PEKK vs PPSU
Polymer · grade comparison
PEKK and PPSU are both polymer grades, both high performance plastic. PEKK is the stronger of the two: yield strength 95 MPa (13.8 ksi) against 70 MPa (10.2 ksi) for PPSU, about 36% more; tensile strength follows at 95 MPa (13.8 ksi) vs 70 MPa (10.2 ksi). In exchange, PPSU is the more ductile: elongation 80% versus 8% for PEKK. PEKK is stiffer (3.9 GPa vs 2.3 GPa) and PEKK runs hotter in service (240°C vs 180°C continuous). On the shop floor, PPSU welds better (very good vs good).
PEKKChoose it when strength drives the design, or when the part sees heat.
PPSUChoose it when the part is bent, formed or impact-loaded, or when it will be welded.
PEKK vs PPSU: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all polymer grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all polymer grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Shear Modulus
Bulk Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Compressive Strength
Compressive Modulus
Flexural Strength
Flexural Modulus
Shear Strength
Fracture Toughness (K_IC)
Izod Impact, Notched
Hardness, Shore D
Hardness, Rockwell M
Hardness, Rockwell R
Same in both: Poisson's Ratio 0.4
Physical
Density and transition temperatures.
Density
Melting Temperature (Tm)
Glass Transition (Tg)
Water Absorption (24 h)
Water Absorption (Saturation)
Refractive Index
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Heat Deflection Temp. @ 0.45 MPa
Heat Deflection Temp. @ 1.8 MPa
Limiting Oxygen Index
Max Service Temperature (short-term)
Vicat Softening Point (B50)
Electrical
Conductivity and insulation.
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Surface Resistivity
Comparative Tracking Index (CTI)
Same in both: Electrical Resistivity 1×10¹⁴ Ω·m3.94×10²¹ µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
UV / Weathering Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Weldability
Formability (cold)
Polishability
Mold Shrinkage
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
Melt Flow Rate
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Same in both: Embodied Water 500 L/kg59.9 gal/lb · Typical Recycled Content 0%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Same in both: Thermal Diffusivity 0.2 mm²/s · Thermal Shock Resistance Index 0
Strength versus weight
Yield strength against density for every polymer grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | PEKK | PPSU |
|---|---|---|
| 3D printing | Yes | — |
| CNC machining | — | Yes |
| Sheet metal | — | Yes |
| Injection molding | — | Yes |
| Default condition | Unfilled | Medical Grade |
| Relative cost | $$$$$ Specialty | $$$$$ Specialty |
| Min. machined wall | — | 0.5 mm |
| Best machined surface | — | Ra 0.8 µm |
| Chrome Plating (Plastic) | — | Yes |
| Conductive Coating | Yes | — |
| Dyeing (Nylon) | Yes | — |
| Primer Coating | Yes | — |
| Spray Painting | — | Yes |
| Tinted Coating | Yes | — |
| Vacuum Metallization | Yes | — |
| Waterproof Coating | Yes | — |
They share 4 finishes: EMI Shielding Coating, Painting, Soft Touch Coating, UV Coating.
PEKK vs PPSU — frequently asked
Is PEKK stronger than PPSU?
Yes. PEKK has a typical yield strength of 95 MPa (13.8 ksi) against 70 MPa (10.2 ksi) for PPSU — about 36% more. Tensile strength is 95 MPa (13.8 ksi) vs 70 MPa (10.2 ksi).
Which is cheaper, PEKK or PPSU?
Both sit in the same relative cost tier ($$$$$, specialty); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which welds better, PEKK or PPSU?
PPSU. Its weldability rates very good (70/100) against good (55/100) for PEKK.
Ready to make it?
Upload a CAD file and FabDigit prices the part in PEKK and PPSU side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.