Natural Rubber (NR) for Custom Molded Components — Properties, Applications & Specifications
Table of Contents
Material Properties & Specifications
| Common names / abbreviations | Natural Rubber (NR) |
|---|---|
| Polymer structure / monomer system | cis-1,4-polyisoprene |
| Tg (°C) / Brittle Point | -73 °C |
| Density (g/cm³) | 0.92 - 0.93 |
| Hardness range (Shore A/D) | 30 - 90 Shore A |
| Tensile strength (MPa) | 24.1 - 31.0 |
| Elongation at break (%) | 500 - 700 |
| 100% / 300% modulus (MPa) | 1.03 - 20.6 at 100% |
| Rebound / tanδ (temp + freq) | 80 % Rebound |
| Compression set (%) | 10 - 30 % |
| Continuous service temp (°C) | -51°C to 104°C |
| Environmental & Fluid Resistance | Ozone/UV: Poor | Pet/IRM 903: Poor |
| ASTM D2000 Callouts | ASTM D2000 M1AA 417 |
| Electrical properties | Dielectric constant: 2.7 - 4.0 |
| Thermal properties | Thermal Cond: 0.082 - 0.15 W/mK |
| Typical formulation ranges (phr) | Sulfur: 2.5 phr, Sulfenamide: 0.7 phr |
| Tear Resistance | Tier 5 - Excellent |
| Abrasion Resistance | Tier 4 - Strong |
| Gas Impermeability Resistance | Tier 2 - Limited |
| Oxygen Resistance | Tier 2 - Limited |
| Ozone Resistance | Tier 1 - Basic |
| Weathering Resistance | Tier 2 - Limited |
| Oil Resistance | Tier 1 - Basic |
| Acid Resistance | Tier 3 - Balanced |
| Alkaline Resistance | Tier 2 - Limited |
| Water Resistance | Tier 5 - Excellent |
| Flame Resistance | Tier 1 - Basic |
When to Specify NR
Natural rubber performs best in applications where mechanical demands are high but chemical exposure is limited.
| Use NR when… | Avoid NR when… |
|---|---|
| High tear resistance is critical | Exposed to petroleum oils or fuels |
| Part undergoes repeated dynamic flex | UV, ozone, or outdoor weathering |
| Maximum elasticity and rebound needed | Operating above 80°C continuously |
| Cost-sensitive, non-oil environment | Contact with strong acids or solvents |
| Excellent adhesion to metal inserts required | Food or medical contact required |
Notes: NR’s stress-crystallization behavior gives it a unique advantage in high-deformation applications — the more it stretches, the stronger it becomes in that direction. No synthetic elastomer fully replicates this property.
Custom Parts We Make in NR
Natural rubber’s high elasticity and tear resistance make it well-suited for dynamic and load-bearing components. Common parts we produce include:
→ Vibration isolation mounts — NR’s rebound characteristics dampen broadband frequencies effectively in industrial and automotive assemblies
→ Rubber bumpers and buffers — High energy absorption for impact protection in material handling and machinery
→ Custom grommets — Where flexibility and tear resistance matter more than chemical resistance
→ Anti-vibration pads — Floor and equipment mounting pads for machinery noise reduction
→ Rubber-to-metal bonded parts — NR bonds exceptionally well to steel and aluminum substrates
If your drawing specifies NR or you’re working from functional requirements, contact our engineering team to discuss compound selection and hardness range.
Industries That Use NR
Natural rubber components appear across industries where mechanical performance under dynamic load is the primary design requirement.
Industrial Equipment
Vibration mounts, bumpers, and isolation pads in heavy machinery and conveyor systems where consistent energy absorption matters across shift cycles.
Suspension bushings, engine mounts, and jounce bumpers in applications where NR’s fatigue resistance under repeated compression outperforms synthetic alternatives.
Construction
Bridge bearings, expansion joint pads, and structural isolation components where long-term load-bearing performance is critical.
General Manufacturing
Press pads, tooling components, and custom buffers where abrasion resistance and tear strength are the primary selection criteria.
Compare Materials
Natural rubber is the right choice for many dynamic applications, but if your environment introduces chemical or thermal constraints, consider these alternatives:
If your application involves… | Consider instead |
Oil, fuel, or hydraulic fluid exposure | |
Outdoor UV or ozone weathering | |
Moderate oil + weather resistance | |
Continuous temps above 150°C | |
Extreme chemical resistance | |
High abrasion and mechanical wear | |
Cost-sensitive, general-purpose non-oil use | |
Air/gas impermeability or vibration damping |
Not sure which material fits your application? Send us your requirements and we’ll recommend the right compound.