REMARKS ON THE INTERPRETATION OF DATA FROM THE DYNAMIC DROP VOLUME METHOD

The maximum bubble pressure, drop volume, and ring methods were used t o measure the dynamic surface tension for aqueous solutions of dodecyl dimethylphosphine oxide in a wide concentration range. It was shown th at for some concentrations the experimental data obtained from the dro p volume method do not agree with the results from the maximum bubble pressure method. The drop volume data differ also from values predicte d by theoretical models which account for surface expansion and convec tion transfer only. To achieve agreement between data from the drop vo lume method and theoretical results, the actual drop surface area and the state of this surface at the initial time moment have to be includ ed into the boundary conditions of the theory. Conditions are defined at which a discrepancy can be expected between different experimental techniques.