The recycling process could allow the plastics to be reused repeatedly without loss of quality. One of the problems with current plastic recycling methods is that the end product tends to be a lower-quality plastic with worse properties than the original.

Recent figures from the WWF suggest that just 31 per cent of plastic waste is recycled in the UK and the types of plastic that can be recycled varies dramatically depending on the local council.

The degradation in quality also means that, for example, plastic drinks bottles cannot simply be recycled into new drinks bottles continuously. Instead, they are used for other lower-grade products such as water pipes, park benches and traffic cones.

The new method would allow these plastics to be used again for their original purpose. It also has lower temperature requirements and more environmentally friendly catalysts than previous methods.

The University of Bath’s Professor Matthew Jones said: “Most plastic is currently recycled using mechanical methods, where they are chipped into granules and melted down before being moulded into something new.

“The problem is, melting plastic changes its properties and reduces the quality, which limits the range of products in which it can be used.

“Our method of chemical recycling overcomes this problem by breaking down plastic polymers into their chemical building blocks, so they can be used all over again to make virgin plastic without losing any properties.”

The researchers recycled plant-based PLA, which is made from starch or crop waste instead of petrochemicals, and is used in ‘biodegradable’ food packaging and disposable cutlery and cups.

PLA isn’t currently recycled because it’s not yet widely used. However, with the growing awareness of plastic pollution, the demand from consumers for recyclable packaging is growing.

The team has also started trialling a similar process for recycling PET, which is used for drinks bottles.

Dr Paul McKeown, from the University of Bath, and the first author of the paper, said: “PLA is being increasingly used as a sustainable alternative for single-use plastics. Whilst it’s biodegradable under industrial conditions, it doesn’t biodegrade with home composting and isn’t currently recycled, so at the moment it commonly ends up contributing to the tonnes of plastic waste in landfill and oceans.

“There is no single solution to the problem of plastic waste. The approach has to be a combination of reducing, reusing and recycling. Our method of chemical recycling could allow carbon to be recycled indefinitely, creating a circular economy rather than digging more up from the ground in the form of fossil fuels, or releasing it into the atmosphere as a greenhouse gas.”

So far, the technology has only been demonstrated on a small scale. However, collaborators at the University of Birmingham are now working to scale up the system to produce larger quantities of starting chemicals.

Washington State University scientists have previously demonstrated a process where plastic waste can be transformed into jet fuel.

The recycling process could allow the plastics to be reused repeatedly without loss of quality. One of the problems with current plastic recycling methods is that the end product tends to be a lower-quality plastic with worse properties than the original.

Recent figures from the WWF suggest that just 31 per cent of plastic waste is recycled in the UK and the types of plastic that can be recycled varies dramatically depending on the local council.

The degradation in quality also means that, for example, plastic drinks bottles cannot simply be recycled into new drinks bottles continuously. Instead, they are used for other lower-grade products such as water pipes, park benches and traffic cones.

The new method would allow these plastics to be used again for their original purpose. It also has lower temperature requirements and more environmentally friendly catalysts than previous methods.

The University of Bath’s Professor Matthew Jones said: “Most plastic is currently recycled using mechanical methods, where they are chipped into granules and melted down before being moulded into something new.

“The problem is, melting plastic changes its properties and reduces the quality, which limits the range of products in which it can be used.

“Our method of chemical recycling overcomes this problem by breaking down plastic polymers into their chemical building blocks, so they can be used all over again to make virgin plastic without losing any properties.”

The researchers recycled plant-based PLA, which is made from starch or crop waste instead of petrochemicals, and is used in ‘biodegradable’ food packaging and disposable cutlery and cups.

PLA isn’t currently recycled because it’s not yet widely used. However, with the growing awareness of plastic pollution, the demand from consumers for recyclable packaging is growing.

The team has also started trialling a similar process for recycling PET, which is used for drinks bottles.

Dr Paul McKeown, from the University of Bath, and the first author of the paper, said: “PLA is being increasingly used as a sustainable alternative for single-use plastics. Whilst it’s biodegradable under industrial conditions, it doesn’t biodegrade with home composting and isn’t currently recycled, so at the moment it commonly ends up contributing to the tonnes of plastic waste in landfill and oceans.

“There is no single solution to the problem of plastic waste. The approach has to be a combination of reducing, reusing and recycling. Our method of chemical recycling could allow carbon to be recycled indefinitely, creating a circular economy rather than digging more up from the ground in the form of fossil fuels, or releasing it into the atmosphere as a greenhouse gas.”

So far, the technology has only been demonstrated on a small scale. However, collaborators at the University of Birmingham are now working to scale up the system to produce larger quantities of starting chemicals.

Washington State University scientists have previously demonstrated a process where plastic waste can be transformed into jet fuel.