Figure 16.

(a) Response of a surfactant monolayer to a dilatational deformation that is fast or slow relative to rate of replenishment by adsorption from the bulk. The monolayer is effectively insoluble as ζ_d → 0, and the elastic modulus is highest (= E⁰) in this limit. Conversely, perturbations of surface concentration from equilibrium are rapidly eliminated by adsorption and the surface elasticity is weak when ζ_d ≫ 1. (b) The dynamic Gibbs modulus E and apparent dilatational surface viscosity ${\kappa }_s^{\text{ads}}$ from (4.34).