Film blowing of biodegradable poly(hydroxybutyrate-co-hydroxyvalerate) and poly(butylene succinate-co-adipate) blends

International audience

English. INTRODUCTIONPolyhydroxyalkanoates (PHAs) are thermoplastic polyesters produced as carbon and energy storage compounds by microorganisms under nutritional stress. Short-chain-length PHAs, mainly represented by poly(3-hydroxybutyrate) P(3HB) and the copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate)P(3HB-co-3HV) are already commercially available. PHBV can be produced using carbon sources from waste or by-products of agriculture and food industries. This would further promote circular economy because local food waste could be used to make food containers. PHBV is a stiff, brittle, highly crystalline polymer with low thermal stability and a narrow processing window. One strategy that can be adopted to overcome these drawbacks is based on physical melt-blending. In-situ compatibilization can be used to improve the mechanical properties thanks to the enhancement of interfacial adhesion between both phases in binary blends. We developed PHBV/PBSA blends compatibilized with dicumyl peroxide (DCP) and investigated the morphological rheological, thermal, mechanical characteristics, and processability. The formulation, optimized using melt blending, could be processed using film-blowing extrusion. Blown films were then tested in a service situation, corresponding to frozen food packaging.RESULTS AND DISCUSSIONThe solid blends of PHBV and PBSA containing DCP had enough melt strength, making film blowing possible. The viscosity levels increased overall and less thermal degradation was observed. The stiffness of the materials could be largely decreased, elongation at break enhanced, and films stayed flexible even at service conditions of frozen food (-20 °C). Films could be used for the packaging of French fries. No impact of aging at -20 °C on the mechanical properties was found. CONCLUSIONSPHBV/PBSA/DCP blends could be successfully processed by film blowing. Their use properties were adapted to the packaging of French fries. Aging tests in service conditions showed that the performance of the materials was maintained for at least two months. These blends are, therefore, promising materials for food packaging in applications where packaging is necessary.REFERENCES1.Le Delliou, B., Vitrac, O., Castro, M., Bruzaud, S., Domenek, S. J. Appl. Polym. Sci. 2022, 139, 52124.2.Le Delliou, B., Vitrac, O., Domenek, S., "Agricultural, Forestry and Bioindustry Biotechnology and Biodiscovery" Chong, P. A., Newman, D. J., Steinmacher, D. A., Eds. Springer International Publishing: Cham, 2020, 227.