Fungal Decay Resistance and Dimensional Stability of Loblolly Pine Reacted with 1,6-Diisocyanatohexane

George C. Chen


Wood reacted with 1,6-diisocyanatohexane resisted fungal attack and had improved dimensional stability. At 25.8% chemical weight gain, the reacted wood had no weight loss by the brown-rot fungus Gloeophyllum trabeum; at 20.9% and 23.8% chemical weight gains, the reacted wood had antishrink efficiencies (ASEs) of 58% and 61%, respectively, with a small loss of 3% ASE after four cycles of water swelling and drying treatment. At 26.1% chemical weight gain, the reacted wood lost 5.8% bonded diisocyanate in a 12-week soil-block decay test. Evidence of cross-linking between wood and 1,6-diisocyanatohexane was provided by the characteristic carbamate infrared absorption. In the absence of water, 1,6-diisocyanatohexane reacted with wood to form cross-linking wood as the only product; in the presence of water, diisocyanate reacted preferentially with water to form mainly ureas with a small amount of biurets. These chemicals were deposited in the cell lumen of wood. Water vapor sorption of wood reacted with 1,6-diisocyanatohexane indicated that the decay resistance of this modified wood is probably due to the inability of the modified cell wall of wood to absorb sufficient water to support decay.


Cross-linked wood;1,6-diisocyanatohexane;fungal resistance;dimensional stability;loblolly pine;Gloeophyllum trabeum;Pinus taeda

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