HNBR SULF
Additive grade
also Therban, Zetpol
SULF = sulfur-cured partially hydrogenated compound
Cheaper, more flex-fatigue tolerant (belts, boots) but heat life is clearly lower than peroxide-cured HNBR.
Values for the SULF condition
Other HNBR grades and fills
HNBR is listed in 9 conditions; see the grade overview at HNBR.
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 |
SULFThis page 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 |
What is HNBR SULF?
HNBR SULF is HNBR in the SULF grade — cheaper, more flex-fatigue tolerant (belts, boots) but heat life is clearly lower than peroxide-cured HNBR. HNBR SULF has a tensile strength of 24 MPa (3.48 ksi), weaker than 68% of polymer grades. Elongation at break is 350% and the elastic modulus is 0.01 GPa (9.43×10⁻⁴ Msi). HNBR SULF 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). A70 is the default condition FabDigit quotes; SULF is available on request or by drawing note.
Advantages
- Forms and bends easily — 91/100, better than 97% of polymer grades
- Good UV / weathering resistance — 75/100, better than 85% of polymer grades
- Ductile — tolerates forming and impact — 350%, better than 84% of polymer grades
- High service temperature — 135°C (275 °F), better than 75% of polymer grades
Limitations
- Difficult to machine — 28/100, worse than 90% of polymer grades
- High mold shrinkage — 2.4%, worse than 89% of polymer grades
- Low stiffness — 0.01 GPa (9.43×10⁻⁴ Msi), worse than 85% of polymer grades
- Absorbs moisture — dry before molding — 1%, worse than 84% of polymer grades
HNBR SULF properties
Typical room-temperature values for HNBR SULF; 16 are specific to this condition. Other listed values are HNBR reference data and may not represent this condition. Bars are the position among polymer grades.
Physical3
HNBR SULF 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 SULF has a tensile strength of 24 MPa (3.48 ksi), weaker than 68% of polymer grades. Elongation at break is 350% and the elastic modulus is 0.01 GPa (9.43×10⁻⁴ Msi).
Thermal7
HNBR SULF is rated for continuous service to 135°C (275 °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 SULF 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 (72/100), worse than 70% of polymer grades. UV resistance is very good.
Sustainability3
Producing a kilogram of HNBR SULF 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 SULF's machinability is poor (28/100, worse than 90% of polymer grades); formability excellent (91/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with HNBR SULF
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.
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.
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 | — |
HNBR SULF — frequently asked
What is HNBR SULF used for?
HNBR SULF 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 SULF?
HNBR SULF has a typical tensile strength of 24 MPa (3.48 ksi) — weaker than 68% of polymer grades. Strength varies by condition: see the 9 listed tempers.
Is HNBR SULF easy to machine?
Not especially — machinability is rated poor (28/100, worse than 90% 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 SULF 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 SULF?
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 SULF 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 SULF?
HNBR SULF is rated for continuous use to about 135°C (275 °F), and briefly to 170°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.