杨木单板的湿热处理对单板层积材性能的影响

杨木单板的湿热处理规律以及对杨木单板层积材性能影响的研究结果表明,单板湿热处理后产生了塑化,形成了一部分不可恢复的变形,密度平均增加了38.7%;对抗拉强度的影响不显著;对单板压缩率和膨胀率有着特别显著的影响,单板平均压缩了27.8%,经24h水浸泡,单板恢复膨胀仅18.7%.单板湿热处理后经过低压压制,可以得到与高压压制相同密度的板材,且板材的断面密度差异小,水平剪切强度提高了27.1%,静曲强度增加了17.8%,弹性模量没有显著变化,吸水厚度膨胀率降低了约10个百分点.

Effect of the Hygrothermal Treatment of Poplar Veneer on Laminated Veneer Lumber

The rules of hygrothermal in poplar veneer and the effects of laminated veneer lumber were studied. The results showed that a little plastic deformation occurred in poplar veneer, in average density increased 38.7%, and it has less effect on tension strength of veneer. Obvious effects of hygrothermal treatment is on thickness compress ratio and swelling ratio. The around thick compress ration is 27.8% , while thickness swelling ration in water is 18.7% after 24h. Using hygrothermal treated veneer , LVL in the similar density can be made not only under high pressure process but also by using low pressure. Treated veneer of LVL with low pressure process showed low cross density gradient, and liner shear strength up to 27. 1% , MOR increasing 17.8%, adsorption water swelling decreasing 10%. However, MOE of LVL from treated veneer had no obvious change.