Surface rheological properties of foaming agent C12E8
- 化学化工－已发表论文 
The gravity drainage of foam leads to the deformation of liquid film that results in the surface tension gradients and the heterogeneity of film thicknesses. The deformation of liquid films causes the rupture of films. However, the deformation of liquid films produced from surface active agents solution can be spontaneously restored by the "Marangoni effect". This ability of restoration is connected with the surface rheology. The aim of this paper is to investigate the surface rheology of foaming agent C12E8 by the damped longitudinal waves method and explains the restoration mechanism of surface tension gradient due to the stretched surface. It is shown that the surface of foaming agent C12E8 is viscoelastic and that the surface dilational modulus depends on the frequency of the perturbation. The increase of dilational modulus with concentrations at lower concentration is caused by the surface adsorption of molecules C12E8, while the decrease at higher concentration is caused by bulk to surface diffusion exchange.