Physical, Mechanical, and Thermal Properties of Heat- Treated Poplar and Beech Wood

Air-dried density, weight loss (WL), impact bending strength (IBS), Shore- D hardness, and thermal conductivity values were determined for heat- treated poplar ( Populus nigra L.) and beech ( Fagus orientalis Lipsky) wood and compared with those for untreated samples. The test samples were heat-treated at 140, 160, 180, and 200 degrees C for 2 h. The results showed that density decreased and WL increased with increasing temperature for all temperatures. Additionally, during the heat treatment, the IBS increased in beech wood samples at 140 degrees C, but at higher temperatures, these values gradually decreased in both wood species. The highest decline in IBS values, found at a temperature of 200 degrees C, was 66.5% for beech and 55.7% for poplar. The Shore-D hardness of both wood species increased after heat treatment and regarding beech wood, the hardness increasing rate at temperature at 140 degrees C, 160 degrees C, 180 degrees C and 200 degrees C, 8.94%, 14.19%, 8.27% and 11.7%, respectively according to control samples. Regarding poplar wood, hardness increasing rates were 6.20% at 140 degrees C, 4.41% at 160 degrees C, 5.88% at 180 degrees C and 5.31% at 200 degrees C according to control samples. The thermal conductivity of poplar and beech wood samples decreased after heat treatment, except for samples heat treated at 160 degrees C.