With new emission standards in Europe and North America, automotive manufactures are looking for new and innovative ways to make vehicles both lighter and stronger. Advanced composite materials like carbon fibre are being used increasingly to replace standard materials like steel and aluminium in modern construction.
While composite materials are lighter and stronger, they are as you would expect more expensive and sometimes more tricky to fabricate, where cheaper alternative like glass fibre, can reduce the costs but tend to be heavier and not as strong, although thanks to new research this might be changing.
Researchers at the Application Centre for Wood Fibre Research of the Fraunhofer Institute for Wood Research, the Wilhelm-Klauditz-Institut WKI in Braunschweig are looking at natural alternatives to Carbon Fibre Reinforced Plastics in natural fibre composites made from flax, hemp, cotton and wood.
Variants derived from these natural materials are as affordable as glass fibres and have a lower density, they also burn cleanly without residues at the end of their life cycle. However these materials are nowhere near as strong or durable as carbon composites.
To get around the problem of cost, the research team started to combine carbon fibres with different bio based textile fibres, supplementing as opposed to replacing completely. The idea would be to put carbon fibres in areas where the part undergoes intense mechanical stress where in other areas you could use natural fibres, utilising the strengths and properties in different ways.
The researchers say by leveraging the materials in this way makes the composite parts more cost-effective, have a very high degree of durability, possess excellent acoustic properties and are substantially more ecological than pure carbon components.
As you would expect creating these hybrid composite materials is not a straightforward process. The botanical fibres need to be processed differently to interact with the different types of composite resins, ensuring that the fibres have been processed correctly however, can increase the durability of the materials by up to 50%. Such treatments are routine in carbon fibre production but when it comes to the use textile fibres for reinforcement, the researchers are treading on virgin territory.
As well as creating new hybrid materials, the researchers are also studying how the processing processes for these new materials can be implemented on an industrial scale. By the same token, they also have an eye on the proper disposal of hybrid materials. Because when it comes to recycling, fibre composite materials are a proverbial “tough nut to crack.” For instance, how can expensive carbon fibres be extracted from the matrix and recovered? With the hybrid materials they’ve engineered, the scientists are already considering in advance how these can be reprocessed or how, at least, individual materials components can be recovered for a new use or application. In doing so, they are pursuing various physical, thermal, and chemical approaches, de-pending on the material composition.