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 f requencies that are typically observed during nucleate boiling of water. To understand the additive adsorption/desorption kinetics during boiling, dyn amic surface tension sigma measurements at 80 degreesC are also obtained. T he results indicate significant differences between the dynamic and equilib rium sigma values, as well as between those measured at room and elevated t emperatures. Adsorption isotherms with surface tension and concentration no rmalized by the respective values at critical micelle concentration are sho wn to represent the generalized behavior of surfactants. In the case of aqu eous polymer solutions, the surface-active nonionic polymer HEC is seen to exhibit surfactant-like behavior. For the high viscosity Carbopol 934 solut ions, 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 soluti ons; for HEC solutions, because of their less viscous nature, this correcti on shows no significant change. (C) 2001 Published by Elsevier Science Inc.