Sustainable Reinforcement: A Novel Nanocellulose Modification Route for Biobased Unsaturated Polyester Resins

In this paper, biocomposite materials were developed by reinforcing a bio-based unsaturated polyester resin with cellulose nanofibers, addressing the growing demand for sustainable and high-performance materials. The inherent hydrophilicity and abundant surface functionalities of nanocellulose, while advantageous in some applications, pose challenges for integration with hydrophobic polymer matrices such as unsaturated polyester resins. To overcome these limitations and enhance interfacial compatibility, a novel and eco-friendly surface modification approach was developed, using dimethyl itaconate as an esterification agent. This resulted in significant improvements in the mechanical and thermal properties of the biocomposites, as evidenced by a 23% increase in tensile strength when compared to neat resin, and an elevation in the glass transition temperature of all samples containing modified cellulose nanofibers. These findings emphasise the potential of the developed modification strategy to enhance not only the performance but also the sustainability profile of polymer composites.