Tensile and Structural Properties of Antioxidant- and CaCO₃-Modified Polyethylene Films

The demand for modified packaging materials increases annually. At the same time, there is growing interest in the development of functional packaging. The incorporation of modifiers, stabilizers, and fillers into polymer matrices can enhance the functionality of the material but may also negatively affect its safety. Polymers are susceptible to degradation, which negatively affects their strength and tensile properties under external factors (physical, chemical or environmental). Packaging containing antimicrobial and antioxidant agents is among the most promising, as it contributes to the product quality during storage. Films based on calcium carbonate (CaCO₃) and dihydroquercetin (DHQ) remain insufficiently studied, despite their potential. Such materials are especially relevant for fatty products with a large contact surface area, including butter, cheese, and other solid high-fat foods. This study aimed to comprehensively investigate the structural and tensile properties of polyethylene films modified with varying contents of CaCO₃ and DHQ. The films were produced via blown film extrusion using a laboratory extruder (SJ-28). Surface analysis was performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Fourier-transform infrared (FTIR) spectroscopy was used to examine the film's composition. The results showed that the introduction of more than 40.0 wt.% of CaCO₃ into the polymer base affected the strength properties. The conducted studies of the physical and mechanical properties of LDPE film samples filled with CaCO₃ showed significant changes in the samples containing more than 50.0 wt.% of the filler, with an increase in strength of more than 40.0%. The relative elongation at break after 50.0 wt.% decreased by more than 75.0%. These results indicate that to achieve the best strength properties for packaging materials, it is recommended to fill them to a maximum of 40.0 wt.%. The introduction of the antioxidant DHQ had almost no effect on the strength of the modified films. SEM analysis of films with high CaCO₃ content and DHQ revealed visible antioxidant particles on the film surface, suggesting enhanced antioxidant potential at the interface between the film and dairy products. AFM analysis confirmed that a CaCO₃ 40.0 wt.% content altered the surface roughness and heterogeneity of the films. FTIR spectroscopy revealed that the incorporation of CaCO₃ influenced the overall spectral profile of polyethylene, resulting in decreased peak intensities depending on the concentration of the filler. Based on these results, the modified polyethylene-based film with CaCO₃ and DHQ shows potential for use as food packaging with antioxidant properties.