Vacuum infusion as a novel method to determine wood permeability

Abstract

This study aims to propose a novel method, vacuum infusion process, to measure the longitudinal permeability of wood. The vacuum infusion method uses a vacuum bag sealed over the fibrous material, with a vacuum inlet and a vacuum outlet. It can be performed on top of any flat surface, and its process is relatively swift. Six different woods (Pinus elliottii, Araucaria angustifolia, Ochroma pyramidale, Cedrela fissilis, Tectona grandis, and Eucalyptus grandis) and three different fluids (water, soybean oil, and furfuryl alcohol) were selected for the study. After preliminary evaluations of morphology, chemical characteristics, density, porosity, contact angle and capillary pressure, three woods and two fluids were selected for the actual permeability measurements. The highest permeability was obtained for the Ochroma pyramidale wood, being 0.45–7.49 × 10–11 m2. This wood was 58–88% and 18–62% more permeable than the Pinus elliottii and Eucalyptus grandis woods, respectively. The fluid was found to have some influence on the experiment and therefore must be carefully selected. The difference in permeability of the woods was attributed to morphological characteristics, especially the presence of axial vessels, which are 60% larger for Ochroma pyramidale wood compared to Eucalyptus grandis wood, while Pinus elliottii has no vessels. The amount of voids in all woods, nevertheless, was similar, as well as the evaluated chemical characteristics and structural anatomical elements (tracheids and/or fibers). In all, the determination of apparent permeability using the vacuum infusion process is practical and with good accuracy, yielding results similar to those from other methods in the literature.