of slip at the wall. From measurements at two gaps with smooth surfaces, we use two slip correction methods and check their validity by a direct comparison with actual measurements (with grooved surfaces). A foam rheological equation can be determined from the measurements. Finally, using an optical device coupled with image analysis software, foam texture is investigated on the basis of its evolution with shear rate and time. Evolution of the bubbles size and arrangement into the gap with time of shearing are shown. The transient regime is identified as a regime where the intimate structure of the foam evolves. Slip velocity is also evidenced and measured with the visualization device.
这项实验工作涉及水性泡沫的流变特性和滑移现象。使用平行板流变仪对稳定泡沫进行流变测量。当对泡沫施加恒定剪切速率时，在记录的应力与时间曲线中可识别出两种状态：一种是瞬态状态，在此期间结构发生演变且记录的应力发生变化，随后是稳态状态，此时应力稳定下来。进行了滑移速度的测量、建模和消除。带有凹槽表面的实验可消除壁面处的滑移。通过在两个光滑表面间隙处的测量，我们使用两种滑移校正方法，并通过与实际测量值（带有凹槽表面）直接比较来检验其有效性。可根据测量确定泡沫流变方程。最后，使用与图像分析软件相结合的光学装置，基于泡沫纹理随剪切速率和时间的演变对其进行研究。展示了剪切过程中气泡尺寸和间隙内排列随时间的演变。瞬态状态被确定为泡沫紧密结构发生演变的状态。还通过可视化装置证实并测量了滑移速度。
