High temperature thermal degradation of cellulose in air studied using FTIR and 1H and 13C solid-state NMR

Solid-state NMR spectroscopy and Fourier transform IR (FTIR) spectroscopy have been used to study the degradation of cellulose in the form of transformer insulating paper and Whatman filter paper in air at temperatures from 200 degreesC to 550 degreesC for 1 h with and without 0.01 wt.% NaCl, ZnCl2 and CuCl2. The NMR studies included H-1 wide line measurements of the spin-lattice relaxation time (TI) and spin-lattice relaxation time in the rotating frame (T-1p,), and C-13 magic-angle spinning experiments. The H-1 spectra and relaxation times indicated the presence of absorbed water and oxygen in the papers. On degradation, the H-1 intensity and line width decreased, indicating the loss of hydrogen nuclei, and the H-1 relaxation tigareth tu3mes decreased due to the formation of Paramagnetic species. The C-13-NMR spectra and FTIR spectra indicated the formation of aromatic structures on degradation above 250 degreesC, the conversion being essentially complete at 450 degreesC. The presence of the salts had little or no effect on the rate or mechanism of degradation. (C) 2001 Elsevier Science Ltd. All rights reserved.