Development of a UV- and thermally resistant biodegradable Starch–PVA nanocomposite for sustainable smartphone casings

Starch-polyvinyl alcohol (PVA) biodegradable nanocomposite film reinforced with SiO₂, ZnO, and TiO₂ nanoparticles was formulated for sustainable casing applications in smartphones. The optimized formulation yielded considerable improvements in functional properties, including 92% UV-B blockage, a 40 °C enhancement in thermal degradation initiation temperature (290 °C for the composite material selected, compared to 250 °C declared for the neat blend), and a tensile strength of 18 MPa with 45% elongation at break. The addition of glycerol (10 wt%) and Vaseline (2 wt%) as plasticizers improved flexibility and decreased water absorption by 30%. 7.5% v/v acetic acid served as an efficient crosslinker to give stability to its structure. Soil-burial tests indicated 80% biodegradation within 60 days. The material thus developed might provide a viable, eco-friendly alternative to petroleum-based ABS/PC casing, thus combining environmental sustainability with competitive mechanical and thermal performance.