One of the consequences of the communication digitalization is that less paper is used for printing and writing. In parallel, new uses for cellulose are being investigated, which, as nanofibers, is a promising reinforcing additive from different materials.
Cellulose nanofibers, NFC, are tiny cellulose fibers with a large specific surface area and high mechanical strength. Their high interaction capacity with larger fibers make them an extraordinarily lightweight and strong reinforcing material.
NFCs have become a powerful industrial additive with a wide range of uses and applications of renewable and biodegradable characteristics, since they are obtained from mechanical disintegration and/or chemical treatments of plant fibers. By adding them to different materials, the strength properties of the resulting composite, without significantly increasing its mass, can be improved.
“NFCs consist of thousands of glucose units. Each has three hydroxyl groups, which tend to attract each other, hindering their dispersibility in liquids. In addition, due to their high polarity, NFCs can only be used in hydrophilic media. Different investigations have proposed strategies to modify these properties including acetylation, through which hydroxyl groups are substituted by acetyl groups” explains Dr. Gustavo Cabrera, researcher in the UDT Biomaterials Department and Project Director of the work entitled “Development of chemically modified cellulose nanofiber (NFC) production technology for applications with high economic interest and global impact”, CORFO initiative, High Technology Innova Program 19IAT-112022.
Applications in adhesives and bioplastics
Urea formaldehyde adhesives are used massively in the production of chipboards and MDF. Although they constitute only 10% of their mass, these adhesives represent 30 to 35% of the total cost of the panels. In addition, formaldehyde is a carcinogenic compound for humans, so products that replace it are being sought globally.
In that line, UDT produced acetylated NFCs on a laboratory scale and proved their high compatibility with different types of resins, including adhesives of the urea-formaldehyde type. Through a project funded by the COPEC-UC Foundation “it was possible to demonstrate that by incorporating 1% of acetylated NFCs to the adhesive of chipboards, it substantially improves its mechanical properties, allowing savings of up to 20% resin”, says Juan Cea, Project Engineer.
“Our proposal is to produce and apply demonstratively, and then license, a new additive: chemically modified NFCs by acetylation (acetylated NFCs) with the ability to homogeneously disperse and mechanically strengthen urea-formaldehyde adhesives and bioplastics” concludes Dr. Cabrera.