HexTow AS4, IM7, IM8 — aerospace-grade PAN-based carbon fiber

Country: · Model: HexTow AS4, IM7, IM8

HexTow AS4, IM7 and IM8 are continuous polyacrylonitrile-based carbon fibers, untwisted, with surface treatment. Tensile strength rises from 4501 MPa in AS4 to 6170 MPa in IM8, and modulus from 231 to 304 GPa.

Type: continuous PAN fiber with surface treatment, untwisted
AS4: high strength, 3K/6K/12K; strength 4501 MPa, modulus 231 GPa, elongation 1.8 %, density 1.79 g/cm³
IM7: intermediate modulus, 6K/12K; 5670 MPa, 276 GPa, 1.8 %, 1.78 g/cm³; filament diameter 5.2 µm
IM8: intermediate modulus, 12K; 6170 MPa, 304 GPa, 1.9 %, 1.79 g/cm³; filament 5.1 µm

Request a quote All specifications

Technical specifications

Type	continuous PAN fiber with surface treatment, untwisted
AS4	high strength, 3K/6K/12K; strength 4501 MPa, modulus 231 GPa, elongation 1.8 %, density 1.79 g/cm³
IM7	intermediate modulus, 6K/12K; 5670 MPa, 276 GPa, 1.8 %, 1.78 g/cm³; filament diameter 5.2 µm
IM8	intermediate modulus, 12K; 6170 MPa, 304 GPa, 1.9 %, 1.79 g/cm³; filament 5.1 µm
Carbon content	95 %
Qualification	AS4-GP 3k/12k, AS4 12k, IM7-G 12K — per NMS 818 (NCAMP); produced to specification HS-CP-5000
Processing	weaving, prepregs, filament winding, braiding, pultrusion

Specifications are taken from the manufacturer’s technical documentation. Updated 11/06/2026.

Description

AS4 is a high-strength fiber with high elongation in 3K, 6K and 12K tows, density 1.79 g/cm³, elongation at break 1.8 %. IM7 is an intermediate modulus fiber in 6K and 12K tows, with a strength of 5670 MPa, modulus of 276 GPa, filament diameter of 5.2 µm and carbon content of 95 %. IM8 develops IM7 further and gives 6170 MPa and 304 GPa in a 12K tow, with a 5.1 µm filament; it is produced to specification HS-CP-5000. The AS4-GP 3k, AS4-GP 12k, AS4 12k and IM7-G 12K versions are qualified to NMS 818 of the NCAMP program, so the customer can refer to an industry standard without their own specification. The sizing improves interlaminar strength and processability. The fiber goes to weaving, prepregs, filament winding, braiding and pultrusion, and it is the basis of most HexPly prepregs. For IM8 in 8552 prepreg the TDS gives unidirectional laminate properties at a fiber volume fraction of 60 %. The batch is accompanied by a certificate of analysis, and supply is on bobbins.

How to choose

If strength and elongation are needed at moderate stiffness, AS4 is taken, and for stiffer and lighter parts IM7; when the margin in strength and modulus must be even greater, switch to IM8. A ready prepreg on the 8552 matrix already contains these fibers, and for repair with a cure at 130 °C and for 204 °C there are M20 and M65.