Impact of a conditioning step during the treatment of wood with melamine-formaldehyde resin on dimensional stabilisation

Md Tipu Sultan, Daniela Altgen, Muhammad Awais, Lauri Rautkari, Michael Altgen*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

Abstract

The dimensional stabilisation of wood using thermosetting resins relies on the resin uptake into the cell walls. This study tested if a conditioning step after the impregnation and before the final heat-curing enhances the cell wall uptake to improve dimensional stabilisation without increasing the chemical consumption. Small blocks of Scots pine sapwood were vacuum-impregnated with an aqueous melamine formaldehyde solution and conditioned at 33, 70, or 95 % RH for up to 1 week before drying and curing the blocks at 103 °C. However, the conditioning step decreased the cell wall bulking and the moisture exclusion effect compared to the immediate heat curing of the impregnated samples. Analyses of the resin-treated samples by scanning electron microscopy, IR spectroscopy and confocal Raman microspectroscopy provided evidence of wood hydrolysis and polycondensation of the resin within the cell lumen during the conditioning step. Hydrolysis and removal of wood constituents may have counterbalanced the cell wall bulking of the resin. Polycondensation of the resin in the lumen increased its molecule size, which could have hindered the cell wall diffusion of the resin.

Original languageEnglish
Pages (from-to)37-46
Number of pages10
JournalHolzforschung
Volume78
Issue number1
Early online date24 Nov 2023
DOIs
Publication statusPublished - 1 Jan 2024
MoE publication typeA1 Journal article-refereed

Keywords

  • thermosetting resin
  • vibrational spectroscopy
  • water vapour sorption
  • wood modification

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