Mitigation Approach of Plastic and Microplastic Pollution Through Mechanical Recycling of Polyethylene-Rich Plastic Fraction Recovered from Marine Environment

Plastic waste is estimated to represent 40–80% of the total amount of marine litter, with polyethylene (PE) and polypropylene (PP) being the most abundant polymeric components. The recovery and recycling of marine plastic debris are therefore essential to mitigate environmental pollution and limit the generation of secondary microplastics. In this work, a mechanical recycling strategy was investigated for the valorization of a polyethylene-rich plastic fraction (PE-rf) recovered from the marine environment, characterized by high heterogeneity and persistent inorganic contamination. Different pre-treatment routes, including cryogenic grinding and planetary ball milling, as well as blending approaches with recycled polyethylene and compatibilizing additives, were explored. The effects of composition and processing on the thermal, mechanical, and morphological properties of the resulting materials were systematically analyzed. The results show that intense mechanical homogenization and chemical compatibilization are not sufficient to overcome the intrinsic limitations imposed by contamination and compositional variability. As a proof of concept, selected formulations were processed into filaments and tested in fused filament fabrication, demonstrating basic 3D printability.