ABSOLUTE MOISTURE-CONTENT DETERMINATION OF ASPEN WOOD BELOW THE FIBER SATURATION POINT USING PULSED NMR

Pulsed Nuclear Magnetic Resonance (NMR) was shown to be effective in determining the absolute moisture content (M) below the fiber saturation point of aspen (Populus tremuloides, Michx.) prepared in water vapor adsorption and desorption environments. The only requirements for the M determination of a particular sample are that the proton spin density of the wood relative to that of the water is known and that a free induction decay is acquired and analysed. In samples prepared in liquid water adsorption experiments and for M values near the fiber saturation point in the water vaopr adsorption samples it was found that NMR predicted a higher moisture content than the actual M of the samples. Such differences are discussed in terms of magnetization exchange and structural/dynamical changes in the wood cell wall components. A connection between these proposed effects and water molecule cluster formation is presented.