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FlaxWrap: 100% bio-based fibre-reinforced composite materials

Natural fibre-reinforced composite materials (NFRC), on account of their good mechanical properties, are ideally suited for use in car production, especially as their manufacture uses much less energy than carbon fibre reinforced or glass fibre reinforced plastics. Yet even there, the biomaterial is a niche product because of its high manufacturing costs and so far limited range of applications. Its extension to other applications is limited at present by the short fibre length and the resulting low tensile strength. Up to now, efficient product-oriented manufacturing processes have been lacking. As part of the FlaxWrap collaborative project, the Institute of Textile Technology at RWTH Aachen University (ITA) is researching a new process for the commercial manufacture of 100% bio-based NFRC with improved mechanical properties.

Natural fibre-reinforced composites are composed of a natural fibre and a plastic matrix which gives them their final strength. They are medicinally harmless, have a low tendency to split (important in applications in vehicle manufacture) and are stable in cost because of their independence from the oil price. Unlike glass fibre reinforced composites, NFRCs also have less thickness and are significantly eco-friendly, as their production uses 40 per cent less energy and creates 33 per cent less CO2 emissions. However, manufacture is still at an early stage, because the current production and processing techniques for composite materials cannot immediately be converted for NFRC, and up to now no product-oriented processes exist which control their properties.

Engine for progress:

  • 100 per cent based on renewable raw materials
  • Development of an efficient, product-oriented production process
  • Improved material characteristics compared to other NFRCs
  • Potential CO2 savings of up to 20,000 tonnes per year nationwide
  • Increased application potential because of better characteristics

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Photo: Institut für Textiltechnik der RWTH Aachen (ITA)

Blended yarn made from flax and polyamide 11 (PA11) with parallel fibre cross-linking in the fibre core and spiral wrapping with PA11-filament yarn.



Natural fibre-reinforced composites are composed of a natural fibre and a plastic matrix which gives them their final strength. They are medicinally harmless, have a low tendency to split (important in applications in vehicle manufacture) and are stable in cost because of their independence from the oil price. Unlike glass fibre reinforced composites, NFRCs also have less thickness and are significantly eco-friendly, as their production uses 40 per cent less energy and creates 33 per cent less CO2 emissions. However, manufacture is still at an early stage, because the current production and processing techniques for composite materials cannot immediately be converted for NFRC, and up to now no product-oriented processes exist which control their properties.
New material and new manufacturing process

The NFRC developed by the ITA and the related manufacturing process create an entirely new approach. Firstly, the researchers are using a material derived 100% from renewable constituents: it is composed of a polyamide fibre made from castor oil for the matrix and flax fibres as the natural fibre element. Secondly, a completely new production process is being developed as part of the project. Whereas manufacturing processes up to now have relied on binding systems using adhesives or thermoplastic films, which are hot pressed with the natural fibre textile, in the FlaxWrap process an organic sheet is produced which – just like a steel sheet – can be heated up and then shaped. In this way, rejects are reduced to a minimum.

Application in car manufacture

Potential applications for the NFRC developed here are seen in car manufacture, for example in producing form work for back rests, seats, door columns, cockpits or parcel shelves. Currently non-woven materials are used for these applications, but compared to the FlaxWrap product these can only bear smaller loads and are also thicker. Further applications as an alternative to the energy-intensive glass fibre composites are also possible.

The CO2 savings potential of the project arises from several effects: firstly, through the replacement of glass fibre by natural fibre and the replacement of the usual petroleum-based plastic matrix by castor oil-based bioplastics, and secondly through the use of a lower process temperature and – in motor car production applications – a reduction in vehicle weight. Altogether, as much as 20,000 tonnes per year could be saved in this way throughout Germany.


Photo: Institut für Textiltechnik der RWTH Aachen (ITA)

“In the FlaxWrap project, flax fibres and polyamide 11 are processed into an organic sheet. Using the technology developed in the project, high mechanical loads can be achieved in the finished components. The CO2 balance of the new materials is significantly improved through the use of natural fibres and bio-based polymers and the reduced processing temperatures compared with glass fibre materials.”

Dipl.-Ing. Marko Wischnowski, Project Manager FlaxWrap and Robert Brüll, M.Sc.




Partners and sponsors


Partners:
  • DELCOTEX Delius Techtex GmbH & Co. KG, Bielefeld
  • HELP CONSEILS, Notre Dame de Gravenchon, Frankreich
Sponsors:
  • Bundesministerium für Wirtschaft und Energie (BMWi)