Scientists mix carbon fibre & hemp for lighter auto parts

January 09, 2015 - Germany

Researchers at the Fraunhofer Institute for Wood Research have found that blending carbon fibres and hemp, cotton, or wood fibres, offer extremely light yet very sturdy components for automobile bodies.

“Variants derived from hemp, flax, cotton and wood are about as affordable as glass fibers, and moreover have a lower density than the pendants made of glass or carbon fibres,” Fraunhofer says.

However, according to Fraunhofer, independently the durability and stability of these natural fibres, does not reach that of carbon fibres.

“Depending on the application, we are therefore combining carbon with various bio-based textile fibres,” explains Dr Ing Hans-Josef Endres, head of the Application Center for Wood Fiber Research.

The fibres typically exist as fabrics that are placed on each other accordingly and are embedded by the plastic matrix.

“We use carbon fibres in those areas where the part undergoes intense mechanical stress, while in other areas, it is natural fibres,” he informs.

He adds, “This way, we can leverage the strengths of the respective fibres and get rid of the disadvantages to a great extent.”

The outcome is that parts are cost-effective, have a very high degree of durability, possess excellent acoustic properties and are substantially more ecological than pure carbon components.

Typically, the surface of the natural fibres are treated a process also called ‘sizing the surface of the fibre’, so that they can be run easily through the equipment, and can be processed as well in to fabrics.

While this is important for textile production, it is usually counterproductive, however, if composite materials have to be processed.

“This is why, from a materials engineering perspective, we optimise the surfaces of the fibres,” says Endres.

Specialized surface treatments or coatings are intended to ensure that the fibres can be combined and interact in the best possible way with the matrix or the plastic mass.

“By ensuring that the fibres bond to the matrix optimally, we can increase the durability of the materials by up to 50 per cent,” Endres explains. (AR)