X-ray scattering and microtomography study on the structural changes of never-dried silver birch, European aspen and hybrid aspen during drying

Kirsi Leppänen*, Ingela Bjurhager, Marko Peura, Aki Kallonen, Jussi-Petteri Suuronen, Paavo Penttilä, Jonathan Love, Kurt Fagerstedt, Ritva Serimaa

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

37 Citations (Scopus)

Abstract

The impact of drying on the structure of the never-dried hardwood cell wall was studied at nanometer level by means of wide-and small-angle X-ray scattering (WAXS, SAXS), and at micrometer level by X-ray microtomography (μCT). Never-dried silver birch, European aspen and hybrid aspen samples were measured by WAXS in situ during drying in air. The samples included juvenile and mature wood, as well as normal and tension wood to allow comparison of the effects of different matrix compositions and microfibril angles. The deformations of cellulose crystallites and amorphous components of the cell wall were detected as changes in the cellulose reflections 200 and 004 and amorphous halo in the WAXS patterns. Especially, the width of the reflection 004, corresponding to the cellulose chain direction, increased due to drying in all the samples, indicating an increase of strain and disorder of the chains. Also, the cellulose unit cell shrank 0.2-0.3% during drying in this direction in all the samples except in hybrid aspen tension wood. According to the SAXS results of silver birch, the distance between micro-fibrils decreased during drying. It was detected by μCT that the mean cross-sectional maximum width of the parenchymatous rays decreased from that of never-dried to air-dried birch by roughly 16%.

Original languageEnglish
Pages (from-to)865-873
Number of pages9
JournalHolzforschung
Volume65
Issue number6
Early online date8 Jul 2011
DOIs
Publication statusPublished - 1 Oct 2011
MoE publication typeA1 Journal article-refereed

Keywords

  • cellulose crystallite
  • drying
  • European aspen
  • hybrid aspen
  • silver birch
  • WAXS
  • X-ray microtomography

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