Kevlar 29 PULP
Grade
PULP = highly fibrillated aramid pulp
Asbestos-replacement thickener/reinforcement for brake pads, clutch facings, gaskets, sealants and drilling fluids.
Values for the PULP condition
Other Kevlar 29 grades and fills
Kevlar 29 is listed in 5 conditions; see the grade overview at Kevlar 29.
Compare all 5 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Woven Kevlar 29 fabric / epoxy laminate, Vf ≈ 50 % | Balanced quasi-isotropic panels — canoe hulls, protective shells, drone and motorsport bodywork with damage tolerance. | — | 500 | 2.2 | — |
Unidirectional Kevlar 29 / epoxy laminate, Vf ≈ 60 % | Use where axial tensile stiffness and impact/energy absorption matter and compressive load is low (pressure-vessel overwrap, panels, radomes). | — | 1,350 | 2 | — |
Braided/twisted K29 rope and sling cordage | Pick for low-stretch, non-conductive lifting slings, mooring and tow lines where creep and UV exposure are controlled. | — | 1,800 | 3 | — |
PULPThis page Highly fibrillated aramid pulp | Asbestos-replacement thickener/reinforcement for brake pads, clutch facings, gaskets, sealants and drilling fluids. | — | 2,900 | 3.6 | — |
Kevlar 29 AP | Pick when ~15 % more break strength per denier is needed in the same K29 modulus class (ropes, slings, thinner ballistic packs). | — | 3,400 | 3.6 | — |
What is Kevlar 29 PULP?
Kevlar 29 PULP is Kevlar 29 in the PULP grade — asbestos-replacement thickener/reinforcement for brake pads, clutch facings, gaskets, sealants and drilling fluids. Kevlar 29 PULP has a tensile strength of 2,900 MPa (421 ksi), stronger than 80% of composite grades. Elongation at break is 3.6% and the elastic modulus is 70 GPa (10.2 Msi). Kevlar 29 PULP 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).
Advantages
- Ductile — tolerates forming and impact — 3.6%, better than 81% of composite grades
Limitations
- Degrades in UV without stabilisers — 20/100, worse than 94% of composite grades
- Absorbs moisture — dry before molding — 4%, worse than 93% of composite grades
- Hard to polish — 20/100, worse than 90% of composite grades
- Poor heat conductor — 0.05 W/m·K (0.0289 BTU/hr·ft·°F), worse than 87% of composite grades
- Difficult to machine — 20/100, worse than 77% of composite grades
Kevlar 29 PULP properties
Typical room-temperature values for Kevlar 29 PULP; 11 are specific to this condition. Other listed values are Kevlar 29 reference data and may not represent this condition. Bars are the position among composite grades.
Physical4
Kevlar 29 PULP 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).
Mechanical6
Kevlar 29 PULP has a tensile strength of 2,900 MPa (421 ksi), stronger than 80% of composite grades. Elongation at break is 3.6% and the elastic modulus is 70 GPa (10.2 Msi).
Thermal8
Kevlar 29 PULP is rated for continuous service to 200°C (392 °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 -2 µm/m·K (-1.11 µin/in·°F).
Electrical4
Kevlar 29 PULP 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 29 PULP takes about 270 MJ of energy and emits 13 kg of CO₂ — more than 60% of composite grades. Typical recycled content is 0%.
Manufacturability2
Kevlar 29 PULP'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 29 PULP
Is Kevlar 29 easy to machine?
Cut with sharp serrated/shear scissors, hot knife or waterjet; drilling and routing of laminates need special aramid (C-type/brad-point) tooling, backing plates and high rake angles to avoid fuzzing and delamination.
Can Kevlar 29 be welded?
Not weldable or fusible — the fibre decomposes near 500 °C without melting; joints are made by stitching, braiding, splicing or adhesive/resin bonding.
Can Kevlar 29 be formed, bent or molded?
Processed as textile (weaving, braiding, filament winding) or as prepreg/RTM laminate; dry the fibre before impregnation (moisture regain ~4–7 %) and keep cure below ~180 °C for standard epoxies.
What surface finishes work on Kevlar 29?
Edges should be resin-sealed or bound to stop fraying; laminates must be painted, gel-coated or fabric-covered because unprotected aramid loses strength rapidly in sunlight.
Kevlar 29 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) unitmonomer share of the repeat unit (mol basis) | ≈ 45 | 45 |
| terephthaloyl chloride (TCl) unitmonomer share of the repeat unit (mol basis) | ≈ 55 | 55 |
| spin finish / sizingtextile or RFL-compatible finish depending on end use | 0.1 – 0.8 | 0.4 |
| poly(p-phenylene terephthalamide) (PPTA)condensation polymer of p-phenylenediamine + terephthaloyl chloride, liquid-crystal spun from sulfuric acid | balance | — |
Kevlar 29 PULP — frequently asked
What is Kevlar 29 PULP used for?
Kevlar 29 PULP is typically used for ballistic vests, ropes and cables, protective fabrics, tire reinforcement and friction materials. In short: baseline industrial para-aramid; highest-toughness aramid grade; rope and ballistic workhorse.
What is the tensile strength of Kevlar 29 PULP?
Kevlar 29 PULP has a typical tensile strength of 2,900 MPa (421 ksi) — stronger than 80% of composite grades. Strength varies by condition: see the 5 listed tempers.
Is Kevlar 29 PULP easy to machine?
Not especially — machinability is rated poor (20/100, worse than 77% of composite grades). Cut with sharp serrated/shear scissors, hot knife or waterjet; drilling and routing of laminates need special aramid (C-type/brad-point) tooling, backing plates and high rake angles to avoid fuzzing and delamination.
Can Kevlar 29 PULP be welded?
Not weldable or fusible — the fibre decomposes near 500 °C without melting; joints are made by stitching, braiding, splicing or adhesive/resin bonding.
What surface finishes work on Kevlar 29 PULP?
Edges should be resin-sealed or bound to stop fraying; laminates must be painted, gel-coated or fabric-covered because unprotected aramid loses strength rapidly in sunlight.
Can Kevlar 29 PULP be formed, bent or molded?
Processed as textile (weaving, braiding, filament winding) or as prepreg/RTM laminate; dry the fibre before impregnation (moisture regain ~4–7 %) and keep cure below ~180 °C for standard epoxies.
What is the maximum service temperature of Kevlar 29 PULP?
Kevlar 29 PULP is rated for continuous use to about 200°C (392 °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 (H-77848) — DuPont (2017)
- ASM Handbook Vol. 21 — Composites — ASM International (2001)
- ASTM D7269 — Tensile Testing of Aramid Yarns — ASTM International (2020)
- Granta/CES EduPack — Aramid fibre and aramid/epoxy composite 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.