模拟乳状液中微小液滴间的相互作用力

对商品化的DCAT21表面/界面张力仪进行改造, 用于直接测量液滴间相互作用力, 同时用数码摄像头Digital 3.0观察记录两液滴接近, 挤压, 排液, 聚并等过程. 研究发现, 溶液中微小液滴间的相互作用力随距离的变化曲线能够提供分散液滴的行为特征信息: 曲线上不同阶段的斜率反映力的大小; 从液滴接触后到聚并前的挤压距离反映液滴的稳定性. 表面活性剂种类不同, 对两液滴聚并所起的稳定作用不同, 非离子表面活性剂具有较好的稳定作用. 溶液中聚合物分子在薄液膜中形成具有一定强度的层状结构, 阻碍液滴聚并, 受力曲线呈阶梯状.

Interaction Forces Between Simulated Mini Liquid Droplets of Emulsions†

The interaction forces between liquid droplets were measured directly by reformed commercial DCAT21 tensiometer. The processes of approaching, squeezing and coalescence that occur between two liquid drops were observed and recorded by digital camera Digital 3. 0. The experimental results indicate that the variation curves of interaction forces between mini droplets as a function of distance can provide the information of characteristic behavior of the dispersed droplets. The slopes of different stages of the curves can represent the magnitude of force and the squeezing distance before the coalescence can quantitatively reflect the stability of droplets. Different types of surfactants have different effects on hindering coalescence of two droplets and the nonionic surfactant TX-100 shows the better effect of stabilization. The coalescence of two droplets will be hindered by the layer structure formed by polymer molecules in thin liquid film. As a result, the force curves are step-shape.