Water States in Yellow Poplar During Drying Studied by Time-Domain Nuclear Magnetic Resonance

Minghui Zhang, Ximing Wang, Rado Gazo


The time-domain nuclear magnetic resonance (NMR) technique can easily distinguish water states according to spin-spin relaxation time and can give more quantitative information on water in wood than any other method. In this study, water states in yellow poplar were investigated with a time-domain NMR technique. Water migration during drying was also analyzed. The results of this study show that yellow poplar has five components in water states (bound and free water) according to spin-spin relaxation time at moisture contents greater than 100%. The number of different water states decreased with decreasing moisture content. The longest spin-spin relaxation time was about 400 ms for free water, and the shortest was about 1 ms for bound water. With the NMR resonance technique, water states in yellow poplar drying are distinguished easily and migration from one water state to another can be analyzed quantitatively. This technique can benefit wood drying modeling and simulation.


Water state;migration;NMR;relaxation time

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