INFRARED SPECTROSCOPIC CHARACTERISTICS OF BAGASSE CRESOL LIGNIN

The IR spectra from 200 to 4000 cm(-1) of the precipitated bagasse lig nin from waste black cresol pulping liquor obtained at various tempera tures (160-190 degrees C) after 1.5 h and after various pulping times (3/4-3 h) at 170 degrees C were studied. The precipitated bagasse lign in from kraft pulping liquor obtained at 170 degrees C after 1.5 h was also used for comparison. It was found that the band intensities of t he phenolic hydroxyl group and the carbonyl group of precipitated lign ins increased, whereas the intensity of the methoxyl group decreased w ith increasing time and temperature of pulping. The absorbances of the hydroxyl, methoxyl and carbonyl groups relative to the aromatic ring band vibration at 1505 cm(-1) were correlated to provide more informat ion on the effect of these pulping parameters on the molecular structu res changes in cresol lignin.