The Influence of PLA and CMC Coatings on Mechanical and Physical Properties of Recycled Packaging Papers

In this study, the effect of polylactic acid (PLA) and carboxymethyl cellulose (CMC) coatings on the mechanical and physical properties of recycled packaging papers was investigated. Paper samples were produced according to the TAPPI T205-SP-02 standard using waste office paper and old corrugated cardboard. The physical and mechanical properties including Cobb values, burst index, tensile index, ring crush test (RCT), corrugated medium test (CMT), and corrugated crush test (CCT) were analyzed. Additionally, the chemical structure of the coated and uncoated papers was studied using Fourier-transform infrared spectroscopy (FTIR). CMC-coated papers exhibited significantly higher RCT, CMT, and CCT values compared to the uncoated samples. Furthermore, PLA hydrophobic characteristics significantly reduced water absorption, as reflected by lower Cobb values in coated samples. The combined PLA-CMC coating substantially enhanced both barrier and mechanical properties compared to uncoated samples. FTIR analysis confirmed chemical modifications in the cellulose matrix as a result of the coating process. These results confirmed that coating of the recycled packaging papers with combined CMC and PLA is a viable approach to improve their strength and water resistance, thereby supporting their potential use in sustainable packaging applications.