Effect of Glycerol Concentration on the Properties of Semolina- and Farina-Based Biodegradable Films

This study investigates the properties of biopolymer films derived from semolina and farina, focusing on the effect of varying concentrations of glycerol as a plasticizer. The research fills a gap in the study of grains such as semolina and farina, which have the potential to expand the range of biodegradable materials. Mechanical tests revealed significant differences between the two film types. Farina-based films were notably more ductile, exhibiting an elongation at break of up to two times their original length, but with a low tensile strength of only 1–2 MPa. In contrast, semolina-based films were significantly stiffer, with a maximum elongation at break of 10%. A notable exception was the semolina film with a 25% glycerol concentration, which displayed an exceptionally high tensile strength of 17 MPa. This is a significant improvement over the typical potato starch-based film tested, which breaks at 5 MPa under static tearing. Furthermore, the study examined the films’ morphology, color, SFE, and surface roughness. Free surface energy ranged from 40 to 60 mJ/m2 in the tests, where the influence of the plasticizer was significant. Color tests clearly show yellow discoloration.