Publication YXY 2010
R. J. A. Gosselink, D. J. E. G. van, E. de Jong, E. L. Scott, J. P. M. Sanders, J. Li, G. Gellerstedt, Holzforschung 2010, 64, 193.
Functional properties of tech. lignins need to be characterized in more detail to become a higher added value renewable raw material for the chem. industry. The suitability of a lignin from different plants or trees obtained by different tech. processes can only be predicted for selected applications, such as binders, if reliable anal. data are available. In the present paper, structure dependent properties of four industrial lignins were analyzed before and after successive org. solvent extns. The lignins have been fractionated according to their molar mass by these solvents extns. Kraft and soda lignins were shown to have different molar mass distributions and chem. compns. Lignin carbohydrate complexes are most recalcitrant for extn. with org. solvents.
These poorly sol. complexes can consist of up to 34% of carbohydrates in soda lignins. Modeling by principle component anal. (PCA) was performed aiming at prediction of the application potential of different lignins for binder prodn. The lignins and their fractions could be classified in different clusters based on their properties, which are structure dependent. Kraft soft-wood lignins show the highest potential for plywood binder application followed by hardwood soda lignin and the fractions of Sarkanda grass soda lignin with medium molar mass. Expectedly, the softwood lignins contain the highest no. of reactive sites in ortho positions to the phenolic OH group. Moreover, these lignins have a low level of impurities and medium molar mass.