The project ran between May 2023 and October 2023.
The project developed knowledge on the modification of Scots pine sapwood with a 100% biobased formula. Tannin-based formulas were prepared with different concentration ranges of a biobased crosslinker, i.e., below 10%, below 20% and above 20%, to modify Scots pine (Pinus sylvestris L.) sapwood. The Scots pine heartwood was used as the reference sample. The performance of modified wood was evaluated in terms of weight percentage gain (WPG), bulking coefficient (BC), leaching resistance, dimensional stability in terms of anti-swelling efficiency (ASE), accelerated weathering and resistance against mold and decay fungi. The experimental results showed that a high WPG was attained (44%) with a crosslinker concentration of below 20%. However, improved BC, leaching resistance and ASE were observed in modified wood with a crosslinker concentration of above 20%. After accelerated weathering, this group of treated samples showed lower surface cracks. The durability against mold was only improved at high concentrations of the crosslinker, and there was no effect mold infestation compared to heartwood and control sapwood. However, the durability against decay fungi were strongly improved by modification. Maximum penetration results showed that larger samples were not fully impregnated, and thus adjustment of impregnation parameters could increase the WPG and thus improve the durability further. The overall results indicated the potential for modification of Scots pine sapwood with tannin-based formulas, while there are still some challenges that exist in the lab scale, specifically high leaching of tannin solution. This, therefore, creates new research questions to be answered in the future before moving to the industrial scale.
Picture from the project.
Participants
Linnaeus University and Stora Enso.
Budget
The project’s total budget was 1 MSEK.