| 预热温度对层状压缩木材力学性能的影响 |
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| 引用本文： | 李任,黄荣凤,常建民,高志强,伍艳梅.预热温度对层状压缩木材力学性能的影响[J].浙江农林大学学报,2018,35(5):935-941. |
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| 作者姓名： | 李任 黄荣凤 常建民 高志强 伍艳梅 |
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| 作者单位： | 1.中国林业科学研究院 木材工业研究所 国家林业局木材科学与技术重点实验室, 北京 1000912.北京林业大学 材料科学与技术学院, 北京 100083 |
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| 基金项目： | 国家自然科学基金资助项目31670557 |
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| 摘 要： | 不同预热温度下形成的层状压缩木材，因压缩层位置差异形成的不同结构及预热温度本身的变化均会引起力学性能变化。以毛白杨Populus tomentosa弦向板为材料，采用水热控制方法，通过改变预热温度获得了压缩层位于表层至中心层的不同结构的层状压缩木材。对其表面硬度、木材硬度、抗弯弹性模量与抗弯强度进行对比研究。结果表明:①随着预热温度的升高，木材表面硬度显著升高（P < 0.01），较对照的增加率为3.9%~57.2%，而木材硬度则极显著降低（P < 0.001），较对照的增加率为8.6%~38.5%。这个结果与压缩层随着预热温度升高，逐渐由表层向中心层移动形成的表层下0.32和2.82 mm厚度范围内木材的平均密度变化以及高温的作用密切相关。②随着预热温度的升高，弦向弯曲弹性模量逐渐增大，径向弯曲弹性模量逐渐减小；抗弯强度先增大，150℃后逐渐减小；但抗弯性能无显著差异（P>0.05）。不同预热温度下形成的层状压缩木材的力学性主要受其结构的影响，其次是温度的影响。控制压缩层的位置出现于木材表层，同时提高压缩层的密度，可获得力学性能更好的层状压缩木材。
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| 关 键 词： | 木材学 层状压缩木材 预热温度 木材表面硬度 木材硬度 抗弯弹性模量 抗弯强度 |
| 收稿时间： | 2017-09-14 |
Mechanical properties of preheated sandwich compressed wood |
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| LI Ren,HUANG Rongfeng,CHANG Jianmin,GAO Zhiqiang,WU Yanmei.Mechanical properties of preheated sandwich compressed wood[J].Journal of Zhejiang A&F University,2018,35(5):935-941. |
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| Authors: | LI Ren HUANG Rongfeng CHANG Jianmin GAO Zhiqiang WU Yanmei |
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| Affiliation: | 1.Key Laboratory of Wood Science and Technology of State Forestry Administration, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China2.College of Materials Science and Technology, Beijing Forestry University, Beijing 100083, China |
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| Abstract: | Changes in the position of compressed wood layers make the structure of sandwich compressed wood formed at different preheating temperatures vary with different structures affecting mechanical properties. In order to know how the structure of sandwich compressed wood affect its mechanical properties flat-sawn lumbers (thickness:25 mm) of Chinese white poplar (Populus tomentosa) were soaked in water and preheated on the hot plate at different temperatures as 90, 120, 150, 180 and 210℃, respectively. Then sandwich compressed woods with different structures were obtained. With an increase in preheating temperature, the position of the compressed layers moved gradually from the surface to the center layer. Analysis of the surface hardness, hardness, modulus of elasticity (MOE), and modulus of rupture (MOR) of the sandwich compressed wood was conducted. Results showed that (1) As preheating temperature increased, highly significant (F test, P < 0.01) surface hardness increases were found with a rate of increase of 3.9%-57.2% compared with that of untreated poplar wood. At the same time, decreases in hardness were highly significant (F test, P < 0.001) with the rate of increase of 8.6%-38.5% compared with that of untreated poplar wood. This was closely related to the effect of high temperatures and the change of average density for 0.32 and 2.82 mm thick wood in surface layers caused by compressed layers that were moved from the surface to the center layer as preheating temperature increased. (2) As preheating temperature increased, MOE and MOR changed but there were not significant differences (F test, P>0.05). All experimental results showed that mechanical properties of sandwich compressed woods were influenced mainly by their structure and then by the preheating temperature. Thus, sandwich compressed wood with better mechanical properties could be obtained by controlling compressed layers in surface layers and increasing the density of the compressed layers. |
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