Physical and mechanical properties of wood after moisture conditioning

Some properties of wood (hinoki: Chamaecyparis obtusa) moisture-conditioned by an adsorption process from a dry state and by two desorption processes (from a water-saturated state and from a state with a moisture content slig htly below the fiber saturation point) were investigated. The moisture cont ents of wood conditioned by the adsorption process and by the desorption pr ocess continued to approach to one another for the moisture-conditioning pe riod of over 50 weeks. Accordingly, sorption hysteresis should be regarded as a transitional phenomenon that occurs during the process of approaching the true equilibrium, which requires a long time. The wood conditioned by t he desorption process beginning from a water-saturated state showed slightl y smaller dimensions than those conditioned by the adsorption process with the same moisture content: however, the wood conditioned by the desorption process from a moisture content below the fiber saturation point showed sli ghtly larger dimensions than those conditioned by the adsorption process. T he wood conditioned by the adsorption process from a dry state showed a hig her modulus of elasticity and modulus of rupture than did the wood conditio ned from a water-saturated state with the same moisture content. The mechan ical properties of the wood also varied based on the states at which the de sorption process was started. This is a notable characteristic of the relat ion between the drying condition and the mechanical properties of wood.