Fluid Flow of Polar and Less Polar Liquids through Modified Poplar Wood

Abstract

Fast-growing species often have a low natural durability and can easily be attacked by fungi and insects, and therefore it is often better to preserve them before use. Permeability is a physical property in porous media that significantly affects the penetration of water- and oil-based preservatives into the texture of wood. In the present study, the specific gas permeability and liquid permeability to water and kerosene in poplar wood (Populus nigra var. betulifolia) were measured. The poplar trees were grown in plots with two spacings of 3 × 4 m and 3 × 8 m. Separate sets of specimens were also thermally modified in order to examinethe effects of this modification on gas and liquid permeability values. The results showed higher gas permeability in specimens grown in the plot with wider spacing (3 × 8 m), which was attributed to their larger vessel diameter. Kerosene demonstrated significantly higher permeability in comparison to water. This was attributed to the polar nature of water molecules, which tend to make stronger bonds with wood cell-wall polymers, ultimately delaying the movement of water through vessel elements. Thermal modification had an increasing effect on specific gas permeability. The increase was attributed to cracks that occur in the pits and wood cell wall during thermal modification, making way for the easier flow of fluids. Decreased wettability caused by thermal modification resulted in a significant increase in both water and kerosene permeability values.

Industrial Heat Treatment of Wood: Study of Induced Effects on Ayous Wood (Triplochiton scleroxylon K. Schum)

“…Another effect of heat treatment, as reported by [40], is the improvement of the wood permeability that allows a better penetration of polar and nonpolar compounds into the texture of the wood. This phenomenon is related to the reduction of the wettability of the material, due to the lower availability of free polar sites on the cell wall compounds, and this can increase the permeability of both water-based and oil-based preservative compounds, which can contribute to a further improvement of the material durability [40].…”