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Spinning of hybrid yarns from short Carbon Fiber for composites

Fachliche Zuordnung Polymere und biogene Werkstoffe und darauf basierende Verbundwerkstoffe
Förderung Förderung von 2013 bis 2017
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 237692119
 
Erstellungsjahr 2017

Zusammenfassung der Projektergebnisse

As the global consumption of carbon fibre (CF) for composites is increasing steadily, an integrated solution to reuse the CF is required. The demand for CF is expected to rise in coming years with an annual rate of approximately 10%; for example, a consumption of 89,000 t CF is predicted in the year of 2020. As a result, the amount of CF-wastes will increase as well. The sources of CF-wastes include extracted CF from recycled end-of-life carbon fibrereinforced plastic (CFRP) parts and production wastes from semi-finished products or preforms. However, there is no established recycling solution in the market to utilize the high potential of recycled CF (rCF), and thus to achieve a sustainable and resource efficient use. Already existing solutions (rCF injection molding parts and rCF nonwovens) achieve very low strength in CFRP (about 10-30% of the composite tensile strength of carbon filament yarn). Because of these reasons, the possibilities of a gentle production of rCF hybrid yarn are thoroughly investigated within the framework of the DFG project "Spinning of hybrid yarns from short carbon fiber for composites" at the Institute of Textile Machinery and High Performance Material Technology (ITM) of Technische Universität Dresden. For this purpose, first of all, the carding process is carried out on a laboratory carding machine, which is modified especially for the gentle processing of staple rCF by adjusting roller distances, speed and card clothings. The card webs with different rCF ratios mixed with polyamide 6 (PA6) staple fibers are further processed on a draw frame to produce rCF slivers. In order to carry out a careful processing of rCF, modifications have been made on this machine, notably the protection of electrical components and the adaptation of the drafting system due to the brittleness of rCF. The guiding elements, drafting rollers and load pressures are modified for this purpose. Using the developed technology, a hybrid draw frame sliver with very high fiber parallelism, homogeneous mixing and high uniformity could be achieved. Subsequently, different hybrid yarns consisting of rCF and PA6 staple fibres are developed for the first time on a roving frame and DREF-3000 friction spin machine. The results of uni-directional composites manufactured from flyer and DREF-3000 friction spun hybrid yarns exhibit about 80 % of the strength of thermoplastic unidirectional composites containing primary carbon filament yarns. The extensive experimental investigations carried out in the project enabled the establishment of a relationship and interaction between material parameter and process parameters of spinning (i.e. carding, drawing, flyer and friction spinning) with yarn and composite properties. A better understanding about the fibre to fibre cohesion of brittle CF fibre and its influence on the processability in entire yarn manufacturing steps to achieve high composite performance with staple rCF could be gathered. The developed rCF hybrid yarns will make a very high contribution to environmental protection and sustainability. Existing rCF can be reused purposefully in the material life cycle. As the recognition of the successful development of hybrid yarns from rCF for thermoplastic application, the ITM was awarded with the AVK-innovation prize 2016 and the “Deutscher Rohstoffeffizienz-Preis” 2016.

Projektbezogene Publikationen (Auswahl)

 
 

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