Kevlar 149
Kevlar 149 is the ultra-high-modulus para-aramid variant (density 1.47 g/cm³, tensile strength 3400 MPa, elastic modulus 175 GPa, elongation 1.5 %) with the lowest moisture absorption of the family.
Reference datasheet — Kevlar 149 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Kevlar 149 grades and fills
Kevlar 149 is supplied in 2 conditions, soft to hard.
Compare all 2 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Woven Kevlar 149 fabric / epoxy laminate | Pick for panels, radomes and impact-tolerant shells needing balanced biaxial stiffness and high damage tolerance. | 620 | 1.8 | ||
Unidirectional Kevlar 149 / epoxy laminate | Pick when maximum specific tensile stiffness along one axis is required and compression loads are low. | 1,750 | 1.6 |
Supply forms, finishes and certifications
Ways Kevlar 149 is supplied — form, process route, surface or paperwork — without a datasheet of their own. A reinforced fill changes stiffness and elongation; the branded products above carry the filled values.
| Option | What it is | Type |
|---|---|---|
ROVING | Roving / tow for filament winding and pultrusion | Supply form |
YARNDefault | Continuous filament yarn | Supply form |
FABRIC | Woven fabric | Reinforcement |
What is Kevlar 149?
Kevlar 149 is the ultra-high-modulus para-aramid variant (density 1.47 g/cm³, tensile strength 3400 MPa, elastic modulus 175 GPa, elongation 1.5 %) with the lowest moisture absorption of the family. It is used where maximum stiffness and dimensional stability are required from an aramid reinforcement, supplied as yarn, roving, woven fabric and unidirectional or fabric epoxy laminates. Service temperature is about 180 °C, but the fiber wets out with difficulty, breaks at only 1.5 % strain and remains weak in compression and UV exposure. Kevlar 49 is the more available and easier-to-process alternative. Kevlar 149 has a density of 1.47 g/cm³ (0.0531 lb/in³), lighter than 59% of composite grades. Its glass-transition temperature is 360°C (680 °F). Kevlar 149 has a tensile strength of 3,400 MPa (493 ksi), stronger than 85% of composite grades. Elongation at break is 1.5% and the elastic modulus is 175 GPa (25.4 Msi).
What is Kevlar 149 used for?
- high-stiffness aerospace parts
- pressure vessels
- specialty ropes
Advantages
- Stiff — 175 GPa (25.4 Msi), better than 75% of composite grades
Limitations
- Poor heat conductor — 0.05 W/m·K (0.0289 BTU/hr·ft·°F), worse than 87% of composite grades
- Degrades in UV without stabilisers — 25/100, worse than 86% of composite grades
- Hard to polish — 25/100, worse than 76% of composite grades
Kevlar 149 properties
Typical room-temperature values; bars are the position among composite grades.
Physical4
Kevlar 149 has a density of 1.47 g/cm³ (0.0531 lb/in³), lighter than 59% of composite grades. Its glass-transition temperature is 360°C (680 °F).
Mechanical6
Kevlar 149 has a tensile strength of 3,400 MPa (493 ksi), stronger than 85% of composite grades. Elongation at break is 1.5% and the elastic modulus is 175 GPa (25.4 Msi).
Thermal8
Kevlar 149 is rated for continuous service to 180°C (356 °F). It conducts heat at 0.05 W/m·K (0.0289 BTU/hr·ft·°F), worse than 87% of composite grades. Thermal expansion is -4 µm/m·K (-2.22 µin/in·°F).
Electrical4
Kevlar 149 has an electrical resistivity of 1×10¹³ Ω·m.
Chemical & Environmental3
Corrosion resistance is good (65/100), worse than 72% of composite grades. UV resistance is poor.
Sustainability4
Producing a kilogram of Kevlar 149 takes about 285 MJ of energy and emits 16 kg of CO₂ — more than 65% of composite grades. Typical recycled content is 0%.
Manufacturability2
Kevlar 149's machinability is poor (25/100, worse than 65% of composite grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the composite family
Yield strength against density for every composite grade FabDigit runs. Kevlar 149 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Kevlar 149
Is Kevlar 149 easy to machine?
Cut with hot knife, ultrasonic blade or shear-type scissors; drill laminates with special aramid (C-point/brad) drills and backing plate to avoid fuzz and delamination.
Can Kevlar 149 be welded?
Not weldable — join by adhesive bonding, mechanical fasteners with bushings, or co-cured composite splices.
Can Kevlar 149 be formed, bent or molded?
Processed as prepreg autoclave lay-up, RTM/VARTM or filament winding; the fiber is difficult to wet out and cannot be hot-formed, so drape and tack are controlled by the matrix.
Kevlar 149 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 |
|---|---|---|
| finish / sizingSurface finish level depends on yarn type (standard, epoxy-compatible, rubber-compatible) | 0.1 – 1 | 0.5 |
| poly(p-phenylene terephthalamide) (PPTA)Condensation polymer of p-phenylenediamine and terephthaloyl chloride; Kevlar 149 has the highest crystallinity/orientation of the series | balance |
What surface finishes work on Kevlar 149?
Seal cut edges with resin or edge tape to stop wicking and fuzzing; paint or gelcoat with UV-blocking pigment since bare aramid yellows and loses strength in sunlight.
How much does Kevlar 149 cost?
Kevlar 149 is a high-cost composite ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Kevlar 149 — frequently asked
What is Kevlar 149 used for?
Kevlar 149 is typically used for high-stiffness aerospace parts, pressure vessels and specialty ropes. In short: stiffest para-aramid grade; lowest aramid moisture pickup; hard to wet out.
What is the tensile strength of Kevlar 149?
Kevlar 149 has a typical tensile strength of 3,400 MPa (493 ksi) — stronger than 85% of composite grades. Strength varies by condition: see the 2 listed tempers.
Is Kevlar 149 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 65% of composite grades). Cut with hot knife, ultrasonic blade or shear-type scissors; drill laminates with special aramid (C-point/brad) drills and backing plate to avoid fuzz and delamination.
Can Kevlar 149 be welded?
Not weldable — join by adhesive bonding, mechanical fasteners with bushings, or co-cured composite splices.
What surface finishes work on Kevlar 149?
Seal cut edges with resin or edge tape to stop wicking and fuzzing; paint or gelcoat with UV-blocking pigment since bare aramid yellows and loses strength in sunlight.
Can Kevlar 149 be formed, bent or molded?
Processed as prepreg autoclave lay-up, RTM/VARTM or filament winding; the fiber is difficult to wet out and cannot be hot-formed, so drape and tack are controlled by the matrix.
What is the maximum service temperature of Kevlar 149?
Kevlar 149 is rated for continuous use to about 180°C (356 °F), and briefly to 300°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Kevlar 149 cost?
Kevlar 149 is a high-cost composite ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Kevlar Technical Guide (aramid fiber properties, K29/K49/K149) — DuPont (2017)
- ASM Handbook Vol. 21: Composites — ASM International (2001)
- ASTM D7269 — Tensile Testing of Aramid Yarns — ASTM International (2020)
- MatWeb / CES EduPack aramid fiber and aramid-epoxy laminate records — MatWeb LLC / Granta (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.