Enhancing mechanical performance and environmental sustainability of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) biopolymers using modified bio-oils: A comparative study

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a promising biodegradable polymer for sustainable packaging applications; however, its inherent brittleness and limited flexibility restrict its wider use. Bio-based plasticizers have the potential to improve the performance of this material while reducing dependence on fossil-derived additives. Therefore, this study investigates the effects of different modified bio-oils on the mechanical performance and environmental sustainability of plasticized PHBV materials, with Mesamoll® included as a synthetic plasticizer reference for comparison. Mechanical performance was evaluated through tensile and Charpy impact tests, while thermal properties were analyzed using differential scanning calorimetry. In addition, a cradle-to-grave life cycle assessment was performed using the Environmental Footprint (EF) v3.1 method to compare the environmental impacts of bio-based and synthetic plasticizers. The results showed that bio-based plasticizers significantly improved the processability and mechanical performance of the polymer. Among the investigated formulations, the material containing 20 wt% sunflower and soybean oil epoxidized ester achieved a tensile strength of 24.6 MPa and a strain at break of 2.2%, showing performance comparable to that of the synthetic plasticizer Mesamoll®. The addition of modified bio-oils reduced processing torque and temperature, indicating improved flowability during processing. Thermal analysis revealed changes in melting temperature and crystallinity depending on the type and concentration of plasticizer. The life cycle assessment demonstrated that bio-plasticized materials generally exhibited environmental impacts comparable to or lower than those of the synthetic reference in several impact categories. However, sunflower and soybean oil epoxidized ester showed higher impacts in categories related to fertilizer use, land occupation, and land transformation. The study demonstrates that modified bio-oils are promising alternatives to conventional plasticizers for biodegradable packaging applications. Future research should focus on optimizing bio-oil production and processing routes to further improve material performance and reduce environmental impacts, thereby supporting cleaner production and sustainable material development.