Dynamic capillary pressure measurements in the short time range by applying a fast growing drop technique

Abstract

The capillary pressure technique is the method of choice for any tensiometry measurements in microgravity, as all bubbles and drops have a spherical shape. A combination of fast drop formation based on a known constant liquid flow and fast data acquisition of measured capillary pressure gives access to dynamic interfacial tensions in the range of milliseconds. Also the maximum drop pressure method, an equivalent to the maximum bubble pressure technique as fastest dynamic surface tension method, can be practised by the same set-up. The technique was developed already 15 years ago [ii] and now further refined during the MAP FASES* supported by the European Space Agency [ii]. Besides a detailed description of the technical parameters, experimental results for emulsion relevant systems are presented. The set-up presented here is based on a commercial drop and bubble profile analysis tensiometer which appears to be a kind of in-situ technique for membrane emulsification processes. The instrumental set-up is suitable also for oscillating drop and bubble experiments up to frequencies of several hundreds Hz.