The flow of dilute aqueous solutions of macromolecules in various geometries: VII. Mechanisms of resistance in porous media

For pt.VI see ibid., vol.12, p.369 (1979). Three mechanisms have been suggested to account for the high resistance to the flow of dilute solutions of macromolecules in porous media, namely: viscoelasticity of the bulk solution, adsorption of macromolecules on the walls of the micropores thus reducing the mean radius of the pores, and entrapment of macromolecules which then block the pores. James and McLaren's (1975) observations of the flow of dilute polyox solutions through beds of glass beads are discussed in relation to such mechanisms. It is concluded that adsorption will account for the observed effects whereas the other mechanisms, whilst possibly occurring, introduce several difficulties of interpretation.