Enhancement of thermal stability, UV barrier, biodegradability, and moisture resistance of potato starch–agar bioplastics using biogenic TiO₂ nanoparticles

This study evaluated the influence of biogenically synthesized TiO₂ nanoparticles (NPs) on the structure, properties, and biodegradability of bioplastics made from potato starch and agar. TiO₂ NPs (13.41 ± 1.0 nm, crystalline structure confirmed by X-ray diffraction) were incorporated at 0.674 %, 0.506 %, and 0.434 % concentrations. EDS and X-ray fluorescence confirmed their presence in the bioplastic matrix, while FTIR and Raman spectroscopy revealed interactions with polymer functional groups. TiO₂ addition reduced transparency from 79.1 % (control) to 46.81 % and improved UV-blocking capacity (68.7 % UV-A, 79.1 % UV-B). Water absorption decreased, indicating lower moisture affinity. Thermally, the 0.506 % NP sample showed superior stability with a decomposition temperature of 318.52 °C. Tensile strength decreased from 7.459 MPa (control) to 4.873 MPa, likely due to NP distribution and agglomeration. Biodegradability tests showed 52–60 % degradation in seawater (15 days) and over 76 % in soil (28 days), with the 0.506 % NP sample reaching the highest degradation (79.7 %). These findings highlight TiO₂ NPs’ potential to enhance thermal stability, UV protection, moisture resistance, and biodegradability in sustainable bioplastics.