Effect of Microstructure on the Permeability and Sorption of Wood of Sterculia rhinopetala and Albizia ferruginea

Abstract

This paper sets to find out the effect of the microstructure of wood on the permeability and sorption of the wood of Sterculia rhinopetala and Albizia ferruginea. Permeability, the way of ingress of water into wood mass, is one of the most variable properties of timber and it further influences nearly all the physical properties of wood. Wood exposed to high humidity conditions or to liquid water during use may be subjected to biological deterioration which makes equilibrium moisture content of wood very important. Equilibrium moisture content is the moisture level where the wood neither gains nor loses moisture since it is at equilibrium with the relative humidity and temperature of the surrounding environment. Sixteen randomly sampled specimens of each of the wood of Sterculia rhinopetala and Albizia ferruginea species (heartwood and sapwood) with dimensions 3 cm x 3 cm x 3 cm were exposed at various relative humidity conditions of 30 %, 45 %, 60 %, 75 % and 90 % in a temperature and humidity-controlled climate chamber. The order of water uptake in terms of percentage volume is arranged from the lowest to the highest. Sterculia rhinopetala heartwood had the lowest uptake per volume with a value of 0.31 %. On the uptake per weight Sterculia rhinopetala heartwood again had the lowest uptake whilst Albizia ferruginea had the highest with a value of 6.77 %. The sapwood of Sterculia rhinopetala had a relatively higher uptake per volume value of 0.53 % and a value of uptake per weight of 0.72 %  compared to the heartwood. The equilibrium moisture content values of Sterculia rhinopetala suggests that it can have minimal dimensional changes when used in both the Southern and the Northern parts of Ghana.