Comparative life cycle and circularity assessment of selected bio-based and recycled polymer composites for fused deposition modeling under Finnish conditions

Abstract

This thesis compares the environmental and circular aspects of three different polymer materials for fused deposition modelling (FDM) – virgin PLA, a PLA–wood fibre composite and recycled PET. A cradle-to-grave life cycle assessment (LCA) was performed on Finnish conditions for raw material production, extrusion of filaments, 3D printing and end-of-life treatment. The Environmental Footprint (EF 3.1) method was used to examine the impacts of climate change, fossil resource use, land use and water use. Simplified circularity indicators were added to the environmental results to give a context for the material recirculation potential.

The results show significant trade-offs of the material options. Although PLA has a renewable material origin, it still has environmental impacts from agriculture and processing. The PLA–wood composite decreased the use of virgin polymer but created issues with biomass and recyclability. The recycled PET consistently has lower impact with respect to climate and fossil resources due to avoided virgin materials in the case of the cut-off approach. In all cases, material production is the main concern in terms of environmental impacts. The low-carbon electricity mix in Finland lowers the impact of energy consumption in the printing process. Overall, the results show clear environmental benefits with the use of recycled materials.