Reactive compatibilization and properties of low-cost and high-performance PBAT/thermoplastic starch blends

Poly(butylene adipate-co-terephthalate) (PBAT) is widely used for production of biodegradable films due to its high elongation, excellent flexibility and good processability properties. However, PBAT is costly with prices approximately double or even triple the prices of traditional plastics like polyethylene. Fully biodegradable PBAT/TPS blends are prepared through melt extrusion of PBAT and thermoplastic starch (TPS) to significantly reduced PBAT cost. Effects of reactive epoxy compatibilizer (REC) and preparation methods on morphology and properties of PBAT/TPS blends were determined using scanning electron microscopy (SEM), mechanical analysis, rheological measurement, gel permeation chromatography (GPC), differential canning calorimetry (DSC) and thermal gravimetric analysis (TGA). Results indicated that REC effectively improves compatibility of PBAT/TPS blends and extends polymer chains of PBAT. Blends obtained through two-step extrusion showed a bicontinuous phase structure without phase separation or starch particles, which were observed in blends prepared through one-step extrusion. Excellent mechanical properties were obtained even with high contents of TPS through two-step extrusion in the presence of REC.