Sustainable Reinforcement: Advancing Nanocellulose Modification for Biobased Unsaturated Polyester Resins

In this study, biocomposite materials were developed by reinforcing a biobased unsaturated polyester resin with cellulose nanofibers to meet the demand for sustainable, high-performance materials. The inherent hydrophilicity and abundant surface functionalities of nanocellulose pose challenges for integration with hydrophobic polymer matrices, such as unsaturated polyester resins. To address this, a purification-free, one-step modification method was introduced in which dimethyl itaconate acts simultaneously as an esterification agent and solvent. The resulting reaction mixture was used directly as a reactive diluent, eliminating hazardous solvents and additional purification steps. Incorporation of modified nanocellulose resulted in notable performance enhancements, including a 23% increase in tensile strength at 0.3 wt % of modified nanocellulose compared to the neat resin and elevated glass transition temperatures across all samples. These findings emphasize the potential of the developed modification strategy to improve performance and sustainability, helping bridge the gap between sustainable polymer composites and their wider industrial application.