New project sets out to boost rPET content in plastic bottles
From 2030, UK and EU manufacturers will have to ensure that all new PET bottles contain a minimum of 30% recycled PET. The project, therefore, will help develop bottles that meet or even exceed this requirement.
Furthermore, with many major PET bottle manufacturers having outlets in the UK, the project could provide a ‘gateway’ to the global market.
Tackling rPET challenges
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.
With funding from Innovate UK, scientists at Heriot-Watt University will work with Glasgow-based business EnviroPET and the University of Strathclyde, supported by Interface Scotland, on the two-year project.
Plastic 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.
Product shelf life
Founded in 2014, EnviroPET is developing the use of liquid additives, called PET-Yield, that can be added during the PET bottle manufacturing process. These additives can allow the amount of recycled material in bottles to be increased without the loss of properties compared to virgin PET bottles.
The company says the tech ‘could potentially save firms millions’ by reducing the amount of raw material and energy needed to manufacture new bottles.
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,” he said.
“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 behavior. 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’.”
Meanwhile, scientists 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 create a system where processing conditions and blend ratios can be automatically maintained for consistent bottle results.