Characterisation of moisture sorption and transfer in Tunisian cork oak

This study characterised the mass-transfer properties and sorption behaviour of Tunisian cork. Density measurements reveal a sharp gradient from the outer bark (740 kg·m⁻³) to the inner cork layer (225 kg·m⁻³). Sorption isotherms indicate that the outer bark behaves similarly to solid oak wood, while the inner cork is slightly less hygroscopic. Due to its high porosity and the presence of radial lenticels, the dimensionless diffusivity factor of cork (fmean = 0.013 ±2.3×10−3) is about 6 times higher than that measured in the tangential direction of oak wood. Its radial gaseous permeability (Kmean = 4.4 × 10⁻¹³ m² ± 2 × 10⁻¹³) is also more than 10⁵ times higher. The transport properties were finally interpreted using equivalent-capillary parameters, enabling comparison with other porous materials. Cork has a relatively large effective pore radius and high tortuosity, reflecting the complex pathways actually used by moisture as it moves through the porous medium.