Multifunctional eco-friendly building board - alternative use of sawmill sawdust
At present, the Swedish sawmill industry produces nearly 20 million m3 of sawn timber annually, resulting in about 2 million m3 of sawdust, which is mainly used for heating the sawmill's dryers or homes, etc. Today, there is no economically realistic alternative use for the sawdust other than for energy purposes, while the volume of bark separated at the sawmills is generally sufficient for the sawmills' heating needs.
Using the sawdust as fuel results in negative consequences:
- High quality raw material is used as fuel.
- A decrease in the value of the raw material from approx. 500 kr/m3 (saw timber) to 150 kr/m3 or 170 kr/MWh (sawdust) despite having passed a processing stage.
- Extremely short life cycle for sawdust (days):
The CO2 storage effect of wood is lost for about 10-12% of the timber volume, which can be used to criticize the Swedish forest industry from an environmental perspective.
At the same time, the construction industry is seeking environmentally better alternatives to today's fossil-based (gypsum) and glue-based board materials (chipboard, OSB, plywood).
Ionic liquids are environmentally friendly salts that are liquid below 100C and are among the "green chemicals" that are now increasingly used in the manufacture of wood fiber-based products. Preliminary experiments show that some ionic liquids can be used to bind wood particles, while having properties that can give the wood material improved fire resistance, less moisture absorption and better dimensional stability.
Studies within the current project show that although ionic liquids can be used to bond chipboard, they are not as effective as conventional adhesives, regardless of pressing times, temperatures or the percentage of ionic liquid added. In addition, conventional European suppliers of ionic liquids are prohibitively expensive, although significantly cheaper suppliers may be available in, for example, China.
In an effort to determine alternative systems similar to ionic liquids, imidazole has shown very promising results in producing wood-based board materials that were extremely moisture stable. An ongoing continuation project is now focusing on imidazole as a binder for chipboard, and preliminary results indicate that classification according to the European standard EN312 will be met.
Field: Materials and processes
Budget: 191,000 SEK
Schedule: April 2022 - December2022
Project leader: Dennis Jones, Luleå University of Technology
Funding: This project is funded by TCN.
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