Coal the heat and pressure of deep burial causes the loss of water, methane and carbon dioxide and an increase in the proportion of carbon. Thus first lignite (also called "brown coal"), then sub-bituminous coal, bituminous coal, and lastly anthracite (also called "hard coal" or "black coal") may be formed. The wide, shallow seas of the Carboniferous Period provided ideal conditions for coal formation, although coal is known from most geological periods. The exception is the coal gap in the Permian–Triassic extinction event, where coal is rare. Coal is known from Precambrian strata, which predate land plants—this coal is presumed to
Pitch-based carbon fiber the automotive and sports industries, but the cheaper PAN based carbon fibers provide a high enough strength for these applications. Pitch-based carbon fiber Carbon fiber is often time produced using two main methods: through the use of Polyacrylonitrile (PAN) and from pitch. Pitch is a viscoelastic material that is composed of aromatic hydrocarbons. Pitch is produced via the distillation of carbon-based materials, such as plants, crude oil, and coal. Pitch is isotropic, but can be made anisotropic through the use of heat treatments. However, the most important in carbon fiber production is mesophase pitch due to the ability to melt