🧩 EPR – Ethylene Propylene Rubber
(Saturated synthetic elastomeric material obtained by copolymerizing ethylene and propylene. EPR is highly resistant to ozone, UV, and water, with long-term stable elasticity but limited oil resistance. It is a thermoset rubber that cannot be melted or welded.)
🔹 What is EPR
EPR (Ethylene Propylene Rubber) is a saturated copolymer without diene monomers, meaning it has no double bonds in its backbone. This structure makes it incredibly resistant to oxygen and ozone aging. At ReplastMD, we handle it mainly in electrical insulation and cooling system gaskets. Unlike its thermoplastic counterparts, EPR is a thermoset material, which means it hardens permanently during vulcanization and cannot be re-melted.
🔧 Composition & Properties
- Polymer Base: Ethylene + Propylene copolymer.
- Density: 0.86 – 0.90 g/cm³.
- Hardness (Shore A): 40 – 80.
- Operating Range: –50 °C to +120 °C.
- Chemical Resistance: Excellent for water/steam/weak acids.
- Weakness: Highly sensitive to oils, fuels, and hydrocarbon solvents.
🚗 Where EPR is used in the automotive industry
| Component | Example parts | Observations |
| Electrical Insulation | Cables, connectors, tubes | Stable dielectric, does not degrade |
| Sealing Gaskets | Caps, rings, plugs | Resists water, steam, alkaline media |
| Anti-vibration | Bellows, buffers, sleeves | Elastic, but softer than EPDM |
| Static Seals | Extruded profiles | Great outdoor durability |
🔧 Welding Temperature and Methods
| Method | Compatibility | Observations |
| Hot Air | ❌ Cannot be welded | Thermoset – does not flow or reshape |
| Heat Plate (Mirror) | ❌ Impossible | Chars above 150 °C |
| Extrusion | ❌ N/A | Cannot be reshaped after vulcanization |
| Chemical Bonding | ✅ Recommended | Specialized rubber adhesives / primers |
🔩 Compatibility (Bonding)
- ✅ Compatible: EPR, EPDM, NR, SBR.
- ❌ Incompatible: PP, PE, PA, PC, PVC – no adhesion without chemical treatment.
💡 ReplastMD Recommendation: EPR cannot be thermally welded. For repairs, use chemical bonding with elastomeric adhesives or cold vulcanization. For high-precision technical parts, total replacement is recommended.
🧠 How to Identify EPR
- Soft, matte, rubbery texture; no greasy gloss.
- Very elastic but feels softer than standard EPDM.
- ReplastMD practical test: Does not soften under heat. If exposed to flame, it produces heavy black smoke.
- Common markings: >EPR<, >VISTALON<, >NORDEL<.