Functional Starch-Based Biopolymer Coatings for Sustainable Packaging Applications

Polymer waste poses significant environmental challenges and polymers' replacement with biodegradable biopolymers is therefore crucial. Protective coatings are recognized as a problem in the graphics industry, since they are based on synthetic polymers that are not biodegradable. To be effective, coatings in this industry must meet several key criteria, including stability, functionality, recyclability, and a suitable shelf life. One potential alternative is starch, a highly abundant biopolymer that has been researched for its application in coating preparation. However, its poor mechanical properties have limited its use in this area. This paper investigates the functional properties of starch-based biopolymer coatings enhanced with D-sorbitol and bioactive components: trans-ferulic and L-ascorbic acid. The impact of these additions on the mechanical stability and UV protection potential of the coatings was evaluated. Thermochromic pigments are highly sensitive to UV radiation, making them a useful indicator for evaluating the UV protection factor of a given coating. The colour change of the coated thermochromic prints after UV irradiation was quantitatively evaluated using spectrophotometric analysis. Mechanical properties were assessed through tensile strength, elongation at break, burst strength, and folding endurance. Overall, coatings increased burst strength and improved key mechanical properties depending on the additive combination.