Drying Mechanics of Gels

Abstract

ABSTRACTA model is presented for the stresses and strains that develop in a gel during drying. The driving force for shrinkage is assumed to be the interfacial energy, and the gel is considered to be viscoelastic. The liquid seeks to flow into the dry region of a gel in order to replace the solid-vapor interface with a solid-liquid interface having lower specific energy. This creates a “redistribution pressure” that causes the wet region to contract. The free contraction rate can be calculated by equating the decrease in surface energy with the energy dissipated in viscous flow as the gel contracts. The permeability of the gel to the liquid in the pores is especially important in the early stages of drying, and may control the contraction rate. The model allows quantitative predictions of contraction rate and stress during drying. In this paper, the model is applied to a plate drying from both sides.