Progress in design and processing of polyhydroxyalkanoates (PHAs): Home compostable poly(3‐hydroxybutyrate‐co—3‐hydroxyhexanoate) (PHBHHx)/polybutylene succinate‐co‐adipate (PBSA) blend

• Published in: Journal of applied polymer science Vol. 140; no. 23
• Main Authors: Cappiello, G., Aversa, C., Barletta, M., Gisario, A.
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 15-06-2023; Wiley Subscription Services, Inc
• Subjects: Additives; Biocompatibility; compostability; Composting; Containers; Copolymers; Environmental impact; extrusion; Food packaging; Materials science; Nucleation; Permeability; Physical tests; poly(butylene succinate‐co‐adipate) (PBSA); Polybutylenes; Polyester resins; Polyhydroxyalkanoates; polyhydroxyalkanoates (PHA); polyhydroxybutyrate‐co‐hexanoate (PHBH); Polymers; Thermal instability; Thermal resistance; thermoforming molding
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.53933

Polyhydroxyalkanoates (PHA) are biodegradable linear polyesters mainly produced by bacterial fermentation. These materials are biocompatible, non‐toxic, and have a low environmental impact, making them an excellent alternative to fossil‐based plastics in food packaging. Despite their promising characteristics, PHAs have several disadvantages, such as brittleness, slow nucleation process, thermal instability and consequently poor processability. In this article, poly(3‐hydroxybutyrate‐co‐3‐hexanoate) (PHBHx), a copolymer belonging to the class of PHAs, was blended with polybutylene succinate‐co‐adipate (PBSA) and other process additives in order to improve its properties and realize a hot food container compostable in a domestic environment. The material in the pellet form was produced by reactive extrusion with a corotating twin‐screw extruder. The compound was then processed by cast extrusion and the resulting film was thermoformed into a rectangular container. All the semi‐finished products were characterized thermo‐mechanically and with chemical–physical tests, demonstrating good processability, thermal resistance of 100°C, complete impermeability to oxygen, transmission of light radiation less than 30% and high toughness (<5 kJ/m2). In addition, the morphology of the blende was also investigated by SEM and XRD analysis.
Graphic summary of the processes and characterizations performed in the article.