Ehdotuksen tiedot

This document specifies a method for determining the dynamic surface tension of liquids based on the pressure in gas bubbles. The dynamic surface tension of solutions is influenced by surface-active molecules in the solution (often surfactants in water-based solutions). The surface tension is measured at a newly created interface depending on the age of this surface. This allows direct conclusions to be drawn about how quickly and strongly the surfactants in the solution reduce the surface tension of a new surface. The interface used to determine surface tension is renewed with each gas bubble. Due to the principle, very short measurement times in the millisecond range are possible, which makes the test method particularly suitable for surfactant-containing solutions of high concentration (significantly above the critical micelle concentration), e.g. in electroplating baths, cleaning baths, preferably low-viscosity Newtonian paints, inks. The sequence of air bubbles resulting from a gas volume flow enables continuous measurement without the sample having to flow through the measuring system. For the purpose of controlling surfactant concentration, surface tension is monitored at an appropriate, well-defined surface age.