Conventional fibre reinforced composites are usually considered as high-performance materials with high specific stiffness and strength. In contrast mechanical flexible composites can combine high strength with high flexibility regarding bending. Thus, this material class brings a lot of new possibilities. They can cover potential applications in apparel, furniture and sporting goods but also as technical leather, technical canvas and damping elements. By further using renewable resources, the ecological aspect is improved and the enormous innovative capacity is combined with high resource efficiency.
This work addresses the development of such mechanical flexible composites from renewable resources. As matrix system a polymer based on epoxidized vegetable oil with 100 % bio-based carbon content was developed without the usage of catalysts or solvents. The used reinforcements were knitted textiles made of rayon fibres. Composites were successfully manufactured by applying Vacuum Bagging.
For the pure matrix system, a glass transition temperature of 2,5°C was observed by Dynamical Mechanical Analysis. The flexible composites were characterized regarding mechanical properties and morphology. They exhibit strong anisotropic properties, due to the knitted structure of the textile. In knitting direction, the composites were less mechanical flexible (> 4x higher bending stiffness) but exhibited more than 3 times higher tensile strength values.   
The next step is a systematic material optimization based on the established processing-structure-property relationships in order to tailor the composite´s properties for different applications. This includes especially the adjustment of the reinforcement layer (e.g. knitting structure, variation of fibre materials).

The research project is funded by the Austrian Ministry for Climate Action, Environment, Energy, Mobility, Innovation and Technology in frame of the program “Produktion der Zukunft” under contract no. 871403, within the context of the project “Semiflexible and flexible composites based on renewable resources”.