CHARACTERIZATION OF THE CHANGES OF COLOUR AND SOME WOOD COMPONENTS ON THE SURFACE OF STEAMED

The aim of this work was to explain the changes in the structure of the main wood components, which cause the colour changes on the surface of the steamed beech wood. The results obtained from the measurement of the surface colourity of the steamed beech wood showed that the steaming under the given conditions had influence on the change of the colourity what was reflected in the change of the total crystallinity index A1370/A2900 and another important ratios: A1332/A1316, A1370/ A1504 and A1736/ A1640. The obtained results showed that the steaming of beech wood resulted in the colour change of the surface, which was accompanied by the changes in the chemical characteristics of the main components of wood (cellulose, hemicelluloses and lignin). The colour changes of beech wood due to the steaming were the result of the complex chemical changes of the wood components. The steaming under the given conditions caused the partial degradation of hemicelluloses and amorphous cellulose regions and increase in the crystallinity of cellulose. It was accompanied with the concomitant release of lignincarbohydrate bonds in the surface layers of wood, which was reflected in subsequent removal of the easily degradable polysaccharides and in the relative increase of the lignin content.

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