m4016 2015 case study carbon fibre recycling
Case Study Carbon Fibre Recycling
Background
We have managed to successfully recycle carbon fibre from its resin composite in a test process that offers a cleaner and more efficient way to recycle composites than pyrolysis
1
Carbon Fibre Industry Worldwide 2011-2020: An Evaluation of Current Markets and Future Supply and Demand, written by Tony Roberts
The demand for carbon fibre has been estimated to triple from 2011 to 2020 by which time, wind energy and the automotive industry will account for 46% of the world’s total consumption1. The lightweight superior strength material is providing an effective alternative to metal across a number of other industries. However, the creation of carbon fibre is energy intensive with its own environmental challenges, and the nature of the thermoset resin system used on fibre-reinforced composite materials makes it extremely difficult to recycle and retain un-degraded fibres. Land Rover BAR build their race boats from carbon fibre. Our life cycle analysis work has highlighted the opportunity to use recycled materials in construction of the moulds where structural integrity is less important, this could lead to a significant cost saving as well as an environmental benefit. Supported by our Exclusive Sustainability Partner 11th Hour Racing, we want to investigate better ways to recycle this important material.
Current recycling methods The key to recycling carbon fibre is the ability to successfully separate the fibres from the epoxy resin. There are two current methods; the first is pyrolysis by which the resin is essentially burned away at high temperatures in the absence of oxygen. The second is the fluidised bed method, by which a high temperature fluid or gas is passed through the material in the presence of air resulting in separation of materials by pyrolysis and oxidation. Both methods are extremely energy intensive requiring temperatures exceeding 400 degrees and 800 degrees respectively. These recycling processes produce degraded fibres that are then ground even finer, downgrading their potential uses. At best, they produce chopped strand mat with short strand fibres, meaning the final product is unsuitable for many structural uses. Other recycled products made from similar chopped strands are the result of new materials woven from waste fibre offcuts.
EXCLUSIVE SUSTAINABILITY PARTNER
Through our tests of these materials, we found that they required significantly more resin than virgin fibres which will affect both the weight of the final product and the overall carbon footprint. Initial test panels manufactured by vacuumconsolidated wet lamination created a recycled carbon panel with 83% resin content. This has a higher embodied carbon, but is cheaper than virgin carbon fibre. More advanced techniques and an effective infusion process would clearly improve this. We wanted to challenge ourselves to find a method that was less energy intensive and resulted in as little fibre shortening or degradation as possible.
Our research Through collaborations with the University of Portsmouth and Adesso, we tested two panels, one made with virgin carbon fibre, the other recycled carbon fibre, both using Adesso’s recyclable epoxy (which performs at 80% of the value of a premium high performance epoxy resin when mechanically tested). We used a chemical process and found that the resin could be dissolved and collected, and the fibres reclaimed without any apparent loss of quality. While this process needs to be developed further, it was carried out at temperatures under 100°C, which indicates there will be significantly lower environmental impact.
Next steps
Summary
The next step is to carry out further tests on a variety of different resins to see if they can also be reclaimed. If, after further testing, different resins are shown to dissolve, we can then take the reclaimed fibres and re-make the panel, and see if there is a drop in the quality by looking at the performance/usability of the reclaimed resins.
We have managed to successfully recycle carbon fibre from its resin composite in a test process that offers a cleaner and more efficient way to recycle composites than pyrolysis, while retaining a highgrade recycled product with minimal degradation. This is a significant finding in working towards a true, closed loop carbon fibre recycling process.
If these further tests are successful, we could look at a wider range of epoxy systems, to see if this can work on multiple products. We could also test infusion and prepreg resins and look at the comparison between recycling processes and their associated environmental impacts. In addition, a large amount of the consumables we use, like gloves and rollers, are contaminated with resin, and hence can only be used once. It would be interesting to see if we can treat the used consumables to remove any resin, so that those could be re-used as well.
To keep up to date with our latest sustainability news, please visit http://www.landroverbar.com/en/sustainability.html All enquiries, comments or suggestions related to the case studies should be directed to [email protected]
#RaisingTheBAR
Background
We have managed to successfully recycle carbon fibre from its resin composite in a test process that offers a cleaner and more efficient way to recycle composites than pyrolysis
1
Carbon Fibre Industry Worldwide 2011-2020: An Evaluation of Current Markets and Future Supply and Demand, written by Tony Roberts
The demand for carbon fibre has been estimated to triple from 2011 to 2020 by which time, wind energy and the automotive industry will account for 46% of the world’s total consumption1. The lightweight superior strength material is providing an effective alternative to metal across a number of other industries. However, the creation of carbon fibre is energy intensive with its own environmental challenges, and the nature of the thermoset resin system used on fibre-reinforced composite materials makes it extremely difficult to recycle and retain un-degraded fibres. Land Rover BAR build their race boats from carbon fibre. Our life cycle analysis work has highlighted the opportunity to use recycled materials in construction of the moulds where structural integrity is less important, this could lead to a significant cost saving as well as an environmental benefit. Supported by our Exclusive Sustainability Partner 11th Hour Racing, we want to investigate better ways to recycle this important material.
Current recycling methods The key to recycling carbon fibre is the ability to successfully separate the fibres from the epoxy resin. There are two current methods; the first is pyrolysis by which the resin is essentially burned away at high temperatures in the absence of oxygen. The second is the fluidised bed method, by which a high temperature fluid or gas is passed through the material in the presence of air resulting in separation of materials by pyrolysis and oxidation. Both methods are extremely energy intensive requiring temperatures exceeding 400 degrees and 800 degrees respectively. These recycling processes produce degraded fibres that are then ground even finer, downgrading their potential uses. At best, they produce chopped strand mat with short strand fibres, meaning the final product is unsuitable for many structural uses. Other recycled products made from similar chopped strands are the result of new materials woven from waste fibre offcuts.
EXCLUSIVE SUSTAINABILITY PARTNER
Through our tests of these materials, we found that they required significantly more resin than virgin fibres which will affect both the weight of the final product and the overall carbon footprint. Initial test panels manufactured by vacuumconsolidated wet lamination created a recycled carbon panel with 83% resin content. This has a higher embodied carbon, but is cheaper than virgin carbon fibre. More advanced techniques and an effective infusion process would clearly improve this. We wanted to challenge ourselves to find a method that was less energy intensive and resulted in as little fibre shortening or degradation as possible.
Our research Through collaborations with the University of Portsmouth and Adesso, we tested two panels, one made with virgin carbon fibre, the other recycled carbon fibre, both using Adesso’s recyclable epoxy (which performs at 80% of the value of a premium high performance epoxy resin when mechanically tested). We used a chemical process and found that the resin could be dissolved and collected, and the fibres reclaimed without any apparent loss of quality. While this process needs to be developed further, it was carried out at temperatures under 100°C, which indicates there will be significantly lower environmental impact.
Next steps
Summary
The next step is to carry out further tests on a variety of different resins to see if they can also be reclaimed. If, after further testing, different resins are shown to dissolve, we can then take the reclaimed fibres and re-make the panel, and see if there is a drop in the quality by looking at the performance/usability of the reclaimed resins.
We have managed to successfully recycle carbon fibre from its resin composite in a test process that offers a cleaner and more efficient way to recycle composites than pyrolysis, while retaining a highgrade recycled product with minimal degradation. This is a significant finding in working towards a true, closed loop carbon fibre recycling process.
If these further tests are successful, we could look at a wider range of epoxy systems, to see if this can work on multiple products. We could also test infusion and prepreg resins and look at the comparison between recycling processes and their associated environmental impacts. In addition, a large amount of the consumables we use, like gloves and rollers, are contaminated with resin, and hence can only be used once. It would be interesting to see if we can treat the used consumables to remove any resin, so that those could be re-used as well.
To keep up to date with our latest sustainability news, please visit http://www.landroverbar.com/en/sustainability.html All enquiries, comments or suggestions related to the case studies should be directed to [email protected]
#RaisingTheBAR
