| Autor: |
J.J.M. Sleeckx, J.W. de Leeuw, J.C.M. Sprenkels, M. De Pooter, J.P.T. Jensen, Margriet Nip, P.J. Holloway |
| Rok vydání: |
1987 |
| Předmět: |
|
| Zdroj: |
Journal of Analytical and Applied Pyrolysis. 11:287-295 |
| ISSN: |
0165-2370 |
| DOI: |
10.1016/0165-2370(87)85036-2 |
| Popis: |
Recently we described the occurrence of a highly aliphatic and resistant biopolymer in leaf cuticles of some modern and fossil higher plants. The highly aliphatic nature of this biopolymer was deduced from flash pyrolysis-gas chromatographic and flash pyrolysis-gas chromatographic-mass spectrometric data. In an attempt to further identify its molecular structure, a “purified” fraction of the biopolymer was subjected to solid state 13 C NMR and IR spectroscopy, differential scanning calorimetry and elemental analysis. Surprisingly the 13 C NMR data indicated that ca. 50% of the sample consists of carbohydrate moieties and that the remainder can be ascribed to the expected polyethylene moieties. The IR and differential scanning calorimetry data were in accordance with these 13 C NMR data as well as the elemental analysis. The cross-polarization behaviour during the 13 C NMR experiments and the percentage of crystallinity in both the polyethylene and the saccharide moiety (ca. 50%) are indicative of covalent bonds between the two. This was further supported by additional density scanning calorimetric and flash pyrolysis-gas chromatographic analyses. Obviously analysis of the aliphatic biopolymer by flash pyrolysis alone was highly misleading since the pyrolysate only reflected a limited and specific part of the macromolecular structure. This investigation very clearly demonstrates that analytical pyrolysis should be used only in combination with other analytical methods, especially solid state 13 C NMR and IR spectroscopy, to elucidate the molecular substructures of insoluble macromolecular or polymeric compounds. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
