Penetration of a non-swelling liquid into a tableted porous medium

The imbibition of a liquid into porous substrates is a phenomenon of interest in a wide array of processes both in nature and industrial applications. Among the latter are several of relevance in the fast moving consumer goods industry, such as the application of coating surfactants to the formulation of powder detergents. The structure of the substrate and the properties of the liquid as well as the type of interaction will determine the kinetics of imbibition. This work presents a methodology to compact powders of relevant composition in the formulation of detergents into tablet preparations. Non-invasive techniques are used to characterise the tablet surface (White-light interferometry) and internal structure (micro-computed tomography) of the substrate. Imbibition of n-hexadecane, which does not swell the substrate, has been studied. The initial contact angle has been studied as a function of roughness, showing that this variable did not affect greatly this variable. Finally, the penetration kinetics of droplets of the liquid showed a strong dependence with respect to the porosity of the substrate.