Abstract:

Milled wood lignins(MWL)is isolated from Chinese fir and poplar"Sanbei"No.1 wood.The lignins are characterized on the basis of FTIR,UV,HPLC,¹HNMR spectroscopy and elemental analyses. The results show that:(1)The carbon content in Chinese fir lignin is 1.23%higher than that in poplar "Sanbei"No.1 lignin,but the hydrogen and oxygen contents are respectively 0.22%and 0.85%lower than those in poplar"Sanbei"No.1 lignin.(2)The empirical formulas of C₉ are calculated for Chinese fir lignin and poplar"Sanbei"No.1 lignin as C₉H_8.08O_2.46(OCH₃)_0.94 and C₉H_7.86O_2.33(OCH₃)_1.41,respec-tively based on their nlethoxyl contents and elemental composition.(3)The OH_aliph is 78.8%in total numbets of hydroxyl groups of Chinese fir lignin,and the OH_ph is 21.2%.The OH_aliph is 67.5%and the OH_ph is 32.5%in the poplar"Sanbei"No.1,lignin.(4)The IR spectra of Chinese fir lignin shows the typicalsoftwood characteristics,but the poplar"Sanbei"No.1 is not absolutely coincident with the IR spectra characteristics for the temperate hardwoods.(5)The per-C₉-unit average proton numbers of β—O—4 structures in Chinese fir lignin and poplar"Sanbei"No.1 lignin are 0.33 and 0.50,the β-5 structures are 0.23 and 0.16,and the β-β structures are 0.92 and 0.67 respectively.

Key words: Chinese fir MWL, Poplar "Sanbei" No.1 MWL, Chemical structure characteristics