## 3 Results
### Hardness Properties for Virgin and Recycled Polyethylene Terephthalate  
While the variance between the recycled and original is evident, the results are very encouraging. However, it is important to note the 3-9% decrease in the average mechanical properties of the recycled samples in comparison with the virgin samples. Additionally, the increase in standard deviation signifies an increased variability of the recycled material's results. The capacity to mix plastic wastes and require less energy are two areas that must be improved upon within chemical recycling in order to become more sustainable. The use, technological development, and demand of polymers that cannot be recycled should also lessen. Plastic solid waste can only be recycled via mechanical recycling, as per a review of the literature. Through melting, shredding, and re-moulding after washing, organic residue is removed from the polymer and the resultant material becomes ready for manufacturing again once it is compatible with virgin plastic. Chemical recycling refers to the method distinct from standard mechanical recycling which selectively produces fuels, gases or waxes using catalyst, otherwise known as pyrolysis. The present technologies involved in this process exact at high energy cost, which impedes prevalent use. The burning of materials and the resultant collection of energy is another option known as incineration. The inability to reuse or recapitalize are drawbacks of this method, yet its strengths lie in its convenience as mixed wastes require no sorting. While sophisticated laboratories test recycled plastic waste, incineration is not energy efficient. A majority of tests taking place in laboratories occurred in co-operation with the FKF Zrt, of note to the context of this research project. The organisation owns a sophisticated laboratory for testing of recycled plastic waste and closely co-operates with the faculty of mechanical engineering. The impressive properties of the conductive antistatic ABS were highlighted in the previous test, demonstrating its exceptional resistance to high and low temperatures, its impact resistance with dimensional stability, exceptional mechanical strength, and high flow creep resistance. Better even than the ABS was the PET filament. The stoppage of the material flow was found to be the principal issue linked to the rPET extrusion. The HDPE filament would thin and then fracture as the extrudate gradually failed to come out of the die in the middle of the extrusion. Thus, complications were present in the HDPE extrusion. Various elements caused the reduction in hardness, tensile strength, and other properties. One such element could be the recycled filament's properties degrading and other factors include the limit in the inter-layer adhesion and the extrusion interruptions when 3D printing. This paper does not include the individual filament properties as they could not be examined. Flaws in the samples and recycled filament could also be caused by \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Virgin** & **Recycled** \\ \hline Number of specimens & 20 & 20 \\ \hline Average shear yield strength (MPa) & 28,448 & 29,253 \\ \hline Standard deviation & 0.69 & 2.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Shear strength of virgin versus recycled polylactic acid 3D printed specimens. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Virgin** & **Recycled** \\ \hline Number of specimens & 20 & 20 \\ \hline Average hardness (shore D) & 73.10 & 68.71 \\ \hline Standard deviation & 0.725 & 2 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: The hardness of virgin versus recycled polylactic acid 3D printed specimens. nozzles clogging. The potential presence of microscopic impurities in the filament is the principal problem regarding filament re-extrusion as the process was carried out without a filter. There was a lack of coherence in the results that illustrated that the recycled average shear strength was roughly 6.8% higher than the virgin equivalent.