Single Carbon Fibres: Structure from X-ray Diffraction and Nanomechanical Properties
High performance carbon fibres are mainly used as reinforcement in fibre-reinforced structural components in aerospace-, automotive-, sports-, and energy applications. For example, many of the lightweight and stiff structural parts of bicycles, sport cars or wind turbine blades are nowadays made of carbon fibre reinforced plastics (CFRP), and the demand for such materials is continuously increasing. The dominant part (more than 90%) of carbon fibres are produced from polyacrylonitrile (PAN) precursor fibres with intermediate moduli of a few 100 GPa, but very high tensile strength up to 8 GPa. The second important class are fibres produced from mesophase pitches (MPP), leading to fibres with extremely high moduli (almost 1000 GPa) as well as good thermal and electrical conductivity. Together with their low weight, chemical resistance, biocompatibility, temperature tolerance and low thermal expansion, carbon fibres may only be beaten by other carbons such as carbon nanotubes (chapter 3) or graphene (chapter 4) as reinforcing materials. Although being much cheaper than those “modern” carbon nanomaterials, still carbon fibres are relatively expensive as compared to, e.g., glass fibres. Nonetheless, the world-wide carbon fibre production is steadily increasing and is expected to double from 68.000 tons in 2015 to 130.000 tons in 2020 (Holmes 2013). This demonstrates that carbon fibres are - and will further remain - the absolutely dominating carbon nanomaterials for light weight structural parts.