Surface Dilational Rheology

The dilational rheology for solutions of surface active compounds and their mixtures can be measured with various methods of different frequency ranges. The most frequently used techniques are based on oscillating drops and bubbles. Besides these techniques, also capillary wave damping is a siutable method, in particular at higher frequencies. The analysis of the resulting data is mainly based on a diffusion model derived by Lucassen and van den Tempel many years ago. For mixtures of surfactants or proteins with surfactants only recently a functioning theoretical apparatus was represented and applied to different mixed adsorption layers. The present chapter summarizes the experimental tools and corresponding theories, and provides well selected examples of classical surfactants and mixtures of milk proteins mixed with a number of surfactants.