高温热处理杨木再压缩工艺试验

The experiment on hot pressing process for thermally treated Populus tomentosa Carr. lumber

将毛白杨木材用195℃热处理3 h,然后用160℃的热压温度,分别在18%、26%、34%的压缩率下压缩保压10、25、40 min处理,研究了压缩率和保压时间对压缩木性能的影响。结果表明:试样的板面硬度在3个压缩率下分别提高31%、64%、88%,且出现随压缩时间延长而增加的趋势;静曲强度及弹性模量也随压缩率增加而增加,与压缩时间关系较小;弦向尺寸稳定性平均提高45%;吸水厚度膨胀率随压缩时间的减少及压缩率的提高而增大。综合结果较佳的处理工艺参数为:195℃热处理3 h,之后再用160℃温度26%压缩率保压25 min进行压缩处理,此时试样的物理性能接近水曲柳,弦向尺寸稳定性是水曲柳的1.9倍。

Poplar （Populus tomentosa Carr. ） lumber was thermally treated at 195℃ for 3 hours and then subjected to hot pressing at 160℃ .The compression sets and the pressure holding times were 18%, 26%, 34% and 10min, 25min, 40min, respectively. The influences of compression set and holding time on wood properties were studied. The results showed that surface hardness of the samples increased with the increasing of compression set and holding time, which was found 31% , 64% and 88% higher corresponding to the compression set of 18% , 26% and 34% , respectively. The modu-lus of elasticity and modulus of rupture also increased when higher compression sets were applied, but showed less correla-tion with holding time： The thickness swell increased when higher compression sets and less holding times were adopted. The average dimensional stability increased by 45%. The optimal compression ratio and holding time were 26% and 25min, respectively. Poplar wood treated in this condition exhibited similar physical properties to ash wood. Furthermore, its dimensional stability could be 1.9 times higher than ash wood.