Principal component analysis of the hydroxymethylation of sugarcane lignin:: A time-depending study by FTIR

The hydroxymethylation of Acetosolv lignin from sugarcane bagasse was studied at 40 degrees C between 0.25 and 8 h by Fourier-transformed infrared spectroscopy (FTIR). Principal Component Analysis (PCA) of the spectra has determined that addition of formaldehyde to the lignin fragments was completed within 4 h. After that time, only condensation of the fragments occurs, leading to a resol-type crosslinked resin. PCA performed in selected regions of the FTIR spectra showed that the same results are also obtained for the stretching region of O-H and C-H within the range from 2800 to 3800 cm(-1), which is not usually considered in the spectroscopic evaluations of modified lignins.