Biodegradable Plastic from Gadung Tuber ( Dioscorea hispida Dennst): Enhanced Properties with Chitosan and Nanosilver Synthesized from Shallot Skin

Abstract The growing concern over non-degradable plastic waste has spurred the development of environmentally friendly alternatives. This study investigates the production of biodegradable plastic films from gadung tuber ( Dioscorea hispida ) starch reinforced with chitosan and nanosilver synthesized from shallot skin extract. The objective was to enhance the mechanical, physical, and biodegradability properties of starch-based bioplastics through natural polymer blending and green nanotechnology. A green synthesis method was used to produce nanosilver (AgNPs) with an average particle size of 49–51 nm, confirmed via UV-Vis spectroscopy and particle size analysis. Films were prepared through casting and drying, incorporating varying concentrations of chitosan (4, 6, and 8 g) and AgNPs (1, 3, 5, and 7 mL). Mechanical and physical evaluations revealed that the optimal formulation (6 g chitosan and 7 mL AgNPs) attained a tensile strength of 33.97 MPa, exceeding national and international standards. The 8 g chitosan and 3 mL AgNPs treatment yielded the highest elongation (123.68%) and lowest water absorption (18.15%), indicating excellent flexibility and moisture resistance. However, increasing AgNP content reduced biodegradability to 16.11%, reflecting a performance-environmental trade-off. This research demonstrates the promise of blending native starch with bio-waste-derived additives to produce high-performance biodegradable plastics, highlighting the importance of achieving a formulation balance to ensure environmental compatibility.