Permalink : http://hdl.handle.net/2115/38225

KEYWORDS : Heat treatment;Japanese cedar;Lignin;Raman spectroscopy;Softening

Raman spectra of Japanese cedar (Cryptomeria japonica) sapwood and heartwood heated at low temperatures (50-160℃) were recorded, and spectral changes of Raman bands due to heat treatment were analyzed through a difference spectrum method. Although the heat treatment intensified fluorescence emitted from heartwood much more strongly than that from sapwood, there was no significant difference in vibrational Raman band contours between sapwood and heartwood. The Raman spectral changes associated with heat treatment of Japanese cedar were quite similar to those of Japanese larch (Larix leptolepis). The most characteristic and important spectral change was a decrease in intensity of the Raman band at 1655 cm^[-1], which can be attributed mainly to stretching vibrations of C=C and C=O groups in lignin molecules. The intensity at 1655 cm^[-1] decreased with increasing heat-treatment temperature and time, and the decrease rate had a strong dependence on water content.