Flexible and green multilayer paper coating for barrier enhancement of paper packaging

Packaging is critical for the preservation of merchandise like biomedical and food products. However, common packaging materials are typically single-use plastics and rarely recycled or repurposed due to various challenges. This has created a global plastic pollution disaster that affects the health and safety of aquatic and land animals. In this study, a novel multilayer packaging assembly consisting of paper, thermoplastic starch (TPS), and a thin layer (12 μm) of PLA, PBAT, PHBV (all bio-based polymers), or PVOH (as a common commercial polymer for the sake of comparison) were fabricated. The assembly of the multilayer samples were studied using a scanning electron microscope (SEM), and their characteristics, such as the oxygen and water vapor permeation, water and oil Cobb values, seal peel strength (SPS), tear strength (TS), and grease barrier properties were evaluated. Results indicated that the coatings enhanced the dry and wet strengths of the paper. All samples demonstrated considerable grease resistance based on Kit test results. Samples coated with TPS followed by PHBV (PTPHBV) exhibited the best oxygen (0.024 m3/Bar.m2.s) and water vapor barrier (1.79 g/m2.d) properties. Results in this work demonstrated that multilayer assemblies based on paper and TPS provide functional packaging properties making them promising sustainable material options for packaging applications.