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Easier to recycle toothpaste tubes and crisps packets

Researchers of the University of Oxford in the UK developed a greener alternative to crisp packets, while consumer products company Colgate-Palmolive designed a better recyclable version of a toothpaste tube.

Toothpaste tubes and crisps packages are both notoriously difficult to recycle because they are made of composite materials. Crisp packets contain a metallised film to keep the product dry and cool. But are hard to recycle because they are made of several layers of plastic and metals fused together. Though technically the metallised film can be recycled at an industrial level, it is not economically viable, and therefore not widely done.

Toothpaste tubes are also made of a plastic laminate, usually a combination of different plastics, often sandwiched around a thin layer of aluminium to protect the toothpaste’s flavour and fluoride.

In de case of the crisp packet material, the researchers at Oxford developed a nanosheet, a very thin layer of amino acids and water, applied to a film of PET plastic. The benign building blocks of the amino acids and water make the PET safe for use with food.

To turn the nanosheets into a good barrier for gases, avoid contamination and keep products fresh, the team created a tortuous pathway, a kind of maze at a nanolevel that makes it hard for oxygen and other gases to diffuse through. As oxygen barrier, the new film worked 40 times better than metallised film, and it also survived the crumple test, which involves flexing and twisting it. Because the material is made of only PET, it can easily be recycled.

Due to strict regulations though, the material is not expected to be used in packaging for at least four years.

Colgate-Palmolive turned to another relatively easy recyclable type of plastic, high density polyethylene (HDPE). Unfortunately, this plastic is rigid, making it unsuitable for laminate sheets and soft, squeezable tubes.

Researchers at Colgate realised that they didn’t have to use one grade HDPE. They tested a dozen different combinations, using from six to 20 layers, to find the perfect squeezable material. Once they had developed the right material, they also tested its recyclability, successfully turning it into new bottles.

The new tube will debut under Colgate’s Tom’s of Maine brand in the US in 2020, followed by a select roll-out global markets under its own brand. The company plans to fully convert to recyclable tubes by 2025, with all its products in recyclable packaging.

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