Influence of silica xerogel reinforcement on the water resistance and mechanical properties of cassava peel starch/chitosan bioplastic films: A sustainable waste-derived approach

Petroleum-based plastics used for packaging are made by refining crude oil, resulting in pollutants and greenhouse gases like CO 2 . Combined with a long degradation time, plastic wastes can be a serious environmental and ecological problem. Therefore, more environmentally friendly biodegradable packaging materials are needed to resolve this issue. Starch, although a promising candidate for biodegradable packaging due to its flexibility, transparency, thermoplastic behavior, and affordability, is brittle and has poor mechanical properties. In this study, cassava-based bioplastic films were reinforced by blending with chitosan and adding silica xerogel fillers derived from rice husk ash at 0%, 1%, 3%, 5%, and 10% concentrations. FTIR characterization of the films showed absorption peaks of O−H, C−H, C = O, N−H, C−O, Si−O, and Si−OH, indicating the added chitosan and silica into the starch film. The optimal results for the film tests were obtained with an added 10% silica xerogel, showing a 6% decrease in water absorption (86.8 to 81.7%); 44% decrease in water solubility (57 to 32%); an almost three times increase in the tensile strength (0.56 to 1.55 MPa); and a 27% increase in elongation (49 to 62%). The best biodegradation test was achieved with films without silica addition, showing 53% biodegradation after just 6 days of burial with a 12.40 mg/day degradation rate. These findings highlight the potential of silica xerogel-reinforced cassava peel starch/chitosan films as sustainable, waste-derived bioplastic films with enhanced water resistance and mechanical properties.