结合图像数字化技术用悬滴法测动态界面张力——动态界面张力与表面活性剂浓度的关系

引　言从微观机理上讲 ,能否制得稳定乳状液与乳化剂扩散速度、界面层吸附速度和成膜分子间协同作用等因素有关 ,而这些信息可以通过测动态界面张力反映出来 ,因此测动态界面张力是研究乳状液稳定性微观机理的一条重要途径 .测动态界面张力的方法1] 很多 ,其中悬滴法 (滴外形法的一种 )有独特的优点1] .目前 ,在国外已利用该法展开了许多卓有成效的研究工作2～ 6 ] ;国内李佟茗7] 等已报道采用计算机图像采集技术实时记录气泡长大过程测动态表面张力的工作 ;田宜灵8] 等则报道了用数字化摄像仪拍摄悬滴 ,以选面法9] 计算静态界面张力…

DETERMINATION OF DYNAMIC INTERFACIAL TENSION BY COMPUTER-AIDED PENDANT DROP DIGITIZATION——EFFECT OF SURFACTANT CONCENTRATION ON DIT

A pendant drop tensiometry apparatus aided by video-image digitization technology was established, by which static interface or surface tension of some liquids was measured with satisfactory results.In order to study the effect of emulsifier concentration on emulsion stability, dynamic interfacial tension was measured between toluene and water against concentration of Tween 60(Polyoxyethylene(20) stearyl-sorbitanate). As expected, higher concentration is the Tween 60 solution in toluene injected into the toluene phase, faster falls the interface tension between toluene and water.Furthermore, it reveals interestingly that two steps of diffusion occur in the system, i.e ., at low and high concentration, after the surfactant solution is injected.The characteristic process of dynamic interface tension can be ascribed to diffusion control because of linearity between interface tension and the minus second root of aging time.The discovery is correlated to the fact that much higher concentration of surfactant above its critical micelle concentration is often required when a stable emulsion is planned to prepare.