Solo water-gelatinized starch enhances the barrier properties of starch/PBAT

Glycerol-plasticized thermoplastic starch blending with biodegradable materials reduces costs and enhances toughness at the expense of deteriorating barrier properties. Herein, solo water-gelatinized corn starch (GCS) was melt-blended with polybutylene adipate terephthalate (PBAT) at 130 °C, and subsequent dehydration converted GCS into retrograded corn starch (RCS), yielding RCS-filled PBAT composites. As a barrier filler, RCS dispersed in smaller particles, combined with an interfacial compatibilizer, pentaerythritol monolaurate (PM), dramatically enhances the barrier properties. At 40 % RCS content, the oxygen permeability coefficient decreases to 0.78 × 10^-14 cm³·cm/cm²·s·Pa, which is about one order of magnitude lower than that of neat PBAT. Meanwhile, the water vapor permeability coefficient, light transmittance, and haze are all comparable to neat PBAT. Although the mechanical properties of RCS-filled PBAT decreased, the tensile strength and elongation at break remained at 9.60 MPa and 462.19 % (30 % RCS), respectively. This work presents an innovative and cost-effective approach for starch-filled biodegradable polymers.