Rayon-based carbon fibres have a more
isotropic structure than similarly heat-treated polyacrylonitrile (
PAN)- or
mesophase pitch (MPP)-based carbon fibres.
Their
Young's modulus values are therefore drastically lower
(
; tensile strength

).
Rayon-based carbon fibres can be transformed into anisotropic carbon fibres with high
strength and
Young's modulus values by hot-stretching treatment at temperatures of approximately

.