The lignin of the diffuse porous angiosperm tree Triplochyton scleroxylon K. Schum with low syringyl content
1994
Faix, O. | Stevanovic-Janezic, T. | Lundquist, K.
"Milled wood lignin" was isolated from Triplochyton scleroxylon tree (wawa MWL) and subjected to elemental analysis before and after acid treatment, and to analytical pyrolysis. Both FT-IR and 1H NMR spectra were recorded. For comparison, lignins from spruce and beech isolated by the MWL, dioxane/HCl (DIL), and Cuene (CUL) techniques were also characterized. The residual carbohydrate content of the lignins was estimated. Wawa MWL is a GS lignin with 88% G and 12% S content. The utility of analytical pyrolysis and FT-IR for lignin classification is discussed. FT-IR spectroscopy, calibrated with data of 50 MWLs (PLS approach), gives reliable results with a minimum of experimental work. The yields of S phenols obtained by pyrolysis has to be multiplied with a factor around 0.5 for correction if the S content of a lignin is low. The cross-linking indices and OHphen/OHaliph ratios of lignins increase in the order MWL < DIL < CUL. 1H NMR spectroscopy is also helpful to recognize the S/G ratio of a lignin.
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