Community Research and Development Information Service - CORDIS

Carbon fibres from biomass

Increasing demand for lightweight, high-performance composite materials is driving development in the carbon fibre (CF) industry. European researchers have obtained innovative low-cost precursors for CFs from renewable biomass to meet this growing need.
Carbon fibres from biomass
Around 80 % of CFs currently on the market use polyacrylonitrile (PAN) as the starting raw material, due to its superior properties compared to pitch-based CFs. However, CFs produced from PAN are expensive, limiting their application to aeronautics, the military and other sectors that require high performance materials and will therefore accept high material costs.

The EU-funded CARBOPREC project addressed this challenge, developing low-cost precursors for nanostructured CFs from renewable materials widely available in Europe. “Lignin and cellulose reinforced by carbon nanotubes is used to produce cost-effective CFs with medium performance for mass market applications like automobiles and wind turbine blades,” says Dr Célia Mercader researcher at CANOE, an R&D centre that specialises in the development of finished and semi-finished products in the field of composites and advanced materials.

Improved properties

Next to cellulose, lignin is the most abundant plant-derived polymer in the world and is found in almost all dry-land plant wall cells. Project partners obtained high purity lignin by using organic solvents to breakdown softwood, which was then spun in a mixture with thermoplastic polymers to give lignin-based fibres.

Researchers studied two white fibre processes for producing continuous fibres. The first involving a wet spinning approach for cellulose dissolved in phosphoric acid; the second using melt spinning by extrusion for the lignin. Investigation of the carbonisation process and the different functionalisation steps resulted in enhanced carbonisation yield and added value through the CFs developed in the targeted final applications.

CFs obtained from the cellulose precursor possessed the desired mechanical properties, making them suitable for the associated processes, which involved wet spinning of cellulose, and carbonisation. The team developed a new reactor, spin pump and spin pack for cellulose spinning that was installed at CANOE facilities, enabling the dissolution of the cellulose in phosphoric acid with carbon nanotubes.

Low-cost composites

One patent was filed for the carbonisation process and carbonised fabric used to manufacture demonstrator parts, including a wind turbine blade using CF from cellulose and thermoplastic resin. “This demonstrator exhibited good mechanical behaviour compared with the same part made of ex PAN carbon fibre,” comments Dr Mercader. Another key result for CARBOPREC was complete life cycle analysis modelling.

High purity cellulose- and lignin-based formulations enabled a homogenous dispersion of carbon nanotubes into the polymer. Optimisation of the carbonisation process increased the cellulose yield by up to 25 % and up to 40 % for lignin. Replacing the oxidation step with the plasma treatment step simplified the manufacturing process and improved the tensile strength of the CFs.

CARBOPREC enhanced commercial exploitation of R&D results, which can be applied to many areas including automotives, nano-composites, buildings, energy, bio-based materials and textiles. “It will help industry comply with new EU-regulations on vehicle emissions, by using low-cost composite parts to reduce the weight of cars, enabling longer blades to be manufactured for wind turbines that are both light and rigid, thereby capturing more energy,” Dr Mercader points out.

Keywords

CARBOPREC, carbon fibre, carbonisation, polyacrylonitrile (PAN), nanotubes
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