Effects of Heat Treatment on some Physical Properties of Douglas Fir (Pseudotsuga Menziesii) Wood

In this study the effect of heat treatment on some physical properties of Douglas fir (Pseudotsuga menziesii) was investigated. Wood specimens were subjected to heat treatment at 160, 180, 200 and 220°C for 1, 2, 3 and 4h. The results show that heat treatment resulted in a darkened color, decreased moisture performance and increased dimensional stability of wood. Compared with untreated wood, equilibrium moisture content (EMC), water absorption (WA) and volume swelling (VS) for treated wood decrease up to 42.63%, 34.93% and 67.47%. The higher the treatment temperature and the longer the treatment time, the lower EMC, WA and VS. The VS of treated specimens has a more significant reduction than EMC and WA when the heat treatment temperature is above 180°C. The visual color changes were more distinct after heat treatment above 180°C. Temperature has a greater influence than time on these properties of specimens.