Eigenschaften von Zellstoffen aus Holz von Pappeln unterschiedlicher Klone, Standorte und Baumalter
Properties of pulps prepared from poplar wood of different clones, sites and ages
On poplar wood, the influence of some different growth factors such as clone type (Muhle-Larsen, Oxford, Androscoggin), age (14 to 21 years) and site (high and poor fertility) on various anatomical properties such as fibre length, reaction wood, and the ratio of sap- to heartwood as well as on chemical properties (lignin and extractive content, pH value, and buffering capacity) was determined. The results reveal that the clone, site and age have a significant influence on the fibre length, reaction wood content and the build up of heart wood. On sites of poor fertility young poplar wood has a high heart wood content, whereas old poplar trees show a higher heart wood content on sites of high fertility. Fibre length and reaction wood content were higher on sites of high fertility. Moreover, the physical-technological properties of pulps prepared from the different clones according to the NSSC-process and the sulfate method were evaluated. The results show that, within the age investigate d, the site is much more important than the age of the tree: NSSC-pulps from poplar raised on sites of high fertility show higher yield and much better mechanical properties and whiteness compared to those raised on sites of poor fertility. This may be due to higher sapwood ratio and consequently longer fibre length. Sulfate pulps from poplar wood of different sites showed only insignificant differences in their mechanical properties.