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ForestValue - Tree bark as a renewable source of wood protection materials for building applications

Alternative title: Bark som en fornybar kilde til trebeskyttelse

Awarded: NOK 2.2 mill.

The BarkBuild project tackles climate change by developing long-lasting wood building materials from bark-based chemicals and wood with low environmental impact. This will replace products having a larger carbon footprint and poor environmental soundness. It is the objective of this project to develop new bark-based wood protection and building formulations and demonstrate their technical performance, safety, and sustainability in wood impregnation, coating, and polymer composites in outdoor and indoor use. We will therefore assess the stability of different bark-based chemicals in wood impregnation and as a coating. The treatment of bulk wood with these chemicals needs to increase the resistance against wood degrading fungi and hopefully will improve other relevant wood properties as well. The application of these chemicals as a coating needs to prevent the underlying wood substrate from wetting and prevent the growth of surface fungi. Various Nordic wood species will be used for the treatment with bark-based chemicals. This also includes difficult-to-treat species, which will be pre-treated to increase uptake. Therefore, it is important to determine the uptake and distribution of different bark-based chemicals in wood and optimise the treatment accordingly. Ultimately, the material properties and its performance related to different use areas are important and will be analysed in the BarkBuild project.

Tree bark can be upgraded to wood treatment formulations that substitute harmful and petroleum-derived chemicals, and simultaneously extend functionality of wood in building and construction end-uses. Wood impregnation for outdoor building applications with bark-derived chemicals will cause permanent bulking, improvement in dimensional stability and changes in wood-water relations. A significant increase in durability against fungi is expected. We further expect that a lumen filling treatment, solely or in combination with the treatment on cell wall level, will increase the resistance against marine borers. In addition, the planned use of a diamine or polyamine cross-linkers will improve retention of the bark phenols and contribute to intumescent flame retardant properties. Wood coatings: Bark polyphenols can be used in combination with LCNF to prepare coatings that physically and chemically protect wood from fungal decay. Lignin has inherent antibacterial and antifouling properties, which can be used by itself or in combination with nanocellulose to create functional coatings for wood products. VOC absorbing composites for indoor applications: We hypothesise that bark-derived activated carbons allow for efficient deposition with metal oxides that can be incorporated into a coating system and used on indoor composite panels. The addition of the metal oxide on the activated carbon (MOAC) surface will boost generation of free radicals and response to visible light and result in enhanced VOC absorption in the developed coating system. Additionally, the activated carbon will enhance the fire and acoustic performance of the composite panels. Finally, valorisation of bark nanoparticles will improve the properties of bio-based polymer adhesives systems used within the composites.

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