application of atr infrared spectroscopy in wood acetylation

acetylation is a chemical modification of wood to enhance its properties. ir-spectroscopy is a useful technique for proofing chemical bondings in wood and the at-tenuated total reflection (atr) infrared spectroscopy technique was applied as an eas-ier technique over other ir-spectroscopies. in this research, different degrees of acetyla-tion, weight percentage gains (wpgs) in beech and pine mini-stakes were achieved by us-ing acetic anhydride. acetylated samples were analyzed by applying an attenuated total reflection (atr) infrared spectroscopy technique. comparison of the acetylated samples with non-acetylated woods showed that hydroxyl groups (o-h) were diminished at wave numbers of about 3,354-3,328 cm-1 due to the substitution of hydrophobic acetyl groups in cell wall polymers. a strong peak appeared at wave numbers of about 1,733-1,728 cm-1 in beech and 1,737-1,728 cm-1 in pine due to the carbonyl (c=o) stretching of acetyl groups. the magnitude of the bands increased with raising the weight percentage gains (wpgs). the methyl deformation of the acetyl groups induced at wave number 1369 cm-1 caused by the stretching of c-h in polysaccharides. there was also a clear increase in the magni-tude of the wave numbers at about 1234-1226 cm-1 in beech and 1236-1226 cm-1 in pine due to the stretching of c-o and carbonyl deformation in the ester bonds during the ace-tylation of lignin.