Sustainable composite foam development: Crosslinked tapioca starch with corn husk sheet reinforcement and chitosan biocoating

Laminar composite foams were developed to create environmentally sustainable materials. Crosslinked tapioca starch was utilized as the foam matrix and reinforcement was provided by corn husk sheets, with a chitosan biocoating subsequently applied to modify the surface. These foams were produced through hot-pressing, with the number of corn husk sheet layers varied (1, 2, and 3) alongside chitosan coating concentrations (1% and 3% by weight). The resultant materials were subjected to comprehensive characterization, where morphology, density, crystallinity, flexural and impact strength, thermal stability, and water absorption properties were evaluated. Refined foam cell structure and reduced structural defects were observed upon incorporating corn husk sheets. Increases in density and mechanical strength, as determined through flexural and impact testing, were documented with higher fiber content. In contrast, thermal stability decreased, while water absorption was reduced. The chitosan biocoating further densified the foam cell structure, increasing density and mechanical strength with increasing concentration, though crystallinity showed no significant change. Notably, the chitosan coating improved water resistance. The composite foam with two corn husk layers and a 3% chitosan coating exhibited optimal performance, demonstrating a 57.32% reduction in water uptake after 20 minutes, a 251.61% increase in flexural strength, and a 195.23% rise in impact strength compared to the unmodified foam. These sustainable composite foams show significant potential for sustainable food packaging, highlighting the synergistic property enhancements achieved through this laminar composite architecture.