Effect of Pressurized Heat Treatment on Set-Recovery and Hardness of Surface-Compressed Wood

XIANG Elin; HUANG Rongfeng

doi:10.12326/j.2096-9694.2022199

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Effect of Pressurized Heat Treatment on Set-Recovery and Hardness of Surface-Compressed Wood
1.Research Institute of Wood Industry，Chinese Academy of Forestry，Beijing 100091，China
Vol. 37, Issue 3, Pages: 27-34(2023)
DOI： 10.12326/j.2096-9694.2022199

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向娥琳,黄荣凤.加压热处理对表层压缩木材变形回复及硬度的影响[J].木材科学与技术,2023,37(03):27-34.

XIANG Elin,HUANG Rongfeng.Effect of Pressurized Heat Treatment on Set-Recovery and Hardness of Surface-Compressed Wood[J].Chinese Journal of Wood Science and Technology,2023,37(03):27-34.
向娥琳,黄荣凤.加压热处理对表层压缩木材变形回复及硬度的影响[J].木材科学与技术,2023,37(03):27-34. DOI： 10.12326/j.2096-9694.2022199.

XIANG Elin,HUANG Rongfeng.Effect of Pressurized Heat Treatment on Set-Recovery and Hardness of Surface-Compressed Wood[J].Chinese Journal of Wood Science and Technology,2023,37(03):27-34. DOI： 10.12326/j.2096-9694.2022199.

摘要

木材表层压缩和加压热处理相结合是一种环保、低成本的物理改性方法，能显著提高低密度木材的硬度和尺寸稳定性。本研究对毛白杨（,Populus tomentosa,）边材试样进行表层压缩并形成干燥变定的压缩木，再用180 °C、0.1~0.7 MPa加压热处理永久固定压缩变形，分析表层压缩和蒸汽压力对压缩木压缩变形回复、硬度以及细胞壁微力学性能的影响规律。与未压缩材相比，当压缩率为20%时，压缩层的平均密度、表面硬度以及木材硬度分别提高了98%、70%、55%。蒸汽压力对固定压缩变形的效果极显著。当蒸汽压力为0.5 MPa时，吸湿状态下压缩变形完全不回复，吸水变形回复率降低至2.64%；当蒸汽压力增加至0.7 MPa，98%以上的压缩变形得到永久固定。随着蒸汽压力升高，表面硬度和木材硬度均呈先降低后增加的趋势，但差异在统计学上不显著。当蒸汽压力高于0.5 MPa时，纳米压痕测定的细胞壁弹性模量和硬度显著增加。

Abstract

The combination of surface compression and pressurized heat treatment is an environment friendly physical method for wood modification at a low cost, which significantly improve the hardness and dimensional stability of low-density wood. ,Populus tomentosa, sapwood was subjected to surface compression. The deformation produced was temporarily fixed after drying. Then, the pressurized heat treatment at 180 °C and 0.1~0.7 MPa was used to permanently fix the compressive deformation. The effects of surface compression and steam pressure on the set-recovery, hardness, and micromechanical behavior of poplar wood were investigated. Compared with uncompressed wood, when the compression ratio was 20%, the average density of the compressed layer, surface hardness, and hardness of surface-compressed wood (SC wood) were increased by about 98%, 70%, and 55%, respectively. The effect of steam pressure on the fixed compressive deformation was extremely significant. The pressurized heat treatment at 0.5 MPa blocks the compressive deformation to rebound under moisture absorption, while a reduction in set-recovery was 2.64% by immersion in water. When the pressurized heat treatment was at 0.7 MPa, it permanently fix the compressive deformation to 98%. With the increase of the steam pressure, the surface hardness and hardness decreased first and then increased, but the difference was not statistically significant. The pressurized heat treatment with a pressure of 0.5 MPa significantly improve the elasticity modulus and hardness of cell walls measured by nanoindentation.

关键词

木材表层压缩加压热处理变形回复硬度

Keywords

woodsurface compressionpressurized heat treatmentset-recoveryhardness

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