Water-barrier enhancement in poly(vinyl alcohol) films reinforced with jute and water hyacinth cellulose via citric acid–induced interfacial interactions

Abstract Plastic pollution is a critical global issue, with a significant portion triggered by packaging products. Although poly(vinyl alcohol) (PVA) is a promising biodegradable alternative due to its excellent film-forming ability, flexibility, and non-toxicity, its inherent water sensitivity and comparatively higher cost limit its widespread adoption. This study addresses these limitations by introducing citric acid (CA) to enhance water-barrier performance through hydrogen-bond modification, and by partially substituting PVA with cellulose-rich natural fillers, jute, and water hyacinth (WH), to reduce material cost. The combined use of jute and WH offers complementary advantages: jute contributes higher crystallinity and tensile strength, while WH provides ecological value as an invasive aquatic biomass. Despite their individual use in PVA composites, the synergistic influence of co-reinforcing PVA with both jute and WH, alongside CA-mediated interfacial modification, has not been systematically investigated, which is the focus of this study. Composite films were fabricated with a constant 70/30 (PVA/filler) ratio, both with and without CA addition. The CA-containing film achieved a contact angle up to ~ 79°, compared to pristine PVA (45°), indicating enhanced hydrophobicity. The tensile strength decreased moderately from 46.7 MPa (PVA) to 28–35 MPa for CA-containing films, yet remained within the range suitable for packaging use. The vapor transmission was reduced by ~ 35% and TGA showed higher char yield (up to 34%) for CA-containing films, confirming improved thermal and barrier stability. Overall, the developed bioplastics showcase a sustainable solution to plastic pollution and highlight the viability of using natural resources effectively.