carbon fibres type HT

Carbon fibres type HT are carbon fibres with values of Young's modulus between $150$ and $275$ to $300 GPa$ . The term HT, referring to high tensile strength, was early applied because fibres of this type display the highest tensile strengths.

Note:

The disposition of boundaries between the fibre types is somewhat arbitrary. For carbon fibres type HT, the values of the strength-to-stiffness ratio are typically larger than $1.5 × 10 −2$ . The tensile strength of carbon fibres is flaw-controlled, however, and therefore the measured values increase strongly as the diameter of the filaments is decreased.

Source:

PAC, 1995, 67, 473 (Recommended terminology for the description of carbon as a solid (IUPAC Recommendations 1995)) on page 481