Low-cost and high-performance poly(butylene adipate-co-terephthalate)/thermoplastic starch blends prepared by an eccentric rotor extruder: Morphology, rheological behavior, thermal and mechanical properties

Abstract

Due to similar processing and mechanical properties, poly(butylene adipate-co-terephthalate) (PBAT) is expected to be a fully-biodegradable alternative to low-density polyethylene (LDPE) packaging films, thereby alleviating environmental pollution caused by waste packaging films. However, the higher price of PBAT limits its large-scale practical application in the packaging field. Blending with thermoplastic starch (TPS) to prepare PBAT/TPS blends can reduce the cost. In this work, the PBAT/TPS blends with different compositions were prepared using a novel eccentric rotor extruder dominated by an extensional flow field. With increasing the TPS content, a transition from the sea-island phase structure to the bicontinuous phase structure occurred near the composition ratio of 50/50. Moreover, the dynamic mechanical analysis results showed that the compatibility between PBAT and TPS first improved and then deteriorated as the TPS content increased. As a result, the elongation at break first decreased slightly from ~1585% for the PBAT/TPS(90/10) blend to ~1263% for the PBAT/TPS(70/30) blend and dropped sharply to ~130% for the PBAT/TPS(40/60) blend. The knowledge obtained from this study will help us further understand the effect of the TPS phase on the micro-morphology and macro-properties of the PBAT/TPS blends, which is important for the future preparation of high-performance PBAT/TPS blends.