Biogenic Formaldehyde: Content and Heat Generation in the Wood of Three Tree Species

Global trends in allowable formaldehyde (CH2O) emissions from nonstructural wood-based composites require a renewed consideration of biogenic CH2O from wood. Increment cores from living Virginia pine (Pinus virginiana), yellow-poplar (Liriodendron tulipifera), and radiata pine (P. radiata) trees were used to measure CH2O and CH2O generation due to heating (200 degrees C, 10 min). Significant variations within and between trees of the same species were observed. Tissue types (juvenile/mature, heartwood/sapwood) sometimes correlated to higher CH2O contents and greater heat-generation potential; however, this did not always depend upon species. Heating increased CH2O levels 3-60-fold. Heating with high moisture levels generated more CH2O than that generated from dry specimens. Radiata pine generated extraordinarily high CH2O levels when heated, far exceeding the other species. It was suggested that pine extractives might catalyze CH2O generation, perhaps in lignin. Regarding wood-based composites, findings suggested that compliance with emissions regulations may be complicated by CH2O generated in the hot press. If we could reveal the precise mechanisms of CH2O generation in wood, we could perhaps manipulate these mechanisms for beneficial purposes.