Cellulose and water. They are the two basic ingredients in paper making. Water is added to the cellulose and then it is extracted again to produce paper sheets. Used paper can then be recycled into new paper by repeating the water process.
But here is a problem.
Each time the fibers in the cellulose are dried, they become a little stiffer and a little smaller. This process is called horning, and researchers at Karlstad University have now succeeded in reversing it – an important discovery because horning affects the paper’s properties.
– We want the paper fibers to behave like cooked spaghetti. They should be in one big tangle with many points where one fiber hits another fiber rather than like uncooked spaghetti where fiber only hits one or two other fibers. For each such hit point becomes a binding point and this makes the paper strong. The horning, which produces stiffer and stiffer fibers, makes this tangle worse and worse, and in the end it is no longer possible to make paper, says Björn Sjöstrand, docent in chemical engineering at Karlstad University.
Twice as much recycling
Typically, the fibers in paper can only go through this process a few times before they are used up. But with the new research, it will be possible to reuse the same paper significantly more times.
– We think at least twice as many times, but probably even more. We don’t have the exact numbers, but today they say somewhere between five and seven times, and we think many times more, says Björn Sjöstrand.
In the lab environment, they have already managed to figure out when and how the horning process takes place. Research is now continuing to try to understand why this process even takes place. But the findings can already be applied in real life.
Collaborates with paper mills
The research is done in collaboration with several paper mills and the next step for them is to prevent horning when they manufacture their paper. The problem is that this is done through new drying methods that are more energy-intensive than conventional methods.
According to Björn Sjöstrand, it is important to find a balance between increased recycling and the use of more energy. If more paper is to be recycled, it also becomes even more important that the paper in society is disposed of correctly from the very beginning.
– Now that we are starting to learn how to be able to recycle paper efficiently, it is very important that everyone helps each other so that we actually collect the material as well. That you do the right thing when you recycle, that newspapers go to newspapers and paper packaging goes to paper packaging. Usually that is the biggest difficulty in the whole recycling thing, says Björn Sjöstrand.