Effect of Epoxidized Soybean Oil on Biodegradation and Mechanical Performances of Thermoplastic Starch/Poly(Butylene Adipate‐Co‐Terephthalate)

ABSTRACT Combining a bio‐based epoxide soybean oil (ESO) compatibilizer with thermoplastic starch (TPS) significantly enhanced the mechanical performance and biodegradability of poly(butylene adipate‐co‐terephthalate) (PBAT). ESO was synthesized by treating soybean oil with acid, which resulted in a higher degree of epoxidation, reduced residual double bonds, and increased hydroxyl functionality, which improved compatibility and interfacial adhesion between TPS and PBAT with opposing polarities. To prepare a final sample in a melt state, ESO was added to the TPS/PBAT binary blends with a weight fraction of 70/30 in a melt state to form the resulting composite film. The improved compatibility between the two polymers is confirmed by FTIR data, which demonstrated that ESO offers hydrogen bonds between TPS and PBAT. Thermal analysis and rheological measurements were employed to examine the effect of the ESO compatibilizer in the binary blends of TPS and PBAT. The addition of ESO improved the mechanical properties of the TPS/PBAT polymer blend. Upon addition of 7 wt% ESO, the elongation at break of the TPS/PBAT blend was increased by ~81.8%, showing noticeably superior elongation behavior compared to blends without ESO. The measurements of biodegradation behavior revealed that the biodegradation rate of PBAT was considerably improved from 31.6% to 78.5% by adding TPS and 7% ESO compatibilizer, which can be employed in the agricultural industry as a biodegradable mulch film.