CHARACTERISTICS OF MILLED WOOD LIGNINS ISOLATED FROM DIFFERENT AGES OF NALITA WOOD (Trema orientalis)

摘要

Milled wood lignins from four different ages of nalita and aspen wood were isolated and characterized by UV,FT-IR,1H and 13C NMR.spectroscopy.Elemental composition,methoxyl analysis,molecular weight and alkaline nitrobenzene oxidation of the isolated lignin have been also studied.The C9 formula for 30 month-old nalita was C9H9.11O3.94(OCH3)1.36,while that of aspen was C9H8.93O3.50(OCH3)1.52.The alkaline nitrobenzene oxidation products showed a syringyl to guaiacyl ratio of nalita and aspen lignin of 1.6-1.8 and 3.0,respectively.The weight average molecular weight of nalita lignin was higher than that of aspen lignin. The polydispersity of nalita lignin decreased with tree age.1H NMR study of nalita MWL showed that the beta- O-4 structural linkage increases with tree age.Nalita and aspen MWLs contained both erythro and threo configuration,although the erythro proton evidences a stronger peak.