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Circular Economy of Composite Materials: turning waste into opportunity

11 May 2021
Article by João Silva and Rui Mendes, project managers.


Fiber-reinforced composites play an important role in global sustainability and energy efficiency1,2. They are the material of choice for producing complex aerospace, automobile, and marine structures, among others, because, as a result of high structural performance and low weight, they allow vehicles to consume less fuel.

However, ironically, the environmental sustainability of composite materials itself is still a challenge, due to the difficulty of recycling and reusing its components, when the products reach the end of their useful life.

Wastes from composite materials - being hybrid materials consisting of fibers and polymeric matrix - do not fit into a specific category of waste in current European legislation, which makes the treatment of this wastes difficult. The solutions for recycling composite material waste, therefore, are not uniform, making the recyclability process much more arduous.

The replacement of thermosetting matrices by thermoplastics is an emerging solution that will have a significant impact on the recyclability of these materials. However, the industrial sector is still in the process of adapting its processes to use this type of matrix 1, 2.

Recycling of composite materials is an opportunity with added value

Currently, there are tons of products with fiber reinforced polymers (FRP) reaching the end of their useful life (i.e., cars, airplanes, wind blades, boats, etc.), in addition to the waste resulting from their production. These materials must be treated intelligently, not only because the legislation, which is increasingly more restrictive at the environmental level, imposes it, but also because reducing its impact is important to reach a viable level of sustainability 1, 2.

Nowadays, composites can be recycled in 3 different ways: mechanically (crushing the composite to later be used as an aggregate), chemical (separation of the fiber matrix, making it possible to recover the fiber and sometimes the matrix) and thermal (separation of the fiber matrix, recovering only the fiber) 3,4,5.

Recycled fibers create new opportunities, namely for carbon fibers, as their prices are more competitive when compared to virgin fibers, having similar properties. It is thus possible to create products at affordable prices, paving the way for the use of these fibers in products destined for other markets, in addition to the luxury or high performance sector.

Making this a reality, however, still depends on the creation of uniform legislation, to guarantee waste streams, sorting and efficient treatments. It is also necessary to win consumer confidence. Despite the general appreciation for environmental merits, the use of recycled raw materials is not always sufficient to convince consumers of the quality of the product 4, 5, 6. That is why it's important to standardize commercial properties and create technical data sheets, so that it is possible to carry out tests and simulations, increasing the confidence of designers and consumers.

For this, the scientific community has a central role, with regard to the dissemination of studies on the optimized combination of recycled fibers with more sustainable matrices for the production of composites on an industrial scale.

Innovation at INEGI is aligned with companies' environmental priorities

Reducing the ecological footprint is a priority for several sectors and, in line with this need, INEGI has also collaborated in the development of solutions in composite materials with recyclable fibers.

The reuse and recycling of glass and carbon fibers, in particular, has already been the focus of several projects. For the aeronautical industry, we are developing composite components of thermoplastic matrix reinforced with carbon fiber, through the maximum valuation of "industrial waste" and with less recourse to virgin raw materials.

Recycling is also central to the development of new products, as evidenced by our collaboration with ALTO - Profiles Pultrudidos, in the development of a prototype of a gutter rail obtained from recycled glass fiber from waste from the pultrusion process in operation in this company.

Reusing raw material, creating new products from what would be considered waste, and at the same time modernizing industrial models, is our vision for creating a circular economy of composite materials.




References

[1] A. Lefeuvre, S. Garnier, L. Jacquemin et al., "Anticipating in-use stocks of carbon fibre reinforced polymers and related waste generated by the wind power sector until 2050,” Resources, Conservation and Recycling, vol. 141, pp. 30-39, 2019.

[2] P. Liu, C.Y. Barlow, "Wind turbine blade waste in 2050”, Waste Management, vol. 62, pp. 229-240, 2017

[3] J. Rybicka et al., "Technology readiness level assessment of composites recycling technologies”, Journal of Cleaner Production 112 (2016) 1001-1012

[4] 10 M. K. Hagnell, and M. Åkermo, "The economic and mechanical potential of closed loop material usage and recycling of fibre-reinforced composite materials,” Journal of Cleaner Production, vol. 223, pp. 957-968 (2019).  

[5] G. Oliveux et al., "Current status of recycling of fibre reinforced polymers: Review of technologies, reuse and resulting properties”, Progress in Materials Science vol. 72, pag. 61-99 (2015)

[6] P. Anh Vo Dong et al., "Economic and environmental assessment of recovery and disposal pathways for CFRP waste management”, Resources, Conservation and Recycling, vo. 133, pag. 63-75 (2018)


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