Significant amounts of bark are potentially available from forest industry, with a total solid volume from sawmills corresponding to 149.000 tonnes and from pulp and paper industry corresponding to 504.075 tonnes in Norrbotten only. This huge amount of bark is currently used as fuel.
Spruce bark is composed of approx. 26% cellulose, 9% hemicellulose, 12% lignin and 32% extractives (tannins and stilbenes), and for pine bark 22%, 8%, 13% and 25% respectively. Tannins, which are polyphenolic compounds can be used to replace fossil-based phenol in many applications, such as insulating foams and adhesives. Taking into account the large quantities available, there is a great potential to exploit a hitherto untapped resource.
Biobased polymers have numerous applications and the potential to meet the natural and ‘‘green’’ demands of consumers. Continued research into maximizing the desired properties, optimization of the materials utilized, and processing methods is required to reduce costs and provide regulatory requirements of the material Bark extracts with specific properties (high tannin and high reactivity) are foreseen as starting material for formulation of different adhesives systems.
The main goal with the project is development of formaldehyde-free and water-resistant adhesives for plywood production based on domestic tannins extracts. Another foreseen innovation of the project is the formulation of a domestic tannins/lignin-based adhesives combined with a cellulose nanofibrils as filler. Hence, the suggested project, covering the main actors along the value-chain, has a very good potential to explore the use of bark as a sustainable and valuable feedstock that can strengthen the Swedish bioeconomy.