SURFACE CHARACTERIZATION OF UNBLEACHED KRAFT PULPS BY ENZYMATIC PEELING AND ESCA

Specific enzymes hydrolyzing pulp carbohydrates can be used for charac terization of pulp fibres. By combining enzymatic peeling of fibre hem icelluloses with novel techniques of surface analysis, such as ESCA, n ew information can be obtained on the location of different components , i.e. xylan, glucomannan and lignin on the fibre surfaces. In this wo rk unbleached kraft pulps were selectively peeled with purified Tricho derma reesei xylanase and mannanase and the structural modifications c aused by the removal of the hemicelluloses were analyzed with ESCA. Th e removal of the accessible portion of the pine kraft xylan increased the amount of surface lignin, whereas mannan removal had no effect on the amount of lignin on the surface. In the case of birch kraft pulp t he removal of accessible xylan did not enhance the amount of lignin on the surface. However, in birch kraft pulp the removal of xylan decrea sed the amount of extractives covering the surface.