Researchers and Industry Collaboration in the Development of Recycled Fibreboards
A visit to the SLU labs in Uppsala, Sweden
EcoReFibre unites many stakeholders and partners, working across different disciplines and sectors, all with a common goal to close the loop in the European fibreboards industry.
Project communication partners, the InnovaWood team, visited the sites to discover the science behind research: At the Swedish University of Agriculture Science (SLU), in cooperation with private companies, the recycled wood fibres are characterized and pressed into boards which then undergo mechanical and various other tests.
Collaboration between SLU and private companies centers around research and testing on mechanical and chemical properties of wood fibres and wood panels. On this occasion, under the guidance of Prof. Stergios Adamopoulos, ERF project coordinator, InnovaWood team discovered the work of Changling Xu and Dr. Percy Alao, who very generously showed us what a typical day at work looks like for them.
Changling Xu’s Research on Mechanical Properties of Recycled Fibreboards
Xu, currently a PhD candidate, is studying how much fibre content can be incorporated into a new MDF board without significantly affecting the material properties of the boards. He is analyzing both virgin and recycled fibres. Right now, the main focus is on post-consumer fibreboard (MDF), processing residues, and solid waste wood. As he explained, these are the three main sources for recovering fibres from recycled material.
Xu prepares mixtures of fibres, resin, glues, and other ingredients, experimenting with different ratios to create fibreboards. At the time of our visit, he was testing a mixture containing 25% recycled fibres and 10% resin for new MDF boards. His work can be divided into five stages.
Step 1: The Ingredients
Xu’s work begins with receiving various types of ingredients, provided by companies such as IHD and Dieffenbacher. Large storage barrels at the warehouse facilities hold fibres and resin.
Xu’s work begins with receiving various types of ingredients, provided by companies such as IHD and Dieffenbacher. Large storage barrels at the warehouse facilities hold fibres and resin.
Step 2: Fibre Preparation
The fibres are placed in large trays and positioned in an oven. To remove moisture, he sets the oven to 90°C. Then, glue and additives are added to the fibres in a blender (see picture below). Afterwards, the glued fibres are fluffed, ensuring they spread evenly within the panels.
Step 3: The Press
The prepared mixture is pressed into panels using a hot press. Currently, Xu is manufacturing 16mm-thick fibreboards.
Step 4: Conditioning
The fibreboards are cut into small samples and exposed to different environmental conditions, such as temperature and humidity (see picture below), to prepare them for mechanical testing.
Step 5: Mechanical Properties Testing
Fibreboards undergo various tests to measure their reaction to water and humidity absorption, as well as their stress resistance. The bending machine tests how much load a panel can withstand before breaking. Additionally, an X-ray scanner is used to measure the density of the boards. Typically, the density is higher on the surfaces and lower in the core. This density profile has a strong influence on the mechanical properties of the boards.
Dr. Alao’s research on fibre characterization and fibreboard structural analysis
Dr. Percy Alao, a post-doctoral fellow at SLU, focuses on the physical, chemical, and mechanical characterization of fibres. In particular, he conducts extensive particle size analysis to measure fibre length, aspect ratio, width, and other properties. This data is then used to compare how recycled fibres differ from virgin fibres.
Theoretically, virgin fibre length should be longer than that of recovered fibres. Percy Alao studies how variations in fibre size impact the final properties of fibreboards. The mechanical performance of the boards depends significantly on fibre length—if the fibres are too short, the boards become less stress-resistant and, as a result, less durable.
Dr. Alao also performs structural composition analysis using FTIR (Fourier Transform Infrared Spectroscopy) to assess the structural properties of post-consumer fibreboards. For example, this technique helps him quantify the resin content in these boards.
Some of the characterization work is not conducted directly at SLU but in collaboration with other project partners. Chemical characterization, such as measuring nitrogen content or formaldehyde emissions, is one such example.
What happens next with the data researchers generate?
Studying all of the properties mentioned above is critical for the project. The information received from these lab tests will be communicated to the industry partners of the project. Based on the results, the companies will prepare manufacture of MDF with recycled fibres on the industrial scale.
What is the importance of having such a project for society?
Both researchers agreed that closing the loop in the European fiberboard industry reduces wood waste and valorizes post-consumer materials by incorporating them into new panels. This is especially relevant now, with so many refurbishments happening, particularly in Europe, where buildings are being renovated or renewed to become more energy-efficient and passive.
When we recover materials from these buildings, instead of sending them to incineration, there’s a process to recycle and upscale them, giving the material new value. As global MDF production increases, this also helps ease the demand for new wood while reducing post-consumer wood waste—a win-win situation.
All these actions contribute to reducing the industry’s carbon emissions and positively impact the fight against climate change.
