Pyrolysis, Leach Resistance, Hygroscopicity, and Decay Resistance of Wood Treated with Organophosphorus Esters in Combination with Isophorone Diisocyanate


  • W. Dale Ellis


Flame retardant, Fyrol 6, Fyrol 51, organophosphorus esters, isophorone diisocyanate, wood, hygroscopicity, decay resistance


This study evaluated the effectiveness of a difunctional isocyanate to improve the performance of organophosphorus flame retardants. Small southern pine specimens were reacted with isophorone diisocyanate in combination with two organophosphorus ester compounds. The resulting treatments were leach-resistant, not hygroscopic, and moderately decay-resistant, and had thermal degradation patterns like those of effective flame retardants. Pyrolysis of the treated specimens showed lower temperatures at the maximum rate of pyrolysis and greater amounts of residual char compared to untreated specimens. Treated specimens had 2% to 3% less equilibrium moisture content at 27 C and 80% relative humidity than did the untreated specimens. The most leach-resistant specimens lost less than 20% phosphorus during water extraction. This loss of phosphorus did not appreciably change the thermal degradation of the specimens. The treated specimens were more decay-resistant than the untreated ones.


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