Stability of Acetylated Wood To Environmental Changes

Roger M. Rowell, Rebecca S. Lichtenberg, Pia Larsson

Abstract


Acetylated wood is more dimensionally stable and resistant to biological attack than unacetylated wood. In this study, the stability of acetylated wood was tested under various pH, temperature, and moisture conditions. Ground acetylated southern yellow pine and aspen flakes were treated with buffer ranging from 2 to 8 pH, exposed at 24 C, 50 C, or 75 C for different periods, and tested for acetyl content. At 24 C, acetylated wood was more stable at pH 6 than pH 2, 4, or 8. At 50 C and 75 C, acetylated wood was more stable at pH 4 than at the other pH values. The half-life of acetylated wood continuously in contact with a buffered liquid at pH 6 and 24 C was approximately 30 years. For acetylated wood used under normal circumstances, the half-life would be expected to be much longer. Acetylated southern yellow pine and aspen flakes were also (1) kept at 90% relative humidity at 27 C for 6 years or (2) cycled (42-day cycle) between 90 and 30% relative humidity for 5 years. The loss of acetyl was less than 2% in both the constant and cyclic relative humidity tests. The stability of acetylated wood suggests that such wood can be used for products exposed to changes in humidity.

Keywords


Acetylation;stabilization;pH;moisture

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