Preliminary Evaluation of Recycled-Virgin Polylactic Acid 3D Printing Waste from a University Makerspace: Processing and Tensile Response of Printed Specimens

Abstract

Fused filament fabrication (FFF) generates polylactic acid (PLA) waste that, in most cases, is sent to landfill. This study established a preliminary closed-loop recycling system and evaluated the tensile performance of filament produced from the recovered material. Waste PLA was ground in three passes using a benchtop shredder, blended with virgin PLA pellets at 20, 40, 60, and 80 wt.% recycled content, and extruded into 1.75 mm filament at 180 to 185 °C. Two specimens, based on Type I geometry described by ASTM D638, were printed and tested in tension alongside specimens made from commercial virgin filament and laboratory-extruded virgin filament. The extrusion step had an estimated material yield of approximately 91%. All recycled-content blends reached mean tensile strengths around 23.2 to  27.7 MPa compared to 23.5 MPa for commercial virgin PLA, with the 40 wt.% blend as the most promising, whereas laboratory-extruded virgin PLA had the lowest mean strength (18.1 MPa) and apparent tensile modulus (1.35 GPa). Recycled blends were also stiffer on average than either virgin control. Based on the evaluation, which involved two specimens per formulation, the proposed work establishes a first step for practical production of recycled–virgin PLA filaments from makerspace waste and identifies limitations relevant to reliable small-scale recycling.