The Role of Methylene Diphenyl Diisocyanate in the Melt Blending of Poly(Butylene Adipate‐co‐Terephthalate) and Thermoplastic Starch

Thermoplastic starch (TPS) has long been recognized for its challenges in blending with other biodegradable polymers due to issues of compatibilization. This study involved the melt blending of TPS and poly(butylene adipate-co-terephthalate) (TPS/PBAT 50/50) with 4,4′-methylene diphenyl diisocyanate (MDI) acting as a reactive chain extender. The mechanical characteristics, phase morphology, thermal behavior, crystalline structure, and water absorption of the mixes were examined. Increasing the MDI component resulted in enhanced tensile strength from 9.60 to 17.71 MPa, and elongation at break increases from 366.80% to 623.65%. The addition of 0–2 wt% MDI enhances thermal stability with T d peak of starch increase from 327.49°C to 338.34°C. SEM micrographs demonstrated a notable enhancement in interfacial adhesion between the TPS and PBAT phases with the increment of MDI. The relative crystallinity increases from 10% to 13% after the addition of MDI. The presence of MDI decreased the water absorption of the films. Characterization results indicate that the incorporation of a chain extender can improve the performance of TPS/PBAT-MDI bioplastics.