The effect of recycled content and type of recycled poly (ethylene terephthalate) (rPET) on the haziness; colour parameters L*, a*, and b*; total colour change; ultraviolet‐visual spectrum (UV‐VIS) absorption; and environmental stress cracking (ESC) of PET bottles was studied. Three series of PET bottles were made at a small scale production facility with same type of virgin PET and three different types of rPET with recycled contents of 25%, 50%, 75%, and 100%. Also, the particle contamination of the produced PET bottles was studied by dissolving bottle fragments and counting the insoluble particles. A linear relationship was found between the haziness of PET bottles and the particle contamination, with a coefficient of determination of 0.96. Linear relationships were also found between the colour parameters L* and b* and the particle contamination of the PET bottles, but the slope differed for each type of rPET. The origin of rPET (mono‐collection or cocollection) seems to be the crucial factor determining particle contamination and colour of the produced bottles. No correlation was found between the recycled content and the incidence of ESC. However, PET bottles in which high intrinsic viscosity (IV) values were measured showed lower chances of ESC than PET bottles with low IV values

The mechanical properties of mechanically recycled polyethylene (rPE) were studied in relation to the composition of the feedstock. This composition varied in six steps from only bottle bodies from a single type of high‐density polyethylene (HDPE) to the complete composition of an industrially sorted polyethylene (PE) product, including other packaging components, other PE‐based packages, sorting faults and residual waste. The rPE with the highest impact resistance was made from the single‐grade bottle bodies. The addition of bodies made from other types of PE already reduced the impact resistance with 11%. All the other stepwise additions of packaging components and faultily sorted objects caused the impact resistance to decrease further. Conversely, the elongation at break grew with the stepwise addition of these packaging components and faultily sorted objects. From the used methods, the best analysis method to accurately determine the polymeric composition of the rPE was found to be near‐infrared‐assisted flake analysis. This method can not only be used to determine the polymeric composition, but due to the strong correlation with the impact resistance, it is also a valuable indicator for the expected mechanical properties of rPE.

The presence of contaminants in polyethylene terephthalate (PET) bottles and derived materials from the various steps in the recycling loop is studied. Based on these measurements, a model is proposed to generically describe the accumulation of these contaminants within closed‐loop recycling schemes for PET bottles. The measured levels of particle contamination and chlorine content of PET bottles, pellets, and intermediate recycling products are used to derive the modelling parameters. Previously determined relations between these measured parameters and critical bottle properties are used to model the effect of the accumulation of the contaminants on the bottle properties. The measurements reveal that the type of collection system influences the accumulation of contaminants in PET bottles greatly. PET bottles in mono‐collection systems accumulate less contaminants than PET bottles in co‐collection systems do. Therefore, PET bottles within recycling schemes using mono‐collection systems can contain more recycled content than those from co‐collection systems, without exceeding acceptation limits on critical bottle properties such as haziness, yellowing, and migration.

Composition of the sorted products and its representativeness 6.1.2 Mechanical recycling of sorted products 6.2 Processing and analysis of rPP material 6.2.1 rPP processing 4 | Public Wageningen Food & Biobased Research-Report 2030 6.2.2 Polymer melt flow results 6.2.3 Mechanical analysis 6.2.4 Physical, chemical and thermal analysis 6.2.5 Colour characterization 6.3 Processing and analysis of rPE material 6.3.1 rPE processing 6.3.2 Polymer melt flow results 6.3.3 Mechanical analysis 6.3.4 Physical, chemical and thermal analysis 6.3.5 Colour characterization 7 Discussion 7.1 Comparison of the results with scientific literature 7.1.1 Recycled materials as blends 7.1.2 Processing 7.2 Analysing recycled plastics 7.2.1 Polymeric composition of recycled plastics 7.2.2 Melt flow properties 7.3 Properties of recycled PE and PP pellets 7.3.1 Commercial vs. high purity recycled plastics 7.3.2 Factors influencing processing and properties of rPE and rPP 7.4 Towards more circularity 7.4.1 Stricter quality control within the current recycling system 7.4.2 Enhancing applicability of existing recycled plastics 7.4.3 A new system based on advanced sorting technologies 8 Conclusion and recommendations Appendix A

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