Impregnation and polymerization of vinylic monomers in porous media. I. Kinetics of impregnation

Abstract

In this work, we have studied the mechanism and kinetics of penetration of monomers and of liquids of low molecular weight into porous media such as asbestos cements. Although the phenomenon is physically different from a molecular diffusion, the kinetics of impregnation are well represented by Fick's laws of diffusion. We observe an excellent agreement between the experiment and the theoretical equation as long as the degree of impregnation does not exceed 80%. If, in order to represent this, we use a simplified model introducing a flow governed by Poiseuille's law through a bundle of capillaries of the same diameter, we obtain a parabolic law which is verified up to only 55%. We have demonstrated the physicochemical parameters which influence the kinetics of impregnation. The results can be summarized by the following empirical equation: Where η represents the viscosity of the liquid, γ the surface tension, θ the angle of contact, γ the average radius, and ϵ the porosity; D* appears as a constant equal to 2.0 × 109 cm−2. The standard deviation of its determination is 0.14 × 109 cm−2.