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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.

Poly(lactic acid) is one of the most commonly used bioplastics thanks to its mechanical performance and low environmental impact. Strategies to overcome excessive rigidity of PLA are constantly investigated. Poor viscoelastic behavior and brittleness of PLA seriously limit its potential application as a common film material. Herein highly amorphous Poly(3‐hydroxybutyrate‐4‐hydroxybutyrate) (P(3HB)(4HB)) was introduced to improve toughness and reduce brittleness of PLA. Anti‐blocking (silica) and anti‐slipping agent (Ethylene bis‐stearamide (EBS)) were added to improve the processability of the blends, specifically to solve winding issues of the blown film and unfolding of the layflat. In this study three formulations containing PLA and different ratios of P(3HB)(4HB), specifically 10–20–30% were extruded. The mechanical, thermal and surface characterization of the films was performed. The tensile and the tear strength test results show that P(3HB)(4HB) increased the ductility of PLA based films. Increasing amounts of P(3HB)(4HB) provide a toughening effect on PLA/P(3HB)(4HB) blown films without altering transparency of PLA. Moreover, the processing additives proved to be efficient in improving film blowing stability and avoiding tackiness during the winding phase of the film.

This paper studies ternary blends of thermoplastic starch (TPS) with bio-derived polyesters, such as polylactic acid (PLA) and polybutylene succinate-co-adipate (PBSA). The compounds were obtained by means of a co-rotating twin screw extruder and were then reprocessed by cast extrusion and thermoforming in order to obtain, respectively, films and semi-rigid containers. Semi-finished products (compounds and films) and thermoformed products were characterized to evaluate their thermo-mechanical, physical and chemical properties. The films showed good mechanical strength, adequate stiffness / toughness compromise and fair impermeability to oxygen. Furthermore, experimental tests have shown a high disintegration rate of the designed material with considerable mass loss in ambient composting conditions. On the other hand, the thermoformed containers showed inadequate thermal resistance, failing to endure direct contact with hot liquids at 100 ° C.