In Situ Reactive Compatibilization of Thermoplastic Starch/Poly(butylene adipate-co-terephthalate) Blends with Robust Water Resistance Performance

Thermoplastic starch (TPS) has attracted significantattentionas an alternative to fossil-fuel-derived plastics owing to its abundanceand biodegradability. However, its high hydrophilicity impedes itsutilization in packaging applications because of issues such as moistureuptake and inferior barrier properties. In particular, the hydrophilicityof TPS hampers its ability to be compatible with hydrophobic biodegradablepolymers such as poly(butylene adipate-co-terephthalate)(PBAT). Herein, we report a TPS/PBAT blend with enhanced compatibility,mechanical properties, and water resistance, achieved by using insitu reactive compatibilization. We synthesized a reactive compatibilizer,styrene glycidyl methacrylate copolymer (SG), and prepared TPS/PBATblends (50/50) with varying SG contents (0, 1, 3, 5, and 7 parts perhundred resin [phr]). The tensile strength of the TPS/PBAT blend increased,and the size of the TPS domains dispersed in the PBAT matrix decreasedwhen an optimal amount of SG (3 phr) was incorporated into the blend.The complex viscosity, storage modulus, and loss modulus also increasedas the SG content increased, likely due to enhanced compatibilitybetween TPS and PBAT. Furthermore, the water resistance improved uponincorporating SG into the blend, as evidenced by the significant increasesin the contact angle and water vapor barrier properties. Overall,these findings underscore the potential of in situ reactive compatibilizationto improve the intercomponent compatibility and water resistance ofthe TPS/PBAT blends while maintaining their biodegradability and sustainability.