Torsion balance for measurement of capillary immersion forces
Torsion balance for measurement of capillary immersion forces
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DOI：
10.1021/la950560p
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发表时间：
1996-02-07
期刊：
影响因子：
3.9
通讯作者：
Nagayama, K
中科院分区：
文献类型：
--
作者：
Dushkin, CD;Kralchevsky, PA;Nagayama, K
颗粒-颗粒和颗粒-壁毛细管相互作用被测量为分离距离的函数。“颗粒”是垂直的薄玻璃圆柱体和/或小玻璃球，从空气/液体界面突出。由于在每个颗粒周围形成的重叠的颗粒，颗粒相互吸引。相互作用力由灵敏的扭转微量天平检测。它的原理是用一根细铂丝的扭转力矩来平衡作用在两对粒子之间的一对力的力矩。通过改变线直径，我们获得了几个数量级的力，从颗粒之间小间距的约5达因下降到大间距的0.001达因。用直径约300 μ m的两个圆柱体测量最小力。对于两个球体（直径1.2 mm），我们得到了对应于从液体表面突出的不同高度的力的差异。对于相互作用的球体和玻璃柱，力遵循与两个球体或两个柱之间的力类似的趋势。然而，在球体和玻璃壁的情况下，力首先随着距离的减小而增大，然后在靠近壁处减小，通过最大值。毛细浸没力理论的预测与实验结果定量一致。
Particle-particle and particle-wall capillary interactions were measured as a function of the separation distance. The ''particles'' were vertical thin glass cylinders and/or small glass spheres, protruding from an air/liquid interface. The particles attract each other due to the overlapping of the menisci formed around each of them. The force of interaction is detected by a sensitive torsion microbalance. It is based on counterbalancing the moment of a couple of forces, acting between two pairs of particles, by the torsion moment of a thin platinum wire. By varying the wire diameter, we accessed forces differing by several orders of magnitude, from about 5 dyn at small separation between the particles down to 0.001 dyn at large separation. The smallest force was measured with two cylinders of diameters about 300 mu m. For two spheres (diameters 1.2 mm) we obtained difference in the forces corresponding to different heights of protrusion from the liquid surface. For interacting sphere and glass cylinder the force follows similar trends as the forces between two spheres or two cylinders. In the case of sphere and glass wall, however, the force first increases with decreasing the distance and then decreases close to the wall passing through a maximum. The predictions of the theory of capillary immersion forces are in quantitative agreement with the experimental results.