INFLUENCE OF FIRE ON SPRUCE WOOD LIGNIN CHANGES

The paper deals with the chemical and physico-chemical changes of lignin during the degradation of spruce wood by one-sided thermal loading according to the standard temperature curve ETK in temperature range from 30 degrees C to 310 degrees C. The changes caused by thermal loading were studied with infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC) and nitrobenzene oxidation (NBO). We observed the lignin and extractives amount increase at thermal loading. The changes of functional groups took place in lignin - amount of alpha-C=O and -OCH3 decreased, amount of beta-C=O increased. At lower temperatures of the thermal treatment, the lignin macromolecule is degraded, the relative molecular weights decrease, at higher temperatures the condensation reactions arc predominant and the relative molecular weights increase.