Densification of wood veneers by compression combined with heat and steam

摘要: Wood veneer 700×700 mm2 specimens made with aspen (Populus tremuloides) and hybrid poplar clone 15303 maximowiczii × Populus balsamifera) were densified using heat, steam, pressure. Temperatures of 140, 160, 180, 200, 220°C applied at a maximum steam pressure 550 kPa press hydraulic ranging from 4.5 to 9.0 MPa. After densification, the oven-dry density increased significantly, veneers darkened, lathe checks that present on before densification conglutinated surface roughness decreased. Densified showed markedly reduced hygroscopicity: higher temperature, lower wood hygroscopicity. The Brinell hardness was about two three times control for both poplar. Tensile bending strength also significantly after densification. However, mechanical properties decreased slightly temperature. modulus elasticity in tension especially high temperatures. A very compression set recovery found low Recovery dramatically when temperature exceeded 180°C. Almost no 220°C.