Air permeability in longitudinal and radial directions of compression wood of Picea abies L. and tension wood of Fagus sylvatica L.

Abstract

The air permeability in longitudinal and radial directions of compression wood in spruce (Picea abies) and tension wood in beech (Fagus sylvatica) was compared with that of the corresponding normal wood. The primary aim of the present study was to explain why the reaction woods dry more slowly than the normal woods in the domain of free water. A number of boards conventionally dried to an average final moisture content of 12% were chosen to perform the measurements. Bordered pits on the radial walls of longitudinal tracheids in the compression and normal wood and intervessel or intervascular pits in the tension and normal wood were also examined. The reaction wood of both species is less permeable than the normal wood, both in longitudinal and radial directions. The difference in permeability was more pronounced between compression and normal wood of spruce, especially in longitudinal direction. From an anatomical point of view, this is likely related to some differences in anatomical characteristics affecting the airflow paths, such as the pit features. Such results can explain the difference in drying kinetics of the reaction and normal woods in the capillary regime of drying.

RELATIONSHIP BETWEEN THE ANATOMY AND DRYING IN Eucalyptus grandis X Eucalyptus urophylla WOOD

“…Lumen diameter and cell wall thickness influenced the wood drying in different way (KOLLMANN;CÔTÉ, 1968;TARMIAN;PERRÉ, 2009). These parameters can be related to only one variable, the cell wall fraction, which showed a greater relationship with drying.…”

Microwave Treatment for Enhancing the Liquid Permeability of Chinese Fir

“…The water uptake of MW-treated samples with unsealed ends after impregnation for 15 min at a pressure of 0.8 MPa is very similar to that of the control samples (Table 2). This may be caused by the fact that the dimensions of the samples were relatively small; there is a significantly different permeability along the longitudinal and transverse directions, and the liquid flow in the transverse direction (tangential and radial directions) is much lower than that of the flow in the longitudinal direction (Tarmian and Perre 2009). Although the weak ray cells are ruptured to form pathways for easy transportation of liquids, resulting in an increase of permeability in the transverse direction during MW treatment (Torgovnikov and Vinden 2009), the increase in the permeability in the transverse direction was moderate compared to the rapid flow in the longitudinal direction when the ends of the samples were unsealed.…”

Changes in viscoelastic vibrational properties between compression and normal wood: roles of microfibril angle and of lignin

“…The peculiarities of CW were also demonstrated by gene expression studies during wood formation (Yamashita et al 2009). In general, CW attracted a lot of attention also in the last decade concerning lignin deposition in the S2 layer (Yoshizawa et al 1999), air permeability (Tarmian andPerré 2009), lignin structure (Önnerund 2003), shear strength (Gindl and Teischinger 2003), morphological and chemical variations (Yeh et al 2006), characterisation of galactans by immunofluorescece (Altaner et al 2007), relation of MFA and lignin content (Jungnikl et al 2008), and ultrastructure (Hänninen et al 2012), just to mention a few. Thus CW is well known and the pair CW/NW is well suited for the investigation of the combined influence of specific gravity, MFA, and chemistry of the cell wall polymers on mechanical properties of wood.…”