In order to shift to a circular plastics economy, high quality recyclates are required to effectively substitute virgin materials. Current approaches to empirically quantify the substitutability for recyclates are mainly limited by the abundance of virgin material grades along with a lack of adequate application-specific property profiles. In contrast, this work aims for a holistic analysis of the substitution potential of polyolefin recyclates intended for rigid packaging applications. This approach is fundamentally based on the classification of virgin polyolefins into different application-specific sub-groups with defined property windows derived from supplier data sheets, which allows for a generalization within one polymer type without neglecting the various available material grades. Moreover, the findings should provide valuable information for improvements of quality-defining process steps along the value chain of mechanical recycling. Therefore, it is of great importance to correlate the input stream composition of the investigated recyclates with the obtained qualities. The investigation of the substitution potential for selected recyclates clearly highlights the necessity of functional recycling for enhanced quality levels, which especially affects the sorting step in the recycling value chain. This work illustrates that a homogeneous waste stream directly correlates with a high substitution potential. Thus, the development of economically viable sorting strategies which take the functionality of plastic waste products into account must be targeted in future research. Furthermore, the development of detailed application-specific property windows in a joint effort with manufacturers should be pursued, as it allows for a meaningful empirical quantification of the substitutability for recyclates obtained from mechanical recycling.

In light of the circular economy gaining momentum, plastics recycling is regarded as a key solution to keep materials in the loop. Continuous efforts are needed to achieve the packaging waste recycling targets set by the European Union. Hence, this work evaluates the potential of the Icelandic plastics value chain for enhanced recycling rates. In addition to identifying the main challenges and opportunities, a feasibility study was conducted on the expansion of the deposit-return system to Skyr cups, allowing for closed-loop solutions. Based on the status quo, proposals for the improvement of the current waste and recycling system are made. Insights were acquired by semi-structured interviews with nine key stakeholders in Iceland, representing vital groups that influence the plastics value chain. The obtained answers followed the same trend, pointing out that a circular economy within the boundaries of Iceland is currently not feasible. This is mainly due to the strong dependence on international partners in all parts of the value chain except waste collection. However, major improvements are required to enhance the current waste collection rate of 28%. No conclusive evidence was found to justify the suitability of Skyr cups for the deposit-return system, as the disadvantages outweigh theoretically higher collection and recycling rates. Moreover, the extended producer responsibility scheme implemented with the Icelandic Recycling Fund is a valuable tool to enforce a design for recycling of products, enabling higher recycling rates. Despite one recycler operating in Iceland, Icelandic stakeholders consider sorting and treatment of mixed plastic waste as economically more efficient by collaborating with experts throughout Europe. Therefore, they expect that the current practice of exporting the majority of the domestic waste will prevail. On the contrary, the authors propose a comprehensive waste treatment and recycling scheme within Iceland, which requires a sorting step prior to three possible pathways, being (1) mechanical recycling, (2) alternative fuel, and (3) waste-to-energy. The aim of the proposed scheme is a reduction in greenhouse gas impact of plastics entering the waste stage by an efficient and flexible design of the relevant technologies within Iceland.

European legislation, particularly the Packaging and Packaging Waste Regulation (PPWR), is rapidly increasing the demand for high-quality recycled polypropylene (PP) in packaging applications. Achieving such qualities through mechanical recycling remains challenging due to the heterogeneity of post-consumer waste, while the role of intensified washing in the overall decontamination remains debated. This study evaluates the influence of additional sorting and washing intensity on material properties, product performance, and environmental impacts in mechanical recycling of Dutch post-consumer rigid PP. White, clear, and colored fractions were processed under cold and hot wash conditions, extruded, and converted into cups by injection molding and thermoforming. Sorting effectively reduced feedstock heterogeneity, while hot washing slightly improved oxidation stability and ductility. Cup testing showed that the investigated recyclates achieved 77-88 % of virgin polypropylene top load performance. Hot washing removed surface contamination but did not significantly reduce volatile organic compounds or migration levels. A Life cycle assessment (LCA) was performed in openLCA using Ecoinvent background data. The results showed that advanced mechanical recycling, despite higher energy and chemical demand, remained environmentally advantageous, achieving significantly lower climate change impacts compared to virgin PP. However, the recyclate substitution rate in final products was identified as the dominant driver of environmental benefits. Overall, maximizing substitution and sorting efficiency proved more effective for achieving sustainable, high-quality PP recycling than intensifying washing.

Meeting the recycled content targets of the Packaging and Packaging Waste Regulation requires significant improvements in recyclate quality for high‐performance rigid polypropylene (PP) packaging. However, the post‐consumer rigid PP stream is highly heterogeneous, resulting in intermediate recyclate properties when processed as a single stream. This study provides a comprehensive characterization of 20 representative rigid PP packaging products from an Austrian sorting facility, combining rheological, mechanical, thermal, molecular, and chemical analyses to derive a product‐property matrix and sorting implications. The results reveal substantial variability in melt flow rate, stiffness, impact strength, crystallinity, and molecular weight distribution, driven by polymer design and degradation during primary processing. Additional heterogeneity arises from chemical loads, particularly between food and non‐food products, as well as inconsistent stabilizer packages and barrier layers. These findings highlight inherent limitations of object‐based sorting, which cannot reliably infer material properties from external product attributes. Conversely, correlations between spectral‐relevant properties underscore the potential of property‐based flake sorting to classify materials by intrinsic characteristics. A systemic combination of both strategies is proposed: isolating food‐contact materials at the object stage and generating application‐specific recyclate fractions through flake sorting. Developing robust spectral‐property prediction models for PP remains a critical step towards substituting virgin grades.

Mechanical recycling of polypropylene (PP) is constrained by the heterogeneous properties of post-consumer feedstocks. Melt flow rate (MFR) is a key property relevant to processing, and it varies widely across packaging grades, which limits the quality and substitutability of recyclates. This study evaluates near-infrared hyperspectral imaging (NIR-HSI) for predicting MFR in post-consumer PP packaging. Eighty-two rigid PP samples (46 white, 36 clear) with MFR values between 2 and 108 g 10 min⁻¹ were collected from an Austrian material recovery facility. Thirteen different linear and non-linear regression models were examined using median and pixel-wise aggregated spectral representations across the samples. Tree-based models consistently achieved best performances with R² = 0.85, RMSE = 12.4 g 10 min⁻¹ on white samples and R² = 0.61, RMSE = 14.0 g 10 min⁻¹ on clear samples. On the combined sample set, R² = 0.66 and RMSE = 17.3 g 10 min⁻¹ were reached. Informative spectral regions correspond to typical bands of PP. Binary classification at different thresholds (6, 12, 30, 60 g 10 min⁻¹) were also examined and achieved balanced accuracies of 0.82–0.92. Median spectral representations consistently outperformed pixel-wise aggregation. Results demonstrate that NIR-HSI can support grade-directed sorting of post-consumer PP, particularly for opaque white samples, though heteroscedasticity at high MFR values and irreducible outliers represent inherent limitations.

Recycled polypropylene (rPP) has emerged as a promising candidate for potential use in the by far most predominant field of application, namely packaging plastics. Mechanical recycling is acknowledged as one of the most substantial strategies for plastics recycling strategies. This study investigates changes in the analytical profile of rPP along the complete mechanical recycling path by combining different analytical methods, such as gas and liquid chromatography. Consequently, the individual impacts of each processing step were evaluated on the overall contamination removal. Two distinct cup designs were manufactured using injection-molding and thermoforming to assess their potential applications. To this end, migration tests were conducted to evaluate substances that emerged from the cups under realistic conditions. The findings indicate that contamination levels were significantly reduced during mechanical recycling. Furthermore, the persistent contamination in the recycled material did not necessarily result in greater migration from the cups compared directly to virgin cups.