Heriot-Watt University: Project could increase plastic bottles’ recycled content to 30% minimum

Scientists from Heriot-Watt University have been funded by Innovate UK to develop additives and processing methods that will drastically increase the recycled content of plastic bottles.

This will help manufacturers meet the UK and EU requirements that all new PET bottles contain a minimum of 30% recycled PET from 2030.

The team will work with Glasgow-based business EnviroPET and scientists from the University of Strathclyde on the two-year project, which is supported by Interface Scotland.

Plastic drink bottles made from polyethylene terephthalate (PET) are difficult to manufacture with recycled PET content due to the high degree of variation in the recycled plastic feedstock.

This makes it difficult to maintain the necessary uniformity in mechanical and optical properties required, leading to potential issues with bottle failures, carbonated fluids going flat and colour or clarity variations of the final plastic bottles.

ENVIROPET is developing the use of liquid additives, PET-Yield, that can be added during the PET bottle manufacturing process to significantly increase the amount of recycled PET material in new bottles, without the loss of properties compared to virgin PET bottles.

Douglas Craig, managing director of ENVIROPET said: “Our technology will help manufacturers comply with recycling targets and legislation and improve their bottle quality and environmental performance.

“It could potentially save firms millions by reducing the amount of raw material needed for new bottles, as well as the energy resource required for their manufacture.

“All of the major PET bottle manufacturers have outlets in the UK, which means we have a gateway to a global market.”

Professor David Bucknall will lead the Heriot-Watt team to understand how the PET-Yield additives affect PET bottles containing recycled material under laboratory conditions before it is put to the test in a production line.

“We want to solve the problems faced by using more recycled PET content in plastic bottles, which currently results in significantly poorer-quality bottles in terms of their mechanical properties and appearance.

“We’ll be testing how the additive improves the performance of recycled PET blends in a number of critical properties that directly affect the PET bottle behaviour. We will measure gas permeability through the plastic, which has a direct impact on the product shelf-life.

“To have a long shelf-life the plastic must prevent oxygen permeating into the bottle and affecting its content, but also stop CO2 escaping so that carbonated drinks don’t go ‘flat’.

“Our colleagues at the University of Strathclyde will integrate artificial intelligence and deep learning to ensure that the appropriate amount of additive will be included during melt processing of the PET mixtures.

“This will help manufacturers to use this system so that the correct blend ratios and processing conditions are automatically maintained to produce consistently predictable products.

“This project is exciting because we may be able to exceed 30% recycled material in any PET bottle, which would have significant long-term environmental benefits.”

There are over 800 PET manufacturing plants worldwide, including 140 in the UK and the EU. At the moment, over 580 billion new PET bottles are produced each year, most of which contain little or no post consumer, recycled material.

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