PNR · additive grade
PNR-MB
Properties of the MB condition, compared with the other PNR grades.
Use 5–30 phr of PNR powder in a conventional rubber to raise damping, grip and oil-carrying capacity.
What is PNR-MB?
PNR-MB is PNR in the MB grade — use 5–30 phr of PNR powder in a conventional rubber to raise damping, grip and oil-carrying capacity. PNR-MB has a tensile strength of 12 MPa (1.74 ksi), weaker than 76% of polymer grades. Elongation at break is 400% and the elastic modulus is 0 GPa (4.35×10⁻⁴ Msi). PNR-MB has a density of 1 g/cm³ (0.0361 lb/in³), lighter than 72% of polymer grades. Its glass-transition temperature is -25°C (-13 °F). SA40 is the default condition FabDigit quotes; MB is available on request or by drawing note.
Advantages
- Ductile — tolerates forming and impact — 400%, better than 86% of polymer grades
- Forms and bends easily — 85/100, better than 82% of polymer grades
Limitations
- Difficult to machine — 20/100, worse than 97% of polymer grades
- Low stiffness — 0 GPa (4.35×10⁻⁴ Msi), worse than 93% of polymer grades
- High mold shrinkage — 2%, worse than 81% of polymer grades
PNR-MB properties
Typical room-temperature values for PNR-MB — 3 properties are specific to this condition; the rest are grade-level values shared by every PNR grade. Each bar shows where the value sits among the polymer grades in FabDigit's library — further right is higher.
Physical3
PNR-MB has a density of 1 g/cm³ (0.0361 lb/in³), lighter than 72% of polymer grades. Its glass-transition temperature is -25°C (-13 °F).
Mechanical8
PNR-MB has a tensile strength of 12 MPa (1.74 ksi), weaker than 76% of polymer grades. Elongation at break is 400% and the elastic modulus is 0 GPa (4.35×10⁻⁴ Msi).
Thermal8
PNR-MB is rated for continuous service to 90°C (194 °F). It conducts heat at 0.2 W/m·K (0.116 BTU/hr·ft·°F), worse than 56% of polymer grades. Thermal expansion is 220 µm/m·K (122.2 µin/in·°F).
Electrical4
PNR-MB is an electrical insulator with a dielectric strength of 18 kV/mm (457.2 V/mil) and a resistivity of 1×10¹¹ Ω·m.
Chemical & Environmental2
UV resistance is fair.
Sustainability4
Producing a kilogram of PNR-MB takes about 105 MJ of energy and emits 4.5 kg of CO₂ — more than 54% of polymer grades. Typical recycled content is 0%.
Manufacturability4
PNR-MB's machinability is poor (20/100, worse than 97% of polymer grades); formability excellent (85/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other PNR grades and fills
PNR is also supplied in 8 other conditions. The full side-by-side table is on the PNR overview.
- SA40DefaultDefault engineering compound: best compromise of damping, strength and processability for molded damping parts.8 MPa tensile
- SA60Choose when higher load capacity, abrasion and grip are needed (rolls, non-slip pads) and damping can be traded off.12 MPa tensile
- SA15Use for very soft seat/instrument damping pads and low-frequency isolators where deflection matters more than strength.4 MPa tensile
- MBUse 5–30 phr of PNR powder in a conventional rubber to raise damping, grip and oil-carrying capacity.12 MPa tensile
Working with PNR-MB
Is PNR easy to machine?
Too soft and tacky for conventional cutting — use water-jet, die cutting or cryogenic trimming; freeze before grinding.
Can PNR be welded?
Not weldable; join by co-vulcanization, adhesive bonding (cyanoacrylate/polyurethane after surface priming) or mechanical capture.
Can PNR be formed, bent or molded?
Mix on cold two-roll mill or internal mixer at low temperature (oil is absorbed rapidly), then compression/transfer/injection mold and cure 5–20 min at 150–170 °C with sulfur or peroxide.
What surface finishes work on PNR?
No plating or painting; surface can be textured in the mold, dusted with talc/silicone to kill tack, or coated with a flock/lacquer for abrasion and oil-bleed control.
PNR 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 |
|---|---|---|
| extender oil (naphthenic/paraffinic or ephr on polymer; sets hardness and Tg of the compound | 50 – 500 | 200 |
| carbon black / mineral fillerphr, reinforcement | 0 – 100 | 30 |
| sulfur or peroxide cure system + activatphr | 2 – 8 | 5 |
| antioxidant / antiozonantphr | 1 – 3 | 2 |
| polynorbornene (bicyclo[2.2.1]hept-2-enebase polymer, Mw typically >2×10^6 g/mol, ~90% trans ring-opened units | balance | — |
PNR-MB — frequently asked
What is PNR-MB used for?
PNR-MB is typically used for vibration damping mounts, sound insulation and oil-extended soft compounds. In short: softest oil-extended elastomer; high-hysteresis damping compounds; shore A 15 achievable.
What is the tensile strength of PNR-MB?
PNR-MB has a typical tensile strength of 12 MPa (1.74 ksi) — weaker than 76% of polymer grades. Strength varies by condition: see the 9 listed tempers.
Is PNR-MB easy to machine?
Not especially — machinability is rated poor (20/100, worse than 97% of polymer grades). Too soft and tacky for conventional cutting — use water-jet, die cutting or cryogenic trimming; freeze before grinding.
Can PNR-MB be welded?
Not weldable; join by co-vulcanization, adhesive bonding (cyanoacrylate/polyurethane after surface priming) or mechanical capture.
What surface finishes work on PNR-MB?
No plating or painting; surface can be textured in the mold, dusted with talc/silicone to kill tack, or coated with a flock/lacquer for abrasion and oil-bleed control.
Can PNR-MB be formed, bent or molded?
Mix on cold two-roll mill or internal mixer at low temperature (oil is absorbed rapidly), then compression/transfer/injection mold and cure 5–20 min at 150–170 °C with sulfur or peroxide.
What is the maximum service temperature of PNR-MB?
PNR-MB is rated for continuous use to about 90°C (194 °F), and briefly to 120°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- Norsorex APX polynorbornene technical data — Astrotech Advanced Elastomer Products / Zeon (2020)
- Rubber Technology Handbook — specialty elastomers chapter — Hanser (2012)
- Polymer Handbook (Tg and density of polynorbornene) — Wiley (2005)
- ASTM D2000 — classification system for rubber products — ASTM (2018)
- Norsorex (2025)
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.