ISO 9101:1987 Preview
Surface active agents -- Determination of interfacial tension -- Drop volume method
This standard was last reviewed and confirmed in 2013. Therefore this version remains current.
The volume of a drop of an aqueous phase formed at the end of a vertical capillary tube is measured when it detaches from the tube in contact with the organic phase. The interfacial tension between two liquid phases is obtained by balancing the weight of the drop with the interfacial tension force supporting it and applying a correction factor. Then the interfacial tension is calculated from the volume of the falling drop, the outer capillary radius, the density difference between the two liquid phases and the acceleration due to gravity.
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