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 chemical fiber fabric of high specific strengths, suitable for a variety of uses in lightweight construction.