Lignin structure and wood properties

摘要

The objective of this study was to understand the relationship between lignin structural organization and certain wood properties. Lignin, which constitutes 20-30% of the weight of all woody plants, functions as a binding and encrusting material inthe cell wall, giving rigidity to the overall plant structure. More than 60% of all linkages in lignins isolated (Bjorkman) from Aspidosperma macrocarpum [A. macrocarpon], Lophanthera lactescens, Gallesia gorazema, Peltogyne paniculata, and Aspidospermapolyneuron were of the beta-O-4 alkyl aryl ether type. This unit plays an important role in the physical and mechanical properties of wood. Percentages of beta-O-4 unit were estimated by infrared spectroscopy. An Index of Molecular Flexibility (IMF) wasintroduced in order to hypothetically estimate the contribution of this unit toward wood flexibility, (under the assumption that the beta-O-4 linkage is positively correlated with flexibility). Lignins from Aspidosperma macrocarpum (AM) and Aspidospermapolyneuron (AP) show the highest and lowest structural complexity (diversity of linkage types beta-beta, beta-5, beta-O-4, etc.) with IMF values of 2.02 and 3.00, respectively. In this case, lignins AM and AP are supposedly contributing toward lowest andhighest grade of wood flexibility, respectively, which demonstrates the hypothesis that beta-O-4 linkages correlate well with flexibility.