THE INFLUENCE OF CROSS-SECTION OF SPRUCE WOOD SPECIMENS ON SACCHARIDES CHANGES AT THERMAL LOADING

Spruce wood (Piceaabies L.) specimens with dimensions 60 x 60 x 800 mm (thickness x width x length) were thermally loaded by radiant heating. Tree different shapes of specimens were used; square, square with truncated edges and circular crosssections, respectively. The influence of cross-section on saccharides changes at thermal loading was investigated by high-performance liquid chromatography (HPLC). The results showed that hemicelluloses are less stable at thermal loading than cellulose. From non glucosidic units the content of mannose decrease in the maximum range, arabinose is the most stable saccharide. The smallest degradation of saccharides in square cross-section was observed; some minor amounts of hemicelluloses were found in charred layer. Larger changes were observed in square samples with truncated edges, followed by circular cross-sections samples. In charred layers of these samples the hemicelluloses were degraded completely.