The aim of this study was to investigate if added beech xylan with low molecule
weight (Mw) could penetrate into the fiber wall to a greater extent compared to
xylan with high Mw. The high Mw (ca 11000) xylan was degraded using enzymes
to obtain xylan with low Mw (ca 1800). The influence from the added xylan on the
strength properties was evaluated. The cooks in this study were performed without
mechanical damage introduced during the cooking process, thus any conclusions
of the impact from adding low Mw xylan on the sensitivity towards mechanical
damage was not possible.
The different microscopy analyses performed could not show any evidence for a
higher penetration of xylan into the fiber wall when producing the pulp with
addition of low molecular weight (low Mw) xylan.
The low Mw xylan did not contribute to any improved pulp properties, rather the
opposite. Addition of low Mw-xylan did not result in straighter fibers compared to
the Ref-pulp, which was the case for the high Mw-xylan-pulp. The tensile indexdevelopment
(tensile vs PFI-beating and tensile vs density) for the low Mw-pulp
was even worse compared to the Ref-pulp. The pulp produced with addition of the
high Mw-xylan showed, as earlier seen, an improved tensile index development
compared to the Ref-pul
