NMR detection of liquid-like wood polymer component in dry aspen wood

A liquid-like phase, which cannot be assigned to water, has been observed in dry aspen wood using proton Nuclear Magnetic Resonance (NMR). This phase appears at approximately 45 °C as the temperature of the wood sample is increased from room temperature. As the free induction decay signal of the protons associated with this phase has a spin-spin relaxation time similar to that of water, bound to the wood polymer components at low hydration, this observation has relevance in wood moisture content determination using NMR and in the assignment of NMR signal components to wood/water components. It is proposed that a glass transition within a part of the wood extractives is responsible for the occurrence of this phase at the higher temperatures.

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