A NMR study of water distribution in hardwoods at several equilibrium moisture contents |
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Authors: | Giana Almeida Stéphane Gagné Roger E Hernández |
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Institution: | (1) Centre de recherche sur le bois (CRB), Département des sciences du bois et de la forêt, Université Laval, G1K 7P4 Québec, QC, Canada;(2) Département de biochimie et de microbiologie, Université Laval, G1K 7P4 Québec, QC, Canada |
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Abstract: | The water state of one tropical (Robinia coccinea) and two temperate (Acer saccharum and Fagus grandifolia) hardwoods was determined at different equilibrium moisture contents (EMC) during desorption at 25°C. NMR technique was used
to separate different components of water in wood. The species studied presented different structures, which were apparent
on the spin–spin relaxation T2 values. Three different water components were separated: slow T2 (liquid water in vessel elements), medium T2 (liquid water in fiber and parenchyma elements) and fast T2 (bound or cell wall water). The NMR results showed that even at equilibrated conditions a region exists where loss of liquid
water and bound water takes place simultaneously. This region will vary according to the wood structure. Finally, liquid water
was present at EMC lower than the fiber saturation point, which contradicts the concept of this point when considered as a
bulk property of wood. |
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