Reaction of Isocyanates with Southern Pine Wood to Improve Dimensional Stability and Decay Resistance
Keywords:Isocyanates, dimensional stability, decay resistance, southern pine
AbstractEthyl, n-propyl, and n-butyl isocyanates reacted with wood without catalyst to yield modified southern pine that was 30 to 50% more dimensionally stable than unmodified specimens and that had improved decay resistance. Phenyl and p-tolyl isocyanates and 1,6-diisocyanatohexane, isophorone diisocyanate, and tolylene-2,4-diisocyanate formed nonbonded polymers in wood voids and did not increase dimensional stability. In the presence of 35% dimethylformamide, however, n-butyl and phenyl isocyanates, 1,6-diisocyanatohexane and tolylene-2,4-diisocyanate reacted with wood, resulting in increased dimensional stability. The best dimensional stability and decay resistance of all specimens tested were shown by those modified with n-butyl isocyanate in the presence of 35% dimethylformamide. The dimensional stability was 70% better than that of unmodified specimens and the weight lost in the decay test was 2%, indicating a high resistance to decay.
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