| 초록 |
Stability of colloidal suspension depends on the balance between hydrodynamic force and colloidal force. When it comes to dispersing nanoparticles, extensional flow is known to be more effective compared to shear flow. However, there’s few study on the dynamics of particle aggregates under the pure extensional flow field. In order to build up the extensional flow, the concept of capillary thinning was utilized. The process of capillary thinning was recorded with a high-speed camera, which allowed us to track the movement of particles at the interval of 62.5 μs. Aggregates broke up by fragmentation, not by erosion which occurs under the shear flow. Particle aggregates were fragmented into one or two big segments which accounted for 40~80% of the initial size, and large number of small remnants which was less than 10% of the initial size. The size distribution of ruptured fragments was correlated with the exponential distribution. |
