As a result of the growing awareness of sustainability, the demand of renewable resources for fibre reinforced plastics (FRP) increases. Therefore, bio-based matrix polymers and natural fibre reinforcement have been involved increasingly in research and development. The ESF-Junior-Research-Group “ecoWing” at TU Chemnitz takes this idea even one step further: Developing lightweight composite materials based on natural substances directly, rather than using bio-based, but synthetically engineered materials. To ensure practical relevance, all materials and related processes are tailored to automated production processes.

Low-twist flax fibre flyer-rovings are used to maximise material utilisation of the fibres’ tensile properties. An innovative sizing consisting of an aqueous dispersion containing a seed oil-based polymer is applied to achieve the roving’s tensional and dimensional stability for textile processing. In a subsequent dry fibre placement process, net-shape flax fibre preforms can be layered at a production rate of up to 0,65 m2/min, limiting the cutting waste to a minimal amount.

The same seed oil-based raw materials are used in a newly developed thermosetting epoxy resin matrix, paving the way towards a single-material strategy within the FRP’s polymer content. The resin allows state of the art vacuum infusion processing followed up by a short-cycle 60 min hot curing process at 160 °C. Both mechanical and physical properties of the resulting FRP material show comparable results to conventional and bio-based solutions.

To demonstrate industrial applicability, the application of the flax fibre reinforced seed oil-based epoxy composite is simulated in a linear static finite element analysis of a wind turbine rotor blade. A comparison with glass and carbon fibre manufactured rotor blades provides a first insight in potential use cases of natural substance-based FRPs.