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Evaluation of the quality of polethylene terephtalate flakes for the production of food grade recycled regranulate
Snopková, Martina ; Melčová, Veronika (oponent) ; Kučerík, Jiří (vedoucí práce)
Polyethylene terephthalate (PET) is a widely used plastic, especially to produce PET bottles. However, waste PET bottles pose an environmental risk if they are not well managed. Recycling is an appropriate way to treat PET bottles, ideally by recycling them back into PET bottles. Nevertheless, recycling PET into food-grade recycled PET is challenging and the resulting quality is heavily dependent on the quality of the feedstock, i.e., the PET flakes. This thesis aimed to evaluate the quality of food-grade PET flakes on the EU market. Although the quality of PET flakes has already been the subject of several scientific studies, the analysis of the qualitive parameters of PET flakes has never been applied to such a large area as is the EU market. However, extensive analysis is essential for trend mapping and possible quality optimisation. For the analysis, material from different areas of the EU collected over a period of two years was used. The quality assessment included the quality control methods set out in EN ISO standards and standard operating procedures (SOPs), as well as spectrophotometry, Fourier-transform infrared spectroscopy – Attenuated total reflection (FTIR-ATR), and measurement of intrinsic viscosity. The suitability of each supplier and trends across the batches delivered were assessed. The most important findings included (1) other plastics content is the most problematic quality parameter of PET flakes, (2) other plastics content originates mainly from bottles and is independent of the collection system, (3) a higher degradation rate of PET flakes supplied by Western producers compared to the material from producers located in the East of the EU. A comprehensive analysis of the EU market and quality trends in PET bottle recycling by geographical area and type of collection system were provided. These results will not only be useful for practice, but they could also provide an incentive to improve legislation on the assessment of plastic contaminants or the introduction of more appropriate PET bottle design.
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