Physical Characterization and Pre-assessment of Recycled High-Density Polyethylene as 3D Printing Material

3D printing has received lots of attention due to its limitless potential and advantages in comparison to traditional manufacturing processes. This study focuses on the most popular type of home 3D printers, namely fused filament fabrication (FFF) printers, which use plastic filaments as the feedstock. The rather high material cost and large amount of plastic waste generated by FFF 3D printers have driven the need for plastic filaments produced from recycled plastic waste. This study evaluates, in terms of physical characterization, the feasibility of using recycled high-density polyethylene (HDPE), one of the most commonly used plastics, as the feedstock for 3D printers, in comparison with the common acrylonitrile butadiene styrene plastic pellets. In-house extrusion using recycled HDPE pellets and flakes is possible. The diameter consistency and extrusion rate results, along with other physical characterization results, including differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, and water absorption, suggest that making filaments from recycled HDPE pellets is a viable option, as the obtained filament has favorable water rejection and comparable extrusion rate and thermal stability. Existing methods for overcoming the warping and adhesion problems in 3D printing with HDPE were also reviewed. In order to increase the market competitiveness of waste-derived filaments, optimization of the extrusion process, studies on the mechanical and aging properties, and development of a standard characterization methodology and database are crucial.