Scrap PMMA valorization with optimized content of silicon carbide nanofiller in additive manufacturing

Utilizing versatile techniques, such as additive manufacturing (AM) and recyclable materials, is a way of reducing material waste and cost while converting the manufacturing field into being environmentally friendly and sustainable. The latter is essential in the defense domain. Herein, recycled polymethylmethacrylate (PMMA) material was combined with silicon carbide (SiC) nanoparticles in material extrusion AM. The raw materials, nanocomposites, filaments, and specimens utilized and developed were thoroughly experimentally investigated. These included thermal evaluation via thermogravimetric analysis, differential scanning calorimetry, and rheological evaluation via viscosity and melt flow rate investigations. Mechanical evaluation via tensile, bending, Charpy impact, and Vickers micro-hardness tests, as well as structural and morphological examination via μ-computed tomography and scanning electron microscopy, were performed. The aim was to examine the potential of these sustainable materials for use in demanding environments. PMMA/SiC 4.0 wt% (19.8% strength and 41.8% stiffness increase in the flexural test) and PMMA/SiC 12.0 wt% (55.9% Young's modulus increase) were distinguished for their mechanical performance; still, brittleness was increased. The results provided valuable information about the overall mechanical, thermal, and rheological properties of 3D printed sustainable PMMA/SiC nanocomposites, providing important insights for possible use in extreme environments and in defence. • Sustainable PMMA/SiC nanocomposites were produced by Material Extrusion (MEX) 3D printing. • Recycled PMMA was evaluated toward the improvement of the process sustainability. • SiC nanoparticles were evaluated as reinforcement agent for the recycled PMMA, to expand its usability and performance. • Porosity and geometrical accuracy were improved by adding the SiC nanoparticles in the matrix. • Flexural stiffness (41.8%) and strength (∼20%) improved (4 wt. % nanocomposites). Toughness decreased (higher brittleness).