In-situ penetration of ionic liquids during surface densification of Scots pine

Benedikt Neyses*, Kelly Peeters, Dietrich Buck, Lauri Rautkari, Dick Sandberg

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)
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The moisture-induced recovery of compressed wood is one of the major problems of wood densification technology. Achieving a cost-efficient surface densification process without the need for additional resins to eliminate the set-recovery may lead to an increase in value of low-density wood species. A previous study has shown that a pre-treatment with ionic liquids (ILs) can nearly eliminate the set-recovery. It was however observed that during the pre-treatment process the IL did not penetrate sufficiently deep into the wood to explain the achieved reduction in set-recovery. Based on these findings, the hypothesis was posed that further penetration of the IL into the wood occurs during the densification stage as a consequence of the applied heat and pressure. Thermo-gravimetric analysis (TGA) and gas-chromatography mass-selective-detection (GC-MSD) showed that the depth of penetration of the IL was greater after the densification process than before. Digital image correlation (DIC) showed that in regions with a high IL concentration, there was almost no set-recovery, and it gradually increased with a decrease in the IL concentration, as observed with TGA and GC-MSD analysis.

Original languageEnglish
Number of pages8
Publication statusE-pub ahead of print - 23 Oct 2020
MoE publication typeA1 Journal article-refereed


  • compressed wood
  • digital image correlation
  • set-recovery
  • spectroscopy
  • thermo-gravimetric analysis
  • wood modification


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