Cyanate Ester vs PBI
Polymer · grade comparison
Cyanate Ester and PBI are both polymer grades. PBI is the stronger of the two: tensile strength 160 MPa (23.2 ksi) against 80 MPa (11.6 ksi) for Cyanate Ester, about 100% more. PBI is the more ductile: elongation 3% versus 2.6% for Cyanate Ester. Cyanate Ester is lighter (1.21 g/cm³ vs 1.3 g/cm³ for PBI) and PBI is stiffer (5.9 GPa vs 3.1 GPa). On the shop floor, Cyanate Ester sits in a lower cost tier (high, $$$$) than PBI (specialty, $$$$$).
Cyanate EsterChoose it when weight is the constraint, or when cost is the deciding factor.
PBIChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
Cyanate Ester vs PBI: 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
Poisson's Ratio
Tensile Strength (Ultimate)
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
Physical
Density and transition temperatures.
Density
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)
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Constant (1 MHz)
Volume Resistivity
Surface Resistivity
Comparative Tracking Index (CTI)
Same in both: Dielectric Strength 22 kV/mm559 V/mil · Dissipation Factor (1 MHz) 0.004
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
Polishability
Mold Shrinkage
Processing Melt Temperature (typ.)
Mold Temperature (typ.)
Same in both: Formability (cold) 5 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 0%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Thermal Diffusivity
Same in both: 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 | Cyanate Ester | PBI |
|---|---|---|
| CNC machining | — | Yes |
| Sheet metal | — | Yes |
| Injection molding | — | Yes |
| Default condition | — | Unfilled |
| Relative cost | $$$$ High | $$$$$ Specialty |
| Min. machined wall | — | 0.5 mm |
| Best machined surface | — | Ra 0.8 µm |
| Chrome Plating (Plastic) | — | Yes |
| EMI Shielding Coating | — | Yes |
| Painting | — | Yes |
| Soft Touch Coating | — | Yes |
| Spray Painting | — | Yes |
| UV Coating | — | Yes |
Cyanate Ester vs PBI — frequently asked
Is PBI stronger than Cyanate Ester?
Yes. PBI has a typical tensile strength of 160 MPa (23.2 ksi) against 80 MPa (11.6 ksi) for Cyanate Ester — about 100% more.
Which is cheaper, Cyanate Ester or PBI?
Cyanate Ester is the lower-cost material: it sits in the high tier ($$$$) while PBI is specialty ($$$$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
Which is easier to machine, Cyanate Ester or PBI?
Cyanate Ester. Its machinability rates good (55/100) against fair (50/100) for PBI; for welding the order is PBI first (not recommended, 5/100) then Cyanate Ester (not recommended, 0/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in Cyanate Ester and PBI 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.