Sustainable TPS/PBAT biocomposites tailored with epoxidized soybean oil for improved mechanical properties

Abstract

The growing demand for eco-friendly substitutes of traditional plastics has further driven the research on compostable and biodegradable films with enhanced functionality. Epoxidized soybean oil (EPSO) was prepared through in situ peracid epoxidation and used as a nontoxic, hydrophobic plasticizer in thermoplastic starch (TPS)/poly(butylene adipate-co-terephthalate) (PBAT) nanocomposites in this study. For better interfacial compatibility and functionality, TPS was filled with nanocrystalline cellulose (NCC) and mixed with EPSO, glycerol, maleic anhydride (MA), rice bran wax (RBW), and stearic acid (SA). The flexible films (50–80 μm) were prepared using blown film extrusion. Structural assessments verified effective soybean oil epoxidation and its homogeneous integration into the polymer matrix. Mechanical analysis indicated that EPSO-modified films, especially 20% glycerol–10% EPSO and 15% glycerol–15% EPSO, exhibited higher tensile strength (13.63 MPa), better sealability, and maintained ductility. Barrier analysis demonstrated these films have lower water vapor permeability and greater hydrophobicity (contact angle up to 108.6°). Thermal analysis (TGA, DSC and FTIR) also confirmed their higher stability and compatibility. Soil burial tests provided proof of excellent biodegradability (>75%), emphasizing the compostability of the films. In general, the synergistic contribution of EPSO and bio-reinforcements resulted in mechanically stable, hydrophobic, and biodegradable films that provide an eco-friendly substitute for single-use packaging and farming purposes.