Decay isocyanate modified wood

Loblolly pine modified by 1,6-diisocyanatohexane (HDI) was found to be resistant to attack by G. trabeum at a WPG of 26 % (Chen, 1992c). At 26 % WPG, 6 % of bonded chemical was lost during a 12-week soil decay test. When moist wood was used for reaction, the HDI reacted mainly to form ureas and biurets. It was stated that the decay resistance of HDI modified wood was probably due to the inability of the modified cell wall to absorb sufficient amounts of water to support decay. Although wood reacted with chloro-sulphonyl isocyanate lost only 1.3 % mass when exposed to G. trabeum in a decay test, it was reported that 50 % of the bonded chemical was lost in this test. 

Cardias Williams and Hale (1999, 2003) studied the effect of the carbon chain length of the isocyanate upon decay resistance of the modified wood. Wood was reacted with butyl or hexyl isocyanate, or HDI in a pyridine/acetone solvent mix. Modified wood was... 

In the reaction of wood hydroxyls with isocyanates, a nitrogen-containing ester is formed. A limited reduction of fungal attack was reported earlier in beechwood modified with diisocyanate (13). Considerably more decay protection than acetylation has been shown in the methyl and allyl isocyanate modifications. Little decay was evident in methyl isocyanate-modified southern pine at WPGs between 14% and 19% in laboratory assay using G. trabeum. 

Cardias Williams, F. and Hale, M.D. (2003). The resistance of wood chemically modified with isocyanates the role of moisture content in decay suppression. International Biodeterioration and Biodegradation, 52(4), 215-221. 

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