Barium Crosslinking in Bio‐Based Sodium Alginate Films: Improved Barrier and Thermal Performance Toward Biodegradable Packaging Applications
Growing environmental concerns associated with petroleum‐based plastics have intensified the demand for sustainable, biodegradable materials for packaging applications. Sodium alginate is a natural polysaccharide with excellent biodegradability, biocompatibility, and film‐forming ability; however, its high moisture sensitivity and moderate thermal stability limit its application. In this study, sodium alginate films were produced by solvent casting and ionically cross‐linked with BaCl 2 solutions at concentrations of 1%, 2%, and 5% (w/v) to evaluate the influence of Ba 2+ on their structural, barrier, and thermal properties. The films were characterized by SEM/EDS, FTIR‐ATR, TGA, and measurements of water vapor absorption, swelling, and mass loss. Cross‐linking promoted denser polymer networks, reducing water vapor absorption from 20% ± 0.55% to 10.5% ± 0.56% at 75% relative humidity, while swelling decreased from 40% ± 2.5% to 29% ± 0.9% after 400 min. TGA indicated improved thermal stability, and mass loss after 24 h in water ranged from 11% to 13%. SEM revealed a more compact morphology with crystalline deposits, while FTIR confirmed ionic interactions between alginate carboxylate groups and Ba 2+ ions. Overall, Ba 2+ cross‐linking significantly improved the physicochemical, barrier, and thermal properties of sodium alginate films, highlighting their potential as biodegradable packaging materials.