Effect of heat treatment duration on the thermal conductivity of spruce and poplar wood

Changes in the thermal conductivity and density of Pannonia poplar (Populus x euramericana cv. Pannonia) and spruce (Picea abies) caused by heat treatment were examined. The specimens were treated at 180 °C for 15, 25 and 35 h. Treatment duration had different impact on both the density and the thermal conductivity of poplar and spruce. The density of poplar decreased by 9.1, 12.1 and 13.4%, and the thermal conductivity decreased by 16.9, 24.0, 29.1% after 15, 25 and 35 h of treatment, respectively. In the case of spruce, the density decreased by 5.2, 7.6 and 8.7%, and the heat conductivity by 7.4, 14.1 and 22.0%, respectively.