Mechanical and morphological bond line properties of silver birch wood pretreated by aqueous extraction

Max Engelhardt, Thomas Böger, Michael Gigl, Chen Meng, Klaus Richter, Antoni Sánchez-Ferrer

Research output: Contribution to journalArticlepeer-review


While bonding for structural applications in Europe was limited to only a few softwood species in the past, forest alterations toward more climate stability will increase the diversity of tree species. This requires an understanding of typal wood-adhesive interactions. To help facilitate birch wood bonding, its cold-water soluble extractives and their effects on mechanical performance and bond line morphology were studied using water-borne melamine-urea-formaldehyde (MUF) and hydrophobic solvent-free polyurethane (PUR) adhesives. Extractives classes were identified via mass spectrometry and their concentration and extraction kinetics were evaluated. The analysis revealed that the mechanical properties of the bond line were essentially unaffected by extraction when using the hydrophobic PUR adhesive. Increased degrees of extraction resulted in reduced MUF penetration, and slightly thicker bond lines, however, the mechanical results indicate improved performance, indicating fewer defects in the cured adhesive network.

Original languageEnglish
Pages (from-to)114-132
Number of pages19
JournalJournal of Wood Chemistry and Technology
Issue number2
StatePublished - 2024


  • Birch wood
  • bond line
  • extractives diffusion
  • microscopy
  • tensile shear


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