How can forest-based materials be made stronger, more functional and at the same time contribute to a more sustainable industry? This is a question being explored by doctoral researcher Morassa Raouf.
Cellulose nanofibrils (CNF) and microfibrillated cellulose (MFC) are renewable materials with a large surface area and an excellent ability to form dense networks. They have the potential to be used in applications ranging from paper reinforcement and packaging coatings to future membrane technologies. One challenge, however, is that their production requires energy-intensive fibrillation and that the materials are difficult to dewater once they have been finely dispersed.
In her research, Morassa Raouf has investigated a method in which pulp is first treated using Fenton oxidation and then mechanically processed. The chemical treatment alters the cellulose fibres, making them easier to separate into very fine fibrils. The results show that the pre-treated pulp forms a significantly denser fibril network than material processed solely by mechanical means.
“The project demonstrates how the choice of chemical treatment and processing conditions affects cellulose from production through to final performance. This knowledge is important for the development of bio-based materials that combine high performance with industrial applicability,” says Morassa Raouf.
She has also examined how the material performs as a coating for paper. As the amount of CNF/MFC increased, the paper’s ability to prevent air from passing through the material improved, an important property in many packaging applications. At the same time, water absorption and surface characteristics were affected in different ways depending on the thickness of the coating.
In another part of the project, CNF/MFC was blended with conventional hardwood pulp. Tests showed that the materials produced stronger paper sheets by creating denser bonding between fibres. However, the increased degree of fibrillation also had a drawback: the materials retained more water and became considerably more difficult to dewater during manufacturing.
The findings therefore highlight a key trade-off for the fibre-based materials of the future. The properties that provide greater strength and improved barrier performance can simultaneously make the production process more challenging.
