Moisture Content-Water Potential Relationship of Sugar Maple and White Spruce Wood From Green to Dry Conditions

Maurice Defo, Yves Fortin, Alain Cloutier

Abstract


The moisture content-water potential relationship was determined at 40°C and 60°C for sugar maple (Acer saccharum Marsh.) sapwood and at 60°C for white spruce (Picea glauca (Moench.) Voss.) heartwood from green to dry conditions. The pressure membrane technique was used for high moisture contents and equilibration over salt solutions for low moisture contents. The results show that at high moisture contents, the equilibrium moisture contents obtained from the green condition are lower than those obtained from full saturation (boundary desorption). It is recommended that the sorption history must be taken into account when modeling wood drying. Water potential at a given moisture content increases with temperature. There is a characteristic plateau in the green moisture content-water potential relationship obtained for sugar maple at water potentials between -2,000 and -6,000 J kg-1, which can be attributed to its heterogeneous capillary structure. The maximum concentration of effective pore radius occurs at 0.02 μm in the case of sugar maple, corresponding to the size of the pit membrane openings.

Keywords


Water potential;sugar maple;white spruce;pore size distribution

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