Role of surfactant structure on surface and foaming properties

The influence of surfactant structure on interface properties was estimated from measurements of the static and dynamic surface tension and the interf ace complex modulus, as obtained from an image analysis technique based on the oscillating bubble method. A simplified kinetic model of surfactants mo lecular adsorption at the gas-liquid interface was introduced and the rate of adsorption was determined from measurements of the dynamic surface tensi on. The mean life time of foams generated from bubbling air through differe nt surfactant solutions was measured using a modified Bikerman device. The major conclusion arising from this study, as expected from basic considerat ions, was that the chain length of the hydrophobic part of the surfactant p lays a determining role with respect to both the kinetic migration to the i nterfaces and the ensuing surface activity, as shown by the extent of phase delay and foam stability. (C) 2001 Elsevier Science B.V. All rights reserv ed.