AS4D CHOP
Reinforced grade
CHOP = chopped / milled AS4D fiber for compounding
Use chopped or milled fiber to reinforce thermoset and thermoplastic compounds and to add conductivity or antistatic behaviour; there is no continuous load path, so laminate strength is not reached.
Values for the CHOP condition
Other AS4D grades and fills
AS4D is listed in 3 conditions; see the grade overview at AS4D.
Compare all 3 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Woven fabric AS4D/epoxy laminate | Choose the plain or satin woven prepreg laminate made from 12K tow for draping over curved tools and quasi-isotropic parts; ~55 % Vf yields 900 MPa and 70 GPa. | — | 900 | 1.3 | 88 Shore D |
Unidirectional AS4D/epoxy laminate, 60 % fiber volume | Use these cured aerospace-prepreg 0° values as design allowables for unidirectional primary structure: 2550 MPa, 148 GPa, 150 °C service and a Tg of 200 °C at 60 % fiber volume. | — | 2,550 | 1.7 | — |
CHOPThis page Chopped / milled AS4D fiber for compounding | Use chopped or milled fiber to reinforce thermoset and thermoplastic compounds and to add conductivity or antistatic behaviour; there is no continuous load path, so laminate strength is not reached. | — | 4,400 | 1.8 | — |
What is AS4D CHOP?
AS4D CHOP is AS4D in the CHOP grade — use chopped or milled fiber to reinforce thermoset and thermoplastic compounds and to add conductivity or antistatic behaviour; there is no continuous load path, so laminate strength is not reached. AS4D CHOP has a tensile strength of 4,400 MPa (638 ksi), stronger than 91% of composite grades. Elongation at break is 1.8% and the elastic modulus is 245 GPa (35.5 Msi). AS4D CHOP has a density of 1.79 g/cm³ (0.0647 lb/in³), heavier than 56% of composite grades.
Advantages
- Stiff — 245 GPa (35.5 Msi), better than 86% of composite grades
- High service temperature — 400°C (752 °F), better than 78% of composite grades
Limitations
- Difficult to machine — 15/100, worse than 84% of composite grades
- High embodied carbon — 30 kg CO₂/kg, worse than 80% of composite grades
AS4D CHOP properties
Typical room-temperature values for AS4D CHOP; 10 are specific to this condition. Other listed values are AS4D reference data and may not represent this condition. Bars are the position among composite grades.
Physical1
AS4D CHOP has a density of 1.79 g/cm³ (0.0647 lb/in³), heavier than 56% of composite grades.
Mechanical4
AS4D CHOP has a tensile strength of 4,400 MPa (638 ksi), stronger than 91% of composite grades. Elongation at break is 1.8% and the elastic modulus is 245 GPa (35.5 Msi).
Thermal6
AS4D CHOP is rated for continuous service to 400°C (752 °F). It conducts heat at 6.8 W/m·K (3.93 BTU/hr·ft·°F), better than 67% of composite grades. Thermal expansion is -0.6 µm/m·K (-0.333 µin/in·°F).
Electrical2
AS4D CHOP has an electrical resistivity of 1.5×10⁻⁵ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 65% of composite grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of AS4D CHOP takes about 400 MJ of energy and emits 30 kg of CO₂ — more than 77% of composite grades. Typical recycled content is 0%.
Manufacturability1
AS4D CHOP's machinability is poor (15/100, worse than 84% of composite grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AS4D CHOP
Is AS4D easy to machine?
Cured parts must be cut with diamond-coated or PCD tooling at high spindle speed and low feed, with dust extraction at the cutter. This limits delamination and fiber breakout and keeps conductive carbon dust out of the air and out of electrical equipment.
Can AS4D be welded?
Not weldable; join by adhesive bonding (abraded or peel-ply prepared surfaces) or by mechanical fasteners with bushings. Use titanium or A286 fasteners to avoid galvanic corrosion against the carbon.
Can AS4D be formed, bent or molded?
Cure prepreg in an autoclave or heated press at typically 177 °C / 0.6 MPa, or process by tow winding, RTM and automated fiber placement. Control bend radius and tension on dry fiber to avoid abrasion and fuzz build-up.
What surface finishes work on AS4D?
Sand and prime with epoxy primer, then apply a polyurethane topcoat. At interfaces with aluminum alloys add a glass-cloth or adhesive-film isolation layer, and surface-treat bond faces to raise joint strength.
AS4D chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Ccarbon content (carbonized PAN precursor) | 93.5 – 95 | 94 |
| Nresidual nitrogen | 3.5 – 6 | 5 |
| Osurface oxygen from electrochemical treatment | 0.3 – 1.5 | 0.8 |
| epoxy sizingGP sizing; 0 for UC (unsized) grade | 0.7 – 1.3 | 1 |
AS4D CHOP — frequently asked
What is AS4D CHOP used for?
AS4D CHOP is typically used for aircraft structures, rocket components and industrial composites. In short: improved-strength AS4 variant; aerospace prepreg workhorse; high-strain standard modulus.
What is the tensile strength of AS4D CHOP?
AS4D CHOP has a typical tensile strength of 4,400 MPa (638 ksi) — stronger than 91% of composite grades. Strength varies by condition: see the 3 listed tempers.
Is AS4D CHOP easy to machine?
Not especially — machinability is rated poor (15/100, worse than 84% of composite grades). Cured parts must be cut with diamond-coated or PCD tooling at high spindle speed and low feed, with dust extraction at the cutter. This limits delamination and fiber breakout and keeps conductive carbon dust out of the air and out of electrical equipment.
Can AS4D CHOP be welded?
Not weldable; join by adhesive bonding (abraded or peel-ply prepared surfaces) or by mechanical fasteners with bushings. Use titanium or A286 fasteners to avoid galvanic corrosion against the carbon.
What surface finishes work on AS4D CHOP?
Sand and prime with epoxy primer, then apply a polyurethane topcoat. At interfaces with aluminum alloys add a glass-cloth or adhesive-film isolation layer, and surface-treat bond faces to raise joint strength.
Can AS4D CHOP be formed, bent or molded?
Cure prepreg in an autoclave or heated press at typically 177 °C / 0.6 MPa, or process by tow winding, RTM and automated fiber placement. Control bend radius and tension on dry fiber to avoid abrasion and fuzz build-up.
What is the maximum service temperature of AS4D CHOP?
AS4D CHOP is rated for continuous use to about 400°C (752 °F), and briefly to 500°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- HexTow AS4D Carbon Fiber Product Data Sheet — Hexcel (2020)
- HexPly 8552 / 3501-6 Epoxy Prepreg Data Sheets — Hexcel (2020)
- ASM Handbook Vol.21: Composites — ASM International (2001)
- CMH-17 Composite Materials Handbook, Vol.2 Polymer Matrix Composites — SAE International (2012)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.