Abstract

In Scandinavian thermo-mechanical pulp (TMP) is made primarily of Norway spruce wood. During recent years there has been an increasing interest in making TMP pulp of Scots pine. TMP of pine is known to demand more electrical power during refining to pulp to a specific sheet density compared to spruce. The fundamental reason behind this difference is however not completely understood. A large trial was set up together with industry within the frame of the Wood Ultrastructure Research Centre (WURC) to try to understand this difference in behavior from a morphological and ultrastructural perspective. In this work the morphology of fiber populations of Norway spruce and Scots pine originated from 8 sample trees were studied and compared. Results revealed morphological differences regarding fibre distribution, shape, amount of latewood/earlywood, and annual ring width within and along the stem. A great portion of pine latewood fibres has much thicker cell walls and much narrower cell lumens than the corresponding fibres in spruce. It was also observed that pine latewood fibres become thick walled much earlier during the growth season than the corresponding fibres in spruce. This is also shown to have an impact on the collapse resistance (CR) of these fibres. Calculations of CR show that pine latewood fibres could be more difficult to collapse. This is probably further enhanced by fibre geometry and cell wall ultrastructure. A few very stiff and collapse resistant fibres may influence pulp properties, like freeness, by preventing the proper formation of the paper sheet. These fibres in pine may be one of the causes for higher energy consumption to a specific density compare to spruce pulp

Published in

Conference

COST Action E50 Workshop: Characterisation and application of cell wall macromolecules

SLU Authors

• Bardage, Stig

  • Department of Forest Products, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Forest Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/21203