Natural Rubber (NR)
The original elastomer, still unmatched for resilience and fatigue life. That makes it the default for vibration mounts, bushings and non-marking wheels — and useless in oil or in direct sun.
Properties
- Family
- Rubber
- Category
- rubber
- Density
- 0.93 g/cm³ · 930 kg/m³
Densityhow natural rubber (nr) compares
Rubber propertiescis-1,4-polyisoprene (Hevea latex) · family range, not a compound guarantee
- ASTM designation
- NR · D2000 AA
- Shore A hardness
- 70 · the sealing default, selected for the gland rather than the polymer
- Service temperature
- -50 to 70 °C · -58 to 158 °F
- Typical media
- Water, alcohols, organic acids, refrigerants
Family screening range from Apple Rubber standard compound figure (dry heat) — the range for the polymer family, not for any one compound. Within a family the filler and cure system move the limit by tens of degrees, so the compound data sheet governs the finished part.
The grey figures are converted at °F = °C × 9/5 + 32; the Celsius numbers are the published ones.
Applicationswhere natural rubber (nr) is normally specified
Service & sealingtrade experience, not measured values
- Oil & fuel
- Poor. Hydrocarbons swell it and it has no place in a fuel or oil system — that is what nitrile is for.
- Weather & ozone
- Poor unprotected. The unsaturated backbone that gives it its resilience also makes it the first thing ozone attacks; waxes and antiozonants slow it, they do not fix it.
- Sealing
- Vibration isolation rather than sealing: mounts, bushings, bumpers, non-marking wheels, conveyor lagging. Bond it to a metal insert during vulcanisation for a mount that needs no adhesive.
These lines are not measurements: no units, no single source. They describe how the family is generally found to behave — which media it survives and what it will seal — rather than what any one compound is guaranteed to do. The media a joint will meet decides the family before the temperature does.
Practical notes
- Poor resistance to oils, fuels, ozone and UV — the double bond in the backbone is why
- Lowest heat resistance of the common rubbers; it ages fast above about 80 °C
- Highest tear and tensile strength of the family, which is what keeps it in use