Influence of the Processing Parameters on the Thermomechanical Behavior of Recycled Post-Consumer Multilayer Polymer Waste

Multilayer plastic films (MPFs) are widely used in the food industry. Despite its widespread use, the recycling of MPF remains a challenge due to its complex structure. Solvent-based recycling is more complex and costly than conventional mechanical recycling, which remains the most widely used method despite its technical and economic limitations. This study investigates the conventional mechanical recycling of post-consumer MPF without separating its constituent layers. Samples were prepared using a thermal extrusion cycle with the control of temperature, speed and sample size to improve the melt state, homogeneity and mechanical response of the mixture. The results of the physicomechanical characterization in this research study show that the proper selection of the extrusion parameters for a fine multilayer waste of 2 mm particle size, has a positive impact, for instance, on the final maximum strength of the recycled material, demonstrating an increase of up to 40 and 70% in tensile and flexural properties, respectively. The proposed mechanical recycling of post-consumer MPF without separation of its constituents can produce a material with mechanical properties comparable to those of low-density polyethylene and polypropylene. These findings could significantly benefit the recycling industry by reducing plastic pollution and allowing for creating new products with specific mechanical properties tailored for different applications.