The permeability (D) of alkoxide-derived silica gel is measured by establishing a pressure gradient in the pore liquid in a thin (∼ 2 mm) sheet of gel. In these experiments, the layers were thin enough to minimize the viscoelastic effects discussed in Part I. For an acid-catalyzed gel (A) with a homogeneous microstructure, the order of magnitude of D is found to be in agreement with the Carman-Kozeny equation. For a base-catalyzed gel (B2) D is larger than predicted, presumably because of relatively large pores in the inhomogeneous network. The permeability drops by ∼ 2 orders of magnitude when the layers are partially dried.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Materials Chemistry