This paper reviews the research and development activities conducted over the past few decades on carbon fibers. The two most important precursors in the carbon fiber industry are polyacrylonitrile (PAN) and mesophase pitch (MP). The structure and composition of the precursor affect the properties of the resultant carbon fibers significantly. Although the essential processes for carbon fiber production are similar, different precursors require different processing conditions in order to achieve improved performance. The research efforts on process optimization are discussed in this review. The review also attempts to cover the research on other precursor materials developed mainly for the purpose of cost reduction.

https://www.mdpi.com/1996-1944/2/4/2369/pdf

Fabrication and Properties of Carbon Fibers

Carbon fiber is increasingly being utilized as a reinforcing material due to its high strength and high modulus, which is imparted into the properties of the final composite. A comprehensive review of the carbon fiber production process, from polymerization to fiber spinning and stabilization and carbonization, is provided. Relationships between carbon fiber microstructure and material performance is undertaken in order to assess the current status of the mechanical, thermal, and electrical properties of commercially available PAN and pitch based carbon fibers, as well as recently developed experimental carbon fibers. A discussion of next generation carbon fibers is also provided, with a discussion on carbon fiber derived from alternative precursor materials, as well as hierarchical carbon fiber composites.

Processing, structure, and properties of carbon fibers

The tensile modulus of carbon fibres is related to the preferred orientation of the layer planes, and it is easier to achieve high values with carbon fibres from mesophase pitch than from polyacrylonitrile (PAN). Tensile strength has been related to the flaw population, but with improved processing conditions, fundamental structural organisation is more important. Carbon fibres fail in both tension and compression by the rupture of layer planes in misoriented crystallites and the propagation of a crack beyond the critical size. PAN-based carbon fibres have a complex structure of interlinked layer planes which hinder crack propagation unless voids are present with extensive walls. In many cases crystalline walls are formed by catalytic graphitisation due to contaminant particles; it is these shells rather than the voids themselves which lead to premature failure. Mesophase-pitch-based carbon fibres crystallise so that the layer planes are arranged in sheets; this facilitates crack propagation and leads to lower strain-to-failure than for PAN-based fibres of similar modulus.

https://iopscience.iop.org/article/10.1088/0022-3727/20/3/007/pdf

Structure-property relationships in carbon fibres

Electron-microscope studies of structural heterogeneity in pan-based carbon fibres

Composites are, in general, a rapidly evolving and growing technical field with a very wide range of applications across the aerospace, defence, energy, medical and transport sectors as a result of...

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J.V. Sharp

Papers

Crystal shear limit to carbon fibre strength