Spreading of liquids on gel surfaces

In this work we present a simple model for the kinetics of spreading of film-forming liquids on polymer gels. The model is compared with experiments and fair agreement is obtained. The spreading process can be theorized by considering the gel as a thick liquid layer containing a fibrous material (i.e., the polymer network). The spreading theory of Joos and Pintens is extended in such a way that the penetration of the flow into the bulk of the gel-which plays the major role in the kinetics of the spreading-is described by the Debye-Brinkman equation. It is also shown that spreading experiments can provide information on the surface structure of the underlying gel. (C) 2000 American Institute of Physics. [S0021-9606(00)70540-X].