Effect of steam-heat treatment on mechanical properties of Chinese fir

Heat treatment often brings about some negative effects on mechanical properties of wood. Chinese fir is currently underutilized due to some inherent properties that limit its further applications. Using steam as a heating medium and a shielding gas, the heartwood and sapwood of Chinese fir were treated at a temperature ranging from 170 degrees C to 230 degrees C and time from 1 to 5 hours in an airtight chamber. Both the modulus of rupture (MOR) and modulus of elasticity (MOE) were increased for the sapwood specimens under the temperature less than 200 degrees C for short treatment times. The hardness was increased for both two kinds of specimens under the temperature less than or about 200 degrees C, compared to the untreated specimens. The temperature has a stronger effect on mechanical properties of wood than the time, and the temperature of 200 degrees C is a critical point in modifying mechanical properties of wood.