Strategies for recycling multi-material polymer blends for additive manufacturing

The rapid advancement of additive manufacturing (AM) technology, combined with the growing accumulation of plastic waste, has generated significant interest in utilizing materials derived from plastic waste and their composites within the AM industry. This paper examines the methods and approaches currently employed in recycling and blending thermoplastic waste into additive manufacturing feedstocks, aiming to enhance understanding and guide future advancements in this field. A systematic literature review including 82 papers from 2014 to 2024 was performed using the Scopus and Web of Science databases. The review findings indicate that approximately 83 % of the research is concentrated in production of new materials combining various polymer waste with recycled bio-sourced materials, recycled fillers or other additives for property enhancement. The evaluation and characterization of these new materials was carry out mostly using 3D printing, predominantly employing fused filament fabrication technology (63 %). The remaining 17 % focus on the improvement of the printing quality and optimization, development or adaptation of 3D printers for the utilization of new materials, and material reprocessability. This review highlight the need of evaluating the behavior of recycled blends over multiple life cycles, the cost and environmental assessments, and primary end-use applications of these materials, including as well as further development and design of printers.