Evaluation of Applied Performance of Thermally-Modified Fir Wood by Retification Process

In this research, Fir wood (Abies spp.) was thermally modified by retification process. The effect of modification process on physical and mechanical properties of fir wood were evaluated. For this aim, fir wood specimens with 12% moisture were modified in the steel tank with nitrogen gas medium at different temperatures (180 °C, 200 °C, and 220 °C) and 15 hours holding time. Physical properties such as wood density, volumetric swelling, dimensional stability and mechanical properties such as modulus of rupture (MOR), modulus of elasticity (MOE), shear and compression strength parallel to grain and impact strength of different modified wood specimens were evaluated. Results showed that by increasing treatment temperature, during modification process, water absorption and volumetric swelling were decreased and dimensional stability was improved. Also, results revealed that the mechanical strength of modified wood such as MOR, MOE, shear and compression strength parallel to grain and impact strength were decreased.