Recycling of polylactic acid (pla) wastes from 3d printing laboratory

Abstract

Material extrusion process, or commonly known as fused deposition modelling (FDM), is the most popular additive manufacturing process to date. Most universities use this technique along with PLA and ABS as the main materials for prototyping. A lot of wastes are generated in this process from support structures and scrapped parts, but they are not usually recycled indoor. Most commonly, these materials are thrown away as landfill. Therefore, the aim of this research was to investigate in-house recycling of PLA wastes using a standard desktop filament extruder. A total of two cycles were carried out (Cycle 0 being the new filament, Cycle 1 and Cycle 2). Mechanical properties, thermal properties and melt flow rate (MFR) were tested on the obtained samples at each cycle. After one recycling (Cycle 1), mechanical properties reduced drastically. This was attributed to hydrolytic degradation which is shown through an increase in MFR and percentage crystallinity. Increasing MFR can be attributed to the reduction in PLA molecular weight. Besides degradation, there were some extrusion and printing issues, which were magnified during Cycle 2. The clogging of extrusion nozzle was due to impurities as no filtering was used during extrusion. Overall, it can be concluded that in-house recycling is feasible, but it should be done with care as the resulting material has reduced mechanical properties.