NBR XNBR
Grade
also Nitrile Rubber, Buna-N
XNBR = carboxylated nitrile
Use where abrasion and tear resistance govern (rod seals, rollers, gloves); slightly stiffer and less compression-set tolerant.
Values for the XNBR condition
Other NBR grades and fills
NBR is listed in 14 conditions; see the grade overview at NBR.
Compare all 14 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Closed-cell / expanded NBR foam | Pick for low-closure-force gasketing, oil-resistant insulation and vibration/acoustic padding where compressibility beats strength. | — | 2 | 150 | 20 Shore A |
Shore A 40 | Soft, highly conformable compound for low-pressure gaskets and diaphragms on rough flanges. | — | 8 | 550 | 40 Shore A |
Shore A 50 | Compliant sealing compound for static gaskets and low-load bellows. | — | 11 | 500 | 50 Shore A |
Flame-retardant compound | Halogen or ATH loaded compound for mining hose, cable jackets and rail applications requiring flame/smoke ratings. | — | 11 | 280 | 25 Shore D |
Shore A 60 | General O-ring hardness for moderate-pressure hydraulic and pneumatic seals. | — | 13 | 450 | 60 Shore A |
Low-temperature grade | Pick for cold-climate seals down to about -45 °C, accepting more swell in fuels and oils. | — | 14 | 450 | 18 Shore D |
NBR/PVC blend | Choose for outdoor hose covers, cable jackets and fuel-line outer layers needing ozone/UV resistance with oil resistance. | — | 14 | 350 | 22 Shore D |
Conductive / antistatic | Specify for fuel-handling hose liners, rollers and pads where static must be bled off. | — | 14 | 280 | 28 Shore D |
SolidDefault Dense vulcanized compound | Default choice for O-rings, gaskets, oil seals and hose liners where sealing force and oil resistance matter. | — | 16 | 400 | 22 Shore D |
Shore A 70 | The default NBR seal hardness; best balance of extrusion resistance and sealability. | — | 16 | 400 | 22 Shore D |
Shore A 80 | Harder compound for high-pressure seals, backup rings and shaft seals resisting extrusion. | — | 18 | 300 | 30 Shore D |
High-ACN | Choose for aromatic fuels, biodiesel and aggressive oils where swell must be minimized; accepts a warmer low-temperature limit. | — | 18 | 350 | 25 Shore D |
Shore A 90 | Use where extrusion/gap resistance or wear dominates (rod wipers, high-pressure back-ups); low sealing compliance. | — | 20 | 200 | 38 Shore D |
XNBRThis page Carboxylated nitrile | Use where abrasion and tear resistance govern (rod seals, rollers, gloves); slightly stiffer and less compression-set tolerant. | — | 24 | 350 | 25 Shore D |
What is NBR XNBR?
NBR XNBR is NBR in the XNBR grade — use where abrasion and tear resistance govern (rod seals, rollers, gloves); slightly stiffer and less compression-set tolerant. NBR XNBR 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 (0.0012 Msi). NBR XNBR has a density of 1.25 g/cm³ (0.0452 lb/in³), heavier than 64% of polymer grades. Its glass-transition temperature is -35°C (-31 °F). Solid is the default condition FabDigit quotes; XNBR is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 350%, better than 84% of polymer grades
Limitations
- Needs corrosion protection — 55/100, worse than 94% of polymer grades
- Difficult to machine — 28/100, worse than 90% of polymer grades
- Low stiffness — 0.01 GPa (0.0012 Msi), worse than 82% of polymer grades
- Difficult to weld — 10/100, worse than 82% of polymer grades
- High mold shrinkage — 1.9%, worse than 75% of polymer grades
NBR XNBR properties
Typical room-temperature values for NBR XNBR; 15 are specific to this condition. Other listed values are NBR reference data and may not represent this condition. Bars are the position among polymer grades.
Physical4
NBR XNBR has a density of 1.25 g/cm³ (0.0452 lb/in³), heavier than 64% of polymer grades. Its glass-transition temperature is -35°C (-31 °F).
Mechanical9
NBR XNBR 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 (0.0012 Msi).
Thermal8
NBR XNBR is rated for continuous service to 100°C (212 °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 230 µm/m·K (127.8 µin/in·°F).
Electrical5
NBR XNBR 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 good (55/100), worse than 94% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of NBR XNBR takes about 110 MJ of energy and emits 4.5 kg of CO₂ — more than 64% of polymer grades. Typical recycled content is 5%.
Manufacturability5
NBR XNBR's machinability is poor (28/100, worse than 90% of polymer grades); weldability not recommended (10/100); formability good (60/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with NBR XNBR
Is NBR easy to machine?
Cured NBR can be lathe-turned, die-cut, waterjet or cryo-ground with very sharp tools and air cooling; expect tearing and dimensional rebound rather than chip formation.
Can NBR be welded?
Not weldable — join by cold-bonding cyanoacrylate/contact adhesive or by hot vulcanized splicing with uncured gum and a press.
Can NBR be formed, bent or molded?
Compression, transfer or injection molded and cured 3–10 min at 150–200 °C (sulfur or peroxide), with post-cure 2–4 h at 150 °C for low compression set; allow ~2 % shrinkage.
What surface finishes work on NBR?
Deflash by cryogenic tumbling; surfaces can be talc/PTFE dusted, chlorinated or plasma treated to cut friction, and no painting/plating is normally used.
NBR 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 |
|---|---|---|
| acrylonitrilewt % of the copolymer; sets oil resistance vs low-temperature flexibility | 18 – 50 | 34 |
| carbon blackphr of compound, N550/N774 typical reinforcing filler | 20 – 60 | 40 |
| plasticizer (ester/DOP-type)phr, for softness and low-temperature performance | 0 – 20 | 8 |
| zinc oxidephr, cure activator | ≈ 5 | 5 |
| stearic acidphr, activator/process aid | ≈ 1 | 1 |
| sulfur + acceleratorsphr; peroxide cure used for lower compression set | 0.3 – 2.5 | 1.5 |
| antioxidant / antiozonantphr, TMQ/amine type | ≈ 2 | 2 |
| butadienebalance of the copolymer backbone | balance | — |
NBR XNBR — frequently asked
What is NBR XNBR used for?
NBR XNBR is typically used for O-rings, fuel hoses and hydraulic seals. In short: oil-resistant nitrile rubber.
What is the tensile strength of NBR XNBR?
NBR XNBR has a typical tensile strength of 24 MPa (3.48 ksi) — weaker than 68% of polymer grades. Strength varies by condition: see the 14 listed tempers.
Is NBR XNBR easy to machine?
Not especially — machinability is rated poor (28/100, worse than 90% of polymer grades). Cured NBR can be lathe-turned, die-cut, waterjet or cryo-ground with very sharp tools and air cooling; expect tearing and dimensional rebound rather than chip formation.
Can NBR XNBR be welded?
Not readily — weldability is rated not recommended (10/100). Not weldable — join by cold-bonding cyanoacrylate/contact adhesive or by hot vulcanized splicing with uncured gum and a press.
What surface finishes work on NBR XNBR?
Deflash by cryogenic tumbling; surfaces can be talc/PTFE dusted, chlorinated or plasma treated to cut friction, and no painting/plating is normally used.
Can NBR XNBR be formed, bent or molded?
Compression, transfer or injection molded and cured 3–10 min at 150–200 °C (sulfur or peroxide), with post-cure 2–4 h at 150 °C for low compression set; allow ~2 % shrinkage.
What is the maximum service temperature of NBR XNBR?
NBR XNBR is rated for continuous use to about 100°C (212 °F), and briefly to 130°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in NBR XNBR?
Yes — NBR XNBR is available for injection molding; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM D2000 — Classification System for Rubber Products in Automotive Applications — ASTM (2020)
- ASTM D412 / D2240 / D395 / D624 (tensile, hardness, compression set, tear) — ASTM (2021)
- ASM Engineered Materials Handbook Vol. 2 — Engineering Plastics & Elastomers — ASM International (1988)
- Rubber Technology / Science and Technology of Rubber (elastomer property tables) — Springer / Academic Press (2013)
- Nitrile (NBR) seal compound and O-ring material datasheets — Parker Hannifin / Trelleborg Sealing Solutions (2023)
- Perbunan / Krynac NBR grade datasheets — Arlanxeo (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.