[Science] Crisp packets made of a new material could be much easier to recycle – AI

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[Science] Crisp packets made of a new material could be much easier to recycle – AI


Crisp packets aren’t widely recyclableJack Sullivan / Alamy By Adam VaughanWhen people took to posting their crisp packets back to Walkers’ crisps to protest that they weren’t easily recycled, the firm took notice and launched collection points for recycling. But the reality is the special scheme has addressed just a tiny fraction of the waste mountain – 3 million of the the 4 billion bags the company alone sells annually in the UK – and they are still not recycled by household recycling schemes. Researchers say they may have come up with a new, greener alternative. The metallised films used for today’s crisp packets, chocolate bars and much other food packaging are great for keeping the contents dry and cool, but hard to recycle as they are made from several layers of plastic and metal fused together. Read more: If Finland struggles to recycle, what hope the rest of the world? “The crisp packet is quite a hi-tech piece of polymer packaging,” says Dermot O’Hare of the University of Oxford. However, recycling it is difficult. While technically the metallised films can be recycled at an industrial level, says UK waste agency WRAP, is it not economically viable to do so widely yet. Advertisement O’Hare and his team’s proposed alternative is a very thin layer, called a nanosheet, made from amino acids and water, applied to a film of plastic (polyethylene terephthalate, or PET, which most plastic water bottles are made of). The benign building blocks appear to make a material safe for use with food, says O’Hare: “In terms of the chemistry that was the breakthrough, making synthetic nanosheets using non-toxic materials.” But he says there will be a long regulatory process, and we should not expect to see the material in packaging for at least four years. Part of the challenge in designing the material was meeting industry demands for a good barrier for gases, to avoid contamination and keep the product fresh. To make the nanosheets, O’Hare’s team created a ‘torturous pathway’, a sort of maze at a nano level that makes it hard for oxygen and other gases to diffuse through. Read more: Throwaway culture: The truth about recycling As an oxygen barrier it appears to perform around 40 times better than metallised film, and the material also fared well in the industry’s ‘crumple test’, which involves flexing and twisting it. The film also has the big advantage of being monomaterial packaging, i.e. only having one material, the PET, which can be widely recycled. The new film is up against rivals, including clay-based materials mined from the earth, though their natural nature means they suffer from concerns over impurities. The race is on to be the greener material of the future, with companies such as Walkers promising fully recyclable or biodegradable packaging by 2025. Journal reference: Nature Communications, DOI: 10.1038/s41467-019-10362-2 More on these topics: chemistry

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