HNBR
also Therban, Zetpol
HNBR (Therban, Zetpol) is a hydrogenated nitrile rubber in which the butadiene unsaturation is largely removed, giving NBR-level oil resistance with far better heat, ozone and abrasion resistance; grades cover 60–90 Shore A plus low-temperature, high-ACN, FDA and high-strength variants.
Reference datasheet — HNBR 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.
Values for the A70 condition
HNBR grades and fills
HNBR is supplied in 9 conditions, soft to hard. A70 is the default FabDigit quotes; the values on this page are for it.
Compare all 9 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Soft compound, Shore A 60 | Pick when low sealing force / good conformity on rough flanges is needed at moderate pressure. | 20 | 350 | 15 Shore D | |
Low-ACN low-temperature grade | Choose for cold-start flexibility down to about −45 °C (A/C, cold-climate belts) at the cost of some oil-swell resistance. | 22 | 330 | 22 Shore D | |
Sulfur-cured partially hydrogenated compound | Cheaper, more flex-fatigue tolerant (belts, boots) but heat life is clearly lower than peroxide-cured HNBR. | 24 | 350 | 20 Shore D | |
A70Default Peroxide-cured black compound, Shore A 70 | General-purpose HNBR seal/O-ring compound; best balance of sealability, heat life and dynamic properties. | 25 | 300 | 22 Shore D | |
High acrylonitrile (≈44 %) oil/fuel-resistant grade | Use where minimum swell in aggressive oils, biodiesel or aromatic fuels matters more than cold flexibility. | 26 | 270 | 23 Shore D | |
Fully saturated (residual double bond < 1 %), peroxide cured | Maximum heat, ozone and oxidation life — use for 150–160 °C continuous oil service and sour-gas seals. | 26 | 280 | 23 Shore D | |
High-modulus compound, Shore A 80 | Higher extrusion resistance for high-pressure static seals, back-up rings and rod seals. | 27 | 240 | 30 Shore D | |
Very hard compound, Shore A 90 | Oilfield packer elements and anti-extrusion parts where high pressure and gas decompression are present. | 28 | 170 | 40 Shore D | |
High-strength reinforced compound | Highly reinforced (fine carbon black, high polymer Mooney) stock for timing belts, rollers and abrasion-critical parts. | 31 | 220 | 29 Shore D |
Supply forms, finishes and certifications
Ways HNBR is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
FDA | Light-coloured food / potable-water compound | Certification |
What is HNBR?
HNBR (Therban, Zetpol) is a hydrogenated nitrile rubber in which the butadiene unsaturation is largely removed, giving NBR-level oil resistance with far better heat, ozone and abrasion resistance; grades cover 60–90 Shore A plus low-temperature, high-ACN, FDA and high-strength variants. It is specified for dynamic seals and belts to about 150 °C, with 25 MPa tensile strength, 300 % elongation and roughly 7 MPa modulus, in O-rings, shaft seals, downhole packers and toothed belts. Cost and lead time are well above NBR and peroxide cures require a post-cure; for higher temperature or more aggressive fluids move to FKM. HNBR has a density of 1.25 g/cm³ (0.0452 lb/in³), heavier than 64% of polymer grades. Its glass-transition temperature is -25°C (-13 °F). HNBR has a tensile strength of 25 MPa (3.63 ksi), weaker than 66% of polymer grades. Elongation at break is 300% and the elastic modulus is 0.01 GPa (0.001 Msi).
What is HNBR used for?
- timing belts
- automotive seals
- oilfield seals
- high-temp hoses
Advantages
- Forms and bends easily — 90/100, better than 91% of polymer grades
- Good UV / weathering resistance — 75/100, better than 85% of polymer grades
- Ductile — tolerates forming and impact — 300%, better than 81% of polymer grades
- High service temperature — 150°C (302 °F), better than 79% of polymer grades
Limitations
- High mold shrinkage — 2.3%, worse than 89% of polymer grades
- Difficult to machine — 30/100, worse than 87% of polymer grades
- Low stiffness — 0.01 GPa (0.001 Msi), worse than 84% of polymer grades
- Absorbs moisture — dry before molding — 1%, worse than 84% of polymer grades
HNBR properties
Typical room-temperature values for HNBR-A70; bars are the position among polymer grades.
Physical3
HNBR has a density of 1.25 g/cm³ (0.0452 lb/in³), heavier than 64% of polymer grades. Its glass-transition temperature is -25°C (-13 °F).
Mechanical9
HNBR has a tensile strength of 25 MPa (3.63 ksi), weaker than 66% of polymer grades. Elongation at break is 300% and the elastic modulus is 0.01 GPa (0.001 Msi).
Thermal7
HNBR is rated for continuous service to 150°C (302 °F). It conducts heat at 0.25 W/m·K (0.144 BTU/hr·ft·°F), better than 72% of polymer grades. Thermal expansion is 220 µm/m·K (122.2 µin/in·°F).
Electrical4
HNBR is an electrical insulator with a dielectric strength of 16 kV/mm (406.4 V/mil) and a resistivity of 1×10⁸ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (80/100), worse than 52% of polymer grades. UV resistance is very good.
Sustainability3
Producing a kilogram of HNBR takes about 130 MJ of energy and emits 5 kg of CO₂ — more than 77% of polymer grades. Typical recycled content is 0%.
Manufacturability5
HNBR's machinability is poor (30/100, worse than 87% of polymer grades); formability excellent (90/100).
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 polymer family
Yield strength against density for every polymer grade FabDigit runs. HNBR is highlighted; hover a dot for its name, or open the interactive family chart.
Working with HNBR
Is HNBR easy to machine?
Cured HNBR is best cut by waterjet, die/kiss-cutting or cryogenic deflashing; conventional turning/milling needs sharp tools, air cooling and frozen or mandrel-supported parts to avoid tearing.
Can HNBR be welded?
Thermoset — cannot be welded; join by adhesive bonding (cyanoacrylate or epoxy after plasma/chemical surface activation) or by co-vulcanising to metal with phenolic/silane bonding agents.
Can HNBR be formed, bent or molded?
Compression, transfer or injection mould peroxide compounds at 175–200 °C with a post-cure of 2–4 h at 150–175 °C to develop full heat resistance and low compression set; keep mould release and mixing free of sulfur contamination.
HNBR 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 |
|---|---|---|
| acrylonitrile (ACN) comonomerwt % of the polymer; 34–39 % typical for seal grades | 17 – 50 | 36 |
| carbon black (N330/N550/N770)phr in the compound; replaced by silica/silicate in light-coloured grades | 20 – 60 | 40 |
| peroxide cure system + coagent (TAIC/TACphr; sulfur/accelerator system in partially hydrogenated grades | 3 – 10 | 6 |
| plasticiser / ester or ether plasticiserphr, low-temperature and processing aid | 0 – 15 | 5 |
| ZnO, anti-oxidant (ZMTI/TMQ), processingphr | 3 – 10 | 6 |
| hydrogenated butadieneresidual double bond 0.3–5.5 mol % depending on saturation level | balance |
What surface finishes work on HNBR?
Cryogenic tumble deflashing is standard; surfaces can be talc/PTFE-coated, plasma-treated or parylene-coated for low friction, and metal-to-rubber bonded assemblies are grit-blasted and primed before moulding.
Equivalent designations
Standards and trade names that resolve to HNBR in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- TherbanZetpol
- Also called
- HSN
How much does HNBR cost?
HNBR is a high-cost polymer ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
HNBR — frequently asked
What is HNBR used for?
HNBR is typically used for timing belts, automotive seals, oilfield seals and high-temp hoses. In short: heat-resistant NBR upgrade; 150 °C oil-resistant seals; costlier than NBR.
What is the tensile strength of HNBR?
HNBR has a typical tensile strength of 25 MPa (3.63 ksi) — weaker than 66% of polymer grades. Strength varies by condition: see the 9 listed tempers.
Is HNBR easy to machine?
Not especially — machinability is rated poor (30/100, worse than 87% of polymer grades). Cured HNBR is best cut by waterjet, die/kiss-cutting or cryogenic deflashing; conventional turning/milling needs sharp tools, air cooling and frozen or mandrel-supported parts to avoid tearing.
Can HNBR be welded?
Thermoset — cannot be welded; join by adhesive bonding (cyanoacrylate or epoxy after plasma/chemical surface activation) or by co-vulcanising to metal with phenolic/silane bonding agents.
What surface finishes work on HNBR?
Cryogenic tumble deflashing is standard; surfaces can be talc/PTFE-coated, plasma-treated or parylene-coated for low friction, and metal-to-rubber bonded assemblies are grit-blasted and primed before moulding.
Can HNBR be formed, bent or molded?
Compression, transfer or injection mould peroxide compounds at 175–200 °C with a post-cure of 2–4 h at 150–175 °C to develop full heat resistance and low compression set; keep mould release and mixing free of sulfur contamination.
What is the maximum service temperature of HNBR?
HNBR is rated for continuous use to about 150°C (302 °F), and briefly to 170°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does HNBR cost?
HNBR is a high-cost polymer ($$$$), 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
- Therban HNBR product and compound data — Arlanxeo (2023)
- Zetpol hydrogenated nitrile rubber technical data — Zeon Chemicals (2022)
- Parker O-Ring Handbook ORD 5700 (HNBR/HSN compound section) — Parker Hannifin (2021)
- Engineered Materials Handbook Vol. 2: Engineering Plastics and Elastomers — ASM International (1988)
- ASTM D2000 — Classification System for Rubber Products in Automotive Applications — ASTM (2020)
- GB/T 528 / GB/T 531.1 rubber tensile and hardness test methods — SAC (2009)
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.