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Carbon fibres at Courtaulds. Click on the green arrow to return to the previous page

Carbon fibres were made by Courtaulds from the mid 1960s until production ceased in 1991.Courtaulds was taken over by Akzo-Nobel in 2000. Courtauld's carbon fibre was made from Courtelle precursor fibre which was polyacrylonitrile (PAN) and used in textile applications. This white fibre was taken through a series of furnaces and stretching processes to carbonize it and yield high strength carbon fibre. In the 1980's the main market for Courtauld's carbon fibre (Grafil) was in aerospace and sport goods. One of the difficulties in the precursor was that impurities could enter into the dope from which the original PAN fibres were spun and these lead to localised points of weakness in the carbon fibre product. To reduce these stringent filtering was used to exclude impurities. Different precursors can be used to make modern carbon fibres and if a highly crenulated precursor with a cog wheel cross section is used, the resulting carbonized fibre possesses a large surface area and is very effective in gaseous absorption.

My involvement with carbon fibre research at Courtaulds was to provide an X-ray diffraction service to monitor the structural parameters of the carbon fibre to optimise the production process. This involved measuring the crystallite size, inter-planar atomic (d) spacing and orientation of the crystallites relative to the fibre axis. These parameters could only be measured by X-ray diffraction (XRD). The carbon fibres were very fine and easily snagged on any rough skin on your fingers so it was necessary to moisten the fibres with glycerine to facilitate handling. An internal X-ray calibration material was added to a bundle of fibres before it was analysed by XRD. The gelatine based silver halide emulsion from developed glass photographic plates (used to collect images from an old transmission electron microscope) was found ideal and a small piece of the blackened gelatine was incorporated into the carbon fibres. This calibration standard generated sharp peaks because of the large crystallite size of the silver halide crystals and gave not only an internal calibration of d spacing on a chart recorder output but also a measure of instrumental line broadening.