PHB/PLA plasticized by olive oil and carvacrol solvent-cast films with optimised ductility and physical ageing stability

• Published in: Polymer degradation and stability 2022-06, Vol.200, p.109958, Article 109958
• Main Authors: Briassoulis, Demetres, Athanasoulia, Ioanna-Georgia, Tserotas, Philippos
• Format: Article
• Language: English
• Subjects: Additives; Aging (natural); Bio-based films; Biodegradability; Biodegradable materials; Bioplastics; Biopolymers; Chemical structure; Coextrusion; Commercialization; Ductility; Food packaging; Injection molding; Mechanical properties; Olive oil; PHB/PLA blends; Physical ageing; Polyester resins; Polyesters; Polyhydroxybutyrate; Polylactic acid; Polymer blends; Polymers; Solvents; Stability analysis; Thermal behaviour; Thermodynamic properties
• ISSN: 0141-3910; 1873-2321
• DOI: 10.1016/j.polymdegradstab.2022.109958

•PHB / other biobased polymers and additives blends by the solvent casting method•Major differences in mechanical behaviour, variable sensitivity to physical ageing•Compatibility of PHB and PLA compounds with OO, CAR additives at 10/90 w/w ratio•CAR, OO lubricating effect lowers Τg, Tm values and broadens the processing window•PHB/[PLA/OO/CAR] films with high ductility, stability against physical ageing Polylactic acid (PLA) is a bio-based polyester, widely used in various compostable food packaging film applications. Polyhydroxybutyrate (PHB), the most commercialised polymer of the PHA polyesters family, is one of the preferred bio-based polymers for food packaging, mainly because of its biodegradability in natural and controlled environments, and its good gas barrier properties. PHB, being a rather brittle polymer, is suitable for rigid packaging applications, mainly through injection molding processes. PHB may also be used for manufacturing flexible packaging by film casting and film blowing extrusion, through blending or co-extrusion with selected bio-based polymers such as PLA and additives. The potential development of blends of PHB with selected bio-based polymers that may be used for food packaging film applications was investigated in this work. Films made of various blends of PHB with other bio-based biodegradable polymers and additives were produced by the solvent casting method at laboratory scale and evaluated in terms of their mechanical properties and stability, used as “pass-fail” selection criteria. Following the development and evaluation of a second series of selected PHB/PLA blends suitable for films production, it was possible to achieve optimised compositions of PHB/PLA (10/90) blends with olive oil (OO) and carvacrol (CAR) as plasticizing and stabilising additives. The excellent mechanical performance of the selected blends with high ductility and stability against physical ageing, was analysed in depth in terms of their chemical structure and thermal behaviour.