Phase transformations of wood cell wall water

Abstract

The amount of apparently nonfreezing water per dry mass unit significantly differs between earlywood and latewood, and drying changes the nonfreezing water content of earlywood cell walls in a time-dependent manner. However, the equilibrium moisture content of spruce wood is not affected by drying and rewetting. The results indicate that different mechanisms govern these two types of phase transformations of cell wall water. The nonfreezing water content, as determined using differential scanning calorimetry, appears to be a nonequilibrium property. It is hypothesized that the measured changes in nonfreezing water content mostly reflect changes in the porous cell wall structure, on a scale well above the molecular scale, rather than the abundance of chemical adsorption sites.