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

Abstract

Thermoplastic starch (TPS) has attracted significant attention as an alternative to fossil-fuel-derived plastics owing to its abundance and biodegradability. However, its high hydrophilicity impedes its utilization in packaging applications because of issues such as moisture uptake and inferior barrier properties. In particular, the hydrophilicity of TPS hampers its ability to be compatible with hydrophobic biodegradable polymers 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 in situ reactive compatibilization. We synthesized a reactive compatibilizer, styrene glycidyl methacrylate copolymer (SG), and prepared TPS/PBAT blends (50/50) with varying SG contents (0, 1, 3, 5, and 7 parts per hundred resin [phr]). The tensile strength of the TPS/PBAT blend increased, and the size of the TPS domains dispersed in the PBAT matrix decreased when an optimal amount of SG (3 phr) was incorporated into the blend. The complex viscosity, storage modulus, and loss modulus also increased as the SG content increased, likely due to enhanced compatibility between TPS and PBAT. Furthermore, the water resistance improved upon incorporating SG into the blend, as evidenced by the significant increases in the contact angle and water vapor barrier properties. Overall, these findings underscore the potential of in situ reactive compatibilization to improve the intercomponent compatibility and water resistance of the TPS/PBAT blends while maintaining their biodegradability and sustainability.