In situ measurement of heat-treated wood cell wall at elevated temperature by nanoindentation

Published Date
September 2016, Vol.87:142–149, doi:10.1016/j.indcrop.2016.04.017

Title 
In situ measurement of heat-treated wood cell wall at elevated temperature by nanoindentation

Author 

Dong Xing ^a,b

Jian Li ^a

Xinzhou Wang ^b,c

Siqun Wang ^b,,

• aCollege of Materials Science and Engineering, Northeast Forestry University, Harbin 150040, PR China
• bCenter for Renewable Carbon, University of Tennessee, Knoxville, TN 37996, USA
• cCollege of Materials Science and Engineering, Nanjing Forestry University, Nanjing 210037, PR China

Received 18 September 2015. Revised 25 March 2016. Accepted 3 April 2016. Available online 22 April 2016.

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Highlights

• •
  Nanoindentation was equipped with temperature control stage to achieve the real-time test at elevated temperature conditions.
• •
  The 3D morphology of wood cell wall and compound middle lamella were recorded by scanning probe microscopy.
• •
  XRD and SEM were used to detect the microstructure and crystallinity of heat-treated wood.
• •
  The micromechanical properties of wood cell wall were discussed at elevated temperature condition.
• •
  This study supplies the fundamental research of viscoelastic properties of heat-treated wood cell wall.

Abstract

Nanoindentation equipped with hot stage to investigate the temperature-dependent real-time mechanical behavior of wood cell wall is introduced. In this study, wood samples were heat-treated at 180 °C and 210 °C. The effects of heat treatment on Larix gmelinii (Rupr.) Kuzen, a species of larch native to eastern Siberia, were studied at the cell-wall level. Nanoindentation at high temperature was used to track changes in the micromechanical properties in the longitudinal direction and to obtain measurements for both the temperature-dependent reduced modulus and hardness. The average reduced modulus of the cell wall slightly increased, while hardness tended to increase after heat treatment under room temperature conditions. The nanoindentation tests showed that both the reduced modulus and hardness of the wood cell walls tended to decrease as the temperature increased from 20 °C to 180 °C. Moreover, it was shown that heat treatment resulted in better heat resistance compared to that of untreated wood, especially in the samples indented at 180 °C.

Keywords

• Cell wall
• Heat-treated wood
• Nanoindentation
• Real-time
• Creep

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  Corresponding author at: Center for Renewable Carbon, Department of Forestry, Wildlife and Fisheries, University of Tennessee, Jacob Drive, Knoxville, TN 37996, USA.