Coventive’s Quest for the Circular, Long Fibre Pellet
In the automotive industry lower weight means lower fuel consumption. One way to achieve lower weight is to replace heavy metal parts with lighter plastic ones, however, the replacement parts need to be made of materials offering similar structural performance. This is where composites come in.
In particular, long fibre reinforced thermoplastic composites (LFTs) offer increased strength and toughness; and could be considered the best choice for structural performance for injection mouldable thermoplastic parts. These qualities basically translate to lower weight for parts at equal structural performance, a valuable economic and environmental advantage.
Coventive have been working to develop first natural fibre, and now carbon fibre, LFT pellets. Their research progression, leading up to the practical implementation of their knowledge and processes for ECOBULK, was shared recently at the Long-Fibre Thermoplastics 2018 conference in Berlin. The work on recycled carbon fibre drew considerable interest from members of the automotive industry in the audience.
Coventive's LFT Journey
Coventive’s adventure into LFT’s started already with previous projects. Their original foray into this subject was more a feasibility study than anything else. With the project ECO-LFT, Coventive demonstrated their first ability to create a long fibre pellet that could be used for injection moulding. In a follow up project to develop a process for self-reinforced composites, PELTEC, they also by chance started experimenting with natural fibres. The experiment was eventually successful in delivering a pultrusion based process to create LFT pellets for which the material and moulded samples achieved all the technical specifications required by the manufacturers, except for one – price. The original recipe used continuous yarn fibre – which has a high added value and had a significant effect on the final pellet price. Coventive are working hard to replace the high value yarn with discontinuous, cheaper sources that will still maintain the same qualities. This project will conclude in the spring of next year, by which time they expect to be able to supply production samples to those interested.
For ECOBULK, targeting the automotive industry, the collaboration with Coventive was obvious. Cooperations like this clearly highlight the value of demonstration projects that can bring separate research developments together and integrate them into a practical, circular market application. The knowledge and experience gained by Coventive in the pultrusion process for LFT’s can now be implemented to specifically develop alternative carbon fibre LFT pellets using recycled and waste materials. This would achieve the required structural properties for diverse uses in car parts, at a competitive price, lower weight, and with full circular credentials.
Their initial studies have shown that it should be possible to create LFT pellets using selvedge waste (virgin carbon fibre trimmings – production waste) and pyrolised carbon fibres from waste composite materials (recycled). Using these sources, the fibres maintain slightly lower but similar properties, but offer a 35% – 50% reduction in price.
The supply of selvedge (virgin carbon fibre trimmings) for this purpose might pose problems at scale, although at the moment this is considered production waste and has no commercial value. The pyrolised carbon fibres however, can probably count on a readily available supply from waste composites recyclers once the value of them has been established.
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