SOLID-STATE C-13 NUCLEAR-MAGNETIC-RESONANCE STUDIES OF WOOD DECAY .3. DECAY OF COLORADO BLUE SPRUCE AND PAPER BIRCH BY POSTIA-PLACENTA

C-13 cross-polarization magic-angle-spinning (CP-MAS) nuclear magnetic resonance (NMR) spectroscopy was used to study the residual wood material of spruce and birch after the wood was decayed by the brown-rot fungus, Postia placenta. The results showed that, when spruce was decayed by the brown-rot fungus, the carbohydrate components of wood were removed, and hemicelluloses were removed at a rate faster than cellulose. The cellulose which remained after the decay showed an increase in crystallinity. The aromatic region of the spruce C-13 CP-MAS spectra of spruce, attributed to lignin resonances, show that the lignin was altered during the decay process by a loss of methoxy groups. The lignin region of the C-13 CP-MAS spectra of decayed spruce indicate an increase in vanillic acid structures and alpha carbonyl moieties. The spectra of the decayed birch, in contrast to the spruch, indicate that the cleavage of lignin beta-0-4 linkages was the most prominent reaction occurring, rather than demethylation of the lignin.