小角躺滴法测定低界面张力

SMALL ANGLE SESSILE DROP METHOD FOR LOW INTERFACIAL TENSION MEASUREMENT

在测定界面张力,特别是测定低界面张力的各种方法中,躺滴法占有相当重要的位置。但一般的躺滴法都要求获得赤道半径(图1中的x_e)数据.故躺滴与基底之间的接触角必须大于90°.这在低界面张力体系中常常难以实现,致使躺滴法的应用受到限制。本文提出一种新的躺滴法,它不依赖于接触角的大小,只需测定躺滴轮廓线上两个相关点的坐标,根据所给数值表即可计算出界面张力,从而为躺滴法应用于低界面张力。

Interfacial tension is important in various industry processes, particularly in petroleum recovery where low or ultralow interfacial tension between oil and water bring about great benefit. For the measurement of interfacial tension, serveral kinds ofmethod can be used. Those depending on size and shape of liquid drop including se-ssile drop, pendant drop and sprinning drop methods are suitable. Among them, se-ssile drop method has the advantage of simple equipment and procedure. Usually, theradius of drop equator is necessary for sessile drop method. Hence a drop with con-tact angle larger than 90°is needed. However, this is not always the case in prac-tice. In systems of low or ultralow interfacial tension, it is seldom to form a contactangle larger than 90°. This had been a restriction for the application of sessile dropmethod. In this work, procedures for obtaining interfacial tension from size andshape with small contact angle (<90°) was provided. Good precision of this methodwas shown by apying to typical system (butanol/water). Comparasons of it with other methods have been made.