Carbon & Epoxy

Carbon

Carbon fibre is produced by the controlled oxidation, carbonisation and graphitisation of carbon-rich organic precursors which are already in fibre form. The most common precursor is polyacrylonitrile (PAN), because it gives the best carbon fibre properties, but fibres can also be made from pitch or cellulose.

Variation of the graphitisation process produces either high strength fibres (@ ~2,600°C) or high modulus fibres (@ ~3,000°C) with other types in between. Once formed, the carbon fibre has a surface treatment applied to improve matrix bonding and chemical sizing, which serves to protect it during handling. Carbon fibres are usually grouped according to the modulus band in which their properties fall. These bands are commonly referred to as: high strength (HS), intermediate modulus (IM), high modulus (HM) and ultra-high modulus (UHM). The filament diameter of most types is about 5–7µm. Carbon fibre has the highest specific stiffness of any commercially available fibre, very high strength in both tension and compression and a high resistance to corrosion, creep and fatigue.

Epoxy

The large family of epoxy resins represent some of the highest performance resins of those available at this time. Epoxies generally outperform most other resin types in terms of mechanical properties and resistance to environmental degradation, which leads to their almost exclusive use in aircraft components.

As a laminating resin, their increased adhesive properties and resistance to water degradation make these resins ideal for use in applications such as boat building. Here, epoxies are widely used as a primary construction material for high-performance boats or as a secondary application to sheath a hull or replace water-degraded polyester resins and gel coats. The term ‘epoxy’ refers to a chemical group consisting of an oxygen atom bonded to two carbon atoms that are already bonded in some way.