Browsing by Author "Brochier-Salon, M.C."
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- FTIR and NMR studies on lignin acetylationPublication . Cateto, Carolina; Barreiro, M.F.; Rodrigues, Alírio; Brochier-Salon, M.C.; Thielemans, Wim; Belgacem, Mohamed NaceurIn this work, a comparative study of an acetylation procedure, using four different lignin samples was performed. The chosen lignin samples, Indulin AT (Meadwestvaco), Alcell (Repap), Curan 27-11P (Borregaard LignoTech) and Sarkanda (Granit SA), represent both the guaiacyl and guaiacyl-syringyl type, and were obtained from different pulp processes (kraft and organosolv). Lignin was acetylated using an acetic anhydride-pyridine mixture and the final sample was recovered by precipitation. Final samples, with different reaction times (1 and 2 hours), were characterized by FTIR and 13C NMR analysis, and the obtained spectra were compared with the corresponding ones for non-acetylated samples. Within the used experimental conditions and samples, an incomplete acetylation yield appeared to be common. Total hydroxyl content, determined independently by titration and based on the 13C NMR results, was found to be in close agreement.
- FTIR and NMR studies on lignin acetylationPublication . Cateto, Carolina; Barreiro, M.F.; Rodrigues, Alírio; Brochier-Salon, M.C.; Thielemans, Wim; Belgacem, Mohamed NaceurIn this work, a comparative study of an acetylation procedure, using four different lignin samples was performed. The chosen lignin samples, Indulin AT (Meadwestvaco), Alcell (Repap), Curan 27-11P (Borregaard LignoTech) and Sarkanda (Granit SA), represent both the guaiacyl and guaiacyl-syringyl type, and were obtained from different pulp processes (kraft and organosolv). Lignin was acetylated using an acetic anhydride-pyridine mixture and the final sample was recovered by precipitation. Final samples, with different reaction times (1 and 2 hours), were characterized by FTIR and 13C NMR analysis, and the obtained spectra were compared with the corresponding ones for non-acetylated samples. Within the used experimental conditions and samples, an incomplete acetylation yield appeared to be common. Total hydroxyl content, determined independently by titration and based on the 13C NMR results, was found to be in close agreement.
- Lignins as macromonomers for polyurethane synthesis: a comparative study on hydroxyl groups determinationPublication . Cateto, Carolina; Barreiro, M.F.; Rodrigues, Alírio; Brochier-Salon, M.C.; Thielemans, Wim; Belgacem, Mohamed NaceurThe hydroxyl group contents of four technical lignins [Indulin AT (Meadwestvaco), Alcell (Repap), Curan 27-11P (Borregaard LignoTech), and Sarkanda (Granit SA)] were investigated in view of their valorization as polyols in polyurethane synthesis. The different hydroxyl group contents were determined by the following methods: titration and 1H-NMR, 13C-NMR, and 31P-NMR spectroscopy. The titration method chosen was on the basis of a standard method commonly used to characterize commercial polyols for polyurethanes synthesis. The values of the total and phenolic hydroxyl contents determined by the different techniques were found to be in good agreement. For the total hydroxyl contents, coefficients of variation of 5.6% (Alcell), 3.2% (Indulin AT), 2.3% (Sarkanda), and 6.2% (Curan 27-11P) were established. For the phenolic hydroxyl contents, a good correlation was observed between data obtained from 31P-NMR and 13C-NMR for all lignin samples, except for the Sarkanda lignin, for which a relatively high coefficient of variation (12.6%) was found. For softwood lignins (Indulin AT and Curan 27-11P), the phenolic hydroxyl content determined by 1H-NMR was always lower than that deduced from 31P-NMR and 13C-NMR spectroscopy.