论文标题
使用落球粘度测定法量化触变胶体悬架的破坏
Quantifying the destructuring of a thixotropic colloidal suspension using falling ball viscometry
论文作者
论文摘要
研究了隆斗液悬架内落球的沉降动力。 Laponite是一种胶体合成粘土，由于粒子间静电相互作用的自发进化而显示出水性悬浮液中的物理衰老。在我们的实验中，将毫米大小的钢球滴入不同年龄的水溶液悬浮液中（即自样品制备以来经过的时间）。使用高速摄像头捕获落球的运动，并从图像中估算其质心速度。有趣的是，我们观察到较大的直径球在整个实验期间无法达到末端速度。我们提出了一个数学模型，该模型解释了在衰老的时间尺度比球落下时间慢得多的laponite悬浮液中的快速结构变化（预计会被落球引起）。对于一系列的球尺寸和Laponite悬架年龄，我们的模型正确预测了球速度的时间依赖性。此外，适合我们的模型，使我们能够估计由于落球的通过而导致的触变悬浮液的破坏率。
The settling dynamics of falling spheres inside a Laponite suspension is studied. Laponite is a colloidal synthetic clay that shows physical aging in aqueous suspension due to the spontaneous evolution of inter-particle electrostatic interactions. In our experiments, millimeter-sized steel balls are dropped in aqueous Laponite suspensions of different ages (i.e., time elapsed since sample preparation). The motion of the falling balls are captured using a high-speed camera and the velocities of their centroids are estimated from the images. Interestingly, we observe that balls of larger diameters fail to achieve terminal velocity over the entire duration of the experiment. We propose a mathematical model that accounts for rapid structural changes (expected to be induced by the falling ball) in Laponite suspensions whose aging time scales are much slower than the time of fall of the ball. For a range of ball sizes and Laponite suspension ages, our model correctly predicts the time-dependence of the ball velocity. Furthermore, fits to our model allow us to estimate the rates of destructuring of the thixotropic suspensions due to the passage of the falling ball.
