A sustainable in situ synthesis of hydrophobic tung oil epoxy bifunctional nanocomposites with potential fire retardant and antioxidant properties

The main focus involves an in situ approach for the preparation of epoxy nanocomposite (EPLNCNF) coatings composed of hybrid Acacia mangium lignin (LN) and Hibiscus cannabinus cellulose nanofiber (CNF) for bifunctional purposes. Hybrid moieties (LN/CNF) were prepared by a chemo-mechanical method using sustainable tung oil epoxy as the base matrix and 0.25 wt. % isophorone diisocyanate (IPDI) as the cross-linker. The solution casting method is used to cast EPLNCNFs on wood, paper and glass for fire retardant testing, with coatings developed on wood exhibiting more protection than paper and glass coatings. Standard ASTM methods, UL94V, one-stop ignition, and thermogravimetric analysis were carried out on the samples, and EPLNCNF nanocomposite coatings were inferred to be potential fire-retardant materials. The surface morphology of the nanocomposite exhibited uniform dispersion and compactness. The spherical-shaped LN, which is intact within rod-shaped CNFs, is distinctly visible and occupies the interstitial voids within the pristine epoxy. Compared with pristine epoxy coatings, hybrid LN/CNF work synergistically within the epoxy matrix with EPLNCNF nanocomposite coatings, exhibiting extensive cross-linking, strong adhesion, hydrophobicity, solvent and chemical resistance, compactness, mechanical stability, no defects, decreased swelling, high crystallinity, antioxidant activity and thermal stability up to 380 °C. DPPH was used to determine that the antioxidant activity of the nanocomposite was 73.50 %. As a result, the shelf life of the materials can increase for longer durations with potential market value.