Evaluation of Processability and Functional Properties of Low‐Cost Compatibilized PLA ‐ PHBH Blends for Thermoforming

Single-use food trays are widely employed in take-away and delivery services, contributing substantially to landfill accumulation. Although bioplastic alternatives have been developed, their limited processability and high production costs have hindered large-scale adoption. To address this challenge, compatibilized blends of polylactic acid (PLA), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), and talc were compounded via twin-screw extrusion and used to produce thermoformed trays. Talc was introduced at 20 wt% in all formulations. Three different PLA/PHBH ratios were investigated in the polymeric phase: 20/80, 50/50, and 80/20. Talc reduces the overall cost of the formulations while increasing crystallinity and stiffness. The incorporation of a reactive chain extender improves the impact strength of the compounds, counteracting the stiffening effect of talc. In blends with a polymeric phase of 50% PLA and 50% PHBH, the impact strength exceeded 20 kJ/m2. Blends with higher PLA content exhibited superior mechanical performance, with a maximum stress of 48 MPa and an elastic modulus of 1.2 GPa. Trays with a polymeric phase containing 80% PLA and 20% PHBH did not fracture in compression up to deformations greater than 80%, offering the best compromise between stiffness and impact resistance and demonstrating strong potential for the cost-effective production of bio-based food trays.