| Abstract [eng] |
The main objective of this work was to investigate the potential for the recycling of the plastic waste generated by fused deposition modeling technology. Following a literature analysis, it was decided to produce recycled thermoplastic filament by extrusion of shredded PLA waste. A methodology was developed experimentally to achieve the target thermoplastic filament diameter of 1,75 mm under optimal extrusion parameters (speed and temperature). After successful extrusion, an analysis of the printability of the recycled thermoplastic was carried out. However, during the printing process, a tendency for the printer nozzle to clog was observed. Due to the problems encountered during printing, a microscopic analysis of the produced thermoplastic filament was performed. The analysis revealed impurities from the shredding process which, due to the different melting temperature compared to PLA, clog the printer nozzle during printing. For this reason, the produced PLA filament could not be used for further investigations. In order to assess the impact of the use of recycled PLA on the printing process, the mechanical properties of the printed products and the economic benefits, it was decided to use Prusament 100 % recycled PLA thermoplastic filament for further studies. This thermoplastic was chosen as an excellent alternative to the recycled plastic filament produced in the study, as it is made from the first recycled waste from the PLA printing process without the use of any additives. To investigate the effect of recycling on the mechanical properties, tensile and flexural tests were chosen in respect of ASTM D638-14 and ASTM D790-17 standards. For comparative analysis, identical samples were printed from virgin Prusament PLA plastic. In order to collect thorough data and results, the samples were printed with three different orientations on the printing platform. The analysis of the results showed that, regardless of the printing orientation, the tensile strength, the maximum sustained force and the tensile modulus of the virgin PLA specimens were similar or higher compared to the recycled PLA specimens. The analysis of the flexular test results showed that the recycled PLA samples in the second orientation exhibited similar mechanical properties to the virgin PLA samples. However, the first and third orientation recycled PLA specimens exhibited a lower flexural strength, a lower maximum sustained force and a lower flexural modulus compared to the virgin PLA specimens. Although this study was not successful in producing a filament of recycled PLA thermoplastic that would provide a stable printing process, the results obtained with the Prusament alternative suggest that, in the context of high waste and production volumes, recycling of PLA is not only environmentally beneficial, but also economically viable. |
