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Bio-based hybrid tape: Natural fibres in orderly lines

In the course of the collaborative project called “Bio-based hybrid tapes”, the Institute for Textile Technology (ITA) at RWTH Aachen University and its national and international partners have developed an innovative production process for purely bio-based tape to reinforce light metal structural components. The project provides important insights into the use of this tape as a climate-friendly alternative to conventional fibre-glass reinforced tape.

In automobile manufacture, light-weight components made of fibre-reinforced synthetic materials make it possible to reduce the weight of vehicles by up to 30 per cent. In order to ensure that they also meet the same mechanical requirements as conventional components made of steel or aluminium material, tape is used in a targeted way to reinforce areas that are subject to particular strain. While, until now, very energy-intensive glass fibre reinforced tape has been used in manufacture, the process developed in the course of this project allows the production of purely bio-based tape that has virtually the same strength properties.

Engine for progress:

  • First production of almost continuous-fibre reinforced thermoplastic biocomposite materials
  • 100 per cent renewable raw materials
  • Similar to tape in terms of strength
  • Easy to transfer to other material systems

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Photo: Institut für Textiltechnik der RWTH Aachen (ITA)

The flax fibres are spun into yarn for processing so that they acquire the required strength.



New process for a new material

The ITA receives the base products for the newly developed material – industrial-standard flax fibres and a castor oil-based bioplastic – from partners in France. Like all natural fibres, and in contrast to glass and carbon fibres, flax fibres are limited in length, and have to be spun into yarn for processing so that they acquire the required strength. At this point, the ITA also takes a different approach than previously used: since it is essential for the components, which will later be used as reinforcement, that the fibres of the composite material are aligned in the direction of the load, the flax fibres are not twisted but mixed with a bio-based plastic and processed into a fibre strand. In a subsequent step of the process, the synthetic fibres are fused together using ultrasound and the fibre strand is consolidated into a tape. To achieve this, an innovative ultrasonic unit is used, which is produced by EM-Systeme GmbH, a project partner based in Oberhausen. A profile roller propelled by ultrasonic waves warms the plastic up with precision in a continuous process. The melted plastic encases the natural fibres and serves as a matrix for the tape. After the final cooling process, the tape can be wound onto spools.

In a further step of the process, the tape can be tailored to the specific product, positioned and compressed into a composite structure. As a result of the unidirectional orientation of the natural fibres, the innovative ultrasonic welding process and a special arrangement of the fibres, the fibre content can be increased to 70 per cent, thereby improving stability. Components that are subject to strain, such as the casing for backrests or seats for use in cars, can be reinforced in this way to accommodate the load exerted, and this can achieve reductions of up to 20 per cent in terms of the weight and volume of the reinforced structure.

Including an improved carbon footprint

This bio-hybrid tape is virtually as strong as fibre-glass reinforced tape, but has a significantly better carbon footprint. Compared to producing fibre-glass reinforced plastics, the manufacture of natural fibre reinforced plastics consumes approx. 40 per cent less energy and causes 33 per cent fewer CO2 emissions. In addition, when natural fibres grow, CO2 is absorbed from the air and transferred to biomass, thus locking carbon away for the entire product life cycle. The overall savings potential of the project results from the use of biocomposite material and from replacing the usual petro-based plastic matrix with a castor oil-based bioplastic one. In numerical terms, the material developed could reduce CO2 emissions across Europe by 11,400 tonnes per year.


Photo: Institut für Textiltechnik der RWTH Aachen (ITA)

“With the Franco-German research project “Sonic biotapes”, bio-based tape which is suitable for use in structural components can be produced in an ongoing process.”

Marie-Isabel Popzyk and Klaus Vonberg (scientific staff at the Institute for Textile Technology (ITA) at RWTH Aachen University)



Partners and sponsors


Partners:
  • Institut für Textiltechnik der RWTH Aachen University
  • SOFILA
  • SAFILIN FRANCE
  • EM - Systeme GmbH
Sponsors:
  • Bundesministerium für Wirtschaft und Energie (BMWi)