Reaction of Isocyanates with Southern Pine Wood to Improve Dimensional Stability and Decay Resistance


  • W. Dale Ellis
  • Roger M. Rowell


Isocyanates, dimensional stability, decay resistance, southern pine


Ethyl, 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.


American Society for Testing and Materials. 1973. Standard method of testing wood preservatives by laboratory soil-block cultures. ASTM D 1413. Philadelphia, PA.nBaird, B. R. 1969. Dimensional stabilization of wood by vapor phase chemical treatments. Wood Fiber1(1):54-63.nBurmester, V. A., and C. Z. Olsen. 1971. Improvement of dimensional stabilization of beechwood by impregnation with diisocyanate after WAN-drying. Holzforschung25(3):84-89. (Ger.)nClermont, L. P., and F. Bender. 1957. The effect of swelling agents and catalysts on acetylation of wood. For. Prod. J.7(5):167-170.nRowell, R. M. 1980. Distribution of reacted chemicals in southern pine modified with methyl isocyanate. Wood Sci.13(2):102-110.nRowell, R. M., and W. D. Ellis. 1978. Determination of dimensional stabilization of wood using the water-soak method. Wood Fiber10(2):104-111.nRowell, R. M., and W. D. Ellis. 1979. Chemical modification of wood: Reaction of methyl isocyanate with southern pine. Wood Sci.12(1):52-58.nWakita, H., H. Onishi, S. Jodai, and T. Goto. 1977. Studies on the improvement of wood materials. XVIII. Vapor phase reaction of 2,4-tolylene diisocyanate in wood. Zairyo26(284):460-464.n






Research Contributions