Phase inversion fabrication of mung bean starch bioplastics: Effect of glycerol content on mechanical performance, wettability, and soil biodegradation

This study investigates the impact of varying glycerol concentrations on the mechanical, structural, and environmental properties of mung bean starch bioplastics using phase inversion. The results indicate that as glycerol content increases, the bioplastic films exhibit higher hydrophilicity and biodegradability. Specifically, the sample with the highest glycerol content, 9% demonstrates the greatest water affinity, as reflected by a contact angle of 55.34°, indicating a highly hydrophilic surface. This sample also shows the highest biodegradation rate, with 33% weight loss after 9 days, which is attributed to glycerol’s plasticizing effect that increases the porosity and moisture uptake, promoting microbial degradation. Key mechanical properties, tensile strength, Young's modulus, and elongation at break exhibited systematic dependence on glycerol concentration, with tensile strength decreasing from 156.8 MPa at G-1.5–42.0 MPa at G-13.5, consistent with the plasticisation induced disruption of the polymer network, reducing stiffness and increasing flexibility evidenced the tensile strength drops from 156.8 MPa at the lowest glycerol content (0.5% v/v) to 42 MPa at the highest glycerol content (4.5% v/v). Sample which contains (2.5% v/v), strikes the best balance, offering improved mechanical performance while also maintaining a reasonable level of biodegradability and hydrophilicity. This makes it the most promising candidate formulation for applications requiring a combination of flexibility, strength, and environmental sustainability.