Die Verbesserung der Impraegnierbarkeit von Fichtenholz mittels chemischer und enzymatischer Vorbehandlung

Finely ground spruce ( Picea abies (L.) Karst. ) was incubated with different enzyme preparations. The enzyme concentration, incubation time, temperature and buffer concentration were varied. The nature and quantity of uronic acids and neutral sugars released from the cell walls were determined. The most effective enzyme preparations were shown to be those with a broad cellulolytic and hemicellulolytic spectrum of activity. Specific pectinases were found not to be particularly effective. Sapwood and heartwood were broken down in equal degrees. Enzymatic preliminary treatment of intact spruce improved the permeability of the timber. The extent of the improvement was dependent on the enzyme preparation applied, the enzyme concentration, the incubation time, the incubation temperature and the origin of the timber. Enzymatic preliminary treatment was more effective in sapwood than in heartwood. Scanning electron microscopy made it possible to demonstrate the decomposition of the torus and the margo of the bordered pits as well as the decomposition of the pits between tracheids and parenchyma. The compression strength and the modulus of elasticity were not reduced. Preliminary treatment of intact spruce with alkali, acids and chelating agents did not result in improved permeability.