November saw some interesting developments in the USA in the use of alternative precursors to polyacrylonitrile (PAN) for the manufacture of carbon fibre.
A process for producing carbon fibre suitable for the production of ablative rocket nozzles from rayon is the subject of a recently awarded patent.
Developed by Professor William Kaukler of the University of Alabama in Huntsville (UAH), USA, the ionic liquid-based process could be of interest to the US National Aeronautics and Space Administration (NASA), which has a dwindling stockpile of cellulose rayon fibre that dates back to the late 1990s when its manufacture in the USA ceased.
North American Rayon Corp (NARC) ceased rayon production in the USA after Environmental Protection Agency regulations (EPA) covering the hazardous wastes generated by the process rendered it financially unviable.
While stronger, the thermal conductivity of PAN-based carbon fibre is too high for the manufacture of rocket nozzles. The thermal conductivity of rayon-based fibres is considerably lower. MATECH of Westlake Village, California, USA, is currently working with UAH to scale-up this process as part of a phase-1 Small Business Innovation Research (SBIR) programme.
Meanwhile, A US$1.6-million project to develop cost-effective and environmentally friendly methods for turning coal-derived pitch into carbon fibres is getting underway at the University of Utah in Salt Lake City, USA.
University of Utah Chemical Engineering Professor Eric Eddings, who is leading the research, says: “There is an abundance of coal and we would like to find an alternative use for it. It is a huge natural resource in the USA, and we have a whole coal-mining community that is desperate for a new direction.
“If we can find an economical way to use coal to produce carbon fibres and have enough useful products so there can be a market for it, then they have that new direction. And it is more carbon-friendly than just burning coal in a power plant.”