Composites are often perceived as being advanced materials, as many were developed for aerospace, military or formula one racing. This association is also partly based on the distinctive herringbone pattern and appearance of composites such as carbon fibre, which have become part of the modern family of luxury materials. But can a composite made up of carrot fibres still be considered an advanced material?
More and more plants are becoming valuable sources of material innovation: starch from corn and potato skins, hemp fibres, castor oil, bark and algae are some of the plant products that are driving development of new materials. However, the applications of these materials are no longer being perceived as rural, and are instead leading to radical new innovations in the world of advanced composites. The main innovation here is the use of a rapidly renewable source of fibres from carrots and other root vegetables in comparison to oil, which is used to produce carbon fibres. However, around 20 per cent oil is still needed in what is branded as Curran® to complement the 80 per cent carrot fibres.
Dr David Hepworth and Dr Eric Whale produced Curran® to utilize nanofibres extracted from root vegetables. The process involves mechanically breaking down carrots into tiny particles to form a slurry. The fibres are then extracted and formed into various states from which parts can be moulded, or coatings of Curran® can be applied or mixed with other resins.
Image: The Reactor™ fishing rod, made from Curran® and carbon fibre
•Low temperature production
•Based on a renewable resource
•High strength-to-weight ratio
•Outstanding toughness
•Outstanding stiffness
•Compelling consumer story
Sources
At present, the technology is limited to UK-based CelluComp.
Cost
According to CelluComp, the main costs are in the process used to produce the composite itself, rather than the actual fibres, which in relation to carbon or glass fibres are still very low cost.
Sustainability issues
Curran® is produced from the carrot waste discarded in the food industry, therefore it does not compete for land with crops for food.
Production
Curran® in its primary state comes out as a paste (similar to mashed potatoes). The paste has 93% water and 7% cellulose fibres and can be mixed with different polymers. Because Curran® is in a semi-liquid state it is very easy to use the material by mixing it with paints, coatings and resins, and it is compatible with a multitude of conventional resins, such as epoxy, polyurethane and polyester. It is also available as a powder, as sheets, and as a loose matting.
Typical applications
One of the applications that CelluComp is exploring for Curran® is as an additive for paints and coatings, where it would work as a thickener and also enhance the mechanical properties. Shredded Curran® sheets can be used as a loose matting to put into 3D moulds and pieces can be made using vacuum moulding or resin transfer moulding. In paste form, Curran® can be dried into thin sheets and then used as laminates for the construction of solid panels, for layers in skis or skate boards, or on the outside of core materials such as foam. These sheets are 85% cellulose fibre and 15% resin, so a very high percentage of randomly-orientated fibre is in the final product and the mechanical properties are impressive.
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–High strength-to-weight-ratio –Tough –Good stiffness –Sustainable |
–Currently only available from limited suppliers |