The environmental concern on soil exploitation, linked to global warming by the Kyoto protocol, is responsible for increasing interest in the understanding of the role of the composition and structure of the soil organic matter (SOM) on soil carbon, C, dynamics. Thermal analysis and nuclear magnetic resonance (NMR) are applied to study the thermal properties, the structure and composition of the SOM of six samples with different C contents in order to improve the interpretation of results given by thermal analysis. Results showed that the direct integral of the combustion peaks obtained by DSC and the percentage of SOM given by TG were both directly related to the quantity of total soil C. Thus, soils with higher C content showed higher energy content too. The combustion temperatures of the curves given by DSC are those reported for labile OM. NMR results indicated the presence of aliphatic C, carbohydrates, and a weak signal in the aromatic C band in all the samples that was not detected in the DSC curves. Only two samples showed carboxyl/carbonyl C which was not detected by DSC also.
65.60 1.24 0.9965 415 288 6 1730 ν 2 (H 2 O) or C band (H 2 PO 4
hydroxyl (b) bands (ν 2 ) at 3668 cm −1 assigned to the out-of-phase vibration of the inner surface hydroxyls (c) bands (ν 3 ) at 3652 cm −1 attributed to the second out-of-phase vibration of the inner surface hydroxyls (d) bands (ν 5 ) at 3625 cm −1
CH/CH 2 /CH 3 group (2800–3100 cm −1 ), compounds containing carbonyl (1680–1800 cm −1 ), compounds containing aromatic ring (1300–1600 cm −1 ), aromatic ethers (asymmetric stretching of the C–O–C bands; 1042 cm −1 ) and CH 3 OH (671 cm −1 ), etc
Thermal degradation of lignin–phenol–formaldehyde and phenol–formaldehyde resol resins
Structural changes, thermal stability, and kinetics
decomposed into carbonyl groups (1650 cm −1 ) [ 9 ]. The broadness of this band is due to the overlap with the stretching aromatic C–C band (1600 cm −1 ). The peak at 1466 cm −1 , ascribed to the methylene bridges, disappeared when the temperature was
. Gauthier , MA , Stangel , I , Ellis , TH , Zhu , XX . A new method for quantifying the intensity of the C=C band of dimethacrylate dental monomers in their FTIR and Raman spectra . Biomaterials 2005 26 : 6440 – 6448 10.1016/j.biomaterials.2005