Design, Development, and Fabrication of Cost-Effective Biodegradable Single-Use Plastic Products

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, in this work two different sets of compounds were evaluated. Fist, compatibilized blends of polylactic acid (PLA), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), and 20 wt% talc were studied. The presence of PHBH, a biopolymer obtained by bacterial fermentation and marine biodegradable allows to reduce the environmental footprint of the compound. Due to the susceptibility of PHBH to degradation during extrusion as a result of shear stress, talc was incorporated at a concentration of 20 wt%. Additionally, a second series of compatibilized blends comprising Poly(butylene adipate-co-terephthalate) (PBAT) and Poly(butylene succinate) (PBS) with talc concentrations of 30 and 40 wt% was assessed. These formulations are distinguished by a significantly reduced cost, attributable to the recent decline in PBAT prices and the feasibility of incorporating substantial quantities of talc. The blends were compounded via twin-screw extrusion and used to produce thermoformed trays. Mechanical, thermal and morphological properties of the compounds and semi-finished products were evaluated. The incorporation of a reactive chain extender improves the strength of the compounds, counteracting the stiffening effect of talc. Blends with higher PLA content exhibited superior mechanical performance, with a maximum stress of 40 MPa and an elastic modulus of 1.1 GPa. Blends based on PBAT and PBS presented an elastic modulus of around 300 MPa and a tensile strength of around 25 MPa. The introduction of 40 wt% leads to a drastic drop in ductility in transverse direction. Trays with PBAT/PBS polymeric phase did not fracture during compression tests. With reference to PLA/PHBH trays, only the trays with PLA as the main polymeric phase did not fracture in compression up to deformations greater than 80%. The formulations examined in this study present an optimal balance among cost, stiffness, and environmental sustainability. The PLA/PHBH formulations emerge as the most suitable option when prioritizing a reduced environmental impact, although with a higher production cost. In contrast, formulations based on PBAT/PBS are ideal candidates when minimizing cost is a primary consideration.