Innovative technology to produce carbon fiber from lignin on the way?

The Institute of Textile Chemistry and Chemical Fibers Denkendorf, specialised in research and the development of sustainable processes and materials from synthetic and natural polymers, is participating in a new European research project, together with renowned firms and research institutes from all over Europe, for the development of lignin-based carbon fiber for use in composite fiber materials. Known as the “LIBRE Project” (Lignin Based Carbon Fibers for Composites), the aim is to develop raw materials based on lignin derived from pulp and paper manufacture for highly stable carbon fiber composites.

To date, carbon fibers have been sourced from fossil-based polyacrylnitrile (PAN). Replacing PAN by biomass is an innovative way of meeting the increasing need for carbon fiber, in a resource friendly way. Lignin is ideal for this, since it occurs in large quantities as pulp, a waste product of the paper industry. In addition, the carbon content of lignin is high, thus fulfilling a prerequisite for the production of high quality carbon fiber.

Substituting the raw material is not the only aim of the research project: the so-called precursor fibers (fibers from the raw material) are transformed into carbon fibers in an energy-intensive and expensive thermal process. The new plan is to use microwaves and high-frequency radiation as efficient sources of heat. In this way, lignin-based carbon fibers could be produced significantly more competitively and cost-effectively.

A further aim of the project is to functionalise the surface of the fibers by means of a plasma. Plasma treatment is intended to replace liquid chemical treatment, providing a more energy- efficient and environmentally friendly alternative. Surface activation improves the adherence of the fibers to the composite fiber matrix. This results in fibers of high specific strengths, suitable for a variety of uses in lightweight construction.

In the joint project, the ITCF will be responsible for the precursor development, in cooperation with other partners. This will involve chemically functionalising the raw lignin in combination with further polymers, to develop a mechanically stable precursor fiber. For this, a cost-effective melt spin process developed by the ITCF will be used. In further steps the precursor fibers will be stabilised and carbonised in a continuous process at the ITCF. This is to take place in plants especially configured for the processing of lignin. Industrial partners will further process the carbon fibers thus obtained into prototypes for the automotive and wind energy industrial sectors.

This project is in the form of a private-public partnership called ’Bio-Based Industries’–is a joint undertaking between companies and research institutes, which aims to strengthen sustainable management in a bio-based industrial sector. The project will receive funding from the EU for a period of four years. 12 project partners are involved.(KL)

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