Wood modification with low molecular weight thermosetting resin is a frequently studied technique that is suitable for upscaling1–3. This treatment typically involves separate steps for impregnation, followed by drying, and then heat curing. The drying step aims at reducing the moisture content to minimise internal stresses that would otherwise occur in the heat curing stage. Heat curing takes place at elevated temperatures causing resin monomers to crosslink inside the wood cell wall4. Many studies in this field, including our previous publications, deal with small samples, where the drying stage is carried out in a conventional lab oven without causing drying failures5–8. Commercial wood modifiers, however, must invest in specialised equipment, using either a reactor with a closed system or a kiln with a superheated steam environment for drying and curing2,9,10. Our previous work has focused on the role of resin diffusion in the pre-cure drying stage11. By adjusting the relative humidity and temperature in the pre-cure drying step we could enhance the diffusion of resin molecules to the cell walls, which notably improved the dimensional stability. If this principle was better understood, it could help to further improve these modification systems. Therefore, we investigated the role of four different pre-cure drying regimes (air, vacuum, oven, kiln drying), and monitored the swelling coefficient after the treatment in different parts of the sample.
Keywords: wood modification, resin, wood drying, anti-swelling efficiency (ASE)
Authors
Carlo Kupfernagel
BioComposites Centre, Bangor University, Bangor, UK
Morwenna Spear
BioComposites Centre, Bangor University, Bangor, UK
Andrew Pitman
BM Trada, Buckinghamshire, UK
Graham Ormondroyd
BioComposites Centre, Bangor University, Bangor, UK
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