Lignin – an alternative precursor for sustainable and cost-effective automotive carbon fiber

Lightweight design is an essential part of the overall Volkswagen strategy for reducing the CO2 emission. The use of carbon fiber reinforced polymers (CFRP) offers an enormous lightweight potential in comparison to aluminum, enabling a weight reduction, if a load-adapted (unidirectional) CFRP-design is used, of up to 60% in automobile parts without a degradation of the functionalities. Today, the use of CFRP is limited in mass series applications of the automotive industry by the cost of the conventional carbon fiber precursor Poly-Acrylic-Nitrile (PAN). Fifty percent of the cost of a conventional carbon fiber already belongs to the cost of the PAN precursor. The analysis of lignin as an alternative precursor shows clearly a significant reduction in the cost of CFRP and reduction of CO2 emission during carbon fiber production. This fact is essential to make carbon fibers ready for a mainstream use within the automotive industry. Key aspects are: the examination and quantification of lignin as an alternative precursor, the optimization of the manufacturing processes, the characterization and quantification of the properties of the novel carbon fibers within an established material pre-validation process and a final economic efficiency and sustainability analysis. Furthermore, the process ability and demonstrators as well as the suitability for high volume production of the developed processes are main issues for successful implementation in future lightweight vehicle concepts.