Role of intrinsic and extrinsic xylan in softwood kraft pulp fiber networks

Jana B. Schaubeder, Stefan Spirk, Lukas Fliri, Eliott Orzan, Veronika Biegler, Chonnipa Palasingh, Julian Selinger, Adelheid Bakhshi, Wolfgang Bauer, Ulrich Hirn*, Tiina Nypelö*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

Xylan is primarily found in the secondary cell wall of plants providing strength and integrity. To take advantage of the reinforcing effect of xylan in papermaking, it is crucial to understand its role in pulp fibers, as it undergoes substantial changes during pulping. However, the contributions of xylan that is added afterwards (extrinsic) and xylan present after pulping (intrinsic) remain largely unexplored. Here, we partially degraded xylan from refined bleached softwood kraft pulp (BSKP) and adsorbed xylan onto BSKP. Enzymatic degradation of 1 % xylan resulted in an open hand sheet structure, while adsorption of 3 % xylan created a denser fiber network. The mechanical properties improved with adsorbed xylan, but decreased more significantly after enzymatic treatment. We propose that the enhancement in mechanical properties by adsorbed extrinsic xylan is due to increased fiber-fiber bonds and sheet density, while the deterioration in mechanical properties of the enzyme treated pulp is caused by the opposite effect. These findings suggest that xylan is decisive for fiber network strength. However, intrinsic xylan is more critical, and the same properties cannot be achieved by readsorbing xylan onto the fibers. Therefore, pulping parameters should be selected to preserve intrinsic xylan within the fibers to maintain paper strength.

Original languageEnglish
Article number121371
Number of pages10
JournalCarbohydrate Polymers
Volume323
Early online date18 Sept 2023
DOIs
Publication statusPublished - 1 Jan 2024
MoE publication typeA1 Journal article-refereed

Keywords

  • Adsorption
  • Bleached softwood kraft pulp
  • Enzymatic degradation
  • Hemicelluloses
  • Mechanical properties
  • Paper

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