This study was carried out to use carbonized medium density fiberboard (MDF) for the replacement of sound absorbing material. Carbonization treatment was performed to improve sound absorption property for MDF at carbonizing temperatures of 500℃, 700℃, 900℃ and 1100℃. As the carbonization temperature increased, the results of the observation by scanning electron microscope (SEM) demonstrated that the fibers exhibited a more compressed morphology within the surface section of the MDF than those within the middle section of MDF. As the carbonizing temperature increased, the cavity increased. The sound absorption coefficient increased between the temperatures of 500℃ and 900℃, but decreased at a temperature of 1100℃. The sound absorption properties of the carbonized MDF and the non-carbonized MDF were compared. The maximum sound absorption coefficient of the carbonized MDF was 12.38%. This was almost double of the value of the non-carbonized MDF.

To evaluate the resistance of wood to decay caused by fungi, sapwood and heartwood of red pine (Pinus densiflora) and sapwood and heartwood of larch (Larix kaempferi) were conducted. Wood samples were immersed for 96 h in pyroligneous liquor. Then, the brown-rot fungus, Fomitopsis palustris, was used to examine the decay resistance of red pine and larch. Weight and density of wood from the all conditions increased after immersion treatment. Weight loss after decay resistance test was also dropped with a immersion treatment. The lowest weight loss indicated at immersion-treated heartwood of larch. Immersion treatment using pyroligneous liquor effectively increased the resistance of wood to decay caused by fungi.

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