Enthalpy-entropy compensation in water sorption by various wood species

Enthalpy and entropy of water sorbed by the sapwood and heartwood of five l ocal softwoods were studied: western hemlock (Tsuga heterophylla), Douglas fir (Pseudotsuga menziesii), western red cedar (Thuja plicata), sitka spruc e (Picea sitchensis), and lodgepole pine (Pinus contorta). Enthalpy and ent ropy show a strong negative relation to the moisture content, the absolute desorption values always being higher than the adsorption ones, but with no clear trend between and within the species. :Furthermore, it is shown that the linear plot of compensation between enthalpy and entropy correlates we ll for water sorption in wood; that water adsorption or desorption are irre versible, and that both are enthalpy-driven mechanisms.