Synergistic enhancement of PLA/PBAT-based active packaging films using yarrow extract and cloisite 30B nanoclay

Abstract

This study investigates the synergistic effects of yarrow (Achillea millefolium L.) extract and Cloisite 30B nanoclay on the structural, mechanical, thermal, antibacterial, and biodegradation behavior of poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) (70/30) blends for active packaging applications. Incorporation of yarrow extract up to 4 wt% improved elongation at break from 5.3% to 10.8% and toughness from 0.93 J cm −3 to 2.13 J cm −3 due to hydrogen bonding and plasticization effects. Differential Scanning Calorimetry (DSC) revealed a reduction in PLA crystallinity from 26.5% to 16.5% and a downward shift in cold crystallization temperature from 70.8°C to 66°C, confirming enhanced chain mobility. Nanoclay addition (0.5-3 wt%) increased complex viscosity and cold crystallization temperature, demonstrating its nucleating and reinforcing effects. Rheological analysis showed a pronounced narrowing of the low-frequency plateau at 1.5 wt% nanoclay, indicating formation of a polymer-clay network. Antibacterial assays showed the lowest MIC and MBC (1/32) for E. coli and S. aureus in P70B30-Y2C1.5, confirming a synergistic release of phenolics from clay surfaces. Enzymatic degradation in PBS with proteinase K demonstrated a weight loss increase from 12% for the neat blend to 38% for the extract-rich sample (Y4C0), while nanoclay reduced the rate to 15–20% at intermediate loading. The optimized P70B30-Y2C1.5 formulation provided a balance of strength, barrier, and antimicrobial properties, making it a promising candidate for biodegradable active packaging applications.