Study of the Structural Property and Biodegradation Relationship of Regenerated Cellulose Nanofibre/Glycerol Laminated Films Incorporating Recycled PLA Waste

The increasing generation of plastic waste from packaging and additive manufacturing, particularly polylactic acid (PLA), necessitates sustainable recycling strategies. This study reports the fabrication of regenerated cellulose nanofibre (RCNF) composite films incorporating recycled PLA waste from 3D printing and glycerol as a plasticiser for sustainable packaging applications. Cellulose nanofibres were dissolved using a sodium hydroxide-urea (NaOH/urea) solvent system and regenerated via a freeze–thaw process, followed by chloroform-dissolved PLA waste phase and lamination with a glycerol-containing coagulants at varying concentrations. The structural properties of the fabricated RCNF/glycerol/PLA films were thoroughly analysed. The Fourier Transform Infrared Spectroscopy (FTIR) analysis demonstrated the existence of intermolecular interactions among cellulose, glycerol, and PLA. Concurrently, the higher glycerol content has enhanced the flexibility and water uptake of the film produced, reaching over 300% at 20% glycerol loading. However, the incorporation of PLA into the film composite has reduced water absorption due to the polymer cellulose chain entanglement. Meanwhile, the soil burial tests revealed that higher glycerol concentrations slowed biodegradation by reduction of the weight loss. In contrast, the increase in the incubation temperatures has intensified the weight loss where 50 °C incubation demonstrated higher weight loss percentage. However, these films showed increased thermal decomposition, suggesting enhanced processability under heat. The findings highlight the potential of upcycled CNF/PLA/glycerol films as an environmentally friendly alternative for packaging applications, contributing to circular material use and reduced ecological impact.