Dynamic and equilibrium surface tension of aqueous surfactant and polymeric solutions

Dynamic and equilibrium surface tension data for aqueous solutions of four surfactants and two polymers are experimentally obtained using the maximum bubble pressure method. The additives employed are SDS, SLES, Triton X-100, Triton X-305, HEC QP-300, and Carbopol 934. Measurements are obtained at a surface age of 50 ms, which represents the dynamic conditions for bubble frequencies that are typically observed during nucleate boiling of water. To understand the additive adsorption/desorption kinetics during boiling, dynamic surface tension sigma measurements at 80 degreesC are also obtained. The results indicate significant differences between the dynamic and equilibrium sigma values, as well as between those measured at room and elevated temperatures. Adsorption isotherms with surface tension and concentration normalized by the respective values at critical micelle concentration are shown to represent the generalized behavior of surfactants. In the case of aqueous polymer solutions, the surface-active nonionic polymer HEC is seen to exhibit surfactant-like behavior. For the high viscosity Carbopol 934 solutions, however, measured dynamic sigma values are found to be significantly higher than the actual values due to the viscous resistance offered by the test fluid against the growing bubble. A correction procedure is specified, and corrected values of dynamic sigma are obtained for Carbopol 934 solutions; for HEC solutions, because of their less viscous nature, this correction shows no significant change. (C) 2001 Published by Elsevier Science Inc.