Cork oak (Quercus suber L.) wood hygroscopic properties and dimensional stability

Abstract

Cork oak (Quercus suber L.) wood has a potential for high value uses because of its strength and aesthetic properties but one obstacle is the lack of knowledge of the wood-water relations. Variations in wood equilibrium moisture content, density and dimensions were studied at air temperatures of 22°C and 27°C (representing acclimatized homes and summer non-acclimatized homes, respectively) varying from 80% to 30% of relative humidity.For indoor uses (22-27°C, 50-65% of relative humidity), the wood equilibrium moisture content ranged 12-17% and these values are recommended for the final commercial drying of cork oak wood. The fibre saturation point averaged 27%. Total volumetric shrinkage at 22°C-27°C averaged 12%, the linear shrinkage 8.1-8.5% and 3.6-3.6%, respectively in tangential and radial directions. Anisotropy averaged 2.3. Wood density at 12% moisture content ranged 0.63 to 0.67 g/cm 3 . The higroscopicity obtained was 0.003. The average tangential differential shrinkage was 0.32 for both temperatures and the average radial differential shrinkage was 0.14 and 0.15, at 22°C and 27°C respectively. The shrinkage factor was 0.90 cm 3 /g and 0.82 cm 3 /g, at 22°C and 27°C respectively. Differences between temperatures were only statistically significant at 80-70% of relative humidity.Key words: Cork oak; moisture content; hygroscopicity; Quercus suber; shrinkage. ResumenPropiedades higroscópicas y de estabilidad dimensional de madera de alcornoque (Quercus suber L.)La madera de alcornoque tiene potencial para usos de alto valor debido a su resistencia y propiedades estéticas, pero presenta un obstáculo como es la falta de conocimiento de las relaciones agua-madera. Se han estudiado las variaciones en el contenido de humedad de equilibrio de la madera, la densidad y las dimensiones a temperaturas del aire de 22°C y 27°C (que representa casas climatizadas y casas de verano no aclimatadas, respectivamente) variando entre 80% a 30% de humedad relativa. Para usos interiores (22-27° C, 50-65% de humedad relativa), el equilibrio de humedad de la madera osciló entre el 12-17% y se recomiendan estos valores para el secado final de la madera comercial de alcornoque. El punto de saturación de la fibra promedio es del 27%. La contracción volumétrica total a 22°C-27°C en promedio es de un 12%, la contracción lineal varía entre 8.1-8.5% y 3.6-3.6%, respectivamente en direcciones tangenciales y radiales. La anisotropía promedio fue de 2,3. La densidad de la madera con un contenido de humedad del 12% varió entre 0,63 a 0,67 g/cm 3 . La higroscopicidad obtenida fue de 0,003. La contracción diferencial tangencial promedio fue de 0,32 para ambas temperaturas y la contracción radial diferencial promedio fue de 0,14 y 0,15, a 22°C y 27°C respectivamente. El factor de contracción fue de 0,90 cm 3 /g y 0,82 cm 3 /g, a 22°C y 27°C respectivamente. Las diferencias entre las temperaturas fueron estadísticamente significativas sólo al 80-70% de humedad relativa.

Age trends and within-site effects in wood density and radial growth in Quercus faginea mature trees

“…Zhang et al, 1993;Guilley et al, 1999Guilley et al, , 2004Bergès et al, 2008), but other oaks have also attracted attention, namely species growing in more southern regions (e.g. Knapič et al, 2008;Leal et al, 2012).…”

Anatomical characterization, physical, and chemical properties of wood of Quercus macdougallii Martínez, endemic species of the Sierra Juárez of Oaxaca, Mexico

“…In the densities analyzed, it was observed that they decrease when the height in the stem increases (Table 5). Knapic et al (2011) and Leal et al (2012) found similar behavior in Quercus faginea and Q. suber L., respectively. The anhydrous density of sapwood wood according to the mean is like the reports for Q. sartorii and Q. mexicana wood .…”

“…This causes a reduction in the permeability of the wood, so the moisture content is low. The behavior presented in the wood of Quercus suber L. is the opposite to this convention (Leal et al 2012).…”

“…The FSP according to the average is classified as high (Sallenave 1955), in which similar values have been reported for Quercus robur wood (Kolin and Janezic 1996), Q. convallata Trel. , and Q. suber L. (Leal et al 2012).…”

Some of Phenotypic, Physical and Anatomical Wood Properties of Valonia Oak Trees in Kurdistan-Iraq

“…Which differ in values reported for Q. convallata Trel. (22), Q. suber L. (28), and Q. macdougallii Martínez (39). Moreover, it was noted that Q. aegilops has a very high proportion of the cell wall (55.24%).…”