Enhanced UV blocking, tensile and thermal properties of bendable TEMPO-oxidized bacterial cellulose powder-based films immersed in PVA/Uncaria gambir/ZnO solution

The production of UV-resistant films from biomaterials is currently an active field of research. ZnO nanoparticle polymer fillers have been found to improve UV-light opacity. However, using ZnO as a filler is relatively expensive and time-consuming for film preparation. Substituting some of the ZnO nanoparticles with Uncaria gambir extract has been suggested to reduce the cost of film production, as the phenolic hydroxyl group present in Uncaria gambir provides excellent UV resistance. This study characterized dry bacterial cellulose (BC) powder-based films immersed without and with polyvinyl alcohol/Uncaria gambir extract/ZnO (M) solution for 2 and 5 min. It was found that BC/M biocomposites blocked 100% of the UV light while remaining transparent to visible wavelengths. These bendable biocomposite films also presented high tensile and thermal resistance properties. Immersion for 5 min increased significantly tensile strength, elongation at break, and toughness of the biocomposite to 77.2 MPa, 12.3%, and 5.8 MJ/m3, an increase of 130%, 748%, and 2409%, respectively, compared to uncoated BC film. These results suggest the immersion method could provide more efficient, environmentally friendly biocomposite films with significant UV resistance.