Physico-chemical and structural characterization of alkali lignins from abaca fibre

Abaca fibre was treated with 1, 2.5, and 5% sodium hydroxide at 25, 35, and 50 degrees C for 0.5-5 h. The dissolved alkali lignins LA were separated from the solubilized polysaccharides using a two step precipitation method. The chemical and structural compositions of the pure lignin fractions LA we...

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Bibliographic Details
Published in:Journal of wood chemistry and technology 1998-01, Vol.18 (3), p.313-331
Main Authors: Sun, R.C, Fang, J.M, Goodwin, A, Lawther, J.M, Bolton, A.J
Format: Article
Language:English
Subjects:
alkali treatment
Applied sciences
characterization
chemical composition
Exact sciences and technology
lignin
Lignin and derivatives
Musa textilis
Natural polymers
phenolic compounds
Physicochemistry of polymers
plant fibers
ultraviolet spectroscopy
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Summary:Abaca fibre was treated with 1, 2.5, and 5% sodium hydroxide at 25, 35, and 50 degrees C for 0.5-5 h. The dissolved alkali lignins LA were separated from the solubilized polysaccharides using a two step precipitation method. The chemical and structural compositions of the pure lignin fractions LA were determined by UV, GPC, FT-IR, (13)C-NMR spectroscopy and nitrobenzene oxidation. All of the lignin fractions LA are free of associated polysaccharides. Their molecular-average weights ranged from 1960 to 2640. The results obtained by alkaline nitrobenzene oxidation showed that all the lignin fractions LA contain large amounts of non-condensed syringyl units, together with fewer non-condensed guaiacyl and p-hydroxyphenyl units. beta-O-4 and beta-5 ether bonds are found to be the major linkages between the lignin structural units. The less common beta-beta, beta-5, and 5-5' carbon-carbon linkages are also identified to be present between the lignin structural units. p-Coumaric acid and ferulic acid are linked to lignin molecules by ester and ether bonds, respectively.
ISSN:0277-3813
1532-2319
DOI:10.1080/02773819809349584