Decay and termite resistance, water absorption and swelling of thermally compressed wood panels

This study evaluated decay and termite resistance of thermally compressed pine wood panels under pressure at either 5 or 7 MPa and either 120 or 150 °C for 1 h. Wood specimens from the panels were exposed to laboratory decay resistance tests by using the wood degrading fungi, Gloeophyllum trabeum and Trametes versicolor. The thermal compression process caused increases in density and decreases in thickness of the panels; however, laboratory decay resistance tests revealed that thermally compressed wood was not resistant against the wood degrading fungi tested. More interesting results were found in laboratory termite resistance tests by using the Eastern subterranean termites, Reticulitermes flavipes. As pressure and temperature applied to the specimens increased to 7 MPa and 120 °C, mass losses in the specimens gradually decreased in comparison with control specimens. However, the specimens compressed at 7 MPa and 150 °C showed higher mass losses when compared to the specimens compressed at 7 MPa and 120 °C. The lowest water absorption and swelling rates were seen in the specimens exposed to a pressure of 7 MPa at 120 °C. The thermal compression process at 7 MPa and 150 °C resulted in the highest water absorption and swelling in the specimens.