Elektronenbestrahlung von Faserstoffen: Auswirkungen auf Faser- und Papiereigenschaften

Pre-treatment of wood chips with electron irradiation results in significant changes of the mechanical pulp properties. Interesting conclusions for the application of such mechanical pulps can be drawn not only from the energy savings during refining (TMP), but also from the resulting pulp properties such as fibre morphology and drainability. The suitability for a partial application in newsprint has already been shown in mill-scale, and now, the property changes in the fibres are focused more in detail. Wood chips from spruce and aspen were irradiated for these trials. The varied morphology of mechanical pulps after raw material irradiation appears i.a. in shorter and more straight fibres with reduced cross-sectional dimensions and thus, with a lower coarseness. In the light microscope, smoother and more closed fibre surfaces could be observed. The swelling ability and the ability to bond water onto the fibre surface, respectively, that can be removed mechanically, decreased. Subsequently, a slight decrease of bonding ability was measured by tensile index. The development of strength and other handsheet properties are interpreted based on results from chemical analyses and extended microscopic tests and show significant differences for the investigated raw materials. Mechanical pulps after electron irradiation cannot only be produced more energy-efficiently, the deviated properties extend also their application possibilities. The presented results are gained in a joined project "ETMP" between Dresden University of Technology and VTT.