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Composites recycling still in its infancy: Report

22 Jul '16

3 min read

Composites recycling is still in its infancy. Whilst the options for recycling of glass fibre composites are limited by the low value of glass fibre, the high value of carbon fibre has resulted in a number of recycling companies starting up around the world, according to a report by Composites UK along with the Universities of Nottingham, Manchester and Birmingham.

The report on composites recycling titled 'Composites Recycling – Where are we now?' was launched earlier this month to coincide with its circular economy event at ELG Carbon Fibre on 7th July.

According to the report, recovering high grade carbon fibre only solves part of the problem and finding markets of sufficient size capable of using recovered carbon fibre is a major challenge where research is being focused.

The key issue is that recovered carbon fibre is in a physical form unlike any virgin carbon fibre material and so this limits the markets into which it can be sold. In applications where recovered carbon fibre is used as a reinforcement in polymer composites, achieving high fibre volume fractions is a key goal and this requires the development of viable techniques for alignment of the recovered fibres.

Polymer composites with easily achievable fibre volume fractions of about 30 per cent only compete with other lower value materials such as glass fibre composites or aluminium and producing recovered carbon fibre cheaply enough to compete with these materials is a challenge. Carbon fibre volume fractions of up to 60 per cent are needed to make composites that compete only with high value virgin carbon fibre composites and near unidirectional fibre alignment is needed to achieve these fibre volume fractions.

Current fibre recovery technology only yields energy from the polymer and in the future solvolysis and other chemical processes are needed to recover valuable chemicals from the polymer matrix. While a number of these processes have been demonstrated at laboratory scale there are challenges to scale these up to be viable commercially.

There is also scope for improving pyrolysis processes to minimise fibre property degradation. Some research is being undertaken to develop epoxy and other resins that are more easily recyclable. However, it will be many years before these materials are used in significant quantities and enter the recycling chain. So current recycling technologies will be needed for many years to come.

The other challenge is one of composite waste availability. Most of the products into which carbon fibre is used have a long service life and so the end of life components will not be available for recycling for many years. So it will be some time before the larger volumes of carbon fibre currently being produced become available for recycling and so the growth of the recycling sector will lag significantly behind the current growth in the carbon fibre manufacturing.

For GRP, product specific development is needed to incorporate regrind as a reinforcing filler, e.g. in infrastructure products. The main need is to develop appropriate business models, integrating with existing waste management supply chains and with associated capital investment, to enable commercialisation of what is technically proven. There is also a need to develop the supply chain in UK for co-processing GRP waste in cement kilns, the report said. (SH)

Fibre2Fashion News Desk – India