2.3.4. Dilational Rheology

A Nima 702 Langmuir balance from Nima Technology equipped with a surface force tensiometer was used to measure the response of the surface tension against sinusoidal changes in the surface area. Thus, it is possible to obtain information about the dilational viscoelatic moduli of the water–vapor interface ε\* = ε + *i*ε", with ε and ε" being the dilational elastic and viscous moduli, respectively, in the frequency range of 10<sup>−</sup>1–10−<sup>2</sup> Hz and at an area deformation amplitude Δ*u* = 0.1, which was verified to be an appropriate value to ensure results within the linear regime of the layer response [52].
