The researchers developing this "optimised" carbon fibre recycling system split the process into two phases, these being pyrolysis and oxidation


Carbon fibre reinforced polymer composites are present in products such as wind turbines, aeroplane parts, cars, ships, laptops and mobile phones (Credit: Pixabay)

Researchers at the University of Sydney’s School of Civil Engineering have developed a new and improved recycling process for carbon fibre.

The process, designed for carbon fibre reinforced polymer composites, is said to allow the material to maintain 90% of its original strength while being an optimised method for recycling.

Carbon fibre reinforced polymer composites are present in products such as wind turbines, aeroplane parts, cars, ships, laptops and mobile phones.

These materials are typically disposed of in landfills or by incineration, with the vast majority of existing recycling methods for it causes a major reduction in the mechanical and physical properties of the recovered material.

The study’s lead researcher Dr Ali Hadigheh said: “Globally and in Australia there has been a march towards better recycling processes, however there is often the belief that a material can be recycled an infinite amount of times – this simply isn’t the case.

“Most recycling processes diminish the mechanical or physical properties of materials.

“Until now, it has been impossible to continuously recycle products made of carbon fibres.

“Given that most recycling involves shredding, cutting or grinding, fibres are worn out, decreasing a future product’s viability.

“This presents a huge challenge and threat to our environment, as it has led to the production of virgin carbon fibre which contributes significantly to greenhouse gas emissions.

“To combat this issue and to support a true circular economy, we developed an efficient and cost-effective method for recycling carbon fibre, which is present in tablets through to BMWs.”


Researchers developing an ‘optimised’ carbon fibre recycling system split it into a two-phase process

The researchers involved in the study – which was supported by the Australian Government through the Australian Research Council’s Discovery Early Career Researcher Award fellowship scheme – used a two-phased, optimised process.

The first step was called “pyrolysis”, which breaks down a material using heat, but significantly chars the materials that prevent it from developing a good bond with a resin matrix.

Its second process, oxidation, uses high temperatures to remove this char.

Dr Hadigheh added: “Pyrolysis and oxidation alone are not enough to preserve carbon fibres and these processes have existed for some time already.

“To ensure a high-quality recovery and economic efficiency, thermal decomposition of carbon fibre reinforced polymers need to be guided by analysing the energy required to initiate a chemical reaction in the composite, and separate carbon fibres from the surrounding resin matrix.

“What makes our method so successful is that we have added specific parameters – such as temperature, heating rate, atmosphere or time spent being oxidised and heated – that preserve the functionality of carbon fibre.

“We embarked on the project with the aim of producing high grade, low-cost structural materials made from recycled carbon fibre composites, for use in industries from aerospace and automotive through to sporting goods and renewable energy and construction.”