Mechanical Recycling of Waste PLA Generated From 3D Printing Activities: Filament Production and Thermomechanical Analysis

There is a growing need to address waste generated from Fused Filament Fabrication (FFF) 3D printing activities. This study explores the mechanical recycling of waste polylactic acid (PLA) accumulated from failed 3D printing operations and PLA biocomposite filaments containing nanocellulose fibres. FFF 3D printable filaments were produced via melt mixing and extrusion of virgin PLA containing varying amounts of waste PLA. The chemical, thermal and thermomechanical characterisation of each specimen was evaluated using Fourier-transform infrared spectroscopy (FTIR), simultaneous thermal analysis (SDT), dynamic mechanical analysis (DMA), and uniaxial tensile analysis (UTA). A desktop FFF 3D printer was used to fabricate UTA and DMA test specimens. The thermal stability of the filament specimens containing waste derived from the failed 3D prints were comparable with that of the commercial filaments. However, a 11% decrease in the onset of thermal degradation is observed for the filament containing waste biocomposites. The specimens containing waste PLA exhibited higher crystallinity and storage modulus. UTA results revealed similar tensile strength and % elongation, except for the specimen containing 50% waste PLA which exhibited a 29% decrease in tensile strength. This work successfully demonstrates mechanical recycling as a viable waste management strategy for waste materials generated during FFF 3D printing. Mechanical recycling of PLA-based waste materials obtained from 3D printing offers a viable alternative to incineration and landfill disposal. Use of recycled materials also results in reduction of cost and carbon footprint of the final product and alignment to circular economy principles. This study explores mechanical recycling of waste polylactic acid (PLA) generated during filament production and failed 3D prints.image