From Boeing’s waste to new wind blades…
Some major new high volume markets for nonwovens based on recycled carbon fibre are being opened up with the establishment of the first fully-integrated supply chain for recycling aerospace waste.
UK-headquartered ELG Carbon Fibre (ECF) has recently announced a partnership with Boeing under which it will collect excess carbon fibre from eleven of the aerospace giant’s manufacturing sites to turn them into new products.
ECF has now established the recycling of carbon fibre waste at an industrial scale of above 1,000 tons per year, based on a patented furnace process called ‘continuous pyrolysis’. This involves the thermal removal of resins in a controlled environment at temperatures in the range of 400-650°C.
Under its Carbiso and Carbiso M brands, it is manufacturing nonwoven mats made from the 100% recycled carbon fibre, and those in blends with thermoplastic fibres. These products have a relatively high loft, good drape and a consistent fibre areal weight. As the nonwoven reinforcements for new composite products, they can be used in processes including prepreg compression moulding, liquid compression moulding and vacuum infusion and their very regular surface enables high quality finishes to be achieved.
In hybrid products, recycled carbon fibres can be further combined with virgin carbon fibres to produce lightweight structures that otherwise would not be economic. Typically, such structures comprise 10-20% virgin carbon fibre.
In a further development, Japan’s Mitsubishi Corporation is now poised to acquire a 25% stake in ECF, providing the UK company with access to an established global network of sales and marketing channels in order to enhance business development and reliable supply.
While Japan is the global leader in carbon fibre technology, producing almost 70% of the world’s supply, its recycling technologies have not yet caught up, and this new partnership addresses an important barrier to the mass adoption of recycled carbon products in a number of major industries.
One high volume market in which ECF now anticipates success is in the supply IC Matrix or JEDEC carrier trays employed in the electronics industry. These are specified to meet established standards for the safe handling, transport and storage of integrated circuits, modules and other components.
The single order quantities required by this industry of anything up to 100 tons have been impossible to meet in the past, yet composites based on recycled carbon fibre, or hybrids, are perfectly able to meet the specifications required.
“Security of supply is extremely important when considering using these materials in long-term projects,” says ECF managing director Frazer Barnes. “The agreements with Boeing and Mitsubishi give us the ability to provide that assurance, which in turn gives our customers the confidence to use recycled materials.”
Further opportunities exist in the wind energy sector, where the strength of carbon fibres is now becoming necessary to supplement glass fibre-based blades as they become increasingly longer – the latest in the pipeline from Siemens Gamesa, for example, will be a staggering 94 metres in length, equivalent to the length of a football pitch.
A number of nonwovens manufacturers are already involved in the wind power sector, including Lantor of the Netherlands, with its patented Coremat and Soric honeycomb core-structured polyester nonwovens. For nacelle housings and spinners, these help to rapidly build up the thickness of laminates and in wind blades, they ensure good flow of the resin during composites production.
Lantor’s products also benefit from the Expancel Microsphere technology of Nouryon (formerly AkzoNobel Specialty Chemicals) which serve as both blowing agents and lightweight fillers. The microspheres consist of a thermoplastic shell encapsulating a gas and when heat is added they expand dramatically – up to 60 times their original volume.
Several other companies also produce nonwovens using short carbon fibres, although in many cases these are still based on virgin fibres and come from offcuts, weaving selvedge etc. Such nonwovens can be made by the air laying, carding and needlepunching or wet-laid processes.
Nonwoven technology suppliers and INDEX™20 exhibitors including Autefa, Dilo, Tatham and Ying Yang all manufacture dedicated needlepunching lines and other equipment for the recycling of carbon composite waste.