Toward Compostable Packaging: Biodegradable Polymer Blends with Biobased Components for Household Chemical...

Biodegradable polyester compositions were developed as model systems for potential application in multilayer bottles for household chemicals. Polylactide (PLA) was modified with an epoxy-based chain extender (ECE) to adjust chain topology and molar mass to extrusion blow molding processing and with a carbodiimide hydrolysis stabilizer (HS) to ensure long-term durability. Additional blends with poly-(butylene adipate-co-terephthalate) (PBAT), poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and inorganic fillers (CaCO₃, talc) were prepared to tailor toughness-strength-elasticity balance and processing behavior. Gel permeation chromatography (GPC) revealed that ECE significantly increased weight-average molar mass (M _w) and generated multimodal distributions, while HS introduced low-molar-mass fractions (≈11-50 kg mol^-1), broadening dispersity but providing a capacity for future hydrolytic stabilization. Mechanical testing showed that ECE improved tensile strength and stiffness, HS enhanced ductility and impact resistance, and PBAT incorporation introduced cavitation-assisted plastic deformation, visible in SEM. Thermal analysis confirmed sufficient stability for melt processing (T ₅% > 250 °C), with talc inducing crack deflection and rougher fracture surfaces compared to CaCO₃, which often caused particle pull-out and local voiding. Rheological measurements highlighted that CaCO₃ increased melt flow through interfacial lubrication effects, whereas ECE reduced flow due to branching. Together, the results demonstrate complementary roles of ECE, HS, and fillers in balancing molar mass, thermal robustness, mechanical performance, processability, and morphology, thereby establishing design principles for compostable high-performance packaging materials.