Relation Between Moisture Sorption and Hygroexpansion of Sitka Spruce During Adsorption Processes


  • Erni Ma
  • Tetsuya Nakao
  • Guangjie Zhao
  • Hiroshi Ohata
  • Susumu Kawamura


Adsorption, dimensional change, moisture change


Moisture adsorption processes carried out in successive steps at three increasing levels of RH (45, 75, 85%) at 20°C for Sitka spruce (Picea sitchensis Carr.) were studied. Moisture content and dimensional changes in radial and tangential directions of the specimens were measured and it was found that moisture changes were slower than dimensional. The modeling on this moisture-dimensional relationship, based on the idea of dividing sorbed water into two components having different effects on dimensional changes, not only shows a good agreement with experimental results, but also presents a new understanding of the mechanism of hygroexpansion of wood.


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