Characterization of the Dynamic Surface Tension of Aqueous Film-Forming Foam

摘要

We have characterized the dynamic surface tension of several commercial varieties of aqueous film-forming foam (AFFF) using a maximum bubble pressure tensiometer. Dynamic surface tension governs the behavior of surfactant-containing solutions on short time scales before thermo-dynamic equilibrium can be achieved; this typically includes many aspects of AFFF use including foam formation. The approach to equilibrium surface tension is compared for the different products. Additionally, the effects of varying the dilution of the AFFF concentrate by water, variation of the salinity of the water and variations in ambient temperature on the dynamic surface tension are investigated. Noteworthy in the findings is that a sufficient lowering of surface tension of AFFF to form an aqueous film on typical hydrocarbon fuels does not occur for several seconds.