Kevlar 49 CHOP
Reinforced grade
CHOP = chopped fiber (3–12 mm) for compounds and friction materials
Pick for thermoplastic/thermoset compounding, brake and gasket materials, and asbestos replacement.
Values for the CHOP condition
Other Kevlar 49 grades and fills
Kevlar 49 is listed in 5 conditions; see the grade overview at Kevlar 49.
Compare all 5 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Woven fabric / epoxy laminate, Vf ≈ 50 % | Design values for quasi-isotropic hand-layup or infused panels (hulls, radomes, impact skins). | — | 480 | 1.9 | — |
Kevlar 49 / carbon hybrid fabric laminate | Pick when carbon stiffness/compression must be combined with aramid impact and splinter containment. | — | 620 | 1.4 | 88 Shore D |
Epoxy prepreg (UD or woven, 120–180 °C cure) | Pick for autoclave/oven-cured aerospace and sporting-goods laminates needing repeatable fiber volume and resin content. | — | 1,350 | 1.8 | 86 Shore D |
Unidirectional Kevlar 49 / epoxy laminate, Vf ≈ 60 % | Design values for 0° dominated tension-critical structures (pressure vessels, tension members). | — | 1,380 | 1.8 | — |
CHOPThis page Chopped fiber (3–12 mm) for compounds and friction materials | Pick for thermoplastic/thermoset compounding, brake and gasket materials, and asbestos replacement. | — | 3,000 | 2.4 | — |
What is Kevlar 49 CHOP?
Kevlar 49 CHOP is Kevlar 49 in the CHOP grade — pick for thermoplastic/thermoset compounding, brake and gasket materials, and asbestos replacement. Kevlar 49 CHOP has a tensile strength of 3,000 MPa (435 ksi), stronger than 81% of composite grades. Elongation at break is 2.4% and the elastic modulus is 112 GPa (16.2 Msi). Kevlar 49 CHOP has a density of 1.44 g/cm³ (0.052 lb/in³), lighter than 61% of composite grades. Its glass-transition temperature is 360°C (680 °F).
Limitations
- Degrades in UV without stabilisers — 20/100, worse than 94% of composite grades
- Poor heat conductor — 0.04 W/m·K (0.0231 BTU/hr·ft·°F), worse than 91% of composite grades
- Difficult to machine — 20/100, worse than 77% of composite grades
Kevlar 49 CHOP properties
Typical room-temperature values for Kevlar 49 CHOP; 11 are specific to this condition. Other listed values are Kevlar 49 reference data and may not represent this condition. Bars are the position among composite grades.
Physical3
Kevlar 49 CHOP has a density of 1.44 g/cm³ (0.052 lb/in³), lighter than 61% of composite grades. Its glass-transition temperature is 360°C (680 °F).
Mechanical5
Kevlar 49 CHOP has a tensile strength of 3,000 MPa (435 ksi), stronger than 81% of composite grades. Elongation at break is 2.4% and the elastic modulus is 112 GPa (16.2 Msi).
Thermal8
Kevlar 49 CHOP is rated for continuous service to 180°C (356 °F). It conducts heat at 0.04 W/m·K (0.0231 BTU/hr·ft·°F), worse than 91% of composite grades. Thermal expansion is -2 µm/m·K (-1.11 µin/in·°F).
Electrical4
Kevlar 49 CHOP has an electrical resistivity of 1×10¹³ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (70/100), worse than 64% of composite grades. UV resistance is poor.
Sustainability3
Producing a kilogram of Kevlar 49 CHOP takes about 280 MJ of energy and emits 17 kg of CO₂ — more than 63% of composite grades. Typical recycled content is 0%.
Manufacturability1
Kevlar 49 CHOP's machinability is poor (20/100, worse than 77% of composite grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Kevlar 49 CHOP
Is Kevlar 49 easy to machine?
Cut with serrated/shear scissors, hot knife or abrasive waterjet; drilling needs brad-point or dagger drills with backing to stop fuzzing and delamination — carbide tools dull quickly.
Can Kevlar 49 be welded?
Not weldable; join by adhesive bonding, co-cured resin joints or mechanical fasteners with bushings to avoid fiber crushing.
Can Kevlar 49 be formed, bent or molded?
Excellent drape for hand layup, RTM/infusion, braiding and filament winding; dry the fiber (~4 h at 100–120 °C) before impregnation and use low-viscosity resin plus vacuum to fully wet the yarns.
What surface finishes work on Kevlar 49?
Seal all cut edges with resin to block moisture wicking; sanding leaves fuzz, so use peel-ply for bond surfaces and pigmented/UV-blocking topcoats or gelcoat for outdoor exposure.
Kevlar 49 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 |
|---|---|---|
| p-phenylenediamine (PPD) monomer unitas-polymerized mole basis | ≈ 45 | 45 |
| terephthaloyl chloride (TCl) monomer unias-polymerized mole basis | ≈ 55 | 55 |
| surface finish / sizingform-dependent (weaving, epoxy-compatible or none) | 0 – 1 | 0.3 |
| poly(p-phenylene terephthalamide) (PPTA)condensation polymer of p-phenylenediamine and terephthaloyl chloride; ~0.1–1 % surface finish/sizing depending on form | balance | — |
Kevlar 49 CHOP — frequently asked
What is Kevlar 49 CHOP used for?
Kevlar 49 CHOP is typically used for aerospace composite panels, boat hulls, pressure vessels, sporting goods and armor laminates. In short: standard structural aramid fiber; best impact-to-weight laminate; poor compressive strength.
What is the tensile strength of Kevlar 49 CHOP?
Kevlar 49 CHOP has a typical tensile strength of 3,000 MPa (435 ksi) — stronger than 81% of composite grades. Strength varies by condition: see the 5 listed tempers.
Is Kevlar 49 CHOP easy to machine?
Not especially — machinability is rated poor (20/100, worse than 77% of composite grades). Cut with serrated/shear scissors, hot knife or abrasive waterjet; drilling needs brad-point or dagger drills with backing to stop fuzzing and delamination — carbide tools dull quickly.
Can Kevlar 49 CHOP be welded?
Not weldable; join by adhesive bonding, co-cured resin joints or mechanical fasteners with bushings to avoid fiber crushing.
What surface finishes work on Kevlar 49 CHOP?
Seal all cut edges with resin to block moisture wicking; sanding leaves fuzz, so use peel-ply for bond surfaces and pigmented/UV-blocking topcoats or gelcoat for outdoor exposure.
Can Kevlar 49 CHOP be formed, bent or molded?
Excellent drape for hand layup, RTM/infusion, braiding and filament winding; dry the fiber (~4 h at 100–120 °C) before impregnation and use low-viscosity resin plus vacuum to fully wet the yarns.
What is the maximum service temperature of Kevlar 49 CHOP?
Kevlar 49 CHOP is rated for continuous use to about 180°C (356 °F), and briefly to 250°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Kevlar Aramid Fiber Technical Guide (Kevlar 49 properties) — DuPont (2017)
- ASM Handbook Vol. 21: Composites — ASM International (2001)
- CMH-17 (MIL-HDBK-17) Composite Materials Handbook, Vol. 3 Polymer Matrix Composites — SAE International / CMH-17 (2012)
- ASTM D7269 – Tensile Testing of Aramid Yarns — ASTM (2017)
- CES/Granta EduPack eco and mechanical data, aramid fiber & KFRP records — Ansys Granta (2023)
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.