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Journal of Wood Science

, Volume 64, Issue 6, pp 730–737 | Cite as

Moisture state variety in poplar lumber with moisture content above fibre saturation point during hot-press drying

  • Junfeng Hou
  • Songlin Yi
  • Yongdong ZhouEmail author
  • Bin Pan
Original Article
  • 132 Downloads

Abstract

Hot-press drying has gained attention due to its excellent drying rate and surface strengthening effect. The moisture state in poplar lumber (Populus tomentosa) with moisture content (MC) above fibre saturation point (FSP) was analyzed during hot-press drying. The effect of heating platens’ temperature on the temperature and pressure inside poplar lumber was investigated. The moisture state changes inside the poplar lumber during hot-press drying were further analysed in accordance with the measured pressure and theoretical pressure calculated with the measured temperature inside poplar lumber. Results were as follow: When the heating platens’ temperature increased from 120 to 140 °C, the maximum values of temperature and pressure also increased by 14.5 and 26.2%, respectively. However, a delay occurred between the maximum values of pressure and temperature. The moisture at the center layer of poplar lumber with MC above FSP was in liquid state, i.e. unsaturated water under overpressure condition in hot-press drying process. Flashing occurred to the unsaturated water in poplar lumber during the opening period of heating platens and resulted in the decrease in MC. This phenomenon is the main moisture transfer mode in wood hot-press drying process with MC above FSP.

Keywords

Popluous tomentosa Hot-press drying Temperature Pressure Moisture state 

Notes

Acknowledgements

This work was financial supported by the National Forestry Industry Research Special Funds for Public Welfare Projects from State Forestry Administration of China (no. 201404502).

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Copyright information

© The Japan Wood Research Society 2018

Authors and Affiliations

  • Junfeng Hou
    • 1
    • 2
  • Songlin Yi
    • 2
  • Yongdong Zhou
    • 1
    Email author
  • Bin Pan
    • 1
  1. 1.Research Institute of Wood IndustryChinese Academy of ForestryBeijingPeople’s Republic of China
  2. 2.College of Material Science and TechnologyBeijing Forestry UniversityBeijingPeople’s Republic of China

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