MATERIALS / RECYCLING PETplanet Insider Vol. 26 No. 12/25 www.petpla.net 21 Interview with Casper van den Dungen on the study (Di Duca et al): Occurrence of volatile organic compounds (VOCs) and phthalate acid esters (PAEs) in recycled PET: Implications for food packaging materials NIAS in PET and rPET Various factors can lead to the presence and build-up of nonintentionally added substances (NIAS), particularly volatile organic compounds (VOCs) and phthalic acid esters (PAEs), in the rPET matrix. A key driver is thermal degradation that occurs during hightemperature processes such as extrusion and injection moulding. Residual contamination from previous uses can also contribute, while exposure to external substances during collection, storage, or handling may further increase impurity levels. These are the findings of a new study by Di Duca et al., published in the Journal of Chromatography A. PETplanet insider spoke with Casper van den Dungen, Chairman of the NIAS Working Group at PETCORE, about the study and the research insights arising from his work with the NIAS Working Group at PETCORE. PETplanet: The study found significantly higher concentrations of NIAS in recycled PET compared to virgin PET across all processing stages. How alarming are these findings for the PET recycling industry? (Specifically, the total concentrations ranged from 0.33±0.07mg/kg detected in vPET granules to 2.82±0.39mg/kg found in the 100% rPET preforms) Casper van den Dungen: It is very logical that once you use virgin material in following productions that the level of NIAS will increase. Those levels are caused by the handling of that material in the various treatments which are applied on that material. This can be mixing, drying or melting in an injection moulding extruder. This NIAS generation remains at levels far below the level of concern. We have also seen that the analytical techniques used need to be carefully chosen and applied. PETplanet: We know that the samples were sourced from “a wellestablished producer within the European Union”, the study claims. Do you already have data on how big the differences in contamination are between bottles from a DRS and those from a general waste stream? Casper van den Dungen: As you know, the level of foreign materials in a DRS is limited to those which are in the DfR (Design for Recycling Guidelines) of the food-bottles collected with the exception where for example the DRS system is mixing cans with PET bottles. In this case, little pieces of cans will be generated during the decompaction process, by mechanically deforming the bottles & cans. It results in some cross contamination from the coatings present in the can in the PET. But generally, the presence of foreign materials and containers that were used for non food applications is lower in DRS than in a multi-material collection system. Consequently, DRS sets a base that eases the control of NIAS. PETplanet: The study found benzene, a known carcinogen, consistently present in recycled PET samples. What decontamination strategies during the recycling process has the NIAS Working Group identified as most effective for removing or reducing benzene levels, and are current superclean washing and solid-state polycondensation steps sufficient? Casper van den Dungen: Many years ago, the industry has found that the PVC which was used in labels of the bottle was acting as a precursor to create extra benzene in the rPET. After a very effective market information, this precursor was reduced very radically. This results in very low levels of benzene in the current rPET market. The creation and deployment of DfR guidelines - that have identified PVC components are detrimental to the recycling process - has strongly helped the control of benzene and is now the base to anyone willing to put a PET bottle on the market. Furthermore, the recycling technologies have proven to be robust since years enough to cope with such contamination and rPET RECYCLING The total concentrations (calculated as the sum of all individual analytes investigated) detected at various stages of the rPET production cycle. (Source: Di Duca et al, Journal of Chromatography A)
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