Processing PLA/P(3HB)(4HB) blends for the manufacture of highly transparent, gas barrier and fully bio-based films for compostable packaging applications

In this study, the extrusion process of PLA/P(3HB)(4HB) blends was studied and the effect on mechanical, thermal and physical properties of the blends containing increasing amounts of P(3HB)(4HB) was evaluated. The blends were prepared by means of a twin screw extruder and subsequently film samples were manufactured using a lab scale cast extruder. A potential industrial application of the studied materials was also validated by testing the films on a pilot thermoforming machine for the production of food containers. The extrusion process demonstrated good processability of blends containing 10%, 20%, and 30% of P(3HB)(4HB). Increasing the amount of P(3HB)(4HB) up to 40% and 50%, processability problems occurred related to tackiness of the materials both during extrusion compounding and during cast extrusion. Both granules and films were characterized and thermo-physical and mechanical properties of the samples are hereinafter reported. The novel polymeric blends are found to be suitable for extrusion compounding, cast extrusion and thermoforming processes. Moreover, the blends exhibit enhanced performances in terms of flexibility and impact resistance as well as protection against gas permeation and boast exceptional transparency. Therefore, the innovative PLA/P(3HB)(4HB) blends prove to be suitable for the production of compostable single-use packaging requiring high transparency and gas barrier.