Addition of thermoplastic starch (TPS) to binary blends of poly(lactic acid) (PLA) with poly(butylene adipate-coterephthalate) (PBAT): extrusion compounding, cast extrusion and thermoforming of home compostable materials

Development of home compostable materials based on bioavailable polymers is of high strategic interest as they ensure a significant reduction of the environmental footprint in many production sectors. In this paper, the addition of thermoplastic starch to binary PLA/PBAT blends was studied. The compounds were obtained by a reactive extrusion process by means of a co-rotating twin screw extruder. Thermo-mechanical, physical and chemical characterization tests were carried out to highlight the effectiveness of the material design strategy. The compounds were subsequently reprocessed by cast extrusion and thermoforming in order to obtain products suitable for the storage of hot food. The extruded films and the thermoformed containers were further characterized to highlight their thermomechanical, physical and chemical properties. Thermo-rheological, mechanical and physical properties of the material and of the cast film were analyzed thoroughly using combined technique as capillary rheometer, MFI, DSC, VICAT / HDT, XRD, FTIR, UV-VIS, SEM, permeability and, lastly, running preliminary chemical inertness and biodegradation tests. Particular attention was also devoted to the evaluation of the thermo-mechanical resistance of the thermoformed containers, where the PLA / PBAT /TPS blends proved to be very effective, also presenting a high disintegration rate in ambient conditions.