Eco-design and composite materials: major movement or an underlying trend?

If flax fibre can help reduce the environmental impact of a composite material, the eco-design of a product accentuates the approach to sustainability. From the plant to development of materials, the production process, the circular economy, and the end of life of composites.

Eco-design and composite materials
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A large family of innovative materials

For over 50 years, engineers have been developing high-tech materials to meet the growing demand of industry and consumers. These innovative assemblies gave rise to hybrid materials called composites. 

The combination of one or more components with different physical and chemical properties aims to improve the performance of a material with high value-added properties. Moreover, adding flax and hemp fibres to polymer composites (with matrix and reinforcements) enhances their mechanical properties.

However, to transmit the desired strength and flexibility to all of the composite material, perfect adhesion to the thermoplastic or thermosetting matrix must be achieved. Most often chemical bonds and flax fibres create a reaction with the polymer matrix. 

While studies show that the solidity, lightness and vibration dampening capacity of flax are widely recognized, it can also dampen sound, probably due to the 70% cellulose content of flax fibre. Researchers are studying the quality of the reinforcement, which depends on its application, in which weaving plays an important role as a structural element.

Weaving can be unidirectional, bidirectional or randomly incorporated when short fibres are added to the composite. This leads to an extremely wide scope of applications and uses for bio-based composites in sports, aerospace, sailing, music and sound, furniture and objects.

Eco-design: from prototype to industrial scale

Without compromising on creativity, designers, entrepreneurs, and engineers have started to use bio-based composites in a global and coherent approach to eco-design, made possible by technical R&D.

For the best environmental practices and on the initiative of CSR consulting firms, the sourcing of the materials and their path - for which short supply chains are preferred - are displayed for full transparency: the production process all the way down to waste reduction, recycling, and the end of life of materials. This is an example of the circular economy and of a life cycle analysis where recycled or reused raw materials are preferred. Their environmental impact is supported by the French Agency for Ecological Transition (ADEME).

Potential applications were developed during product development, with some still in the prototype phase. Thanks to its exemplary eco-design, the Flax chair became iconic in 2015. Its designers, Christien Meindertsma, Enkev, a company specialising in natural fibres, and the sustainable development initiative Label/Breed worked together on developing a rigid seat, 100% renewable (under certain conditions) using a unique natural material. Comprising layers of woven and felted flax and a biodegradable plastic, the chair reinvents the concept of a bio-designed product made from one 60 x 100cm sheet!

By using flax fibre for reinforcement and a 50% natural resin material for the matrix, the young company Notox is promoting eco-design by making custom surfboards using flax-linen. Of course, these eco-friendly initiatives and niche markets are paving the path for others. But the evolution of natural fibre and flax composites, the speed of the manufacturing stages and the use of digital tools are accelerating the development of industrial solutions.

Reducing environmental impact

The eco-design process also means considering the end of life of bio-based composites, i.e., how they will be reused or recycled. While many solutions focus on reducing the use of thermoplastic resins by replacing them with natural materials, we are still far from 100% plant based. Nevertheless, recycling makes reincorporating the fibres possible. In the automotive industry, the same composite material with flax fibres is used several times by reshaping the bio-composite without weakening its reinforcement.

To compensate for the loss of mechanical capacity caused by reusing old fibres, these are then reincorporated, which is both economically and environmentally beneficial. These composites are partially recycled to reduce waste. Since 2021, the industrial group Chomarat, a reference in the world of composites and technical textiles, has been developing alternative solutions for the purpose of sustainable development.

This strategy relies on bio-sourced (natural fibres) or recycled materials in composites and studies their end of life. In partnership with the Group Beneteau, the company launched the production of composites using closed moulding, with a structure of hemp/glass technical reinforcements for maritime transport and shipbuilding. Hemp fibres grown in France have made it possible to reduce environmental impact at industrial scale, whereas the company’s R&D goals regarding the use of recycled fibres and end-of-life composite pieces remain experimental.