Biopolymer‐Coated Paper Composites for Sustainable Packaging

ABSTRACT Conventional plastic packaging, though dominant in food and flexible applications, poses serious environmental concerns due to its persistence and limited recyclability. To address this challenge, this study develops bio‐based coated paper composites as sustainable alternatives. Paper, while biodegradable, lacks adequate barrier properties. To overcome these limitations, in this study, multilayer coatings are fabricated using thermoplastic starch/polyvinyl alcohol (TPS/PVOH) as a base layer and either amorphous polyhydroxyalkanoate (aPHA) or poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) as the top coating, applied via solvent casting on two grades of paper substrates, a 60 GSM printing paper and a 55 GSM thin paper relevant to food packaging application. Mechanical and barrier performances are evaluated through tensile testing, water absorption and water vapour permeability (WVP) measurements. The results show that aPHA coatings exhibit higher tensile strength, whereas PHBV demonstrates greater elongation at break, indicating suitability for rigid and flexible applications, respectively. Both coatings reduce surface hydrophobicity compared to uncoated paper, while the starch base layer enhances film uniformity. Overall, the study demonstrates the potential of bio‐based multilayer paper composites as promising candidates for sustainable and functional packaging solutions.