炭化处理对杨木单板及胶合板物理力学性能的影响

Influence of carbonization treatment on physical and mechanical properties of poplar veneer and plywood

在不同炭化温度和时间下对杨木单板进行炭化处理,测定炭化单板的密度、含水率和平衡接触角,并将炭化单板热压制成5层对称结构胶合板,测定其密度、含水率、24 h吸水率、吸水厚度膨胀率和弯曲性能。结果表明:炭化杨木单板的密度和含水率均随着炭化处理条件的增强而减小;三聚氰胺改性脲醛树脂对单板的平衡接触角增大明显,说明单板炭化后润湿性减弱。与未处理材相比,炭化单板所制胶合板密度均有所增大,而胶合板的含水率变化不大;24 h吸水率和吸水厚度膨胀率随着炭化处理的增强明显减小;胶合板的弹性模量均有一定提高,而静曲强度则有所降低。单板炭化处理能较好地提高胶合板尺寸稳定性和弹性模量。

Poplar veneer was carbonization treated under different temperature and time conditions,and the treated veneer was hot pressed to 5-layer plywood. The density,moisture content,equilibrium contact angle of the treated veneer were tested, and density, moisture content, 24 h water absorption,thickness swelling and bending performance of the prepared plywood were tested. The results showed that the density and moisture content of the carbonization treated veneer declined with intensified treatment conditions.Equilibrium contact angle of the melamine modified urea-formaldehyde resin on the treated veneer increased significantly,indicating decreased wettability. Compared with the control plywood,the density of the treated plywood increased significantly,but its moisture content was less changed. The moisture absorption of plywood decreased significantly with intensified treatment conditions. The modulus of elasticity（ MOE） of the treated plywood increased while the modulus of rupture was decreased. It can be concluded that carbonization treatment improves the dimensional stability and MOE of poplar plywood.