Serendipity in Carbon Fibres: Interfaces and Interphases in Composites

Abstract

The development of high strength and high modulus carbon fibres from polyacrylonitrile is discussed. The serendipity of the availability of Courtelle acrylic fibres is considered. William Watt and colleagues at the Royal Aircraft Establishment (RAE) in Farnborough discovered in the mid 1960’s the technique for converting polyacrylonitrile (PAN) into high strength carbon fibres (CF), which heralded the field of Composites. From a historical perspective it was serendipitous because “Black Orlon” was known and Akio Shindo, in Japan, had reported that ‘high strength’ CF could be obtained from thermally treated PAN textile fibre. Courtaulds in the UK had developed the aqueous spun copolymer textile fibre in which the internal plasticiser segments promoted drawing while the dye site segments initiated ladder polymer formation- the nuclei for graphitisation. Watt’s interest in establishing the surface functionality of electrolytically oxidised high strength CF inspired the author’s interest in interfacial chemistry and micromechanics. The development of understanding of interfacial micromechanics of carbon fibre composites is described. It is also shown how controlling the interphase structure is critical in optimising mechanical performance of these composites for structural applications. The use of conformal functional plasma polymer coatings to replace the traditional oxidation and sizing stages is considered.