Influence of cyclic sorption on wood ultrastructure

Abstract

Desorption and adsorption cycles result in dimensional changes of wood. The shrinkage and swelling of wood components are accompanied by the forming and breaking of bonds at sorption sites of water molecules. These processes may lead to some reorganization of the wood ultrastructure. The traditionally applied crystallographic descriptors, i.e. the mean microfibril angle and crystallinity, are unable to quantify such ultrastructural changes. The crystallographic texture analysis was performed to account for the reorganization of wood ultrastructure during the cyclic sorption. The Orientation Distribution Function (ODF) was separately calculated for the selected sorption cycles. Inverse pole figures, texture index, crystalline volume fraction, and integrated skeleton lines of the ODF made a set of crystallographic descriptors used to study the ultrastructural changes within this study. The registered reorganization of the ultrastructure was manifested in changes of the intensities of the individual texture components, including the disappearance of some components. However, the texture index, being the global measure of the crystallographic texture, was practically constant during the cycling sorption.