Mechanical Property Characterization of Virgin and Recycled PLA Blends in Single-Screw Filament Extrusion for 3D Printing

Additive manufacturing is an attractive technology due to its versatility in producing parts with diverse properties from a single material. However, the process often generates plastic waste, particularly from failed prints, making sustainability a growing concern. Recycling this waste material presents a potential solution for reducing environmental impact while creating new, functional parts. In this study, the feasibility of creating printable filaments from recycled polylactic acid (PLA) waste and virgin PLA pellets was explored. Filaments were manufactured in the lab using a single-screw desktop extruder with four temperature zones, with compositions ranging from 100% virgin PLA to 100% recycled PLA in 10% composition increments. Test samples were 3D printed using a Material Extrusion 3D printer and subjected to tensile testing in conjunction with digital image correlation to evaluate their ultimate tensile strength, yield strength, Young's modulus, ductility, toughness, and strain distribution. The results indicated that the optimal mechanical properties were observed in specimens made from 100% virgin PLA, 100% recycled PLA, and a 50% virgin/50% recycled PLA blend. Additionally, comparisons with a commercially produced PLA filament revealed that 100% virgin and 100% recycled blends have a 50.33% and 48% higher tensile strength than commercial filament, respectively. However, commercial filaments exhibited higher ductility and toughness than the lab-made extruded filament.