A novel flower to film approach: design and CCD optimisation of starch-based bioplastics reinforced with Hibiscus rosa-sinensis fibre for green packaging

The environmental burden of petroleum-based plastics necessitates sustainable alternatives. This study reports starch-based bioplastic films reinforced with Hibiscus rosa-sinensis flower fibre and plasticised with citric acid and vinegar. Central composite design (CCD) was applied to optimise their mechanical properties. FTIR and XRD confirmed ester bond formation and predominantly amorphous structures, while SEM and optical microscopy showed a uniform morphology. The contact angle values (85°–93°) indicated moderate hydrophobicity. UV–Vis spectroscopy demonstrated improved UV-blocking with higher fibre content, and thermogravimetric analysis confirmed thermal stability up to 300 °C. Soil burial tests showed 50%–70% weight loss within 60 days, with Tukey’s HSD test confirming significant degradation (p < 0.05). The optimised tensile strength of 6.87 MPa and the elongation at break of 42.83%. The films exhibit biodegradability, moderate strength and UV shielding, making them suitable for the short-term packaging of dry and semi-moist foods. This work highlights the underexplored potential of hibiscus flower fiber in sustainable green packaging applications.