Dynamic Surface Tension and Foaming Properties of Aqueous Polyoxyethylene n-Dodecyl Ether Solutions

Abstract

The contribution of dynamic surface tension (γ t), obtained using the maximum bubble pressure method, on foamability and foam stability is presented for aqueous solutions of a series of polyoxyethylene dodecyl ethers; C 12H 25O(C 2H 4O) n H, where n = 5-53. In the shorter measuring time region (<1 s), the maximum rate of the decrease in the surface tension, ( dγ t/ dt) max obtained from the γ t, increases with an increase in ethylene oxide (EO) units. The initial foamability, measured by the Ross-Miles technique, was correlated with the increase in the values of ( dγ t/ dt) max. However, in the longer measuring time region (>1 s), at which the dynamic surface tension approaches the meso-equilibrium (γ m) t γ m decreased with a decrease in EO units. The degree of elongation of lamellae ( L lamellae), measured by a laminometer, decreased with an increase in EO units. The residual foam stability, measured by the Ross-Miles techniques, was also correlated with the decrease in the values of L lamellae. According to these techniques, the significance of the surface tension gradient for foamability is elucidated.