Nanoclay‐Reinforced Poly(Butylene Adipate‐Co‐Terephthalate)/Thermoplastic Starch Composite Films for Single‐Use Biodegradable Personal Care Packaging Applications

ABSTRACT Sustainable packaging demand has accelerated the development of biodegradable composites. This study evaluates poly(butylene adipate‐co‐terephthalate)/thermoplastic starch (PBAT/TPS) films reinforced with surface‐modified montmorillonite (MMT) for single‐use soap bar packaging. Films were produced via twin‐screw extrusion using a 70:30 PBAT:TPS ratio with 1–5 wt% MMT. X‐ray diffraction confirmed silicate layer integration within the matrix. MMT incorporation improved melt processability (~36% increase in melt flow index) and significantly enhanced barrier properties. The optimized PTC‐3 formulation (3 wt% MMT) exhibited > 98% UV–visible light shielding and a 27% reduction in water vapor permeability compared to the neat blend. Furthermore, PTC‐3 demonstrated a 14.7% improvement in tensile strength, addressing typical mechanical limitations of starch‐based systems. Soil burial tests confirmed ~33% weight loss after 90 days, indicating accelerated disintegration compared to neat PBAT. Application testing of soap bars over 12 weeks revealed that PTC‐3 effectively preserved product quality by minimizing moisture loss and hardness changes, even under accelerated conditions (45°C). These results demonstrate that nanoclay‐reinforced PBAT/TPS films offer a robust balance of mechanical performance, barrier functionality, and environmental degradability. This work validates bionanocomposites as viable, circular alternatives to conventional plastics in the personal care sector.