About the use of recycled or biodegradable filaments for sustainability of 3D printing: State of the art and research opportunities

Additive Manufacturing (AM) and 3D printing are drivers for material savings in manufacturing. Owing to the continuous diffusion of 3D printing driven by low-cost entry-level material extrusion printers, sustainability of a so popular AM technology is of paramount importance. Therefore, recycling 3D printed wastes and 3D parts again at the end of their life is an important issue to be addressed. Research efforts are directed towards the improvement of the biodegradability of 3D printing filaments and the replacement of oil based feedstock with bio-based compostable plastics. The aim of this work is to describe the state of the art about development and use of recycled or biodegradable filaments in 3D printing. Beyond a critical review of the literature, open issues and research opportunities are presented.