Chapter 8 - Density and moisture relations

Abstract

Cork is a light material that floats on water with large buoyancy and that slowly absorbs water. This is the result of its cellular structure formed by hollow and closed cells with a small solid fraction that is concentrated in thin cell walls, without any intercellular communication channels. This chapter describes the physical properties of cork related to density and the factors involved in its variation, and to its behavior with water vapor and liquid water, such as the equilibrium moisture content of the material in different environments, the absorption of liquid water at various temperatures, and the drying process. Such properties are involved in the industrial processing of cork, from the field drying of the cork planks to the boiling of cork in water and subsequent moisture variation along the production line. Several of the other properties of cork, namely mechanical properties, are influenced by the water content of the material. The wettability of cork surfaces by liquids is also discussed.