Stable aqueous dispersions of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) polymer for barrier paper coating

The demand for alternatives to single-use, synthetic, and non-degradable plastic packaging is continuously increasing. Paper products offer an environmentally friendly solution, however, typically do not meet strict barrier and other physical property performance demands unless coated with polymeric films, typically conventional polyolefins. Replacement of the conventional plastic film coating with bio-based and biodegradable polymers, such as poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) could provide competitive packaging properties while meeting sustainability objectives. In this study, PHBV is dispersed and stabilized in water for further environmental and coatability benefits. Four 10 wt% solids waterborne dispersions of PHBV with sodium dodecyl sulfate surfactant and guar gum rheological modifier were prepared and remained stable for several weeks at room temperature when evaluated using rheological study and particle size analysis. Manila paper substrate was coated, evaluated, and compared to uncoated paper. A smooth, transparent film, with great substrate adhesion and flexibility was obtained. Wet mechanical properties, water vapor permeability, oil resistance, and water absorption all displayed excellent results for barrier packaging applications, with substantial improvement over uncoated paper. Overall, the waterborne PHBV dispersion and paper coating exhibited promising results as a sustainable packaging option.