Hygroscopic properties and dimensional stability of cork oak wood

• Autores: Vicelina Sousa, Sofia Leal, Helena Pereira
• Localización: Suberwood: new challenges for the integration of cork oak forests and products / Javier Vázquez Piqué (ed. lit.), Helena Pereira (ed. lit.), María Arantzazu González Pérez (ed. lit.), 2008, ISBN 978-84-96826-47-2, págs. 341-350
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • The wood behaviour, i.e. the dimensional variation, is related to its equilibrium moisture content which depends on wood-environment exchanges. This aspect is very important for wood processing mainly if a high quality wood utilization is envisaged. The drying process is a crucial stage to obtain a final quality wood product and most of the drying defects can be avoided if the process is performed according to the properties of the wood and to the conditions it will be exposed to while in use. Variations in wood moisture content, density and dimensions were studied at three temperatures, 22°C; 15°C and 27°C, representing average conditions inside acclimatized homes, and winter and summer inside non-acclimated homes, respectively. For each temperature air humidity varied from 95% to 10%. Equilibrium moisture content and drying curves were also built. Total volumetric shrinkage varied between 12.5-16.2% while volumetric shrinkage coefficient ranged from 0.43-0.59%. The wood showed some anisotropy regarding the linear dimensional variation: in the tangential direction, the shrinkage was moderate at 7.5-9.9%, and low in the radial direction at 3.5-4.3% and at 0.7-1.6% in the axial direction. Wood density at 12% moisture content varied from 0.63-0.67 g/cm3. The higroscopicity was 0.003. The fiber saturation point ranged from 25.1-31.7%. With regard to dimensional variability there were no significant differences in wood moisture content and in density between the three temperatures. Therefore the cork oak wood may be classified as a heavy wood, showing a medium fiber saturation point and higroscopicity. The anisotropy in dimensional variation and the total volumetric shrinkage should be taken into account when designing drying programs and wood components.