EVALUATION OF THE STRUCTURE AND ACID-BASE PROPERTIES OF BULK WOOD BY FT-RAMAN SPECTROSCOPY

The structure of pine wood (Pinus silvestris L.) has been analyzed by FT-Raman spectroscopy, taking birch wood and the wood components cellu lose, hemicellulose (xylan), and lignin as well as previously characte rized wood resins as references. The acid-base properties of hulk pine wood were evaluated by comparing the spectra recorded before and afte r the treatment with various solvents. After the treatment with the pr obe liquids having only a Lifshitz-van der Waals (LW) component, it wa s found that the LW interactions in pine wood take place without chang ing the main structure. After treatment with Lewis acid-base active pr obe liquids, the spectra indicate that, e.g., the intense peak located at similar to 2936 cm(-1) (CH2 stretch) seems to disappear, suggestin g that this peak may be related to Lewis acidity. In addition, after t reatment with a Lewis acid, it was found that the intense peak located at similar to 1657 cm(-1) (C=C) is shifted, relating to Lewis basicit y. With the ratio similar to 2936/ similar to 1657 cm(-1) as a measure of the acid-base properties of bulk wood, a value of about 2.00 indic ates that the bulk pine wood is largely acidic. The pH determined supp orts the evaluation made by FT-Raman spectroscopy, (C) 1998 Academic P ress.