Recycled plastics qualify as feedstock, but leap forward is still ahead

The current quality of recycled PE and PP is well-suited for various non-food applications. This was concluded from multiple projects that Wageningen Food & Biobased Research has conducted in the last four years. Nonetheless, the demand for recycled plastics lags behind the supply. The main cause: policies to promote the use of recycled plastics and to discourage virgin plastics fall short.

In the Netherlands, packages of polyethylene (PE), such as bottles, are ponderously, separately collected with lightweight packaging waste and mechanically recovered from municipal solid waste. These packages are converted in recycled PE. This recycled plastic is primarily composed of PE (90-95%), of which various types (grades) are present. Additionally several contaminants are present, which largely originates from the packages themselves. Such as labels, caps, closure-rings and other packaging components. Most applications are not affected by the presence of multiple grades of PE and contaminants. Nevertheless, for demanding applications such as bottles, jerrycans and containers for chemicals and hazardous waste, this is a problem.

Injection-moulding applications

Butter tubs and ice cream trays are examples of PP packages. Just as with PE, also recycled PP contains impurities. This affects the melt flow during the production process. This issue is usually solved with additives. The processing is much more challenging when recycled PP is contaminated with non-melting impurities like PET and aluminium. Moreover, the properties of recycled PP are often slightly inferior as compared to virgin PP, even when all possible impurities are excluded.

Competing with virgin plastic

The current quality recycled PE and PP is well-suited for multiple non-food applications. In some applications the properties of colour, gloss and odour are very important and require the recycled plastic to be composed of one type of polymer. Currently, recycled plastic cannot compete well with virgin plastics in case the application is highly demanding, like PE bottles with a high stress cracking resistance and PP flip-top-caps with a thin hinge. This requires the recycled plastics to be free of impurities and to be composed of one grade of polymer. “If you would like to use recycled plastics for these types of applications, then you will have to change the design of the packages, the collection method and the sorting method”, according to Ulphard Thoden van Velzen, senior researcher at Wageningen Food & Biobased Research.

Although recycled PE and PP are technically versatile feedstocks, the recycling companies are far from being outsold, according to Thoden van Velzen: “Buying virgin is easier for most users: it is often a bit cheaper and they can get it exactly as they wish; in the exact quantities and qualities they want to procure.”.

Recycled plastics are therefore enthusiastically used by companies that seek a tangible manner to act sustainable. A large group of companies still waits and lingers.

A need for concerted policies

The results of Wageningen Food & Biobased Research reveal a strong need for coherent European and national policies, according to the researcher: “Make sure that the design-guidelines are evidence- and science-based and monitor compliance by packaging companies. Make sure that it is worthwhile for sorting and recycling companies to produce quality products. Encourage the use of recycled plastics and discourage the use of virgin plastics. And enforce it all. But it also actively involves the civilians: are they prepared to pay for circularity and are they willing to sacrifice convenience for it? And would they accept more rudimentary packed products? Nonetheless, it will demand sacrifices from all of us.”

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