EPDM for Custom Molded Components — Properties, Applications & Specifications
Table of Contents
Material Properties & Specifications
| Common names / abbreviations | EPDM |
|---|---|
| Polymer structure / monomer system | Ethylene, Propylene, Diene terpolymer |
| Tg (°C) / Brittle Point | -54 °C to -59 °C |
| Density (g/cm³) | 0.86 |
| Hardness range (Shore A/D) | 30 - 90 Shore A |
| Tensile strength (MPa) | 3.4 - 24.1 |
| Elongation at break (%) | 100 - 700 |
| 100% / 300% modulus (MPa) | 0.68 - 20.6 at 100% |
| Rebound / tanδ (temp + freq) | 40 - 75 % Rebound |
| Compression set (%) | 20 - 60 % |
| Continuous service temp (°C) | -40°C to 148°C |
| Environmental & Fluid Resistance | Ozone: Excellent | Oil: 50 to 80% Swell |
| ASTM D2000 Callouts | M4AA 407 A13 B13 C12 F17 |
| Electrical properties | Vol Res: 2x10^16 - 1x10^17 ohm-cm |
| Thermal properties | Thermal Cond: 0.15 W/mK |
| Tear Resistance | Tier 2 - Limited |
| Abrasion Resistance | Tier 4 - Strong |
| Gas Impermeability Resistance | Tier 2 - Limited |
| Oxygen Resistance | Tier 4 - Strong |
| Ozone Resistance | Tier 5 - Excellent |
| Weathering Resistance | Tier 5 - Excellent |
| Oil Resistance | Tier 1 - Basic |
| Acid Resistance | Tier 4 - Strong |
| Alkaline Resistance | Tier 4 - Strong |
| Water Resistance | Tier 5 - Excellent |
| Flame Resistance | Tier 5 - Excellent |
When to Specify EPDM
Review the specific environmental and chemical conditions of your application to determine if EPDM is the correct elastomer choice.
| Use EPDM when… | Avoid EPDM when… |
| The component faces continuous UV radiation and ozone exposure | The system uses petroleum-based oils, lubricants, or fuels |
| The application involves prolonged contact with steam or hot water up to 150°C | The part requires extreme dynamic abrasion resistance |
| The seal will be exposed to polar solvents like ketones or alcohols | |
| The design requires strong dielectric properties for electrical insulation | The component requires FDA compliance without specialized food-grade compounding |
| The assembly must maintain flexibility in cold temperatures down to -40°C | Continuous operating temperatures exceed 150°C |
The most critical factor in specifying EPDM is its resistance to environmental degradation caused by ozone and ultraviolet light. Because the main polymer chain contains only single bonds (saturation), there are no reactive sites for ozone to attack and cleave the polymer backbone. This makes it the primary choice for any component requiring decades of outdoor survivability without surface crazing or mechanical failure.
Custom Parts We Make in EPDM
Fenlora engineers and molds specific components designed to leverage EPDM’s unique environmental and thermal properties.
→ Radiator Coolant O-Rings: EPDM withstands prolonged exposure to ethylene glycol and hot water mixtures without swelling or losing its compression set. This is critical for sealing fluid lines in the automotive engine compartment. Read more about the detailed usage of EPDM in the liquid cooling sector.
→ Outdoor Enclosure Grommets and Wheels: The inherent UV and ozone stability prevents environmental embrittlement over decades of continuous sunlight exposure. Procurement engineers frequently specify this for telecommunications and electrical infrastructure. or you can explore our custom EPDM wheels designed specifically for long-term outdoor mobility.
→ HVAC Vibration Isolators: Low-temperature flexibility down to -40°C ensures the dampening mounts absorb mechanical frequencies without stiffening and transferring vibration in freezing conditions. These are heavily used in commercial rooftop ventilation units.
→ Brake System Diaphragms: EPDM’s compatibility with non-petroleum-based automotive brake fluids prevents chemical swelling and degradation under cyclic pressure environments.
If your drawing specifies EPDM or you’re working from functional requirements, contact our engineering team to discuss compound selection and hardness range.
Industries That Use EPDM
Electrical
Engineers specify EPDM for outdoor enclosure grommets and blind plugs due to its high dielectric strength. It completely resists the UV degradation and ozone cracking that destroys natural rubber, protecting sensitive infrastructure from moisture.
Used heavily for coolant O-rings and fluid line seals, EPDM ensures leak-free performance under extreme thermal cycling. The material prevents compression set failures when exposed to hot water and ethylene glycol mixtures in engine compartments.
HVAC and Industrial Machinery
Vibration isolator mounts and condenser pads rely on this elastomer to dampen continuous mechanical stress. It maintains structural flexibility down to -40°C, ensuring reliable vibration isolation for outdoor ventilation units.
Plumbing and Water Systems
Municipal water systems utilize EPDM for pipe coupling gaskets and valve seals. Its exceptional resistance to chloramine-treated water and steam prevents the elastomer from swelling or breaking down in high-pressure fluid environments.
Compare Materials
If EPDM’s vulnerabilities conflict with your operational environment, evaluate these alternative elastomers.
| If your application involves… | Consider instead |
|---|---|
| Oil, fuel, or hydraulic fluid exposure | Nitrile (NBR) |
| Extreme chemical or solvent resistance | Viton (FKM) |
| Continuous temps above 150°C | Silicone (VMQ) |
| High dynamic flex and tear resistance | Natural Rubber (NR) |
| High abrasion and mechanical wear | Polyurethane (AU/EU) |
| Moderate oil + weather resistance | Neoprene (CR) |
| Air/gas impermeability | Butyl (IIR) |
| Cost-sensitive general-purpose use | SBR |
Not sure which material fits your application? Send us your requirements and we’ll recommend the right compound.