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Journal of Wood Science

, Volume 64, Issue 6, pp 751–757 | Cite as

Effects of preheating temperatures on the formation of sandwich compression and density distribution in the compressed wood

  • Ren Li
  • Zhiqiang Gao
  • Shanghuan Feng
  • Jianmin Chang
  • Yanmei Wu
  • Rongfeng Huang
Original Article
  • 86 Downloads

Abstract

Sandwich compression of wood that can control the density and position of compressed layer(s) in the compressed wood provides a promising pathway for full valorization of low-density plantation wood. This study aims at investigating the effects of preheating temperatures (60–210 °C) on sandwich compression of wood, with respect to density distribution, position and thickness of the compressed layer(s). Poplar (Populus tomentosa) lumbers with moisture content below 10.0% were first soaked in water for 2 h and stored in a sealed plastic bag for 18 h, the surface-wetted lumbers were preheated on hot plates at 60–210 °C and further compressed from 25 to 20 cm under 6.0 MPa at the same temperature on the radial direction. The compressed lumbers were characterized in terms of density distribution, position and thickness of compressed layer(s). It was found that depending on preheating temperatures, sandwich compressed wood with three structural modes, namely, surface compressed wood, internal compressed wood and central compressed wood can be formed. Density of the compressed layer(s) in wood increased gradually as a result of the elevated preheating temperatures. Higher preheating temperatures gave rise to bigger distance between compressed layer(s) and the surface, and preheating temperature elevation from 90 to 120 °C contributed to a maximal distance increase of 2.71 mm. In addition, higher preheating temperatures resulted in bigger thickness of compressed layer(s) over 60–150 °C and temperature elevation from 120 to 150 °C lead to the layers integration from two into one. Further temperature elevation over 150 °C reduced the thickness of the compressed layer in wood. SEM scanning suggested that cell wall bucking rather than cell wall crack occurred in compressed layer(s) and transition layer(s).

Keywords

Sandwich compression Preheating temperature Position of the compressed layer(s) Thickness of the compressed layer(s) Density distribution 

Notes

Acknowledgements

The authors acknowledge the financial support from the National Natural Science Foundation of China: Formation Mechanism and Controllability of Wood Sandwich Compression by Hydro-thermal Control (Grant no. 31670557).

References

  1. 1.
    Kitamori A, Jung K, Mori T, Komatsu K (2010) Mechanical properties of compressed wood in accordance with the compression ratio. Mokuzai Gakkaishi 56:67–78CrossRefGoogle Scholar
  2. 2.
    Tu DY, Su XH, Zhang TT, Fan WJ, Zhou QF (2014) Thermo-mechanical densification of populus tomentosa var. tomentosa with low moisture content. Bioresources 9:3846–3856Google Scholar
  3. 3.
    Zhan JF, Avramidis S (2017) Transversal mechanical properties of surface-densified and hydrothermally modified needle fir wood. Wood Sci Technol 51(4):721–738CrossRefGoogle Scholar
  4. 4.
    Huang RF, Wang YW, Zhao YK, Lu JX (2012) Sandwich compression of wood by hygro-thermal control. Mokuzai Gakkaishi 58:84–89CrossRefGoogle Scholar
  5. 5.
    Furuta Y, Nakajima M, Nakanii E, Ohkoshi M (2010) The effects of lignin and hemicelluloses on thermal-softening properties of water-swollen wood. Mokuzai Gakkaishi 56:132–138CrossRefGoogle Scholar
  6. 6.
    Åkerholm M, Salmén L (2004) Softening of wood polymers induced by moisture studied by dynamic FTIR spectroscopy. J Appl Polym Sci 94:2032–2040CrossRefGoogle Scholar
  7. 7.
    Simpson WT, Lin JY (1991) Dependence of the water vapor diffusion coefficient of aspen on moisture content. Wood Sci Technol 26:9–21CrossRefGoogle Scholar
  8. 8.
    Hrčka R, Babiak M, Németh R (2008) High temperature effect on diffusion coefficient. Wood Res Slovak 53:37–46Google Scholar
  9. 9.
    Li YJ, Li L, Zhang BG (2007) Moisture diffusion coefficient of Cunninghamia lanceolate board with non-steady state conditions. J Zhejiang Fore Coll 24:121–124Google Scholar
  10. 10.
    Udaka E, Furuno T (2005) Relationships between pressure in a closed space and set recovery of compressive deformation of wood using a closed heating system. Mokuzai Gakkaishi 51:153–158CrossRefGoogle Scholar
  11. 11.
    Pang S (1997) Some considerations in simulation of superheated steam drying of softwood lumber. Drying Technol 15:651–670CrossRefGoogle Scholar
  12. 12.
    Hunter AJ (1993) On movement of water through wood—the diffusion to efficient. Wood Sci Technol 27:401–408CrossRefGoogle Scholar
  13. 13.
    Gao ZQ, Zhang YM, Wu ZQ, Wang YW, Li R, Huang RF (2017) Effect of pressurized heat treatment on spring-back of surface compressed poplar wood. China Wood In 31:24–28Google Scholar
  14. 14.
    Haque MN (2007) Analysis of heat and mass transfer during high-temperature drying of Pinus radiata. Drying Technol 25:379–389CrossRefGoogle Scholar
  15. 15.
    Yokoyama M, Kanayama K, Furuta Y, Norimoto M (2000) Mechanical and dielectric relaxations of wood in a low temperature range III. Application of sech law to dielectric properties due to adsorbed water. Mokuzai Gakkaishi 46:173–180Google Scholar
  16. 16.
    Beard JN, Rosen HN, Adesanya BA (1983) Temperature distribution and heat transfer during the drying of lumber. Dry Technol 1:117–140CrossRefGoogle Scholar
  17. 17.
    Beard JN, Rosen HN, Adesanya BA (1985) Temperature distribution in lumber during impingement drying. Wood Sci Technol 19:277–286CrossRefGoogle Scholar
  18. 18.
    Tang YF, Pearson RG, Hart CA, Simpson WT (1994) A numerical model for heat transfer and moisture evaporation processes in hot-press drying—an integral approach. Wood Fiber Sci 26:78–90Google Scholar
  19. 19.
    Fotsing JAM, Tchagang CW (2005) Experimental determination of the diffusion coefficients of wood in isothermal conditions. Heat Mass Transfer 41:977–980CrossRefGoogle Scholar
  20. 20.
    Inoue M, Norimoto M, Otsuka Y, Yamada T (1990) Surface compression of coniferous wood lumber I. A new technique to compress the surface layer. Mokuzai Gakkaishi 36:969–975Google Scholar

Copyright information

© The Japan Wood Research Society 2018

Authors and Affiliations

  • Ren Li
    • 1
    • 2
  • Zhiqiang Gao
    • 1
    • 2
  • Shanghuan Feng
    • 3
  • Jianmin Chang
    • 2
  • Yanmei Wu
    • 1
  • Rongfeng Huang
    • 1
  1. 1.Research Institute of Wood IndustryChinese Academy of ForestryBeijingPeople’s Republic of China
  2. 2.College of Materials Science and TechnologyBeijing Forestry UniversityBeijingPeople’s Republic of China
  3. 3.Department of Energy TechnologyAalborg UniversityAalborg ØstDenmark

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