Cellulose nanofibers modified with pendant amine groups as potential reinforcement in bioepoxy for a mechanically tough biodegradable anticorrosive nanocomposite coating

High-performance, sustainable coating materials are important for different applications. Bio-derived epoxies and their nanocomposites offer wide exploitability, in this regard. Carbon-based nanostructures derived from biomass or agricultural waste are achieving considerable demand at present times. This work details the process of extracting cellulose nanofibers (CNFs) from a potential biowaste generated by tea factories. The tunable surface properties of these nanostructures were utilized to introduce amine-blocked isocyanate groups onto the surface of the CNFs (f-CNFs). These f-CNFs were introduced into a bioepoxy (TAE) resin as nano-reinforcing agents in order to study their reinforcing effects. The resulting f-CNF/TAE nanocomposites with very low concentrations of f-CNFs (0.1, 0.2, and 0.3% by weight) exhibited considerable enhancement in their properties. The tensile strength of the nanocomposites increased from 17.3 (for neat epoxy) to 27.9 MPa (61.2% increment) at 0.2% loading of f-CNFs, while the glass transition temperatures were improved to 82–86 °C showing enhanced thermal properties. Furthermore, the nanocomposite coatings displayed good anticorrosive performance at 0.3% loading of f-CNFs with a low corrosion current and potential of 9.65 × 10^–9 (A.cm⁻²) and − 0.3191 V, respectively. Thus, the studied bioepoxy/f-CNF-based nanocomposite has high potential to be used as an anticorrosive coating material for different surfaces.