In December 2023, the r-LightBioCom project has reached its first milestone identifying flax, hemp and basalt as well as recycled carbon fibres (r-CF), recycled glass fibres (r-GF) and recycled aramid fibres (r-Aramid) as sustainable fibres viable for project implementation. By reaching this milestone, the project has laid essential groundwork for the development of new high-performance composites for meeting the sustainability requirements of the project’s envisaged automotive, infrastructure and aeronautics use cases.
The r-LightBioCom project aims to develop new sustainable high-performance composites with inherent recyclability properties. In this context, the development and implementation of new raw materials that reduce weight and cost and introduce recyclability and sustainability to the resulting high-performance composites form the basis for all project results and the main advances in the state of the art. Therefore, the selection of sustainable fibres suitable for project implementation constitutes an essential building block of the project.
In close consultation with the use case owning project partners CRF (automotive use cases: spoiler and trunk floor), ACCIONA (infrastructure use case: composite pultruded profiles for tunnel lining) and ACITURRI (aeronautics use case: a vertical stabilizer panel), AITEX and HSKL reviewed and analysed appropriate fibres in terms of physical and mechanical properties and their processability into different textile intermediates for application in the respective use cases. Thoroughly evaluating various sustainable fibres, AITEX and HSKL identified two natural fibres, namely flax and hemp, one inorganic pristine fibre, namely basalt, and three recycled high-performance fibres, namely recycled carbon fibres, recycled glass fibres and recycle aramid fibres, as the most fitting choices for achieving the envisaged sustainability goals of the project’s use cases. Preliminary results of the LCA modelling carried out for these fibres by project partner CIDAUT confirm from an environmental point of view that the selected fibres are viable alternatives to conventional fibres.
Selected recycled High-performance Fibres
In the composites industry, a lot of technical fibre waste is generated at the end of products‘ life cycle. Since the recycling process has a smaller footprint than the process for obtaining pristine fibres, recycled carbon fibres, recycled glass fibres and recycled aramid fibres represent a sustainable solution in the framework of the r-LightBioCom project.
In addition to the selected sustainable fibres, pristine carbon fibres[1] and pristine basalt fibres[2] have been chosen to meet specific mechanical requirements.[3] Further, blending recycled fibres with thermoplastic fibres resulted as necessity to reduce brittleness and improve the processability.[4]
To confirm the viability of the selected sustainable fibres for project implementation, textile intermediates were produced considering r-LightBioCom’s use case requirements. To this end, firstly different concentrations of natural, recycled and pristine fibres mixed with thermoplastic fibres were determined to meet mechanical performance and sustainability requirements, and subsequently, yarns, rovings, non-wovens and woven fabrics were manufactured.
Manufacturing non-wovens made from recycled carbon fibres with thermoplastic matrix show a good processability and good fibre dispersion. Challenges in the processability of recycled glass fibre, basalt and recycled aramid have been encountered, necessitating further refinement.
The ongoing tests utilizing bast and basalt fibre blends as reinforcement in polypropylene have shown promising initial results, indicating a significant enhancement in composite properties, particularly suitable for automotive applications.
Addressing the manufacturing of rovings for pultrusion suitable for the infrastructure application, a successful hybridization of recycled fibre rovings with pristine filaments has led to notable improvements in mechanical properties.
In the manufacturing of yarns and fabrics, a sizing application has proven essential to prevent brittleness in recycled carbon fibres during the weaving process. Hybridization of the recycled carbon fibre fabric has been proposed to elevate mechanical properties to meet the stringent requirements of the aeronautics applications.
In conclusion, the carefully selected sustainable fibres proposed for the r-LightBioCom project align with sustainability objectives, as they are of natural and recycled origins. The blends not only meet processability and dispersion requirements for textile intermediates, but also offer potential enhancements through hybridization, particularly in demanding use cases. This represents a significant step forward in the pursuit of sustainable high-performance composites.
For questions and further information about the achievements described in the article above, please contact:
Info-r-LightBioCom@dlr.de
[1] Pristine carbon fibres offer very high tensile strength, high stiffness and low density, which make them suitable for hybridization in recycled yarns and textiles.
[2] Basalt fibres have relatively low environmental impact while offering high mechanical properties. This makes pristine basalt fibres suitable for use as a pristine filament for recycled fibre rovings and chopped fibre for non-wovens
[3] In order to meet high mechanical requirements of applications (e.g. in the aeronautics application), the hybridization of rovings, yarns and fabrics made from recycled fibres with pristine carbon and pristine basalt fibres is being considered.
[4] Due to high brittleness and extreme fineness (5-15 µm), the selected recycled fibres require blending with thermoplastic fibres to enhance their compatibility and processability, e.g. by carding technology. For the r-LightBioCom project Polyamide (PA6), Polypropylene reference (PP-ref) and Polypropylene Malehic Anhydride (PP-MAH) have been selected.
